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In industrialized countries, the epidemiology of infec- tious diseases with indirect transmission through water and foodstuffs has undergone considerable changes over the past decades with the almost total disappearance of some traditional pathogen microo…  相似文献   

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《Journal of dairy science》2022,105(5):4116-4127
Whether supplemental dietary β-carotene affects periparturient cows and vitamins A and E in cows when dietary vitamin A is adequate remains uncertain. Our objective was to assess the effect of β-carotene supplementation during the close-up dry period in a herd with adequate status of vitamins A and E but low in β-carotene. The study was conducted on a large commercial dairy farm in Indiana during early summer of 2015. Ninety-four multiparous Holstein cows were assigned to either control (CON; n = 47) or β-carotene (BC; n = 47) treatments. When locked in headgates each morning, each cow received a topdress of β-carotene (Rovimix, 8 g/d; provided 800 mg of β-carotene) or carrier from 21 d before expected calving until calving. Blood samples were collected at 21 ± 1 d (mean ± standard deviation) before expected calving (before treatments began), 7 ± 1 d before calving, immediately following parturition, and 7 ± 1 d postpartum. Blood serum was analyzed for vitamins A and E, β-carotene, cholesterol, and other metabolites and enzymes. Data were analyzed using the MIXED procedure in SAS (SAS Institute Inc.). Cows had low β-carotene concentrations (0.85 μg/mL) in blood serum before treatments began. Compared with CON cows, BC cows had higher overall mean concentrations of β-carotene (2.87 μg/mL vs. 0.73 μg/mL) and retinol (165 vs. 143 ng/mL). Cows fed BC had lower α-tocopherol in serum than cows fed CON (2.26 vs. 2.46 µg/mL). Cows fed BC had lower peak milk than cows fed CON (50.9 vs. 55.3), but total lactation milk yield did not differ significantly. No effects of BC were observed on days to conception (100 d) or times bred (2.4). Treatments did not affect incidences of ketosis, retained placenta, displaced abomasum, off feed, lameness, footrot, mastitis, or metritis. In conclusion, in pregnant cows already receiving adequate vitamin A but with low serum β-carotene concentration, supplementation of β-carotene increased concentrations of β-carotene and vitamin A in blood serum, but did not affect production, reproduction, or health.  相似文献   

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Recently, leading textile machinery manufacturers in Chinahave adjusted their strategy to a market-oriented and profit-based one. They spent greater efforts on technical innovation,aimed at improving the mechanical-electrical integration levelof textile machinery and making them more competitive on amarket requiring small batch, diversified variety and quickresponse. As a result, they have developed a batch of high-quality new textile machinery that can adapt to the need onmarket. These produc…  相似文献   

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While the mechanism of gelation of carrageenan in an aqueous environment, via a coil–helix transition followed by aggregation, is well accepted, its behaviour in highly concentrated sugar is still not well understood. Therefore, the effect of biopolymer and salt concentration on the gelling properties of κ-carrageenans in the presence of high concentrations of sugars was investigated rheologically. A solution of 1% κ-carrageenan in the presence of 10 mM KCl and 87.5% corn syrup did not form a measurable network whereas 1% κ-carrageenan in the presence of 10 mM KCl in aqueous solution forms a gel. Gelation was again observed as KCl concentration was increased to 40 mM KCl. An increase of κ-carrageenan concentration from 1 to 2% with 10 mM KCl present did not restore the capacity for gelation. The effect of type of the sugar solution was also investigated by substituting a corn syrup/glucose syrup mixture for the original corn syrup. In the presence of corn syrup/glucose syrup mixture and salt at concentrations higher than 40 mM KCl, a different gelation behaviour was observed: a gel structure was already present at high temperature and a glass transition was measurable at the lowest temperatures. We believe this study gives new insights into the molecular state of carrageenan in the presence of high concentrations of sugars.  相似文献   

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《Food chemistry》1988,28(2):149-157
The levels of sucrose and α-galactosides of sucrose in a range of leguminous seeds extracted by various procedures and analysed by the gel-permeation technique are reported. Cowpeas contained the highest levels of α-galactosides, dry weight basis, the lowest levels being recorded in chickpeas. Levels in lupins are almost comparable with soybeans and intermediate quantities have been measured in adzuki beans. All the legumes examined contained varying amounts of α-galactoside-hydrolysing enzyme (α-galactosidase EC 3.2.1.22) and the defatting process has no effect on its activity. No hydrolysis of these oligomers due to the extraction technique has been observed, except in one procedure. Conditions of cultivation may have been responsible for anomalies in the values of these oligomers observed by various investigators within the same variety and species of a leguminous seed.  相似文献   

