Artigos de revistas sobre o tema "Ω-automates"
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Brkić, Dejan, e Zoran Stajić. "EXCEL VBA-BASED USER DEFINED FUNCTIONS FOR HIGHLY PRECISE COLEBROOK’S PIPE FLOW FRICTION APPROXIMATIONS: A COMPARATIVE OVERVIEW". Facta Universitatis, Series: Mechanical Engineering 19, n.º 2 (11 de julho de 2021): 253. http://dx.doi.org/10.22190/fume210111044b.
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This review paper gives Excel functions for highly precise Colebrook’s pipe flow friction approximations developed by users. All shown codes are implemented as User Defined Functions – UDFs written in Visual Basic for Applications – VBA, a common programming language for MS Excel spreadsheet solver. Accuracy of the friction factor computed using nine to date the most accurate explicit approximations is compared with the sufficiently accurate solution obtained through an iterative scheme which gives satisfying results after sufficient number of iterations. The codes are given for the presented approximations, for the used iterative scheme and for the Colebrook equation expressed through the Lambert W-function (including its cognate Wright ω-function). The developed code for the principal branch of the Lambert W-function has additional and more general application for solving different problems from variety branches of engineering and physics. The approach from this review paper automates computational processes and speeds up manual tasks.
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Sasaki, H., H. Nishinaka e K. Shida. "Automated measurement system for 1-Ω standard resistors using a modified Wheatstone bridge". IEEE Transactions on Instrumentation and Measurement 40, n.º 2 (abril de 1991): 274–77. http://dx.doi.org/10.1109/tim.1990.1032936.
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Ouameur, Mohamed, Renata Vasconcellos e Mohamed Agazar. "Digital Impedance Bridge for Four-Terminal-Pair AC Resistor Calibration up to 20 kHz". Metrology 4, n.º 1 (4 de janeiro de 2024): 1–14. http://dx.doi.org/10.3390/metrology4010001.
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For this study, a substitution principle-based impedance bridge has been developed to calibrate AC resistors in a four-terminal-pair (4TP) configuration. The calibration is performed in the full complex plane for resistances ranging from 100 mΩ to 400 Ω and frequencies of between 50 Hz and 20 kHz. The automated bridge is based on four resistors associated with two high-impedance stages. The balancing of the bridge is achieved by means of PXI modules. The bridge is automatically balanced via a simplex top-down algorithm. The new bridge is primarily used for the measurement chain of AC standard resistors defined in a 4TP configuration at LNE, which are used for routine customer calibrations. The traceability of LNE’s standard resistors when defined in a 4TP configuration is ensured by a measurement chain from a 1 kΩ reference resistor using the new bridge. The reference resistor was calibrated previously via comparison with a calculable resistor up to 20 kHz. The bridge was validated via comparison with calibration results obtained in 1983 and 2009. For a resistor of 1 Ω at 1 kHz, the uncertainty of the series resistance variation and the phase shift are less than 6 µΩ/Ω (k = 1) and 6 µrad (k = 1), respectively.
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De Rosa, Pierluigi, Andrea Fredduzzi e Corrado Cencetti. "Stream Power Determination in GIS: An Index to Evaluate the Most ’Sensitive’Points of a River". Water 11, n.º 6 (31 de maio de 2019): 1145. http://dx.doi.org/10.3390/w11061145.
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This paper focuses on the problem of measuring stream power in a hydrographic network using the original definition provided by Bagnold in 1996. Recent digital elevation models have enabled the calculation of channel gradients and, consequently, stream power with a finer spatial resolution, and this has created promising and novel opportunities to investigate river geomorphological processes and forms. The work carried out in this study includes defining and implementing a methodological approach that could be automated within a geographic information system and that meets two requirements: (1) it uses a DEM as input data at a suitable resolution; (2) it estimates the stream power Ω , as well as its variability along the considered stream, in the best possible way using available data. In particular, the methodological approach was implemented in a GIS environment (GRASS GIS) and applied to a sample basin to highlight the variability in Ω along the main stream and its most important tributaries. The sudden and more substantial variations in stream power were then related to the processes acting in the fluvial system. This approach made it possible to highlight how erosion, solid transport, and sedimentation phenomena occurring along the fluvial reaches are related to abrupt variations (increase/decrease) in the “power” available. The results of this study support the idea that the automated and standardized screening of stream power variability along a stream can be used as a preliminary diagnostic element to identify the most “sensitive” points of the stream on which to concentrate subsequent investigations (field checks to verify the causes), with the aim of mitigating risks due to the dynamics of the riverbed.
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Nie, Pei, Bin Pan, Muhammd Jamil Ahmad, Xinxin Zhang, Chao Chen, Zhiqiu Yao, Haimiao Lv, Ke Wei e Liguo Yang. "Summer Buffalo Milk Produced in China: A Desirable Diet Enriched in Polyunsaturated Fatty Acids and Amino Acids". Foods 11, n.º 21 (2 de novembro de 2022): 3475. http://dx.doi.org/10.3390/foods11213475.
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The objective of the study was to compare and reveal differences in basic chemical parameters, fatty acids, amino acids, and lipid quality indices of crossbred buffalo (swamp x river type) milk produced in summer and winter. The buffalo milk samples were collected in summer (Jul–Aug) and winter (Dec–Jan) from Hubei province, China. The samples were detected by using CombiFoss apparatus, gas chromatography, and an automated specialized amino acid analyzer. The results showed that the basic chemical parameters, fatty acid profiles, lipid quality indices, and amino acid profiles of crossbred buffalo milk differed between summer and winter. Specifically, summer buffalo milk exhibited a higher content of MUFA (monounsaturated fatty acids) and PUFA (polyunsaturated fatty acids) than winter buffalo milk. Summer buffalo milk had a lower content of major SFA (saturated fatty acids), a higher content of ω-3 and DFA (hypocholesterolemic fatty acids), a lower ω-6/ω-3 ratio, a higher value of 3 unsaturated fatty acid indices (C14, C16, C18), and a lower value of IA (index of atherogenicity) and IT (index of thrombogenicity) than winter buffalo milk. Additionally, 17 amino acids, including 8 EAA (essential amino acids) and 9 NEAA (non-essential amino acids) were higher in summer buffalo milk. These results indicated that summer buffalo milk was more health-beneficial than winter buffalo milk. Therefore, summer buffalo milk might be a desirable diet option for human nutrition and health. Our findings provide valuable information for the research and development of buffalo dairy products in China or other Asian countries.
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Štambuk, Igor. "Precison Automated Measuring System for Accurate Comparison of Resistance Standards and Shunts". Journal of Energy - Energija 67, n.º 1 (2 de junho de 2022): 19–22. http://dx.doi.org/10.37798/201867187.
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In this paper we will present a development of Measurement system for accurate comparison of low resistance standards and AC shunts ranging from 0.1 mΩ to 10 Ω as well as system testing and use. The system consists of a specially built current source, range selector, current reversal module and low cost analog to digital converter. The entire measurement procedure is automated and controlled by LabVIEW program. Subsequent testing has shown that the realized precision resistance measurement system has achieved precision comparable to more expensive commercial devices. The system or system elements can be used both in smart grid applications and in military laboratories for testing new technologie.
