Determination of acid values of fats and oils by flow injection analysis with electrochemical detection

A new method using a flow injection system with electrochemical detection was developed to determine acid values of fats and oils. VK3 (2-methyl-1,4-naphthoquinone) solution, i.e., ethanol containing 3 mM VK3 and 38 mM LiClO4, was used as the carrier solution. Flow signals were monitored at -0.33 V vs. Ag/AgCl. For preparation of a sample solution, an oil sample was completely dissolved in VK3 solution, or fatty acids were extracted from the sample into this solution. Aliquots (5 microliters) of the sample solution were injected into the flow injection system. Acid values were determined based on flow signals for 14 samples and the results were found to be consistent with those by potentiometric titration. Relative standard deviation was less than 2%. Samples were processed at the rate of 60 h-1. The stability of fish and cod liver oils was followed by measuring acid values for 8 weeks. This method proved to be a simple and rapid means for acid value determination.     

Self-propagating high-temperature synthesis in the production of functional coatings

The direct synthesis of refractory compounds and the reduction of metal oxides by self-propagating high-temperature synthesis are subjected to thermodynamic analysis. The laws of self-propagating high-temperature synthesis are investigated, and the possibility of creating functional metal-oxide coatings of specified composition by that means is considered.     

Inhibition of growth and aflatoxin production of Aspergillus parasiticus by citrus oils

Aspergillus parasiticus was inoculated into grapefruit juice and a glucose-yeast extract medium; both contained 500-7000 ppm of citrus oils that were incorporated into the media by sonication. Orange and lemon oil were more inhibitory to mold growth and aflatoxin production than was dlimonene, the main constituent of the two peel oils. After 7 days at 28 degrees C, 2000 ppm of lemon and 3000 ppm of orange oil in grapefruit juice afforded maximum suppression of mold growth and toxin formation. When the glucose-yeast extract medium was used, 3000 ppm of either oil were needed to achieve the same result. After 4 days at 28 degrees C, orange oil at 3500 ppm in either medium markedly inhibited mold growth (as evidenced by dry weight of mold mycelium) and aflatoxin production (only 14 and 1% of the amount normally produced in the juice and artificial medium, respectively). Higher concentrations of orange oil further reduced mold growth and aflatoxin production and also delayed the onset of sporulation, if it occurred. Although aflatoxin was detected in all samples, only 0.2 to 0.5% of the amount found in controls (without the citrus oil) was present when the medium contained 7000 ppm orange oil. The mold consistently grew, albeit very poorly, on the glass at the liquid-atmosphere interface even when the substrate contained a large amount of citrus oil.     

Site of digestion and milk production by cows fed fats differing in saturation, esterification, and chain length

Four cannulated cows in a 4 x 4 Latin square design were used to study the effects of supplemental dietary fatty acids from roasted soybeans combined with tallow or partially hydrogenated fats, varying in esterification and fatty acid chain length, on nutrient digestion and lactation performance. Diets were formulated to contain (DM basis) 48% forage in addition to 1.5% fatty acids from roasted soybeans and 2.5% fatty acids from tallow, partially hydrogenated tallow triglycerides, partially hydrogenated tallow fatty acids, or a blend of 30% tallow and 70% hydrogenated fatty acids that were rich in palmitic acid. Apparent total tract digestibilities of OM, N, and NDF were similar among diets. Supplemental fat as fatty acids, compared with triglycerides, increased digestibilities of total fatty acids and C18:1 in the small intestine, perhaps indicating that lipolysis was rate-limiting. Fatty acids also increased milk fat percentage and efficiency of 4% FCM production. Although intake of C16 fatty acids was higher for cows fed the fat rich in palmitic acid than for those fed the tallow fatty acids, total duodenal flows of C16 fatty acids were similar, and digestibility in the small intestine was unaffected. Dry matter intake, 4% FCM production, and milk protein percentage were similar among treatments.     

Mortality and production characteristics of laying chickens fed high- and low-erucic acid rapeseed oils

Laying pullets were fed a diet supplemented with three percent of either high-erucic acid rapeseed (HEAR) oil or low-erucic acid rapeseed (LEAR) oil for 39 weeks. Egg production for the period was 78.8 and 80.1% by the birds fed the respective oils. Average egg weights were 56.8 and 58.7 g. respectively. Gains in body weight, liver weight and adrenal gland weight were similar with the two types of oil fed. Feed consumption was similar for the two groups of birds. The efficiency of utilization of the diet containing HEAR oil was accordingly lower than that of the diet containing LEAR oil. In the birds fed HEAR and LEAR oil respectively mortality attributed to metabolic disorders of the reproductive system, liver, and kidney was 3.3% and 1.2%. Mortality from other causes in the birds fed the two oils was 3.2 and 3.8% of the original populations.     