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The presence of residues of antimicrobial substances in milk may have serious toxicological and technical consequences. To date, few studies have been done to evaluate the effect of heat treatments on β-lactam residues in milk. However, the few studies that have been conducted estimate losses of antimicrobial activity under different combinations of temperature and time using microbiological methods. The aims of this study were to calculate the kinetic parameters for the degradation of β-lactam antibiotics in milk and to develop prediction models to estimate the concentration losses of these compounds in conventional dairy heat treatments. To do so, we employed a quantitative HPLC method to calculate losses in concentrations of 10 β-lactam antibiotics in milk with different combinations of temperature and time. Increasing the temperature from 60°C to 100°C decreased the half-life of amoxicillin (372 to 50 min), ampicillin (741 to 26 min), cloxacillin (367 to 46 min), and penicillin G (382 to 43 min). These increases in temperature caused further degradation in cephalosporins, which was accompanied by a decrease in half-life times to reach very low values; for instance, 4, 5, and 6 min for cefoperazone, cephurexime, and cephapirin, respectively. Kinetic equations were applied to different heat treatments used in dairy processing. Heat treatments at high temperatures and long times (e.g., 120°C for 20 min) led to a further degradation of β-lactam antibiotics with percentages close to 100% for cefoperazone and cefuroxime. In contrast, when milk was subjected to heat treatments at lower temperatures and times (e.g., 72°C for 15 s), the degradation of β-lactam in milk did not exceed 1% for the 10 antibiotics tested.  相似文献   

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Printing products are one kind of information carder.Printing can be seen as a service,serving almost all fields from politics, economy,military,science & technology,culture and education,news & publication,to daily life of the people.Every one of the people needs the services of printing.In China,with the development of market economy,printing has become increasingly important and more dependent to the economy.It is proper to say,the printing industry is growing simultaneously with the economy. So firstly I introduce some data about China's economy.  相似文献   

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AccordingtotheCustomsstatistics,thequantityofChina'simportedshoesin1997amountedto94.4665milionpairs,whichwerevaluedat358.3333...  相似文献   

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《Textile》2013,11(3):272-295
Abstract

Drawing on some observations by Anne Paul concerning the iconography of textile borders in cloth from archaeological sites in Paracas-Topará (southern Peru), and her suggestion that these acted as “markers of the sacred,” we examine some ethnographic contexts in highland Bolivia that also concern borders: the final moment of the wayñu dance each year, and the finishing of textile and field borders. In each case, we propose that the object is to control certain spirits believed to dwell within these borders, so that they finish their creative task there. Finally, we examine the relation between the so-called “war of the ayllus” in Bolivia (in 2000), which produced dramatic changes in regional aesthetics, and textile structures postwar, in which images from textile borders came to occupy the central space of woven cloth. We explain these changes through a theory concerning the war dynamics that occur between the borders and centers of modern territories in conflict, and the way that local populations understand these, which might also have archaeological significance in the case of Paracas-Topará.  相似文献   

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《Food chemistry》2001,75(1):1-27
Several molds, Aspergillus, Penicillium and to a lesser extent, Arthrinium can produce β-nitropropionic acid (NPA). The presence of NPA has been detected in at least four families of higher plants. Use of Aspergillus as an economic mould in the production of foods and the accidental contamination of foods provides for an historically lengthy and widespread exposure of humans to NPA. Despite widespread consumption of foods containing NPA, human poisoning by NPA is rare and confined to circumstances involving gross mishandling of the food products. NPA is absorbed in the gastrointestinal tract, enters the circulation and is metabolized to nitrite, although some may bind succinate dehydrogenase upon oxidation. The primary mechanism of toxicity of NPA is as a “suicide” substrate (non-competitive inhibitor) of succinate dehydrogenase, an enzyme of the mitochondrial membrane (part of Complex II) that catalyzes the oxidation of succinate to fumarate, which is manifested as pathological change in striatal areas of the brain. The physiological damage caused by NPA metabolic compromise resembles the genetic disorder, Huntington's disease. This resemblance has been extensively exploited in recent years to understand the mechanisms of neurodegeneration. There are no irreversible effects resulting from ingestion of subthreshold doses of NPA, nor is there any accumulation of NPA in the body. The LD50 dose of NPA for mice and rats is between 60 and 120 mg/kg. In long-term studies, NPA did not exhibit carcinogenicity or chronic toxicity. The reported no observed adverse effect level (NOAEL) for NPA is 2.5 and 3.75 mg/kg/day for male and female rats, respectively. Results of mutagenicity tests are mixed, but positive assays can be traced back to the use of a single impure sample of NPA. Based on the NOAEL of the chronic rodent bioassay, an ADI of 25 μg/kg/day or 1.750 mg/day for a 70 kg human is appropriate.  相似文献   

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A mathematical model of the steady-state sugar drying operation in a cross-flow rotating drum dryer is proposed. Although the model is based on the classic two-film concept of simultaneous heat and mass transfer, it also allows for the formation and growth of a thin layer of amorphous sugar due to local supersaturation of the sugar syrup. The formation of amorphous sugar is a result of the competition between crystallization and drying kinetics. The onset of amorphization is assumed to occur when the system moves from the metastable zone to the labile zone on the sucrose–water phase diagram. The rate of sucrose amorphization is controlled by the conditions prevailing on the metastability limit. Diffusivity of water through the amorphous sugar, the only adjustable parameter of the proposed model, has been determined by fitting sugar moisture data from an industrial Louvre-type dryer. The layer of amorphous sugar plays a critical role during the falling-rate period of drying. Generally, models ignoring its presence tend to overestimate the moisture removal rate. The presented model predicts a dramatic decline of the evaporation rate once the amorphous sugar begins to form which is observed in the industrial practice. The effect of key operating parameters such as air flow rate, hot air temperature, and crystal size on the dryer performance is also discussed.  相似文献   

