Zeitschriftenartikel: „Simulated body liquid“

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Xu, Huan, Zhi Qiang Li, He Dong, Ya Chao Di und Yang Yang Tang. „Numerical Investigation of the Gas-Liquid Two-Phase Flow around the Square-Section Cylinder Using a Multi-Scale Turbulence Model“. Applied Mechanics and Materials 444-445 (Oktober 2013): 437–45. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.437.

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The upward gas-liquid cross flow around a square cylinder was simulated using two fluid model with the multi-scale turbulent model based on the variable interval time average method. The computational results show that the multi-scale turbulent model can successfully simulate lift coefficient, drag coefficient and vortex shedding characteristics of flow around a body, and can also accurately predict the void fraction distribution and flow structure. Compared with the experimental data, the results of the multi-scale model are better than that of Standard k-ε model and RNG k-ε model. Hence, the study of this paper certificates further that this model can be used in the simulation of the gas-liquid flow around bluff bodies and outher engineering application.

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Yan, Y. Y., Y. Q. Zu, L. Q. Ren und J. Q. Li. „Numerical modelling of electro-osmotically driven flow within the microthin liquid layer near an earthworm surface - a biomimetic approach“. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 221, Nr. 10 (30.09.2007): 1201–10. http://dx.doi.org/10.1243/09544062jmes518.

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The electro-osmotic flow near an earthworm body surface is a basic electrokinetic phenomenon that takes place when the earthworm moves in moist soil. The flow within a microthin liquid layer near earthworm's body surface is induced by the electric double layer (EDL) interaction. Such a microscale electro-osmotic flow plays a role of lubrication between the earthworm's body surface and the surrounding medium of moist soil and reduces surface adhesion. In the current paper, the electro-osmotic flow near earthworm surface is numerically simulated to further understand the mechanism of antisoil adhesion. A lattice Poisson method is first employed to solve electric potential and charge distributions in the EDL along an earthworm surface; the external electric field is then obtained by solving the Laplace equation. The motion of electro-osmotic flow controlled by Navier-Stokes equations is simulated by the lattice Boltzmann method. Typically, the simulation of electro-osmotic flow shows that moving vortices, which likely contribute to antisoil adhesion, can be formed near the earthworm body surface by the non-uniform and variational electrical force.

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Keil, Claudia, Christopher Hübner, Constanze Richter, Sandy Lier, Lars Barthel, Vera Meyer, Raman Subrahmanyam, Pavel Gurikov, Irina Smirnova und Hajo Haase. „Ca-Zn-Ag Alginate Aerogels for Wound Healing Applications: Swelling Behavior in Simulated Human Body Fluids and Effect on Macrophages“. Polymers 12, Nr. 11 (18.11.2020): 2741. http://dx.doi.org/10.3390/polym12112741.

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Chronic non-healing wounds represent a substantial economic burden to healthcare systems and cause a considerable reduction in quality of life for those affected. Approximately 0.5–2% of the population in developed countries are projected to experience a chronic wound in their lifetime, necessitating further developments in the area of wound care materials. The use of aerogels for wound healing applications has increased due to their high exudate absorbency and ability to incorporate therapeutic substances, amongst them trace metals, to promote wound-healing. This study evaluates the swelling behavior of Ca-Zn-Ag-loaded alginate aerogels and their metal release upon incubation in human sweat or wound fluid substitutes. All aerogels show excellent liquid uptake from any of the formulas and high liquid holding capacities. Calcium is only marginally released into the swelling solvents, thus remaining as alginate bridging component aiding the absorption and fast transfer of liquids into the aerogel network. The zinc transfer quota is similar to those observed for common wound dressings in human and animal injury models. With respect to the immune regulatory function of zinc, cell culture studies show a high availability and anti-inflammatory activity of aerogel released Zn-species in RAW 264.7 macrophages. For silver, the balance between antibacterial effectiveness versus cytotoxicity remains a significant challenge for which the alginate aerogels need to be improved in the future. An increased knowledge of the transformations that alginate aerogels undergo in the course of the fabrication as well as during wound fluid exposure is necessary when aiming to create advanced, tissue-compatible aerogel products.

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Shahlori, R., G. I. N. Waterhouse, T. A. Darwish, A. R. J. Nelson und D. J. McGillivray. „Counting crystal clusters – a neutron reflectometry study of calcium phosphate nano-cluster adsorption at the air–liquid Interface“. CrystEngComm 19, Nr. 38 (2017): 5716–20. http://dx.doi.org/10.1039/c7ce01303e.

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Kupershtokh, A. L., E. V. Ermanyuk und N. V. Gavrilov. „The Rupture of Thin Liquid Films Placed on Solid and Liquid Substrates in Gravity Body Forces“. Communications in Computational Physics 17, Nr. 5 (Mai 2015): 1301–19. http://dx.doi.org/10.4208/cicp.2014.m340.

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AbstractThis paper presents a numerical and experimental study on hydrodynamic behavior of thin liquid films in rectangular domains. Three-dimensional computer simulations were performed using the lattice Boltzmann equation method (LBM). The liquid films laying on solid and liquid substrates are considered. The rupture of liquid films in computations is initiated via the thermocapillary (Marangoni) effect by applying an initial spatially localized temperature perturbation. The rupture scenario is found to depend on the shape of the temperature distribution and on the wettability of the solid substrate. For a wettable solid substrate, complete rupture does not occur: a residual thin liquid film remains at the substrate in the region of pseudo-rupture. For a non-wettable solid substrate, a sharp-peaked axisymmetric temperature distribution induces the rupture at the center of symmetry where the temperature is maximal. Axisymmetric temperature distribution with a flat-peaked temperature profile initiates rupture of the liquid film along a circle at some distance from the center of symmetry. The outer boundary of the rupture expands, while the inner liquid disk transforms into a toroidal figure and ultimately into an oscillating droplet.We also apply the LBM to simulations of an evolution of one or two holes in liquid films for two-layer systems of immiscible fluids in a rectangular cell. The computed patterns are successfully compared against the results of experimental visualizations. Both the experiments and the simulations demonstrate that the initially circular holes evolved in the rectangular cell undergoing drastic changes of their shape under the effects of the surface tension and gravity. In the case of two interacting holes, the disruption of the liquid bridge separating two holes is experimentally observed and numerically simulated.

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Zhang, Y. F., B. Hinton, G. Wallace, X. Liu und M. Forsyth. „On corrosion behaviour of magnesium alloy AZ31 in simulated body fluids and influence of ionic liquid pretreatments“. Corrosion Engineering, Science and Technology 47, Nr. 5 (August 2012): 374–82. http://dx.doi.org/10.1179/1743278212y.0000000032.

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Osmanlliu, MDCM, FRCPC, Esli, Ilana Bank, MDCM, FRCPC, FAAP, Elene Khalil, MDCM, FRCPC, FAAP, Peter Nugus, PhD, Margaret Ruddy, RN, BSc Nursing, MMgmt und Meredith Young, PhD. „Decontamination effectiveness and the necessity of innovation in a large-scale disaster simulation“. American Journal of Disaster Medicine 16, Nr. 1 (01.01.2021): 67–73. http://dx.doi.org/10.5055/ajdm.2021.0388.

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Background: Chemical, biological, radiologic, nuclear, and explosive (CBRNE) events threaten the health and integrity of human populations across the globe. Effective decontamination is a central component of CBRNE disaster response.Objective: This paper provides an objective determination of wet decontamination effectiveness through the use of a liquid-based contaminant proxy and describes the mobilization and adaptation of easily available materials for the needs of decontamination in pediatric victims.Methods: In this in-situ disaster simulation conducted at a pediatric hospital, decontamination effectiveness was determined through a liquid-based contaminant proxy, and standard burn charts to systematically estimate affected total body surface area (TBSA) in 39 adult simulated patients. Two independent raters evaluated TBSA covered by the contaminant before and after decontamination.Results: On average, simulated patients had 59 percent (95 percent CI [53, 65]) of their TBSA covered by the simulated contaminant prior to decontamination. Following a wet decontamination protocol, the average reduction in TBSA contamination was 81 percent (95 percent CI [74, 88]). There was high inter-rater reliability for TBSA assessment (intraclass correlation coefficient = 0.83, 95 percent CI [0.68, 0.92]. A modified infant bath was tested during the simulated decontamination of infant mannequins and thereafter integrated to the local protocol.Conclusion: Wet decontamination can remove more than 80 percent of the initial contaminant found on adult simulated patients. The use of a liquid-based visual tool as a contaminant proxy enables the inexpensive evaluation of decontamination performance in a simulated setting. This paper also describes an innovative, low-cost adaptation of a local decontamination protocol to better meet pediatric needs.