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Ritter, Benedikt, Andreas Vogt e Tibor J. Dunai. "Technical Note: Noble gas extraction procedure and performance of the Cologne Helix MC Plus multi-collector noble gas mass spectrometer for cosmogenic neon isotope analysis". Geochronology 3, n.º 2 (19 de agosto de 2021): 421–31. http://dx.doi.org/10.5194/gchron-3-421-2021.
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Abstract. We established a new laboratory for noble gas mass spectrometry that is dedicated to the development and application to cosmogenic nuclides at the University of Cologne (Germany). At the core of the laboratory are a state-of-the-art high-mass-resolution multicollector Helix MC Plus (Thermo Fisher Scientific) noble gas mass spectrometer and a novel custom-designed automated extraction line. The mass spectrometer is equipped with five combined Faraday multiplier collectors, with 1012 and 1013 Ω pre-amplifiers for faraday collectors. We describe the extraction line and the automated procedure for cosmogenic neon and the current performance of the experimental set-up. Performance tests were conducted using gas of atmospheric isotopic composition (our primary standard gas), as well as CREU-1 intercomparison material, containing a mixture of neon of atmospheric and cosmogenic composition. We use the results from repeated analysis of CREU-1 to assess the performance of the current experimental set-up at Cologne. The precision in determining the abundance of cosmogenic 21Ne is equal to or better than those reported for other laboratories. The absolute value we obtain for the concentration of cosmogenic 21Ne in CREU is indistinguishable from the published value.
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Wang, Xiaodong. "Simultaneous measurement of pole figure and residual stress for polycrystalline thin films: ω–φ′ compensated grazing-incidence diffraction in side-inclination mode". Journal of Applied Crystallography 54, n.º 5 (29 de setembro de 2021): 1424–36. http://dx.doi.org/10.1107/s1600576721008335.
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A new grazing-incidence diffraction (GID) measurement geometry between in plane and out of plane is proposed. It is improved from the previous ω–φ compensated GID in side-inclination mode for measurement of residual stress in polycrystalline thin films [Wang & van Riessen (2017). Powder Diffr. 32, S9–S15]. Instead of keeping a constant azimuthal direction of the incident beam on the thin film sample, the current proposed variation maintains a constant azimuthal direction of the scattering vector projection on the thin film sample. The variation is named `ω–φ′ compensated GID in side-inclination mode' and enables d-spacing measurements along the same azimuthal direction. An Excel spreadsheet is included for readers to plan the measurement and to calculate the residual stress for the planned sample azimuthal direction. Anisotropic residual stresses of a polycrystalline NiFe thin film on an Si 001 substrate are measured by combining this method with phi rotations. Highly automated data analysis templates are developed using DIFFRAC.TOPAS v7 launch mode to calculate residual stress for all planned azimuthal directions sequentially. A pole figure file in simple text format is also generated from the same data set using DIFFRAC.TOPAS v7 launch mode, and can be directly imported into DIFFRAC.TEXTURE v4.1 for further texture analysis. Corrections for the incident-beam refraction have been implemented in both data analysis models.
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Potap, О. Yu, e А. V. Ivanichyk. "The accuracy of rolling thickness adjustment in conditions of high-frequency disturbances taking into account the speed of roll setting devices". Fundamental and applied problems of ferrous metallurgy 36 (2022): 299–307. http://dx.doi.org/10.52150/2522-9117-2022-36-299-307.
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In the continuous mills, where the strip thickness at the entrance contains a high-frequency component caused by the eccentricity of the rolls of the previous cage, the effectiveness of AGC-systems for regulating the thickness of the rolled product depends on the speed of operation of hydraulic roll setting devices (HRSD). Analytical substantiation of the transfer functions of the AGC-system by the eccentricity of the rolls and by the thickness of the undercut, taking into account the real speed of the HRSD has been carried out. The frequency characteristics of the AGC-system are analytically determined. It has been proven that with the available speed of the HPD in the interval of rotation frequencies of the support rolls inherent in cold rolling (ω= 5 – 15 s-1), the amplitude-frequency characteristic (AFC) of the AGC-system is almost linear. AFC depending on the time constant T of the HRSD and the ratio of the modulus of rigidity of the rolling strip MΠ to the modulus of rigidity of the rolling stand МK varies within wide limits from A(5)=0.05 (at ω = 5s-1; T=0.01 s; MΠ/MK = 1) to A(15)=0.48 (at ω = 15 s-1; T = 0.01 s; MΠ/MK = 4). At the same time, the thickness variation at the outlet of the cage meets the requirements for thin cold-rolled products of high precision. It has been proved that under the conditions of regulation of the thickness of the rolling strip according to the AGC-algorithm the amplitude of the oscillations of the rolled thickness caused by the eccentricity of the rolls is smaller than the amplitude of the oscillations of the roll gap caused by the eccentricity and decreases with an increase in the rotation frequency of the rolls and the time constant of the HRSD according to a close to linear law. Such linearity creates the basis for the application of adaptive algorithms for determining the actual amplitude of fluctuations of the roll gap in automated systems for compensating the eccentricity of the rolls.
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Buchmeier, Guilherme Germano, Alexandru Takacs, Daniela Dragomirescu, Juvenal Alarcon Ramos e Amaia Fortes Montilla. "Optimized NFC Circuit and Coil Design for Wireless Power Transfer with 2D Free-Positioning and Low Load Sensibility". Sensors 21, n.º 23 (2 de dezembro de 2021): 8074. http://dx.doi.org/10.3390/s21238074.
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This paper proposes a method for optimizing and designing a wireless power transfer system operating at 13.56 MHz. It can be used as guidelines for designing coils for the new-trending technology that enables NFC devices to not only to communicate but also to charge. Since NFC wireless charging is an emerging technology, it is of interest to propose optimizations and a dedicated circuit design for such systems. This work proposes an optimization procedure to calculate the dimensions of a transmitter and receiver pair that assures the highest efficiency while considering all possible positions of a receiver that is placed on a desired surface. This procedure seeks to facilitate and automate the design of rectangular-shaped coils, whereas the literature proposes mainly square-shaped coils. Afterwards, a circuit analysis was conducted, and the series-parallel compensation network is proposed as the most promising topology of the receiver to assure a low efficiency sensibility to load variations for 13.56 MHz wireless power transfer systems. A pair of optimized transmitter and receiver coils is prototyped, and the experimental results are tested against the theory. The transmitter of 7 cm×11.4 cm and receiver of 4 cm ×4 cm are separated by 10 mm. The receiver can move on a surface of 8 cm ×12 cm and the load can vary from 36 Ω to 300 Ω while assuring a minimum and maximum efficiency of 80% and 88.3%, respectively.
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Abdullahi, M., L. S. Kuburi, P. T. Zubairu, U. Jabo, A. A. Yahaya e Y. James. "Effect of Heat Treatment and Sulfuric Acid Anodization on Corrosion Resistance of Aluminum Alloy (AA7075)". Nigerian Journal of Technology 40, n.º 1 (23 de março de 2021): 56–62. http://dx.doi.org/10.4314/njt.v40i1.9.
