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Vanchikova, E. V., E. M. Lapteva, N. A. Vasilyeva, B. M. Kondratenok e E. V. Shamrikova. "Metrological Aspects of Studying the Granulometric Composition of Soil According to The Method of N.A. Kachinsky". Počvovedenie, n. 7 (19 dicembre 2024): 997–1018. https://doi.org/10.31857/s0032180x24070062.
Testo completoAbstract (sommario):
Based on a significant volume of soil samples of various genesis presented on the territory of the Komi Republic, a study of their granulometric composition (GC) was carried out in accordance with the Kachinsky method (MK). Calculated, procedural, random and systematic factors influencing the precision and correctness of measurement results performed in accordance with the MK prescription are considered. The influence of sample preparation (the degree of grinding of soil samples) and procedures for measuring the mass fraction of elementary soil particles (ESP) on the quality of the results of studying soil GS was assessed. The instability of measuring the mass fraction of fine sand (0.05–0.25 mm) and coarse dust (0.01–0.05 mm) fractions when using the MK recipe was shown. The dependence of the uncertainty of measurement results, caused by random factors, on the mass fraction of ECPs included in the granulometric fractions is noted – the lower the mass fraction of ECPs in the composition of the fractions, the higher the uncertainty of the measurement results. A modification of the Kaczynski method (MMK) has been developed to improve the quality of soil HS assessment results. It includes: (1) separation of fine sand particles using a sieve with a mesh diameter of 0.05 mm (instead of calculating this fraction by difference according to the MK recipe); (2) use of scales of the first class of accuracy to measure the mass fraction of dust and sludge particles; (3) control of the HS research process based on the summation of the measured values of the mass fraction of ESP of six fractions and acid-soluble compounds (losses from HCl treatment). The standard for operational control of the mass fraction of the amount of ECP after dividing them into fractions is (100 ± 5)%. A metrological study of the Kaczynski technique and its modifications was carried out. The proposed modification of Kaczynski’s technique made it possible to reduce the uncertainty in the measurement results of the mass fraction of ECP of small fractions (ωn 10%) and shift the lower limit of measurements to 1%.
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Heagy, William K., e Paul J. Sullivan. "The expected mass fraction". Atmospheric Environment 30, n. 1 (gennaio 1996): 35–47. http://dx.doi.org/10.1016/1352-2310(95)00282-4.
Testo completo
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Vladimir, Kozin, e Komlev Aleksei. "Asymmetric distributions of desired component mass fraction in point samples". Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal 5 (20 ottobre 2022): 77–87. http://dx.doi.org/10.21440/0536-1028-2022-5-77-87.
Testo completoAbstract (sommario):
Introduction. Desired component mass fraction distributions in point samples at preparation plants are asymmetric, and it is due to the natural heterogeneity of ores. The theory of mass fractions distribution asymmetry in samples. The theory is based on the lump sampling of point samples. Mass fraction distributions here consist of two differentsized fractions: valuable mineral and rock. These distributions are always asymmetric. Lump dispersion for asymmetric distributions depends on the mass fraction of the valuable mineral for both released grains and aggregates. Mass fraction distribution in point samples with poor product mass fraction is described by the Poisson formula. Materials and methods of research. Mass fraction distribution correspondence to the Poisson formula was experimentally confirmed based on an artificial rock mass represented by quartz grit with colored markers. Point samples of different mass were collected from the rock mass. Experimental estimates. The distributions obtained experimentally correspond to the distributions calculated by the Poisson formula. The paper introduces a method for experimental determination of valuable mineral average grain size and ore texture index. These values were determined for asbestos ore to exemplify the method proposed. Results discussion. Sampling standards do not consider the asymmetry of mass fraction distributions in point samples. At preparation plants the asymmetry manifests itself in hurricane samples, positive product imbalance, and divergence of double weights analysis results, that exceed the acceptable limits. The asymmetry of components mass fraction distributions in concentrates should be taken into account in sampling standards and methods, as well as at preparation plants in general.
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Frohlich, B., M. Riederer e J. Tautz. "Comb-wax discrimination by honeybees tested with the proboscis extension reflex". Journal of Experimental Biology 203, n. 10 (15 maggio 2000): 1581–87. http://dx.doi.org/10.1242/jeb.203.10.1581.
Testo completoAbstract (sommario):
We used the proboscis extension reflex of honeybees to test their ability to discriminate between comb waxes of different ages (wax scales, 1-week-old wax, 2- to 3-year-old wax, 8- to 10-year-old wax). Such waxes differ in their chemical composition, and an ability to discriminate between them may aid the orientation of the bees in the nest. To train the bees, we used whole extracts of waxes and four different fractions of the whole extract based on different elutions of solid-phase extractions (extract I, fraction A eluted with hexane and fraction B with diethylether; extract II, fraction B further subdivided into fraction C by elution with isopropylchloride and fraction D by elution with diethylether). In a differential training regime (six learning and six test trials) with whole extracts or with the different fractions, we paired one type of wax with a reward and another with no reward. The bees learned to discriminate between all tested pairs of whole extracts. The two subfractions (fractions A and B) gave different results: the bees could discriminate between waxes of different ages when fraction B was used but not when fraction A was used. A further subdivision of fraction B into fractions C and D showed that only fraction D contained the elements that enabled bees to discriminate between old and new wax. Fraction D makes up only 5?8 % of the total wax mass and contains hydroxy alkyl esters (5?6 % of the total wax mass), primary alcohols (0.3?0.5 % of the total wax mass) and acids (0.06?1. 0 % of the total wax mass). Fractions A and C (together forming 62?64 % of the total wax mass), which consist of unbranched and branched aliphatic hydrocarbons and alkyl esters, could not be discriminated by the bees. The remaining wax mass (25?29 %) was eluted with a mixture of chloroform, methanol and water (13:5:1) as fraction E.
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Do, Dinh Nhat, Dinh Phuc Nguyen, Viet-Duc Phung, Xuan-Tien Le, Tuan Minh Le, Van Manh Do, Bui Quang Minh e Xuan Cuong Luu. "Fractionating of Lemongrass (Cymbopogon citratus) Essential Oil by Vacuum Fractional Distillation". Processes 9, n. 4 (29 marzo 2021): 593. http://dx.doi.org/10.3390/pr9040593.
Testo completoAbstract (sommario):
Lemongrass essential oil has many compounds appropriate for application in foods, cosmetics, and pharmaceutical products. Of these, citral is a high-value compound of interest to industry. This work aims to evaluate the use of vacuum fractional distillation to separate lemongrass essential oil compounds, producing essential oil fractions containing high citral content. The effect of process parameters, namely vacuum pressure, type column, and energy input, on the fractionation time, content, and recovery of citral in the fractions, was investigated. The fractionation of lemongrass oils successfully provided five fractions, i.e., fraction 1 (F1), fraction 2 (F2), fraction 3 (F3), fraction 4 (F4), and fraction 5 (F5). GC-MS (Gas Chromatography-Mass Spectrometry) spectra showed that the main compound contained in F1 and F2 fractions was β-myrcene (>70%). Meanwhile, F4 and F5 were the two main fractions for citral recovery. The optimal conditions of the fractional distillation system included a column height of 400 mm, power input of 165 W, and pressure of 15 mmHg. These conditions correspond to the highest total citral content of 95%, with a recovery of 80% at the F4 and F5 fractions. Therefore, fractional vacuum distillation may be an effective method to upgrade lemongrass essential oil.
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Yang, Xingyun, e Karen L. Masters. "How Bar Fraction Depends on Baryon Fraction". Research Notes of the AAS 6, n. 10 (6 ottobre 2022): 206. http://dx.doi.org/10.3847/2515-5172/ac9735.
Testo completoAbstract (sommario):
Abstract We use Galaxy Zoo 2 morphologies (based on SDSS Legacy Imaging) alongside the completed Arecibo Legacy Fast ALFA survey measuring H i to investigate the correlation between bar fraction and an estimate of baryonic mass fraction for a sample of nearby (z < 0.06) disk galaxies (M ⋆ > 109 M ⊙). As expected from theoretical considerations, and as seen in previous work using different samples/morphological classifications, we find clear evidence of an increase in bar fraction, particularly strong bar fraction in galaxies with larger baryonic mass fractions (i.e., heavier discs for their dark matter halo).
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Kumar, Vickal V., Christian Jakob, Alain Protat, Christopher R. Williams e Peter T. May. "Mass-Flux Characteristics of Tropical Cumulus Clouds from Wind Profiler Observations at Darwin, Australia". Journal of the Atmospheric Sciences 72, n. 5 (1 maggio 2015): 1837–55. http://dx.doi.org/10.1175/jas-d-14-0259.1.
Testo completoAbstract (sommario):
Abstract Cumulus parameterizations in weather and climate models frequently apply mass-flux schemes in their description of tropical convection. Mass flux constitutes the product of the fractional area covered by convection in a model grid box and the vertical velocity in cumulus clouds. However, vertical velocities are difficult to observe on GCM scales, making the evaluation of mass-flux schemes difficult. Here, the authors combine high-temporal-resolution observations of in-cloud vertical velocities derived from a pair of wind profilers over two wet seasons at Darwin with physical properties of precipitating clouds [cloud-top heights (CTH), convective–stratiform classification] derived from the Darwin C-band polarimetric radar to provide estimates of cumulus mass flux and its constituents. The length of this dataset allows for investigations of the contributions from different cumulus cloud types—namely, congestus, deep, and overshooting convection—to the overall mass flux and of the influence of large-scale conditions on mass flux. The authors found that mass flux was dominated by updrafts and, in particular, the updraft area fraction, with updraft vertical velocity playing a secondary role. The updraft vertical velocities peaked above 10 km where both the updraft area fractions and air densities were small, resulting in a marginal effect on mass-flux values. Downdraft area fractions are much smaller and velocities are much weaker than those in updrafts. The area fraction responded strongly to changes in midlevel large-scale vertical motion and convective inhibition (CIN). In contrast, changes in the lower-tropospheric relative humidity and convective available potential energy (CAPE) strongly modulate in-cloud vertical velocities but have moderate impacts on area fractions. Although average mass flux is found to increase with increasing CTH, it is the environmental conditions that seem to dictate the magnitude of mass flux produced by convection through a combination of effects on area fraction and velocity.