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Badr, Ahmed Noah, Karolina Gromadzka, Mohamed Gamal Shehata, Kinga Stuper-Szablewska, Kinga Drzewiecka und Adel Gabr Abdel-Razek. „Prospective antimycotoxigenic action of wild Opuntia ficus-indica by-products“. Czech Journal of Food Sciences 38, No. 5 (30.10.2020): 308–14. http://dx.doi.org/10.17221/11/2020-cjfs.

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Numerous natural compounds perform pharmaceutical, antimycotic and antitoxic purposes in the body system. The aim was to evaluate new phytoconstituents that provide antimycotoxigenic properties against mycotoxins. Bioactive materials chosen were fruit peels and cladodes of wild Opuntia ficus-indica containing a measurable quantity of bioactive phytochemicals. The highest concentration of bioactive metabolites was recorded for protocatechuic and t-cinnamic acids. A reduction effect of bioactives was estimated against aflatoxins, ochratoxin A and zearalenone in a simulated body system. Antifungal activity was determined in liquid media to evaluate antimycotic properties. Lyophilised extracts caused an aflatoxin reduction in media by 14.65% to 23.77% for fruit peels and cladodes, respectively. It caused a decrease of 59% zearalenone and 51% of ochratoxin A in a in a simulated body fluid. The cladode extract manifested better antimycotic and antimycotoxigenic characteristics due to its bioactive contents. These results support a modern antimycotoxin trend of food preservation that has a considerable impact on food safety.

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Franco, C. M. R., A. G. Barbosa de Lima, J. V. Silva und A. G. Nunes. „Applying Liquid Diffusion Model for Continuous Drying of Rough Rice in Fixed Bed“. Defect and Diffusion Forum 369 (Juli 2016): 152–56. http://dx.doi.org/10.4028/www.scientific.net/ddf.369.152.

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Simulate the rice drying process at specific drying conditions is of great interest to optimize the process and ensure a better quality of the final product. In the present work, experimental drying procedures of rough rice grains (BRSMG CONAI variety) was reported and drying kinetic was obtained at temperature using 40°C. The results were compared with simulated data by means of the liquid diffusion model equilibrium boundary condition. The geometry used to represent the rice grain was prolate spheroid. For this purpose, the diffusion equation, written in cylindrical coordinates, and solved via Galerkin-based integral method considering the constant diffusion coefficient. A good agreement was observed between predicted and experimental data. It was also possible to observe that the highest moisture gradients occur at the tip of the grain, which is region more affected by thermal and hydric stresses. The studied model can be used to solve problems involving diffusion processes, such as: drying, wetting, heating and cooling, provided that the geometrical shape of the body is similar to prolate spheroid.

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Nguyen, Van Thuan, und Chang Won Jung. „Impact of Dielectric Constant on Embedded Antenna Efficiency“. International Journal of Antennas and Propagation 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/758139.

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The impact of dielectric constant on radiation efficiency of embedded antenna located inside human body or another liquid environment is investigated both analytically and numerically. Our research is analysed and simulated at 403 MHz in the MedRadio band (401–406 MHz) and within a block of 2/3 human muscle phantom. Good agreement is achieved between analysis and simulation results. This work provides a guidance in selecting insulator for embedded antennas.

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Ashok Kumar, Srinivasan, und Thangavelu Shanmuganantham. „Implantable CPW-fed Z-monopole antennas at 2.45 GHz ISM band for biomedical applications“. International Journal of Microwave and Wireless Technologies 7, Nr. 5 (09.06.2014): 529–33. http://dx.doi.org/10.1017/s1759078714000725.

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A novel coplanar waveguide-fed Z-monopole antennas are proposed for the first time for a industrial, scientific, and medical (ISM) band (2.4–2.48 GHz) applications. To make the designed antenna suitable for implantation, it is embedded in biocompatible Al2O3ceramic substrate. The antenna operates at resonance frequency of 2.45 GHz to support wide band communication for high data rate implantable neural monitoring application. The size of the antenna is 38.675 mm3(8.5 mm × 7 mm × 0.65 mm). The antenna was simulated and measured by immersing it in a phantom liquid, imitate the electrical properties of the human body phantom liquid. The simulated and measured bandwidths are 10.2 and 11.4% at the centre frequency. A study of the sensitivity of the antenna performance as a function of its dielectric parameters of the environment in which it is immersed was performed. The demonstration among the design EM characteristics of the antenna is presented by current distributions.

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Huang, C. H., J. J. Lai, T. Y. Wei, Y. H. Chen, X. Wang, S. Y. Kuan und J. C. Huang. „Improvement of bio-corrosion resistance for Ti42Zr40Si15Ta3 metallic glasses in simulated body fluid by annealing within supercooled liquid region“. Materials Science and Engineering: C 52 (Juli 2015): 144–50. http://dx.doi.org/10.1016/j.msec.2015.03.056.

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Ma, Hong Yun, Zhen Hong Zhao, Dong Wang, Jun Zhang, Li Guo und Zhi Jun Li. „Research Progress of Fractionation Mechanism of Stable Hydrogen and Oxygen Isotope during Water Body Evaporation“. Advanced Materials Research 550-553 (Juli 2012): 2588–92. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.2588.

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Evaporation is the most significant process that affects the isotopic transport of surface water. The study of mechanisms and modeling of the evaporation process has a very important practical significance in improving the isotopic analysis method. This paper reviews the international development of the mechanism of hydrogen and oxygen stable isotopic fractionation and model. It indicates that as the most ideal tracers of hydrologic cycle, stable hydrogen and oxygen isotopes have their unique and irreplaceable functions. However, field experiments of evaporation and further research are limited by the complexities of kinetic flow in the atmosphere and observation technique. Modeling and experiments are commonly based on the assumption that evaporating water is well-mixed, and isotopic stratification in liquid is not considered by most laboratories. While it dose affect. Flow disturbance in the atmosphere is the most uncertain factor for isotopic fractionation in the process of evaporation. The modeling example shows isotopic evaporation line of natural water can be simulated properly while detailed simulations are limited by the lake of observational data of isotopic diffusion processes in both air phase and liquid phase.

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Ploszajski, Anna R., Richard Jackson, Mark Ransley und Mark Miodownik. „4D Printing of Magnetically Functionalized Chainmail for Exoskeletal Biomedical Applications“. MRS Advances 4, Nr. 23 (2019): 1361–66. http://dx.doi.org/10.1557/adv.2019.154.

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AbstractChainmail fabrics manufactured by selective laser sintering 3D printing have been magnetically functionalized to create a lightweight, 4D printed, actuating fabric. The post-processing method involves submerging the porous prints in commercial ferrofluid (oil-based magnetic liquid), followed by drying under heat. The actuation of the chainmail has been simulated using a rigid multi-body physics engine, and qualitatively matches experiment. Such magnetically actuating fabrics have potential to make thin, lightweight and comfortable wearable assistive devices.

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Dwiyantoro, Bambang Arip. „Numerical Study of Droplet Formation Time on Solid Surface“. Advanced Materials Research 683 (April 2013): 820–23. http://dx.doi.org/10.4028/www.scientific.net/amr.683.820.