Recent advances of cerium compounds in functional coatings:Principle,strategies and applications

Cerium(Ce) compounds have attracted considerable attention as key components in functional coatings due to their many outstanding properties.This work provides a comprehensive review of recent advances in the application of Ce in functional coatings.The role of Ce in the improvement of functional properties such as corrosion-resistance,self-healing,superhydrophobicity,wear-resistance,and UV shielding is reviewed from the perspective of functional mechanism and applied research.Furthermore,the strategies,processes,practical problems,and current challenges in the research of functional coatings containing Ce are summarized and discussed.The objective is to highlight the great potential of Ce in functional coatings,and to explore new applications of Ce in the development of novel coatings.Thus,this work aims to enhance the application value of Ce,solving the problem of unbalanced application of rare-earth elements.     

Interactions among iron, calcium, phosphorus and magnesium in the nutritionally iron-deficient rat

We studied the development of nutritional iron deficiency 0, 10, 20, 30 and 40 days after the intake of a semisynthetic diet lacking iron (diet 0) and the possible interactions with calcium, phosphorus and magnesium in both control rats and rats after 40 days of iron deficiency. During this period, iron deficiency was found to produce stress in the rats, as evidenced by high levels of cortisol in the serum. High levels of parathyroid hormone (PTH) were also found. There was a considerable increase in the absorption of calcium, phosphorus and magnesium, but the phosphorus and magnesium balance decreased and that of calcium remained practically unchanged, although there was an increase in calcium urinary elimination. Despite the noticeable degree of bone demineralization, which was evident in the femur, serum levels of calcium, phosphorus and magnesium remained constant. The present study shows that severe nutritional ferropenic anaemia provokes significant alterations in the metabolism of calcium, phosphorus and magnesium. We conclude that these alterations should be taken into account in the treatment of this pathology, given its prevalence and the fact that it may exacerbate other pathologies, particularly those related to the metabolism of calcium and phosphorus.     

Assessing adolescent interpersonal negotiation strategies: Toward the integration of structural and functional models.

In a structured dilemma-discussion interview procedure, 45 female and 45 male middle-class adolescents (aged 11–19 yrs) were presented with 8 hypothetical dyadic interpersonal dilemmas to assess the interpersonal negotiation strategies (INS) they suggested using to resolve interpersonal problems. Each dilemma focused on the way a protagonist could deal with a significant other in a dyadic context. Responses were scored using an integrated structural developmental (4 levels) by functional (4 information processes) model of social-cognitive development. In addition, the 8-dilemmas were constructed to systematically vary with respect to 3 contextual factors. Results indicate that (1) INS showed a developmental increase over the adolescent years, (2) INS showed a moderate positive relation to IQ, (3) the INS level was higher for girls than for boys, and (4) INS level systematically varied across context. The findings provide preliminary evidence for the validity of the INS interview. The INS interview is appended. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Protein carbonyl content roughly reflects the unsaturation of lipids in muscle but not in other tissues of stroke-prone spontaneously hypertensive strain (SHRSP) rats fed different fats and oils

We examined in vivo the effect of dietary fats and oils with different peroxidizability on protein carbonyl content, the presumed index of free radical-mediated protein oxidation. For 15.6 months, SHRSP (stroke-prone spontaneously hypertensive strain) rats were fed a diet supplemented with lard, safflower oil, perilla oil or fish oil/soybean oil, the peroxidizability of which increases in this order. The peroxidizability of tissue lipids was positively correlated with the protein carbonyl content in skeletal muscle, but not in the brain, heart or liver. The protein carbonyl content in the lard group was higher in the brain and liver compared to the other dietary groups. These results contradict the concept that long-term feeding of easily autoxidizable fatty acids allows the accumulation of lipid peroxides to accelerate the development of the free radical diseases, and suggest that tissue protein carbonyl content is not a simple reflection of autoxidizability-related lipid peroxidation but is also influenced by other biochemical processes.     