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Tiven, Nafly Comilo, e Tienni Mariana Simanjorang. "Effect of Substitution of Beef and Broiler Meat with Tuna Meat on Chemical and Sensory Quality of Meatballs". Food Technology and Biotechnology 62, n. 3 (luglio 2024): 314–25. http://dx.doi.org/10.17113/ftb.62.03.24.8278.
Testo completoAbstract (sommario):
Research background. Tuna meat is rich in protein and polyunsaturated fatty acids (PUFA), but low in cholesterol and fat, which makes it an excellent candidate for replacing beef and broiler chicken to produce higher quality meatballs. The aim of this study is to determine how substituting beef and broiler meat with tuna meat affects the chemical and sensory characteristics of meatballs. Experimental approach. In this study, 1000 g of meatballs were prepared from 60 % of beef or broiler chicken. Each meat was replaced with tuna meat at mass fractions of 0, 20 and 40 %. The meat was finely ground and mixed with mass fractions (in %) of: tapioca flour 20, garlic 1.2, salt 2, ground pepper 0.5, egg white 0.3 and ice cubes 16. The tested variables included the chemical quality (moisture, protein, fat, ash, cholesterol and fatty acids) and sensory quality (colour, aroma, elasticity, texture and taste) of the meatballs. The data obtained were statistically analysed using a completely randomised factorial design analysis of variance. Results and conclusions. The results show that increasing the mass fraction of tuna as a substitute for beef and broiler meat significantly increased (p<0.01) the moisture, protein and PUFA mass fractions and colour, but decreased (p<0.01) the cholesterol and fat mass fraction of the meatballs. A significant interaction (p<0.01) was observed between the tuna mass fraction and the type of meat, which affected the mass fractions of moisture, protein, cholesterol and fat as well as colour of the meatballs. In particular, increasing the tuna mass fraction to 40 % significantly increased (p<0.01) the moisture mass fraction of the beef meatballs, as well as the protein mass fraction and colour of the beef and chicken meatballs. However, the moisture mass fraction of chicken meatballs and the fat and cholesterol mass fraction of beef and chicken meatballs decreased significantly (p<0.01). In conclusion, replacing 40 % of beef and chicken meatballs with tuna can improve protein content and colour, and reduce fat and cholesterol content. Novelty and scientific contribution. These results suggest that tuna can be used as a substitute for beef and chicken to produce higher quality meatballs that are rich in protein but low in cholesterol and fat. This approach can also be applied to other processed meat products such as sausages and nuggets to improve their nutritional quality.
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Chamberlain, Katie, Gurtina Besla, Ekta Patel, Vicente Rodriguez-Gomez, Paul Torrey, Garreth Martin, Kelsey Johnson et al. "A Physically Motivated Framework to Compare Pair Fractions of Isolated Low- and High-mass Galaxies across Cosmic Time". Astrophysical Journal 962, n. 2 (1 febbraio 2024): 162. http://dx.doi.org/10.3847/1538-4357/ad19d0.
Testo completoAbstract (sommario):
Abstract Low-mass galaxy pair fractions are understudied, and it is unclear whether low-mass pair fractions evolve in the same way as more massive systems over cosmic time. In the era of JWST, Roman, and Rubin, selecting galaxy pairs in a self-consistent way will be critical to connect observed pair fractions to cosmological merger rates across all mass scales and redshifts. Utilizing the Illustris TNG100 simulation, we create a sample of physically associated low-mass (108 < M * < 5 × 109 M ⊙) and high-mass (5 × 109 < M * < 1011 M ⊙) pairs between z = 0 and 4.2. The low-mass pair fraction increases from z = 0 to 2.5, while the high-mass pair fraction peaks at z = 0 and is constant or slightly decreasing at z > 1. At z = 0 the low-mass major (1:4 mass ratio) pair fraction is 4× lower than high-mass pairs, consistent with findings for cosmological merger rates. We show that separation limits that vary with the mass and redshift of the system, such as scaling by the virial radius of the host halo (r sep < 1R vir), are critical for recovering pair fraction differences between low-mass and high-mass systems. Alternatively, static physical separation limits applied equivalently to all galaxy pairs do not recover the differences between low- and high-mass pair fractions, even up to separations of 300 kpc. Finally, we place isolated mass analogs of Local Group galaxy pairs, i.e., Milky Way (MW)–M31, MW–LMC, LMC–SMC, in a cosmological context, showing that isolated analogs of LMC–SMC-mass pairs and low-separation (<50 kpc) MW–LMC-mass pairs are 2–3× more common at z ≳ 2–3.
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Donovan, John J., Nicholas E. Pingitore e Andrew Westphal. "Compositional Averaging of Backscatter Intensities in Compounds". Microscopy and Microanalysis 9, n. 3 (23 maggio 2003): 202–15. http://dx.doi.org/10.1017/s1431927603030137.
Testo completoAbstract (sommario):
We present high-precision measurements of pure element stable isotope pairs that demonstrate mass has no influence on the backscattering of electrons at typical electron microprobe energies. The traditional prediction of average backscatter intensities in compounds was pragmatically based on elemental mass fractions. Our isotopic measurements establish that this approximation has no physical basis. We propose an alternative model to mass fraction averaging, based on the number of electrons or protons, termed “electron fraction,” which predicts backscatter yield better than mass fraction averaging. We also present an improved backscatter (electron loss) factor based on a modified electron fraction average for the ZAF atomic number correction that provides a significant analytical improvement, especially where large atomic number corrections are required.
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Vogt, J. A., A. J. Fischman, M. Kempf, Y. M. Yu, R. G. Tompkins e J. F. Burke. "A general model for analysis of the tricarboxylic acid cycle with use of [13C]glutamate isotopomer measurements". American Journal of Physiology-Endocrinology and Metabolism 266, n. 6 (1 giugno 1994): E1012—E1022. http://dx.doi.org/10.1152/ajpendo.1994.266.6.e1012.
Testo completoAbstract (sommario):
A generalized steady-state model was developed for determining tricarboxylic acid cycle fractional fluxes from 13C nuclear magnetic resonance (NMR) data. The model relates the measured mole fractions of [13C]glutamate isotopomers to the fractional fluxes and predicted mole fractions of isotopomers of oxaloacetate (OAA) and acetyl-CoA. This model includes cycling between OAA and fumarate. Fractional fluxes are determined by fitting the model equations to NMR parameters by use of nonlinear least squares. Although only fractional fluxes can be determined from 13C-NMR data, when they are combined with mass spectroscopic measurements, absolute values can be derived. A specific metabolic system represented by published 13C-NMR data from extracts of hearts perfused with [13C]acetate, [13C]pyruvate (PYR), and [13C]acetate plus [13C]PYR was used to test the model. The intensities of predicted 13C-NMR splitting patterns were compared with observed values, and there was excellent agreement between observed and predicted signal intensities. With this model, important physiological parameters, including the OAA-derived fraction of inflow to PYR, PYR-derived fraction of inflow to acetyl-CoA, citrate-derived fraction of inflow to OAA, and PYR-derived fraction of inflow to OAA, can be determined.
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Kochemirovsky, Vladimir, Svetlanav Kochemirovskaia, Michael Malygin, Alexey Kuzmin, Maxim Novomlinsky, Alena Fogel e Lev Logunov. "Low-Frequency Magnetic Scanning Device and Algorithm for Determining the Magnetic and Non-Magnetic Fractions of Moving Metallurgical Raw Materials". Applied Sciences 9, n. 10 (16 maggio 2019): 2001. http://dx.doi.org/10.3390/app9102001.
Testo completoAbstract (sommario):
The development of an algorithm to automate the process of measuring the magnetic properties of macroscopic objects in motion is an important problem in various industries, especially in ferrous metallurgy and at factories where ferrous scrap is a strategic raw material. The parameter that requires work control is the hidden mass fraction of a non-magnetic substance that is present in the ferromagnetic raw material. The solution to this problem has no prototypes. In our work, a simple measuring device and a mathematical algorithm for calculating the mass fraction of the non-magnetic fraction in a strongly magnetic matrix were developed. The device is an inductance coil, in which the angle of the electromagnet losses is related to the mass of the magnetic material moving the coil. The magnitude of the instantaneous values of the lost angle integral was compared with the result of weighing the object on scales. This allowed us to calculate the proportion of the magnetic and non-magnetic fractions. The use of this prototype is herein illustrated. The experimental results of the determination of the magnetic-fractional composition depending on the mass of scrap metal and its bulk and the magnetic characteristics are presented.
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Vadasz, Peter. "A Hidden Anomaly in the Binary Mixture Natural Convection Subject to Flux Boundary Conditions". Physics 3, n. 1 (23 marzo 2021): 144–59. http://dx.doi.org/10.3390/physics3010012.
Testo completoAbstract (sommario):
The problem of natural convection in a binary mixture subject to realistic boundary conditions of imposed zero mass flux on the solid walls shows solutions that might lead to unrealistic negative values of the mass fraction (or solute concentration). This anomaly is being investigated in this paper, and a possible way of addressing it is suggested via a mass-fraction-dependent thermodiffusion coefficient that can have negative values in regions of low mass fractions.
