Biomedical subjects

A Orlov

Publications and source records attributed to A Orlov.

8 recordsLinked to original sources

PubMed2007

Organometallics meet colloid chemistry: a case study in three phases based on molecular carbonyl precursors containing zinc and manganese.

Two organometallic compounds containing zinc and manganese in different ratios are used as single-source precursors for the preparation of various new, bimetallic oxide materials with nanoscaled dimensions. It is shown that the materials synthesis can be performed in the solid-state, the liquid-phase, and even in the gas-phase. The molecular composition of the precursors determines the composition of the resulting materials. In addition, two novel methods for the preparation of highly crystalline metal oxide colloids are presented: The coupling between a gas-phase process and a colloidal approach, and the application of ozone as an oxidant for the transformation of metal carbonyls into oxides in the liquid phase.

Carbon Monoxide↗

PubMed2006

Majority logic gate for magnetic quantum-dot cellular automata.

We describe the operation of, and demonstrate logic functionality in, networks of physically coupled, nanometer-scale magnets designed for digital computation in magnetic quantum-dot cellular automata (MQCA) systems. MQCA offer low power dissipation and high integration density of functional elements and operate at room temperature. The basic MQCA logic gate, that is, the three-input majority logic gate, is demonstrated.

Journal Article↗

PubMed2006

Photocatalytic degradation of water-soluble organic pollutants on TiO2 modified with gold nanoparticles.

Well characterised novel catalysts consisting of TiO2 modified with very small amounts of gold nanoparticles have been applied to the photocatalytic degradation of two important pollutants, methyl tert-butyl ether (MTBE) and 4-chlorophenol, in dilute aqueous solution using a fixed bed flow-through photocatalytic reactor. Although the thermal processing that was necessary for coating the reactor walls with the photocatalysts did lead to some loss of performance, the net gains in activity relative to unmodified TiO2 were nevertheless substantial and in excess of anything previously reported. Improvements in reaction rate by 50% and 100% for the removal of 4-chlorophenol and MTBE, respectively, were achieved. It was also found that effective removal of both pollutants could be achieved at water flow rates that are relevant to field applications involving the photocatalytic clean-up of contaminated groundwater. Due to their very small Au content, the cost of these materials is compatible with large scale use.

Catalysis↗

PubMed2006

Energy cost of cows' grazing activity: Use of the heart rate method and the Global Positioning System for direct field estimation.

This study with grazing beef cows on the range was designed to explore the possibility of determining incremental energy expenditure (EE) in standing, traveling, and grazing relative to that in lying down, by means of continuous monitoring of EE, location, and activity by the heart-rate method, with Global Positioning System (GPS) collars, and by motion sensors in the GPS collars, respectively. Cows were observed on Mediterranean foothill rangeland covered with herbaceous vegetation through 4 seasons of the year. There were 2 stocking rate treatments, and 14 statistical models were evaluated, including one that was a stepwise model. Total daily EE (TEE) was affected by many interdependent factors apart from activity, including season, stocking rate, herbage quality, standing biomass, and reproductive state of the cow. Each model included all activity variables, plus some of the other factors. Across seasons and treatments TEE, in kJ/(kg of BW(0.75) . d), ranged from 469 in densely stocked, nonlactating cows in June to 1,092 in sparsely stocked, lactating cows in April. The cows' daily vertical and horizontal movements ranged from 75 to 174 m and from 1.5 to 4.2 km, respectively. Within a day, time spent traveling (without grazing) ranged from 0 to 32 min, and grazing time ranged from 4.4 to 12.1 h. Cows spent less time grazing (P < 0.001) in the summer, when herbage quality was low, than in winter and spring. Relative to the baseline EE while lying down, the daily increment incurred by grazing ranged from 13 to 48 kJ/(kg of BW(0.75) . d), and that incurred by grazing, standing, and traveling combined ranged from 38 to 74 kJ/(kg of BW(0.75) . d) or 5.8 to 11.4% of TEE. In conclusion, the estimates of activity costs yielded by 11 of the models were similar to one another, whereas those yielded by the stepwise model and the remaining 2 models were 20% smaller. The cost of grazing activity was estimated to be 6.14 J/(kg of BW(0.75) . m), and that of locomotion during grazing was 6.07 J/(kg of BW(0.75) . m), which agree with values obtained for animals and humans by means of a treadmill. The experimental and statistical approach tested here yielded fairly reliable estimations of energy costs of activities in grazing cows.

Animals↗

PubMed2005

Radionuclide migration in forest ecosystems--results of a model validation study.

The primary objective of the IAEA's BIOMASS Forest Working Group (FWG) was to bring together experimental radioecologists and modellers to facilitate the exchange of information which could be used to improve our ability to understand and forecast radionuclide transfers within forests. This paper describes a blind model validation exercise which was conducted by the FWG to test nine models which members of the group had developed in response to the need to predict the fate of radiocaesium in forests in Europe after the Chernobyl accident. The outcomes and conclusions of this exercise are summarised. It was concluded that, as a group, the models are capable of providing an envelope of predictions which can be expected to enclose experimental data for radiocaesium contamination in forests over the time scale tested. However, the models are subject to varying degrees of conceptual uncertainty which gives rise to a very high degree of divergence between individual model predictions, particularly when forecasting edible mushroom contamination. Furthermore, the forecasting capability of the models over future decades currently remains untested.

