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1
Koch, L., N. Steinbock, and G. Krueger. "THERMAL ASYMMETRY ANALYSIS OF MOTORIZED SPINDLES." MM Science Journal 2021, no. 3 (June 30, 2021): 4612–19. http://dx.doi.org/10.17973/mmsj.2021_7_2021067.
Повний текст джерелаАнотація:
This paper presents a method to quantify and reduce thermal asymmetry of motorized spindles. Thermal asymmetry leads to angular and radial deflections at the tool center point. In contrast to simple thermal expansion issues, these effects are harder to compensate. Therefore, the causes of the asymmetries should preferably be evident in the construction phase. This paper introduces a newly developed mathematical formulation to quantify thermal asymmetry. Thermal asymmetry is observed along the longitudinal axis of a motorized spindle. The formulation quantifies thermal asymmetries as a difference of a geometrical centroid and a newly introduced thermal centroid. For this analysis, several motor spindles with different fluid cooling circulation systems were observed. In order to show the legitimacy of the formulation, the spindle’s calculated thermal asymmetries are compared with their respective radial tool center point displacements. The results show that the asymmetries correlate with the displacements. Furthermore, the quantification of the thermal asymmetry actually allows to locate its causes. In motor spindles the asymmetry is mostly caused by the complex fluid circulation system. The spindle with the worst cooling circulation showed a radial displacement of 26,32 µm. Through thermal asymmetry optimization of the circulation’s heat transfer, the displacement could be reduced to 0,66 µm. The developed method is not limited to motorized spindles. It will be investigated further to develop a generally valid formulation.
2
Suzuki, N., C. L. Prosser, and W. DeVos. "Waxing and waning of slow waves in intestinal musculature." American Journal of Physiology-Gastrointestinal and Liver Physiology 250, no. 1 (January 1, 1986): G28—G34. http://dx.doi.org/10.1152/ajpgi.1986.250.1.g28.
Повний текст джерелаАнотація:
Electrical slow waves from cat or rabbit small intestine show more variability when recorded in vivo than in vitro. One pattern of variation is waxing and waning of amplitude, or "spindling," during which two rhythms of slightly different frequency come in and out of phase. Fourier power analyses of slow waves during spindles show two frequency peaks of slow waves differing by 0.4-5.0 waves/min and corresponding to measured spindle durations of 12-150 s. Spindles can be induced in vitro in rabbit intestine by K depolarization of approximately 15 mV. Histograms of intracellular recordings of slow nonspindling waves show variation of 0.5-1.0 s on either side of a mean slow wave duration. Spindles are abolished by treatments that reduce electrical coupling between cells, e.g., hypertonic sucrose or lowered pH, but changes in calcium do not alter spindles. Simultaneous recordings by two electrodes in the longitudinal axis show synchrony of spindles at 2- to 3-mm but not at 5-mm separation and synchrony circumferentially to the opposite side of a segment. Contractions, both in vivo and in vitro, correspond with electrical spindles in amplitude. Spindle durations were significantly shorter in vivo than in vitro, indicating a significantly greater difference in vivo in the competing frequencies at the point of recording (P less than 0.01). Three conditions favoring waxing and waning are slight depolarization, variation in slow wave frequency at a point, and electrotonic coupling between muscle fibers. Spindles provide for rhythms of contractions of a 1- to 2-min period.
3
Guo, Shijie, Shufeng Tang, Gedong Jiang, and Xuesong Mei. "Highly efficient and accurate calibration method for the position-dependent geometric errors of the rotary axes of a five-axis machine tool." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 235, no. 1-2 (September 20, 2020): 23–33. http://dx.doi.org/10.1177/0954405420951096.
Повний текст джерелаАнотація:
This paper proposes a calibration method for continuous measurements with a double ball bar (DBB) used to identify the position-dependent geometric errors (PDGEs) of the rotary axes of five-axis machine tools. The different DBB installation modes for the rotary axes of the spindle and workbench are established, and the same initial DBB installation position is used for multiple tests. This approach minimizes the number of required DBB installations, which increases the measurement efficiency of the PDGEs of the rotary axes and reduces installation errors. PDGEs identification based on the adaptive least absolute shrinkage and selection operator (LASSO) method is proposed. By assigning coefficients to the PDGEs polynomial, the ill-conditioned problem of the identification process can be effectively avoided, thereby improving the identification accuracy. The measurement and identification methods proposed in this paper are verified by experiments on a five-axis machine tool. After compensation, the PDGEs are obviously reduced and the accuracy indexes of the circular trajectory tests performed under multiaxis synchronous control are obviously improved.
4
Zhang, Lei, Qing Jian Liu, Tai Yong Wang, Hong Bin Li, and Wei Tian. "Structural Design and Improvement of Spindle in Five-Axis Wood Engraving Machine." Key Engineering Materials 693 (May 2016): 200–204. http://dx.doi.org/10.4028/www.scientific.net/kem.693.200.
Повний текст джерелаАнотація:
In the wood engraving industry, the double swing motor spindle or the double rotation motor spindle is often used as the spindle of five-axis wood engraving machine to achieve three-dimensional sculpture. However, the rough and motor spindle may interfere with each other during machining. Hence, many small regions of rough cannot be machined. To solve this problem, an anthropomorphic double-swing-head mechanism is designed. Instead of motor spindle, the designed mechanism is used as spindle of five-axis wood engraving machine. The level of automation and machining scope of the machine are improved. The workload of subsequent artificial modification is reduced. Then, the machining efficiency and quality of wood products are enhanced, and their production costs are reduced.
5
N. Srinivasan and M. Gunasekaran. "CURATIVE AND PROPHYLACTIC CONTROL OF FUNGAL LEAF ROT COMPLEX IN ROOT (WILT) AFFECTED COCONUT PALMS IN INDIA." CORD 19, no. 01 (June 1, 2003): 34. http://dx.doi.org/10.37833/cord.v19i01.365.
Повний текст джерелаАнотація:
Root wilt disease (RWD) is a debilitating malady of coconut in India that is caused by phytoplasma. In RWD affected palms, leaf rot disease (LRD) is commonly superimposed. The LRD is due to fungi and this leaf rot phase forms an integral part of RWD complex. Control of LRD is important as it severely disfigures the palm and brings about rapid deterioration in its health and productivity. Control trial involving Phytosanitation of young leaves, pouring of broad spectrum - systemic fungicide, Contaf 5 E (Hexaconazole 5% EC) into the axil of spindle leaf besides a number of other measures was conducted to study their ameliorating effect on LRD. Prophylactic control trial, especially with the broad-spectrum fungicides was also conducted. Pouring of Contaf into the axil of spindles along with phytosanitory measures on the spindle and other young leaves significantly reduced the incidence of LRD in newly emerging spindles effecting cure. Application of the fungicide on RWD palms prior to the onset of LRD, offered prophylactic protection to emerging leaves against LRD. Relevance of practising integrated control measures, cure of LRD at an early stage itself, the need for strict adoption of crop management technology etc. for effective disease control are highlighted here.
6
Krstić, Vladislav, Dragan Milčić, and Miodrag Milčić. "A THERMAL ANALYSIS OF THE THREADED SPINDLE BEARING ASSEMBLY IN NUMERICALLY CONTROLLED MACHINE TOOLS." Facta Universitatis, Series: Mechanical Engineering 16, no. 2 (August 1, 2018): 261. http://dx.doi.org/10.22190/fume170512022k.
Повний текст джерелаАнотація:
A threaded gear in machine tools is a mechanical actuator that converts rotary motion into linear one of the machine axis using a recirculating ball-nut. It provides positioning accuracy, uniform motion, silent operation, reduced wear and an increased service life. The bearing assembly of the threaded spindles should provide load transfer (cutting forces and friction forces) while maintaining high guiding accuracy. Due to a high number of the threaded spindle revolutions and the presence of tension in the bearing and a high axial force originating from the cutting and friction forces, the increased heat load due to friction in the bearings is normally expected. For this reason, this paper presents a thermal analysis of the bearing assembly of the threaded spindle which is realized via an axial ball bearing with angular contact of the ZKLN type, produced by the German manufacturer Schaeffler (INA); in other words, a numerical thermal analysis has been performed.
7
Gupta, Mohan L., Claudia J. Bode, Douglas A. Thrower, Chad G. Pearson, Kathy A. Suprenant, Kerry S. Bloom та Richard H. Himes. "β-Tubulin C354 Mutations that Severely Decrease Microtubule Dynamics Do Not Prevent Nuclear Migration in Yeast". Molecular Biology of the Cell 13, № 8 (серпень 2002): 2919–32. http://dx.doi.org/10.1091/mbc.e02-01-0003.