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Bihałowicz, Jan Stefan, Artur Badyda, Wioletta Rogula-Kozłowska, Kamila Widziewicz-Rzońca, Patrycja Rogula-Kopiec, Dmytro Chyzhykov, Grzegorz Majewski e Mariusz Pecio. "Particulate Matter During Food Preparation on a Barbecue: A Case Study of an Electric Barbecue". Applied Sciences 15, n. 2 (7 gennaio 2025): 498. https://doi.org/10.3390/app15020498.
Testo completoAbstract (sommario):
The distribution of mass and the number of particles is a determining factor in the respirable nature of a given particulate matter (PM), and thus in the potential health effects of breathing the air in question. One of the most popular activities during the summer months is the preparation of food on a barbecue. Barbecuing represents one of the few sources of combustion particulates during the summer, a period which is otherwise characterised by a lack of heating. The objective of this study is to ascertain the fractional composition of PM emitted during food preparation on an electric barbecue and to compare these values with the measured background. The concentrations of particulate matter (PM) at the barbecue were determined with a Palas AQ Guard optical spectrometer, while the background concentrations were measured with a Palas Fidas 200 optical spectrometer that complies with the EN16450 standard. The contribution of the individual PM fractions measured in the barbecue environment differed from that observed in the ambient air. The background measurements exhibited a relatively well-defined and consistent distribution, with the PM1 fraction representing between 10 and 30% of the PM mass and the PM4−1 fraction accounting for only 10 to 20%. Thus, the mass of the PM4 fraction did not exceed 50% of the total mass of particles. Upon analysis of the particles emitted during the grilling process, it was observed that the PM1 fraction was capable of accounting for a substantial proportion, exceeding 90% of the PM mass. The trend related to the PM4−1 fraction was maintained; however, the limit of the maximum content of this fraction increased to 40% of the PM. The results demonstrate that the barbecue process itself, utilising a barbecue without emission fuel, can exert a notable influence on the contribution of submicron PM.
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Alshevskiy, D. L., R. S. Mavlyudov e M. N. Alshevskaya. "SCIENTIFIC BASIS FOR FORMULATION AND TECHNOLOGICAL PARAMETERS OF STRUCTURED FILLER PREPARED FROM UNDERUSED SQUID FRACTIONS". Bulletin of Kamchatka State Technical University, n. 69 (2024): 8–20. http://dx.doi.org/10.17217/2079-0333-2024-69-8-20.
Testo completoAbstract (sommario):
When developing formulations of structured fillers from various fractions of squid, it is necessary to establish parameters that affect the rheological and organoleptic characteristics of the resulting semi-finished product. The researches of influence of the ratio of the mass fraction of various fractions of squid, the complex food additive KF Stabipro FET, as well as temperature processing conditions on the rheological and organoleptic properties of structured fillers were carried out. The mass fraction of the food additive KF Stabipro FET equal to 4–5%, as well as the mass fraction of crushed mantle, crushed skin, fermented squid skin equal to 20 to 50%, necessary for the production of a structured filler suitable for the further production of semi-finished squid products were established.
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Gómez-Jacinto, Veronica, Ana Arias-Borrego, Tamara García-Barrera, Ines Garbayo, Carlos Vílchez e José Luis Gómez-Ariza. "Iodine speciation in iodine-enriched microalgae Chlorella vulgaris". Pure and Applied Chemistry 82, n. 2 (31 gennaio 2010): 473–81. http://dx.doi.org/10.1351/pac-con-09-08-01.
Testo completoAbstract (sommario):
The characterization of iodine species in the microalgae Chlorella vulgaris after cultivation with different potassium iodide concentrations was performed using the coupling of multidimensional chromatography (size exclusion chromatography, SEC, and anion exchange chromatography, AEC) with inductively coupled plasma-mass spectrometry (ICP-MS) detection. Two iodine fractions, water-soluble and macromolecular fractions, were obtained using a sequential extraction scheme based on chemical reagents. Most iodine species separated from the water-soluble fraction with SEC-ICP-MS (mass range from 0.5 to 100 kDa) are present in inorganic forms (peak III), although the other two peaks were detected (peaks I and II). The application of AEC to the isolated peak III fraction allows the characterization of IO3– (about 25 %) and I– (about 75 %). The application of SEC-ICP-MS (mass range from 10 to 1200 kDa) to the macromolecular fraction reveals the presence of four peaks from the void volume to about 67 kDa, a peak is located about 600 kDa. The mass balance of iodine in the different fractions obtained from the microalgae raw stuff shows that the water-soluble fraction represents 66.7 % of total iodine in microalgae, but the macromolecular fraction only contains 13.3 %, both summing up for 79.9 % of the total amount of iodine, which confirms the suitability of the separation scheme. Further studies have to be focused on the purification of the isolated fractions and their identification by tandem MS.
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Courteau, Stéphane, e Aaron A. Dutton. "The Mass Distribution in Disk Galaxies". Proceedings of the International Astronomical Union 11, A29B (agosto 2015): 195–96. http://dx.doi.org/10.1017/s1743921316004865.
Testo completoAbstract (sommario):
AbstractWe present the relative fraction of baryons and dark matter at various radii in galaxies. For spiral galaxies, this fraction measured in a galaxy's inner parts is typically baryon-dominated (maximal) and dark-matter dominated (sub-maximal) in the outskirts. The transition from maximal to sub-maximal baryons occurs within the inner parts of low-mass disk galaxies (with Vtot ≤ 200 km s−1) and in the outer disk for more massive systems. The mean mass fractions for late- and early-type galaxies vary significantly at the same fiducial radius and circular velocity, suggesting a range of galaxy formation mechanisms. A more detailed discussion, and resolution of the so-called “maximal disk problem”, is presented in Courteau & Dutton, ApJL, 801, 20.
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Denis, Marie-Claude, Pascal Dubé, Stéphanie Dudonné, Yves Desjardins, Cristina Matei, Edgard Delvin, Emile Levy e Alexandra Furtos. "Characterization of bioactive cranberry fractions by mass spectrometry". Canadian Journal of Chemistry 98, n. 9 (settembre 2020): 589–96. http://dx.doi.org/10.1139/cjc-2020-0070.
Testo completoAbstract (sommario):
Increasing evidence indicates that fruits contain functional bio-active compounds that have several preventive and therapeutic health benefits. Our group has recently conducted studies to assess the potential effects of cranberry polyphenolic fractions on intestinal Caco-2/15 epithelial cells and a substantial reduction in oxidative stress and inflammation was observed. The aim of the present work was to determine the polyphenolic species most likely responsible for the observed biological activity. Low, medium, and high molecular weight cranberry fractions were generated with a Sephadex LH-20 column by elution with 60% MeOH, 100% MeOH, and 70% acetone, respectively. The total phenolic content in these fractions was determined by the Folin–Ciocalteu method. A combination of LC–MS and MALDI-TOF methods were used to characterize the nature of polyphenolic compounds in the cranberry extracts. High resolution mass spectrometry was used to generate empirical formulae for the detected species. The low molecular weight fraction was essentially constituted of small phenolic acids (hydroxycinnamic and hydroxybenzoic acids). The medium fraction was mostly composed of anthocyanin, flavonols (quercetin, myricetin, isorhamnetin, kaempferol), procyanidins monomers (epicatechin, catechin), dimers, and few small oligomers. The heavy fraction was devoid of phenolic acids and anthocyanins, and it contained for the most part oligomers and polymers of procyanidins. Proanthocyanidins oligomers up to n = 22 were detected, which is, to our knowledge, the largest individual polymers reported to date. With this approach, it was also possible to distinguish between the A-type and B-type linkages.
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Fang, Yiran, Xiaojun Zou, Zhiyang Lie e Li Xue. "Variation in Organ Biomass with Changing Climate and Forest Characteristics across Chinese Forests". Forests 9, n. 9 (29 agosto 2018): 521. http://dx.doi.org/10.3390/f9090521.
Testo completoAbstract (sommario):
Forest biomass allocation patterns are important for understanding global carbon cycling and climate change, which might change with environmental conditions and forest characteristics. However, the effects of climate and forest characteristics on biomass allocation fractions (the fraction of total forest biomass distributed in organs) remains unknown. The authors use a large Chinese biomass dataset (1081 forests encompassing 10 forest types) to analyse the responses of biomass allocation fractions to biogeography, climate, and forest characteristics. The authors found that the stem mass fraction significantly increased with age and precipitation and significantly decreased with latitude and temperature. The branch mass fraction significantly decreased with age and density, but significantly increased with temperature and latitude. The leaf mass fraction significantly decreased with age and precipitation and significantly increased with temperature. The root mass fraction significantly increased with latitude and density, and significantly decreased with precipitation. The results suggest that latitude, temperature, precipitation, stand age and density are good predictors of biomass partitioning. These findings support the hypotheses that variation in resource availability constrains organ allocation and provides biogeographically explicit relationships between biomass allocation and both environmental and forest characteristics, which might be used for assessing the impact of changing environmental and forest characteristics on forest carbon dynamics and fixation.
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LIU, Zhaolin, Yang YANG, Yuwen WANG, Xuehui GAN e Ni WANG. "Preparation and Properties of Opaque Polyethylene Terephthalate/TiO2 Filaments". Materials Science 27, n. 3 (23 agosto 2021): 325–29. http://dx.doi.org/10.5755/j02.ms.24524.