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This paper, studied the effect of heat treatment and anodization on corrosion resistance of aluminum alloy 7075 (AA7075), with a view to improving its corrosion resistance. Microstructure and micro hardness of the anodic film of the samples were studied with the aid of optical metallurgical microscope and automated micro hardness testing machine. Linear polarization methods were used to assess the corrosion behaviour of the alloy in 0.5M HCl. The microstructure of the annealed sample showed formation of dendrites while precipitation hardened samples in palm kernel oil and SAE 40 engine oil showed precipitates of MgZn2. The SEMS result showed pores and micro cracks on the surfaces of the anodized samples, with the as cast and anodized sample in sulfuric acid exhibiting most compact with few pores. The as cast and sulfuric acid anodized sample shows highest micro hardness value of 205.33 HV, while the least value of 150.67 HV was recorded in sample precipitation hardened in SAE 40 engine oil and anodized in sulfuric acid. Analysis of the potentiodynamic polarization data and curves showed a linear relationship (decrease in icorr, decreases the corrosion rate) between current density and the corrosion rate in all the samples. Higher polarization resistance of 15.093 Ω/cm2 was recorded by the as cast and Sulfuric acid (SA) anodized sample while the precipitation treated in SAE 40 engine oil plus SA anodized sample recorded lowest polarization resistance of 5.2311 Ω/cm2. Heat treatment alone improves corrosion resistance of AA 7075 in 0.5 M HCl solution but heat treatment plus SA anodization does not improve corrosion resistance in the same environment.
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Serrano-Pérez, Javier, Inocencia Pacheco-Chávez, Monica Araceli Camacho-González, Omar Serrano-Pérez e Jaime Pacheco-Martínez. "Dip-coater revolver machine for layer processing on metallic substrates". Pädi Boletín Científico de Ciencias Básicas e Ingenierías del ICBI 11, Especial5 (15 de dezembro de 2023): 109–16. http://dx.doi.org/10.29057/icbi.v11iespecial5.11694.
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This work presents the design and construction of a dip-coater revolver machine to manufacture homogeneous coatings on metallic substrates. The material used for the fabrication of the machine structure was 6061-T6 aluminum. A Nema 23 stepper motor of 4.2 A and 24 V with a speed reducer with a 10:1 ratio that can provide an angular velocity ω between 1-80 rpm was used for the motion system. DC linear actuator was used for the immersion process, which operates in the range of 12-24 V at 7 A, with a stroke length of 50 mm and a maximum linear speed of 12 mm/s. For the coating tests, SayerLack® black and white base paint was used on 6061-T6 aluminum substrates and 304 stainless steel substrates. Finally, the mathematical model and the simulation of an automatic PID control system were carried out to automate the coating manufacturing process.
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Pâris, Isabelle, Patrick Petitjean, Éric Aubourg, Adam D. Myers, Alina Streblyanska, Brad W. Lyke, Scott F. Anderson et al. "The Sloan Digital Sky Survey Quasar Catalog: Fourteenth data release". Astronomy & Astrophysics 613 (maio de 2018): A51. http://dx.doi.org/10.1051/0004-6361/201732445.
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We present the data release 14 Quasar catalog (DR14Q) from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV). This catalog includes all SDSS-IV/eBOSS objects that were spectroscopically targeted as quasar candidates and that are confirmed as quasars via a new automated procedure combined with a partial visual inspection of spectra, have luminosities Mi [z = 2] < −20.5 (in a Λ CDM cosmology with H0 = 70 km s−1 Mpc−1, Ω M =0.3, and Ω Λ = 0.7), and either display at least one emission line with a full width at half maximum larger than 500 km s−1 or, if not, have interesting/complex absorption features. The catalog also includes previously spectroscopically-confirmed quasars from SDSS-I, II, and III. The catalog contains 526 356 quasars (144 046 are new discoveries since the beginning of SDSS-IV) detected over 9376 deg2 (2044 deg2 having new spectroscopic data available) with robust identification and redshift measured by a combination of principal component eigenspectra. The catalog is estimated to have about 0.5% contamination. Redshifts are provided for the Mg II emission line. The catalog identifies 21 877 broad absorption line quasars and lists their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03 mag. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra, covering the wavelength region 3610–10 140 Å at a spectral resolution in the range 1300 < R < 2500, can be retrieved from the SDSS Science Archiver Server.
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Zhang, Dongliang, e Hanming Tao. "Bearing Fault Diagnosis Based on Parameter-Optimized Variational Mode Extraction and an Improved One-Dimensional Convolutional Neural Network". Applied Sciences 14, n.º 8 (13 de abril de 2024): 3289. http://dx.doi.org/10.3390/app14083289.
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When faults occur in rolling bearings, vibration signals exhibit sensitivity to periodic impact components, susceptibility to complex background noise, and non-stationary and nonlinear characteristics. Consequently, using traditional signal processing methods to effectively identify bearing faults presents significant challenges. To facilitate the accurate fault diagnosis of bearings in noisy conditions, we propose an intelligent fault diagnosis method using the Archimedes optimization algorithm (AOA), coupled with a one-dimensional multi-scale residual convolutional neural network (1D-MRCNN), to optimize the variational mode extraction (VME) parameters. First, we introduce a weighted correlated kurtosis (WCK) indicator, formulated using the correlation coefficient and correlated kurtosis as the objective function, to optimize the VME’s center frequency ω and penalty factor α, enabling targeted signal extraction. Second, deep learning techniques are employed to construct the 1D-MRCNN. The neural network then processes the extracted signal for feature extraction and automated fault-type identification. Our simulation results show that the WCK objective function effectively isolates impact components under fault conditions, and our experimental validation confirms that the proposed method accurately identifies diverse fault types across multiple noise levels.
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Norman, Charles E., Elias M. Absi e Raye E. Thomas. "Solar-grade silicon substrates by a powder-to-ribbon process". Canadian Journal of Physics 63, n.º 6 (1 de junho de 1985): 859–62. http://dx.doi.org/10.1139/p85-139.
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A new technique for producing silicon ribbons for solar-cell substrates is described. The process begins with inexpensive, 98% pure silicon that is crushed and acid leached to raise the purity to 99.9%. This powder is spread on a graphite plate and electron-beam annealed to form a flat, self-supporting "preribbon." After removal of the graphite and unmelted powder, the preribbon is given a second electron-beam scan that recrystallizes the silicon into a smooth polycrystalline ribbon. This zone melting further improves the purity to over 99.99%.Ribbons 0.4 mm thick and up to 16 mm wide were produced in this initial work. The ribbons are p-type, 0.07 Ω∙cm, and have long crystals about 1 mm wide. Electron-diffusion lengths of 20–30 μm were measured. Calculations indicate that solar-cell efficiencies up to 13% should be possible. If the process can be scaled up and automated, the cost of volume production could be as low as 43 cents/W. It is concluded that the process has the potential for achieving low-cost "solar-grade" substrates and has advantages over other processes. Further work is planned.
