Growth and structural perfection of epitaxial nickel oxide

Nickel oxide single crystals have been grown epitaxially over a wide range of temperature (270° C) by vapour hydrolysis of nickel bromide on to (001) cleavage faces of magnesium oxide. Results are presented showing the dependence of thickness and surface morphology of the crystal on the reaction temperature and the ratio of water vapour to bromide vapour.The dislocation density and bulk imperfections in these crystals have been examined using etch-pit and X-ray topographic techniques. The dislocation density over practically the whole range of growth is about 5×10⁷/cm² and is two orders of magnitude greater than that in the substrate. Above growth temperatures of 640° C, plastic deformation and cleavage of both overgrowth and substrate occurs, and it is shown that thermal stresses induced at the interface on cooling are sufficient for initiation.Annealing of the crystals on the substrate produces a regular network of slip lines, which influences the antiferromagnetic twin domain structure.     

The renal medulla and mechanisms of hypertension in the spontaneously hypertensive rat

A significant number of offspring from brother-sister matings of NIH-Okamoto-Aoki spontaneously hypertensive rats (SHRs) were found to be normotensive at 20 weeks of age. Over 20% of the animals that were hypertensive at this age had mild-to-moderate unilateral hydronephrosis at the time of sacrifice. In over 90% of the rats that did not develop hypertension spontaneously, ligation of one ureter raised blood pressure above 150 mm Hg within 2 weeks. In those rats made hypertensive by obstructing one ureter and in those that developed hypertension with accompanying naturally occurring hydronephrosis, subcutaneous implants of fragmented renal medulla from unrelated normal rats decreased blood pressure to normotensive levels. In contrast, medullary implants had no significant effect in rats developing hypertension spontaneously without hydronephrosis. Renal inner medullary plasma flow was low in the obstructed kidneys of hydronephrotic hypertensive SHRs but was elevated in the kidneys of nonhydronephrotic hypertensive SHRs. The hypertension in hydronephrotic SHRs appears to be related to an impairment of the antihypertensive function of the renal medulla. Such an impairment of medullary antihypertensive function does not appear to play a significant role in the hypertension in SHRs without hydronephrosis.     

Congruent strategies for carbohydrate sequencing. 3. OSCAR: an algorithm for assigning oligosaccharide topology from MSn data

This is the third in a sequence of reports devoted to the development of congruent strategies for carbohydrate sequencing. Two previous reports outlined the strategies for observing structural detail from MSn data and introduced tools that compile, search, and compare fragment spectra in a bottom-up approach to oligosaccharide sequencing. In this third report, we introduce the operational details of an algorithm that we define as the Oligosaccharide Subtree Constraint Algorithm (OSCAR). This algorithm assimilates analyst-selected MSn ion fragmentation pathways into oligosaccharide topology (branching and linkage) using what may be considered a top-down sequencing strategy. Guided by a series of logical constraints, this de novo algorithm provides molecular topology without presumed biosynthetic constraints or external comparisons. In this introductory study, OSCAR is applied to a series of permethylated oligomers and isomeric glycans, and topologies are assigned in a few hundredths of a second.     

Lipid metabolism during lactation: a review of adipose tissue-liver interactions and the development of fatty liver

Fatty acids are the major source of energy for most tissues during periods of negative energy balance; however, fatty acids can, in some circumstances, have pathological effects. Fatty acids are stored as triacylglycerols (TAG), mostly in the various adipose tissue depots of the body. However, if blood unesterified fatty acid (NEFA) levels are elevated for prolonged periods, as may occur during lactation or obesity, TAG can accumulate in other tissues including liver and muscle cells (myocytes), and this can have pathological consequences such as the development of ketosis (Grummer, 1993; Drackley et al. 2001) or type 2 diabetes (Boden & Shulman, 2002; McGarry, 2002).     

New developments in cocoa shade studies in Ghana

Attention is drawn to the lack of confirmation for the results of the Amelonado cocoa shade and manurial experiment, Tafo, K1. The shade of this experiment has recently been determined as reducing the illumination of the cocoa to about 30% ambient light intensity. A survey of local farms has shown their shade to be highly variable on average reducing illumination to about 40% ambient light. Results of another experiment, and recent yield trends of various unshaded plots at Tafo, are reported. They are in some disagreement with conclusions previously drawn from the results of Tafo K1 and with previous reports of establishing cocoa on clear-felled land. It appears that the maintenance of a closed canopy is essential to the success of deshaded cocoa. Possible factors are reduction of insect attack, suppression of weed growth, preservation of soil structure, and provision of suitable microclimate. It is suggested that the use of herbicides may be a critical adjunct to the rehabilitation of unshaded cocoa whose canopy has become broken. Breeding programmes should consider variation in capacity to flourish in bright sunlight.     