Повний текст джерелаАнотація:
Microtubule dynamics are influenced by interactions of microtubules with cellular factors and by changes in the primary sequence of the tubulin molecule. Mutations of yeast β-tubulin C354, which is located near the binding site of some antimitotic compounds, reduce microtubule dynamicity greater than 90% in vivo and in vitro. The resulting intrinsically stable microtubules allowed us to determine which, if any, cellular processes are dependent on dynamic microtubules. The average number of cytoplasmic microtubules decreased from 3 in wild-type to 1 in mutant cells. The single microtubule effectively located the bud site before bud emergence. Although spindles were positioned near the bud neck at the onset of anaphase, the mutant cells were deficient in preanaphase spindle alignment along the mother-bud axis. Spindle microtubule dynamics and spindle elongation rates were also severely depressed in the mutants. The pattern and extent of cytoplasmic microtubule dynamics modulation through the cell cycle may reveal the minimum dynamic properties required to support growth. The ability to alter intrinsic microtubule dynamics and determine the in vivo phenotype of cells expressing the mutant tubulin provides a critical advance in assessing the dynamic requirements of an essential gene function.
8
Yang, Z., Z. Q. Qu, R. B. Mu, K. Y. Ji, and M. Zhao. "Study on the temperature field of stone processed by diamond tools." IOP Conference Series: Materials Science and Engineering 1242, no. 1 (April 1, 2022): 012041. http://dx.doi.org/10.1088/1757-899x/1242/1/012041.
Повний текст джерелаАнотація:
Abstract The experiments were designed by testing methods and orthogonal single factor experimental design. XK5032C CNC milling machine, the equipment to achieve X-axis, Y-axis and 3-axis Z direction of the automatic feed, spindle cooling method using water-cooled. In different processing parameters (spindle speed, depth of cut and feed rate), measurement of the surface temperature of diamond tools. In the testing experiment result analysis, we conclude, the depth of cutting is the biggest influence on the surface temperature. From the orthogonal experiment data analysis, we found that, the temperature was reduced with spindle rotation but opposite with two other factors. By linear regression analysis. We get the best cutting results by choosing a large spindle rotation and a small feed rate.
9
Hu, Zheng Bang, Xia Lun Yun, Ge Dong Jiang, Chang Jianig Chen, and Xue Song Mei. "Non-Stationary Signal Purification and Rotor Axis Orbit Feature Extraction under Machine Tool Spindle Cutting Process." Applied Mechanics and Materials 868 (July 2017): 305–10. http://dx.doi.org/10.4028/www.scientific.net/amm.868.305.
Повний текст джерелаАнотація:
Rotor axis orbit measurement of the spindle under cutting process is the important basis of cutting quality judgment and spindle fault diagnosis. In the cutting process, the non-stationary characteristics of vibration measurement signal of spindle rotor has been particularly outstanding, under such circumstances it is difficult to draw spindle rotor axis orbit accurately. To solve this problem, a new method using EEMD (Ensemble Empirical Mode Decomposition) and harmonic wavelet is put forward to realize non-stationary signal purification and rotor axis orbit feature extraction under machine tool spindle cutting process. In order to filter out the high frequency noise of the measurement, the EEMD method has been used, in addition that the characteristics of the original signal is preserved well. However the signal after EEMD filter still contains a variety of frequency components, in order to solve it, the harmonic wavelet method is used to decompose the signal into several signals according to the different frequency components, through the signal reconstruction achieve rotor axis orbit feature extraction. Using this method, the machined workpiece has been cut under the speed of 12000r/min, the vibration of spindle has been measured and processed. The experiment results show that the new method can effectively reduce the high frequency interference noise signal, and also apparently the rotor axis orbit obtained is more clearly than the original rotor axis orbit.
10
Saxton, W. M., and J. R. McIntosh. "Interzone microtubule behavior in late anaphase and telophase spindles." Journal of Cell Biology 105, no. 2 (August 1, 1987): 875–86. http://dx.doi.org/10.1083/jcb.105.2.875.
Повний текст джерелаАнотація:
We have studied microtubule behavior in late anaphase and telophase spindles of PtK1 cells, using fluoresceinated tubulin (DTAF-tubulin), microinjection, and laser microbeam photobleaching. We present the results of two novel tests which add to the evidence that DTAF-tubulin closely mimics the behavior of native tubulin in vivo. (a) Microinjected DTAF-tubulin was as effective as injected native tubulin in promoting division of taxol-dependent mitotic mutant cells that had been deprived of taxol. (b) Microinjected colchicine-DTAF-tubulin complex was similar to injected colchicine-native tubulin complex in causing depolymerization of spindles. Immediately after microinjection of DTAF-tubulin into wild-type cells during late anaphase or telophase, fluorescence incorporation by microtubules was seen in chromosomal half-spindles and just behind the chromosomes, but there was no fluorescence incorporation near the middle of the interzone. Over the next few minutes, tubulin fluorescence accumulated at the center of the interzone (the equator), becoming progressively more intense. In other experiments, cells were microinjected with DTAF-tubulin at prophase and allowed to equilibrate for 30 min. Cells that had progressed to late anaphase were then photobleached to reduce the fluorescence in the central portion of the interzone. Over a period of several minutes, the only substantial redistribution of fluorescence was the appearance of a bright area at the equator of the interzone. Both the site of fluorescence incorporation and the photobleaching data suggest that tubulin adds to the elongating spindle interzone near the equator where the plus ends of the interdigitated microtubules are located. In further experiments, several dark lines were photobleached perpendicular to the pole-to-pole axis of fluorescent anaphase-telophase spindles. Time-dependent changes in the spacings between the lines indicated that the two halves of the interzone lying on opposite sides of the spindle equator moved away from one another. This shows that the interdigitated microtubules, which make up most of the interzone, can undergo antiparallel sliding. Our data support a model for anaphase B in which plus end elongation of interdigitated microtubules and antiparallel sliding contribute to chromosome separation.
11
Пономарев, Б., Boris Ponomarev, Хьен Нгуен, and Hien Nguyen. "DYNAMICS OF FIVE-AXIS END MILLING PROCESS." Bulletin of Belgorod State Technological University named after. V. G. Shukhov 4, no. 7 (July 21, 2019): 108–20. http://dx.doi.org/10.34031/article_5d35d0b677dc74.96046396.
Повний текст джерелаАнотація:
The article presents the experimental results of the influences of machining conditions and tool orientation on cutting forces during the end milling of free-form surfaces. A series of experiments are carried out on the machining of steel 3 blanks on a five-axis milling machine model HSC 75 linear using 2-flute and 4-flute ball end mills from MITSUBISHI with diameters from 5 mm to 10 mm. The dependency diagrams and graphs of cutting forces and their projections on cutting time are given at different spindle speeds, feeds per tooth, depths of cut, tilt angles and lead angle when using different ball end mills. Based on the results of the analysis of experimental data, the theoretical conclusion about the increase in cutting forces with increasing feed per tooth, cutting depth and spindle speed in relation to the ball end milling process is confirmed. The critical tool positions with respect to the surface, at which cutting forces have maximum values, are revealed. The obtained results allow developing recommendations for the choice of the tool position during end milling of free-form surfaces to reduce loads on the tool
12
Doronkin, Sergey, Inna Djagaeva, and Steven K. Beckendorf. "CSN5/Jab1 mutations affect axis formation in theDrosophila oocyte by activating a meiotic checkpoint." Development 129, no. 21 (November 1, 2002): 5053–64. http://dx.doi.org/10.1242/dev.129.21.5053.
Повний текст джерелаАнотація:
The COP9 signalosome (CSN) is linked to signaling pathways and ubiquitin-dependent protein degradation in yeast, plant and mammalian cells,but its roles in Drosophila development are just beginning to be understood. We show that during oogenesis CSN5/JAB1, one subunit of the CSN,is required for meiotic progression and for establishment of both the AP and DV axes of the Drosophila oocyte. The EGFR ligand Gurken is essential for both axes, and our results show that CSN5 mutations block the accumulation of Gurken protein in the oocyte. CSN5 mutations also cause the modification of Vasa, which is known to be required for Gurken translation. This CSN5 phenotype — defective axis formation, reduced Gurken accumulation and modification of Vasa — is very similar to the phenotype of the spindle-class genes that are required for the repair of meiotic recombination-induced, DNA double-strand breaks. When these breaks are not repaired, a DNA damage checkpoint mediated by mei-41 is activated. Accordingly, the CSN5 phenotype is suppressed by mutations inmei-41 or by mutations in mei-W68, which is required for double strand break formation. These results suggest that, like thespindle-class genes, CSN5 regulates axis formation by checkpoint-dependent, translational control of Gurken. They also reveal a link between DNA repair, axis formation and the COP9 signalosome, a protein complex that acts in multiple signaling pathways by regulating protein stability.
13
Showa, Yuta, and Hayato Yoshioka. "Reduction of the Influence of Non-Repeatable Run-Out in X-Y Plane of Machining Surface." International Journal of Automation Technology 16, no. 2 (March 5, 2022): 149–56. http://dx.doi.org/10.20965/ijat.2022.p0149.
