Effects of Acid Treatment on Acid and Abrasion Resistance of Porcelain Enamels

The resistance of some enamels to attack by citric and other acids is improved by prior exposure to certain weak acids, which do not appreciably attack the enamel themselves. The abrasion resistance of some enamels is markedly decreased by exposure to citric acid for IS minutes at room temperature. These effects, as well as the results of some exploratory experiments on the nature and extent of these effects, are reported.     

Survival of pine sawflies in cocoon stage in relation to resin acid content of larval food

Several experiments were conducted to determine whether the ingestion of diterpenoids (resin acids) by pine sawfly larvae influences the survival of postlarval stages. Larvae of two diprionid sawfly species were reared on shoots of two Scots pine clones, one with a low (1.5% dry wt) concentration of resin acids and the other with a high (5.2% dry wt) concentration. No significant treatment-related differences were found in any of the experiments with respect to (1) resistance against parasitoids, (2) preference of predatory shrews and carabids, and (3) apparency of cocoons in the field to predators. A preference of sawfly prepupae to spin cocoon in feces from larvae reared on high resin acid needles was found. Possible explanations for these results are discussed. Detection of an unknown compound, possibly a breakdown product of the major resin acid in pine needles (pinifolic acid), in prepupae indicate that resin acids may be metabolized by the sawflies.     

Die Verdauung von Speisefetten mit Pankreaslipasen und ihre Beeinflussung durch das Fettsäuremuster

The Influence of Fatty Acids in Triglycerides on the Digestion of Dietary Fats by Pancreatic Lipase The digestion of dietary fats by pancreatic lipase was studied in in-vitro-experiments. We tested the following fats: coconut, butterfat, cocoabutter, lard and oil of corn germ. The breakdown of triglycerides was followed up by monitoring the free fatty acids and glycerol. Additionally we analyzed the fatty acid distribution by gas-liquid chromatography of triglycerides, 1,2-diglycerides and 2-monoglycerides. Fatty acids with a chain length from C₁₀C₂₀ were determined by gas chromatography. Short chain fatty acids were not regarded separately. As pancreatic lipase has a positional specificity for the 1- and 3-position of a triglyceride there is information on the distribution of fatty acids in fats and of their digestion by such experiments. For the resorption of the fatty acids it may be of a certain importance in which position it is esterified in the fat when it is hydrolysed in gut. The hydrolysis of fats used in these experiments was quite different. This can be explained by the fatty acid distribution, the chain length and by a varying rate of emulsification of fats in an aqueous phase.     

Cholesterol esters of milk and mammary tissue

The fatty acid composition and metabolic activity of cholesterol esters in milk and mammary tissue (cow, sow and goat) were investigated. Cholesterol esters of freshly secreted milks incubated at 40 C for 2 hr showed no change in fatty acid composition and no incorporation of 1-¹⁴C-palmitate. The fatty acid composition of cholesterol esters in the milk of all three species exhibited elevated levels of a unique group of fatty acids when compared to other milk ester lipid classes. This group was comprised of monounsaturated acids and acids with odd numbers of carbons. Tissue cholesterol esters contained lower levels of these acids. Evidence from experiments in which an odd carbon acid (C₁₅) was infused into the lactating mammary gland indicated that the group of unique acids is preferentially retained in the cholesterol ester fraction which is secreted with milk. These infusion experiments also provided evidence that cholesterol esters accumulate in developing milk fat globules in a manner paralleling triglyceride accumulation, and that acyl moieties of cholesterol esters may be desaturated in the form of the intact ester. Our results are compatible with the hypothesis that acyl moieties of cholesterol esters in lactating mammary tissue are turning over rapidly. Paper No. 3496 in the journal series of the Pennsylvania Agricultural Experiment Station.     