A functional requirement for modification of the wobble nucleotide in tha anticodon of a T4 suppressor tRNA

Temperature-sensitive mutants of E. coli have been isolated which restrict the growth of strains of bacteriophage T4 which are dependent upon the function of a T4-coded amber or ochre suppressor transfer RNA. One such mutant restricts the growth of certain ochre but not amber suppressor-requiring phage. Analysis of the T4 tRNAs synthesized in this host revealed that many nucleotide modifications are significantly reduced. The modifications most strongly affected are located in the anticodon regions of the tRNA'S. The T4 ochre suppressor tRNAs normally contain a modified U residue in the wobble position of the anticodon; it has been possible to correlate tha absence of this specific modification in the mutant host with the restriction of suppressor activity. Furthermore, the extent of this restriction varies dramatically with the site of the nonsense codon, indicating that the modification requirement is strongly influenced by the local context of the mRNA. An analysis of spontaneous revertants of the E. coli ts mutant indicates that temperature sensitivity, restriction of phage suppressor function, and undermodification of tRNA are the consequences of a single genetic lesion. The isolation of a class of partial revertants to temperature insensitivity which have simultaneously become sensitive to streptomycin suggests that the translational requirement for the anticodon modification can be partially overcome by a change in the structure of the ribosome.     

Corandomization of fats improves absorption in rats

Human milk fat is well absorbed despite its large concentration of long-chain saturated fatty acids (LCSFA), particularly palmitic acid. The superior absorption has been ascribed in part to the uncommonly high proportion of the palmitic acid in the sn-2 position of the triglycerides, 70% in human milk triglycerides compared with 10-15% in the fats and oils commonly used in infant formula blends. Colipase-dependent pancreatic lipase selectively hydrolyzes the fatty acids at the sn-1 and 3 positions, yielding free fatty acids and the 2-monoglyceride, which are absorbable. Free palmitic acid, but not monopalmitin, can be lost as calcium soaps in the feces. The present study demonstrated that mixtures of coconut oil and palm olein are better absorbed by rats if the proportion of LCSFA in the sn-2 position is increased by the process of chemical randomization, in which the fatty acids of the native oils are redistributed equally to all three positions in the rearranged triglycerides. The fecal excretion of total fatty acids, essentially LCSFA, from the mixtures in which the oils were randomized together (corandomized) was 30 to 60% less than from the mixtures of native oils.     

Changes in ovarian function and gonadotropin secretion preceding the onset of nutritionally induced anestrus in Bos indicus heifers

The aim of this study was to monitor endocrine and ovarian changes immediately preceding the onset of nutritionally induced anestrus. Daily blood samples were obtained from 14 postpubertal heifers for one estrous cycle (initial estrous cycle). Subsequently, heifers designated "restricted" were given a limited diet (n = 9), and daily blood samples were obtained for approximately 21 days preceding onset of anestrus (anovulatory cycle). Controls were allowed ad libitum dietary intake (n = 5), and daily blood samples were collected for a complete estrous cycle during a time period that coincided with that preceding onset of anestrus in restricted heifers. Plasma samples were assayed for LH, FSH, progesterone, and estradiol-17 beta. The ovaries of all heifers were examined daily using transrectal ultrasonography from the initial until the final or anovulatory estrous cycles to determine changes in growth of follicles and corpora lutea. Anestrus was defined as failure of ovulation of the dominant follicle following luteolysis. When anovulatory and initial estrous cycles in restricted heifers were compared, mean concentrations of LH were lower (p < 0.01), and diameters of dominant follicles were smaller (p < 0.01); mean concentrations of estradiol-17 beta were also lower in the three days following luteolysis (p = 0.06), but concentrations of FSH appeared to be higher (p = 0.003); maximum diameters of corpora lutea were smaller (p < 0.001), but duration of luteal phases and concentrations of progesterone preceding luteolysis were similar (p > 0.10). In controls, no differences were found between estrous cycles for any of these variables. It is concluded that failure of ovulation, following reduced dietary intake, resulted from insufficient circulating LH to stimulate maturation of the ovulatory follicle.     

The post-translational modification in cytochrome c oxidase is required to establish a functional environment of the catalytic site

Mutation of tyrosine-288 to a phenylalanine in cytochrome c oxidase from Rhodobacter sphaeroides drastically alters its properties. Tyr-288 lies in the CuB-cytochrome a3 binuclear catalytic site and forms a hydrogen bond with the hydroxy group on the farnesyl side chain of the heme. In addition, through a post-translational modification, Y288 is covalently linked to one of the histidine ligands that is coordinated to CuB. In the Y288F mutant enzyme, the "as-isolated" preparation is a mixture of reduced cytochrome a and oxidized cytochrome a3. The cytochrome a3 heme, which is largely six-coordinate low-spin in both oxidation states of the mutant, cannot be reduced by cytochrome c, but only by dithionite, possibly due to a large decrease in its reduction potential. It is postulated that the Y288F mutation prevents the post-translational modification from occurring. As a consequence, the catalytic site becomes disrupted. Thus, one role of the post-translational modification is to stabilize the functional catalytic site by maintaining the correct ligands on CuB, thereby preventing nonfunctional ligands from coordinating to the heme.     

