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1
Gao, Zong Jun, Jia Guo Ren, Jia Liang Li, Hong Cao, Qian Qian Wu, Zhao Xiang Zhang und Hai Hui Ma. „The Comprehensive Test for Geothermal Tail-Water Disposal“. Advanced Materials Research 403-408 (November 2011): 4522–27. http://dx.doi.org/10.4028/www.scientific.net/amr.403-408.4522.
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Geothermal reservoirs and groundwater resources in layered porous media in large sedimentary basins have enormous exploitation potential because of their extensive distribution, great quantity, and feasible temperatures and drilling depths. The discharge of geothermal wastewater (i.e. tail-water) on the surface is a serious environmental issue because of its high salinity content, so the Bureau of Geology Exploration and Mineral Resources Exploitation in Shandong Province, China called for the study of the disposal technique of the geothermal tail-water. The disposal test process is as follows: take the waste of geothermal water to make physics-chemistry preparative disposal; filtration with manganese-sand set and/or double-medium equipment; filtration with ion exchange resins; nanofiltration membrane separation; and reverse osmosis separation. After separation, the cheap, clean water can be used as a material for chemical plants. However, in the case of deeply embedded geothermal groundwater resources, connate water(buried water), or bad recharge conditions, must be dried up for a long time exploitation, causing ground depression. Therefore, it is concluded that systems utilizing reinjection, i.e. closed-circuit cycle mode injection, in sandstone reservoirs are ideal for the realization of sustainable exploitation of the geothermal groundwater resources with favorable environmental conditions on the surface.
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Nicassio, Francesco, und Gennaro Scarselli. „Simulation and Test of Discrete Mobile Surfaces for a RC-Aircraft“. Aerospace 6, Nr. 11 (05.11.2019): 122. http://dx.doi.org/10.3390/aerospace6110122.
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Morphing structures suitable for unmanned aerial vehicles (UAVs) have been investigated for several years. This paper presents a novel lightweight, morphing concept based on the exploitation of the “lever effect” of a bistable composite plate that can be integrated in an UAV horizontal tail. Flight dynamics equations are solved in Simulink environment, thus being able to simulate and compare different flight conditions with conventional and bistable command surfaces. Subsequently, bistable plates are built by using composite materials, paying particular attention to dimensions, asymmetric stacking sequence and total thickness needed to achieve bistability. NACA0011 airfoil is chosen for proving this concept. Wind tunnel tests demonstrate that the discrete surface is capable of withstanding the aerodynamic pressure. A remotely piloted vehicle is employed to test the discrete horizontal tail command during the take-off. The results show that, choosing a proper configuration of constraints, stacking sequence and aspect ratio for the bistable laminate, it is possible to tailor the snap-through mechanism. The proposed concept appears lighter and increases aerodynamic efficiency when compared to conventional UAV command surfaces.
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Fratto, Melanie A., und Andrew K. Davis. „Do black-furred animals compensate for high solar absorption with smaller hairs? A test with a polymorphic squirrel species“. Current Zoology 57, Nr. 6 (01.12.2011): 731–36. http://dx.doi.org/10.1093/czoolo/57.6.731.
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Abstract In polymorphic mammalian species that display multiple color forms, those with dark, or melanic pelage would be prone to overheating, especially if they live in warm climates, because their fur absorbs solar energy at a higher rate. However, experimental studies indicate that certain physical properties of fur of dark individuals appear to prevent, or minimize heat stress, although it is not clear what properties do so. Here, we tested the possibility that black-furred individuals simply have shorter or thinner hair fibers, which would create a lighter (in terms of weight) coat or one that allows greater air flow for evaporative cooling. We examined museum specimens of eastern fox squirrels Sciurus niger, a species native to the United States and one that displays brown, grey or all-black pelage color, and used image analysis procedures to quantify hairs from the dorsal surface and tail. From examination of 43 specimens (19 brown, 9 black and 15 grey), and 1,720 hairs, we found no significant difference in hair lengths across color morphs, but significant differences in hair fiber widths. Black squirrels had thinner body hairs than other forms (7% thinner), but thicker tail hairs (9% thicker) than the others. Given that the dorsal surface would be directly exposed to solar radiation, we interpret this to be an adaptation to prevent heat stress during the day. The thicker tail hairs may be an adaptation for nighttime thermoregulation, since squirrels sleep with their tails wrapped around their bodies. These results add to a growing literature body of the functional significance of mammalian pelage.
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Warguła, Łukasz, Bartosz Wieczorek und Mateusz Kukla. „The selection of the tail lift parameters“. AUTOBUSY – Technika, Eksploatacja, Systemy Transportowe 20, Nr. 1-2 (28.02.2019): 364–67. http://dx.doi.org/10.24136/atest.2019.067.
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People moving on wheelchairs overcome the forces of resistance such as: air resistance, resistance of the ascent, inertia force and rolling resistance force. Under certain conditions of use of the wheelchair, the only resistance that must overcome the driving force during the movement is the rolling resistance force. This situation occurs during uniformly rectilinear movement, on a flat level surface at speeds of up to 20 km/h, because at this speed the air resistance is negligible. Rolling resistance is mainly influenced by the mass of the rolling object and the rolling resistance coefficient of the running gear. The value of the rolling resistance coefficient can be influenced, among others, by the surface, type and level of pressure in the tire, and the measurement method. There are test methods that in the resistance of rolling beyond the resistance resulting from the contact of the tire with the surface take into account the resistance to connection of the wheel with the driven object. One of them is the innovative method of measuring the rolling resistance coefficient of objects equipped only with the running gear according to the patent application P.424484 and the developed device for these tests in accordance with the patent application P.424483. The article presents the results of wheelchair rolling resistance test with a classic drive system and wheel attachment. These results show differences in the aspect of rolling resistance of classic wheelchairs with wheelchairs equipped with innovative propulsion solutions, such as a lever drive system or a hybrid drive. The study was financed from the means of the National Centre for Research and Development under LIDER VII programme, re-search project no. LIDER/7/0025/L-7/15/NCBR/2016.
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Khan, Abid Ali, Muhammad Arif Ashraf, Asim Shehzad, Abroon Jamal Qazi und Imran Hayat. „Computational and experimental studies of horizontal tail flutter suppression“. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, Nr. 1 (14.08.2017): 34–43. http://dx.doi.org/10.1177/0954410017725363.
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Flutter is an extremely violent instability that may result in catastrophic failure. Thus, flutter clearance test is one of the critical phases in qualification of an aircraft’s airworthiness. During design and development process of an aircraft, flutter problems were experienced on an aerodynamic surface (horizontal tail). In order to tackle the observed problem, a number of approaches to optimize the design for flutter speed were computationally and experimentally studied and evaluated. This paper presents and discusses the outcomes of these studies. A hybrid approach based on evaluations and design change constraints has been proposed to suppress the flutter of the horizontal tail.
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Gao, Zhenxing, Debao Wang und Zhiwei Xiang. „A Method for Estimating Aircraft Vertical Acceleration and Eddy Dissipation Rate in Turbulent Flight“. Applied Sciences 10, Nr. 19 (28.09.2020): 6798. http://dx.doi.org/10.3390/app10196798.
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Atmospheric turbulence is a typical risk that threatens the flight safety of civil aviation aircraft. A method of estimating aircraft’s vertical acceleration in turbulence is proposed. Based on the combination of wing and horizontal tail, the continuous change of aerodynamic force in turbulent flight is obtained by unsteady vortex ring method. Vortex rings are assigned on the mean camber surface to further improve the computing accuracy. The incremental aerodynamic derivatives of lift and pitching moment are developed, which can describe the turbulence effects on aircraft. Furthermore, a new acceleration-based eddy dissipation rate (EDR) algorithm was developed to estimate the turbulence severity. Compared with wind tunnel test data, the aerodynamic performance of the lifting surface was computed accurately. A further test on wing–tail combination showed that the computed pitching moment change due to control-surface deflections approaches the aircraft-modeling data. The continuous change of vertical acceleration at any longitudinal locations of aircraft is obtained in turbulent flight. Compared with traditional transfer function-based EDR algorithms, the proposed algorithm shows higher accuracy and stability. Furthermore, the adverse influence of aircraft maneuvering on EDR estimation is eliminated.
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Kern, Martin, Perry Bartelt, Betty Sovilla und Othmar Buser. „Measured shear rates in large dry and wet snow avalanches“. Journal of Glaciology 55, Nr. 190 (2009): 327–38. http://dx.doi.org/10.3189/002214309788608714.
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AbstractWe present estimates of internal shear rates of real-scale avalanches that are based on velocity measurements. Optical velocity sensors installed on the instrument pylon at the Swiss Vallée de la Sionne test site are used to measure flow velocities at different flow heights of three large dry and wet snow avalanches. Possible sources of error in the correlation analysis of the time-lagged reflectivity signals measured by optical sensors are identified for real-size avalanches. These include spurious velocities due to noise and elongated peaks. An appropriate choice of the correlation length is essential for obtaining good velocity estimates. Placing restrictions on the maximum possible accelerations in the flow improves the analysis of the measured data. Coherent signals are found only in the dense flowing cores. We observe the evolution of shear rates at different depths between the front and tail of the flowing avalanche. At the front, large shear rates are found throughout the depth; at the tail, plug flows overriding highly sheared layers near the bottom of the flow are observed. The measured velocities change strongly with height above the ground and fluctuations around the measured mean velocity can be identified. We find that the dense flows are laminar, undergoing a transition from supercritical to subcritical flow behaviour from the head to the tail. Furthermore, we provide real-scale experimental evidence that the mean shear rate and the magnitude of velocity fluctuations increase with the mean discharge.
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Li, Gang, Kai Pang, Lan Chi, Chang Xiang Liu, Li Jiang und Li Qun Mo. „Experimental Study on Performance of Phase Change Thermal Storage Kang“. Applied Mechanics and Materials 525 (Februar 2014): 451–56. http://dx.doi.org/10.4028/www.scientific.net/amm.525.451.
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In this paper, the author build a new type of Kang with paraffin as its heating surface. Paraffin is a kind of phase change material ,which can stroage and release heat at a relatively constant temperature. It can make full use of the heat of the smoke in the Kang and extend the Kang heating period. We do comparison test of the the traditional Kang room and the phase change Kang room and related temperature was recorded. The tested result shows that the average temperature of the head, medium and tail of traditional Kang varies greatly,the maximum difference of the temperature is over 20°C. While the average temperatures of the head, middle and tail of the phase change thermal storage Kang are 32.59°C, 28.38°C and 26.12°C, Kang surface temperature distribution is more uniform, which improves the comfort of Kang surface. The indoor temperature with phase change thermal storage Kang shows an upward trend after the fuels burnt out until the wee hours. And the average indoor temperature is 1 °C higher than the comparision room. The phase change thermal storage Kang greatly improves the thermal comfort of its heating surface and indoor temperature.
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Tang, Yong, Liang Liang, You Xia Pang, Zong Ming Zhu und Yan Xu. „Research of Erosion, Cavitation and Their Interactive Wears of Fluid Machinery Three-Phase Flow“. Applied Mechanics and Materials 212-213 (Oktober 2012): 1261–66. http://dx.doi.org/10.4028/www.scientific.net/amm.212-213.1261.
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There are erosion and cavitation in the wear of flow passage components of fluid machinery at the same time. With simulating the working conditions of hydraulic turbine, this paper studies the flow field (pressure field and fluid concentration distribution) of vapor-liquid-solid three-phase on the surface of test rotary table when there are erosion, cavitation and interactive wear on the test rotary table under different environmental pressure with computational fluid dynamics i.e. CFD method, and erosion and cavitation interactive wear test is made on the rotary wear test-bed. The results show that during interaction, the pressure on test piece surface is higher than that in erosion and cavitation, and both high pressure area and bubble area appear near the cavitation hole which is shown as fish-tail shape; with the environmental pressure increased and the interaction, the pressures on test piece surface and bubble are increased, and wear is thereupon increased; Under the interaction, the numerically computational area with many bubbles and big pressure gradient is basically the same as test piece wearing area, so the numerical computational results are consistent with the test results well.