Hydrogenation of cyclopropenoid fatty acids occurring in cottonseed oil

The hydrogenation of cyclopropenoid acids and their relative reactivities during hydrogenation as compared to linoleic and oleic acids were examined. Pure methyl sterculate and purifiedSterculia foetida oil and its methyl esters, which have a cyclopropene content more than 60 times that of cottonseed oil, were used for the hydrogenation experiments. Nickel, palladium and platinum catalysts were used. The effect of temperature and type of catalyst were demonstrated in a series of hydrogenation experiments of safflower andS. foetida oil mixtures, and methyl oleate and methyl dihydrosterculate mixtures. Partial hydrogenation of methyl sterculate formed as many as twenty compounds in addition to the cyclopropenoid derivatives. Most of these compounds were monounsaturated. The cyclopropene group hydrogenated very readily compared to the 9,12-diene system in linoleate. The cyclopropane group obtained by hydrogenating the cyclopropenoid acids group was quite resistant to further attack by hydrogen and nickel catalyst had little effect. With palladium catalyst, a temperature of 180 C was necessary for the reaction to go to completion. Platinum in acetic acid was a good system for hydrogenolysis of the cyclopropane group at 80 C. Retired.     

Effects of additives on fire properties of polyethylene

Low-density polyethylene, with and without an antimony–bromine synergistic fire retardant or aluminium hydroxide, was subjected to standard fire tests and to experiments which determined the smoke and harmful fumes emitted on overheating. Both additives improved most fire properties but the fire retardant increased the smoke generated by intense radiant heat. The onset of smoke, flammable gas, carbon monoxide and acids was generally delayed by the additives. The total amounts and maximum values of these volatiles were lessened. Sample weight and form affect the results of these experiments. Observations during heating show that the additives reduce spreading of the melt, thus reducing the surface area available for oxidation.     

Identification of straight-chain fatty acids in coal extracts and their geochemical relation with straight-chain alkanes

Mono-carboxylic, straight-chain fatty acids are present in extracts of lignite and subbituminous coal (0.4–1.0 wt%, daf basis), but not in those of a bituminous coal. They are removed with nearly equal ease by both solvent and supercritical gas (SCG) extraction. Octacosanoic acid is the major constituent, and values of the carbon preference index (even over odd) lie between 2 and 6. Solvent extraction of the coals also removes small quantities (< 0.08 wt%) of straight-chain alkanes which are closely related in composition to the straight-chain fatty acids and are probably derived from them during maturation. However, previous SCG extraction of the coals yielded much larger quantities of straight-chain alkanes (0.3–0.7 wt%). Pyrolysis experiments with a lignite fatty acid fraction and with tetracosanoic acid show that these acids largely survive SCG extraction and, therefore, are not the main source of the relatively large quantity of straight-chain alkanes in these extracts.     

Influence of various catalyst poisons and other impurities on fatty acid hydrogenation

The effect of various impurities which reduce the activity of nickel catalysts during fatty acid hydrogenation has been studied. It is here proposed to divide the compounds which negatively influence the nickel-based fatty acid hydrogenation process into three categories, namely, catalyst poisons, inhibitors and deactivators, each group acting according to a different mechanis. The deleterious effect of typical catalyst poisons, such as S, N, P or Cl, is more or less independent of the chemical nature of the individual organic compounds containing these elements. There is good correlation between these element contents and the required nickel catalyst loading level. Other typical impurities present in technical fatty acids, such as oxidized fatty acids, soaps and water, also diminish the catalyst activity considerably. A number of experiments were designed to study the influence of various pretreatments of fatty acids on the catalyst loading levels needed for hydrogenation. In view of the high cost of nickel catalysts, considerable savings can be obtained by pretreatment of fatty acids prior to hydrogenation. Such pretreatment steps may include sulfuric acid washing, application of spent catalysts, and/or distillation. The most economical method will depend on local circumstances.     

亚马逊莓（Euterpe oleracea）美白相关成分和作用研究现状

作为棕榈科植物Euterpe属中分布最为广泛、研究与商业化程度最高的品种，Euterpe oleracea（E. oleracea）的果实（为亚马逊莓的一种）因其卓越的抗氧化性能而跻身“超级水果”之列，同时也成为国际上新的研究热点。本文综述了E. oleracea的相关成分和作用研究现状，指出其富含不饱和脂肪酸、氨基酸、维生素等营养成分，并含有大量的以酚类化合物为主的生物活性物质，例如黄酮类化合物、酚酸、花青素与原花青素等。其中，总脂肪酸、亚油酸、阿魏酸、槲皮素、原儿茶酸、原儿茶酸甲酯等成分被证实具有皮肤美白作用。对E. oleracea进行的细胞实验和动物实验发现，其果肉提取物具有抑制酪氨酸酶活性以及使细胞免受紫外线引起的氧化应激伤害等潜在的皮肤美白功效。文章建议在未来的研究中，对E. oleracea的美白成分进行进一步挖掘，并通过动物实验与临床试验对其美白功效进行验证。     