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Eggers, C., A. Holstein, C. Schneider, D. J. Pedrosa, M. Dietlein, C. Kobe, L. Timmermann, M. Schmidt e D. Kahraman. "123I-FP-CIT SPECT imaging of the dopaminergic state". Nuklearmedizin 51, n.º 06 (2012): 244–51. http://dx.doi.org/10.3413/nukmed-0449-11-12.
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Summary123I-N-ω-fluoropropyl-2β-carbomethoxy-3β- (4-iodophenyl)nortropan (123I-FP-CIT) single photon emission computed tomography (SPECT) can be evaluated by both visual assessment and quantitative analysis to assess the striatal dopamine state in vivo. The aim of our study was to investigate if visual assessment according to a predefined image grading scale reflects the results of quantitative assessment techniques. Patients, methods: 195 patients with a clinical diagnosis of idiopathic Parkinson's disease (n = 134), atypical parkinsonian syndrome (n = 47) or essential tremor (n = 14) were examined with 123I-FP-CIT SPECT and included in this retrospective study. Results were analysed according to predefined visual patterns of dopaminergic degeneration and graded as normal (grade 5) or abnormal (grade 1–4) independently by three raters. Quantitative two-dimensional (2D) operator-dependent, manual and three-dimensional (3D) operator- independent, automated approaches were used for quantitative analysis of the specific 123I-FP-CIT tracer binding ratio (SBR) for caudate and putamen. Results: Sensitivity, specificity, PPV, NPV and diagnostic accuracy of visual assessment of 123I-FP-CIT SPECT for the diagnosis of a neuro degenerative Parkinson's syndrome were 99%, 86%, 99%, 86% and 98%, respectively. Visual assessment and quantitative analysis agreed well in evaluating the degree of dopaminergic degeneration. Significant differences (p < 0.001) were found between degeneration patterns. Only between the so-called eagle wing degeneration and the normal pattern no significant differences in SBR caudate and putamen were found, neither by the quantitative manual (p = 1.00; p = 0.196) nor by the quantitative automated method (p = 1.0; p = 0.785). Inter-rater agreement for visual assessment was substantial for all possible pairs of the three raters (κ = 0.70 to 0.74). Strong correlations were observed between the quantitative manual and quantitative automated methods for quantification of SBR caudatum (r = 0.920, r2 = 0.846, p < 0.001) and SBR putamen (r = 0.908, r2 = 0.824, p < 0.001). Conclusion: Visual assessment was highly consistent with the results obtained by quantitative analysis and showed a substantial inter-rater agreement between experienced and inexperienced raters. Our findings indicate that visual assessment might be a reliable analysis approach for clinical routine.
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Ahnström, Josefin, Helena M. Andersson, Kevin Canis, Eva Norstrøm, Yao Yu, Björn Dahlbäck, Maria Panico, Howard R. Morris, James T. B. Crawley e David A. Lane. "Activated protein C cofactor function of protein S: a novel role for a γ-carboxyglutamic acid residue". Blood 117, n.º 24 (16 de junho de 2011): 6685–93. http://dx.doi.org/10.1182/blood-2010-11-317099.
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Abstract Protein S has an important anticoagulant function by acting as a cofactor for activated protein C (APC). We recently reported that the EGF1 domain residue Asp95 is critical for APC cofactor function. In the present study, we examined whether additional interaction sites within the Gla domain of protein S might contribute to its APC cofactor function. We examined 4 residues, composing the previously reported “Face1” (N33S/P35T/E36A/Y39V) variant, as single point substitutions. Of these protein S variants, protein S E36A was found to be almost completely inactive using calibrated automated thrombography. In factor Va inactivation assays, protein S E36A had 89% reduced cofactor activity compared with wild-type protein S and was almost completely inactive in factor VIIIa inactivation; phospholipid binding was, however, normal. Glu36 lies outside the ω-loop that mediates Ca2+-dependent phospholipid binding. Using mass spectrometry, it was nevertheless confirmed that Glu36 is γ-carboxylated. Our finding that Gla36 is important for APC cofactor function, but not for phospholipid binding, defines a novel function (other than Ca2+ coordination/phospholipid binding) for a Gla residue in vitamin K–dependent proteins. It also suggests that residues within the Gla and EGF1 domains of protein S act cooperatively for its APC cofactor function.
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Zeng, Lifang, Dingyi Pan, Shangjun Ye e Xueming Shao. "A fast multiobjective optimization approach to S-duct scoop inlets design with both inflow and outflow". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, n.º 9 (24 de agosto de 2018): 3381–94. http://dx.doi.org/10.1177/0954410018795806.
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A fast multiobjective optimization method for S-duct scoop inlets considering both inflow and outflow is developed and validated. To reduce computation consumption of optimization, a simplified efficient model is proposed, in which only inflow region is simulated. Inlet pressure boundary condition of the efficient model is specified by solving an integral model with both inflow and outflow. An automated optimization system integrating the computational fluid dynamics analysis, nonuniform rational B-spline geometric representation technique, and nondominated sorting genetic algorithm II is developed to minimize the total pressure loss and distortion at the exit of diffuser. Flow field is numerically simulated by solving the Reynolds-averaged Navier–Stokes equation coupled with k–ω shear stress transport turbulence model, and results are validated to agree well with previous experiment. S-duct centreline shape and cross-sectional area distribution are parameterized as the design variables. By analyzing the results of a suggested optimal inlet chosen from the obtained Pareto front, total pressure recovery has increased from 97% to 97.4%, and total pressure distortion DC60 has decreased by 0.0477 (21.7% of the origin) at designed Mach number 0.7. The simplified efficient model has been validated to be reliable, and by which the time cost for the optimization project has been reduced by 70%.
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Hammer, Christof, Johannes Warmer, Stephan Maurer, Peter Kaul, Ronald Thoelen e Norbert Jung. "A Compact 16 Channel Embedded System with High Dynamic Range Readout and Heater Management for Semiconducting Metal Oxide Gas Sensors". Electronics 9, n.º 11 (5 de novembro de 2020): 1855. http://dx.doi.org/10.3390/electronics9111855.
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The simultaneous operation of multiple different semiconducting metal oxide (MOX) gas sensors is demanding for the readout circuitry. The challenge results from the strongly varying signal intensities of the various sensor types to the target gas. While some sensors change their resistance only slightly, other types can react with a resistive change over a range of several decades. Therefore, a suitable readout circuit has to be able to capture all these resistive variations, requiring it to have a very large dynamic range. This work presents a compact embedded system that provides a full, high range input interface (readout and heater management) for MOX sensor operation. The system is modular and consists of a central mainboard that holds up to eight sensor-modules, each capable of supporting up to two MOX sensors, therefore supporting a total maximum of 16 different sensors. Its wide input range is archived using the resistance-to-time measurement method. The system is solely built with commercial off-the-shelf components and tested over a range spanning from 100 Ω to 5 GΩ (9.7 decades) with an average measurement error of 0.27% and a maximum error of 2.11%. The heater management uses a well-tested power-circuit and supports multiple modes of operation, hence enabling the system to be used in highly automated measurement applications. The experimental part of this work presents the results of an exemplary screening of 16 sensors, which was performed to evaluate the system’s performance.
