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131.
G. Keller F. Lavigne C. Loisel M. Ollivon C. Bourgaux 《Journal of Thermal Analysis and Calorimetry》1996,47(5):1545-1565
The thermal behavior of three ural fats (displaying very different composition), cocoa butter (CB)2, lard, and a stearin obtained from anhydrous milk-fat (AMF) fractionation, were studied by both DSC and X-ray diffraction as a function of temperature (XRDT). To perform temperature explorations between –30C and +80C, at rates identical to those used for DSC and ranging from 0.1 K min–1 to 10 K min–1, a new set of X-ray sample-holders, temperature-controlled by Peltier effect, has been developed. It is shown that the three more stable polymorphic forms of CB were easily characterized by either X-ray diffraction or DSC, and existence of two -3L forms was confirmed. On the contrary, the more complex polymorphism of lard and AMF required combined examination by DSC and XRDT and the brightness of the synchrotron source for studies at the highest heating rates. Quantitative analysis of the long spacings of XRDT recordings is invaluable for interpretation of thermal events. For instance, it was found that the simultaneous formation of two polymorphic forms, of apparent long spacing of 34 and 42 å, at the onset of lard crystallization might explain the difficulty of its fractionation.Special thanks to Courtney P. Mudd (NIH, Bethesda) for his pertinent advice on the mounting and use of thermoelectric devices. The study of lard crystallization was initiated by Valerie Portalier and suggested by Jean-Luc Vendeuvre of CTSCCV (Maisons-Alfort). For the AMF part of this study, stearin was fractionated by ADRIA Normandie, while characterization of its thermal properties was performed as part of a research program funded by ARILAIT Recherches and the French Ministry of Research and Technology. 相似文献
132.
D. L. Gardner C. M. Kjellstrand C. R. Hassler D. J. Fink D. C. Emmerling 《Applied biochemistry and biotechnology》1984,10(1-3):27-40
Ingestible adsorbents for the removal of uremic metabolites are being investigated as adjunctive therapy in the treatment
of chronic uremia. In particular, a microcapsule product containing urease and zirconium phosphate (UZP) has been investigated
for removing urea. A dog model, simulating chronic uremia, was developed to investigate: (1) the concentration of various
nitrogenous metabolites (urea, creatinine, and uric acid) in the GI tract, (2) flux rates of H2O and various nitrogenous metabolites in the GI tract, and (3) the efficacy of the microcapsule product. The results of these
perfusion studies suggest that urea and creatinine can be removed from the GI tract via ingestible adsorbents. In addition,
the model may be useful in investigating suspect uremic toxins, e.g., guanidinosuccinic acid (GSA). The reduction of blood
urea nitrogen levels in the dog model when the animal was fed the microcapsule product was limited by the capacity of the
zirconium phosphate to bind ammonium ion. Preliminary clinical studies with the microcapsule product indicate that it may
be of potential adjunctive therapy in patients suffering from chronic renal failure. 相似文献
133.
高效液相色谱法测定动物组织中四环素类抗生素残留量的研究 总被引:8,自引:0,他引:8
建立了动物组织中四环素、金霉素、土霉素、强力霉素、去甲基金霉素、甲烯土霉素和二甲胺四环素等7种四环素类抗生素残留量的液相色谱同时测定方法。方法采用Inertsil C8-3(5μm,250 mm×4.0 mm i.d)反相色谱柱,以pH 4.0的EDTA-Mcllvaine缓冲溶液为提取溶液,以HLB固相萃取柱为净化柱,流动相为甲醇+乙腈+0.01mol/L三氟乙酸(梯度洗脱),流速1.5 mL/min,检测波长350 nm,进样量100μL。方法的检出限为1.5~5.0μg/kg,测定低限为50μg/kg,线性范围为50~1200μg/kg,加标回收率为73.8%~103%,相对标准偏差为0.5%~8.5%。方法适用于动物肌肉、肝脏和肾脏组织中7种四环素类抗生素残留量的同时检测。 相似文献
134.
135.
