Optical properties of oxygen vacancies in HfO2 thin films studied by absorption and luminescence spectroscopy.

Hafnium oxide thin films with varying oxygen content were investigated with the goal of finding the optical signature of oxygen vacancies in the film structure. It was found that a reduction of oxygen content in the film leads to changes in both, structural and optical characteristics. Optical absorption spectroscopy, using nanoKelvin calorimetry, revealed an enhanced absorption in the near-ultraviolet (near-UV) and visible wavelength ranges for films with reduced oxygen content, which was attributed to mid-gap electronic states of oxygen vacancies. Absorption in the near-infrared was found to originate from structural defects other than oxygen vacancy. Luminescence generated by continuous-wave 355-nm laser excitation in e-beam films showed significant changes in the spectral profile with oxygen reduction and new band formation linked to oxygen vacancies. The luminescence from oxygen-vacancy states was found to have microsecond-scale lifetimes when compared with nanosecond-scale lifetimes of luminescence attributed to other structural film defects. Laser-damage testing using ultraviolet nanosecond and infrared femtosecond pulses showed a reduction of the damage threshold with increasing number of oxygen vacancies in hafnium oxide films.

Point defects in Sc2O3 thin films by ion beam sputtering.

We show that the concentration of oxygen interstitials trapped in Sc2O3 films by ion beam sputtering from metal targets can be controlled by modifying deposition conditions. We have identified point defects in the form of oxygen interstitials that are present in Sc2O3 films, in significantly high concentrations, i.e., ∼10(18) cm(-3). These results show a correlation between the increase of oxygen interstitials and the increase in stress and optical absorption in the films. Sc2O3 films with the lowest stress and optical absorption loss at 1 µm wavelength were obtained when using a low oxygen partial pressure and low beam voltage.

Isolated canine and murine intestinal cells exhibit a different pattern of fuel utilization for oxidative metabolism.

The amount and type of dietary fiber influences the end-products of fermentation and thus fuel availability to intestinal tissue. Metabolic fuel usage was studied in intestinal cells isolated from dogs consuming a commercial diet or from rats consuming either a commercial rat diet or dog diet to examine preferential fuel usage, the effect of diet, and species differences. Production of 14CO2 was measured by incubating cells in media containing either D-[U-14C]glucose, [1-14C]n-butyrate, L-[U-14C]glutamine, or [1-14C]propionate with or without competing substrates. The presence of a mixture of 5 mM each of glucose, butyrate, propionate, and acetate and 1 mM glutamine in the media decreased CO2 production from glucose, glutamine, and propionate by canine enterocytes (P < 0.05) and from glutamine and propionate by canine colonocytes (P < 0.05). The presence of glutamine in the media decreased glucose oxidation by murine enterocytes, regardless of the diet. Similarly, glutamine decreased glucose oxidation by murine colonocytes (P < 0.05), but only when the rats had consumed the rat diet. Regardless of diet, murine colonocytes oxidized more butyrate (P < 0.01) than did enterocytes, and murine enterocytes tended (P < 0.07) to oxidize more glucose than did colonocytes. The proportion of propionate in colonic contents was higher in dogs than in rats (P < 0.02), and the proportion of butyrate tended to be higher in contents from rats than in those from dogs (P < 0.08). Colonic and cecal wet weights were decreased (P < 0.05) when rats were fed the commercial dog diet. Preferred utilization of substrates by isolated canine enterocytes and colonocytes differed from that of murine intestinal cells. These differences were only partially overcome by feeding the same diet to each species.

Substrate utilization for hepatic gluconeogenesis is altered by increased glucose demand in ruminants.

Hepatocytes isolated from 10 Dorset wethers that were treated with excipient or 1.0 g/d of phlorizin for 72 h were used to determine the effects of increased glucose demand on utilization of [1-(14)C]propionate and [1-(14)C] alanine for oxidative metabolism and gluconeogenesis. Control and phlorizin-treated wethers excreted 0 and 62.8 g/d of glucose into the urine, respectively. Phlorizin treatment tended to increase conversion of propionate and alanine to CO2. A phlorizin x substrate interaction for conversion to glucose indicated that conversion of alanine to glucose was increased more by phlorizin treatment than was conversion of propionate (285 vs 166% of controls). Phlorizin treatment did not affect estimated Ks for conversion of substrates to either CO2 or glucose; however, phlorizin increased estimated Vmax for conversion of substrates to CO2 and tended to increase estimated Vmax for conversion of substrates to glucose. Phlorizin treatment slightly increased the ratio of conversion of propionate to glucose compared with CO2 and slightly decreased the ratio of conversion of alanine to glucose compared with CO2. In vitro addition of 2.5 mM NH4Cl decreased conversion of propionate to CO2 and glucose but had little effect on conversion of alanine to CO2 and glucose. Estimated Ks and Vmax for conversion of substrates to CO2, Ks for conversion of substrates to glucose, and Vmax for conversion of alanine to glucose were not affected by NH4Cl; however, Vmax for conversion of propionate to glucose was decreased by NH4Cl. These data indicate that although utilization of propionate for gluconeogenesis is extensive, amino acids have the potential to increase in importance as gluconeogenic substrates when glucose demand is increased substantially. Furthermore, excess ammonia decreases the capacity of hepatocytes to utilize propionate for oxidation and gluconeogenesis.