The Role of Momilactones in Rice Allelopathy

Large field screening programs and laboratory experiments in many countries have indicated that rice is allelopathic and releases allelochemical(s) into its environment. A number of compounds, such as phenolic acids, fatty acids, phenylalkanoic acids, hydroxamic acids, terpenes, and indoles, have been identified as potential rice allelochemicals. However, the studies reviewed here demonstrate that the labdane-related diterpenoid momilactones are the most important, with momilactone B playing a particularly critical role. Rice plants secrete momilactone B from their roots into the neighboring environments over their entire life cycle at phytotoxic levels, and momilactone B seems to account for the majority of the observed rice allelopathy. In addition, genetic studies have shown that selective removal of the momilactones only from the complex mixture found in rice root exudates significantly reduces allelopathy, demonstrating that these serve as allelochemicals, the importance of which is reflected in the presence of a dedicated momilactone biosynthetic gene cluster in the rice genome.     

The effect of temperature on the in vitro formation of methyl esters in mouse liver

The appearance of methyl esters of fatty acids in lipid extracts was studied. Experimental evidence indicates that these esters are both natural components of tissues as well as products of technical manipulation. Effect of temperature on the latter process was studied. The results of these experiments show that the post-mortem increase of fatty acid methyl esters could best be explained by postulating an enzymatic rather than a chemical process.     

超强酸在有机合成中的应用研究

无机酸较超强酸相比,更早地投入到了实验中,并且应用范围也相当广泛,但对于相对复杂甚至难以进行的一些有机反应,超强酸就发挥了不可小觑的催化作用。主要介绍超强酸的定义、性质以及超强酸在有机合成反应中的应用。     

Behavior of amino acid production from hydrothermal treatment of fish-derived wastes

The effect of operating parameters (temperature and time) and various reaction modes(batch, semi-batch and continuous flow) on the behavior of amino acid production from hydrothermal decomposition of fish-derived wastes was investigated. The amino acids obtained in batch experiments at 523 K were mainly alanine (Ala) and glycine (Gly) at maximum yield of 65 and 28 mg/g-dry fish, respectively. At a relatively lower temperature of 473 K, the relative concentration of high-molecular-weight amino acids such as aspartic acid (Asp) and serine (Ser) is significantly high, but decreases as temperature increases. It is likely that high-molecular-weight amino acids decompose faster than low-molecular ones. Semi-batch and continuous flow modes of reaction suppressed decomposition of amino acids into organic acids (or volatile materials) by continuously removing the products from the reaction zone as soon as they were formed. Thus, a large amount of high-molecular-weight amino acids such as Asp and Ser at these reaction modes was observed. This increases the yield of total amino acids at short reaction time and at temperature relatively higher than 523 K. It was also observed that the composition of the resulting products also depends on the modes of reaction.     

Chemical-Shift Perturbations Reflect Bile Acid Binding to Norovirus Coat Protein: Recognition Comes in Different Flavors

Bile acids have been reported as important cofactors promoting human and murine norovirus (NoV) infections in cell culture. The underlying mechanisms are not resolved. Through the use of chemical shift perturbation (CSP) NMR experiments, we identified a low-affinity bile acid binding site of a human GII.4 NoV strain. Long-timescale MD simulations reveal the formation of a ligand-accessible binding pocket of flexible shape, allowing the formation of stable viral coat protein–bile acid complexes in agreement with experimental CSP data. CSP NMR experiments also show that this mode of bile acid binding has a minor influence on the binding of histo-blood group antigens and vice versa. STD NMR experiments probing the binding of bile acids to virus-like particles of seven different strains suggest that low-affinity bile acid binding is a common feature of human NoV and should therefore be important for understanding the role of bile acids as cofactors in NoV infection.     