Testo completoAbstract (sommario):
The opaque polyethylene terephthalate (PET) filaments with different mass fractions of TiO2 particles were prepared by low-speed melt spinning and drafting. Basic structures including surface morphology, linear density, orientation degree and crystallinity, and properties including tensile and optical property of the PET/TiO2 filaments were systematically analyzed, especially the visual shielding property. The results showed that TiO2 particles were well-distributed on the filament surface without obvious aggregation, except when the mass fraction of TiO2 exceeded 6%. The addition of TiO2 increased the linear density of the PET filaments. The orientation degree of the filaments was positively correlated with the drafting ratio but hardly influenced by the mass fraction of TiO2. The crystallinity achieved the maximum when the mass fraction of TiO2 was 3% and then decreased gradually. The tenacity of the filaments reduced and the elongation at break enhanced initially and then decreased with the increasing TiO2 content. The opaque effect of the PET filaments improved significantly when the mass fraction of TiO2 was less than 6%, whereas the improvement of the opaque effect slowed down as the mass fraction of TiO2 increased further.
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Davison, Thomas A., Mark A. Norris, Joel L. Pfeffer, Jonathan J. Davies e Robert A. Crain. "An EAGLE’s view of ex situ galaxy growth". Monthly Notices of the Royal Astronomical Society 497, n. 1 (24 giugno 2020): 81–93. http://dx.doi.org/10.1093/mnras/staa1816.
Testo completoAbstract (sommario):
ABSTRACT Modern observational and analytical techniques now enable the direct measurement of star formation histories and the inference of galaxy assembly histories. However, current theoretical predictions of assembly are not ideally suited for direct comparison with such observational data. We therefore extend the work of prior examinations of the contribution of ex situ stars to the stellar mass budget of simulated galaxies. Our predictions are specifically tailored for direct testing with a new generation of observational techniques by calculating ex situ fractions as functions of galaxy mass and morphological type, for a range of surface brightnesses. These enable comparison with results from large field of view (FoV) Integral Field Unit (IFU) spectrographs, and increasingly accurate spectral fitting, providing a look-up method for the estimated accreted fraction. We furthermore provide predictions of ex situ mass fractions as functions of galaxy mass, galactocentric radius, and environment. Using z = 0 snapshots from the 100 and 25 cMpc3 EAGLE (Evolution and Assembly of GaLaxies and their Environments) simulations, we corroborate the findings of prior studies, finding that ex situ fraction increases with stellar mass for central and satellite galaxies in a stellar mass range of 2 × 107 to 1.9 × 1012 M⊙. For those galaxies of mass M* > 5 × 108 M⊙, we find that the total ex situ mass fraction is greater for more extended galaxies at fixed mass. When categorizing satellite galaxies by their parent group/cluster halo mass, we find that the ex situ fraction decreases with increasing parent halo mass at fixed galaxy mass. This apparently counterintuitive result may be due to high passing velocities within large cluster haloes inhibiting efficient accretion on to individual galaxies.
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Tvorogova, A. A., T. V. Shobanova, I. A. Gurskiy e N. V. Kazakova. "The quality indicators of ice cream upon the enzymatic hydrolysis of lactose". Food systems 6, n. 3 (12 ottobre 2023): 308–16. http://dx.doi.org/10.21323/2618-9771-2023-6-3-308-316.
Testo completoAbstract (sommario):
Ice cream is a popular type of dairy foods containing up to 6% of lactose. In connection with the lactose intolerance by many consumers and the possibility of its crystallization during storage of finished products, there is a need for a decrease in the content of this nutrient in the composition of ice cream. The aim of the research was to study an effect of the lactose hydrolysis process in ice cream with the fat mass fraction of 15% and different mass fractions of dry skim milk residue on technologically significant and sensory properties of its quality. The main objects of the study were samples of ice cream subjected to lactose hydrolysis at the stage of mixture maturation. The fat mass fraction in the samples was 15%, mass fractions of dry skim milk residue were 7, 10, 12 and 15%. The composition of sugars was determined by high-performance liquid chromatography, the dynamic viscosity of mixes and the consistency of ice cream by rheological methods and the dispersion of structural elements by microcopy. The effects of the mass fraction of dry skim milk residue and lactose hydrolysis on quality indicators of mixtures and ice cream were determined. As the mass fraction of dry skim milk residue rose from 7 to 15%, the residual content of lactose increased from 0.2 to 1.1%, while the dynamic viscosity of the mixture increased by 1.3 times. A decrease in the freezing point by 0.6–0.8 °C and an increase in melting resistance were also observed. The mass fraction of melt after 2 hours of holding decreased to 4.7–0.7%. Also, indicators of consistency (hardness, adhesiveness, adhesion force and rigidity) decreased by 1.1–1.7 times (upon a mass fraction of dry skim milk residue of 7 and 10%). The samples of ice cream subjected to lactose hydrolysis were characterized by a high dispersion of structural elements typical for a traditional product, and by improved texture and increased sensation of sweetness. The complex of investigations to study quality indicators of ice cream with the fat mass fraction of 15% showed that a change in the mass fraction of dry skim milk residue upon enzymatic hydrolysis of lactose results in formation of different structural-mechanical and sensory indicators that should be considered during the creation of assortment and development of formulations of low-lactose products.
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Mani, Janice, Joel Johnson, Holly Hosking, Luke Schmidt, Ryan Batley, Ryan du Preez, Daniel Broszczak, Kerry Walsh, Paul Neilsen e Mani Naiker. "Bioassay-Guided Fractionation of Pittosporum angustifolium and Terminalia ferdinandiana with Liquid Chromatography Mass Spectroscopy and Gas Chromatography Mass Spectroscopy Exploratory Study". Plants 13, n. 6 (12 marzo 2024): 807. http://dx.doi.org/10.3390/plants13060807.
Testo completoAbstract (sommario):
Bioprospecting native Australian plants offers the potential discovery of latent and novel bioactive compounds. The promising cytotoxic and antibacterial activity of methanolic extracts of Pittosporum angustifolium and Terminalia ferdinandiana led to further fractionation and isolation using our laboratory’s bioassay-guided fractionation protocol. Hence, the aim of this study was to further evaluate the bioactivity of the fractions and subfractions and characterize bioactive compounds using liquid chromatography mass spectroscopy (LC-MS/MS) and gas chromatography MS (GC-MS). Compounds tentatively identified in P. angustifolium Fraction 1 using LC-ESI-QTOF-MS/MS were chlorogenic acid and/or neochlorogenic acid, bergapten, berberine, 8′-epitanegool and rosmarinic acid. GC-MS analysis data showed the presence of around 100 compounds, mainly comprising carboxylic acids, sugars, sugar alcohols, amino acids and monoalkylglycerols. Furthermore, the fractions obtained from T. ferdinandiana flesh extracts showed no cytotoxicity, except against HT29 cell lines, and only Fraction 2 exhibited some antibacterial activity. The reduced bioactivity observed in the T. ferdinandiana fractions could be attributed to the potential loss of synergy as compounds become separated within the fractions. As a result, the further fractionation and separation of compounds in these samples was not pursued. However, additional dose-dependent studies are warranted to validate the bioactivity of T. ferdinandiana flesh fractions, particularly since this is an understudied species. Moreover, LC-MS/GC-MS studies confirm the presence of bioactive compounds in P. angustifolium Fraction 1/subfractions, which helps to explain the significant acute anticancer activity of this plant. The screening process designed in this study has the potential to pave the way for developing scientifically validated phytochemical/bioactivity information on ethnomedicinal plants, thereby facilitating further bioprospecting efforts and supporting the discovery of novel drugs in modern medicine.
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Jones, Dryw, e Kevin O’Hara. "Variation in Carbon Fraction, Density, and Carbon Density in Conifer Tree Tissues". Forests 9, n. 7 (18 luglio 2018): 430. http://dx.doi.org/10.3390/f9070430.
Testo completoAbstract (sommario):
We analyzed variations in three tree properties: tissue density, carbon fraction, and carbon density within bole tissues of nine Californian conifer species. Model performance for all three tree properties was significantly improved with the addition of covariates related to crown characteristics and position within the tree. This suggests that biomass and carbon mass estimates that rely on fixed wood density and carbon fraction may be inaccurate across tree sizes. We found a significant negative relationship between tissue density and carbon fraction within tree bole tissues, indicating that multiplying biomass by an average carbon fraction to obtain carbon mass is likely to lead to inaccurate estimates. Measured carbon fractions in tree tissues deviated from the widely used 0.5 value from a low of 1.4% to a high of 17.6%. Carbon fraction model parameters indicate the potential for an additional deviation from this 0.5 value of up to 2.7% due to the interaction between relative height and wood density. Applying measured carbon fractions to whole bole biomasses resulted in carbon mass estimates as much as 10.6% greater than estimates derived using the 0.5 value. We also found a significant, though modest, improvement in carbon fraction model estimates by assigning trees to groups based on tree bark characteristics.
25
Li, Lin, Wei Wang, Yu Wang, Dongxu Li e Mei-Ling Zhuang. "Experimental study on pore structure characteristics and thermal conductivity of fibers reinforced foamed concrete". PLOS ONE 18, n. 7 (7 luglio 2023): e0287690. http://dx.doi.org/10.1371/journal.pone.0287690.
Testo completoAbstract (sommario):
The pore structure characteristics and thermal conductivity of foamed concrete (FC) reinforced with glass fibers (GF), polyvinyl alcohol fibers (PVAF) and polypropylene fibers (PPF) were investigated experimentally in this article. Firstly, GF, PVAF or PPF with different mass fractions (0%, 1%, 1.5% and 2%) were added to the Portland cement, fly ash and plant protein foaming agent to prepare the FC. Then, SEM tests, dry density tests, porosity tests, and thermal conductivity tests were carried out on FRFC. Later, the adhesion of GF, PVAF and FFF with different mass fractions to the cementitious base was investigated by SEM images of FRFC. The pore size distribution, shape factor and porosity of FRFC were analyzed using Photoshop software and Image Pro Plus (IPP) software. Finally, the effects of different mass fractions and lengths of three types of fibers on the thermal conductivity of FRFC were discussed. The results indicated that proper fiber mass fraction can play a role of refining small pores and separating large pores, improving the structural compactness, reducing the pore collapse phenomenon and optimizing the pore structure of FRFC. The three types of fibers can promote the optimization of cellular roundness and increase the proportion of pores with diameters below 400 μm. The FC with larger porosity had smaller dry density. As the fiber mass fraction increased, the thermal conductivity performed a phenomenon of first decrease and then increase. The three types of fibers with 1% mass fraction achieved relatively low thermal conductivity. Compared with the FC without fibers, the thermal conductivities of GF reinforced FC, PVAF reinforced FC and PPF reinforced FC with 1% mass fraction were decreased by 20.73%, 18.23% and 7.00%, respectively.