Influence of lecithin on the chromatography of steroidal glucosiduronates in chloroform/formamide

The interaction between lecithin and steroidal glucosiduronates was investigated by use of partition chromatography in chloroform/formamide and infrared spectroscopy. It was observed that lecithin increases the solubility of both glucosiduronic acids and esters in chloroform and concluded that this phenomenon occurs because of the formation of hydrogen bonds between the phosphodiester group of lecithin and hydroxyl groups of the steroid conjugates.     

Kinetic study of gossypol fixation in cottonseed oil

Summary It was shown in experiments carried out under anaerobic conditions that the fixation of gossypol in cottonseed oil is a reaction of the second order with respect to gossypol. In other words, the rate of fixation is proportional to the square of the gossypol concentration in the oil. The rate of fixation is temperature-dependent and increases 22-fold with an increase in temperature from 40° to 80°C. Presented at the 50th Annual Meeting of the American Oil Chemists' Society, New Orleans, La., April 20–22, 1959. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture.     

Plant-derived polyphenols attenuate lipopolysaccharide-induced nitric oxide and tumour necrosis factor production in murine microglia and macrophages

Lipopolysaccharides released during bacterial infections induce the expression of pro-inflammatory cytokines and lead to complications such as neuronal damage in the CNS and septic shock in the periphery. While the initial infection is treated by antibiotics, anti-inflammatory agents would be advantageous add-on medications. In order to identify such compounds, we have compared 29 commercially available polyphenol-containing plant extracts and pure compounds for their ability to prevent LPS-induced up-regulation of NO production. Among the botanical extracts, bearberry and grape seed were the most active preparations, exhibiting IC(50) values of around 20 mug/mL. Among the pure compounds, IC(50) values for apigenin, diosmetin and silybin were 15, 19 and 12 muM, in N-11 murine microglia, and 7, 16 and 25 muM, in RAW 264.7 murine macrophages, respectively. In addition, these flavonoids were also able to down-regulate LPS-induced tumour necrosis factor production. Structure-activity relationships of the flavonoids demonstrated three distinct principles: (i) flavonoid-aglycons are more potent than the corresponding glycosides, (ii) flavonoids with a 4'-OH substitution in the B-ring are more potent than those with a 3'-OH-4'-methoxy substitution, (iii) flavonoids of the flavone type (with a C2=C3 double bond) are more potent than those of the flavanone type (with a at C2-C3 single bond).     

Effect of strongly competing background compounds on the kinetics of trace organic contaminant desorption from activated carbon

Strongly competing (SC) compounds, naturally found in any drinking water source, are known to decrease the adsorption capacity of activated carbon for trace contaminants. While the effect of these substances on the capacity and adsorption kinetics of trace contaminants is fairly well studied, relatively little is known about their impact on desorption kinetics. The purpose of this study was to investigate the relationship between SC matter and trace compound desorption kinetics. A surrogate SC compound, 1,4-dichlorobenzene (p-DCB), was used to displace the preadsorbed target trace contaminant, atrazine, from powdered activated carbon (PAC). The initial concentrations of p-DCB and atrazine were varied to achieve different degrees of competition to atrazine. Atrazine's desorption diffusion coefficient was found to increase with increasing adsorbed concentration of the SC matter, expressed as an equivalent background compound (EBC).The EBC was modeled with atrazine-like adsorption properties, thus representing the portion of p-DCB that competed to occupy atrazine adsorption sites. The increase in atrazine diffusion rate can be explained by a shift from surface diffusion to diffusion through the carbon's pores as the availability of surface sites decreased due to the EBC's competition. The observed desorption kinetic relationship was consistent with the effect of SC competition on adsorption kinetics; further, the effect was consistent for three different types of SC matter. These findings highlight that the impact of SC matter on activated carbon applications could be either detrimental (displacing adsorbed trace contaminants and enhancing their rate of release) or beneficial (offsetting pore constriction effects by enhancing their rate of uptake).