Ecosystem↗

PubMed2001

Effects of vitamin E supplementation on lipid peroxidation and color retention of salted calf muscle from a diet rich in polyunsaturated fatty acids.

The color of fresh meat is one of the most important quality criteria of raw muscle foods. This red color is principally due to the presence of oxymyoglobin. The present study was undertaken to examine the effect of a diet rich in polyunsaturated fatty acids (PUFA), the addition of NaCl, and the influence of dietary supplementation with vitamin E on calf muscle oxymyoglobin oxidation (color) and lipid peroxidation. Vitamin E was added to the feed at a concentration of 4000 mg/day for 90 days before slaughter. This diet increased the alpha-tocopherol concentration in muscle membrane from 2.6-2.8 to 6.5-7.0 microg/g of fresh weight. It was found that the diet rich in PUFA and, especially, the addition of NaCl increased muscle lipid peroxidation and oxymyoglobin oxidation as indicated by the contents of thiobarbituric acid-reactive substances and substances that impaired color value readings during storage at 4 degrees C. Both undesirable reactions during storage were controlled very efficiently by the presence of a critically high concentration of alpha-tocopherol in the muscle tissues. The findings concerning the antioxidant activity of alpha-tocopherol in this study form additional evidence of its efficient protection against oxidative reactions during storage of muscle tissues and its potential to maintain a high nutritional value in them.

Animal Feed↗

PubMed2000

The influence of recombinant bovine somatotropin on dietary energy level-related growth of Holstein-Friesian bull calves.

Our objective for this study was to assess the effect of recombinant bovine somatotropin (rbST) in overcoming the biological effects attributed to live weight increase and age on growth and fat deposition in male cattle. Holstein-Friesian bull calves (n = 56; 182.2 +/- 14.7 d old) were allotted to four subtreatments in a randomized complete block with a factorial arrangement of two levels of rbST: 0 and 500 mg of Posilac, every 2 wk, and two dietary metabolizable energy (ME) concentrations: low metabolizable energy (LME) and high metabolizable energy (HME); 10 vs 11.3 MJ/kg DM, respectively. The effect of rbST treatment on daily gain was expressed mostly on the HME diets. The rbST treatment had no effect on the animals fed the LME diets before the age of 240 d was reached. Dry matter intake and the effect of rbST treatment on DM intake were inversely related to the energy concentration of the diet. The degree of fatness of the animals was significantly reduced by rbST treatment and significantly increased by energy concentration of the diet. The major effect of rbST, under the experimental conditions, in regards to adipose tissue deposition, was on the fat depots and not on the intramuscular fat. The concentration of bST, IGF-I, and insulin in the plasma was increased (P < .001) owing to rbST treatment. Lower metabolizable energy supply led to a higher (P < .001) plasma bST concentration, nonsignificantly lower plasma IGF-I and thyroid hormone concentrations, and lower (P < .001) plasma insulin concentration. A trend (P = .065) toward an increase in PUFA was found in the muscle of the rbST-treated and the HME diet animals. At a young age, when the natural growth potential is high, rbST treatment will be efficient only when a diet allowing a high digestible energy intake is provided.

Animal Feed↗

PubMed1999

The effects of long-term administration of recombinant bovine somatotropin (Posilac) and Synovex on performance, plasma hormone and amino acid concentration, and muscle and subcutaneous fat fatty acid composition in Holstein-Friesian bull calves.

The effect of recombinant somatotropin (rbST), Synovex (Syn), and their combination (rbST+Syn) on intact male calves was examined in an experiment that lasted an average of 238 d. Holstein-Friesian bull calves were allotted to one of four subtreatments (n = 14/treatment) in a factorial arrangement. There were two levels of rbST (0; rbST) and two levels of the estrogenic growth promoter Synovex (0; Syn). The rbST was administered once every 2 wk as injections of 500 mg of Posilac. Synovex (C and S) was implanted at 90-d intervals. The animals were fed for ad libitum consumption a diet with a metabolizable energy concentration of 11.7 MJ/kg DM and 15% crude protein. The hot carcasses were weighed after the removal of kidney, pelvic, and cod fats, which were weighed separately. The 12th rib cut was saved for analysis. Average daily gain and feed conversion efficiency were increased by rbST treatment by 9% (P < .005) and 10% (P < .016), respectively. There was no significant effect of Syn treatment, nor was there a rbST x Syn interaction. The proportion of the fat of the large depots in the carcass was reduced by 34% (P < .0001) and in the longissimus muscle by 32% (P < .16) owing to the rbST treatment. The plasma concentrations of GH, insulin, and thyroxin were increased by rbST treatment (P < .001, P < .01, and P < .03, respectively). The concentration of IGF-I was not affected. Synovex had no effect on plasma hormone concentration. Plasma essential and nonessential amino acid concentrations were reduced by 14 and 9%, respectively, when rbST was injected. Concentrations of cholesterol and fatty acids in muscle and subcutaneous fat were not affected (P > .072) by the rbST treatment. Synovex increased the monounsaturated fatty acids (MUFA), and the combinaton of Syn with rbST reduced polyunsaturated fatty acid (PUFA) concentration in the longissimus muscle (at the 12th rib). The reduced muscle fat content of the rbST-treated animals was associated with a trend toward an increase in polyunsaturated fatty acids.

Adipose Tissue↗