26
Long, Yue, Zhengzheng Wang, Yaran Cao, Peipei Du e Bo Xu. "Influence of C28H58 on the structure and phase change of C28H58/C22H46 n-alkane mixtures". AIP Advances 13, n. 3 (1 marzo 2023): 035136. http://dx.doi.org/10.1063/5.0141506.
Testo completoAbstract (sommario):
This study adopted molecular dynamics to investigate the influence of C28H58 mass fraction on the structure and phase change of C28H58/C22H46 n-alkane mixtures at different temperatures; systematically analyzed the C–H and C–C bond lengths, changes in the H–C–H bond angle and C–C–C–C torsion angle, and energy conversions within the mixture during heating of C28H58/C22H46 n-alkane mixtures; calculated the self-diffusion coefficient ( D) by combining the Einstein relation and mean squared displacement; and determined the phase change temperature of each mixture according to the relationship between D and temperature. The results show that, at 280 K, changing the mass fraction of C28H58 does not affect the C–H and C–C bond lengths and the H–C–H bond angle. At 350 K, the C–H bond length decreases with the increase in the mass fraction of C28H58, the C–C bond length increases slightly when the mass fraction is 65.2% and remains unchanged for other mass fractions, and the H–C–H bond angle slightly decreases. With an increase in temperature, the peak intensity of the stretched conformation at ±180° gradually decreases, while the peak of the twisted conformation appears around ±70°, and the degree of twist of the C–C–C–C dihedral angle in the mixture increases. The phase change temperature begins to increase slowly with the increase in the mass fraction of C28H58, and the phase change temperature increases rapidly when the mass fraction exceeds 65.2%. The kinetic and potential energies of the mixture tend to increase with the increasing mass fraction of C28H58.
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Dağıdır, Kayhan, e Kemal Bilen. "Experimental investigation of usage of POE lubricants with Al2O3, graphene or CNT nanoparticles in a refrigeration compressor". Beilstein Journal of Nanotechnology 14 (2 novembre 2023): 1041–58. http://dx.doi.org/10.3762/bjnano.14.86.
Testo completoAbstract (sommario):
In this study, the use of nanolubricants containing Al2O3, graphene, and carbon nanotubes (CNTs) at different mass fractions in a refrigeration compressor was experimentally investigated. The required electrical power of the compressor was measured to determine the effect of the use of nanolubricants. Nanoparticles used in the preparation of nanolubricants were gradually added to the lubricant to determine the optimum nanoparticle mass fraction for each nanoparticle type. Thus, it was found that the compressor operated safely and efficiently with nanolubricants. Furthermore, the optimum mass fractions were determined to be 0.750% for Al2O3, 0.250% for graphene, and 0.250% for CNTs for operating conditions of this study. As a result, the required electrical power of the compressor decreased by 6.26, 6.82, and 5.55% with the addition of Al2O3, graphene, and CNT nanoparticles at optimum mass fractions of 0.750, 0.250, and 0.250% to the lubricant, respectively, compared to the compressor using pure oil. Moreover, density and dynamic viscosity of the nanolubricant samples used in the experiments were also measured, and their kinematic viscosity, which is an important parameter for lubricants, was calculated. It was determined that the kinematic viscosity continuously increased with increasing nanoparticle fraction. In conclusion, nanolubricants containing nanoparticles above the optimum mass fraction increase the required electrical power of the compressor. It is concluded that nanoparticle fractions should not be used above the optimum value in nanolubricant applications.
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Yan, Xiaoxing, e Wenwen Peng. "Effect of Microcapsules of a Waterborne Core Material on the Properties of a Waterborne Primer Coating on a Wooden Surface". Coatings 11, n. 6 (30 maggio 2021): 657. http://dx.doi.org/10.3390/coatings11060657.
Testo completoAbstract (sommario):
Microcapsules of a waterborne core material were prepared using a waterborne primer. The microcapsules of the waterborne core material were added to the waterborne primer to explore the effects of different core–shell ratios and mass fractions of the microcapsules on the property of the waterborne primer coating on the wooden surface. The results show that as the mass fraction of the microcapsules increased, the chromatic aberration increased by degrees, the glossiness decreased gradually, and the hardness increased by degrees, whilst—except for the coating with 0.50:1 microcapsules—the adhesion decreased gradually. When the mass fraction of the microcapsules increased, the impact resistance increased first and decreased later, or remained unchanged after reaching a certain value. When the mass fraction of the microcapsules increased, the elongation at the break increased first and decreased later. When the core–shell ratio was small and the mass fraction was between 5.0% and 15.0%, the coating had better liquid resistance. When the core–shell ratio was 0.67:1 and the mass fraction was 10.0%, the overall property of the coating on the Basswood was the best. The technology of microencapsulation provides a technical reference for the waterborne primer with self-repair qualities on the surface of wooden products.
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Tang, Yongzhe, Peng Zhang, Mingxiao Zhu, Jiacai Li, Yuxia Li, Ziguo Wang e Liangsong Huang. "Temperature Effects on the Dielectric Properties and Breakdown Performance of h-BN/Epoxy Composites". Materials 12, n. 24 (9 dicembre 2019): 4112. http://dx.doi.org/10.3390/ma12244112.
Testo completoAbstract (sommario):
Epoxy–boron nitride composites are promising insulating materials, and it is highly important to understand their insulating performances at different temperatures with different nano-doping amounts. In this study, we investigated the effects of different mass fractions of epoxy–micron hexagonal boron nitride composites on their thermal conductivity, as well as the effects of temperature and mass fraction on their insulating performances. The results demonstrated that the thermal conductivity of epoxy–micron hexagonal boron nitride composites was superior to that of neat epoxy. The thermal conductivity of epoxy–micron hexagonal boron nitride composites increased with the mass fraction of hexagonal boron nitride, and their dielectric constant and dielectric loss increased with temperature. The dielectric constant of epoxy–micron hexagonal boron nitride composites decreased as the mass fraction of hexagonal boron nitride increased, while their dielectric losses decreased and then increased as the mass fraction of hexagonal boron nitride increased. Due to internal heat accumulation, the alternating current breakdown strength of epoxy–micron hexagonal boron nitride composites increased and then decreased as the mass fraction of hexagonal boron nitride increased. Additionally, as the temperature increased, the composites transitioned from the glassy state to the rubbery or viscous state, and the breakdown strength significantly degraded.
30
Ye, Wenlian, Yang Liu, Lulu Hu, Peng Yang e Yingwen Liu. "Effect of mixed refrigerant composition on performance of an auto-cascade refrigeration system using R600a/R1150/R14". Thermal Science, n. 00 (2024): 136. http://dx.doi.org/10.2298/tsci240123136y.
Testo completoAbstract (sommario):
A mathematical model based on energy and exergy methods is established to analyze the performance of an auto-cascade refrigeration system at varying compositions of the mixed refrigerants, condensation temperature, evaporation temperature, and vapor quality at the condenser outlet. Furthermore, grey correlation theory is employed to assess the correlation degrees between refrigerant mass fractions and system performance, enabling the identification of the state that has the greatest impact on the output parameters. It has been concluded that while maintaining a constant mass fraction of R600a, an increase in the mass fraction of R1150 (state 1) leads to a higher cooling capacity but a decrease in exergy efficiency. The performance decreases with the increase of the R600a mass fraction (state 2) as the R1150 mass fraction is unchanged. When the component of R14 is constant while the other two components R600a/R1150 vary (state 3), and the COP exists as the optimal value. The mixture of R600a/R1150/R14 with a mass fraction of 0.5:0.2:0.3 has better performance at COP of 0.5027 and exergy efficiency of 29.43 % under a condensation temperature of 30?. Based on the results of the grey correlation degree, the greatest factor in cooling capacity is state 1, while the COP and exergy efficiency are primarily controlled by state 3.
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Krivoy, N., H. Schlüter, M. Karas e W. Zidek. "Generation of angiotensin II from human plasma by tissue kallikrein". Clinical Science 83, n. 4 (1 ottobre 1992): 477–82. http://dx.doi.org/10.1042/cs0830477.
Testo completoAbstract (sommario):
1. Human plasma was incubated with tissue kallikrein from porcine pancreas, dialysed to obtain a fraction with a molecular mass < 10 kDa and further purified by reverse-phase chromatography. 2. Vasopressor activity in the fractions obtained was tested in the isolated perfused rat kidney. 3. In one fraction a strong vasopressor action was found, which was blocked by saralasin and by an angiotensin II antibody. 4. Aprotinin inhibited the formation of vasopressor substances by tissue kallikrein. 5. U.v.-laser desorption/ionization mass spectrometry revealed a molecular mass of 1046 Da in the purified active fraction. 6. It is concluded that tissue kallikrein forms not only kinins, but also angiotensin II, from human plasma under physiological conditions.
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Wei, Li, e Kong Dejun. "Effect of Y2O3 mass fraction on electrochemical corrosion performances of laser cladded CrNi coatings in 3.5% NaCl solution". Anti-Corrosion Methods and Materials 69, n. 2 (2 febbraio 2022): 171–76. http://dx.doi.org/10.1108/acmm-11-2021-2568.