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Xiao, Kanyan, Jennifer Garner, Kathleen M. Buckley, Peter A. Vincent, Christine M. Chiasson, Elisabetta Dejana, Victor Faundez und Andrew P. Kowalczyk. „p120-Catenin Regulates Clathrin-dependent Endocytosis of VE-Cadherin“. Molecular Biology of the Cell 16, Nr. 11 (November 2005): 5141–51. http://dx.doi.org/10.1091/mbc.e05-05-0440.
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VE-cadherin is an adhesion molecule critical to vascular barrier function and angiogenesis. VE-cadherin expression levels are regulated by p120 catenin, which prevents lysosomal degradation of cadherins by unknown mechanisms. To test whether the VE-cadherin cytoplasmic domain mediates endocytosis, and to elucidate the nature of the endocytic machinery involved, the VE-cadherin tail was fused to the interleukin (IL)-2 receptor (IL-2R) extracellular domain. Internalization assays demonstrated that the VE-cadherin tail dramatically increased endocytosis of the IL-2R in a clathrin-dependent manner. Interestingly, p120 inhibited VE-cadherin endocytosis via a mechanism that required direct interactions between p120 and the VE-cadherin cytoplasmic tail. However, p120 did not inhibit transferrin internalization, demonstrating that p120 selectively regulates cadherin internalization rather than globally inhibiting clathrin-dependent endocytosis. Finally, cell surface labeling experiments in cells expressing green fluorescent protein-tagged p120 indicated that the VE-cadherin–p120 complex dissociates upon internalization. These results support a model in which the VE-cadherin tail mediates interactions with clathrin-dependent endocytic machinery, and this endocytic processing is inhibited by p120 binding to the cadherin tail. These findings suggest a novel mechanism by which a cytoplasmic binding partner for a transmembrane receptor can serve as a selective plasma membrane retention signal, thereby modulating the availability of the protein for endo-lysosomal processing.
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Jønholt, Lisa, Cathrine Juel Bundgaard, Martin Carlsen und Dorte Bratbo Sørensen. „A Case Study on the Behavioural Effect of Positive Reinforcement Training in a Novel Task Participation Test in Göttingen Mini Pigs“. Animals 11, Nr. 6 (29.05.2021): 1610. http://dx.doi.org/10.3390/ani11061610.
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In laboratory animal research, many procedures will be stressful for the animals, as they are forced to participate. Training animals to cooperate using clicker training (CT) or luring (LU) may reduce stress levels, and thereby increase animal welfare. In zoo animals, aquarium animals, and pets, CT is used to train animals to cooperate during medical procedures, whereas in experimental research, LU seem to be the preferred training method. This descriptive case study aims to present the behaviour of CT and LU pigs in a potentially fear-evoking behavioural test—the novel task participation test—in which the pigs walked a short runway on a novel walking surface. All eight pigs voluntarily participated, and only one LU pig showed body stretching combined with lack of tail wagging indicating reduced welfare. All CT pigs and one LU pig displayed tail wagging during the test, indicating a positive mental state. Hence, training pigs to cooperate during experimental procedures resulted in a smooth completion of the task with no signs of fear or anxiety in seven out of eight animals. We suggest that training laboratory pigs prior to experimental procedures or tests should be done to ensure low stress levels.
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Troncoso, Renata J., Daniel E. Herzberg, Constanza S. Meneses, Heine Y. Müller, Marianne P. Werner und Hedie Bustamante. „Mechanical/thermal sensitivity and superficial temperature in the stump of long-term tail-docked dairy cows“. PeerJ 6 (18.07.2018): e5213. http://dx.doi.org/10.7717/peerj.5213.
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BackgroundTail docking of dairy cows is a painful procedure that affects animal welfare level. The aims of this study were first to evaluate the response to mechanical and thermal stimulation, and second to determine the superficial temperature of the stump of tail-docked dairy cows.MethodsOne hundred and sixty-four dairy cows were enrolled. From these, 133 cows were assigned to the tail-docked (TD) group and 31 cows were selected as control animals. The following sensory assessments to evaluate pain in tail-docked cows were performed. Sensitivity of the tail region in both groups of animals was evaluated using a portable algometer. Cold and heat sensitivity assessment was performed using a frozen pack (0 °C) and warm water (45 °C), respectively. Pinprick sensitivity was evaluated using a Wartenberg neurological pinwheel. Superficial temperature was evaluated using a thermographic camera. All sensory assessments and superficial temperature were evaluated in the ventral surface of the tail stump (TD) and tail (C).ResultsPressure pain threshold was lower in TD cows (5.97 ± 0.19 kg) compared to control cows (11.75 ± 0.43 kg). Heat and cold sensitivity was higher in the TD cows compared to control cows with 29% and 23% of TD cows responding positively, respectively. Similarly, after pinprick sensitivity test was performed, 93% of TD cows elicited a positive response to stimulation. Tail-docked cows had lower superficial temperature (26.4 ± 0.27 °C) compared to control cows (29.9 ± 0.62 °C).DiscussionPressure pain threshold values in both groups of animals were higher than those previously reported for TD pigs, sows and cows. In contrast, pinprick stimulation evaluates the presence of punctate mechanical hyperalgesia/allodynia, usually related to traumatic nerve injury, and this association may reveal that it is possible that these animals developed a disorder associated to the development of a tail stump neuroma and concurrent neuropathic pain, previously reported in TD lambs, pigs and dogs. Thermal sensitivity showed that TD cows responded positively to heat and cold stimulation. These findings suggest that long-term TD cows could be suffering hyperalgesia/allodynia, which may be indicative of chronic pain. Lower superficial temperature in the stump may be associated to sympathetic fiber sprouting in the distal stump, which can lead to vasoconstriction and lower surface temperatures. Further studies are needed in order to confirm neuroma development and adrenergic sprouting.
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DAHLVIK, PETER, GUILLERMO BLUVOL, KARL-HEINZ KAGERER, MANFRED ARNOLD und DAN VARNEY. „Influence of topcoat pigment particle size distribution on tail-edge pick resistance in sheet-fed offset printing“. June 2012 11, Nr. 6 (01.07.2012): 51–58. http://dx.doi.org/10.32964/tj11.6.51.
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This paper describes ground calcium carbonate pigment particle size distribution and its influence on the tail-edge picking of pilot-coated paper as determined in full-scale sheet-fed offset printing. A tailor-made method was developed using a modified printing plate and high-tack inks to assess surface strength in terms of edge picking. In addition to the type, fineness, and particle size distribution of the ground calcium carbonate pigment, we also evaluated the solids content of the coating color, binder level, clay usage, and calendering. The printing test method provided differentiation relative to the investigated parameters, and it was possible to correlate these results with laboratory test data on ink-coating interaction and mercury intrusion porosimetry. Maximizing the solids content of the formulation to some extent compensated for the loss of pick resistance that followed binder reduction. Other laboratory tests showed poor correlation with the observed degree of edge picking.
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Ramsey, P. M., und T. F. Page. „Interaction between High Speed Nylon Fiber and Unlubricated Ceramic Textile Guides“. Textile Research Journal 62, Nr. 12 (Dezember 1992): 715–28. http://dx.doi.org/10.1177/004051759206201204.
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The friction and wear behavior of alumina and titania textile guides in contact with high speed, dry nylon filaments has been studied using a novel, on-line, friction measuring device. The titania guides were worn very quickly to produce smooth grooves, which resulted in a large increase in fiber-guide friction. The alumina guides showed no appreciable wear during the short 1 hour tests, but a large amount of polymer deposit was produced. The morphology of the deposit was determined by the alumina guide topography. The smoother guides were smeared with polymer over the contact region. This adhesive wear process again resulted in a smoothing of the guide surface and a large rise in friction. By contrast, the rougher guides produced small particles of polymer debris by an abrasive wear process. These particles collected in a “tail region” beyond the fiber exit point. Because this did not affect the guide surface in the contact region, friction remained fairly constant during the test, but at the expense of some damage to the surfaces of the filaments. From a friction viewpoint, and if the filament damage is acceptable, this is the preferred guide surface for such an application.
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Liu, Xintao, Yifang Ban und Songnian Li. „An Across-Country Comparison of the Hierarchical Spatial Structures of Cities“. GEOMATICA 68, Nr. 3 (September 2014): 207–17. http://dx.doi.org/10.5623/cig2014-305.
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This paper investigates the hierarchical structures of 29 selected European countries from the perspective of blocks and natural cities and makes an across-country comparison among the countries. Blocks are minimum cycles consisting of road segments in the road network of a whole country; natural cities are defined as the aggregations of small blocks. We test the size distributions of blocks and natural cities at the country level and find that both exhibit heavy-tailed distributions. The power law distribution of city sizes indicates the presence of the scaling property. Therefore, the cities in a country can be repeatedly grouped into a similar two-tier structure of head and tail via the head/tail division rule. The ascending tiers represent the small, medium, large and mega cities. Accordingly, a simple model is developed to evaluate and cross compare the degree of similarity and stability of the scaling properties and hierarchical structures of cities. Moreover, cities and blocks are the functional units of a country, and the correlation coefficient values between city sizes/number of blocks and economic factors (i.e., gross domestic product and population) are up to 0.87. We further conjecture that the compared results of hierarchies can serve as an indicator to assess a country's economic system.
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Edelstein, Jerry, und Stuart Bowyer. „EUV Observations of Pulsars“. International Astronomical Union Colloquium 160 (1996): 291–95. http://dx.doi.org/10.1017/s0252921100041749.
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AbstractThree pulsars have been detected with the Lexan (100 Å )filter of the EUVE Deep Survey telescope: the middle-aged isolated pulsars, PSR B0656+14 and Geminga, plus the aged millisecond pulsar PSR J0437–4715. The EUV detections have been used both alone and in combination with observations in other bandpasses to limit the physical state of the objects and to test theories regarding neutron star cooling and re-heating mechanisms. For Geminga, the EUVE data suggests the presence of an optical cyclotron spectral feature superimposed on the Rayleigh-Jeans continuum tail from a hot pulsar surface. We summarize EUV pulsar observations and results.
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Mahdi Sajedi, Sayyed, Parviz Ghadimi, Mohammad Sheikholeslami und Mohammad A. Ghassemi. „Experimental and numerical analyses of wedge effects on the rooster tail and porpoising phenomenon of a high-speed planing craft in calm water“. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, Nr. 13 (06.03.2019): 4637–52. http://dx.doi.org/10.1177/0954406219833722.
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This paper presents experimental and numerical investigation of stability and rooster tail of a mono-hull high-speed planing craft with a constant deadrise angle. Initially, a one-fifth scale model was tested in a towing tank, which showed porpoising phenomenon at 8 m/s (equal to the speed of sailing). Subsequently, two wedges of 5 and 10 mm heights, based on the boundary layer calculations, were mounted on the aft section of the planing hull. These wedges were shown to increase the lift at the aft section. These experiments were carried out at different speeds up to 10 m/s in calm water. The experimental results indicated that the installed wedges reduced the trim, drag, and the elapsed time for reaching the hump peak, and also eliminated the porpoising condition. All these test cases were also numerically simulated using Star CCM+ software. The free surface was modeled using the volume of fluid scheme in three-dimensional space. The examined planing craft had two degrees of freedom, and overset mesh technique was used for space discretization. The obtained numerical results were compared with experimental data and good agreement was displayed in the presented comparisons. Ultimately, the effect of the wedge on the rooster tail behind the planing craft was studied. The results of this investigation showed that by decreasing the trim at a constant speed, the height of the generated wake profile (rooster tail) behind the craft decreases, albeit its length increases.