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Microdroplets on solid surface are very common phenomenon in many engineering applications. The microdroplet formed from the fluid remaining on the column of micropillar after dewetting process. In this study, we generated microdroplet with various patterns and simulated the microfluidic dynamic processes based on a deforming body-fitted grid approach. The simulation results provide for explaining the effects of Capillary number and the liquid thickness on micropillar surface in the growing droplet diameter and microdroplet formation time.

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URRUTIA-BAÑUELOS, EFRAÍN, und ALVARO POSADA-AMARILLAS. „STRUCTURAL AND DYNAMICAL PROPERTIES IN LIQUID Ni AND Ag BY COMPUTER SIMULATION“. International Journal of Modern Physics B 17, Nr. 07 (20.03.2003): 1011–25. http://dx.doi.org/10.1142/s0217979203018132.

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We studied the temperature dependence of the structural and dynamical properties for liquid nickel and silver by modeling the interatomic interaction through a tight-binding n-body potential in the second-moment approximation (TB-SMA). A common-neighbor analysis was performed to explore the microstructural changes with temperature in Ni and Ag in the liquid state in terms of their inherent structures (IS). A tendency to the formation of more symmetric IS characteristic of the BCC crystalline and icosahedral order is observed as the temperature is raised. At the same time, the FCC and HCP crystalline order is reduced while the BCC-type order increases. The simulated diffusion coefficients are in reasonable agreement with the available experimental information and with other theoretical results. The simple liquid behavior is shown by an Arrhenius plot for both nickel and silver.

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Pakpoom, Supachart, Kruakaew Prarop, Swasdisevi Thanit und Wongsarivej Pratarn. „Effect of Vortex Finder, Inlet and Body Diameter on Separation Efficiency of Hydrocyclone for Crude Palm Oil Industry“. Key Engineering Materials 659 (August 2015): 652–58. http://dx.doi.org/10.4028/www.scientific.net/kem.659.652.

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Hydrocyclone is novel optional equipment that can be applied in solid separation for crude palm oil process because of its advantage over the existing technology. Hydrocyclone is a cost-effective, continuous tool which is easy for maintenance. The objective of this research is to investigate the effect of vortex finder, inlet, and body diameter of hydrocyclone on separation efficiency of palm meal from crude palm oil by using PVC resin as the solid phase and biodiesel B5 as the liquid phase. All parameters were simulated using computational fluid dynamic, CFD. In addition, the inlet diameters were tested experimentally. The feed flow rates in both simulation and experiment were varied from 4 - 14 L/min at the constant flow ratio of 0.2. Experimental design was clearly specified. The vortex finder diameters of 3.8, 4.8, and 5.8 mm were also simulated as well as the inlet diameters of 5, 6, and 7 mm. Three sizes of body diameter of 30, 40, and 50 mm were selected as the example sizes. According to the simulation results, the smaller vortex finder, inlet, and body diameter of hydrocyclone revealed the higher separation efficiency.

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Xu, Hui, Xiao Hong Chen und Yao Yao. „Hydrocyclone Velocity Flow Simulation and Experimental Study Based on Fluid Mechanics“. Advanced Materials Research 625 (Dezember 2012): 113–16. http://dx.doi.org/10.4028/www.scientific.net/amr.625.113.

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The strong swirl turbulent flow in hydrocyclone causes major difficulties in modeling their internal solid-liquid flows. In this thesis, the strongly swirling turbulent flow in solid-liquid hydrocyclone separators is simulated by using Reynolds stress equation models (RSM) of FLUENT applications to use the body-fitted and partition meshes. The results give some new understanding on 3D velocity distribution. According to the numerical simulation results, the lab experiment is implemented in this thesis.the lab simulation system and real-time data process system are set up to gather the parameters in the simulation system. the relation curve of production capacity-inlet pressure and separation property-inlet pressure are analyzed. Comparing with the numerical simulation ,the result is reasonable.

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Yang, Yang, Ya Hua Qiao, Xin Yi Pan, Yong Ye Liu, Fu Dong Liu, Ai Ling Zhang, Bo Wang und Chun Ming Zhang. „Research of Water Body Diffusion Condition in Near Field of Inland Nuclear Power Plants in China“. Advanced Materials Research 955-959 (Juni 2014): 1722–25. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.1722.

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With the increase in demand for electricity in inland provinces because of economic growth, construction of inland nuclear power plant (npp) has become a trend. Inland npps discharge into the water bodies where may be some drinking water sources downstream, so the impact of radioactive liquid effluent released from inland npps is far greater than that come from coastal npps, and it is necessary to know the hydrodynamic characteristics of the water bodies clearly. A proposed inland npp near the Yangtze River and another near a reservoir were simulated by Cormix respectively. Then analyse the simulation results and suggest to use diffusers to help to initial mixing of contaminants in near field.

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Zhong, Xiao Chun, Wei Ke Qin und Hai Wang. „Test of Solidification Characteristics of Grouting and the Effect on Strata Deformation in Shield Tunnelling“. Advanced Materials Research 568 (September 2012): 80–84. http://dx.doi.org/10.4028/www.scientific.net/amr.568.80.

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Back-fill Grouting is a key procedure for the active control of strata settlement during shield tunnelling in civil engineering. The paper studies the stress - strain characteristics of grouting and the state of grout, which changes from liquid to solid over time and is simulated by variable rigid body. The model of flowing state are divided in four phases from liquid-plastic to rigid state. The paper establish a numerical model of shield tunnelling in civil engineering with the consideration of characteristics of grout deformation, and has analyzed law of strata settlement. The test results show that the calculation method can well accord with the four stages of strata deformation, and can more accurately reflect the process of strata deformation caused by shield tunneling.

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Dorner-Reisel, A., G. Gärtner, G. Reisel und G. Irmer. „Diamond-like carbon films for polyethylene femoral parts: Raman and FT-IR spectroscopy before and after incubation in simulated body liquid“. Analytical and Bioanalytical Chemistry 390, Nr. 6 (22.12.2007): 1487–93. http://dx.doi.org/10.1007/s00216-007-1744-7.

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Bao, Yangjuan, Yu Huang, G. R. Liu und Wei Zeng. „SPH Simulation of High-Volume Rapid Landslides Triggered by Earthquakes Based on a Unified Constitutive Model. Part II: Solid–Liquid-Like Phase Transition and Flow-Like Landslides“. International Journal of Computational Methods 17, Nr. 04 (29.11.2019): 1850149. http://dx.doi.org/10.1142/s0219876218501499.

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High-volume fast-moving landslides undergo a solid–liquid-like phase transition. In this study we apply the smoothed particle hydrodynamics (SPH) method to simulate the solid–liquid-like phase transition in earthquake-induced landslides based on a unified constitutive model. The feasibility analysis is carried out from two aspects: the governing equations in SPH and the unified constitutive model. A sand-collapse experiment simulating the fluidization motion is performed to verify the SPH model. Strong similarities between the SPH results and the experimental results are observed, confirming that the motion of geo-materials in different states can be simulated by the unified constitutive model. The entire process of the Tangjiashan landslide is reproduced. The SPH simulation shows that during the initiation process, the sliding-mass velocity was low as the geo-materials were in solid state. As shown in Part I of this study, a continuous slip surface formed at about 15[Formula: see text]s. The sliding body gains speed as it enters the fluid state. About 50[Formula: see text]s later, the mass gradually stops moving, reaches a steady state and returns to a solid phase. Besides, the SPH simulation based on elastic–plastic model clearly shows the advantage of the proposed model.

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Xu, G. D., W. Y. Duan und G. X. Wu. „Simulation of water entry of a wedge through free fall in three degrees of freedom“. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 466, Nr. 2120 (24.02.2010): 2219–39. http://dx.doi.org/10.1098/rspa.2009.0614.

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The water entry problem of a wedge through free fall in three degrees of freedom is studied through the velocity potential theory for the incompressible liquid. In particular, the effect of the body rotation is taken into account, which seems to have been neglected so far. The problem is solved in a stretched coordinate system through a boundary element method for the complex potential. The impact process is simulated based on the time stepping method. Auxiliary function method has been used to decouple the mutual dependence between the body motion and the fluid flow. The developed method is verified through results from other simulation and experimental data for some simplified cases. The method is then used to undertake extensive investigation for the free fall problems in three degrees of freedom.