Testo completoAbstract (sommario):
Purpose The purpose of this study is to investigate the effect of Y2O3 mass fraction on the electrochemical corrosion performance of CrNi coating, which provided a foundation for the performance optimization of CrNi coatings. Design/methodology/approach CrNi coatings with the different Y2O3 mass fractions were fabricated on AISI H13 steel by laser cladding, and the effect of Y2O3 mass fraction on the electrochemical performance of CrNi coating in 3.5% NaCl solution was investigated using an electrochemical workstation. Findings The electrochemical corrosion performance of CrNi coating enhances with the increase of Y2O3 mass fraction, and the CrNi–15%Y2O3 coating has the largest polarization resistance and the lowest corrosion current density, which displays the best electrochemical performance among the CrNi–5%Y2O3, –10%Y2O3 and –15%Y2O3 coatings. The protective films are formed with the increase of Y2O3 mass fraction, which inhibits the occurrence of electrochemical corrosion. Originality/value The Y2O3 was first added to the CrNi coating to improve its electrochemical corrosion performance, and the influence of Y2O3 on the corrosion resistance of the CrNi coating was discussed by the corrosion model.
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Perrin, Louise, Sylvie Desobry-Banon, Guillaume Gillet e Stephane Desobry. "Phase Diagram of Pickering Emulsions Stabilized by Cellulose Nanocrystals". Polymers 15, n. 13 (22 giugno 2023): 2783. http://dx.doi.org/10.3390/polym15132783.
Testo completoAbstract (sommario):
Cellulose is a promising renewable and biocompatible biopolymer for stabilizing Pickering emulsions (PEs). In the present study, PEs were produced by low-frequency ultrasounds with cellulose nanocrystals (CNCs) and caprylic/capric triglycerides. Phase diagrams allowed to understand mechanisms of formation and long-term stabilization of PEs. Emulsion type, continuous phase viscosity, and yield of oil incorporation were studied after PEs formation. Droplet size, oil release, and stability were measured weekly up to 56 days of storage. Results showed that oil mass fraction above 70% w/w led to unstable W/O PEs. Lower oil mass fraction formed O/W PEs of stability depending on CNC content and oil mass fraction. Droplet size stability increased with CNCs/oil ratio. A very low CNCs/oil ratio led to phase separation and oil release. High CNC content stabilized oil droplets surface, increased aqueous phase viscosity, and prevented creaming. Highly stable PEs were produced for CNC content above 3% (w/w) and oil mass fraction below 50% (w/w). Mechanisms for PEs formation and stabilization were proposed for various CNC contents and oil mass fractions.
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Sun, Li, Geng Wang, Chunwei Zhang, Qiao Jin e Yansheng Song. "On the rheological properties of multi-walled carbon nano-polyvinylpyrrolidone/silicon-based shear thickening fluid". Nanotechnology Reviews 10, n. 1 (1 gennaio 2021): 1339–48. http://dx.doi.org/10.1515/ntrev-2021-0087.
Testo completoAbstract (sommario):
Abstract This study examines the rheological properties of shear thickening fluid (STF) enhanced by additives such as multi-walled carbon nanotubes (MWCNTs), polyvinylpyrrolidone (PVP), and nano-silica (SiO2) at different mass fraction ratios. The rheological properties of the liquid (MWCNTs–PVP/SiO2–STF) and the effect of the rheological properties of the STF under different plate spacing of the rheometer were investigated. The optimal mass fraction mixing ratio was also studied. The MWCNTs–PVP/SiO2–STF system with different PVP mass fractions was fabricated using ultrasonic technology and the mechanical stirring method. Then, the steady-state rheological test of the MWCNTs–PVP/SiO2–STF system was carried out with the aid of the rheometer facility. Dynamic rheological and temperature sensitivity tests on the MWCNTs–PVP/SiO2–STF system with 0.1 and 0.15% PVP mass fractions were performed. The rheological test results show that the MWCNTs–PVP/SiO2–STF system has a significant shear thickening effect when the PVP mass fraction is increased from 0 to 0.15%. When the PVP mass fraction is 0.1% and the plate spacing is 1 mm, the system exhibits the best shear thickening performance. This is based on the following facts: the viscosity can be achieved as 216.75 Pa s; the maximum energy storage and energy consumption capabilities can be observed. As a result, PVP can significantly enhance the shear thickening performance of the MWCNTs/SiO2–STF system.
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Su, Xuefeng, e Theodore J. Heindel. "Effect of Perforated Plate Open Area on Gas Holdup in Rayon Fiber Suspensions". Journal of Fluids Engineering 127, n. 4 (14 aprile 2005): 816–23. http://dx.doi.org/10.1115/1.1994878.
Testo completoAbstract (sommario):
Three different aeration plates are used to study their effect on gas holdup and flow regime transition in fiber suspensions. The aeration plates differ by their open-area ratios (A=0.57%, 0.99%, and 2.14%), where the hole diameter remains the same while the number of holes increase. Experiments are performed using three different Rayon fiber lengths (L=3, 6, and 12mm) over a range of superficial gas velocities (Ug⩽18cm∕s) and fiber mass fractions (0⩽C⩽1.8%) in a 15.24cm dia semi-batch bubble column. Experimental results show that the aeration plate with A=0.99% produces the highest gas holdup in an air-water system and low fiber mass fraction suspensions, and the plate with A=2.14% yields the lowest gas holdup in these systems. In medium fiber mass fraction suspensions, the plate with A=0.57% produces slightly higher gas holdup values, while the other two plates yield similar results. The effect of the aeration plate open area on gas holdup diminishes at high fiber mass fractions (C⩾1.2%). All aeration plates generate homogeneous, transitional, and heterogeneous flow regimes over the range of superficial gas velocities for air-water and low fiber mass fraction suspensions. However, the aeration plate with A=2.14% enhances the flow regime transition, i.e., the superficial gas velocity at which transitional flow appears is lower. Additionally, the fiber mass fraction at which pure heterogeneous flow is observed is lower when A=2.14%.
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Zueva, N. V., S. A. Veretennikov e I. V. Novikova. "Conversion of by-products of alcohol production to produce isobutanol". Proceedings of the Voronezh State University of Engineering Technologies 84, n. 4 (7 dicembre 2022): 76–79. http://dx.doi.org/10.20914/2310-1202-2022-4-76-79.
Testo completoAbstract (sommario):
Intensive research is underway in all developed countries to create an economical process for the production of butanol and its derivatives from biomass, which reduces the cost of the product compared to existing processes for producing synthetic butanol based on fossil raw materials. This is primarily due to the prospects of using butanol and its derivatives as an alternative fuel. The paper proposes a technology for the production of isobutyl alcohol, which provides for the processing of by-products of alcohol production by hydrogenation of crotonaldehyde. A concentrate of ethyl alcohol head fractions (KGF) and a concentrate of ethyl alcohol head fractions (KGF) were used as objects of research. In the process of work, a technology for processing by-products of alcohol production is proposed, which includes a number of stages with the production of isobutyl alcohol as a finished product, which can be used in the production of plastics, rubber, coatings, medicine and the production of special solvents, as well as as an additive to fuel. Experimental studies were conducted to obtain isobutanol and study its physicochemical properties: color, density; mass fraction of isobutyl alcohol, mass fraction of acids in terms of acetic acid, bromine number, mass fraction of carbonyl compounds in terms of oil aldehyde, mass fraction of non-volatile residue. The technological process at the isobutanol production plant is differentiated by stages, which are carried out sequentially in separate reactors with the treatment of intermediates with catalysts. As a result of the developed technology, butyl alcohol with a mass fraction of isobutyl alcohol of at least 99.3% was obtained.
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Feng, Nianjie, Shaowen She, Chuanqin Hu e Qian Wu. "Liquid Chromatography-Mass Spectrometry Characterized Hydrolysate Fractions Possess Anticancer Activity In Vitro". Journal of Biobased Materials and Bioenergy 16, n. 1 (1 febbraio 2022): 117–26. http://dx.doi.org/10.1166/jbmb.2022.2151.
Testo completoAbstract (sommario):
To find new plant-derived antitumor drugs, hydrolysate and fractions of poplar were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for their inhibitory effect against liver cancer HepG-2 cells. Strong cytotoxicity of hydrolysate was revealed at processing temperature of 180 °C or above. The hydrolysate formed at 180 °C was sequentially extracted using organic solvent to obtain five fractions, and only the diethyl ether-soluble fraction (FDe) showed specific cytotoxicity. The eluted fraction of acetone/n-hexane (F1) was further isolated by column chromatography separation from the FDe fraction at a yield of 70%, and could severely decrease cell viability. LC-MS chromatography indicated that 5-hydroxymethyl furfural, ρ-hydroxybenzoic acid and syringaldehyde were the main compounds in the F1 fraction. Furthermore, the results of flow cytometry, Western blotting, and polymerase chain reaction indicated that syringaldehyde could tightly control the growth and metabolism of HepG-2 cells. The findings could move forward the value-added applications of lignocellulosic hydrolysate on traditional medicines.
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Vakhnina, O. V., I. A. Konopkina, L. N. Kryazhimskaya, N. V. Gerasimova, S. A. Annikova, N. V. Taturina e K. B. Zhogova. "Simultaneous determination of chlorides, bromides, and fluorides in ion-conducting electrolyte". Industrial laboratory. Diagnostics of materials 90, n. 10 (22 ottobre 2024): 24–31. http://dx.doi.org/10.26896/1028-6861-2024-90-10-24-31.