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McLennan, Hanna J., Stefan Lüpold, Pete Smissen, Kevin C. Rowe und William G. Breed. „Greater sperm complexity in the Australasian old endemic rodents (Tribe: Hydromyini) is associated with increased levels of inter-male sperm competition“. Reproduction, Fertility and Development 29, Nr. 5 (2017): 921. http://dx.doi.org/10.1071/rd15425.
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Spermatozoa exhibit considerable interspecies morphological variation across mammals, especially among murid rodents. In Australasia, most murids in the tribe Hydromyini have a spermatozoon with a highly complex head exhibiting an apical hook, characteristic of most murids, and two projections that extend from its upper concave surface, the ventral processes. In the present study we performed a phylogenetically controlled comparison of sperm morphology across 45 species of hydromyine rodents to test the hypothesis that the length and angle of both the apical hook and ventral processes, as well as the length of the sperm tail, increase with relative testes mass as a proxy for differences in levels of inter-male sperm competition. Although both sperm head protrusions exhibited considerable variation in their length and angle across species, only the angles increased significantly in relation to relative testes mass. Further, the length of the sperm flagellum was positively associated with relative testes mass. These results suggest that, in hydromyine rodents, the angle of the apical hook and ventral processes of the sperm head, as well as the sperm tail length, are likely to be sexually selected traits. The possible functional significance of these findings is briefly discussed.
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Pasieka, Tracy Jo, Lucie Maresova, Kimiyasu Shiraki und Charles Grose. „Regulation of Varicella-Zoster Virus-Induced Cell-to-Cell Fusion by the Endocytosis-Competent Glycoproteins gH and gE“. Journal of Virology 78, Nr. 6 (15.03.2004): 2884–96. http://dx.doi.org/10.1128/jvi.78.6.2884-2896.2004.
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ABSTRACT The gH glycoprotein of varicella-zoster virus (VZV) is a major fusogen. The realigned short cytoplasmic tail of gH (18 amino acids) harbors a functional endocytosis motif (YNKI) that mediates internalization in both VZV-infected and transfected cells (T. J. Pasieka, L. Maresova, and C. Grose, J. Virol. 77: 4194-4202, 2003). During subsequent confocal microscopy studies of endocytosis-deficient gH mutants, we observed that cells transfected with the gH tail mutants exhibited marked fusion. Therefore, we postulated that VZV gH endocytosis served to regulate cell-to-cell fusion. Subsequent analyses of gH+gL transfection fusion assays by the Kolmogorov-Smirnov statistical test demonstrated that expression of the endocytosis-deficient gH mutants resulted in a statistically significant enhancement of cell-to-cell fusion (P < 0.0001) compared to wild-type gH. On the other hand, coexpression of VZV gE, another endocytosis-competent VZV glycoprotein, was able to temper the fusogenicity of the gH endocytosis mutants by facilitating internalization of the mutant gH protein from the cell surface. When the latter results were similarly analyzed, there was no longer any enhanced fusion by the endocytosis-deficient gH mutant protein. In summary, these studies support a role for gH endocytosis in regulating the cell surface expression of gH and thereby regulating gH-mediated fusion. The data also confirm and extend prior observations of a gE-gH interaction during viral glycoprotein trafficking in a VZV transfection system.
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Paschmann, G., S. Haaland, B. U. Ö. Sonnerup, H. Hasegawa, E. Georgescu, B. Klecker, T. D. Phan, H. Rème und A. Vaivads. „Characteristics of the near-tail dawn magnetopause and boundary layer“. Annales Geophysicae 23, Nr. 4 (03.06.2005): 1481–97. http://dx.doi.org/10.5194/angeo-23-1481-2005.
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Abstract. The paper discusses properties of the near-tail dawnside and boundary layer, as obtained from Cluster plasma and magnetic field measurements during a single skimming orbit on 4 and 5 July 2001 that included 24 well-defined crossings by all four spacecraft. As a result of variations of the interplanetary magnetic field, the magnetic shear across the local varied between ~0° and ~180°. Using an improved method, which takes into account acceleration and thickness variation, we have determined the orientation, speed, thickness and current for the 96 individual crossings. The orientations show clear evidence of surface waves. Magnetopause thicknesses range from ~100 to ~2500km, with an average of 753km. The speeds range from less than 10up to more than 300, with an average of 48. Both results are consistent with earlier ISEE and AMPTE results obtained for the dayside magnetopause. Importantly, scaling the thicknesses to the ion gyro radius or the ion inertial length did not reduce the large dynamic range. There is also no significant dependence of thickness on magnetic shear. Current densities range from ~0.01 up to ~0.3uA, with an average value of 0.05 . By including some extra crossings that did not involve all four spacecraft, we were able to apply the Walén test to a total of 60 by Cluster 1 and 3, and have classified 19 cases as rotational discontinuities (RDs), of which 12 and 7 were sunward and tailward of an X-line, respectively. Of these 60 crossings, 26 show no trace of a boundary layer. The only with substantial boundary layers are into the plasma mantle. Of the 26 without a boundary layer, 8 were identified as RDs. Since reconnection produces wedge-shaped boundary layers emanating from the X-line, RDs without may be considered close to the X-line, in which case the observed magnetic shear and Alfvén Mach number should be representative of the conditions at the X-line itself. It is therefore important that four of the eight cases had shear angles ≤100, i.e. the reconnecting fields were far from being anti-parallel, and that all eight cases had Alfvén Mach numbers MA>1 in the adjoining magnetosheath. Another important conclusion can be drawn from the without a that were tangential discontinuities (TDs). To observe TDs with no at such large distances from the subsolar point appears to rule out diffusion over large portions of the as an effective means for plasma transport across the magnetopause.
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Muangphra, Ptumporn, und Ravi Gooneratne. „Comparative Genotoxicity of Cadmium and Lead in Earthworm Coelomocytes“. Applied and Environmental Soil Science 2011 (2011): 1–7. http://dx.doi.org/10.1155/2011/218929.
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To determine genotoxicity to coelomocytes,Pheretima peguanaearthworms were exposed in filter paper studies to cadmium (Cd) and lead (Pb) for 48 h, at concentrations less than the LC10—Cd: 0.09, 0.19, 0.38, 0.75, and 1.50 μg cm−2; Pb: 1.65, 3.29, 6.58, 13.16, and 26.32 μg cm−2. For Cd at 0.75 μg cm−2, in the micronucleus test (detects chromosomal aberrations), significant increases () in micronuclei and binucleate cells were observed, and in the comet assay (detects DNA single-strand breaks), tail DNA% was significantly increased. Lead was less toxic with minimal effects on DNA, but the binucleates were significantly increased by Pb at 3.29 μg cm−2. This study shows that Cd is more acutely toxic and sublethally genotoxic than Pb toP. peguana. Cadmium caused chromosomal aberrations and DNA single-strand breaks at 45% of the LC10concentration. Lead, in contrast, did not induce DNA damage but caused cytokinesis defects.
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Bell, Michael M., Wen-Chau Lee, Cory A. Wolff und Huaqing Cai. „A Solo-Based Automated Quality Control Algorithm for Airborne Tail Doppler Radar Data“. Journal of Applied Meteorology and Climatology 52, Nr. 11 (November 2013): 2509–28. http://dx.doi.org/10.1175/jamc-d-12-0283.1.
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AbstractAn automated quality control preprocessing algorithm for removing nonweather radar echoes in airborne Doppler radar data has been developed. This algorithm can significantly reduce the time and experience level required for interactive radar data editing prior to dual-Doppler wind synthesis or data assimilation. The algorithm uses the editing functions in the Solo software package developed by the National Center for Atmospheric Research to remove noise, Earth-surface, sidelobe, second-trip, and other artifacts. The characteristics of these nonweather radar returns, the algorithm to identify and remove them, and the impacts of applying different threshold levels on wind retrievals are presented. Verification was performed by comparison with published Electra Doppler Radar (ELDORA) datasets that were interactively edited by different experienced radar meteorologists. Four cases consisting primarily of convective echoes from the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX), Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX), Hurricane Rainband and Intensity Change Experiment (RAINEX), and The Observing System Research and Predictability Experiment (THORPEX) Pacific Asian Regional Campaign (T-PARC)/Tropical Cyclone Structure-2008 (TCS08) field experiments were used to test the algorithm using three threshold levels for data removal. The algorithm removes 80%, 90%, or 95% of the nonweather returns and retains 95%, 90%, or 85% of the weather returns on average at the low-, medium-, and high-threshold levels. Increasing the threshold level removes more nonweather echoes at the expense of also removing more weather echoes. The low threshold is recommended when weather retention is the highest priority, and the high threshold is recommended when nonweather removal is the highest priority. The medium threshold is a good compromise between these two priorities and is recommended for general use. Dual-Doppler wind retrievals using the automatically edited data compare well to retrievals from interactively edited data.
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Huang, Zhengfei, Zhifeng Wang, Chuanhua Li, Kaifeng Yin, Dan Hao und Jing Lan. „Application of Plasma-Sprayed Zirconia Coating in Dental Implants: Study in Implants“. Journal of Oral Implantology 44, Nr. 2 (01.04.2018): 102–9. http://dx.doi.org/10.1563/aaid-joi-d-17-00020.
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The aim was to investigate the osseointegration of a novel coating—plasma-sprayed nanostructured zirconia (NSZ)—for dental implants. Nanostructured zirconia coating on non-thread titanium implant was prepared by plasma spraying, and the implant surface morphology, surface roughness, and wettability were measured. In vivo, nanostructured zirconia-coated implants were inserted in rabbit tibia, and the animals were sacrificed at 2, 4, 8, and 12 weeks after implantation. The bond strength between implant and bone was measured with the removal torque (RTQ) test. Osseointegration was observed by scanning electron microscopy (SEM), microcomputerized tomography (micro CT), and histological analyses. Quantified parameters were calculated, including removal torque, bone volume to tissue volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation/spacing (Tb.Sp), and bone-implant contact (BIC) percentage. The statistical differences were detected with a two-tail Mann-Whitney U test (SPSS 20.0). The surface roughness (1.58 μm) and wettability (54.61°) of a nanostructured zirconia-coated implant was more suitable than the titanium implant (0.598 μm, 74.38°) for osseointegration and hierarchical surface morphology seen on the zirconia coating. The histological analyses showed that a zirconia-coated implant induced earlier and had more condensed bone formation than did the titanium implant at 2 and 4 weeks. Quantified parameters showed the significant differences between these 2 groups at an early healing period, but the differences between the 2 groups decreased with an increased healing period. All these results demonstrated that plasma-sprayed zirconia coated implants induced better bone formation than did titanium implants at an early stage.
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Chajec, Wojciech. „Comparison of flutter calculation methods based on ground vibration test result“. Aircraft Engineering and Aerospace Technology 91, Nr. 3 (04.03.2019): 466–76. http://dx.doi.org/10.1108/aeat-03-2018-0102.
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PurposeA low-cost but credible method of low-subsonic flutter analysis based on ground vibration test (GVT) results is presented. The purpose of this paper is a comparison of two methods of immediate flutter problem solution: JG2 – low cost software based on the strip theory in aerodynamics (STA) and V-g method of the flutter problem solution and ZAERO I commercial software with doublet lattice method (DLM) aerodynamic model and G method of the flutter problem solution. In both cases, the same sets of measured normal modes are used. Design/methodology/approachBefore flutter computation, resonant modes are supplied by some non-measurable but existing modes and processed using the author’s own procedure. For flutter computation, the modes are normalized using the aircraft mass model. The measured mode orthogonalization is possible. The flutter calculation made by means of both methods are performed for the MP-02 Czajka UL aircraft and the Virus SW 121 aircraft of LSA category. FindingsIn most cases, both compared flutter computation results are similar, especially in the case of high aspect wing flutter. The Czajka T-tail flutter analysis using JG2 software is more conservative than the one made by ZAERO, especially in the case of rudder flutter. The differences can be reduced if the proposed rudder effectiveness coefficients are introduced. Practical implicationsThe low-cost methods are attractive for flutter analysis of UL and light aircraft. The paper presents the scope of the low-cost JG2 method and its limitations. Originality/valueIn comparison with other works, the measured generalized masses are not used. Additionally, the rudder effectiveness reduction was implemented into the STA. However, Niedbal (1997) introduced corrections of control surface hinge moments, but the present work contains results in comparison with the outcome obtained by means of the more credible software.