Повний текст джерелаАнотація:
In recent years, the quality of the machined surfaces of molds for optical or medical instruments has needed improvement, and the fabrication of mirrored surfaces by means of cutting only has been gaining in importance. In order to obtain smooth surfaces, it is necessary to reduce various vibrations in the machine tool during the machining process. Many factors cause vibration in a machine tool, including feed mechanisms, pumps, and chatter. A high-speed spindle for precision machining is one source of vibration, but it is a challenge to avoid the non-repeatable run-out (NRRO) of a spindle. This study has developed an excitation system that can reduce the influence of non-repeatable run-out on machining surfaces. This paper presents a newly-developed excitation system with an excitation unit for each the X and Y direction. The excitation units consist of a voice coil motor and leaf springs, fixed on a spindle head. The tool run-out and vibration of the spindle head are measured by a displacement sensor and an acceleration sensor fixed on the spindle head, and their NRRO components are obtained through extraction using band-pass filters. By using these NRRO components as feedback signals, the excitation unit generates the force to cancel the NRRO of the tool. In order to determine the performance of the developed system, experimental evaluation was performed on a vertical 3-axis machining center. Since the spindle used for evaluation had three bearings, the measured NRRO of the tool had three peaks in the frequency domain. First, we conducted evaluation experiments under non-machining conditions, and all NRRO peaks were reduced by applying the developed system. Furthermore, there was no interference of the excitation units in the X and Y directions. Next, we evaluated the influence of the NRRO of the tool on the machining surface under finish machining conditions. The reduction in NRRO components in the measured surface profiles was observed through feedback. It was concluded that the developed system can reduce the influence of NRRO on machining surfaces.
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Ducheyne, Kaatje D., Marilena Rizzo, Peter F. Daels, Tom A. E. Stout, and Marta de Ruijter-Villani. "Vitrifying immature equine oocytes impairs their ability to correctly align the chromosomes on the MII spindle." Reproduction, Fertility and Development 31, no. 8 (2019): 1330. http://dx.doi.org/10.1071/rd18276.
Повний текст джерелаАнотація:
Vitrified–warmed immature equine oocytes are able to complete the first meiotic division, but their subsequent developmental competence is compromised. Therefore, the present study investigated the effects of vitrifying immature horse oocytes on the chromosome and spindle configuration after IVM. Cumulus–oocytes complexes (COCs) were collected and divided into two groups based on mare age (young ≤14 years; old ≥16 years). COCs were then either directly matured invitro or vitrified and warmed before IVM. Spindle morphology and chromosome alignment within MII stage oocytes were assessed using immunofluorescent staining, confocal microscopy and three-dimensional image analysis. Vitrification reduced the ability of oocytes to reach MII and resulted in ultrastructural changes to the meiotic spindle, including shortening of its long axis, and an increased incidence of chromosomes failing to align properly at the metaphase plate. We hypothesise that aberrant chromosome alignment is an important contributor to the reduced developmental competence of vitrified equine oocytes. Contrary to expectation, oocytes from young mares were more severely affected than oocytes from older mares; we propose that the reduced effect of vitrification on oocytes from older mares is related to pre-existing compromise of spindle assembly checkpoint control mechanisms in these mares.
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Mohd Hadzley, Abu Bakar, Muhammad Hafiz Samsudin, Mohd Najib Zamri, Raja Izamshah Raja Abdullah, Mohd Shahir Kasim, and Abu Abdullah. "Development of Three-Axis Mini Milling Machine for Small Scale Production." Applied Mechanics and Materials 761 (May 2015): 273–76. http://dx.doi.org/10.4028/www.scientific.net/amm.761.273.
Повний текст джерелаАнотація:
This paper presents the processes to develop a cost-effective small scale 3-axis CNC milling machine. The designed machine tool consisted of stepper motors, bearing, linear guide, ball screw mounting systems, inverter and electronic controller, in which all of these are assembled together in a form of 3-axis operating system. The machine has a built up with the size of 1000 mm (length) × 1000 mm (width) × 650 mm (long) accompanied with a worktable with a dimension of 300 mm (length) × 300 mm (width) × 20 mm (long), and 24,000 rpm maximum spindle speed. To control the movement of the machine, open source software was utilized with the aid of G-Codes to assign the movement of the CNC axes. From the machining test, the machine was found to be capable to machine a metal work piece with high cutting speed and reasonable accuracy. The machine developed in this study offers efficiency and flexibility in the manufacturing production which enables to reduce capital cost due to the small-scale facility.
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Lee, Wei Chen, and Shan Chen Chung. "Design of a Hybrid 5-Axis Machine Tool with Fused-Deposition-Modeling Capability." Applied Mechanics and Materials 446-447 (November 2013): 566–70. http://dx.doi.org/10.4028/www.scientific.net/amm.446-447.566.
Повний текст джерелаАнотація:
The objective of this paper is to present the design and fabrication of a hybrid 5-axis machining and rapid prototyping machine tool. The rapid prototyping used for this machine was fused deposition method. The extruder of the fused deposition method and the cutting spindle were installed on each end of the rotary axis respectively to reduce the complexity of this machine. Preliminary experimental results demonstrated that the machine can increase the accuracy of the product made by low-cost fused deposition method.
17
Denkena, B., B. Bergmann, K. Kono, R. Ishiguro, and H. Klemme. "CHARACTERIZATION OF HEAT CONDUCTIVITY OF ECCENTRICALLY ROTATING HEAT PIPES USED FOR COOLING OF MOTOR SPINDLES." MM Science Journal 2021, no. 3 (June 30, 2021): 4698–705. http://dx.doi.org/10.17973/mmsj.2021_7_2021078.
Повний текст джерелаАнотація:
Heat losses within motor spindles lead to undesired effects such as machining inaccuracies and de-creasing lifetime of the motor and bearings. To reduce thermal loads, complex shaft cooling concepts with costly sealing techniques exist. For this reason, a novel, less costly cooling concept has been de-veloped based on heat pipes with high thermal conductivity and fin-shaped heat exchangers. The de-sign and integration of these heat exchanger elements into a motor spindle is carried out using the fi-nite element method. The aim is to optimize the efficiency of the heat pipes and heat exchangers for optimal shaft cooling performance. For a simulation-based development of a prototype spindle, un-known thermal characteristics of the heat transfer elements must be determined. In this paper, the de-termination of the thermal conductivity of the heat pipes is described. The determination of conductivi-ty is done experimentally. First, the developed test rig and the applied procedure for the determination of the conductivity are shown. Subsequently, the experimental results are presented and discussed. Two types of heat pipes were analyzed: Copper heat pipes with sintered wick structure and nickel-plated copper heat pipes with axial grooves. The influences of rotational speed, heat flow rates and the angle between the heat pipe and main axis of rotation were investigated. The results indicate a distinct dependency of the conductivity on the varied parameters. However, changes of parameter values have very different quantitative and qualitative effects on the determined conductivities de-pending on the type of heat pipe.
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P. Sundar Singh Sivam, S., K. Saravanan, N. Pradeep, S. Rajendra Kumar, and Sathiyamoorthy Karuppiah. "Comparison of Manufacturing Data Analysis For 5 & 3-Axis Vertical Machining Center for the Time and Tool Benefits of Industries." International Journal of Engineering & Technology 7, no. 4.5 (September 22, 2018): 196. http://dx.doi.org/10.14419/ijet.v7i4.5.20044.
Повний текст джерелаАнотація:
The dawn of globalization of business and competitiveness in manufacturing has forced firms to enhance their manufacturing facilities to reply to plug necessities. One of the crucial factors for this is often machine evaluation that involves a crucial decision using general and obscure information. The Primarily mass production aims high productivity so as to reduce cost and interchangeability to facilitate simple assembly which necessitates the production devices to increase the speed of manufacture. Across the business, the assembly challenges pivot around cutting lead times, increasing throughout and obtaining products to market as quickly as possible alongside some less challenging problems like shorter runs, higher product combine, tighter tolerances, a lot of complicated geometries in harder materials, and complete machining during a single handling. Advancements in technology have resulted in a creation of a lot of responsive tools referred to as MTM systems that are computer numerical Control (CNC) systems capable of acting a variety of operations with multiple tools and spindles in a single setup. The following project aims at reduction of manufacturing cost by modifying the process layout and operational parameters by novel approach for an identical element for 3 and 5- Axis Vertical Machining center. Nowadays, machining layout and operational sequence plays a significant role in automotive business to produce products at competitive price in market which consists of Machines, Tools, fixtures, computer interface, trained professionals and form of products. MAKINO PS60 is a Multi axis CNC machine (BRIDGE PORT), that helps to perform the machining operations on the roles at 5 totally different axes to create the required profiles whose implementation can pave means for a few terribly important benefits like, seven machines are replaced by Single machine, Man power are reduced from 9 to 3 per day, Tools usage reduced from 40 to 30 per day & production cost can reduce up to 60%.
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Li, Yong, and Shaoping Zhou. "Sensorless balance method for the spindle system of computer numerical control gear grinding machine." Measurement and Control 51, no. 9-10 (October 8, 2018): 460–69. http://dx.doi.org/10.1177/0020294018802715.