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Louzguine-Luzgin, Dmitri V., und Andrey I. Bazlov. „Crystallization of FCC and BCC Liquid Metals Studied by Molecular Dynamics Simulation“. Metals 10, Nr. 11 (18.11.2020): 1532. http://dx.doi.org/10.3390/met10111532.

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The atomic structure variations on cooling, vitrification and crystallization processes in liquid metals face centered cubic (FCC) Cu are simulated in the present work in comparison with body centered cubic (BCC) Fe. The process is done on continuous cooling and isothermal annealing using a classical molecular-dynamics computer simulation procedure with an embedded-atom method potential at constant pressure. The structural changes are monitored with direct structure observation in the simulation cells containing from about 100 k to 1 M atoms. The crystallization process is analyzed under isothermal conditions by monitoring density and energy variation as a function of time. A common-neighbor cluster analysis is performed. The results of thermodynamic calculations on estimating the energy barrier for crystal nucleation and a critical nucleus size are compared with those obtained from simulation. The differences in crystallization of an FCC and a BCC metal are discussed.

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Pan, Kai, und Dengqing Cao. „Absolute nodal coordinate finite element approach to the two-dimensional liquid sloshing problems“. Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 234, Nr. 2 (25.02.2020): 322–46. http://dx.doi.org/10.1177/1464419320907785.

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Two-dimensional large-amplitude liquid sloshing in the rectangular rigid container is numerically simulated through absolute nodal coordinate finite element method, which can describe the large deformation of continuum by using a small number of elements. The incompressible constraint of Newtonian fluid is imposed by the penalty function method. Furthermore, the motion of rigid container is described by absolute nodal coordinate reference node and the liquid kinetic equations are derived in the total Lagrangian formulation, which can easily be combined with the solid nonlinear finite element and the multi-body system algorithms. The free sliding and non-penetrating boundary constraint equations for rectangular tank are derived. To ensure the stability and the conservation of the solution in long time simulations, the system dynamic equations are solved by Bathe integral scheme. Three numerical examples are used to verify the effectiveness of the proposed method, including the free spreading of a square liquid column and the large amplitude sloshing of liquid under rotational and horizontal excitations. A good consistency is obtained by comparing the calculated results with experimental and other numerical results reported in the literature.

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Luo, Sheng Lei, Zhan Hua Yang, Ming Lin, Xin Xu, Yan Hui Zhang, Bin Guo und Li Li Dong. „Characterization and Bioactivity of Ti-6Al-4V Alloy Dental Implant Surface Treated by SLA Technique“. Advanced Materials Research 926-930 (Mai 2014): 965–68. http://dx.doi.org/10.4028/www.scientific.net/amr.926-930.965.

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Superior quality dental implant surface was achieved by an air-isolation technique of sand-blasted, large-grit, acid-etched (SLA) treatment. The experiment was conducted in an air-isolation conditions of sand-blasting and acid-etching. The surface microstructures, chemical compositions, and bioactive properties of treated Ti-6Al-4V implants were examined using scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and simulated body fluid (SBF) immersion test. Research results revealed that the air-isolation SLA (A-SLA) treated implant, which was coated with SBF thin liquid film and sandblasted for 20 s, exhibited better hydroxyapatite (HA)-inducing ability owing to its favorable wettability.

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He, Xiang Li, Yu Tong Jiang und Mao Ye. „The Effects of Saturated Sediment Layer on Seismic Wave Motion of Gravity Dams“. Applied Mechanics and Materials 744-746 (März 2015): 1151–56. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.1151.

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Sediment layer can change the dynamic property of reservoir water. As a result, the dynamic response of dam body would be affected. In this paper, the sediment layer is simulated as saturated liquid-solid two-phase media, and the finite element model of gravity dam-reservoir water-sediment system is established with the gradual enlargement mesh method. Then the influence of sediment layer on seismic wave motion is studied with this model. The calculation result shows that the energy radiation of far field of foundation, reservoir water and sediment can be considered efficiently in this model, and with the thickening of sediment layer the dynamic water pressure on dam face decreases.

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Ładniak, Agata, Małgorzata Jurak und Agnieszka Ewa Wiącek. „Wettability of DPPC Monolayers Deposited from the Titanium Dioxide–Chitosan–Hyaluronic Acid Subphases on Glass“. Colloids and Interfaces 3, Nr. 1 (23.01.2019): 15. http://dx.doi.org/10.3390/colloids3010015.

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The investigations were carried out to determine wettability of the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers transferred from the liquid subphases containing chitosan (Ch), hyaluronic acid (HA), and/or titanium dioxide (TiO2) to a glass support by means of the Langmuir–Blodgett (LB) technique. For comparative purposes, the analysis of the plates surfaces emerged from the analogous subphases without the phospholipid film was also made. Characterization of the DPPC monolayers was based on the contact angle measurements using three test liquids (water, formamide, diiodomethane) and a simulated body fluid (SBF) solution in which the concentration of ions was close to that of human plasma. After deposition of the DPPC monolayers on the glass plates, a significant increase in the contact angles of all the probe liquids was observed compared to the plates pulled out from the given subphase without floating DPPC. The presence of phospholipid monolayer increased the hydrophobic character of the surface due to orientation of its molecules with hydrocarbon chains towards the air. In addition, the components of the subphase attached along with DPPC to the glass support modify the surface polarity. The largest changes were observed in the presence of TiO2.

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Wang, Haiyang, Toshinari Maeda und Toshiki Miyazaki. „Preparation of bioactive and antibacterial PMMA-based bone cement by modification with quaternary ammonium and alkoxysilane“. Journal of Biomaterials Applications 36, Nr. 2 (24.03.2021): 311–20. http://dx.doi.org/10.1177/08853282211004413.

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Bone cement based on poly(methyl methacrylate) (PMMA) powder and methyl methacrylate (MMA) liquid is a very popular biomaterial used for the fixation of artificial joints. However, there is a risk of this cement loosening from bone because of a lack of bone-bonding bioactivity. Apatite formation in the body environment is a prerequisite for cement bioactivity. Additionally, suppression of infection during implantation is required for bone cements to be successfully introduced into the human body. In this study, we modified PMMA cement with γ-methacryloxypropyltrimetoxysilane and calcium acetate to introduce bioactive properties and 2-( tert-butylamino)ethyl methacrylate (TBAEMA) to provide antibacterial properties. The long-term antibacterial activity is attributed to the copolymerization of TBAEMA and MMA. As the TBAEMA content increased, the setting time increased and the compressive strength decreased. After soaking in simulated body fluid, an apatite layer was detected within 7 days, irrespective of the TBAEMA content. The cement showed better antibacterial activity against Gram-negative E. Coli than Gram-positive bacteria; however, of the Gram-positive bacteria investigated, B. subtilis was more susceptible than S. aureus.

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Sultan, Saira, Cindy Giles, Gabriele Netzel, Simone Osborne, Michael Netzel und Mary Fletcher. „Release of Indospicine from Contaminated Camel Meat following Cooking and Simulated Gastrointestinal Digestion: Implications for Human Consumption“. Toxins 10, Nr. 9 (03.09.2018): 356. http://dx.doi.org/10.3390/toxins10090356.

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Indospicine, a hepatotoxic arginine analog, occurs in leguminous plants of the Indigofera genus and accumulates in the tissues of grazing animals that consume these plants. Furthermore, indospicine has caused toxicity in dogs following consumption of indospicine-contaminated meat; however, the potential impact on human health is unknown. The present study was designed to determine the effect of simulated human gastrointestinal digestion on the release and degradation of indospicine from contaminated camel meat following microwave cooking. Results showed no significant (p > 0.05) indospicine degradation during cooking or in vitro digestion. However, approximately 70% indospicine was released from the meat matrix into the liquid digesta during the gastric phase (in the presence of pepsin) and increased to >90% in the intestinal phase (with pancreatic enzymes). Following human consumption of contaminated meat, this soluble and more bioaccessible fraction of intact indospicine could be readily available for absorption by the small intestine, potentially circulating indospicine throughout the human body to tissues where it could accumulate and cause detrimental toxic effects.