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Bartelt, Perry, und Othmar Buser. „Frictional relaxation in avalanches“. Annals of Glaciology 51, Nr. 54 (2010): 98–104. http://dx.doi.org/10.3189/172756410791386607.
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AbstractWe use velocity profile measurements captured at the Vallée de la Sionne test site, Switzerland, to find experimental evidence for the value of extreme, Voellmy-type runout parameters for snow avalanche flow. We apply a constitutive relation that adjusts the internal shear stress as a function of the kinetic energy associated with random motion of the snow granules, R. We then show how the Voellmy dry-Coulomb and velocity-squared friction parameters change (relax) as a function of an increase in R. Since the avalanche head is characterized by high random energy levels, friction decreases significantly, leading to rapidly moving and far-reaching avalanches. The relaxed friction parameters are near to values recommended by the Swiss avalanche dynamics guidelines. As the random kinetic energy decreases towards the tail, friction increases, causing avalanches to deposit mass and stop even on steep slopes. Our results suggest that the Voellmy friction model can be effectively applied to predict maximum avalanche velocities and maximum runout distances. However, it cannot be applied to model the full range of avalanche behaviour, especially to find the distribution of mass in the runout zone. We answer a series of questions concerning the role of R in avalanche dynamics.
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Rezvani, A., M. Mayer, I. Qin, J. Brunner und Bob Chylak. „Stitch Bond Process of Pd-Coated Cu Wire: Experimental and Numerical Studies of Process Parameters and Materials“. International Symposium on Microelectronics 2013, Nr. 1 (01.01.2013): 000312–17. http://dx.doi.org/10.4071/isom-2013-tp42.
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Cost reduction is the main driver in the recent transition to Cu wire bonding from predominate Au wire bonding. Other cost reduction in packaging comes from new developments in substrates and lead frames, for example, Pre-Plated Frames (PPF) and uPPF for QFP and QFN reduce the plating and material cost. However, 2nd bonds (stitch bonds) can be more challenging on some of the new leadframe types due to the rough surface finish and thin plating thickness. Pd-coated Cu (PCC) wire has been recently introduced to improve the wire bonding process with bare Cu wire, mainly to improve reliability and enhance the stitch bond process. More fundamental studies are required to understand the influences of bonding parameters and bonding tools to improve stitch bondability. The stitch bond process of 0.7 mil diameter PCC wire on Au/Ni/Pd-plated quad flat-no lead (QFN) PPF substrate is investigated in this study. Two capillaries with the same geometry but different surface finishes are used to investigate the effect of capillary surface finish on the stitch bond process. The two capillary types are a polished finish type which is commonly used for Au wire bonding, and a granular finish capillary that has a much rougher surface finish. Process window between no stick on lead (NSOL) and short tail is compared. The effect of process parameters including bond force and table scrub amplitude is studied. The process window test results revealed that the granular capillary has larger process window and a lower chance of short tail occurrence. It has been shown that a higher scrub amplitude increases the chance of successful stitch bond formation. To further compare the capillary surface finishes, 3 sets of parameter settings with different bond force and scrub amplitude are tested. For all three parameter sets tested, the granular capillary showed better quality in bond strength. The granular capillary resulted in higher stitch pull strength compared to the polished type. A finite element model (FEM) of the process was developed to better understand the experimental observations. The amount of surface expansion (plastic deformation) of the wire at the wire and substrate interface was extracted from the model and attributed to the degree of adhesion (bonding). The model was used to confirm the experimental observation of adhesion (bonding) with different surface finish.
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Wu, Zeng, Xiao Jun Ning und Ping Rui Zhao. „Analysis of Fretting Wear of Type II Fastener Elastic Bar“. Applied Mechanics and Materials 178-181 (Mai 2012): 1469–73. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.1469.
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The main function of fastener was achieved by elastic bar. The traditional method for the study of fatigue stress, strain analysis, which was not reflected the true situation, because the elastic bar in the work with other members of the contact surface between the mutual movement of tiny was created, i.e. fretting. The shear stress（ ）, relative displacement（ ） and two of the product（ ） of elastic bar was calculated out by applying Coulomb friction model of nonlinear contact theory of simulation of elastic bar and the surrounding contact element. Theoretical analysis was shown that, if the fretting wear in fatigue fracture was played a major role, it should be located in a section of the and of the value of the biggest point of attachment. Fastener fatigue tests was shown that, a fracture was found at the tail of elastic bar and baffle contact, which was between the value and value of the maximum point and closer to the value for maximum point. Crack was created because of fretting wear of tail of elastic bar and baffle, then the pollution source was formatted, and crack was propagated under the repeated effect, and the fracture of elastic bar was created eventually. The theoretical analysis of elastic bar of fretting wear was shown correctly by the fatigue test, and the improved design of elastic bar for a improving fatigue life was provided scientifly.
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Wang, Tong, Nathalie Courtois-Coutry, Gerhard Giebisch und Michael J. Caplan. „A tyrosine-based signal regulates H-K-ATPase-mediated potassium reabsorption in the kidney“. American Journal of Physiology-Renal Physiology 275, Nr. 5 (01.11.1998): F818—F826. http://dx.doi.org/10.1152/ajprenal.1998.275.5.f818.
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Isoforms of the H-K-ATPase participate in active K resorption in the renal collecting tubule. The cytoplasmic tail of the β-subunit of the gastric H-K-ATPase includes a 4 amino acid motif which is highly homologous to tyrosine-based endocytosis signals. We have generated transgenic mice expressing an H-K-ATPase β-subunit in which the tyrosine residue in this sequence has been mutated to alanine. Mice expressing the mutated protein manifest constitutive hypersecretion of gastric acid, demonstrating that the β-subunit tyrosine-based motif is required for the regulated endocytosis of the H-K pump and hence the cessation of gastric acid output. To test the possibility that the tyrosine-based sequence in the tail of the H-K-ATPase β-subunit plays a role in regulating the function of renal H-K-ATPases, we examined renal K clearance in normal and in transgenic mice. Blood pressure, urine volume, glomerular filtration rate (GFR), plasma Na, and Na excretion are similar in control and transgenic mice. However, plasma K concentrations are significantly higher in transgenic mice (4.76 ± 0.13 meq/l in transgenic and 4.12 ± 0.04 meq/l in control; n = 9, P < 0.05) and K excretion is lower in the transgenic animals (fractional excretion of K was 26.2 ± 3.62% in transgenic and 50.1 ± 4.78% in control; n = 9, P < 0.01). These data suggest that the tyrosine-based signal in the cytoplasmic tail of the H-K-ATPase β-subunit functions in the kidney as it does in the stomach to internalize H-K pump and thus inactivate pump function. Its elimination may result in the constitutive presence of the pump at the cell surface and lead to excessive urinary K reabsorption.
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Geng, Huimin, Jae-Woong Lee, Zhengshan Chen, Behzad Kharabi Masouleh, Christian Hurtz, Eugene Park, Gang Xiao et al. „IL2RA (CD25) Recruits Inhibitory Phosphatases to the Cell Membrane and Mediates Negative Feedback Control of STAT5 Signaling in Acute Lymphoblastic Leukemia“. Blood 124, Nr. 21 (06.12.2014): 788. http://dx.doi.org/10.1182/blood.v124.21.788.788.
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Abstract Background and hypothesis: CD25 (IL2RA, interleukin 2 receptor α chain) is a transmembrane protein with a 13aa cytoplasmic tail. CD25 cooperates with β- and γ-chains in binding IL-2, but does not contribute to cytokine signaling. During normal B cell development, CD25 is specifically upregulated on the surface of IL7-dependent pre-B cells and is also expressed on the surface of a subset of human pre-B ALL cases. CD25-expressing ALL is typically associated with poor clinical outcome. For these reasons, we studied the functional significance of CD25 expression on human pre-B ALL cells. Results: Flow cytometry and immunohistochemistry staining on a large panel of patient samples (n=416; MDACC, ECOG) revealed specific cell surface expression of CD25 in Ph+ ALL and Ph-like ALL, which are both high-risk subtypes of ALL. In agreement with selective expression on high-risk subsets, high expression levels of CD25 at the time of diagnosis were predictive of poor overall clinical outcome in these studies (P=0.005). BCR-ABL1 in Ph+ ALL and related tyrosine kinases in Ph-like ALL strongly activate STAT5, which then induces transcriptional activation of the IL2RA locus. Since Stat5 is also active during normal pre-B cell differentiation, we first analyzed B cell development in Il2ra-/- mouse bone marrow. Il2ra-/- B cell development was blocked at the pre-B cell stage, consistent with specific upregulation of CD25 on pre-B cells. In human Ph+ ALL cells, we found IL2RB and IL2RG were not co-expressed with CD25, suggesting a function of CD25 in Ph+ALL that is distinct from IL2 signaling. To test the biological significance of tyrosine kinase/STAT5-induced activation of CD25, we developed an Il2ra-/- mouse model for BCR-ABL1 pre-B ALL. Interestingly, the cytoplasmic tail of CD25 includes phosphorylation sites (S268 and T271) that are known substrates for serine/threonine phosphorylation by PKCα, which was reported to regulate protein phosphatase 2A (PP2A). To investigate interacting proteins with the cytoplasmic tail of CD25, we performed immune precipitation (IP) against the flag-tagged CD25-tail in primary Ph+ ALL cells which were transduced with either a CD25-tail-flag or an EV-flag vector. 2D mass spectrometry and Western blot on the IP products confirmed strong interactions with PKCα and PP2A. Weestern blot analysis confirmed additional interactions with inhibitory phosphatases including PTEN, PTPN6 (SHP1) and Inpp5d (SHIP1) in human Ph+ALL cells. In addition, both 2D MS and Westernblot showed recruitment of the Stat5-feedback inhibitors CISH, SOCS2 and SOCS3 at the CD25 cytoplasmic tail. Studying functional parameters of Il2ra-/-BCR-ABL1 ALL cells, we found impaired proliferation and colony formation capacity and drastically increased increased phosphorylation levels of pABLY412, pSTAT5Y694, pERKT202/Y204, pAKTS473, pP38T180/Y182 and p53. Reconstitution of CD25 expression restored normal phosphorylation levels of these molecules, as well as proliferation and colony formation.In a serial transplant setting, we observed that leukemia initiation in transplant recipients from Il2ra-/- BCR-ABL1 ALL cells required 10- to 100-times higher cell numbers, suggesting that CD25 contributes to leukemia initiation. In addition, CD25 expression is associated with a higher level of drug-resistance: In patient-derived pre-B ALL cells with mixed CD25Low and CD25High populations, the standard chemotherapy agent vincristine selectively induced apoptosis of in CD25Low but not CD25High ALL cells. An anti-CD25 immunotoxin drugs efficiently eradiated CD25High leukemia cells and thereby overcame drug-resistance against vincristine. Conclusions: Our studies identified CD25 as a surface receptor that mediates membrane recruitment of PP2A and CISH, SOCS2, negative feedback regulators of STAT5. CD25 is transcriptionally activated by STAT5 and therefore specifically expressed on high-risk ALL subtypes with oncogenic activation of the Stat5 pathway (Ph+ ALL and Ph-like ALL). We propose that CD25-mediated negative feedback control stabilizes oncogenic tyrosine kinase signaling and mediates drug-resistance in Ph+ ALL and Ph-like ALL cells. Targeted inhibition using CD25-directed immunotoxins may be useful in new approaches to overcome drug-resistance in Ph+ ALL and Ph-like ALL. Disclosures No relevant conflicts of interest to declare.
