Endotoxin-induced platelet aggregation in heparinised equine whole blood in vitro

Endotoxaemia is a leading cause of death among horses. Thrombocytopenia is a common finding in clinical and experimentally-induced cases of endotoxaemia and can lead to coagulopathies, including disseminated intravascular coagulopathy which is usually fatal. In this study it was shown that endotoxin (3 ng ml-1 to 25 micrograms ml-1) can aggregate equine platelets in heparinised whole blood in vitro. The endotoxin-induced aggregation (EIA) was shown to be dependent on the presence of leucocytes in the blood and did not occur when detoxified endotoxin was used, suggesting that lipid A was necessary for the response. Aspirin (1 mmol litre-1) had no effect on EIA whereas apyrase (40 micrograms ml-1) completely abolished it and CV3988 (3 to 30 mumol litre-1) (a competitive antagonist of platelet-activating factor) inhibited the response in a concentration-dependent manner. It is concluded that endotoxin activates equine platelets at low concentrations through an indirect mechanism that involves calcium, leucocytes, adenine nucleotides and platelet-activating factor.     

Mechanical performance of ceramic matrix composite I-beams

Experimental studies have been performed on ceramic matrix composite (CMC) I-sections, which typify joint designs for CMC components. Axial loads and moments have been applied to activate delamination mechanisms. The maximum load bearing capacity has large variability, governed by the severity of manufacturing flaws located in the transition region of the I-section. This variability leads to an unsatisfactory design situation. Delaminations that form from these flaws arrest and behave in a stable manner, subject to a remanent load bearing capacity. This remanent capacity has minimal variability. Hence, design based on the remanent load would be robust. An expression for this design criterion is presented.     

The relationship between isometric strength of Cantonese males and the US NIOSH guide for manual lifting

A laboratory study was undertaken to assess the relationship between the maximal voluntary isometric strength (MVIS) of a group of Hong Kong Cantonese males and recommended limiting values for lifting proposed in the Work Practices Guide for Manual Lifting (NIOSH, 1981). Forty-one male subjects were required to apply a 'free-style' vertical 'lift' force to a horizontal bar located 150 mm from the ground. Forces were applied with the horizontal location of the midpoint of the ankles at 200, 400, 600 and 800 mm from the bar. The results were compared with the Maximal Permissible Limit (MPL) and the Action Limit (AL) values proposed in the NIOSH guide. The results showed that the mean MVIS of the Hong Kong subjects lay between the MPL and AL when the load was 200 mm and 400 mm from the ankles, but was significantly below the AL at 600 mm. At 800 mm more than half of the subjects were unable to apply any measurable positive vertical force. The compressive force at the L5/S1 disc of four subjects was estimated using a static biomechanical model. The relationship between the disc pressure and the force exerted was largely in accordance with NIOSH guide values. The results are discussed in terms of differences in subject population and lifting technique. Comments on the applicability of the NIOSH standards internationally, are also presented.     

Characterizing the interface of nickel-zincate-aluminum thin films

The manufacture of plated computer memory disks requires a complex sequence of processing steps. One of the most important factors affecting disk surface topography and adhesion between nickel and aluminum was found to be the formation and diffusion of a zincate thin film at the nickel-aluminum interface. To improve the adhesion, the strength of the weak link (the zinc layer) must be increased. This can be accomplished by alloying the zinc layer with the aluminum and nickel layers by co-diffusion, which is accelerated at high temperatures, or by keeping the zinc layer very thin. Surface topography can be modified by changing the metallurgical properties of the substrate, promoting the diffusion of elements between layers at elevated temperatures, or adjusting the zincating bath parameters.

     

Evaluation of tempering induced changes in the hardness profile of case-carburised EN36 steel using magnetic Barkhausen noise analysis

The effect of tempering on the magnetic Barkhausen noise (MBN) signal profile was studied in case-carburised EN36 steel using a range of magnetic excitation frequencies and a number of frequency ranges for analysis of the MBN signal. The MBN level generally increases with tempering due to coarsening of the microstructure. With higher values of excitation frequency, f_EX, the MBN profile exhibits a single peak, but with low values of f_EX, double peaks are observed. The MBN peak obtained with higher f_EX was found to correlate well with hardness changes in a region, down to 100 μm below the surface. The analysis of the MBN signal produced with low f_EX, in narrow frequency ranges selected by software frequency filtering, showed variations in the extent of changes in the relative height of the two MBN peaks in the profile. After taking into account the skin depth-frequency relation for the MBN signal, variations in the values of the two MBN peaks in different analysing frequency ranges were found to correlate well with hardness variations at different depths down to 425 μm below the surface. An empirical relationship has been established between the hardness-depth profile and the MBN measurements.     