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Song, Yu-Lin, Chih-Hsiao Cheng, Manoj Kumar Reddy und Md Saikhul Islam. „Simulation of Onset of the Capillary Surface Wave in the Ultrasonic Atomizer“. Micromachines 12, Nr. 10 (23.09.2021): 1146. http://dx.doi.org/10.3390/mi12101146.

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The novel drug delivery system refers to the formulations and technologies for transporting a pharmaceutical compound in the body as it is needed to safely achieve its desired therapeutic effects. In this study, the onset vibrational amplitude of capillary surface waves for ultrasonic atomization spray is explained based on Faraday instability. Using ultrasonic frequency, the vibrational amplitude approached a critical point, and the liquid surface broke up into tiny drops. The micro-droplets were are steadily and continuously formed after the liquid feeding rate was optimized. The simulation study reported a minimum vibrational amplitude or onset value of 0.38 μm at 500 kHz frequency. The required minimum energy to atomize the drops was simulated by COMSOL Multiphysics simulation software. The simulation result agreed well with the numerical results of a subharmonic vibrational model that ocurred at 250 kHz frequency on the liquid surface. This newly designed single frequency ultrasonic atomizer showed its true physical characteristic of resonance on the fluid surface plane. Hence, this research will contribute to the future development of a single-frequency ultrasonic nebulizer and mechatronics for the generation of uniform atomized droplets.

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Moyo, Siphosanele Mafa, June C. Serem, Megan J. Bester, Vuyo Mavumengwana und Eugenie Kayitesi. „Hydrothermal Processing and In Vitro Simulated Human Digestion Affects the Bioaccessibility and Bioactivity of Phenolic Compounds in African Pumpkin (Momordica balsamina) Leaves“. Molecules 26, Nr. 17 (27.08.2021): 5201. http://dx.doi.org/10.3390/molecules26175201.

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The African pumpkin (Momordica balsamina) contains bioactive phenolic compounds that may assist in reducing oxidative stress in the human body. The leaves are mainly consumed after boiling in water for a specific time; this hydrothermal process and conditions of the gastrointestinal tract may affect the presence and bioactivity of phenolics either positively or negatively. In this study, the effects of hydrothermal processing (boiling) and in vitro simulated human digestion on the phenolic composition, bioaccessibility and bioactivity in African pumpkin were investigated in comparison with those of spinach (Spinacia oleracea). A high-resolution ultra-performance liquid chromatography, coupled with diode array detection, quadrupole time-of-flight and mass spectrometer (UPLC-DAD-QTOF-MS) was used to profile phenolic metabolites. Metabolites such as 3-caffeoylquinic acid, 5-caffeoylquinic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid were highly concentrated in the boiled vegetable extracts compared to the raw undigested and all digested samples. The majority of African pumpkin and spinach extracts (non-digested and digested) protected Deoxyribonucleic acid (DNA), (mouse fibroblast) L929 and human epithelial colorectal adenocarcinoma (Caco-2) cells from 2,2′-Azobis(2-methylpropionamidine) dihydrochloride (AAPH)-induced oxidative damage. From these results, the consumption of boiled African pumpkin leaves, as well as spinach, could be encouraged, as bioactive metabolites present may reduce oxidative stress in the body.

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Colovic, Bozana, Dejan Markovic und Vukoman Jokanovic. „Nucleation of biomimetic hydroxyapatite“. Serbian Dental Journal 58, Nr. 1 (2011): 7–15. http://dx.doi.org/10.2298/sgs1101007c.

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Introduction. The aim of the study was to assess the formation of biomimetic calcium hydroxyapatite (HAP) on the surface of different substrates. Material and Methods. Silica coated stainless steel tapes and thin polymer films (alginate, cellulose, poly lactide-co-glycolide - PLGA) deposited on hydroxyapatite scaffold were used as substrate. Supersaturated simulated body fluid (SBF) and SBF combined with Fetal Calf Serum (FCS) or Eagle?s Minimum Essential Medium (EMEM) were used as bioactive liquid medium where biomimetic nucleation of HAP occurred. Infrared spectroscopy with Fourier transformation was used to analyze the formed phases, while scanning electron microscopy indicated the morphology of nucleated phase. Results. The results of measuring the mass with volume adjustments done by the BET method showed that the thickness of the film of nucleated calcium hydroxyapatite depended on the time that samples spent soaked in SBF-in as well as the type of selected biomimetic medium. Conclusion. Biomimetic calcium hydroxyapatite is possible to produce by self nucleation on different substrates in the presence of simulating body fluid.

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Momper, Jeremiah D., Edmund V. Capparelli, Kelly C. Wade, Anand Kantak, Ramasubbareddy Dhanireddy, James J. Cummings, Jonathan H. Nedrelow et al. „Population Pharmacokinetics of Fluconazole in Premature Infants with Birth Weights Less than 750 Grams“. Antimicrobial Agents and Chemotherapy 60, Nr. 9 (11.07.2016): 5539–45. http://dx.doi.org/10.1128/aac.00963-16.

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ABSTRACTFluconazole is an effective agent for prophylaxis of invasive candidiasis in premature infants. The objective of this study was to characterize the population pharmacokinetics (PK) and dosing requirements of fluconazole in infants with birth weights of <750 g. As part of a randomized clinical trial, infants born at <750 g birth weight received intravenous (i.v.) or oral fluconazole at 6 mg/kg of body weight twice weekly. Fluconazole plasma concentrations from samples obtained by either scheduled or scavenged sampling were measured using a liquid chromatography-tandem mass spectrometry assay. Population PK analysis was conducted using NONMEM 7.2. Population PK parameters were allometrically scaled by body weight. Covariates were evaluated by univariable screening followed by multivariable assessment. Fluconazole exposures were simulated in premature infants using the final PK model. A population PK model was developed from 141 infants using 604 plasma samples. Plasma fluconazole PK were best described by a one-compartment model with first-order elimination. Only serum creatinine was an independent predictor for clearance in the final model. The typical population parameter estimate for oral bioavailability in the final model was 99.5%. Scavenged samples did not bias the parameter estimates and were as informative as scheduled samples. Simulations indicated that the study dose maintained fluconazole troughs of >2,000 ng/ml in 80% of simulated infants at week 1 and 59% at week 4 of treatment. Developmental changes in fluconazole clearance are best predicted by serum creatinine in this population. A twice-weekly dose of 6 mg/kg achieves appropriate levels for prevention of invasive candidiasis in extremely premature infants.

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Weise, Philipp, Gábor A. Czirják, Oliver Lindecke, Sara Bumrungsri und Christian C. Voigt. „Simulated bacterial infection disrupts the circadian fluctuation of immune cells in wrinkle-lipped bats (Chaerephon plicatus)“. PeerJ 5 (03.08.2017): e3570. http://dx.doi.org/10.7717/peerj.3570.

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BackgroundLeukocyte concentrations follow a circadian pattern in mammals, with elevated values at times of potential contact with pathogens and parasites. We hypothesized that this pattern is disturbed after an immune challenge.MethodsIn Thailand, we captured wrinkle-lipped bats (Chaerephon plicatus), when they returned to their colony at dawn. We challenged half of the animals (experimental group) with bacterial lipopolysaccharides and treated the others only with the carrier liquid (control group). We then compared body mass changes and differences in circulating immune cell counts at 8 h post-treatment.ResultsIn experimental animals, we observed an increase in total leukocyte and neutrophil numbers of 17% and 95%, respectively. In control animals, concentrations of leukocytes decreased by 44% and those of neutrophils remained constant. Experimental treatment had no effect on lymphocytes, yet changes in eosinophil numbers were explained by sex. Eosinophils decreased by 66% in females and by 62% in males. Basophils and monocytes were rarest among all observed cell types and analysis was either impossible because of low numbers or yielded no significant effects, respectively.DiscussionOur findings show that a simulated bacterial infection triggered a neutrophil-associated immune response in wrinkle-lipped bats, indicating a disruption of the diurnal fluctuation of immune cells. Our study suggests that bats exhibit circadian rhythms in immune cell counts. The magnitude of these fluctuations may vary across species according to specific-specific infection risks associated with colony sizes or specific roosting habits.