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Krzysiak, Andrzej. „Wind Tunnel Tests of the Tu-154M Aircraft Aerodynamic Characteristics“. Journal of KONES 26, Nr. 3 (01.09.2019): 113–20. http://dx.doi.org/10.2478/kones-2019-0064.
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Abstract Determination of possible manoeuvres to be performed by the aircraft requires knowledge of its aerodynamic characteristics including, in particular, characteristics of the aircraft at configuration with deflected control surfaces. In this article, the wind tunnel tests results of the model of passenger Tu-154M aircraft manufactured at the scale 1:40 are presented. The model was designed and manufactured by the Military University of Technology based on the Tu-154M aircraft geometry obtained by full-scale object scanning. The model mapped all aircraft control surfaces, along with the gaps between these surfaces and the main wing part. During the tests all the model’s control surface like, flaps, ailerons, spoilers, slots, rudder, elevator and tail plane were deflected at the same deflection angles range as they are used in the full scale aircraft. The aerodynamic characteristics of the tested Tu-154M aircraft model were measured by the 6-component internal balance. Based on the obtained measurements the aircraft model aerodynamic coefficients were calculated. In the article the basic aerodynamic characteristics of the tested Tu-154M aircraft model i.e. lift, drag coefficients as well as pitching, yawing and rolling moment coefficients versus model angles of attack and sideslip angles were presented. The tests were performed in the Institute of Aviation low speed wind tunnels T-1 of the 1.5 m diameter test section at the undisturbed velocity, V∞ = 40 m/s.
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Homan, S. M., A. M. Mercurio und S. E. LaFlamme. „Endothelial cells assemble two distinct alpha6beta4-containing vimentin-associated structures: roles for ligand binding and the beta4 cytoplasmic tail“. Journal of Cell Science 111, Nr. 18 (15.09.1998): 2717–28. http://dx.doi.org/10.1242/jcs.111.18.2717.
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The alpha6beta4 laminin binding integrin functions in the assembly of type I hemidesmosomes, which are specialized cell-matrix adhesion sites found in stratified epithelial cells. Although endothelial cells do not express all the components of type I hemidesmosomes, endothelial cells can express the alpha6beta4 integrin. Because endothelial cells lose expression of alpha6beta4 in culture, we expressed recombinant alpha6beta4 in the dermal microvascular endothelial cell line, HMEC-1, to test whether endothelial cells can assemble adhesion structures containing alpha6beta4. Using immunofluorescence microscopy, we found that recombinant alpha6beta4 concentrates specifically in a novel fibrillar structure on the basal surface of endothelial cells in the absence of an exogenous laminin substrate. This localization is regulated by an intracellular mechanism, because the beta4 cytoplasmic domain is sufficient to direct a reporter domain (IL-2R) to the fibrillar structures independently of recombinant alpha6beta4. In addition, this IL-2R-beta4 chimera is sufficient to recruit the intermediate filament-associated protein HD1/plectin to these fibrillar structures and this also occurs in the absence of recombinant alpha6beta4. The fibrillar localization pattern, as well as the recruitment of HD1/plectin, requires the first and second fibronectin type III repeats and the connecting segment of the beta4 tail. In addition, when endothelial cells are provided a laminin 5-rich matrix, recombinant alpha6beta4 redistributes from the fibrillar structure to type I hemidesmosome-like structures. The beta4 cytoplasmic domain can also direct a reporter domain to these type I hemidesmosome-like structures; however, this process is dependent upon the expression of recombinant alpha6beta4 Biochemical analysis indicates that both the fibrillar and the type I hemidesmosome-like structures are associated with the vimentin intermediate filament cytoskeleton. Thus, the results illustrate that endothelial cells have the essential components necessary to assemble at least two distinct alpha6beta4-containing and vimentin-associated structures on their basal surface and that the alpha6beta4 cytoplasmic tail and the availability of specific alph6beta4 ligands regulate receptor localization to these structures.
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Seng, Lee Yeh, und Berna Hascakir. „Role of Intermolecular Forces on Surfactant-Steam Performance into Heavy Oil Reservoirs“. SPE Journal 26, Nr. 04 (19.05.2021): 2318–23. http://dx.doi.org/10.2118/201513-pa.
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Summary This study investigates the role of polar fractions of heavy oil in the surfactant-steamflooding process. Performance analyses of this process were done by examination of the dipole-dipole and ion-ion interactions between the polar head group of surfactants and the charged polar fraction of crude oil, namely, asphaltenes. Surfactants are designed to reduce the interfacial tension (IFT) between two immiscible fluids (such as oil and water) and effectively used for oil recovery. They reduce the IFT by aligning themselves at the interface of these two immiscible fluids; this way, their polar head group can stay in water and nonpolar tail can stay in the oil phase. However, in heavy oil, the crude oil itself has a high number of polar components (mainly asphaltenes). Moreover, the polar head group in surfactants is charged, and the asphaltene fraction of crude oils carries reservoir rock components with charges. The impact of these intermolecular forces on the surfactant-steam process performance was investigated with 10 coreflood experiments on an extraheavy crude oil. Nine surfactants (three anionic, three cationic, and three nonionic surfactants) were tested. Results of each coreflood test were analyzed through cumulative oil recovery and residual oil content. The performance differences were evaluated by polarity determination through dielectric constant measurements and by ionic charges through zeta potential measurements on asphaltene fractions of produced oil and residual oil samples. The differences in each group of surfactants tested in this study are the tail length. Results indicate that a longer hydrocarbon tail yielded higher cumulative oil recovery. Based on the charge groups present in the polar head of anionic surfactants resulted in higher oil recovery. Further examinations on asphaltenes from produced and residual oils show that the dielectric constants of asphaltenes originated from the produced oil, giving higher polarity for surfactant-steam experiments conducted with longer tail length, which provide information on the polarity of asphaltenes. The ion-ion interaction between produced oil asphaltenes and surfactant head groups were determined through zeta potential measurements. For the most successful surfactant-steam processes, these results showed that the changes on asphaltene surface charges were becoming lower with the increase in oil recovery, which indicates that once asphaltenes are interacting more with the polar head of surfactants, then the recovery rate increases. Our study shows that the surfactant-steamflooding performance in heavy oil reservoirs is controlled by the interaction between asphaltenes and the polar head group of surfactants. Accordingly, the main mechanism that controls the effectiveness of the process is the ion-ion interaction between the charges in asphaltene surfaces and the polar head group of crude oils. Because crude oils carry mostly negatively charged reservoir rock particles, our study suggests the use of anionic surfactants for the extraction of heavy oils.
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Selokar, N. L., P. Sharma, D. Kumar, R. K. Sharma und P. S. Yadav. „24 EFFECT OF DONOR CELL TYPE ON IN VITRO AND IN VIVO DEVELOPMENTAL COMPETENCE OF CLONED BUFFALO (BUBALUS BUBALIS) EMBRYOS“. Reproduction, Fertility and Development 28, Nr. 2 (2016): 142. http://dx.doi.org/10.1071/rdv28n2ab24.
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Selection of the donor cell type for somatic cell NT is very important based on its capability to be reprogrammed by the oocyte cytoplasm. A very wide variety of donor cells of different origin have been used for somatic cell NT, having differences in the overall efficiency. The aim of this study was to compare the cloning efficiency of donor cells derived from the ventral side of origin of tail skin and seminal plasma of a buffalo bull (age: 3 years old). Somatic cells from skin and seminal plasma were isolated and cultured as described by Selokar et al. (2014 PLOS ONE 9(3), e90755). Cultured seminal plasma cells had classic epithelial morphology, grew in clusters, were hexagonal in outline shape, and were positive for immunocytochemical detection of keratin marker, indicating that they were of epithelial origin, whereas tail-derived cells were spindle in shape and found positive for vimentin expression, indicating the fibroblast origin. To determine their reprogramming potential, these cells between passages 5 to 8 were used for the production of buffalo cloned embryos by handmade cloning as per the method described by Selokar et al. (2012 Theriogenology 78, 930–936). In brief, oocytes were isolated from slaughter-house ovaries and matured in vitro. After 21 h of maturation, cumulus cell mass and zona pellucida were removed by enzymatic treatment, hyaluronidase and pronase, respectively. Zona-free buffalo oocytes were enucleated on the basis of protrusion cone. A single somatic cell was attached to an enucleated oocyte with addition of phytohemagglutinin, followed by sandwich type of electrofusion between the somatic cell-bearing oocyte and enucleated oocyte using BTX electrofusion machine. Fused oocytes were activated by 4 μM calcium ionophore for 5 min and incubated in 2 mM 6-DMAP for 4 h and were cultured in K-RVCL-50® medium for 7 days on a flat surface in a 4-well dish in an incubator (5% CO2 and 38.5°C temperature). The total numbers of embryos reconstructed from tail-derived cells and semen-derived cells were 132 and 158, respectively. Cleavage and blastocyst rate were calculated from total embryos cultured, and data were analysed by Student’s t-test. We found no significant effect on both cleavage (89.30 ± 2.1 v. 94.1 ± 0.6) and blastocyst rate (40.7 ± 4.0 v. 43.1 ± 9.6) for the embryos produced from cells derived from tail and seminal plasma. To study the in vivo developmental competence of embryos derived from the 2 donor cell types, one embryo of each cell type was transferred into 6 recipient animals. Pregnancies were confirmed by ultrasonography at 30 to 35 days after transfer and monitored regularly at 15-day intervals up to 90 days. Three pregnancies were found for tail-derived cells, whereas no pregnancy was obtained for semen-derived cells. Out of 3 pregnancies obtained, 1 embryonic death was observed before 45 days, and 2 are continuing at advance stage. In conclusion, tail-derived cells are the better donor cell choice for buffalo somatic cell NT research. Currently, our focus is on epigenetic reprogramming behaviour of these 2 different cell types to elucidate the possible reprogramming mechanism.
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Boonen, Marielle, Roberta Rezende de Castro, Gaëlle Cuvelier, Isabelle Hamer und Michel Jadot. „A dileucine signal situated in the C-terminal tail of the lysosomal membrane protein p40 is responsible for its targeting to lysosomes“. Biochemical Journal 414, Nr. 3 (27.08.2008): 431–40. http://dx.doi.org/10.1042/bj20071626.
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Transport of newly synthesized lysosomal membrane proteins from the TGN (trans-Golgi network) to the lysosomes is due to the presence of specific signals in their cytoplasmic domains that are recognized by cytosolic adaptors. p40, a hypothetical transporter of 372 amino acids localized in the lysosomal membrane, contains four putative lysosomal sorting motifs in its sequence: three of the YXXϕ-type (Y6QLF, Y106VAL, Y333NGL) and one of the [D/E]XXXL[L/I]-type (EQERL360L361). To test the role of these motifs in the biosynthetic transport of p40, we replaced the most critical residues of these consensus sequences, the tyrosine residue or the leucine–leucine pair, by alanine or alanine–valine respectively. We analysed the subcellular localization of the mutated p40 proteins in transfected HeLa cells by confocal microscopy and by biochemical approaches (subcellular fractionation on self-forming Percoll density gradients and cell surface biotinylation). The results of the present study show that p40 is mistargeted to the plasma membrane when its dileucine motif is disrupted. No role of the tyrosine motifs could be put forward. Taken together, our results provide evidence that the sorting of p40 from the TGN to the lysosomes is directed by the dileucine EQERL360L361 motif situated in its C-terminal tail.