Повний текст джерелаАнотація:
Background: Spindle imbalance vibration of the computer numerical control grinding machine may result in dramatic effects on tool wear, surface finish, and form-holding of the products, which makes the balancing procedure very essential during their manufacturing process. Although the spindle residual vibration in a single direction can be suppressed effectively by the commonly used commercial balance systems, some real-world application results show that most of these balance systems cannot reduce the spindle residual vibration in horizontal, vertical, and axial direction simultaneously. Methods: To overcome this issue, the limitation of commonly used influence coefficient method–based spindle balance method is discussed first. After that, a novel balance method is experimentally proposed for the spindle vibration control using the position fluctuation information between the carriage and guideway of the servo-axis. In this method, the position fluctuation information between the carriage and guideway and the key phase information are practically measured using the built-in linear scale and spindle servomotor encoder, respectively, in which the position fluctuation information between the carriage and guideway can be considered as an integrated representation of the spindle imbalance vibration. Combined with the influence coefficient method, the imbalance vibration presenting in the horizontal, vertical, and axial direction of the spindle can be suppressed simultaneously and effectively. Results and Conclusions: A field balancing experiment is carried out on a high-precision computer numerical control gear grinding machine. Experiment results demonstrate that, compared with the commonly used commercial balancing system, the proposed method can not only reduce the residual vibration amplitude at the objective balancing speed effectively but also reduce the residual vibration amplitude more than 50% simultaneously in each direction during the whole run-down process.
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Wang, Zhan, Dongzheng Li, Zinan Wang, Aoxiang Liu, and Ruiyao Tao. "Research on Dynamic Balance of Spindle Rotor System Based on Particle Swarm Optimization." Advances in Materials Science and Engineering 2021 (December 20, 2021): 1–12. http://dx.doi.org/10.1155/2021/9728248.
Повний текст джерелаАнотація:
The dynamic balance is a significant issue for the nonlinear dynamic characteristics of the spindle rotor system. However, there is a problem that the dynamic balance is lacking detailed study on optimization method. In the paper, a modal dynamic balance optimization model of spindle rotor system is proposed, which can intend to improve the accuracy of spindle rotor system modal dynamic balance. Because the multiorder unbalance components are the main spindle rotor system mode shapes, the particle swarm optimization (PSO) method is adopted. The sum of squares of residual vibration after balancing is taken as the optimization objective, and the correction is presented as the optimization variable in the optimization model. The optimal correction weight of every unbalance component is calculated through a modal matrix equation of PSO. The vibration amplitude that is greatly reduced after optimization balance is presented under different conditions. The balancing effect shows a better dynamic characteristic than that of traditional methods. And the fluctuation range of the axis track of the rotor system also shows reductive phenomenon. The proposed optimization spindle rotor system model is well verified through experiments. It can contribute a theoretical optimization foundation for available dynamic balance in spindle rotor system.
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Yang, Zhenye, Jing Guo, Qi Chen, Chong Ding, Juan Du, and Xueliang Zhu. "Silencing Mitosin Induces Misaligned Chromosomes, Premature Chromosome Decondensation before Anaphase Onset, and Mitotic Cell Death." Molecular and Cellular Biology 25, no. 10 (May 15, 2005): 4062–74. http://dx.doi.org/10.1128/mcb.25.10.4062-4074.2005.
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ABSTRACT Mitosin (also named CENP-F) is a large human nuclear protein transiently associated with the outer kinetochore plate in M phase. Using RNA interference and fluorescence microscopy, we showed that mitosin depletion attenuated chromosome congression and led to metaphase arrest with misaligned polar chromosomes whose kinetochores showed few cold-stable microtubules. Kinetochores of fully aligned chromosomes often failed to show orientation in the direction of the spindle long axis. Moreover, tension across their sister kinetochores was decreased by 53% on average. These phenotypes collectively imply defects in motor functions in mitosin-depleted cells and are similar to those of CENP-E depletion. Consistently, the intensities of CENP-E and cytoplasmic dynein and dynactin, which are motors controlling microtubule attachment and chromosome movement, were reduced at the kinetochore in a microtubule-dependent manner. In addition, after being arrested in pseudometaphase for approximately 2 h, mitosin-depleted cells died before anaphase initiation through apoptosis. The dying cells exhibited progressive chromosome arm decondensation, while the centromeres were still associated with spindles. Mitosin is therefore essential for full chromosome alignment, possibly by promoting proper kinetochore attachments through modulating CENP-E and dynein functions. Its depletion also prematurely triggers chromosome decondensation, a process that normally occurs from telophase for the nucleus reassembly, thus resulting in apoptosis.
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Li, Jian, Yong Chang Luo, and Xiao Fan Nie. "Error Analysis of Ladder Shaft Turning and the Research of NC Compensation." Advanced Materials Research 189-193 (February 2011): 2312–16. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.2312.
Повний текст джерелаАнотація:
To reduce the ladder axis machining error, in this paper, the finish turning of a machine tool spindle and the rough turning process is analyzed, were calculated the change of step-axis contour deformation in the process of the finish turning and rough turning with limited difference method and the finite element method (the elastic constraint and inelastic constraint in both ends ). Comparison of the deformation of the three profile, to find more realistic results, and simulate the spline of shaft ladder deformation, using Compensation method to process NC programming. To improve the processing quality of stepped shaft.
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Lezzer, Paolo, Stuart Tustin, Luca Corelli-Grappadelli, Sara Serra, Brendon Anthony, Alberto Dorigoni, and Stefano Musacchi. "Influences of Propagation Method, Rootstock, Number of Axes, and Cultivation Site on ‘Fuji’ Scions Grown as Single or Multi-Leader Trees in the Nursery." Agronomy 12, no. 1 (January 17, 2022): 224. http://dx.doi.org/10.3390/agronomy12010224.
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The adoption of high-density plantings (HDP) in apple orchards started with the introduction of dwarfing rootstocks from East Malling’s (UK) breeding program. A range of spindle-derived training systems have been developed to improve light interception/distribution with a variation in leader numbers. Many of these training systems cannot guarantee early, consistent, and uniform illumination of the entire canopy. For this reason, planar 2-D canopies have been developed with varying numbers of primary axes with numerous second-order shoots. In this trial, carried out at the nursery level, three sites were selected: one in New Zealand (Hawke’s Bay Research Centre) and two in Italy (Bologna and Trento). Trees were produced with a single-, bi-, and tri-axis system utilizing three rootstocks (‘M27’, ‘M9’, ‘MM106’), characterized by an increasing level of vigor. The cultivation site played an important role in modulating early tree performance. Multi-leader trees reduced average shoot length in the Italian sites in the first year after grafting. The number of shoots and total growth developed on multi-leader trees was higher than single-axis trees. This may benefit growers that seek to use canopy architecture manipulation to fill space and control vigor when establishing HDP orchards.
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Merk, Daniel J., Pengcheng Zhou, Samuel M. Cohen, Maria F. Pazyra-Murphy, Grace H. Hwang, Kristina J. Rehm, Jose Alfaro, et al. "The Eya1 Phosphatase Mediates Shh-Driven Symmetric Cell Division of Cerebellar Granule Cell Precursors." Developmental Neuroscience 42, no. 5-6 (2020): 170–86. http://dx.doi.org/10.1159/000512976.
Повний текст джерелаАнотація:
During neural development, stem and precursor cells can divide either symmetrically or asymmetrically. The transition between symmetric and asymmetric cell divisions is a major determinant of precursor cell expansion and neural differentiation, but the underlying mechanisms that regulate this transition are not well understood. Here, we identify the Sonic hedgehog (Shh) pathway as a critical determinant regulating the mode of division of cerebellar granule cell precursors (GCPs). Using partial gain and loss of function mutations within the Shh pathway, we show that pathway activation determines spindle orientation of GCPs, and that mitotic spindle orientation correlates with the mode of division. Mechanistically, we show that the phosphatase Eya1 is essential for implementing Shh-dependent GCP spindle orientation. We identify atypical protein kinase C (aPKC) as a direct target of Eya1 activity and show that Eya1 dephosphorylates a critical threonine (T410) in the activation loop. Thus, Eya1 inactivates aPKC, resulting in reduced phosphorylation of Numb and other components that regulate the mode of division. This Eya1-dependent cascade is critical in linking spindle orientation, cell cycle exit and terminal differentiation. Together these findings demonstrate that a Shh-Eya1 regulatory axis selectively promotes symmetric cell divisions during cerebellar development by coordinating spindle orientation and cell fate determinants.
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Yamashita, Tatsuya, Toshiki Hirogaki, Eiichi Aoyama, Ryousuke Shibata, and Keiji Ogawa. "Investigation of Step Micro-Drilling Motion Based on Modeling of High Speed Spindle Driving Axis on Machine Tools Equipped with Vibration-Proof Mechanism." Advanced Materials Research 1017 (September 2014): 642–47. http://dx.doi.org/10.4028/www.scientific.net/amr.1017.642.
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Recently, there has been an increasing demand for miniaturization and multi-functionalization of electronic equipments due to the developments in information technology (IT). Thus, the miniaturization of printed wiring boards (PWBs) and fabrication of highly dense electrical circuit layers are needed to realize the miniaturization and densification of the semiconductor package PWBs. Micro-drilling technology has been attracing attention to machine the electronic micro-through holes with an ultra-high-speed spindle, more than 160 krpm. However, problems have emerged; the drill tool bends and suffers breakage in the drilling process and the heat damage around the drilled hole after a drilling process occurs due to the increase in the drilling aspect ratio between hole depth and diameter. In general, a step feed drilling method is considered an effective way to solve these problems. However, short stroke alternating motion in the spindle axis is needed to do the step drilling process and its motion causes various kinds of vibration. We constructed a machine tool with a novel counter balance mechanism in the spindle driving Z-axis and investigated a model to estimate a proper balance mass for the step drilling process. We compared the frequency response results from a proposed model with the experimental ones, and discussed a control on vibration due to the counter balance mechanism. The results demonstrate that a proposed vibration proof method was found to reduce the vibration in high-speed step-micro-drilling motion and to improve the drilled hole quality and the efficiency of micro-drilling process in the PWB manufacturing fields.