热裂解气相色谱法测定动物源性食品中敌百虫残留量 总被引:3,自引:0,他引:3
通过对热裂解气相色谱及气-质联用技术测定动物源性食品中敌百虫的探讨,建立了气相色谱进样口裂解产物的检测方法,并确定了气相色谱的主要分析条件(进样口280℃,DB-225毛细管色谱柱及FPD检测器)。样品前处理结合动物源性食品的特点,采用V(乙腈)∶V(水)=9∶1提取,乙酸锌水解除酯,并利用三氯化碳相转移的方式,建立了一套前处理方法。检测方法的回收率在80.7%~96.5%之间,RSD<5.5%,线性相关系数为0.9991,检出限为0.02mg/kg。该方法是按照我国关于兽药残留分析方法要求建立的,适合进出口及日常动物源性食品中敌百虫残留量的检测。 相似文献
136.
Fix integers n, x, k such that n≥3, k>0, x≥4, (n, x)≠(3, 4) and k(n+1)<(
n
n+x
). Here we prove that the order x Veronese embedding ofP
n
is not weakly (k−1)-defective, i.e. for a general S⊃P
n
such that #(S) = k+1 the projective space | I
2S
(x)| of all degree t hypersurfaces ofP
n
singular at each point of S has dimension (
n
/n+x
)−1− k(n+1) (proved by Alexander and Hirschowitz) and a general F∈| I
2S
(x)| has an ordinary double point at each P∈ S and Sing (F)=S.
The author was partially supported by MIUR and GNSAGA of INdAM (Italy). 相似文献
137.
138.
Cátia Crispilho Corrêa Lucimara Aparecida Forato Luiz Alberto Colnago 《Analytical and bioanalytical chemistry》2009,393(4):1357-1360
High intake of saturated fat from meats has been associated with cardiovascular disease, cancer, diabetes, and others diseases.
In this paper, we are introducing a simple, high-throughput, and non-destructive low-resolution nuclear magnetic resonance
method that has the potential to analyze the intramuscular fat content (IMF) in more than 1,000 beef portions per hour. The
results can be used in nutritional fact labels, replacing the currently used average value. The method is based on longitudinal
(T
1) and transverse (T
2) relaxation time information obtained by a continuous wave-free precession (CWFP) sequence. CWFP yields a higher correlation
coefficient (r = 0.9) than the conventional Carr-Purcell-Meiboom-Gill (CPMG) method (r = −0.25) for IMF in beef and is just as fast and a simpler pulse sequence than CPMG. The method can also be applied to other
meat products. 相似文献
139.
C. Juan C. Igualada F. Moragues N. León J. Mañes 《Journal of chromatography. A》2010,1217(39):6061-6068
A reproducible, sensitive and selective multiresidue analytical method for seven β-agonists: clenbuterol (CBT), clenpenterol (CPT), ractopamine (RTP), brombuterol (BBT), mabuterol (MBT), mapenterol (MPT), and hydroxymethylclenbuterol (HMCBT) was developed and validated by using liquid chromatography tandem mass spectrometry (LC–MS/MS) in feed and drinking water samples. The validation was achieved according to the criteria laid down in the Commission Decision 2002/657/EC, however it was necessary to use minimum required performance limits (MRPLs) proposed by the Community Reference Laboratories (CRLs) due to the lack of maximum residue limits (MRLs) for β-agonists. By setting up these MRPLs, allows controlling their use in safe mode, since β-agonists are commonly used in veterinary medicine sometime in a fraudulent manner, for increasing the weigh of animals. Values set for both matrices studied are 50 μg/kg for animal feed, and a range from 0.2 to 10 μg/L for drinking water. CCα values calculated were under the MRPLs suggested; for drinking water the lowest value obtained was 0.12 μg/L, and for animal feed 0.87 μg/kg. Values for CCβ were ranged from 0.08 to 0.13 μg/L in drinking water and from 0.5 to 0.92 μg/kg in animal feed samples. The excellence values obtained, allowed us to conclude that the proposed analytical method is capable to control the β-agonists studied in both matrices and that it can be successfully applied and used as a routine method in laboratories of residue analysis of veterinary food control. 相似文献
140.
The mathematical model of heat transfer between the counter flows of gas and porous batch of anthropogenic wastes in the working
area of a shaft furnace is presented. This model considers chemical transformations in separate batch components and radiation
heat transfer between the gas and solid phases. Results of calculations are presented. 相似文献