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Miller, P., J. Agrell, J. Olsson und K. Sjörs. „Axisymmetric afterbody experiments for CFD validation“. Aeronautical Journal 98, Nr. 974 (April 1994): 137–46. http://dx.doi.org/10.1017/s0001924000049988.
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Summary An experiment is described which was undertaken specifically to provide CFD validation data for the case of transonic flow over nozzle afterbodies. The tests were undertaken with the AGARD standard 10° and 15° axisymmetric boat-tail geometries. Onset Mach numbers in the range 0·80-0·99 and subsonic and under-expanded jet plumes were employed in the tests. Test conditions were selected which provided a range of afterbody flow features from largely attached to shock-induced separated flows. A uniquely detailed set of surface pressure and flowfield data are presented. The flow data were acquired with a two-component laser Doppler anemometer (LDA) and define the mean and fluctuating flow components at about 500 spatial locations for each of these complex transonic flowfields. Additional information was recorded which fully defines the required computational boundary conditions. Also presented is a detailed study of the necessary attributes of windtunnel CFD validation data. It is demonstrated that relatively high blockage experiments using cost-effective windtunnels can be used to generate CFD validation data if proper account is taken of the model/tunnel interference.
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Adjamskiy, Sergey, Rostislav Podolskyi und Ganna Kononenko. „Investigation of plastic properties of AISI 316l steel by method of registration of macrolocalization fields“. System technologies 4, Nr. 135 (05.04.2021): 3–11. http://dx.doi.org/10.34185/1562-9945-4-135-2021-01.
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Selective laser melting is one of the modern methods of manufacturing parts in the production of machine-building equipment, a special place is occupied by complex technological processes used in the manufacture of high-load units of pneumatic-hydraulic system from heat-resistant alloys. The research was carried out on samples made of powder material - stainless steel AISI 316L martensite class. Metallographic studies showed that the density of the sample is 99.83%, the structure of the samples is a martensitic structure of equilibrium constructed tracks. Tests to determine the mechanical properties were performed in accordance with ISO 6892 on an INSTRON test machine. From the tensile diagram it was found that the yield strength was 376.56 MPa, the maximum point of temporary resistance of the sample - 615, 40 MPa 319 seconds after the start of the test. The control of the surface roughness was performed using a BioBase device. The working area of the tensile sample consisted of two areas: a roughness area of 5 μm, which accounted for 80% of the working part of the sample (zones A and Б) and 20% of the working part of the sample (zone Б), the roughness was 17 μm. According to the results of microstructure studies and studies by the method of registration of macrolocalization fields of the working zone of the samples, it was found that the destruction began from the surface of the samples from microconcentrators due to different roughness. It is established that the surface and subsurface layer with increased roughness in comparison with the main body has a smaller elongation by 10.84%. From microstructural studies of the working zone in the area of the gap, it was found that the destruction began from the surface of the samples between zones A and Б. During the research in zone A and Б, one of the concentrators of the gap was detected. As a result of the study, it was found that the destruction began with the surface of the samples and the place of change of its roughness. The mechanism of deformation of the sample from AISI 316L steel is shown, the scheme of extraction of tail sections of tracks and crack propagation in the conditions of tensile testing of the sample is constructed.
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Ijaware, V. A. „Comparative Analysis of Ellipsoidal Height and Shuttle Radar Topographic Mission Elevation“. Journal of Applied Sciences and Environmental Management 24, Nr. 8 (09.09.2020): 1397–402. http://dx.doi.org/10.4314/jasem.v24i8.14.
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Ellipsoidal elevation represents a precise geospatial data type within the analysis and modelling of various hydrological and ecological phenomenon required in preserving the human environment. Likewise, Shuttle Radar Topographic Mission (SRTM) has created an unparalleled data set of global elevations that are freely available for modelling ubiquitous environmental applications. This research aims to carry out a comparative analysis of ellipsoidal heights and SRTM heights with the following objectives: downloading DEM’s (SRTM) data covering the study area, determining the spot heights within the boundary in conventional method, extract DEM’S heights within the boundary of the study area, and compared the heights in the conventional method with DEM’S heights. South GPS and Leica Total Station were used to acquire data for control extension and spot heightening respectively while the elevation of SRTM data was obtained by transforming the X and Y data from GPS observationto Longitude and Latitude before using ArcGIS 10.6 to extract the elevation of the boundary pillar and all the spot heights which were relatively compared in terms of its products- heights, contour, 3-D wireframe, 3-D surface model, and overlaid of contour on shaded relief. The results of the study showed that vertical difference using conventional method and SRTM dataset ranges between -2.345m to 11.026m. Also, the hypothesis tested using a two-tail student t-test and F-test revealed that one mean is not significantly different from the other at 95% confidence level. The research recommends that the products obtained for the two systems can be used interchangeably.
Keywords: Shuttle radar topographic mission, Ellipsoidal elevation, contour, 3D wireframe, 3D surface model
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Wang, Haofeng, Zhenxing Gao, Hongbin Gu und Kai Qi. „Estimation of Aircraft-Dependent Bumpiness Severity in Turbulent Flight“. Applied Sciences 11, Nr. 4 (18.02.2021): 1796. http://dx.doi.org/10.3390/app11041796.
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Atmospheric turbulence threatens flight safety of civil aviation aircraft by inducing aircraft bumpiness. A severity estimation method of aircraft bumpiness in turbulent flight is explored according to in-situ Eddy Dissipation Rate (EDR) indicator. With the turbulence intensity derived from EDR value, a time series of longitudinal and vertical turbulence was generated according to von Karman turbulence model. In order to obtain the vertical acceleration response of aircraft, the continuous change of aerodynamic force on the assembly of wing and horizontal tail was computed by Unsteady Vortex Lattice Method (UVLM). The computing accuracy was improved by using semi-circle division and assigning the vortex rings on the mean camber surface. Furthermore, the adverse effects of control surface deflections on bumpiness severity estimation can be effectively removed by separating turbulence-induced and aircraft maneuvers-induced aerodynamic force change. After that, the variance of vertical acceleration, as the severity indicator of aircraft bumpiness, was obtained by Welch spectrum estimation. With the refined grid level, the pitching moment change due to control surface deflections can be solved accurately by UVLM. The instantaneous acceleration change obtained by UVLM approximates recorded acceleration data with better accuracy than linear transfer function model. A further test with a set of flight data on the same airway shows that compared with in-situ EDR indicator, the proposed method gives an aircraft-dependent estimation of bumpiness severity, which can not only be used to estimate in-situ bumpiness but also be applied to forecast the bumpiness severity of other different aircrafts.
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Atcha, Fawzia A., Adeela Syed, Beibei Wu, Nate P. Hoverter, Noriko N. Yokoyama, Ju-Hui T. Ting, Jesus E. Munguia, Harry J. Mangalam, J. Lawrence Marsh und Marian L. Waterman. „A Unique DNA Binding Domain Converts T-Cell Factors into Strong Wnt Effectors“. Molecular and Cellular Biology 27, Nr. 23 (24.09.2007): 8352–63. http://dx.doi.org/10.1128/mcb.02132-06.
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ABSTRACT Wnt regulation of gene expression requires binding of LEF/T-cell factor (LEF/TCF) transcription factors to Wnt response elements (WREs) and recruitment of the activator β-catenin. There are significant differences in the abilities of LEF/TCF family members to regulate Wnt target genes. For example, alternatively spliced isoforms of TCF-1 and TCF-4 with a C-terminal “E” tail are uniquely potent in their activation of LEF1 and CDX1. Here we report that the mechanism responsible for this unique activity is an auxiliary 30-amino-acid DNA interaction motif referred to here as the “cysteine clamp” (or C-clamp). The C-clamp contains invariant cysteine, aromatic, and basic residues, and surface plasmon resonance (SPR) studies with recombinant C-clamp protein showed that it binds double-stranded DNA but not single-stranded DNA or RNA (equilibrium dissociation constant = 16 nM). CASTing (Cyclic Amplification and Selection of Targets) experiments were used to test whether this motif influences WRE recognition. Full-length LEF-1, TCF-1E, and TCF-1E with a mutated C-clamp all bind nearly identical WREs (TYYCTTTGATSTT), showing that the C-clamp does not alter WRE specificity. However, a GC element downstream of the WRE (RCCG) is enriched in wild-type TCF-1E binding sites but not in mutant TCF-1E binding sites. We conclude that the C-clamp is a sequence-specific DNA binding motif. C-clamp mutations destroy the ability of β-catenin to regulate the LEF1 promoter, and they severely impair the ability of TCF-1 to regulate growth in colon cancer cells. Thus, E-tail isoforms of TCFs utilize two DNA binding activities to access a subset of Wnt targets important for cell growth.
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Redivo Júnior, Nildo, Camila Dutra de Souza, Ellyn Amanda Fonseca Martins, Tatiana Issa Uherara, Milton Mendes Cattini, Daniel Oliveira Creste, Felipe Rydygier de Ruediger und Marcelo George Mungai Chacur. „Scrotal thermography to assess the seminal quality in Nelore and Girolando bulls“. Semina: Ciências Agrárias 41, Nr. 1 (10.01.2020): 131. http://dx.doi.org/10.5433/1679-0359.2020v41n1p131.
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Bull selection by andrological examination aims to estimate the reproductive capacity of the male. Bulls of zebu origin adapt better to high temperatures than bulls of taurine origin, which may influence scrotum temperature and seminal quality due to the imbalance of testicular thermoregulation. The objective of this study was to investigate the relationship between bioclimatic variables, the temperature of body and scrotal areas, assessed with infrared thermography, and the quality of fresh and post-thawed semen in zebu Nelore bulls (Bos taurus indicus) and Girolando bulls (Bos taurus taurus x Bos taurus indicus). Bulls were kept in pickets with access to water, mineral mix and a diet supplemented with concentrate. Infrared thermographs of the scrotum, orbital globe and muzzle were performed twice a week with a Flir E40 thermal imager. For scrotal thermograms, we analyzed the temperatures of the spermatic cord, proximal and distal portion of the testes and tail of the epididymis using the Flir Tools software. Samples were collected using an artificial vagina and the ejaculates were processed and frozen in liquid nitrogen until further analyses. Data were analyzed with the Tukey test or the Kruskall-Wallis test, depending on their normal distribution. Our results showed differences (p < 0.05) between the two breeds regarding the temperature in the ocular globe, spermatic cord and proximal portion of the scrotum. Nelore bulls presented lower temperature in the body and in certain regions of the scrotum compared to Girolando bulls. Seminal characteristics varied between breeds, with the Nelore breed presenting better semen. Positive correlations were observed between minor sperm defects and ventral regions of the testes and tails of the epididymis in Girolando bulls. Nelore bulls were less influenced by climatic variables and presented lower temperature in skin surface areas in the infrared thermography examination compared to Girolando bulls. Nelore bulls presented superior semen quality in both fresh and thawed samples than Girolando bulls.
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Chen, Juan, Jocelyn Schroeder, Xiaofeng Luo, Robert R. Montgomery und Qizhen Shi. „The Impact of GPIba on the Efficacy of Platelet-Targeted FVIII Gene Therapy in Hemophilia a with Pre-Existing Anti-FVIII Immunity“. Blood 126, Nr. 23 (03.12.2015): 1067. http://dx.doi.org/10.1182/blood.v126.23.1067.1067.
