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排序方式: 共有159条查询结果,搜索用时 15 毫秒
71.
Mariam Shenasi Alan A
G Candlish Kofi E Aidoo 《Journal of the science of food and agriculture》2002,82(8):848-853
Sixteen varieties of date fruit (Phoenix dactylifera) at three stages of maturation (Kimri, Rutab and Tamr) were examined for the presence of fungi and analysed for aflatoxins B1, B2, G1 and G2 and sterigmatocystin. Single samples of each variety were used in the study. Samples as received were initially examined for mycoflora and toxin levels and then stored at 98% relative humidity and 30 °C for 14 days to investigate the effects of possible adverse storage conditions on mycoflora and, in particular, aflatoxin formation. All samples showed an absence of aflatoxins and their precusor, sterigmatocystin, after adverse storage for 14 days, although aflatoxin‐producing Aspergillus flavus isolates were identified in 10 varieties at the first stage of maturation (Kimri). High fungal counts were associated with the Rutab stage and low counts with the Tamr stage. The counts of A flavus ranged from 5.00 to 8.16 log10(cfu g?1) under simulated storage conditions, and three varieties contained significant levels of aflatoxin B1 or B2 ranging from 35 to 11 610 µg kg?1. Sterigmatocystin was not detected in any of the samples as received or under simulated storage conditions. © 2002 Society of Chemical Industry 相似文献
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73.
Restricted and unrestricted (U) Hartree-Fock (HF), second-order M?ller-Plesset perturbation (MP2), density functional (DF), hybrid HF/DF and semiempirical (half-electron (HE) method) models have been used to calculate adiabatic electron affinities (EAad values) of p-benzoquinone (I), p-benzoquinone imine (VI) and p-benzoquinone diimine (XI), as well as expectation values () and spin density distributions in the radical anions of I, VI and XI. The AM1/AM1-HE and ab initio calculated structures are found to be in accord with each other. The ROHF/6-31G(d) method gave the poorest EAad result. The UHF and UMP2 wave functions were found to be substantially spin contaminated (for the radicals) and the accuracies of the EAad values calculated were also poor. The use of molecular energies obtained after spin annihilation did not lead to significant improvement of the UHF and UMP2 results. In contrast to the ROHF, UHF and UMP2 results, the DF(USVWN, UBVWN, UBLYP) and hybrid HF/DF(UB3LYP) methods, as well as the AM1-HE, gave much better results. The calculated EAad values decreased, as predicted by most of the models, in the order EAad(I) > EAad(VI) > EAad(XI). The differences in the EAs, EAad(I)-EAad(VI) and EAad(I)-EAad(XI), were consistently predicted to be about 8-9 and 17-18 kcal/mol, respectively, by the DF, B3LYP and AM1-HE models. The performance of the PM3 and SAM1 models was not as good as the AM1 model. Of all the methods tested, the B3LYP/6-311G(d,p) model is concluded to give the most accurate quantitative trend (I(42.6) > VI(33.1) > XI(23.7)) in EAad. The predicted trend in EA can satisfactorily be rationalized by the calculated LUMO orbital energies, atomic charges and spin density distributions. Analysis of the spin density data predicts that phenoxyl- and anilino-type radical anions predominate in the p-benzosemiquinones of I and XI, respectively, while both phenoxyl- and anilino-type radicals contribute to the structure of the p-benzosemiquinone of VI, with the anilino-type predominating. 相似文献
74.
75.
It's a part of the process: People try to deceive their adversaries in negotiations. Jeffrey Krivis and Mariam Zadeh, of Los Angeles, describe the science of deception, and then provide two lists of cues that you can watch for to minimize the chances of being deceived in mediation. 相似文献
76.
Annegret Stark Mariam Ajam Mike Green Helgard G. Raubenheimer Alta Ranwell Bernd Ondruschka 《Advanced Synthesis \u0026amp; Catalysis》2006,348(14):1934-1941
With the self‐metathesis of 1‐octene to 7‐tetradecene catalyzed by Grubbs 1st generation [benzylidene‐bis(tricyclohexylphosphine)dichlororuthenium, ( 1 )] precursor at low concentrations (0.02 mol %) as basis, the effects of the solubility of the substrate in ionic liquids, the solvent polarity, as well as the influence of various impurities stemming from the preparation of ionic liquids have been investigated. The solubility of the substrate in the ionic liquid has little effect on the conversion, and the reaction is not mass‐transfer limited. While a higher polarity of an organic solvent increases the rate, it is independent of the polarity excerted by the cation of an ionic liquid. Of paramount importance for reproducible results is the purity of ionic liquids. An extensive study shows that catalyst deactivation by impurities increases in the order of water<halide<1‐methylimidazole. In the presence of water or 1‐methylimidazole impurities, the Grubbs‐Hoveyda precursor ( 3 ) is superior to both the 1st ( 1 ) and 2nd ( 2 ) generation Grubbs complexes. Under impurity‐free conditions or in the presence of chloride, the performance of 2 is equivalent to that of 3 . 相似文献
77.
