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A suitable Stillinger–Weber (SW) potential energy function parameter set is developed for finite boron structures by genetic algorithm and trial error techniques. Boron structure geometries in 7–24 atoms range, calculated by ab initio methods, are taken as the fitting criteria in the parameter set development. This parameter set is used together with another SW parameter set developed for carbon–carbon interactions in order to investigate boron carbide nanoparticles in the form of BxCx where 8 ? x ? 14. In addition, B80C12 nanoparticle structure is investigated using local optimization technique. 相似文献
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Brandon Moore Chris Grinnell Boris Boumajny Rachel Chen Ruth Frenkel Phil de Vilmorin Zoran Sosic Sarwat Khattak 《American Institute of Chemical Engineers》2020,66(9):e16295
Glucose solutions are commonly heated before use in medical and biotech applications to maintain cleanliness, however the resulting degradants can be toxic. This study examines two approaches to evaluating the heat degradants resulting from holding a 40% glucose solution at 55°C for 5 weeks: first, chemical changes to the solution were identified and quantified via analytical testing, and second the toxicity of the heat-degraded 40% glucose solution was evaluated empirically by using it as a feed stock for a fed-batch CHO-cell-based protein therapeutic manufacturing process. Colorimetric analysis quantified a color change during heating, and liquid chromatography assays measured an increase in the concentrations of two unknown degradants along with the commonly identified glucose impurity 5-hydroxymethylfurfural (5-HMF). Solution pH decreased over time, corresponding with an increase in formic acid concentration as measured via GC–MS. Despite this, cell culture toxicity was not observed, and protein productivity and product quality were maintained. 相似文献
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Fawad Tariq Nausheen Naz Rasheed Ahmed Baloch Faisal 《Journal of Nondestructive Evaluation》2012,31(1):17-33
2xxx series Al-alloys are widely employed in structural applications due to their good mechanical properties. During heat
treatment of these alloys, solution treated parts sometimes mixed with age hardened parts during handling. This result in
difficulty in distinguishing between solution treated and aged parts of various grades. Moreover, it is also necessary to
separate improper aged parts from properly treated parts. The traditional methods of characterization of different heat treated
parts are hardness, tension testing and microscopy, however these are destructive in nature and sometimes not desired particularly
for finished products. The main purpose of this paper is characterization of material properties of 2xxx series Al-alloys
by eddy current and ultrasonic NDE techniques so that the inspection can be carried out effectively in the shortest possible
time. Three wrought Al-alloys of 2xxx series (AA 2014, AA 2024 and AA 2219) were homogenized followed by solution heat treatment
and age hardening treatments at specific temperatures for 1–16 h. The changes in hardness and microstructure during heat treatments
were determined by traditional material characterization methods and then correlated with electrical conductivity, sound velocity
and attenuation coefficient obtained through Nondestructive Evaluation (NDE) techniques. Results demonstrated an excellent
correlation between hardness and sound velocity, whereas extend of aging can be easily predicted by electrical conductivity,
and attenuation coefficient measurement. Investigation suggested a way towards the non-destructive detection and characterization
of material properties when conventional testing methods are not applicable. 相似文献
56.
Majid?ArvandEmail author Naz?Chaibakhsh Samaneh?Daneshvar 《Food Analytical Methods》2015,8(8):1911-1922
In this paper, Fe3O4@ZnO core/shell magnetic nanoparticles (MNPs) have been synthesized by a simple method, to modify carbon paste/glassy carbon electrode and improve its efficiency for determination of quercetin. The synthesized MNPs were characterized by X-ray powder diffraction (XRD), transmission electronic microscope (TEM), and scanning electronic microscope (SEM). SEM and TEM results show that the prepared Fe3O4@ZnO MNPs are made of the spherical shape particles with an average size of about 15 nm. The electrochemical behavior of quercetin at the surface of modified electrode was investigated. Under the optimal conditions, a linearity range of quercetin was 7.9?×?10?7 to 6.1?×?10?5 mol/L (0.24–18.44 mg/L) with detection limit (S/N?=?3) and sensitivity of 0.16 μmol/L (0.048 mg/L) and 0.04 μA/μM, respectively. The validated method was applied successfully for determination of quercetin in some foods and human breast milk. 相似文献
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Blends of bisphenol A polycarbonate (PC) and polyamide 6,6 (PA6,6) were prepared directly during the plasticization step of an injection molding process in an attempt to attain both (i) the reinforcement of the blends through fibrillar morphology, and (ii) an adequate compatibilization despite the short processing procedure used. Differential scanning calorimetry and dynamic‐mechanical analysis indicated that the blends were made up of a PC‐rich phase where some PA6,6 was present and, ruling out a possible degradation, of an almost pure PA6,6‐phase. The cryogenically fractured surfaces observed by scanning electron microscopy showed both rather fine particles and larger particles with occluded subparticles. This complex morphology indicates low interphase tension and, therefore, compatibilization, which can be attributed to the presence of PA6,6 in the two phases of the blends. The values of Young's modulus, determined by means of tensile tests, were always synergistic and, in the case of the 25/75 blend, the modulus was even higher than those of any of the two pure components. It appears this could be due to both the highly fibrillar morphology of the dispersed phase, and the significant decrease observed in specific volume. The blends remained ductile throughout the full composition range, which also indicates compatibilization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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Farooq Anwar Rehana Naseer M. I. Bhanger Samia Ashraf Farah Naz Talpur Felix Adekunle Aladedunye 《Journal of the American Oil Chemists' Society》2008,85(4):321-330
The physico-chemical characteristics of the seeds and seed oils of four citrus species, Mitha (Citrus limetta), Grapefruit (Citrus paradisi), Mussami (Citrus sinensis), and Kinnow (Citrus reticulata) were investigated. The hexane-extracted oil content of citrus seeds ranged from 27.0 to 36.5%. The protein, fiber and ash
contents were found to be 3.9–9.6%, 5.0–8.5%, and 4.6–5.6%, respectively. The extracted oils exhibited an iodine value of
99.9–110.0; refractive index (40 °C), 1.4639–1.4670; density (24 °C), 0.920–0.941 mg/mL; saponification value, 180.9–198.9;
unsaponifiable matter, 0.3–0.5%; acid value (mg KOH/g of oil), 0.5–2.2 and color (1-in. cell) 1.4–3.0R + 15.0–30.0Y. The oils
revealed a good oxidative stability as indicated by the determinations of specific extinctions at 232 and 270 nm (2.3–4.4
and 0.6–0.9, respectively), p-anisidine value (2.2–3.2) and peroxide value (1.6–2.4 mequiv/kg of oil). The citrus seed oils mainly consisted of linoleic
acid (36.1–39.8%). Other prominent fatty acids were palmitic acid (25.8–32.2%), oleic acid (21.9–24.1%), linolenic acid (3.4–4.4%),
and stearic acid (2.8–4.4%). The contents of tocopherols (α, γ, and δ) in the oil were 26.4–557.8, 27.7–84.1, and 9.1–20.0 mg/kg,
respectively. The results of the present study demonstrated that the seeds of citrus species investigated are a potential
source of valuable oil which might be utilized for edible and other industrial applications. 相似文献