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Abstract Platelets play fundamental roles in hemostasis through surface proteins, e.g. GPIb, and storage proteins, such as von Willebrand factor (VWF). Our previous studies have demonstrated that FVIII ectopically targeted to platelets under control of the platelet-specific aIIb promoter (2bF8) is therapeutic in hemophilia A mice even in the presence of anti-FVIII inhibitory antibodies (inhibitors). Our recent studies have shown that VWF is essential in platelet-targeted FVIII gene therapy of hemophilia A with inhibitors. Without VWF, the clinical efficacy of platelet-FVIII was aborted. In primary hemostasis, platelets adhere to the vessel wall through the binding of GPIb to VWF. Thus, we wanted to explore whether GPIb is critical for maintaining the clinical efficacy of platelet-FVIII gene therapy of hemophilia A in the presence of inhibitors. To address this question, recipient FVIIInull (F8null) mice were immunized with recombinant FVIII (rhF8) to induce anti-FVIII inhibitory antibody development (the inhibitor model). Hematopoietic stem cells (HSCs) from GPIba knockout (Ibnull) mice were transduced with 2bF8 lentivirus and transplanted into rhF8-primed F8null mice under 1100 cGy total body irradiation (2bF8-Ibnull/F8null). As an inhibitor model control (2bF8-F8null/F8null), HSCs from F8null mice were transduced with 2bF8 and transplanted into rhF8-primed recipients under the same preconditioning. After bone marrow transplantation and reconstitution, animals were assessed for transgene expression and phenotypic correction. PCR analysis showed that the 2bF8 transgene was detected in all of the transduced recipients, demonstrating the viability of 2bF8-transduced engraftment. The level of functional platelet-FVIII expression as determined by a Chromogenic assay was 6.37 ± 5.62 mU/108 platelets (n = 6), which appeared to be higher than the level obtained in the inhibitor control group (1.97 ± 0.96 mU/108 platelets, n = 5), but there was no significant difference between these two groups. Since the size of Ibnull platelets is larger and the platelet number is lower than those in F8null mice, we converted FVIII levels into mU/ml whole blood and the level was 10.36 ± 5.33 mU/ml in 2bF8-Ibnull/F8null mice, which is not significantly different from the 2bF8-F8null/F8null mice (9.04 ± 3.38 mU/ml). When the tail bleeding test was used to grade phenotypic correction of the F8null coagulation defect, all transduced recipients in both groups survived beyond a 6-hour tail clipping test and the remaining hemoglobin level in the 2bF8-Ibnull/ F8null group was 46.4 ± 8.5%, which is not significantly different from the 2bF8-F8null/F8null group (48.3 ± 9.7%). The remaining hemoglobin levels in both groups were significantly higher than in the untransduced F8null control, in which only 5 of 12 animals survived beyond the 6-hour tail clipping test with a remaining hemoglobin level of 34.8 ± 7%. Thus, our data suggest that a lack of platelet GPIba does not negate the clinical efficacy of platelet FVIII gene therapy in hemophilia A in the presence of inhibitors. Disclosures Montgomery: Baxter: Consultancy; Bayer: Consultancy; CSL: Consultancy; Biogen: Consultancy; Octapharma: Consultancy; Grifols: Consultancy. Shi:BloodCenter of Wisconsin: Patents & Royalties: METHOD OF INDUCING IMMUNE TOLERANCE THROUGH TARGETTED GENE EXPRESSION..
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Markovitz, Rebecca C., John F. Healey, W. Hunter Baldwin, Ernest T. Parker, Shannon L. Meeks und Pete Lollar. „Decreasing the Humoral Response to Factor VIII By Targeted Deletion of Factor VIII - Specific B Cells“. Blood 124, Nr. 21 (06.12.2014): 238. http://dx.doi.org/10.1182/blood.v124.21.238.238.
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Abstract The development of neutralizing anti-factor VIII (fVIII) antibodies (inhibitors) remains the most significant complication in the treatment of hemophilia A patients. Treatment of inhibitor patients consists of management of bleeding episodes using bypassing agents or porcine fVIII. Inhibitors can be eradicated by immune tolerance induction (ITI) using thrice-weekly administration of large doses of fVIII. However, ITI fails in approximately 30% of patients. Additionally, the median time to tolerance in successful cases is ~18 months, making ITI expensive and inconvenient. In the current study, we used a murine E16 hemophilia A model to test a novel approach to both prevent and eradicate fVIII inhibitors. We hypothesized that conjugation of fVIII to the toxin saporin, a Type I ribosome-inactivating protein, would target fVIII-specific cell surface immunoglobulin and selectively delete fVIII-specific naïve and memory B cells. Recombinant full-length fVIII was covalently linked to saporin using the heterobifunctional crosslinker N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP). To test for eradication of existing fVIII inhibitors by fVIII-saporin, an adoptive transfer protocol was developed to measure fVIII-specific memory B cells. Hemophilia A donor mice were immunized with 2 μg of full-length fVIII by intravenous injection every other week for 8 weeks, followed by a final dose of 4 μg at ten weeks. Four weeks later, the mice were randomized into three treatment groups to receive equimolar doses of saporin, fVIII, or fVIII-saporin. Seven days after treatment, the mice were sacrificed and 4 x 106 plasma cell CD138+-depleted splenocytes were adoptively transferred as a source of fVIII-specific memory B cells into naïve recipient hemophilia A mice. At 24 hours, recipient mice were given a single injection of 0.5, 1.0 or 2.0 μg of recombinant full-length fVIII by tail vein injection. Anti-fVIII IgG antibodies in recipient mice were measured by ELISA 2 and 5 weeks following the fVIII injection. In the absence of fVIII-specific memory B cells from donor mice, naïve hemophilia A mice did not produce detectable anti-fVIII antibodies. Recipient hemophilia A mice receiving splenocytes from fVIII donor and saporin donor mice displayed a dose-dependent increase in anti-fVIII antibodies. In contrast, the slope of the anti-fVIII titer versus dose of fVIII was significantly decreased in recipient mice receiving splenocytes from fVIII-saporin donor mice. To test for prevention of fVIII inhibitor formation by fVIII-saporin, naïve hemophilia A mice were divided into three treatment groups to receive a single dose of saporin, fVIII, or fVIII-saporin by tail vein injection. Seven days after treatment, the mice were immunized by tail vein injection with 2 μg of full-length fVIII every other week for 10 weeks. Anti-fVIII IgG antibodies were measured 1 week after the fourth and sixth injections of fVIII. Anti-fVIII antibody titers were significantly lower in the fVIII-saporin group compared to the fVIII group (1,900 vs. 21,400 (p=0.027, n=4, Mann-Whitney test, see figure) after the fourth injection. After 6 injections, the average anti-fVIII titer of the fVIII group was 23,000 compared to 4,000 in the fVIII-saporin group (p=0.057, n=4, Mann-Whitney test, see figure). In conclusion, our results suggest that infusion of fVIII-saporin results in the depletion of both fVIII-specific naïve B cells and memory B cells. FVIII-saporin potentially could be used in the treatment of congenital hemophilia A patients with inhibitors and patients with acquired hemophilia A. In addition, fVIII-saporin potentially could be used in previously untreated patients with hemophilia A to prevent inhibitor development. Similar therapeutic strategies could be extended to other antigen-specific immune disorders. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.
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Liu, Hao, Jinjiang Shi, Jiasen Li und Chao Liu. „Investigation on the Influence Caused by Shield Tunneling: WSN Monitoring and Numerical Simulation“. Advances in Civil Engineering 2021 (16.02.2021): 1–11. http://dx.doi.org/10.1155/2021/6620706.
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Traditional monitoring techniques are faced with the problems of low acquisition frequency and easy to be affected by the construction environment during the shield tunneling, which cannot meet the actual needs of timeliness monitoring of surrounding environmental impact on shield tunnel construction. Based on this actual demand, a wireless sensor network (WSN) system was used to monitor the response of shield tunnel segments and surrounding buildings during the shield tunneling in this study. According to the result of the signal transmission test, an optimization scheme of microelectromechanical system (MEMS) sensor layout is designed to improve the monitoring efficiency of the WSN system. Through the comparative analysis of WSN system monitoring data and traditional monitoring data, it is found that, with the increasing distance between the monitoring section and the tunnel face, the convergence value of tunnel lining clearance gradually tends to be stable, and the wireless monitoring results of transverse clearance convergence of the tunnel in this section are consistent with the overall deformation trend of the convergence gauge monitoring results. This study also simulated the shield tunneling adjacent buildings using a nonlinear finite element method. A parameter sensitivity analysis of the support pressure of the excavation face and the grouting pressure at the tail of the shield is carried out. The results show that the surface settlement can be reduced by properly increasing the grouting pressure and the support pressure of the excavation face. Moreover, increasing the support pressure of the excavation face has a better inhibition effect on the settlement of the surface soil than increasing the grouting pressure.
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Kasirer-Friede, Ana, Barry Moran, Jennifer Nagrampa-Orje, Ken Swanson, Zaverio M. Ruggeri, Burkhart Schraven, Benjamin G. Neel, Gary Koretzky und Sanford J. Shattil. „ADAP is required for normal αIIbβ3 activation by VWF/GP Ib-IX-V and other agonists“. Blood 109, Nr. 3 (26.09.2006): 1018–25. http://dx.doi.org/10.1182/blood-2006-05-022301.
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Abstract Interaction between von Willebrand factor (VWF) and platelet GP Ib-IX-V is required for hemostasis, in part because intracellular signals from VWF/GP Ib-IX-V activate the ligand-binding function of integrin αIIbβ3. Because they also induce tyrosine phosphorylation of the ADAP adapter, we investigated ADAP's role in GP Ib-IX-V signal transduction. Fibrinogen or ligand-mimetic POW-2 Fab binding to αIIbβ3 was stimulated by adhesion of ADAP+/+ murine platelets to dimeric VWF A1A2 but was significantly reduced in ADAP−/− platelets (P < .01). αIIbβ3 activation by ADP or a Par4 thrombin receptor agonist was also decreased in ADAP−/− platelets. ADAP stabilized the expression of another adapter, SKAP-HOM, via interaction with the latter's SH3 domain. However, no abnormalities in αIIbβ3 activation were observed in SKAP-HOM−/− platelets, which express normal ADAP levels, further implicating ADAP as a modulator of αIIbβ3 function. Under shear flow conditions over a combined surface of VWF A1A2 and fibronectin to test interactions involving GP Ib-IX-V and αIIbβ3, respectively, ADAP−/− platelets displayed reduced αIIbβ3-dependent stable adhesion. Furthermore, ADAP−/− mice demonstrated increased rebleeding from tail wounds. These studies establish ADAP as a component of inside-out signaling pathways that couple GP Ib-IX-V and other platelet agonist receptors to αIIbβ3 activation.
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Hungerford, J. E., M. T. Compton, M. L. Matter, B. G. Hoffstrom und C. A. Otey. „Inhibition of pp125FAK in cultured fibroblasts results in apoptosis.“ Journal of Cell Biology 135, Nr. 5 (01.12.1996): 1383–90. http://dx.doi.org/10.1083/jcb.135.5.1383.
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The tyrosine kinase called pp125FAK is believed to play an important role in integrin-mediated signal transduction. pp125FAK is associated both functionally and spatially with integrins, which are the cell surface receptors for extracellular matrix components. Although the precise function of pp125FAK is not known, two possibilities have been proposed: pp125FAK may regulate the assembly of focal adhesions in spreading or migrating cells, or pp125FAK may participate in a signal transduction cascade to inform the nucleus that the cell is anchored. To test these models in living cells, a peptide representing the focal adhesion kinase (FAK)-binding site of the beta 1 tail was coupled to carrier protein and injected into cultured cells to competitively inhibit the binding of pp125FAK to endogenous integrin, thus inhibiting activation of pp125FAK on a cell-by-cell basis. In addition, an antibody directed against an epitope adjacent to the focal adhesion targeting sequence on pp125FAK was microinjected, as an alternative means of inhibiting pp125FAK activation. It was observed that when rounded cells were injected with either the integrin peptide or the anti-FAK antibody, the cells rapidly began to apoptose, within 4 h after injection. These results indicate that pp125FAK may play a critical role in suppressing apoptosis in fibroblasts.