Effects of source of carbohydrate and protein and rumen-protected methionine on performance of cows.

Multiparous Holstein cows were fed diets consisting of alfalfa silage, corn silage, and a concentrate mixture containing primarily ground shelled corn or corn gluten feed; the diets were supplemented with 0 or 20 g/d of rumen-protected Met. The 183-d experimental period followed a 21-d covariate period beginning at calving. Data from early lactation (d 22 to 105) and the entire experiment were analyzed. Yields of milk and milk crude protein were not affected by treatment. Corn gluten feed increased the percentages of milk fat and total solids. The rumen-protected Met tended to increase both the crude protein and casein N content of milk. Body weight, milk fat percentage, and yields of milk fat, 3.5% fat-corrected milk, and total solids were greater when ground shelled corn and 20 g/d of rumen-protected Met or corn gluten feed and 0 g/d of rumen-protected Met were fed than when ground shelled corn and 0 g/d of rumen-protected Met or corn gluten feed and 20 g/d of rumen-protected Met were fed. A similar interaction for dry matter intake was significant only during d 22 to 204. Corn gluten feed increased plasma concentrations of His, Ile, Leu, and Val. Rumen-protected Met increased plasma concentrations of Met, decreased His, and tended to decrease Arg, Lys, and Orn. These data suggest that the dietary source of carbohydrate and protein can modulate the response of cows to rumen-protected Met.

Dose response of dairy cows to abomasal administration of four amounts of L-carnitine.

Four Holstein cows were used in a 4 x 4 Latin square design with 21-d periods to determine the response to increasing amounts of L-carnitine infused into the abomasum. During d 1 to 7 of each period, cows were abomasally infused with 4 L/d of water; during the remainder of each period, 0, 3, 6, or 12 g/d of carnitine dissolved in 4 L of water were infused continuously into the abomasum. The DMI, milk yield, and milk composition were not affected by carnitine infusion. Apparent digestibilities of DM, OM, CP, ADF, NDF, and energy decreased linearly, and fatty acid digestibility tended to decrease linearly, when up to 12 g/d of carnitine were infused. Balances of energy and N generally were unaffected by carnitine infusion. The concentrations of carnitine in plasma and urine increased linearly, and that in milk increased quadratically, as the amount of infused carnitine increased; the concentrations of carnitine in plasma and milk appeared to be maximized when 6 g/d of carnitine were infused. Total carnitine excreted and carnitine excretion above basal excretion increased linearly as amounts of infused carnitine increased; however, < or = 23% of the daily carnitine dosage was excreted above basal carnitine excretion. Infusion of up to 12 g/d of carnitine into the abomasum did not improve milk yield or nutrient digestibilities.

A membrane-associated cysteine protease inhibitor from murine hepatoma.

A cysteine protease inhibitor was purified from total membrane fractions of an invasive murine hepatoma, Hepa cl 9. On gel filtration under non-reducing conditions the purified inhibitor was eluted in a single peak of M(r) 10-15 kDa, but resolved as two bands at 14 and 70 kDa on SDS-PAGE under reducing conditions. By isoelectric focusing, the inhibitor ran at an isoelectric point of 4.75. Immunoblotting studies using the enhanced chemiluminescence technique indicated no crossreactivity with monoclonal antibodies to stefin B and cystatin C or with a polyclonal antibody to low M(r) kininogen. In contrast, the 14 kDa and 70 kDa bands both crossreacted with a polyclonal antibody to stefin A, suggesting that the cysteine protease inhibitor associated with Hepa cl 9 membranes may be a modified form of stefin A.

Synthesis and renal vasodilator activity of 2-chlorodopamine and N-substituted derivatives.

A four-step synthesis of 2-chlorodopamine (2b) is presented as well as methods for the syntheses of the N-methyl, ethyl, and n-propyl analogues (2c-e). Compounds 2b and 2c were essentially equipotent to dopamine for increasing renal blood flow in anesthetized dogs that had been treated with the alpha-adrenergic antagonist phenoxybenzamine. The increases in renal blood flow were blocked by the DA1 antagonist (R)-(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine. Compounds 2d and 2e were significantly less potent than dopamine in the same model; the increases in renal blood flow were attenuated by propranolol and blocked by a combination of propranolol and (R)-(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine. The significance of an o-chloro substituent on dopamine analogues for the activation of the DA1 receptor is briefly discussed.

Smoking and allergic history as correlative risk factors in pulmonary function performance.

Pulmonary function data were compared with smoking history and past personal and family history of asthma, hay fever and eczema in apparently healthy males age 30 to 39. Mean values for FEV1 and MMEF were significantly lower in smokers with a positive allergic history compared to non-allergic smokers.