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Nobrega, Raphael Borges, Valmir Nascimento Júnior, Ítalo Oliveira Medeiros, Edson Guedes Costa e Ronimack Trajano Souza. "Concepção de um sistema de automação e monitoramento para equipamento utilizado em ensaios de trilhamento elétrico e erosão". Revista Principia - Divulgação Científica e Tecnológica do IFPB 1, n.º 48 (3 de março de 2020): 33. http://dx.doi.org/10.18265/1517-03062015v1n48p33-45.
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<p>This paper aimed at the design and development of a data acquisition and control system using the Arduino open-source platform to automate equipment responsible for the IEC 60587 electrical tracking and erosion test. The developed system allows the selection of protection resistors specified by the standard from the voltage value informed by the operator, monitoring of the leakage current flowing over five samples simultaneously tested and automatically interrupts the samples if the leakage current exceeds 60 mA for more than two seconds. The leakage current values are measured indirectly from the voltage drop across 50 Ω shunt resistors installed in series with each sample. The voltage values on the shunt resistors are conditioned by a measuring circuit that allows the voltage level to be adjusted to the analog inputs of the microcontroller, ie, between 0 V and 5 V. The microcontroller treatment performs the voltage signal obtained by the measuring circuit, the calculation of the RMS value of the current and stop criterion monitoring the leakage current. The calibration of the leakage current measurement circuit was performed by comparing voltage values measured by a digital oscilloscope for four different alternate waveforms and values up to 5 Vrms, corresponding to currents up to 100 mA. The results showed that the circuit provided measurements close to the values measured by the oscilloscope, with errors below 11%. For current values between 30 mA and 80 mA, the errors were less than 6%.</p>
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Florido, Emmanuel A., e Sarah Allyssa Solidum. "Butane/Propane Gas Sensing Using Zinc Oxide Film Grown by Successive Ionic Layer Adhesion and Reaction". Key Engineering Materials 705 (agosto de 2016): 273–77. http://dx.doi.org/10.4028/www.scientific.net/kem.705.273.
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This study was aimed to test the ability of zinc oxide (ZnO) film fabricated by successive ionic layer adsorption and reaction (SILAR) to detect liquid petroleum gas consisting of a mixture of butane/propane gas. The film was fabricated by alternate dipping of pre-cleaned glass substrates in a sodium zincate bath and in a 95°C hot water bath using an automated dipping machine to control the sequence and dipping time. Scanning electron microscopy (SEM) revealed a uniform film consisting of wurtzite ZnO nanorods for the sample grown using 0.1M concentration of sodium zincate and 200 dippings. Current-voltage characterization of the samples showed an average resistivity of 1.343 Ω-m. EDS analysis of the film confirmed the existence of zinc oxide with 65.9% zinc and 34.1% oxygen. The ZnO film exhibited an ability to detect the gas with an average gas response of 0.44, average response time of 14 seconds and average recovery time of 25 seconds using a gas concentration in air of 1.5 % by volume. Response time is the time for the sensor to reach the peak voltage output from the start of gas exposure while recovery time is the time for the voltage output to return to the initial value without gas when the gas is removed from the chamber. The zinc oxide film also showed a voltage output of 100, 109.31, 118.92, 123.61, 133.5, and 149.52 mV when exposed to percent volume gas concentrations of 0, 0.5, 0.75, 1.0, 1.25, and 1.5, respectively with a correlation coefficient of 0.97. The sensor sensitivity is 32 Δ(mV)/Δ(%conc).
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Esteves, David Seixas, Manuel F. C. Pereira, Ana Ribeiro, Nelson Durães, Maria C. Paiva e Elsa W. Sequeiros. "Development of MWCNT/Magnetite Flexible Triboelectric Sensors by Magnetic Patterning". Polymers 15, n.º 13 (29 de junho de 2023): 2870. http://dx.doi.org/10.3390/polym15132870.
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The fabrication of low-electrical-percolation-threshold polymer composites aims to reduce the weight fraction of the conductive nanomaterial necessary to achieve a given level of electrical resistivity of the composite. The present work aimed at preparing composites based on multiwalled carbon nanotubes (MWCNTs) and magnetite particles in a polyurethane (PU) matrix to study the effect on the electrical resistance of electrodes produced under magnetic fields. Composites with 1 wt.% of MWCNT, 1 wt.% of magnetite and combinations of both were prepared and analysed. The hybrid composites combined MWCNTs and magnetite at the weight ratios of 1:1; 1:1/6; 1:1/12; and 1:1/24. The results showed that MWCNTs were responsible for the electrical conductivity of the composites since the composites with 1 wt.% magnetite were non-conductive. Combining magnetite particles with MWCNTs reduces the electrical resistance of the composite. SQUID analysis showed that MWCNTs simultaneously exhibit ferromagnetism and diamagnetism, ferromagnetism being dominant at lower magnetic fields and diamagnetism being dominant at higher fields. Conversely, magnetite particles present a ferromagnetic response much stronger than MWCNTs. Finally, optical microscopy (OM) and X-ray micro computed tomography (micro CT) identified the interaction between particles and their location inside the composite. In conclusion, the combination of magnetite and MWCNTs in a polymer composite allows for the control of the location of these particles using an external magnetic field, decreasing the electrical resistance of the electrodes produced. By adding 1 wt.% of magnetite to 1 wt.% of MWCNT (1:1), the electric resistance of the composites decreased from 9 × 104 to 5 × 103 Ω. This approach significantly improved the reproducibility of the electrode’s fabrication process, enabling the development of a triboelectric sensor using a polyurethane (PU) composite and silicone rubber (SR). Finally, the method’s bearing was demonstrated by developing an automated robotic soft grip with tendon-driven actuation controlled by the triboelectric sensor. The results indicate that magnetic patterning is a versatile and low-cost approach to manufacturing sensors for soft robotics.
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Silva, D. F., A. F. C. Andrade, M. C. Caldas-Bussiere, E. C. C. Celeghini, M. A. Alonso, H. F. Carvalho, K. M. Lemes, S. A. Florez-Rodriguez, F. J. Affonso e R. P. Arruda. "246 EFFECT OF NITRIC OXIDE INHIBITION (N-ω-NITRO-L-ARGININE METHYL ESTER) AND SCAVENGER (METHYLENE BLUE) ON PLASMA MEMBRANE PEROXIDATION OF EQUINE CRYOPRESERVED SPERM". Reproduction, Fertility and Development 25, n.º 1 (2013): 271. http://dx.doi.org/10.1071/rdv25n1ab246.