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Murányi, Marianna, Resat Cinar, Orsolya Kékesi, Erika Birkás, Gabriella Fábián, Beáta Bozó, András Zentai et al. „Ligand-Specific Regulation of the Endogenous Mu-Opioid Receptor by Chronic Treatment with Mu-Opioid Peptide Agonists“. BioMed Research International 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/501086.
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Since the discovery of the endomorphins (EM), the postulated endogenous peptide agonists of the mu-opioid receptors, several analogues have been synthesized to improve their binding and pharmacological profiles. We have shown previously that a new analogue,cis-1S,2R-aminocyclohexanecarboxylic acid2-endomorphin-2 (ACHC-EM2), had elevated mu-receptor affinity, selectivity, and proteolytic stability over the parent compound. In the present work, we have studied its antinociceptive effects and receptor regulatory processes. ACHC-EM2 displayed a somewhat higher (60%) acute antinociceptive response than the parent peptide, EM2 (45%), which peaked at 10 min afterintracerebroventricular (icv)administration in the rat tail-flick test. Analgesic tolerance developed to the antinociceptive effect of ACHC-EM2 upon its repeatedicvinjection that was complete by a 10-day treatment. This was accompanied by attenuated coupling of mu-sites to G-proteins in subcellular fractions of rat brain. Also, the density of mu-receptors was upregulated by about 40% in the light membrane fraction, with no detectable changes in surface binding. Distinct receptor regulatory processes were noted in subcellular fractions of rat brains made tolerant by the prototypic full mu-agonist peptide, DAMGO, and its chloromethyl ketone derivative, DAMCK. These results are discussed in light of the recently discovered phenomenon, that is, the “so-called biased agonism” or “functional selectivity”.
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Ahn, Hyun Sook, Rudy Fuentes, Vincent Hayes, Douglas B. Cines, Vladimir R. Muzykantov, Sergei V. Zaytsev und Mortimer Poncz. „A Human-Specific, Platelet-Targeted, Thrombin-Activatable Urokinase (PLT/uPA-T) Demonstrates Selective Thromboprophylactic Properties in Two in Vivo Models“. Blood 124, Nr. 21 (06.12.2014): 579. http://dx.doi.org/10.1182/blood.v124.21.579.579.
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Abstract Two major clinical limitations to the use of thrombolytic agents are their short half-life and lack of targeting specificity. We aimed to circumvent these limitations by targeting a platelet-bound, thrombin-activatable, low molecular weight urokinase, termed PLT/uPA-T, to nascent thrombi by a combination of two strategies: (1) Attaching the drug through its N-terminal scFv portion to human αIIb/β3 on the surface of platelets with nM affinity. (2) Protecting the uPA from rapid activation/inactivation in the circulation while simultaneously requiring its activation by thrombin through a two amino acid deletion at the plasmin cleavage site that concurrently creates a thrombin cleavage/activation site. These two properties constrain the activity of PLT/uPA-T on mature clots, which express low levels of thrombin and transiently recruit only a few new platelets to the shell rather than the core of the thrombus. These two properties of PLT/uPA-T also enhance the drug’s lifespan by attaching it to the platelet cell surface and preventing its inactivation before reaching its intended target. PLT/uPA-T binds specifically to human platelets and to hαIIb mouse platelets that transgenically expressed human (h) αIIb on its surface. In hαIIb mice, the half-life of retro-orbitally infused PLT/uPA-T was ~2 hours, ~100-fold longer than similarly infused uPA-T and did not cause any spontaneous bleeding or lower platelet counts 4 to 24 hours later. We now report two in vivo models to test the efficacy of the PLT/uPA-T as a thromboprophylactic agent versus uPA-T, taking into account the much shorter circulating half-life of the latter. In the hαIIb mice model, a tail-vein clipping model was done to represent the “mature clot” as follows: following clipping, blood was collected into 37°C water for 10 minutes. The tail was then removed from the water and a bolus of PLT/uPA-T (0.5 µg/g mouse) injected retro-orbitally followed by a continuous infusion of the same dose over the next 30 minutes. uPA-T was similarly infused but both bolus and infusion were given at 10-fold higher doses. A no-drug treatment control was also included. After the drug infusion was started, the tail was placed into fresh 37°C water and bleeding was documented from these “mature clots” over the ensuing 30 minutes. To study “nascent thrombi”, mice were bolused/infused with same drug regimens, and a FeCl3 carotid artery injury study was performed contemporaneously. PLT/uPA-T was as effective at 1/10th the dose as uPA-T at preventing these “nascent thrombi” (FeCl3 injuries), but did not cause bleeding from “mature clots” (tail clippings) relative to the no-treatment control, while the uPA-T treatment lead to ~5-fold greater rebleeding compared to the no-treatment control (p<0.001) with N > 10 animals per arm. The second in vivo model targeted human platelets infused into immunocompromized NOD-SCID γ-interferon-deficient (NSG) male mice to generate a calculated 10% of all the circulating platelets being human at the initiation of the studies. The pre-drug “mature clots” and the post-drug “nascent thrombi” were both arteriolar laser cremaster injuries. We enumerated mouse platelets incorporated into these thrombi over time. There was an ~50% decrease in the size of laser-induced post-drug “nascent thrombi” after PLT/uPA-T or a 10-fold higher dose of uPA-T relative to no drug treatment. However, PLT/uPA-T did not affect the size of the laser-induced pre-drug “mature clots” relative to no drug-treatment, while there was a decrease in size of the mature clots after treatment with uPA-T. These studies describe two preclinical models of comparative thromboprophylactic efficacy and safety that are independent of drug half-life. Our studies demonstrate that a combination of platelet-targeting and need for thrombin-activation makes PLT/uPA-T a very potent and targeted thrombolytic agent to prevent new thrombus formation, while leaving older, hemostatic clots intact. Disclosures No relevant conflicts of interest to declare.
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Walters, Robert W., Wouter van't Hof, Su Min P. Yi, Mary K. Schroth, Joseph Zabner, Ronald G. Crystal und Michael J. Welsh. „Apical Localization of the Coxsackie-Adenovirus Receptor by Glycosyl-Phosphatidylinositol Modification Is Sufficient for Adenovirus-Mediated Gene Transfer through the Apical Surface of Human Airway Epithelia“. Journal of Virology 75, Nr. 16 (15.08.2001): 7703–11. http://dx.doi.org/10.1128/jvi.75.16.7703-7711.2001.
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ABSTRACT In well-differentiated human airway epithelia, the coxsackie B and adenovirus type 2 and 5 receptor (CAR) resides primarily on the basolateral membrane. This location may explain the observation that gene transfer is inefficient when adenovirus vectors are applied to the apical surface. To further test this hypothesis and to investigate requirements and barriers to apical gene transfer to differentiated human airway epithelia, we expressed CAR in which the transmembrane and cytoplasmic tail were replaced by a glycosyl-phosphatidylinositol (GPI) anchor (GPI-CAR). As controls, we expressed wild-type CAR and CAR lacking the cytoplasmic domain (Tailless-CAR). All three constructs enhanced gene transfer with similar efficiencies in fibroblasts. In airway epithelia, GPI-CAR localized specifically to the apical membrane, where it bound adenovirus and enhanced gene transfer to levels obtained when vector was applied to the basolateral membrane. Moreover, GPI-CAR facilitated gene transfer of the cystic fibrosis transmembrane conductance regulator to cystic fibrosis airway epithelia, correcting the Cl− transport defect. In contrast, when we expressed wild-type CAR it localized to the basolateral membrane and failed to increase apical gene transfer. Only a small amount of Tailless-CAR resided in the apical membrane, and the effects on apical virus binding and gene transfer were minimal. These data indicate that binding of adenovirus to an apical membrane receptor is sufficient to mediate effective gene transfer to human airway epithelia and that the cytoplasmic domain of CAR is not required for this process. The results suggest that targeting apical receptors in differentiated airway epithelia may be sufficient for gene transfer in the genetic disease cystic fibrosis.
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Armstrong, R. Todd, Anna S. Kushnir und Judith M. White. „The Transmembrane Domain of Influenza Hemagglutinin Exhibits a Stringent Length Requirement to Support the Hemifusion to Fusion Transition“. Journal of Cell Biology 151, Nr. 2 (16.10.2000): 425–38. http://dx.doi.org/10.1083/jcb.151.2.425.
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Glycosylphosphatidylinositol-anchored influenza hemagglutinin (GPI-HA) mediates hemifusion, whereas chimeras with foreign transmembrane (TM) domains mediate full fusion. A possible explanation for these observations is that the TM domain must be a critical length in order for HA to promote full fusion. To test this hypothesis, we analyzed biochemical properties and fusion phenotypes of HA with alterations in its 27–amino acid TM domain. Our mutants included sequential 2–amino acid (Δ2–Δ14) and an 11–amino acid deletion from the COOH-terminal end, deletions of 6 or 8 amino acids from the NH2-terminal and middle regions, and a deletion of 12 amino acids from the NH2-terminal end of the TM domain. We also made several point mutations in the TM domain. All of the mutants except Δ14 were expressed at the cell surface and displayed biochemical properties virtually identical to wild-type HA. All the mutants that were expressed at the cell surface promoted full fusion, with the notable exception of deletions of >10 amino acids. A mutant in which 11 amino acids were deleted was severely impaired in promoting full fusion. Mutants in which 12 amino acids were deleted (from either end) mediated only hemifusion. Hence, a TM domain of 17 amino acids is needed to efficiently promote full fusion. Addition of either the hydrophilic HA cytoplasmic tail sequence or a single arginine to Δ12 HA, the hemifusion mutant that terminates with 15 (hydrophobic) amino acids of the HA TM domain, restored full fusion activity. Our data support a model in which the TM domain must span the bilayer to promote full fusion.
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Wu, Eugene, Lars Pache, Dan J. Von Seggern, Tina-Marie Mullen, Yeshi Mikyas, Phoebe L. Stewart und Glen R. Nemerow. „Flexibility of the Adenovirus Fiber Is Required for Efficient Receptor Interaction“. Journal of Virology 77, Nr. 13 (01.07.2003): 7225–35. http://dx.doi.org/10.1128/jvi.77.13.7225-7235.2003.
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ABSTRACT The adenovirus (Ad) fiber protein mediates Ad binding to the coxsackievirus and Ad receptor (CAR) and is thus a major determinant of viral tropism. The fiber contains three domains: an N-terminal tail that anchors the fiber to the viral capsid, a central shaft region of variable length and flexibility, and a C-terminal knob domain that binds to cell receptors. Ad type 37 (Ad37), a subgroup D virus associated with severe ocular infections, is unable to use CAR efficiently to infect host cells, despite containing a CAR binding site in its fiber knob. We hypothesized that the relatively short, inflexible Ad37 fiber protein restricts interactions with CAR at the cell surface. To test this hypothesis, we analyzed the infectivity and binding of recombinant Ad particles containing modified Ad37 or Ad5 fiber proteins. Ad5 particles equipped with a truncated Ad5 fiber or with a chimeric fiber protein comprised of the Ad5 knob fused to the short, rigid Ad37 shaft domain had significantly reduced infectivity and attachment. In contrast, placing the Ad37 knob onto the long, flexible Ad5 shaft allowed CAR-dependent virus infection and cell attachment, demonstrating the importance of the shaft domain in receptor usage. Increasing fiber rigidity by substituting the predicted flexibility modules in the Ad5 shaft with the corresponding regions of the rigid Ad37 fiber dramatically reduced both virus infection and cell attachment. Cryoelectron microscopy (cryo-EM) single-particle analysis demonstrated the increased rigidity of this chimeric fiber. These studies demonstrate that both length and flexibility of the fiber shaft regulate CAR interaction and provide a molecular explanation for the use of alternative receptors by subgroup D Ad with ocular tropism. We present a molecular model for Ad-CAR interactions at the cell surface that explains the significance of fiber flexibility in cell attachment.