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Trzcińska, Zuzanna, Marc Bruggeman, Hanieh Ijakipour, Nikolas J. Hodges, James Bowen und Artemis Stamboulis. „Polydopamine Linking Substrate for AMPs: Characterisation and Stability on Ti6Al4V“. Materials 13, Nr. 17 (22.08.2020): 3714. http://dx.doi.org/10.3390/ma13173714.

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Infections are common complications in joint replacement surgeries. Eradicated infections can lead to implant failure. In this paper, analogues of the peptide KR-12 derived from the human cathelicidin LL-37 were designed, synthesised, and characterised. The designed antimicrobial peptides (AMPs) were attached to the surface of a titanium alloy, Ti6Al4V, by conjugation to a polydopamine linking substrate. The topography of the polydopamine coating was evaluated by electron microscopy and coating thickness measurements were performed with ellipsometry and Atomic Force Microscopy (AFM). The subsequently attached peptide stability was investigated with release profile studies in simulated body fluid, using both fluorescence imaging and High-Performance Liquid Chromatography (HPLC). Finally, the hydrophobicity of the coating was characterised by water contact angle measurements. The designed AMPs were shown to provide long-term bonding to the polydopamine-coated Ti6Al4V surfaces.

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Funazaki, K., M. Yokota und S. Yamawaki. „Effect of Periodic Wake Passing on Film Effectiveness of Discrete Cooling Holes Around the Leading Edge of a Blunt Body“. Journal of Turbomachinery 119, Nr. 2 (01.04.1997): 292–301. http://dx.doi.org/10.1115/1.2841112.

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Detailed studies are conducted on film effectiveness of discrete cooling holes around the leading edge of a blunt body that is subjected to periodically incoming wakes as well as free-stream turbulence with various levels of intensity. The cooling holes have a configuration similar to that of typical turbine blades except for the spanwise inclination angle. Secondary air is heated so that the temperature difference between the mainstream and secondary air is about 20 K. In this case, the air density ratio of the mainstream and secondary air becomes less than unity, therefore the flow condition encountered in an actual aero-engine cannot be simulated in terms of the density ratio. A spoke-wheel type wake generator is used in this study. In addition, three types of turbulence grids are used to elevate the free-stream turbulence intensity. We adopt three blowing ratios of the secondary air to the mainstream. For each of the blowing ratios, wall temperatures around the surface of the test model are measured by thermocouples situated inside the model. The temperature is visualized using liquid crystals in order to obtain qualitative information of film effectiveness distribution.

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Keil, Radan, Štěpán Hlava, Petr Stanovský, Vladimír Ždímal, Jan Šťovíček, Milan Trojánek, Jiří Drábek, Barbora Frýbová, Vojtěch Petráček und Martin Wasserbauer. „Commonly available but highly effective protection against SARS-CoV-2 during gastrointestinal endoscopies“. PLOS ONE 16, Nr. 7 (23.07.2021): e0254979. http://dx.doi.org/10.1371/journal.pone.0254979.

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Background and aims SARS-CoV-2 is a worldwide serious health problem. The aim of this study was to demonstrate the number of potentially infectious particles present during endoscopic procedures and find effective tools to eliminate the risks of SARS-CoV-2 infection while performing them. Methods An experimental model which focused on aerosol problematics was made in a specialized laboratory. This model simulated conditions present during endoscopic procedures and monitored the formation of potentially infectious fluid particles from the patient’s body, which pass through the endoscope and are then released into the environment. For this reason, we designed and tested a prototype of a protective cover for the endoscope’s control body to prevent the release and spread of these fluid particles from its working channel. We performed measurements with and without the protective cover of the endoscope’s control body. Results It was found that liquid coming through the working channel of the endoscope with forceps or other instruments inside generates droplets with a diameter in the range of 0.1–1.1 mm and an initial velocity of up to 0.9 m/s. The average number of particles per measurement per whole measured area without a protective cover on the endoscope control body was 51.1; with this protective cover on, the measurement was 0.0, p<0.0001. Conclusions Our measurements proved that fluid particles are released from the working channel of an endoscope when forceps are inserted. A special protective cover for the endoscope control body, made out of breathable material (surgical cap) and designed by our team, was found to eliminate this release of potentially infectious fluid particles.

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Zhu, Sheng, Feng Liang Yin, Jian Liu und Yuan Yuan Liang. „A Three-Dimensional Model of Droplet Impinging, Solidification and Suspension on the Substrate“. Advanced Materials Research 346 (September 2011): 222–27. http://dx.doi.org/10.4028/www.scientific.net/amr.346.222.

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A three-dimensional model was built to study a molten metal droplet impact on an edge of the substrate in droplet deposition manufacturing process for the first time. The whole calculation domain, including the substrate, was described using same fluid conservation equations, which is to say that the remolding and solidification of substrate was considered also. Droplet free surface was tracked by volume-of-fluid (VOF) algorithm. The effect of surface tension on the droplet was taken into consideration by means of considering surface tension to be a component of the body force. The simulated results show that the droplet in liquid phase can keep suspending on the substrate at a role of surface tension. A too high impact velocity would make parts of droplet splash away the substrate which is not allowed in manufacturing process. The offset between edge of droplet and side edge of substrate influences dramatically the impact of the droplet.

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Chen, Ling, Hong Xiang, Xiao Xi Li, Jian Dong Ye, Xiu Peng Wang und Lin Li. „Improvement of Anti-Washout Performance of Calcium Phosphate Cement Using Modified Starch“. Key Engineering Materials 336-338 (April 2007): 1628–31. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.1628.

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Calcium phosphate cements (CPCs) are well-known orthopedic materials for filling bone. However, CPC pastes tend to disintegrate immediately when contacting with blood or other aqueous (body) fluids, which is a main limitation of its clinical applications in bone repairing, reconstruction and augmentation. To improve the anti-washout performance of CPC, modified starches such as pre-gelatinized starch, etherified starch, and esterified starch were added to the liquid phase of CPC in this work. CPC with good anti-washout performance was prepared and the effects of the modified starches on the properties of CPC were investigated. The results showed that the CPC with the modified starches were more stable in simulated body fluid than that without modified starch, especially the CPC with the etherified starch (II). X-ray diffraction analysis revealed that the modified starches did not inhibit CPC components from converting to hydroxyapatite. Furthermore, the anti-washout mechanism of the modified starches in CPC was discussed. It is concluded that the addition of the modified starches such as pre-gelatinized starch, etherified starch, and esterified starch to CPC can improve its anti-washout performance and should be of value in clinical surgery where the cement is exposed to blood.

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Baysal, Gülçin, Fatma Neşe Kök, Levent Trabzon, Huseyin Kizil, İkilem Gocek und Burçak Karagüzel Kayaoğlu. „Microfluidic Nonwoven-Based Device as a Potential Biosensor for Sweat Analysis“. Applied Mechanics and Materials 490-491 (Januar 2014): 274–79. http://dx.doi.org/10.4028/www.scientific.net/amm.490-491.274.

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Monitoring body fluids such as sweat composition can provide useful information about the physiological status. Physiological monitoring of body fluids such as sweat with a textile-based system has the advantage of being non-invasive and easily accessible and such monitoring is beneficial to indicate information about body's physiological status. In the present study, it is aimed to design a textile-based system with non-invasive methods which can be used to monitor a sportsman's performance. A novel, disposable and wearable biochemical analytical device was designed and fabricated by patterning micro channels and reservoirs using SU-8 photoresist through photolithography technique on an absorbant bicomponent Evolon® nonwoven substrate. It was obtained that hydrophilic reservoirs were well defined and demarcated by hydrophobic barriers. Therefore, no liquid leakage was observed around the reservoirs which was crucial for achieving a proper enzyme immobilization and the successful detection of the color change after the simulated sweat was deposited on the hydrophilic reservoir areas. Analyte optimization studies revealed that color change became more evident with the increasing analyte concentration until 20 mM and started to decrease with further increase due to analyte inhibition. Also, on textile fabrics, color densities started to decrease after 40 mM analyte concentration.