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The peroxidation of plasma membrane lipids has been claimed to be a major factor involved in sublethal cryodamage. Some authors have reported that reactive oxygen species (ROS) accumulation could be an important factor leading to further damage in post-thaw sperm. Oxidative stress occurring in the sperm is a phenomenon associated with increased rate of oxidation of cellular components and excessive production of ROS and nitrogen. The objective of this study was to evaluate the effect of NO inhibition [N-ω-nitro-l-arginine methyl ester (l-NAME)] and scavenger (methylene blue) on the plasma membrane peroxidation of equine cryopreserved capacitated sperm. Three ejaculates were obtained from each of three stallions (n = 9). Semen was packaged into 0.5-mL straws to a concentration of 200 × 106 sperm mL–1 in BotuCrio® extender and frozen using an automated technique with a programmed machine. Four straws were thawed in a water bath at 37°C for 30 s and centrifuged in bovine IVF media supplemented with sodium bicarbonate and BSA for the capacitation of equine sperm. The supernatant was withdrawn, and semen was then incubated in the same media with l-arginine, with or without the NO synthase inhibitor, l-NAME, and in media with l-arginine with or without the NO scavenger, methylene blue: treatment (T)1 = control; T2 = 10 mM l-arginine (based on previous experiments); T3 = 1 mM l-NAME; T4 = 100 mM methylene blue; T5 = 10 mM l-arginine + 1 mM l-NAME; and T6 = 10 mM l-arginine + 100 mM methylene blue for 60, 120, and 300 min at 38°C under 5% CO2. After incubation, cells presenting membrane peroxidation were identified using an association of the fluorescent probes C11-BODIPY581/591 (1 mg mL–1; D-3861) and PI (0.5 mg mL–1; L0770). Nitric oxide production was identified using a 4,5-diaminofluorescein-2/diacetate (10 µM) probe associated with PI. The H33342 probe was used to avoid those particles presenting the same size and granularity as sperm cells being included in the counting. Both evaluations were performed using flow cytometry. Data were analysed by ANOVA, and the means were compared within each time with Tukey’s test, with a level of significance of 5%, using SAS software (SAS Institute Inc., Cary, NC, USA). Lipid peroxidation of the membrane was not influenced by the treatments at the different times (P > 0.05). This characteristic was reduced for the groups treated with methylene blue (T4 and T6) at times 60, 120, and 300 min compared with the other treated groups. Nitric oxide produced by sperm was not influenced by treatment at different times (P > 0.05). However, methylene blue addition was able to decrease NO production in treatments T4 and T6 at all the incubation times evaluated compared with the other treatments. Therefore, methylene blue removed NO and decreased plasma membrane lipid peroxidation, suggesting an antioxidant role of this scavenger. On the other hand, more research is needed to elucidate the mechanism of action of methylene blue on the physiology of cryopreserved equine sperm. Supported by FAPESP (grant 2009/54906-5).
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Miner, Samantha, Sawa Ito, Kazushi Tanimoto, Nancy F. Hensel, Fariba Chinian, Keyvan Keyvanfar, Christopher S. Hourigan et al. "Myeloid Leukemias Directly Suppress T Cell Proliferation Through STAT3 and Arginase Pathways". Blood 122, n.º 21 (15 de novembro de 2013): 3885. http://dx.doi.org/10.1182/blood.v122.21.3885.3885.
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Abstract The immune-editing effect of myeloid leukemia has recently been reported in several studies. We previously demonstrated that the K562 leukemia-derived cell line suppresses T cell proliferation, which suggests that myeloid leukemia may function in a similar way to myeloid derived suppressor cells (MDSC). While the mechanism of suppression in leukemia is not fully understood, recent murine and human studies suggest that the STAT3 and arginase pathways play a key role in the immunosuppressive function of MDSC. We hypothesized that myeloid leukemia utilizes the MDSC STAT3 and arginase pathway to evade immune control, and block anti-leukemic immune responses. To evaluate the suppressive capacity of myeloid leukemia on T cell proliferation, we isolated CD34+ blasts and myeloid derived suppressor cells (MDSC: CD11b+CD14+) from blood of primary leukemia samples by FACS sorting (n=5). These cells were co-cultured with CFSE-labeled CD4+ T cells (n=9), previously isolated from healthy donor PBMCs using an automated cell separator (RoboSep). After stimulating with CD3/CD28 Dynabeads (Invitrogen, New York, USA) for 72 hours, proliferation was measured by CFSE dilution of the viable cell population. In three myeloid leukemias studied, CD4+ T cell proliferation was significantly suppressed in the presence of primary CD34 blasts and MDSC cells (p<0.001). Interestingly, CD34 blasts demonstrated a greater suppressive effect on T cells compared to MDSC cells for these samples (not statistically significant p=0.61). Next we repeated the proliferation assay using five leukemia cell lines: THP-1 and AML1 (derived from AML), K562 and CML1 (derived from CML), and the Daudi lymphoid-derived leukemia cell line. After staining with cell tracer dye and irradiating 100Gy, the cells were co-incubated with CFSE-labeled CD4+ T cells from healthy volunteers (n=6). We found that CD4+ T cell proliferation in the presence of the myeloid leukemia cell lines was significantly suppressed (mean proliferation 5.7±0.9% to 26.1±10.7%: p<0.0001 to 0.05) compared to lymphoid cell lines (mean proliferation 76.3±8.2%: p>0.05), consistent with the results obtained with the primary leukemia samples. To evaluate the impact of STAT3 and arginase on the immunosuppressive function of myeloid leukemia, the five cell lines were primed overnight with either arginase inhibitor (N(ω)-Hydroxy-nor-L-arginine; EMD Biosciences, Inc., California, USA) or two STAT3 inhibitors (STAT3 Inhibitor VI or Cucurbitacin I; EMD Millipore, Massachusetts, USA). Then, CD4+ T cells from healthy donors (n=3) were cultured with either (1) leukemia without any inhibitor (2) leukemia in the presence of inhibitor (3) leukemia primed with inhibitor. Priming leukemia with arginase inhibitor and STAT3 inhibitors almost completely abrogated their suppressive effect of T cell proliferation (p<0.001). We conclude that myeloid leukemia, like MDSC, directly immunosuppresses T cells, through STAT-3 and arginase. This finding may underlie the immune-editing of T cells by myeloid leukemia. Our results suggest that STAT3 inhibitors could be used to augment leukemia-targeted immunotherapy. Further investigation of T cell biology within the leukemia microenvironment is needed to further define immune editing mechanisms in myeloid leukemia. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures: No relevant conflicts of interest to declare.
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Mohamed, Ouameur, Renata Vasconcellos, Agazar mohamed, Olivier Thévenot e Emmanuel Patois. "New impedance bridge at LNE for the two terminal-pair AC resistor calibration up to 20 kHz". Metrologia, 27 de julho de 2022. http://dx.doi.org/10.1088/1681-7575/ac8485.