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Tanaka, Hidetake, and Mitsuru Kitamura. "Machinability of Thermo-Plastic Carbon Fiber Reinforced Plastic in Inclined Planetary Motion Milling." International Journal of Automation Technology 12, no. 5 (September 5, 2018): 750–59. http://dx.doi.org/10.20965/ijat.2018.p0750.
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The study deals with an improved method of milling thermo-plastic CFRP with a radius end mill. The authors use inclined planetary milling to carry out a fine CFRP boring technique. The inclined planetary motion milling consists of the two independent spindle motions of tool rotation and revolution. The eccentricity of the tool rotation axis is realized by a few degrees of inclination from the revolution axis. The movement of eccentric mechanism can be reduced by comparing it with that of orbital drilling. The inclined planetary motion milling reduces inertial vibration and decreases cutting force. Owing to the geometrical cutting principle, material delamination and burrs can be decreased. Thermo-plastic CFRP has recently been under development as an alternative structural material for the next generation of automobiles and in response to demands for bored fastening holes. The shape of the cutting edge of the ball end mill is suitable for the inclined planetary milling, as revealed by results of past experiments done on thermo-set CFRP. However, the ball end mill has left burrs and melted matrix on the exit side in the case of thermo-plastic CFRP. The radius end mill has the advantage over the ball end mill in terms of finishing fine boring. Based on the consideration of the schematic model and experiments using the Taguchi method, the improved milling conditions are examined.
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Shirahama, Yusaku, Ryuta Sato, Yusuke Takasuka, Hidenori Nakatsuji, and Keiichi Shirase. "Machine Bed Support with Sliding Surface for Improving the Motion Accuracy." International Journal of Automation Technology 10, no. 3 (May 2, 2016): 447–54. http://dx.doi.org/10.20965/ijat.2016.p0447.
Повний текст джерелаАнотація:
The purpose of this study is to develop a new machine bed support mechanism for reducing the vibration generated during the high-speed tracking motion of numerical control machine tools. In order to achieve this, the frequency response and motion trajectory of a machine tool with the proposed machine bed, which has a sliding surface, are measured and compared with that of the conventional support. Based on the modal analysis of the machine tool structure, a mathematical model representing the influence of the machine bed characteristics on the vibration is also developed. The model consists of a bed, saddle, table, column, and spindle head. Every component has three degrees of freedom for each of the translational and rotational axes. In order to evaluate the characteristics of the machine bed, the mathematical model determines the stiffness and damping along the X-, Y-, and Z-axis between the bed and the ground. The frequency response curves simulated by using the mathematical model are compared with that of the measured ones. From the results of the experiments and simulations, it is confirmed that the vibration generated during high-speed tracking motions can be reduced by using the proposed machine bed with a sliding surface.
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Lin, Shen Yung, and Bing Hsueh Yang. "Experimental Study of Cutting Performance for Inconel 718 Milling by Various Assisted Machining Techniques." Solid State Phenomena 294 (July 2019): 129–34. http://dx.doi.org/10.4028/www.scientific.net/ssp.294.129.
Повний текст джерелаАнотація:
The five stage experiments including without assistance, single and hybrid assisted machining systems on Inconel 718 milling were conducted in this study. First of all, the milling experiment without assistance was performed to investigate the variations of cutting performance and the results were used for a suitable process parameter planning in the subsequent stage experiments. Next, a laser assisted system was introduced in the second stage where the spacing distance between the laser spot and cutting-tool along the cutting direction was modified to test whether laser preheating may effectively reduce the cutting force. A biaxial ultrasonically assisted system with only one-axis oscillation (x or y direction) and with two-axis simultaneous oscillations (x and y directions) were subsequently introduced at the third to fourth stage experiments, respectively. While a biaxial ultrasonically and the laser assisted systems were integrated together to construct a hybrid assisted cutting system at the last stage experiment. Under these assistances, milling experiments of Inconel 718 by cutting-tool of tungsten carbide with nanoSi® coating were conducted. And the full-factorial experiments of process parameter combinations such as spindle speed, radial cutting depth and feed rate were planned. The results indicated that the laser-preheating assisted system could effectively reduce the cutting force as well as enhance the cutting performance. The effect of the biaxial ultrasonic oscillation on tool service life could greatly be promoted. Furthermore, the cutting performance exhibited in the integrated hybrid assisted milling prevails over that in milling without assistance as well as with each single assisted system. Under this hybrid assisted milling, the better surface roughness of 0.216μm was obtained under a combination of spindle speed of 6000 rpm, radial cutting depth of 0.01 mm, and feed rate of 300mm/min, accompanied by a maximum cutting-tool wear of 13.849μm.
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Song, Qing Hua, Xing Ai, Wei Xiao Tang, and Yi Wan. "Prediction of Multiple Frequencies Chatter Stability in High-Speed Milling System." Key Engineering Materials 375-376 (March 2008): 564–68. http://dx.doi.org/10.4028/www.scientific.net/kem.375-376.564.
Повний текст джерелаАнотація:
A new dynamics model for multi-degree of freedom high-speed milling system is proposed, which takes account of regenerative effects and the effects of the relative vibration of spindle axis in milling process. Based on the mode synthesis theory and the zeroth-order approximation of the Fourier series, an integrated stability analytical method for multiple frequencies is presented, which involves multiple orders modal characteristics and higher order excitations in high-speed milling process. The chatter stability lobes are predicted in the frequency domain using the proposed stability analytical method, and verified by milling experiments. It is shown that stability regions involving multiple natural modes are reduced contrary to the case of single natural mode.
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Kitamura, Akihiro, Ichiro Takahashi, Masahiro Anzai, and Yoshimi Takeuchi. "Development of Die Mold Processing Machine with Multi-Spindles and Axes." International Journal of Automation Technology 1, no. 2 (November 5, 2007): 94–102. http://dx.doi.org/10.20965/ijat.2007.p0094.
Повний текст джерелаАнотація:
Within the high quality Metal Mold Manufacturing industry there is a continuing effort to reduce overall costs and shorten lead time from design to completion. This is particularly true in the Automotive Industry where model change over has become more frequent. The molds required for automotive type three dimensional shaped exteriors and interiors are typically in the range of 2400 mm X 4800 mm and can weigh up to 19 tons. Currently, the processing of these large-scale molds requires the material to be put on the table of a machine tool that has a long travel and a bed length of more than twice the travel. By using large-scale horsepower, low spindle speeds and slow feed rates the mold is generated. The dynamics of this industry led to the development of a truly original, unparalleled machine tool. This multi-head, large-scale mold processing machine was found to feature a 40-50% decrease in the processing time required for mold manufacture. The newly developed machine has a range of 1-4 heads allowing a variety of different curved surfaces to be processed at the same time, on the same mold. The multi-tasking capability of this machine tool results in quality improvement and over all cost reduction.
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Zhou, Xin, Lars Penter, Steffen Ihlenfeldt, and Ulrike Jehring. "The Damping Effect of Particle-Filled Hollow Sphere Structures and their Application in Machine Tool Components." Materials Science Forum 1053 (February 17, 2022): 218–24. http://dx.doi.org/10.4028/p-9qy2yb.
Повний текст джерелаАнотація:
High speed feed axes are a key for increasing the productivity of machine tools. It requires high acceleration and causes jerk, which excites the machine structure and negatively affects the process quality. One approach to reduce those machine vibrations are passive dampers such as particle-filled hollow spheres (PHS). PHSs dissipate vibration energy through relative motion and friction between particles among themselves and the sphere. Compounds of PHS as core of sandwich materials allow structure-integrated damping of machine tool components and for maintaining a high specific stiffness at the same time. The complex interactions within each sphere lead to nonlinear damping. As of today, precise predictions on how PHSs influence the overall machine behavior are not possible. This prognosis is essential for establishing the material in any machine structure. The paper investigates the damping properties of PHSs in a spindle box of a machine tool. The experimental and numeric analysis demonstrates the nonlinear behavior and shows the reaction of the spindle box under external excitation. The result shows that the damping of the spindle box with PHSs is frequency and amplitude dependent. The damping of PHSs is domain with increased parts of them deformed during vibration.
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Ma, Wei, Zhan Feng Si, and Yong Jian Yu. "Non-Linear Bearing Force of the Bearing and its Influence on Vibration of Spindle-Bearing System." Applied Mechanics and Materials 741 (March 2015): 416–20. http://dx.doi.org/10.4028/www.scientific.net/amm.741.416.
Повний текст джерелаАнотація:
In order to study the influence of the non-linear bearing force on the vibration of spindle bearing system, non-linear bearing force is deduced in the working state of the rolling bearing. Non-linear dynamic equations of a system are established and the numerical method is used to solve the equations. The system axis path chart, the bifurcation diagram and the Poincare figure are drawn in Matlab and used to analyze the characteristics of the system vibration with the different parameters. The results show that the change of the non-linear bearing force will cause the vibration of the system and bifurcation phenomena will appear in the system. Speed and damping are important parameters that influence the vibration form. By choosing reasonable working parameters the vibration of system can be reduced and the stability of the system can be improved.