Testo completoAbstract (sommario):
There are developed the techniques of determining the content of chlorides, bromides and fluorides at their joint presence in two types of solid electrolytes differing in matrix content: the first type contains lithium, the second one — both lithium and aluminium, simultaneously. Determination of bromides mass fraction is fulfilled using a method of iodometric titration of iodic potassium excess after bromides are oxidized until free bromine. The fluorides mass fraction is measured by the gravimetric method in the form of fluoro-chloride of lead, in this case the aluminium interfering influence is eliminated by its precipitation in the form of hydroxide after it is fused with carbonates of potassium and natrium, as well as by the method of potentiometric titration with a fluoride ion-selective electrode using the nitrate lanthanum solution. The absence of aluminium interfering influence on the result of fluorine determination is estimated by the «input – found» method. The mass fraction of chlorides is determined by calculation by difference between results of determining the sum of chlorides and bromides using the method of mercurometric titration and — separately — the bromides mass fraction. Optimal conditions of samples preparation and analysis for each of mentioned methods of analysis were selected. The limits of the relative total error of determining bromides in the range of mass fractions from 28.0 to 41.0% is ±2.1%, chlorides within the mass fraction range from 8.0 to 15.0% — ±3.6%, fluorides within the mass fraction range from 3.0 to 7.0% — ±3.4% using gravimetric method and within the mass fraction range from 5.0 to 8.0% — ±1.5% using a method of potentiometric titration. The developed techniques were certified by a metrological service of the enterprise and are used to control the chemical composition of the ion-conducting electrolyte. The techniques do not require expensive equipment, and can be used in factory laboratories.
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Sianipar, Rut Novalia Rahmawati, Komar Sutriah, Dyah Iswantini, Trivadila e Suminar Setiati Achmadi. "Antigout Activity of The Spatholobus littoralis Hassk. Extract Fractions Against Xanthine Oxidase: Its Metabolite Profile and Inhibition Kinetics". HAYATI Journal of Biosciences 31, n. 1 (19 settembre 2023): 1–20. http://dx.doi.org/10.4308/hjb.31.1.1-20.
Testo completoAbstract (sommario):
The Spatholobus littoralis Hassk. (S. littoralis Hassk.) is a native plant in Indonesia and has been widely used in traditional Dayaknese medicine for non-communicable degenerative diseases. One of these illnesses, known as gout, is caused by excessive uric acid in the blood, which is the catalytic byproduct of a xanthine oxidase (XO) enzyme. In this work, we investigated the inhibition kinetics of XO and identified bioactive compounds from the stem extract fractions of S. littoralis Hassk. using liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Fractionation was carried out to obtain n-hexane, dichloromethane, and 1-butanol fractions from the water and 70% ethanol extracts. Fraction of 1-butanol from 70% ethanol and water extract displayed potent inhibitors of XO with IC50 value 116.91±3.51 and 137.15±5.00 mg/L, respectively. Lineweaver-Burk plot analysis showed that the 1-butanol fraction from the two extracts inhibited XO competitively. The 1-butanol fraction from the two extracts has been further identified as a bioactive fraction. The majority of the compounds in the two active fractions were phenolics. These findings revealed that the 1-butanol fraction from the two extracts is promising as an antigout treatment in the future.
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Tsuchikawa, T., H. Kaneda, S. Oyabu, T. Kokusho, H. Kobayashi, M. Yamagishi e Y. Toba. "A systematic study of silicate absorption features in heavily obscured AGNs observed by Spitzer/IRS". Astronomy & Astrophysics 651 (luglio 2021): A117. http://dx.doi.org/10.1051/0004-6361/202140483.
Testo completoAbstract (sommario):
Context. Heavily obscured active galactic nuclei (AGNs) are known to show deep silicate absorption features in the mid-infrared (mid-IR) wavelength range of 10–20 μm. The detailed profiles of the features reflect the properties of silicate dust, which are likely to include information on AGN activities obscured by large amounts of dust. Aims. We reveal AGN activities obscured by large amounts of dust through the silicate dust properties obtained from the mid-IR spectral bands. Methods. We selected 115 mid-IR spectra of heavily obscured AGNs observed by Spitzer/IRS and systematically analyzed the composition of silicate dust by spectral fitting using the 10 μm amorphous and 23 μm crystalline bands. Results. We find that the main component of the silicate dust obscuring AGNs is amorphous olivine, the median mass column density of which is one order of magnitude higher than those of the minor components of amorphous pyroxene and crystalline forsterite. The median mass fraction of the amorphous pyroxene, ∼2%, is significantly lower than that of the diffuse interstellar medium (ISM) dust in our Galaxy, while the median mass fraction of the crystalline forsterite, ∼6%, is higher than that of the diffuse ISM dust. We also find that the mass fractions of the amorphous pyroxene and the crystalline forsterite positively correlate with each other. Conclusions. The low mass fraction of the amorphous pyroxene suggests that the obscuring silicate dust is newly formed, originating from starburst activities. The relatively high mass fraction of crystalline forsterite implies that the silicate dust is processed in the high temperature environment close to the nucleus and transported to outer cooler regions by molecular outflows. The positive correlation between the mass fractions can be naturally explained considering that amorphous pyroxene is transformed from crystalline forsterite by ion bombardments. We also find that spectra with high ratios of the H2O ice absorption to silicate mass column density tend to indicate low mass fractions of amorphous pyroxene and crystalline forsterite, which is consistent with the scenario of the thermal dust processing close to the nucleus.
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Nie, Binghan, Zhongzhu Qiu, Yunpeng Zhang, Xingrui Ni, Miaomiao Zhang e Ning Xu. "The Performance of SiO2 Nanofluid-based Split-frequency PV/T Energy". Journal of Physics: Conference Series 2529, n. 1 (1 giugno 2023): 012023. http://dx.doi.org/10.1088/1742-6596/2529/1/012023.
Testo completoAbstract (sommario):
Abstract The efficiency of both solar photovoltaic and thermal power generation is relatively low, with the maximum panel temperature of conventional PV/T modules reaching 68.4 °C at noon, and the average electrical efficiency is only 12.98%. In this paper, the energy performance of a PV/T module based on SiO2 nanofluid was studied. Firstly, three different types of nanofluids, SiO2 nanofluid with a mass fraction of 0.3%, mass fraction of 0.5%, and mass fraction of 0.7%, were prepared and tested for their solar spectrum transmittance, and the results manifested that only the SiO2 nanofluid with 0.5% mass fraction exhibited strong absorption characteristics in the band after 400–1150 nm. Three liquid film thicknesses of 5 mm, 10 mm, and 15 mm, and three nanofluid mass fractions of 0.3%, 0.5%, and 0.7% were selected for the calculation of the spectral transmittance and the experiments on the thermal efficiency of the whole PV/T module. After conducting twenty-minute experimental tests on the power generation efficiency, thermal efficiency, and panel temperature of the flat panel, the results turned out the maximum efficiency reached 52.19%, which was found at a liquid film thickness of 10 mm and a nanofluid mass fraction of 0.7%, with a lower temperature of 40 °C, and an average of 10 °C lower than conventional PV panels.
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Gilhuly, Colleen, Allison Merritt, Roberto Abraham, Shany Danieli, Deborah Lokhorst, Qing Liu, Pieter van Dokkum, Charlie Conroy e Johnny Greco. "Stellar Halos from the The Dragonfly Edge-on Galaxies Survey". Astrophysical Journal 932, n. 1 (1 giugno 2022): 44. http://dx.doi.org/10.3847/1538-4357/ac6750.
Testo completoAbstract (sommario):
Abstract We present the primary results from the Dragonfly Edge-on Galaxies Survey, an exploration of the stellar halos of twelve nearby (d < 25 Mpc) edge-on disk galaxies with the Dragonfly Telephoto Array. The edge-on orientation of these galaxies allows their stellar halos to be explored with minimal obscuration by or confusion with the much brighter disk light. Galaxies in the sample span a range of stellar masses from 109.68 to 1010.88 M ⊙. We confirm that the wide range of stellar halo mass fractions previously seen for Milky Way–mass galaxies is also found among less massive spiral galaxies. The scatter in stellar halo mass fraction is large, but we do find a significant positive correlation between stellar halo mass fraction and total stellar mass when the former is measured beyond five half-mass radii. Reasonably good agreement is found with predictions from cosmological hydrodynamical simulations, although observed stellar halo fractions appear to be somewhat lower than expected from these simulations.
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Orlovskaya, S. G., V. V. Kalinchak, O. N. Zuj e M. V. Liseanskaia. "Study of Ignition and Combustion of Two-Fraction Coal-Air Suspension". Ukrainian Journal of Physics 63, n. 4 (18 giugno 2018): 370. http://dx.doi.org/10.15407/ujpe63.4.370.
Testo completoAbstract (sommario):
A two-fraction dust-air mixture is the simplest example of polydisperse suspensions. We aim to study the characteristics of ignition and combustion of a two-fraction suspension of carbon particles in air at different temperatures. The main characteristics of the dispersed fuel combustion are the ignition delay, burning temperature and time, and critical parameters (temperature, diameters of particles, and mass concentrations) corresponding to the fuel ignition and extinction. The high-temperature heat and mass transfer and chemical kinetics are modeled for a two-fraction particles-gas suspension (diameter of fine particles 60 мm and for that with coarse particles 120 мm) with equal mass fractions. The gas temperature is varied in the interval between 1100 K and 1500 K.
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Balasubramani, Jegan, Kumaraguruparan Gurusamy e varun Balakrishnan. "Experimental investigation on the thermophysical properties of the ionic liquid-based binary system for heat transfer applications". Thermal Science, n. 00 (2023): 31. http://dx.doi.org/10.2298/tsci221102031b.