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Abstract This paper presents the evolution of LNE’s impedance bridge (Wheatstone bridge) used to calibrate AC resistors defined in the two terminal-pair (2TP) configuration. A new automated Wheatstone bridge, based on 4 resistances, was developed to operate in the full complex plane for resistances ranging from 400 Ω to 2 MΩ and for frequencies up to 20 kHz. A commercial dual precision arbitrary waveform generator supplies the bridge and PXI modules achieve the balance. A phase and frequency synchronization solutions between the arbitrary waveform generator source and the PXI modules were used. The choice of these instruments allows the bridge to be easily automated and to benefit from recent progress in the development of digital analog converters, in particular those with high frequency sampling rates and resolution. The bridge is mainly dedicated to realize the periodic calibration of LNE’s standard resistors, used for routine customer calibrations. The traceability of LNE’s standard resistors is ensured, firstly, by the calibration of a 1 kΩ resistor by comparison to a calculable resistor up to 20 kHz. Then, this resistor is used as a reference element to ensure the traceability of all LNE’s standard resistors using the new bridge. The validation was done by comparing the results obtained, for some resistors with very low drift, with those obtained during calibrations performed in 1983, 1995 and 2009. For resistors of 1 kΩ in a 1:1 ratio, the expanded uncertainty of series resistance variation and argument are, respectively, less than 1.3 µΩ/Ω (k = 1) and 1.2 µrad (k = 1), up to 20 kHz.
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Pimsut, Yaowaret, Stephan Bauer, Marco Kraus, Ralf Behr, Mattias Kruskopf, Oliver F. Kieler e Luis Palafox. "Development and implementation of an automated four-terminal-pair Josephson impedance bridge". Metrologia, 2 de fevereiro de 2024. http://dx.doi.org/10.1088/1681-7575/ad2539.
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Abstract The four-terminal-pair impedance bridge using pulse-driven Josephson voltage standards at PTB has been fully automated. The same bridge configuration was employed to determine R:R and C:C ratios over the frequency range between 53 Hz to 50 kHz. Only minor changes are needed to cover this large frequency range: amplifiers to increase the sensitivities of the current detections for low frequencies and signal generators with higher resolutions at high frequencies to reach 50 kHz. Furthermore, the bridge can be operated for quadrature R:(1/ωC) measurements. The combined standard uncertainties (k = 1) for the new bridge were evaluated for all operating frequencies. They reach 2 nF/F and 4 nΩ/Ω at 1233.15 Hz. At this frequency, the 10 nF:10 nF ratio matched the ratio of PTB's bridge employing inductive voltage dividers within 1 nF/F ± 3 nF/F (k = 1). Over 45 days, the 10 nF:10 nF ratio deviated less than -2 nF/F ± 3 nF/F (k = 1). The 12.9 kΩ:10 kΩ ratio at 53 Hz differed -2 nΩ/Ω ± 5 nΩ/Ω (k = 1) from the DC ratio measured by the PTB's cryogenic current comparator bridge. Using a 12.9 kΩ resistance standard and a graphene AC quantum Hall resistance, the 10 nF:10 nF ratios derived from quadrature measurements agreed with the PTB's inductive voltage divider bridge better than 9 nF/F ± 13 nF/F (k = 1).
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Ghmati, Ramadan, e Mehdi Ghatus. "The Study of the Lift Coefficient of NACA-0012 Airfoil Subjected to an Incompressible Media by Using the Cartesian Cut Cell Method". مجلة الجامعة الأسمرية: العلوم التطبيقية 6, n.º 3 (3 de março de 2023). http://dx.doi.org/10.59743/aujas.v6i3.944.
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In order to shorten product design time, engineers need to create high quality meshes within a few days or hours. Newer automated techniques have been published to tackle this need, the Cartesian Cut Cell is one of them. This study is focused on the effect of different Cut Cell meshing strategies on the accuracy of aerodynamic performance predictions. The method can be described as a methodology in which Cut Cells are applied to the geometry utilizing a process involving rectangular/hexagonal cells on a regular lattice cutting through the geometry. The Cut Cell meshing is a general purpose designed for ANSYS FLUENT, making use of Workbench to construct the airfoil shape and the mesh. The results obtained for NACA-0012 are computed using two models available in ANSYS FLUENT, namely the Eq. 2 k-ω SST and the Eq. 3 k-kl-ω models. The three-dimensional numerical simulations were created for steady incompressible flow around NACA-0012 shape. Lift coefficient, Boundary layer thickness, mesh expansion ratio, and mesh density variation parameters were investigated. For this application both models produce good lift results. k-kl-ω produce better lift and the results are close to the measured data. The Cut Cell method showed a very good agreement between Computational Fluid Dynamics results and experimental data. This work illustrated that the Cartesian Cut Cell method has the ability to generate high quality mesh, which captures the details of the viscous boundary layer easily. The future work is to use more sophisticated turbulence models and mesh refinement for air craft wing with flap.
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Martín-Fernández, Manuel, Enrique Gracia e Marisol Lila. "A Short Measure of Acceptability of Intimate Partner Violence Against Women: Development and Validation of the A-IPVAW-8 Scale". Assessment, 18 de março de 2021, 107319112110001. http://dx.doi.org/10.1177/10731911211000110.
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Attitudes of acceptability of intimate partner violence against women (IPVAW) are considered one of the main risk factors of this type of violence. The aim of this study is to develop and validate a short version of the acceptability of IPVAW scale, the A-IPVAW-8, for large scale studies where space and time are limited. A panel of experts were asked to assess item content validity. Two samples were recruited to assemble an 8-item short version of the scale using automated test assembly, and to reassess the psychometric properties of the A-IPVAW-8 in an independent sample. Results showed that the A-IPVAW-8 had adequate internal consistency (α = .72-.76, ω = .73-.81), a stable one-factor latent structure (comparative fit index [CFI] = 0.94, Tucker–Lewis index = 0.92, root mean square error of approximation = 0.077), validity evidences based on its relationships to other variables in both samples, and was also invariant across gender (ΔCFI < |0.02|). This study provides a short, easy-to-use tool to evaluate attitudes of acceptability of IPVAW for large scale studies.
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Wang, Yilin, Enxiu Wu, Jirui Liu, Mengke Jia, Rui Zhang e Sen Wu. "Electrical characterization of an individual nanowire using flexible nanoprobes fabricated by atomic force microscopy-based manipulation". Nanotechnology and Precision Engineering 6, n.º 4 (12 de outubro de 2023). http://dx.doi.org/10.1063/10.0021195.
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Nanowires have emerged as promising one-dimensional materials with which to construct various nanocircuits and nanosensors. However, measuring the electrical properties of individual nanowires directly remains challenging because of their small size, thereby hindering the comprehensive understanding of nanowire-based device performance. A crucial factor in achieving reliable electrical characterization is establishing well-determined contact conditions between the nanowire sample and the electrodes, which becomes particularly difficult for soft nanowires. Introduced here is a novel technique for measuring the conductivity of an individual nanowire with the aid of automated nanomanipulation using an atomic force microscope. In this method, two nanowire segments cut from the same silver nanowire are positioned onto a pair of gold electrodes, serving as flexible nanoprobes to establish controllable contact with the sample. By changing the contact points along the nanowire sample, conductivity measurements can be performed on different regions, thereby eliminating the influence of contact resistance by analyzing multiple current–voltage curves. Using this approach, the resistivity of a 100-nm-diameter silver nanowire is determined to be 3.49 × 10−8 Ω m.
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Guo, Yueming, e Andrew R. Lupini. "Automatic and Quantitative Measurement of Spectrometer Aberrations". Microscopy and Microanalysis, 6 de setembro de 2023. http://dx.doi.org/10.1093/micmic/ozad084.