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Xie, Yao, Jia Liu, Shu Cai, Xiaogang Bao, Qianqian Li und Guohua Xu. „Setting Characteristics and High Compressive Strength of an Anti-washout, Injectable Calcium Phosphate Cement Combined with Thermosensitive Hydrogel“. Materials 13, Nr. 24 (17.12.2020): 5779. http://dx.doi.org/10.3390/ma13245779.

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In this work, a thermosensitive poly(D,L-lactide-co-glycolide)-poly(ethylene glycol)-poly(D,L-lactide-co-glycolide) (PLGA-PEG-PLGA) hydrogel was introduced into calcium phosphate cement (CPC) to enhance the anti-washout property of CPC. The effects of the hydrogel on the setting time, injectability, anti-washout property and compressive strength of CPC were thoroughly investigated. The results showed that the hydrogel significantly increased the injectability and anti-washout property of CPC, meanwhile maintained the setting time with an acceptable range. Moreover, the hydrogel improved the initial compressive strength of CPC. The composite cement with 20% v/v hydrogel in the liquid phase showed fine crystals of hydration product, a more compact microstructure and lower porosity compared with control CPC. The analysis of X-ray diffraction (XRD), infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) indicated that suitable volume ratio of hydrogel (20% v/v) in the setting liquid of CPC could promote the formation of hydroxyapatite in the early hydration period. The degradation behavior of the cement was characterized by immersion tests in simulated body fluid. The hydrogel had no adverse effect on the degradation rate of CPC over the immersion period of 23 days. This study indicated that incorporating PLGA-PEG-PLGA hydrogel could be a promising strategy to reinforce the handing properties and initial compressive strength of calcium phosphate cement.

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Thammarakcharoen, Faungchat, Phee Palanuruksa und Jintamai Suwanprateeb. „In Vitro Resorbability of Three Different Processed Hydroxyapatite“. Key Engineering Materials 659 (August 2015): 3–7. http://dx.doi.org/10.4028/www.scientific.net/kem.659.3.

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Hydroxyapatite has been used as bone substitutes in many applications due to its biocompatibility and osteoconductivity. Generally, it is considered to be biostable and shows limited resorption in the body. In some circumstances, resorption of bone substitutes is more desirable since it could accelerate the bone healing process. It is known that processing route is one of the crucial parameters that could affect the properties of materials. Three different processes were employed in this study to fabricate hydroxyapatite samples including low temperature transformation of three-dimensionally printed calcium sulfate (HA1), high temperature sintering of three-dimensionally printed hydroxyapatite (HA2) and high temperature sintering of mold pressed hydroxyapatite (HA3). HA1 was found to contain high porosity and low crystallinity whereas HA2 had high porosity and high crystallinity. HA3 had low porosity, but high crystallinity. In vitro resorbability of these samples was studied by submerging all the samples in simulated body fluid (SBF) for 1, 7, 14 and 28 days and determining their phase composition, density change, liquid absorption, ions release and microstructure. It was found that HA1 showed the greatest density loss and liquid absorption followed by HA2 and HA3 respectively. Calcium and phosphorus ions in SBF were observed to decrease with submerging times for HA1 and HA2, but remained constant for HA3. SEM studies showed that new calcium phosphate crystals were found to form on the surface of the HA1 and HA2 samples whereas none was found on HA3. These results suggested that HA1 had the greatest resorbability and calcium phosphate crystals forming ability on its surface followed by HA2 and HA3 respectively. Therefore, porosity and crystallinity of the samples resulting from different processing routes are important factors for in vitro resorbability of hydroxyapatite.

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Kinoshita, Keisuke, Hisashi Sato und Yoshimi Watanabe. „Development of Compositional Gradient Simulation for Centrifugal Slurry-Pouring Methods“. Materials Science Forum 631-632 (Oktober 2009): 455–60. http://dx.doi.org/10.4028/www.scientific.net/msf.631-632.455.

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Centrifugal slurry-pouring method has been proposed to fabricate the functionally graded materials (FGMs) with large compositional gradient. This processing method uses the two types of slurries (slurry 1 and slurry 2). The prepared slurry 1 containing one component, particle A, is firstly poured into the mold under the centrifugal force and then the slurry 2 containing two components, particle A and particle B, is poured into the mold. By this process, green body with gradient composition can be obtained and then green body will be sintered by Spark Plasma Sintering method. Finally, it is expected that FGM with gradient from 100% component A at one surface to 100% B at other surface can be fabricated. In this study, the graded distributions of the particle A and particle B within the slurry 2 under the centrifugal force were simulated analyzing the movement of particles in liquid. Moreover, Ti-SiO2 FGMs were experimentally fabricated. The Ti-SiO2 FGM has large compositional gradient on one side of FGM. However, when the size of solid-particle is small, it is difficult to form large compositional gradient in the FGM. This phenomenon obtained by experiment is in agreement with the calculated results. From this result, it is found that the centrifugal slurry-pouring method using different slurries is effective fabrication method for FGMs with large compositional gradient.

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Chen, Guan Sheng, Ren Yuan Zhang, Feng Li, Shi Dong Li und Li Zhang. „Numerical Simulation & Experimental Research of Heat Charging Process of Cylindrical Units with PCM of Al-Si Alloy“. Advanced Materials Research 171-172 (Dezember 2010): 223–28. http://dx.doi.org/10.4028/www.scientific.net/amr.171-172.223.

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Phase change thermal storage used metal as phase change material (PCM) is an important mode of solar thermal energy storage. In this paper, the heat charging processes of solar heating units were simulated under three kinds of heating flux 100,150 and 200kW/m2 at the bottom face respectively, while the thickness of heat receiving layer at the bottom was in 5, 10 and 15mm. Al-Si alloy was selected as PCM used in the cylindrical body of the units which were in the size of φ1000×1000mm. The change of temperature and solid-liquid phase change interface of Al-Si alloy were analyzed to find out the suitable absorber thickness of thermal energy storage units which can run safety under the condition of temperature 700~900K and heat flux 100~200kW/m2, such as the application of solar thermal energy storage unit in high temperature solar thermal power stations. In the last a test system was built up and the experimental result was close to the simulation value of a unit in the size of φ300×1000×10mm.

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Pooput, Kannaporn, Korkiat Sedchaicharn, Anek Phuchamnong und Woranan Petcharoen. „Effect of Heat Treatment on Mechanical and Setting Properties of TTCP-Based Calcium Phosphate Cement“. Key Engineering Materials 798 (April 2019): 59–64. http://dx.doi.org/10.4028/www.scientific.net/kem.798.59.

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The objective of this study was to investigate the effect of heat treatment on setting reaction and mechanical properties of tetracalcium phosphate (TTCP) and dicalcium phosphase (DCP)-based calcium phosphate cements. CPC pastes were prepared at room temperature and heated at different temperatures (from 37 to 60°C) for 10 min. Then, the preheated CPC pastes were rapidly cooled down to room temperature before further heated at 37°C until they set. Three different CPC formulations prepared from different particle sizes of TTCPs were used for the investigation. From the study, it was found that preheating could accelerate setting reaction for all CPCs according to increasing speed of hydroxyapatite (HA) conversion. The higher the preheating temperature, the faster the cements could set. However, at preheating temperature higher than 60°C longer cement setting times were observed. It may be that at high temperature some liquid content in the CPC paste evaporated, resulting in slow setting reaction rate. Compressive strengths of the cements after immersion in simulated body fluid (SBF) for 7 days increased as a result of an increase of HA conversion.