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It is well known that wood species and particle size used influence the bending strength of three-layer particleboard. The objective of this study was to investigate the influence of using bagasse particles in surface layer on bending strength of three-layer particleboard panels. The ratio of the mixture of bagasse and wood particles was 3:7 and 4:6 in the surface and middle layers, respectively. Press temperatures were chosen at two levels of?165 and?180?°C. Three levels of urea formaldehyde resin were selected for the surface layers, namely: 8, 10, and 12?percent. Bending strength of the panels was determined according to the procedure of European Union (EN) Standard. The results show that bagasse has a positive effect on the bending strength of boards. In this research, the treatment with 40% bagasse and 12% resin in the surface layers and a?180?°C press temperature has resulted in an optimum bagasse board product.  相似文献   

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A fast, sensitive and reproducible method for the analysis of -tocopherol in pork tissues is presented. It combines saponification of the tissue and -tocopherol extraction in a single vessel, followed by HPLC separation and fluorescence detection. Added -tocopherol was recovered quantitatively. The reduction of lipid peroxides with potassium iodide before the saponification step did not alter the amounts of -tocopherol detected. Membranebound -tocopherol was not oxidized by lipid peroxides during the procedure. The coefficient of variation of -tocopherol analysed using this method was ±4.2% for muscle and ±2.5% for adipose tissues.
Methode zur schnellen Bestimmung von -Tocopherol in Muskel- und Fettgeweben des Schweines
Zusammenfassung Es wird eine schnelle, empfindliche und reproduzierbare Methode zur Bestimmung von -Tocopherol im Schweinefleisch vorgestellt. Die Methode verbindet die Verseifung des Gewebes und die Extraktion in einem Gefäß. Nach HPLC-Abtrennung wird das -Tocopherol mit einem Fluoreszenzdetektor bestimmt. Zugesetztes -Tocopherol wurde quantitativ wiedergefunden. Die Reduktion der Lipidperoxide mit Kaliumjodid vor der Verseifung hatte keinen Einfluß auf die im Gewebe bestimmten -Tocopherolgehalte. Das membrangebundene -Tocopherol wird während der Bestimmung nicht durch Lipidperoxide oxidiert. Der Variationskoeffizient der Methode lag für Muskelgewebe bei ±4,2% und für Fettgewebe bei ±2,5%.
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Liu H.  Li X.  Nurul H.R. 《丝绸》2021,(4):48-56
With the development of the methodology of research review, meta-analysis has been widely applied in the study of various disciplines.However, through literature collection and combing, it is found that the application of meta¬analysis in the field of domestic costume studies is still blank theoretically.To facilitate the extensive use of meta-analysis in domestic integration research on costume theories, and improve the standardization and objectivity of research on costume theories, through an analysis of the basic meaning, functions, advantages, sample selection and research process of meta¬analysis, 52 domestic research papers published from 2(K)7 to 2019 on the relationship between online consume reviews and consumers' purchase intention were taken as examples, to explore the application process of meta-analysis in the field of costume studies in a systematic way and key points thereof.Finally, through literature survey and an analysis of domestic and foreign applications, it is verified that meta-analysis has a good prospect in theoretical studies on costumes in the future. © 2021 China Silk Association. All rights reserved.  相似文献   

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The ability of α-keto acids to covert amino acids into Strecker aldehydes was investigated in an attempt to both identify new pathways for Strecker degradation, and analyse the role of α-keto acids as intermediate compounds in the formation of Strecker aldehydes by oxidised lipids. The results obtained indicated that phenylalanine was converted into phenylacetaldehyde to a significant extent by all α-keto acids assayed; glyoxylic acid being the most reactive α-keto acid for this reaction. It has been proposed that the reaction occurs by formation of an imine between the keto group of the α-keto acid, and the amino group of the amino acid. This then undergoes an electronic rearrangement with the loss of carbon dioxide to produce a new imine. This final imine is the origin of both the Strecker aldehyde and the amino acid from which the α-keto acid is derived. When glycine was incubated in the presence of 4,5-epoxy-2-decenal, the amino acid was converted into glyoxylic acid, and this α-keto acid was then able to convert phenylalanine into phenylacetaldehyde. All these results suggest that Strecker aldehydes can be produced by amino acid degradation initiated by different reactive carbonyl compounds, included those coming from amino acids and proteins. In addition, α-keto acids may act as intermediates for the Strecker degradation of amino acids by oxidised lipids.  相似文献   

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