Eleonora Patsenker Philip Sachse Andrea Chicca María Salomé Gachet Vreni Schneider Johan Mattsson Christian Lanz Mathias Worni Andrea de Gottardi Mariam Semmo Jochen Hampe Clemens Schafmayer Rudolf Brenneisen Jürg Gertsch Felix Stickel Nasser Semmo 《International journal of molecular sciences》2015,16(4):7057-7076
The endocannabinoid (EC) system is implicated in many chronic liver diseases, including hepatitis C viral (HCV) infection. Cannabis consumption is associated with fibrosis progression in patients with chronic hepatitis C (CHC), however, the role of ECs in the development of CHC has never been explored. To study this question, anandamide (AEA) and 2-arachidonoyl glycerol (2-AG) were quantified in samples of HCV patients and healthy controls by gas and liquid chromatography mass spectrometry. Fatty acid amide hydrolase (FAAH) and monoaclyglycerol lipase (MAGL) activity was assessed by [3H]AEA and [3H]2-AG hydrolysis, respectively. Gene expression and cytokine release were assayed by TaqMan PCR and ELISpot, respectively. AEA and 2-AG levels were increased in plasma of HCV patients, but not in liver tissues. Hepatic FAAH and MAGL activity was not changed. In peripheral blood mononuclear cells (PBMC), ECs inhibited IFN-γ, TNF-α, and IL-2 secretion. Inhibition of IL-2 by endogenous AEA was stronger in PBMC from HCV patients. In hepatocytes, 2-AG induced the expression of IL-6, -17A, -32 and COX-2, and enhanced activation of hepatic stellate cells (HSC) co-cultivated with PBMC from subjects with CHC. In conclusion, ECs are increased in plasma of patients with CHC and might reveal immunosuppressive and profibrogenic effects. 相似文献
78.
In this work, LLDPE‐based composite films were prepared by melt mixing followed by compression molding to investigate the role of titanium oxide nanoparticles (TONPs) and/or multiwalled carbon nanotubes (CNTs) on the accelerated weathering samples (maximum of 39 days). Accelerating weathering caused the emerging of oxidation peaks in the FT‐IR spectra for LLDPE and LLDPE/TONPs. These peaks were not pronounced in the LLDPE/CNTs samples. The same prevention of oxidation peaks were noticed for the hybrid additives samples. Tensile properties decreased by exposing the composite samples to accelerating weathering. TONPs increased the tensile strength of the samples by 11.5% but deterioration of this property is the same as the pristine sample after accelerated weathering for 39 days. Addition of CNTs had negligible effect on the tensile strength but it kept the same approximate value of the original before the accelerated weathering (e.g., 23.2 MPa for 1 wt% of CNTs). CNTs also protected the samples even with the presence of TONPs because of the absorbance and antioxidants effects. The addition of CNTs into LLDPE network have not only retarded decomposition of LLDPE but also decreased catalytic activity of TONPs to activate degradation due to accelerated weathering. J. VINYL ADDIT. TECHNOL., 25:19–25, 2019. © 2018 Society of Plastics Engineers 相似文献
79.
Irfana Mariam Ki Yul Cho Syed S.H. Rizvi 《International Journal of Food Properties》2013,16(2):415-426
Starch-based extruded foams are in demand for many industrial applications because starch is biodegradable, inexpensive, and readily available in abundant quantity. In this study, the production of starch-based extruded foams using supercritical fluid extrusion (SCFX) having thermal properties such as heat capacity, thermal conductivity and thermal diffusivity comparable to commercial products have been reported. Pregelatinized corn starch was extruded with different concentrations of whey protein isolate (WPI) (0, 12, and 18 wt. %) with supercritical CO2 (SC-CO2) injection rates of 0.0, 0.4, 0.8, and 1.2 wt%. It was possible to vary the expansion and the density of SCFX extrudates by manipulating WPI concentration and SC-CO2 injection rate. It was observed that the heat capacity, thermal conductivity and thermal diffusivity of starch-based SCFX extrudates were strong functions of their void fraction. The SCFX system is a useful tool for production of starch-based biodegradable foams, which do not require any organic solvents and are environmentally friendly and sustainable. 相似文献