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Triebe, Matthew J., Fu Zhao, and John W. Sutherland. "Development of a Cost Model for Vertical Milling Machines to Assess Impact of Lightweighting." Journal of Manufacturing and Materials Processing 5, no. 4 (December 1, 2021): 129. http://dx.doi.org/10.3390/jmmp5040129.
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Lightweighting is a design strategy to reduce energy consumption through the reduction of mass of a product. Lightweighting can be applied to machine tools to reduce the amount of energy consumed during the use phase. Thus, the energy cost of machine operation will be reduced. One might also hypothesize that since a lighter-weight machine tool requires less material to build, the cost to produce such a machine will be less. However, it may also be the case that lightweighting a machine tool increases its complexity, which will likely drive up the cost to manufacture the machine. To explore the cost drivers associated with building a machine tool, data on the features associated with a wide variety of vertical milling machine tools are collected. Then, empirical cost models are fit to this data. The results from the cost models show that the machine tool mass is a significant cost driver; other key drivers are the number of axes and spindle power. The models are used to predict the cost benefits of lightweighting in terms of mass, which are compared to potential increased manufacturing costs associated with complexities introduced due to lightweighting.
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N. Srinivasan and M. Gunasekaran. "FIELD CONTROL OF LEAF ROT DISEASE OF COCONUT WITH FUNGICIDES." CORD 12, no. 02 (December 1, 1996): 34. http://dx.doi.org/10.37833/cord.v12i02.303.
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Leaf rot is a disease of fungal complex super imposed on root (wilt) affected coconut palms in India. A field fungicidal control trial on the disease involving contact (indofil M‑45, Fytolan) and systemic (Calixin) fungicides was conducted Fungicidal treatments, spraying of Indofil M‑45 and pouring of Calixin into axil of spindle, were found beneficial as the disease intensity reduced in newly emerged leaves. However, the extent of disease amelioration by fungicides was marginal to moderate level only. Importance of broad spectrum fungicide(s) and measures of disease protection are outlined.
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Kausar, Zareena, Muhammad Faizan Shah, Zeeshan Masood, Hafiz Zia Ur Rehman, Sardor Khaydarov, Muhammad Tallal Saeed, Omid Razmkhah, and Haseeb Yaqoob. "Energy Efficient Parallel Configuration Based Six Degree of Freedom Machining Bed." Energies 14, no. 9 (May 5, 2021): 2642. http://dx.doi.org/10.3390/en14092642.
Повний текст джерелаАнотація:
The process of material removal from a workpiece to obtain the desired shape is termed machining. Present-day material removal technologies have high spindle speeds and thus allow quick material removal. These high-speed spindles are highly exposed to vibrations and, as a result, the accuracy of the final workpiece’s dimensions is compromised. To overcome this problem, the motion of the tool is restricted, and multiple degrees of freedom are given through the motion of the workpiece in different axes. A machining bed configured as a parallel manipulator capable of giving six degrees of freedom (DOF) to the workpiece is proposed in this regard. However, the proposed six DOF machining bed should be energy efficient to avoid an increase in machining cost. The benefit of using the proposed configuration is a reduction in dimensional error and computational time which, as a result, reduces the energy utilization, vibrations, and machining time in practice. This paper presents kinematics, dynamics and energy efficiency models, and the development of the proposed configuration of the machining bed. The energy efficiency model is derived from the dynamics model. The models are verified in simulation and experimentally. To minimize error and computation time, a PID controller is also designed and tested in simulation as well as experimentally. The resulting energy efficiency is also analyzed. The results verify the efficacy of the proposed configuration of the machining bed, minimizing position error to 2% and reducing computation time by 27%, hence reducing the energy consumption and enhancing the energy efficiency by 60%.
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Masmiati, N., H. S. Chan, Ahmed A. D. Sarhan, M. A. Hassan, and M. Hamdi. "Investigating the Possibility to Reduce the Residual Stress Level in 2.5D Cutting Using Titanium Coated Carbide Ball End Mill." Advances in Materials Science and Engineering 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/485267.
Повний текст джерелаАнотація:
End milling is a multipoint cutting process in which material is removed from a workpiece by a rotating tool. It is widely used in cutting 2.5D profiles such as point-to-point, contouring, and pocketing operations. 2.5D machining possesses the capability to translate in all 3 axes but can perform the cutting operation in only 2 of the 3 axes at a time. This study focuses on optimizing the cutting parameters, such as machined surface inclinationangle, axial depth of cut, spindle speed, and feed rate for better surface integrity, namely, microhardness, residual stress, and microstructure in 2.5D cutting utilizing a titanium-coated carbide ball end mill. An optimization method known as Taguchi optimization, which includes planning, conducting, and analyzing results of matrix experiments, was used in order to achieve the best cutting parameter level. Data analysis was conducted using signal-to-noise (S/N) and target performance measurement (TPM) response analysis and analysis of variance (Pareto ANOVA). The optimum condition results obtained through analysis show improvements in microhardness of about 0.7%, residual stress in the feed direction of about 18.6%, and residual stress in the cutting direction of about 15.4%.
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Azim, Shakir, Sahar Noor, Qazi Salman Khalid, Aqib Mashood Khan, Danil Yurievich Pimenov, Imran Ahmad, Abdur Rehman Babar, and Catalin I. Pruncu. "Sustainable Manufacturing and Parametric Analysis of Mild Steel Grade 60 by Deploying CNC Milling Machine and Taguchi Method." Metals 10, no. 10 (September 29, 2020): 1303. http://dx.doi.org/10.3390/met10101303.
Повний текст джерелаАнотація:
Design and manufacturing are the key steps in the sustainable manufacturing of any product to be produced. Within the perspective of injection molds production, increased competitiveness and repeated changes in the design require a complete optimized manufacturing process. Local and minor improvements in the milling process do not generally lead to an optimized manufacturing process. The goal of the new geometry and parametric analysis of the mould is to reduce the quality issues in mild steel grade 60. In this explicit research, the surface roughness (smoothness) of indigenously produced injection moulds in the local market in Pakistan is investigated. The CNC milling machine (five-axis) is used for the manufacturing of an injection mould, and the Taguchi method of the design of the experiment is applied for parameters optimization. Hence, the overall process is assisted in balancing the milling machine parameters to trim down the surface roughness issue in mild steel moulds and increase their sustainability. The spindle speed (rpm), the depth of cut (mm), and the feed rate (mm/rev) are considered as input variables for process optimization, and the experiments are performed on mild steel grade 60. It is deduced that the combination of a spindle speed of 800 rpm, feed rate of 10 mm/rev and depth of cut of 0.5 mm is the best case in case of minimum surface roughness, which leads to sustainable products. It is also deduced from ANOVA, that the spindle speed is a factor that affects the surface roughness of mild steel products, while the feed rate turns out to be insignificant.
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Li, Qiang, and Ling Jiang Ouyang. "Process Optimization of CNC End Milling of Integral Impeller Channels." Applied Mechanics and Materials 268-270 (December 2012): 1469–73. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.1469.
Повний текст джерелаАнотація:
The process optimization model was established in finish machining of the bottom surface of the integral impeller channels. The optimization objective was the maximal productivity, and three process parameters such as spindle speed, feed speed and cutter row space are chosen as design variables. Constrains were analyzed from three aspects: machine tool, cutter and machining quality in accordance with the actual 5-axis machining conditions. The genetic algorithm (GA) was employed to seek the optimum solution. A machining experiment was conducted to compare the efficiency of the optimum parameters with that of the empirical parameters. The results showed that the optimum solution reduced by 29.4% time in comparison with the empirical parameters, which represented that the process optimization was significant in improving the finish machining efficiency of impeller channels.
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Rodriguez-Alabanda, Oscar, Maria Bonilla, Guillermo Guerrero-Vaca, and Pablo Romero. "Selection of Parameters and Strategies to Reduce Energy Consumption and Improve Surface Quality in EN-AW 7075 Molds Machining." Metals 8, no. 9 (August 31, 2018): 688. http://dx.doi.org/10.3390/met8090688.
Повний текст джерелаАнотація:
The machining of cavities for blow molding is a long and costly process, with the objective of obtaining an excellent surface finish with the minimal possible electrical energy consumption (EEC). This work has studied which combination of cutting parameters and cutting strategies to use to achieve an optimum surface finish on the mold using the minimal associated EEC: in roughing operation, tool path strategy and axial depth of cut were studied; in finishing operation, tool path strategy, spindle-speed, feed-rate, and step-over were evaluated. Thirty-two molds were machined in blocks of aluminium alloy EN-AW 7075 T6 in a machining center of a three-axis, following an orthogonal design of experiments. The analysis of results demonstrates that: a roughing strategy has influence on the surface roughness on the bottom of the mold; a finishing strategy is an influential factor on the surface roughness on the walls of the mold; certain parameters have no relevance on the surface roughness but have an influence on the EEC; an adequate selection of cutting strategies and cutting parameters permit an improvement of surface roughness of up to 70%, and a reduction of 40% in EEC, compared to the less favorable tests.