氧化铝生产中四蒸发减温减压系统的改造实践

四蒸发减温减压是某公司氧化铝分厂第3蒸发站和第4蒸发站使用蒸汽压力和温度调节的重要生产工序.本文介绍了采用直行程减温减压阀、机械密封和变频调速装置来控制减温水加入量的方法来改进减温减压的成功经验.     

Residues of perchlorethylene and petroleum in rendered fats and in feeding meals

Methods were developed for the demonstration and determination of perchlorethylene and petrol in rendered fats and meals for feeding purposes. The methods are based on the collection and the vapours of extracting media over samples of rendering-plant products and on their identification and determination by gas chromatography. Under the conditions of the method, the limit of perchlorethylene extractibility is 0.05% and the limit of petrol extractibility is 0.01% (weight). Under adapted conditions the two limits can be reduced. The reproducibility of the results at practically occuring concentrations of residues in products is characterized by the value of the variation coefficient which reaches 2.79 in perchlorethylene and 6.05 in petrol. The maximum duration of the analysis of one sample is five minutes. In all media have been demonstrated to be present. Their content was high and considerably variable in the fats from rendering plants; in meat-bone meals from petrol extraction the content of residues reached only trace values. It is recommended to use the presented analytic methods for thorough and regular objective control of the residues of extracting media in the products of rendering plants for feeding purposes.     

Evidence for production and functional activity of nitric oxide in seminiferous tubules and blood vessels of the human testis

Previous studies have demonstrated that nitric oxide (NO) influences Leydig cell function. Here we provide evidence for NO production and activity in seminiferous tubules and blood vessels of the human testis. By immunohistochemistry, the soluble guanylyl cyclase (sGC), the intracellular NO receptor, and the second messenger, cyclic guanosine monophosphate (cGMP), were detected in myofibroblasts of the peritubular lamina propria in Sertoli cells, as well as in endothelial and smooth muscle cells of testicular blood vessels. Performed with isolated tubules and blood vessels, the biological activity of sGC could be proved by cGMP generation in response to treatments with the NO donor, sodium nitroprusside. The endothelial and neuronal subtypes of NO synthase (NOS) were localized immunohistochemically to the same cell types that express sGC and cGMP. In isolated tubules and vessels, the presence of endothelial NOS and neuronal NOS was confirmed by immunoblotting, and NOS activity was demonstrated by decreased cGMP production upon incubation with the NOS inhibitor L-nitro arginine methylester. These findings show that peritubular cells, Sertoli cells, and testicular blood vessels may be sites of NO production and activity, possibly involved in relaxation of seminiferous tubules and blood vessels to modulate sperm transport and testicular blood flow, respectively.     

Influence of dietary fats upon systolic blood pressure in the rat

Studies were performed to determine whether feeding diets with differing fatty acid content and composition had an influence on systolic blood pressure in the rat. Weanling male rats were fed standard laboratory chow (2.9% fat in total), or synthetic diets (10% fat in total) containing fish oil, butter, coconut oil or corn oil, for 5 weeks. Coconut oil and butter diets were rich in saturated fatty acids, whilst fish oil and corn oil were rich in the n-3 and n-6 unsaturated fatty acids respectively. Systolic blood pressure was measured using an indirect tail-cuff method at the end of the feeding period, and compared to a group of weanling rats. Feeding the different diets did not alter the growth of the rats, so all animals were of similar weights at the time of blood pressure determination. Control (chow fed) animals, at nine weeks of age, had higher systolic blood pressures than the weanling, baseline control group. Fish oil fed rats had similar pressures to the chow fed rats. Corn oil fed rats had significantly lower systolic pressures than the controls. The rats led the diets rich in saturated fatty acids (butter and coconut oil) had significantly higher blood pressures than all other groups. Systolic blood pressure was found to be significantly related to the dietary intakes of saturated and unsaturated fatty acids. The dietary intake of linoleic acid was significantly higher in corn oil fed rats than in other groups. Systolic blood pressure was inversely related to linoleic acid intake. Feeding a diet rich in saturated fatty acids significantly increases blood pressure in the rat. A high intake of n-6 fatty acids, and in particular linoleic acid, appears to have a hypotensive effect. Prenatal exposure of the rats to a maternal low protein diet, abolished the hypertensive effects of the coconut oil diet and the hypotensive effect of the corn oil diet upon young adult females. The intrauterine environment may, therefore, be an important determinant of the effects of these fatty acids on blood pressure in later life.