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Pramatarova, Lilyana, Emilia Pecheva, Diana Nesheva, Z. Aneva, Attila Lajos Tóth, Enikõ Horváth und Ferenc Riesz. „Hydroxyapatite Growth on Glass/CdSe/SiO_x Nanostructures“. Solid State Phenomena 106 (September 2005): 123–26. http://dx.doi.org/10.4028/www.scientific.net/ssp.106.123.

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The aim of this study was to find if nanocrystal layers obtained by well-established nanotechnology are able to induce deposition of hydroxyapatite [Ca10(PO4)6(OH)2]. It is known that nanosized objects and porous structures influence biological events and they may be used to create biologically integrated multifunctional devices including biomaterials and sensors. In this work, sequential physical vapour deposition of CdSe and SiO, or SiOx film was used to modify glass substrates. To study the ability of the nanostructured surfaces to induce hydroxyapatite deposition, samples were immersed in a simulated body fluid and simultaneously irradiated with a scanning laser beam for a few minutes. This resulted in a porous sponge-like non homogeneous hydroxyapatite layer, consisting of networks of aggregates of nano dimensions on the modified surfaces. Analysis showed higher Ca and P contents in the stripes of the laser-substrate interaction, which indicated the influence of the laser energy. The method of laser-liquid-solid interaction used has led to a synergistic effect due to the simultaneous use of the nanostructured substrate, aqueous solution and laser energy.

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Hernandez, Olivier, Alain Hédoux, Jacques Lefebvre, Yannick Guinet, Marc Descamps, Robert Papoular und Olivier Masson. „Abinitiostructure determination of triphenyl phosphite by powder synchrotron X-ray diffraction“. Journal of Applied Crystallography 35, Nr. 2 (22.03.2002): 212–19. http://dx.doi.org/10.1107/s0021889802000511.

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The crystal structure of the glass-forming molecular liquid triphenyl phosphite [TPP, P(OC6H5)3, six torsional degrees of freedom] has been solvedab initioat 110 K from powder synchrotron X-ray diffraction data by real-space methods (simulated annealing) followed by rigid-body Rietveld refinements. The symmetry is trigonal, with a rhombohedral lattice, space group R\bar{3}. The associated hexagonal cell, which is a sixfold multiple of the previously published less-symmetric monoclinic cell [Hédouxet al.(1999).Phys. Rev. B,60, 9390–9395], is unusually large [V= 7075.7 (4) Å3,Z= 18] and displays a noteworthy platelet-like shape [a= 37.766 (1) andc= 5.7286 (2) Å]. The TPP molecule does not exhibit the idealC3symmetric propeller shape, its conformation being on the contrary almost mirror-symmetric, with the pseudo-mirror plane passing through the P—O1 bond and two carbon atoms inparaposition with respect to the O1 atom. The hitherto unknown topological features of crystalline TPP, including unusual intermolecular weak C—H...O hydrogen-bonding networks, are presented and discussed in the scope of the `glacial state' problem.

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Kanji, Farhaan, Himanshi Khurana, Caitlin Sherry und Evangeline Ng. „A simulated metagenomic analysis of the gut microbiota of Anorexia Nervosa patients using PICRUSt“. STEM Fellowship Journal 3, Nr. 2 (01.12.2017): 1–3. http://dx.doi.org/10.17975/sfj-2017-012.

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Introduction Mack et al. (2016) studied the fecal bacteria and archaea of 55 European normal-weight participants (NW), 55 European patients with anorexia nervosa (ANT1), and 44 ANT1 patients following a body mass index increase (ANT2). Spreadsheets of identified microbes and their relative abundance per patient were uploaded to the EBI Metagenomics web server by Mack et al. We aimed to further study the functions of the identified microbes using the PICUSt algorithm (Langille, 2013) and see if these functions are consistent with published literature. Methods Spreadsheets were downloaded from EBI Metagenomics (Project# ERP012549) in JSON Biom format and uploaded to a Galaxy cloud server hosting PICRUSt. All data transformations can be viewed at http://huttenhower.sph.harvard.edu/galaxy/u/farhaansgroup/h/anorexi-astem-2017 . Transformed datasets were downloaded, appended with a .biom file extension, converted to the SPF format using STAMP v2.1.3 (Parks, 2014), and merged into a single file using Microsoft Excel for analysis with STAMP. Differences in propionate metabolism between ANT1, ANT2, and NW samples was chosen for further study. Results & Discussion The proportion of propionate metabolism genes was not significantly different between ANT1 and NW samples (p=0.08), but was different between ANT2 and NW samples (p=0.01) using a pair-wise Welsh’s t-test (0.95 CI) with a Storey FDR multiple test correction. In comparison, Mack et al, detected no differences in propionate concentration between AN and NW fecal samples using gas chromatography while Morito et al (2015) found lower concentrations of propionate in Japanese AN versus NW fecal samples using liquid chromatography. Our discrepancy with Mack et al could have arisen since PICRUSt cannot analyze the genes of eukaryotes, PICRUSt is limited by the depth and breadth of the gene annotations in the KEGG database, and our experimental setup cannot provide data on gene expression. Moreover, 18% of V4 16S rRNA DNA sequences could not be matched to any bacteria or archaea by EBI Metagenomics. In conclusion, while in silico experiments can be useful to predict microbial functions in a sample, in this case, our PICRUSt-based hypothesis that fecal samples from Mack et al would have different concentrations of propionate between AN and NW samples was not borne out by Mack et al’s chromatography experiments. Nonetheless, the conflicting findings between us, Mack et al, and Morito et al warrants further research on whether microbes mediate carbohydrate metabolism differently in patients with a history of anorexia nervosa versus controls.

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Medvecky, Lubomir, Maria Giretova, Radoslava Stulajterova, Lenka Luptakova und Tibor Sopcak. „Tetracalcium Phosphate/Monetite/Calcium Sulfate Hemihdrate Biocement Powder Mixtures Prepared by the One-Step Synthesis for Preparation of Nanocrystalline Hydroxyapatite Biocement-Properties and In Vitro Evaluation“. Materials 14, Nr. 9 (22.04.2021): 2137. http://dx.doi.org/10.3390/ma14092137.

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A modified one-step process was used to prepare tetracalcium phosphate/monetite/calcium sulfate hemihydrate powder cement mixtures (CAS). The procedure allowed the formation of monetite and calcium sulfate hemihydrate (CSH) in the form of nanoparticles. It was hypothesized that the presence of nanoCSH in small amounts enhances the in vitro bioactivity of CAS cement in relation to osteogenic gene markers in mesenchymal stem cells (MSCs). The CAS powder mixtures with 15 and 5 wt.% CSH were prepared by milling powder tetracalcium phosphate in an ethanolic solution of both orthophosphoric and sulfuric acids. The CAS cements had short setting times (around 5 min). The fast setting of the cement samples after the addition of the liquid component (water solution of NaH2PO4) was due to the partial formation of calcium sulfate dihydrate and hydroxyapatite before soaking in SBF with a small change in the original phase composition in cement powder samples after milling. Nanocrystalline hydroxyapatite biocement was produced by soaking of cement samples after setting in simulated body fluid (SBF). The fast release of calcium ions from CAS5 cement, as well as a small rise in the pH of SBF during soaking, were demonstrated. After soaking in SBF for 7 days, the final product of the cement transformation was nanocrystalline hydroxyapatite. The compressive strength of the cement samples (up to 30 MPa) after soaking in simulated body fluid (SBF) was comparable to that of bone. Real time polymerase chain reaction (RT-PCR) analysis revealed statistically significant higher gene expressions of alkaline phosphatase (ALP), osteonectin (ON) and osteopontin (OP) in cells cultured for 14 days in CAS5 extract compared to CSH-free cement. The addition of a small amount of nanoCSH (5 wt.%) to the tetracalcium phosphate (TTCP)/monetite cement mixture significantly promoted the over expression of osteogenic markers in MSCs. The prepared CAS powder mixture with its enhanced bioactivity can be used for bone defect treatment and has good potential for bone healing.

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