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Saeed, Muhammad Junaid, Can Liu, and Umair Riaz. "Experimental Study on Investigating the Influence of Combination Combining Eccentricity with Different Orientations for Process System of Milling Center." Journal of Advanced Manufacturing Systems 19, no. 02 (June 2020): 389–410. http://dx.doi.org/10.1142/s0219686720500195.
Повний текст джерелаАнотація:
There are several critical factors which have adverse effects on the workpiece surface finish, dimensional accuracy, tool life, etc. Eccentricity is one of them which can be manipulated when the spindle, tool holder and milling cutter revolve around the line parallel to their cutting axes and crop up due to clamping deviation and geometric imperfections. This work was driven by the observation that there should an approach through which final eccentric error can be reduced as other researchers only displayed the effects of eccentricity on cutting forces, etc. This task was carried out through performing numerous experiments on the CNC milling center and measuring geometric imperfections from the whole body of machining elements at different orientations with dial gauge to find out whether different orientations of elements have effects on the eccentricity. If they have noticeable effects then such orientations of elements exhibiting the minimum eccentricity can be selected which in turn may improve the accuracy and precision of workpieces and reduce the final cutting edge error. Our observation showed that orientations have remarkable effects on the eccentricity pretending lowest final eccentric error which is unable to be ignored.
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Miao, Lianjie, Jingjing Li, Jian Li, Yangyang Lu, David Shieh, Joseph E. Mazurkiewicz, Margarida Barroso, et al. "Cardiomyocyte orientation modulated by the Numb family proteins–N-cadherin axis is essential for ventricular wall morphogenesis." Proceedings of the National Academy of Sciences 116, no. 31 (July 12, 2019): 15560–69. http://dx.doi.org/10.1073/pnas.1904684116.
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The roles of cellular orientation during trabecular and ventricular wall morphogenesis are unknown, and so are the underlying mechanisms that regulate cellular orientation. Myocardial-specific Numb and Numblike double-knockout (MDKO) hearts display a variety of defects, including in cellular orientation, patterns of mitotic spindle orientation, trabeculation, and ventricular compaction. Furthermore, Numb- and Numblike-null cardiomyocytes exhibit cellular behaviors distinct from those of control cells during trabecular morphogenesis based on single-cell lineage tracing. We investigated how Numb regulates cellular orientation and behaviors and determined that N-cadherin levels and membrane localization are reduced in MDKO hearts. To determine how Numb regulates N-cadherin membrane localization, we generated an mCherry:Numb knockin line and found that Numb localized to diverse endocytic organelles but mainly to the recycling endosome. Consistent with this localization, cardiomyocytes in MDKO did not display defects in N-cadherin internalization but rather in postendocytic recycling to the plasma membrane. Furthermore, N-cadherin overexpression via a mosaic model partially rescued the defects in cellular orientation and trabeculation of MDKO hearts. Our study unravels a phenomenon that cardiomyocytes display spatiotemporal cellular orientation during ventricular wall morphogenesis, and its disruption leads to abnormal trabecular and ventricular wall morphogenesis. Furthermore, we established a mechanism by which Numb modulates cellular orientation and consequently trabecular and ventricular wall morphogenesis by regulating N-cadherin recycling to the plasma membrane.
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Baker, D. A., and C. J. Maday. "Design of Noninteracting Multivariable Feedback Control Systems Without Decoupling Filters." Journal of Engineering for Gas Turbines and Power 107, no. 4 (October 1, 1985): 845–50. http://dx.doi.org/10.1115/1.3239821.
Повний текст джерелаАнотація:
The design of multivariable control systems for modern applications is an important challenge to the control system engineer. Active control of metal machining operations, control of gas turbine operations, and chemical process control are current areas of interest. In precision machining operations where tolerances of a few microinches are required, in-process control with several servos will be required. These servos could control spindle axis location and tool position about several axes, thus forming a multi-input/multi-output system. Modern gas turbines, required to operate over more extended regimes, are provided with multiple controls, e.g., nozzle settings and fuel flows which must be implemented in some rational manner. In the chemical process industries, there are many examples of multivariable systems with several control variables and several desired or controlled outputs. One control approach considers a separate system for each of the controlled variables, so that a change in one input will produce an interaction effect that must be managed by another separate system. This approach is attractive and straightforward to implement, but current practice shows significant coupling effects. In order to reduce or eliminate interaction, a control algorithm, with strong integral compensation, for a sixth-order, two-input, two-output linear plant with dynamic coupling is proposed. Decoupling filters are not used. The primary goal is to realize a substantial reduction in the coupling effects when a step input is used for a single variable. A secondary goal is to achieve deadbeat response for the controlled variable to the step input. Moreover, these goals are to be attained in the presence of significant changes in the system parameters or in the presence of arbitrary external disturbances, i.e., robustness is required. The control strategy uses cascaded integral error compensation that permits conceptual division of the network so that two single-input/single-output systems result. Coupling effects are treated as arbitrary disturbances. Poles for each loop are placed on the real axis in the left-half plane. Numerical solutions to the system equations show that this approach produces a system that achieves effective decoupling and robustness simultaneously. It is significantly superior to Proportional-Integral-Derivative controllers which also are considered in detail.
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Houliston, E., D. Carre, J. A. Johnston, and C. Sardet. "Axis establishment and microtubule-mediated waves prior to first cleavage in Beroe ovata." Development 117, no. 1 (January 1, 1993): 75–87. http://dx.doi.org/10.1242/dev.117.1.75.
Повний текст джерелаАнотація:
The single axis (oral-aboral) and two planes of symmetry of the ctenophore Beroe ovata become established with respect to the position of zygote nucleus formation and the orientation of first cleavage. Bisection of Beroe eggs at different times revealed that differences in egg organisation are established in relation to the presumptive oral-aboral axis before first cleavage. Lateral fragments produced after but not before the time of first mitosis developed into larvae lacking comb-plates on one side. Time-lapse video demonstrated that waves of cytoplasmic reorganisation spread through the layer of peripheral cytoplasm (ectoplasm) of the egg during the 80 minute period between pronuclear fusion and first cleavage, along the future oral-aboral axis. These waves are manifest as the progressive displacement and dispersal of plaques of accumulated organelles around supernumerary sperm nuclei, and a series of surface movements. Their timing and direction of propagation suggest they may be involved in establishing cytoplasmic differences with respect to the embryonic axis. Inhibitor experiments suggested that the observed cytoplasmic reorganisation involves microtubules. Nocodazole and taxol, which prevent microtubule turnover, blocked plaque dispersal and reduced surface movements. The microfilament-disrupting drug cytochalasin B did not prevent plaque dispersal but induced abnormal surface contractions. We examined changes in microtubule organisation using immunofluorescence on eggs fixed at different times and in live eggs following injection of rhodamine-tubulin. Giant microtubule asters become associated with each male pronucleus after the end of meiosis. Following pronuclear fusion they disappear successively, those nearest the zygote nucleus shrinking first, to establish gradients of aster size within single eggs. Regional differences in microtubule behaviour around the time of mitosis were revealed by brief taxol treatment, which induced the formation of small microtubule asters in the region of the nucleus or spindle during both first and second cell cycles. The observed wave of change may thus reflect the local appearance and spreading of mitotic activity as the zygote nucleus approaches mitosis.
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Zhu, Aibin, Hongling Wu, Yulei Yang, and Shengli He. "A general performance calculation model of journal bearing using unified coordinate system." Industrial Lubrication and Tribology 70, no. 4 (May 8, 2018): 782–88. http://dx.doi.org/10.1108/ilt-05-2017-0144.
Повний текст джерелаАнотація:
Purpose Because of the various geometric descriptions of different bearing types, performance calculation of journal bearing is complicated, and is difficult in traditional model. This paper aims to simplify the calculation of the journal bearing performance, and to reduce the workload. Design/methodology/approach On the basis of previous research, a general performance calculation model of journal bearing is proposed in this paper. Eccentricity ratio and attitude angle of axis to each pad are calculated by coordinates of spindle center and each pad center by establishing the unified coordinate system. The surface deformation of journal bearing is taken into consideration, and a correction value is added to the dimensionless oil film thickness. Findings The performance calculation results of various fix-pad and tilting-pad journal bearings match the results of the existing references very well, revealing the validity of the model. The general model can greatly reduce programming workload, and increase adaptability to different bearings. Originality/value Geometric descriptions of both fix-pad and tilting-pad journal bearings are unified in this model, which can be applied to both standard and non-standard journal bearings with different preload ratios. In addition, due to the unification of different bearings types, this model is more conducive to performance comparison among different bearing types, and promotes the development of new structural forms for journal bearings.
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Chevychelov, S. A., M. V. Snopkov, I. V. Bondartsev, and A. V. Maslennikov. "DIAGRAM OF FIXTURE FOR VIBRATION DRILLING OF HOLES IN COMPOSITE MATERIALS." Proceedings of the Southwest State University 21, no. 6 (December 28, 2017): 76–84. http://dx.doi.org/10.21869/2223-1560-2017-21-6-76-84.