The mechanical properties of nickel oxide and their relationship to the morphology of thick oxide scales formed on nickel

The oxidation of metals that form P-type semiconducting oxide scales, such as NiO on nickel and CoO on cobalt, takes place by outward cation diffusion and inward vacancy diffusion. The large number of cation vacancies precipitate in the scale near the oxide-metal interface and may coalesce to form macroscopic pores, resulting in a transition from a dense, columnar scale to a duplex scale which contains an inner, fine-grained, equiaxed, porous layer. Increasing temperature and/or purity eliminate the transition, which has been found to depend upon oxide plasticity. The mechanical properties of bulk nickel oxides having a range of porosities have been studied in compression. Three regimes were observed: (1) brittle at low temperatures, (2) ductile at elevated temperatures, and (3) a transition region at intermediate temperatures. Fracture strength in the brittle region was strongly dependent on porosity due to the effect of pores on the elastic modulus and the size of fracture-initiating flaws. The plastic flow stress in the ductile region depended primarily on grain size and impurity content except for very porous materials in which porosity substantially reduced the plastic flow stress. The development of the duplex structure in scales during oxidation has been shown to depend upon inhibition of slip on the {110} 110 system in the highly textured grains rather than by diffusion-controlled processes such as creep. The duplex structure forms when the rate of deformation of the scale is less than the rate of void formation. Grain size, porosity, and impurities play an important role; all of these effects are discussed in detail.Research sponsored by the Office of Naval Research, Mathematics and Information Sciences Division, under Contract ONR N00014-69-A-0200-4021, NR-048-239.     

Uptake of blood triglyceride by various tissues

Triglycerides are transported in the blood in chylomicrons and very low density lipoproteins. Electron microscopic studies indicate that these particles, which range in diameter from 0.03–0.6 μ, cannot cross the capillary endothelium in most tissues. There is now considerable evidence that the triglycerides are hydrolyzed to free fatty acids (FFA) during uptake and that this process is catalyzed by lipoprotein lipase. The enzyme is found in nearly all tissues that utilize circulating triglyceride, and the level of activity, in individual tissues, varies with nutritional and physiological states that affect triglyceride uptake, such as fasting, diabetes and pregnancy. Studies in perfused adipose tissue with doubly labeled chylomicrons showed that hydrolysis occurs outside of the blood stream. Two-thirds of the fatty acids are incorporated into tissue triglyceride and the rest are release as FFA, with glycerol, to the blood. Infusion of heparin causes immediate release of lipoprotein lipase activity to the blood and decreases the amount of chylomicron-triglyceride hydrolyzed by the tissue. Electron microscopic cytochemical studies showed that hydrolysis of blood glycerides by lipoprotein lipase in adipose tissue occurs within the capillary endothelial cells and in the subendothelial space near the pericytes, but not in the capillary lumen or near the fat cells. The results indicate that the fatty acids of chylomicrons cross the capillary endothelium as glycerides and FFA, within a membrane-bounded system, and cross the extravascular space to the fat cells as FFA. Presented at the AOCS Meeting, Atlantic City, October 1971.     

Development of color in fats stabilized with amino-hexose-reductones

Summary Amino reductones derived from hexoses were evaluated for color development in heated, oxidizing fat systems. Browning was observed to some extent with all the amino-hexose-reductones. The brown color frequently faded upon long heating of the oils. The density of color increased with reductone concentration and varied markedly among the different amino reductones. Morpholino-hexose-reductone could be used in lard and vegetable oils at concentrations up to 0.01% without introducing visually detectable amounts of color. Heating soybean oil solutions of the amino reductones at 100°C. under vacuum slowly destroyed the reductone but did not cause development of color. Air or oxygen was required for color production. Addition of citric acid along with the reductone reduced the amount of color developed. Reductones in fat systems show similarities in browning to reductones in aqueous systems. New considerations for the mechanism of antioxidation by polyphenols and reductones in oils are presented. Presented at the spring meeting, American Oil Chemists’ Society. New Orleans, La., April 28-May 1, 1957.     

Oxidation and quality of soybean oil: A preliminary study of the anisidine test

The anisidine test, a measure of secondary oxidation products in glyceride oils, was applied to a number of soybean salad oils processed from sound and damaged soybeans. A highly significant correlation (−0.68) was found between the anisidine values of salad oils from sound soybeans and their flavor scores. Multiple correlations between flavor scores, anisidine, and peroxide values yielded a correlation of 0.81 and provided a method for predicting the initial flavor scores of sound soybean salad oils. Similar data for oils from damaged beans gave a highly significant, but lower, correlation (−0.65). Comparative studies indicated that sound crude oils usually contain lower levels of oxidation products than damaged crude. Oxidation in both sound and damaged crudes increased roughly in proportion to iron content. Reproducibility of the test and the effects of hydrogenation, accelerated storage, and fluorescent light on anisidine values were studied. Analysis of damaged oils before and after deodorization showed that little, if any, reduction of anisidine value occurred. Deodorization of sound oils, however, lowered anisidine values. In comparison with damaged oils, the anisidine values of sound oils were lower at comparable stages of processing. The poor quality of damaged soybean oil was substantiated by organoleptic evaluations. Flavor scores of oils given special processing treatments increased as anisidine values decreased.