Testo completoAbstract (sommario):
Based on the innovation in the development of Ionic Liquids (IL), the aim of the present work is to investigate the thermophysical properties of novel hydrophilic ionic liquid 1-Ethyl-3-Methyl Imidazolium Tetra FluoroBorate (EMIMBF4) and water as binary systems experimentally at various mass fraction and at various temperatures. A Room-Temperature Ionic Liquid blended with deionized water in four different mass fractions as 20%, 15%, 10%, and 5% to prepare an ionic liquid and water binary mixture at room temperature. Thermal stability and the thermophysical characteristics of EMIMBF4 such as thermal conductivity (TC), specific heat capacity, viscosity, and density, were measured in the temperature range of 25?C to 90?C. The results reveal that the specific heat capacity increased by 13 %, and TC enhanced 9%, at 5wt% mass fraction. The overall mass drop is reached 75.1 % at 20 wt % mass fractions.
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Pitkänen, Leena, e Herbert Sixta. "Size-exclusion chromatography of cellulose: observations on the low-molar-mass fraction". Cellulose 27, n. 16 (9 settembre 2020): 9217–25. http://dx.doi.org/10.1007/s10570-020-03419-9.
Testo completoAbstract (sommario):
AbstractAccurate determination of molar mass distribution for disperse cellulose samples has proved to be a challenging task. While size-exclusion chromatography coupled to multi-angle light scattering (MALS) and differential refractive index (DRI) detectors has become the most commonly used method for molar mass determination of celluloses, this technique suffers low sensitivity at the low-molar mass range. As discussed here, the universal method for accurate molar mass distribution analysis of cellulose samples not exists and thus thorough understanding on the differences of the various methodological approaches is important. In this study, the focus is in the accurate determination of the low-molar mass fraction. The results obtained by combining the two calibration strategies, MALS/DRI for polymeric region of a cellulose sample and conventional calibration for oligomeric region, was compared to the results obtained using only MALS/DRI (with extrapolation of the curve where signal-to-noise of MALS is low). For birch pulp sample, the results from the two approaches were comparable; it should be highlighted, however, that MALS/DRI slightly overestimates the molar masses at the low-molar-mass region.
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García-Pérez, J. V., M. Blasco, J. A. Cárcel, G. Clemente e A. Mulet. "Drying Kinetics of Grape Stalk". Defect and Diffusion Forum 258-260 (ottobre 2006): 225–30. http://dx.doi.org/10.4028/www.scientific.net/ddf.258-260.225.
Testo completoAbstract (sommario):
Grape stalk may be considered as an agro-food byproduct of the wine industry, being considered as a potential source of antioxidant compounds. Actually, before the extraction of antioxidants a previous stage of drying would be necessary. Stalks obtained from a red wine processing (Vitis vinifera var. Bobal) were characterized as a cylinder net with different size ending in spheres. The average diameters and mass fractions of the individual parts of the stalk were measured: spheres (4.4±0.7 mm and 0.352 mass fraction), large cylinders (3.3±0.6 mm and 0.204 mass fraction), intermediate cylinders (2.1±0.4 mm and 0.294 mass fraction) and small cylinders (1.1±0.3 mm and 0.150 mass fraction). Drying kinetics of each one of the parts of the stalk were carried out at 40 °C and 2 m/s using an initial mass load of 30 g. Furthermore, drying experiments of the whole stalk were conducted at the same experimental conditions. Different diffusion models were considered to predict the drying kinetics for each one of the individual parts of the stalk according to the geometry considered. A diffusion model for the whole stalk was developed by adding the individual diffusion models weighed by the corresponding mass fractions. The diffusion models considered fitted properly the drying kinetics of the individual parts considered on the stalk. The figures of the effective moisture diffusivity identified for the different kinds of cylinders were close (1.07-1.78 10-11 m2/s), however, the spheres showed a different behavior characterized by a significantly higher figure of effective moisture diffusivity (3.92 10-8 m2/s). Finally, the usefulness of the model considered to describe the drying kinetics of the whole stalks was shown.
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Abdullah, Adli Zil Ikram, Mohd Fadzli bin Abdollah, Boon Tuan Tee, Hilmi Amiruddin, Ahmad Kamal Mat Yamin e Noreffendy Tamaldin. "Thermal Conductivity and Latent Heat Properties of Microencapsulated Phase Change Material (μPCM)/Multiwall Carbon Nanotube (MWCNT) Composites for EVs Application". Advanced Materials Research 1133 (gennaio 2016): 131–35. http://dx.doi.org/10.4028/www.scientific.net/amr.1133.131.
Testo completoAbstract (sommario):
The aim of this study is to investigate the thermal properties of microencapsulated phase change material (μPCM) / multiwall carbon nanotube (MWCNT) composites. Several disc samples with 30mm diameter x 5mm width of μPCM/MWCNT composites were prepared with different mass fractions of MWCNT of 2, 4, 7 and 10 wt% using a compaction method. The thermal conductivity test was performed according to ASTM standard, while the latent heat property was calculated based on the theoretical equations. It was found that the thermal conductivity increase with mass fraction of MWCNT. However, the latent heat decreases with mass fraction of MWCNT. From these results, the optimized mass fraction of MWCNT approximately 5%, could be selected due it stable-form in thermal conductivity and latent heat capacity for electric vehicles (EVs) application. Furthermore, the reducing in melting time with increasing of MWCNT is accordance with the improvement of thermal conductivity.
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Zhu, Jian Jun, Xiao Fen Li e Tie Wang. "Simulation Study on Combustion and Emission Process of High Proportional of DME-Diesel Mixed Fuel". Advanced Materials Research 129-131 (agosto 2010): 1186–90. http://dx.doi.org/10.4028/www.scientific.net/amr.129-131.1186.
Testo completoAbstract (sommario):
With the ESE module of FIRE software, this paper establishes the diesel engine model of 4100, and verifies the correctness with the test result. Based on this, the paper carries on a simulation on three high proportions of DME-diesel D65, D75 and D85, and makes a contract with diesel on the mean pressure, mean temperature, mass fraction, accumulated heat release, as well as the mass fraction of NOx and soot. The result shows that the higher proportional, the lower mean pressure in-cylinder. Also the result shows that NOx growth will come to a “freezing period” when it comes to a certain temperature, while soot growth is growing first and oxygenated later, and with the increase of DME proportion, NOx grows later and its mass fraction is lower. Besides, the mass fractions of soot of three kinds of mixed fuels are far below diesel’s, D85’s is the lowest.
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Mukherjee, Sampath, Léon V. E. Koopmans, Crescenzo Tortora, Matthieu Schaller, R. Benton Metcalf, Joop Schaye e Georgios Vernardos. "SEAGLE – III: Towards resolving the mismatch in the dark-matter fraction in early-type galaxies between simulations and observations". Monthly Notices of the Royal Astronomical Society 509, n. 1 (20 ottobre 2021): 1245–51. http://dx.doi.org/10.1093/mnras/stab3014.
Testo completoAbstract (sommario):
ABSTRACT The central dark-matter fraction of galaxies is sensitive to feedback processes during galaxy formation. Strong gravitational lensing has been effective in the precise measurement of the dark-matter fraction inside massive early-type galaxies. Here, we compare the projected dark-matter fraction of early-type galaxies inferred from the SLACS (Sloan Lens ACS Survey) strong-lens survey with those obtained from the Evolution and Assembly of GaLaxies and their Environment (EAGLE), Illustris, and IllustrisTNG hydrodynamical simulations. Previous comparisons with some simulations revealed a large discrepancy, with considerably higher inferred dark-matter fractions – by factors of ≈2–3 – inside half of the effective radius in observed strong-lens galaxies as compared to simulated galaxies. Here, we report good agreement between EAGLE and SLACS for the dark-matter fractions inside both half of the effective radius and the effective radius as a function of the galaxy’s stellar mass, effective radius, and total mass-density slope. However, for IllustrisTNG and Illustris, the dark-matter fractions are lower than observed. This work consistently assumes a Chabrier initial mass function (IMF), which suggests that a different IMF (although not excluded) is not necessary to resolve this mismatch. The differences in the stellar feedback model between EAGLE and Illustris and IllustrisTNG are likely the dominant cause of the difference in their dark-matter fraction and density slope.
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Cho, Hojin, e Jong-Hak Woo. "Constraining the Low-mass End of the Black Hole Mass Function and the Active Fraction of the Intermediate-mass Black Holes". Astrophysical Journal 969, n. 2 (1 luglio 2024): 93. http://dx.doi.org/10.3847/1538-4357/ad4966.
Testo completoAbstract (sommario):
Abstract We investigate the black hole mass function (BHMF) and the Eddington ratio distribution function (ERDF), focusing on the intermediate-mass black holes (IMBHs) with masses down to M • ∼ 104 M ⊙. Based on the active galactic nuclei (AGNs) with a detected broad Hα emission line, we construct a sample of 14,242 AGNs at redshift z < 0.35, including 243 IMBHs with M • < 106 M ⊙. By jointly modeling the BHMF and ERDF via the maximum posterior estimation, we find that the BHMF peaks at ∼106 M ⊙ and exhibits a relatively constant value of 10−4 Mpc−3 dex−1 at the low-mass end. By comparing the derived BHMF of type 1 AGNs with the galaxy mass function based on the updated black hole mass–host galaxy stellar mass relation, we derive the active fraction. We also determine the active fraction for all AGNs using the upper and lower limit of the type 1 fraction. The active fraction decreases from 15%–40% for massive galaxies (M ⋆ > 1010 M ⊙) to lower than ∼2% for dwarf galaxies with M ⋆ ∼ 108 M ⊙. These results suggest that the black hole occupation fraction is expected to be ∼50% for low-mass galaxies (M ⋆ ∼ 108.5–109 M ⊙) if the duty cycle is similar between IMBHs and supermassive black holes.