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Abstract The performance of electron energy loss spectrometers can often be limited by their electron optical aberrations. Due to recent developments in high energy resolution and momentum-resolved electron energy loss spectroscopy (EELS), there is renewed interest in optimizing the performance of such spectrometers. For example, the “ω − q” mode of momentum-resolved EELS, which uses a small convergence angle and requires aligning diffraction spots with the slot aperture, presents a challenge in the realignments of the spectrometer required by the adjustment of the projection lenses. Automated and robust alignment can greatly benefit such a process. The first step toward this goal is automatic and quantitative measurement of spectrometer aberrations. We demonstrate the measurement of geometric aberrations and distortions in EELS within a monochromated scanning transmission electron microscope (STEM). To better understand the results, we present a wave mechanical simulation of the experiment. Using the measured aberration and distortion coefficients as inputs to the simulation, we find a good match between the simulation and experiment, verifying formulae used in the simulation. From verified simulations with known aberration coefficients, we can assess the accuracy of measurements. Understanding the errors and inaccuracies in the procedure can guide further progress in aberration measurement and correction for new spectrometer developments.
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Raila, Tomas, Tadas Penkauskas, Filipas Ambrulevičius, Marija Jankunec, Tadas Meškauskas e Gintaras Valinčius. "AI-based atomic force microscopy image analysis allows to predict electrochemical impedance spectra of defects in tethered bilayer membranes". Scientific Reports 12, n.º 1 (21 de janeiro de 2022). http://dx.doi.org/10.1038/s41598-022-04853-4.
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AbstractAtomic force microscopy (AFM) image analysis of supported bilayers, such as tethered bilayer membranes (tBLMs) can reveal the nature of the membrane damage by pore-forming proteins and predict the electrochemical impedance spectroscopy (EIS) response of such objects. However, automated analysis involving pore detection in such images is often non-trivial and can require AI-based object detection techniques. The specific object-detection algorithm we used to determine the defect coordinates in real AFM images was a convolutional neural network (CNN). Defect coordinates allow to predict the EIS response of tBLMs populated by the pore-forming toxins using finite element analysis (FEA) modeling. We tested if the accuracy of the CNN algorithm affected the EIS spectral features sensitive to defect densities and other physical parameters of tBLMs. We found that the EIS spectra can be predicted sufficiently well, however, systematic errors of characteristic spectral points were observed and need to be taken into account. Importantly, the comparison of predicted EIS curves with experimental ones allowed to estimate important physical parameters of tBLMs such as the specific resistance of submembrane reservoir. This reservoir separates phospholipid bilayer from the solid support. We found that the specific resistance of the reservoir amounts to $$10^{4.25 \pm 0.10}$$ 10 4.25 ± 0.10 $$\Omega \cdot cm$$ Ω · c m which is approximately two orders of a magnitude higher compared to the specific resistance of the buffer bathing tBLMs studied in this work. We hypothesize that such effect may be related in part due to decreased concentration of ionic carriers in the submembrane due to decreased relative dielectric permittivity in this region.
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Yip, Mighten C., Mercedes M. Gonzalez, Christopher R. Valenta, Matthew J. M. Rowan e Craig R. Forest. "Deep learning-based real-time detection of neurons in brain slices for in vitro physiology". Scientific Reports 11, n.º 1 (16 de março de 2021). http://dx.doi.org/10.1038/s41598-021-85695-4.
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AbstractA common electrophysiology technique used in neuroscience is patch clamp: a method in which a glass pipette electrode facilitates single cell electrical recordings from neurons. Typically, patch clamp is done manually in which an electrophysiologist views a brain slice under a microscope, visually selects a neuron to patch, and moves the pipette into close proximity to the cell to break through and seal its membrane. While recent advances in the field of patch clamping have enabled partial automation, the task of detecting a healthy neuronal soma in acute brain tissue slices is still a critical step that is commonly done manually, often presenting challenges for novices in electrophysiology. To overcome this obstacle and progress towards full automation of patch clamp, we combined the differential interference microscopy optical technique with an object detection-based convolutional neural network (CNN) to detect healthy neurons in acute slice. Utilizing the YOLOv3 convolutional neural network architecture, we achieved a 98% reduction in training times to 18 min, compared to previously published attempts. We also compared networks trained on unaltered and enhanced images, achieving up to 77% and 72% mean average precision, respectively. This novel, deep learning-based method accomplishes automated neuronal detection in brain slice at 18 frames per second with a small data set of 1138 annotated neurons, rapid training time, and high precision. Lastly, we verified the health of the identified neurons with a patch clamp experiment where the average access resistance was 29.25 M$$\Omega$$ Ω (n = 9). The addition of this technology during live-cell imaging for patch clamp experiments can not only improve manual patch clamping by reducing the neuroscience expertise required to select healthy cells, but also help achieve full automation of patch clamping by nominating cells without human assistance.
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G. K., Anil Vishnu, Gayatri Gogoi, Midhun C. Kachappilly, Annapoorni Rangarajan e Hardik J. Pandya. "Label-free multimodal electro-thermo-mechanical (ETM) phenotyping as a novel biomarker to differentiate between normal, benign, and cancerous breast biopsy tissues". Journal of Biological Engineering 17, n.º 1 (13 de novembro de 2023). http://dx.doi.org/10.1186/s13036-023-00388-y.
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Abstract Background Technologies for quick and label-free diagnosis of malignancies from breast tissues have the potential to be a significant adjunct to routine diagnostics. The biophysical phenotypes of breast tissues, such as its electrical, thermal, and mechanical properties (ETM), have the potential to serve as novel markers to differentiate between normal, benign, and malignant tissue. Results We report a system-of-biochips (SoB) integrated into a semi-automated mechatronic system that can characterize breast biopsy tissues using electro-thermo-mechanical sensing. The SoB, fabricated on silicon using microfabrication techniques, can measure the electrical impedance (Z), thermal conductivity (K), mechanical stiffness (k), and viscoelastic stress relaxation (%R) of the samples. The key sensing elements of the biochips include interdigitated electrodes, resistance temperature detectors, microheaters, and a micromachined diaphragm with piezoresistive bridges. Multi-modal ETM measurements performed on formalin-fixed tumour and adjacent normal breast biopsy samples from N = 14 subjects were able to differentiate between invasive ductal carcinoma (malignant), fibroadenoma (benign), and adjacent normal (healthy) tissues with a root mean square error of 0.2419 using a Gaussian process classifier. Carcinoma tissues were observed to have the highest mean impedance (110018.8 ± 20293.8 Ω) and stiffness (0.076 ± 0.009 kNm−1) and the lowest thermal conductivity (0.189 ± 0.019 Wm−1 K−1) amongst the three groups, while the fibroadenoma samples had the highest percentage relaxation in normalized load (47.8 ± 5.12%). Conclusions The work presents a novel strategy to characterize the multi-modal biophysical phenotype of breast biopsy tissues to aid in cancer diagnosis from small-sized tumour samples. The methodology envisions to supplement the existing technology gap in the analysis of breast tissue samples in the pathology laboratories to aid the diagnostic workflow.