Fatty acid composition of liver lipids during development of rat

The fatty acid composition of triglycerides and phospholipids from rat liver was determined throughout the period of growth in the rat. Major changes in the triglyceride fatty acid composition were observed during the period studied. The triglycerides from fetal and newborn rats contained only a small percentage of polyunsaturated acids compared with suckling and weanling rats. During the suckling phase the liver triglycerides were rich in long chain polyunsaturated acids such as 20∶4, 20∶5, 22∶5, and 22∶6; once the pups were weaned, the percentage of these acids in the liver triglycerides fell. In these experiments, 18∶2 and 18∶3 were the only polyunsaturated acids in the maternal diet. However, the stomach contents of the suckling pups contained 18∶2 and 18∶3, as well as the long chain polyunsaturated acids. Radioactive 18∶3 and 22∶6 were fed to suckling pups, and the results suggested that the LCP in the rat liver triglycerides during the suckling period were derived from the long chain polyunsaturated acids in the dam's milk, rather than by synthesis from either 18∶2 or 18∶3 within the pups.     

A Continuous Process for the Purification of Terpenyl Amines Using a Reversible Acid‐Base Reaction

The reversible reactive extraction of long‐chain terpenyl amines (TPAs) using organic acids as reactive extractants was investigated. The scope of suitable acids has been extended and semicontinuous and continuous experiments were performed to prove the applicability of this concept. High extraction yields could be achieved using a variety of acids in batch and semicontinuous experiments. Furthermore, the recovery and separation of the extracted TPAs from the extractant phase has been studied. The TPAs can be recovered in high yields and purities by simple means of process parameter changes. The proposed process allows the separation and purification of TPAs in high yields and purities without the creation of salts or other chemical by‐products.     

Separation of zirconium from hafnium by ion exchange

This work aimed at separating Zr(IV) from Hf(IV) from an acid solution using cationic resin through column experiments. The influence of different inorganic acids in the loading of the resin as well as different organic and inorganic eluents such as hydrochloric, sulfuric, citric and oxalic acids were evaluated. The loading of Zr varied from 1.14 to 1.26 mmol g^?1 and for Hf it varied from 0.041 to 0.140 mmol g^?1. Elution with 0.5 M oxalic acid was the best option for the separation of these elements. The elution removed 100% of the Zr and 70% of the Hf. The final product contains 1% Hf and 99% Zr.     

Kairomones and their use for management of entomophagous insects. XV.

Acids found in moth scales of laboratory-rearedHeliothis zea (Boddie) moths are hexanoic, heptanoic, octanoic, nonanoic, 2- (or 3-) furan carboxylic, phenylacetic, benzoic, sorbic, and 4-hydroxybenzoic acid. The last two of these acids are preservatives added to the artifical diet as sorbic acid and methyl-p-hydroxybenzoate. FemaleTrichogramma pretiosum Riley exhibited increased rates of parasitization ofH. zea eggs in the presence of some of these compounds in laboratory experiments. Exposure to a mixture of all of these compounds did not increase parasitization, and the elimination of acids from the crude moth-scale extract did not reduce parasitization by the wasps.Lepidoptera: Noctuidae.Hymenoptera: Trichogrammatidae.In cooperation with the University of Georgia College of Agriculture Experiment Stations, Coastal Plain Station, Tifton, Georgia 31793.Mention of a commercial or proprietary product in this paper does not constitute endorsement by the USDA.     

水溶性弛豫试剂在醇、酸、胺体系中的定量研究

在核磁共振实验中,13C核弛豫慢,利用核磁共振13C谱对应用体系中的碳核进行定量分析需要耗费大量的实验时间,通常需要在体系中加入顺磁性弛豫试剂,可以有效提高'3C核的弛豫速率,缩短实验时间.开发了EDTA-Cu作为弛豫试剂,分别应用于不同类型的水溶性样品,研究结果表明EDTA-Cu配合物浓度为0.03～0.04mol/...     

寡聚酸合铁（Ⅲ）制备工艺的研究

以寡聚酸和三氯化铁为原料,研究了不同的反应体系pH值和配位比对寡聚酸合铁（Ⅲ）合成及其水解稳定性的影响,并且用红外光谱分析对寡聚酸合铁（Ⅲ）的结构进行了表征。试验结果表明：经过单因素试验,确定出反应的最佳pH值为6,最佳配位比为：寡聚酸／铁＝1：16。将纯化后的产品做红外光谱分析,并和纯品寡聚酸的红外光谱做了比较,证明寡聚酸合铁（Ⅲ）成螯合状态。