Повний текст джерелаАнотація:
This paper discusses the use of vibration drilling method for hole making in composite materials. The special feature of advanced composite materials is the difficulty of machining by conventional methods. The occurrence of defects such as matrix cracking, delamination and fibers failure, thermal degradation of matrix obtained in the process of making holes requires the development of new technological solutions and special equipment and tooling. As an alternative, along with cutting and abrasive machining methods for composite materials, we can consider vibration drilling, laser, ultrasonic and abrasive blasting machining of holes. The Department of Engineering Technologies and Equipment of Southwest State University has made a device intended for vibration drilling of holes in composite materials. Using the proposed method allows us to reduce the vibrations along the drill axis, both in the low-frequency and high-frequency range (20 to 500 Hz). It also allows us to change the frequency of vibration without stopping the cutting process. The device is designed for metall cutting machines related to drilling-and-boring group of machines with a vertical spindle to increase performance and improve the quality of holes shaping. Technical specifications of the designed device provide the set tool advances, the required frequency of spindle rotation, giving the necessary cutting speed (they depend on technical features of the selected machine), as well as the necessary amplitude and high frequency axial oscillations of the tool. To convert electric oscillations into mechanical ones there has been adopted the scheme of two inductance coils, being placed one above the other. The proposed method of electro-impulse drilling will solve the problem of processing composite materials (matrix cracking, delamination and fiber failures) and improve the quality and productivity of making holes in composite materials.
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Arif, Muhammad, Mustafizur Rahman, Yoke San Wong, and Kui Liu. "Micro-Ball Endmilling of Tungsten Carbide for Micro-Molding and Prototyping Applications." Key Engineering Materials 516 (June 2012): 591–94. http://dx.doi.org/10.4028/www.scientific.net/kem.516.591.
Повний текст джерелаАнотація:
This paper presents micro-ball end milling of tungsten carbide using a CBN cutter to investigate its capability for machining slots for micro-moulds. Crack-free slots were machined at different axial depths of cut by inclining the work piece surface at different angles to the spindle axes to study the influence of these machining parameters on the cutting mechanism and surface finish. The experimental results show that up to 150 µm deep slots can be finished efficiently on tungsten carbide work pieces without leaving any fracture marks. It was identified that the chip disposal ability of micro-ball end milling reduced with increase in axial depth of cut. The cutting action was more efficient in up milling cuts compared to that in down milling when machining a slot. The inclination of the work piece proved propitious for machining slots with high-quality finish on tungsten carbide work pieces and a larger inclination angle also facilitated chip disposal.
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Dan, Ioan, and Romeo Cioară. "Methods to Increase the Rigidity of the C-Frame of a Press." Applied Mechanics and Materials 371 (August 2013): 183–87. http://dx.doi.org/10.4028/www.scientific.net/amm.371.183.
Повний текст джерелаАнотація:
Reducing exploitation energy consumption for any technical system is an effective way, which is in complete accordance with the concept of sustainable development [1]. The presses, particularly the mechanical ones, are machine tools with a long-term exploitation [2]. At these ones, the operating energy consumption, significant in value, decreases only if the rigidity of the structure of resistance increases, including that of the frame. Several analytical models, developed and studied by the authors, confirmed the hypothesis that a solution to increase the rigidity of a mechanical press with open frame is obtained by shortening it. Moreover, it occurs also a slight decrease in material consumption integrated into the frame, which is a favourable effect. There have been developed more new constructive solutions [3, 4], characterized by minimal changes to the reference design solution, that of the press frame PAI 25. The new suggested constructive solutions are obtained as 3D models, accomplished in Pro Engineer Wildfire 4, and the finite element analysis was made in Catia V5 R16. The present paper shows results on increasing stiffness and reducing stress state for a few constructive solutions of shortened C-frame, having reduced distance between the working surface of the table and the spindle bore axis.
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Elfying, D. C. "EFFECTS OF TREE SUPPORT AND TRAINING SYSTEM ON APPLE TREE GROWTH AND PRODUCTIVITY." HortScience 27, no. 6 (June 1992): 620a—620. http://dx.doi.org/10.21273/hortsci.27.6.620a.
Повний текст джерелаАнотація:
'Empire' (E) and 'Marshall McIntosh' (MM)/'Mark' trees planted in 1986 were trained to the freestanding central leader (CL), central leader with annual extension-shoot heading (HCL), slender spindle (SS) or vertical axis (VA). Support with a full tree stake (SS & VA) had little effect on shoot growth. HCL increased shoot number and mean length. Fewer pruning cuts were made on supported trees, while more were made on HCL trees. Dry weight of prunings 1989-91 was the same for all MM trees, while in E trees, CL and SS had lower pruning weights than HCL and VA. Bloom density was uninfluenced by support or training. Fruit set was greater in 1990 and 1991 on supported E trees, and in 1990 on supported MM trees. Yield was greater on supported systems in 3 out of 4 production years. Total yield after 6 years of age was 26-38% greater for supported trees of both cultivars. Bienniality was reduced about 15% by support in MM trees but unaffected by support or training in E trees. Net total crop value (estimated annual crop value minus annual harvest cost and support cost, if applicable, annual 10% discount rate) in 1991 was approximately $1600 per ha greater for supported E trees and $270 per ha greater for supported MM trees.
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Borradaile, Nica M., and J. Geoffrey Pickering. "Polyploidy impairs human aortic endothelial cell function and is prevented by nicotinamide phosphoribosyltransferase." American Journal of Physiology-Cell Physiology 298, no. 1 (January 2010): C66—C74. http://dx.doi.org/10.1152/ajpcell.00357.2009.
Повний текст джерелаАнотація:
Polyploid endothelial cells are found in aged and atherosclerotic arteries. However, whether increased chromosome content has an impact on endothelial cell function is unknown. We show here that human aortic endothelial cells become tetraploid as they approach replicative senescence. Furthermore, accumulation of tetraploid endothelial cells was accelerated during growth in high glucose. Interestingly, induction of polyploidy was completely prevented by modest overexpression of the NAD+ regenerating enzyme, nicotinamide phosphoribosyltransferase (Nampt). To determine the impact of polyploidy on endothelial cell function, independent of replicative senescence, we induced tetraploidy using the spindle poison, nocodazole. Global gene expression analyses of tetraploid endothelial cells revealed a dysfunctional phenotype characterized by a cell cycle arrest profile (decreased CCNE2/A2, RBL1, BUB1B; increased CDKN1A) and increased expression of genes involved in inflammation ( IL32, TNFRSF21/10C, PTGS1) and extracellular matrix remodeling ( COL5A1, FN1, MMP10/14). The protection from polyploidy conferred by Nampt was not associated with enhanced poly(ADP-ribose) polymerase-1 or sirtuin (SIRT) 2 activity, but with increased SIRT1 activity, which reduced cellular reactive oxygen species and the associated oxidative stress stimulus for the induction of polyploidy. We conclude that human aortic endothelial cells are prone to chromosome duplication that, in and of itself, can induce characteristics of endothelial dysfunction. Moreover, the emergence of polyploid endothelial cells during replicative aging and glucose overload can be prevented by optimizing the Nampt-SIRT1 axis.
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Yu, Won-Dong, Yu-Jin Kim, Min-Jeong Cho, Gi-Jin Kim, Soon-Ha Kim, Myung-Joo Kim, Jung-Jae Ko, and Jae-Ho Lee. "MIT-001 Restores Human Placenta-Derived Mesenchymal Stem Cells by Enhancing Mitochondrial Quiescence and Cytoskeletal Organization." International Journal of Molecular Sciences 22, no. 10 (May 11, 2021): 5062. http://dx.doi.org/10.3390/ijms22105062.
Повний текст джерелаАнотація:
Inflammation is a major cause of several chronic diseases and is reported to be recovered by the immuno-modulation of mesenchymal stem cells (MSCs). While most studies have focussed on the anti-inflammatory roles of MSCs in stem cell therapy, the impaired features of MSCs, such as the loss of homeostasis by systemic aging or pathologic conditions, remain incompletely understood. In this study, we investigated whether the altered phenotypes of human placenta-derived MSCs (hPD-MSCs) exposed to inflammatory cytokines, including TNF-α and IFN-γ, could be protected by MIT-001, a small anti-inflammatory and anti-necrotic molecule. MIT-001 promoted the spindle-like shape and cytoskeletal organization extending across the long cell axis, whereas hPD-MSCs exposed to TNF-α/IFN-γ exhibited increased morphological heterogeneity with an abnormal cell shape and cytoskeletal disorganization. Importantly, MIT-001 improved mitochondrial distribution across the cytoplasm. MIT-001 significantly reduced basal respiration, ATP production, and cellular ROS levels and augmented the spare respiratory capacity compared to TNF-α/IFN-γ-exposed hPD-MSCs, indicating enhanced mitochondrial quiescence and homeostasis. In conclusion, while TNF-α/IFN-γ-exposed MSCs lost homeostasis and mitochondrial quiescence by becoming over-activated in response to inflammatory cytokines, MIT-001 was able to rescue mitochondrial features and cellular phenotypes. Therefore, MIT-001 has therapeutic potential for clinical applications to treat mitochondrion-related inflammatory diseases.