The Influence of Fuel and Steam Consumption on Characteristics of Fixed Bed Process of Woody Biomass Steam Gasification with Intensive Heat Supply

Plant biomass is one of the most widespread renewable energy sources. Energy utilization of biomass allows solving some problems associated with the development of off-grid energy systems and the processing of combustible waste (primarily agricultural and forestry waste). This paper is devoted to the study of an allothermal gasification process of plant biomass materials using a kinetic-thermodynamic model developed by the author. The gasification process is considered stationary, and steam is used as a gasification agent. The power of the supplied heat is considered constant (10 kW). One of the significant tasks related to allothermal gasification is to choose flowrate parameters so that the heat supplied is efficiently used in chemical reactions without the threat of reactor overheating. The determination of the boundaries of the safe gasifier operation involved variant calculations with a view to optimizing the gasification conditions. The calculation results show that the allothermal gasification process can proceed with a thermochemical efficiency of about 70%. For each fixed fuel consumption level, there is an optimal fuel-steam ratio. The complete conversion of biomass requires sufficiently high temperatures. The produced gas contains a significant steam fraction (>50 vol%) even under optimal conditions. The calculated fraction of hydrogen in dry gas is up to 60vol%. The data obtained can be used to assess the efficiency of energy units with biomass gasification using high-temperature sources, for example, in systems that use and store solar thermal energy.

Effect of La Addition on Solidification Behavior and Phase Composition of Cast Al-Mg-Si Alloy

The current study focusses on the phase composition, solidification path, and microstructure evaluation of gravity cast Al-4Mg-0.5Si-xLa aluminum alloy, where x = 0, 0.1, 0.25, 0.5, 0.75, and 1 wt.% La. A computational CalPhaD approach implemented in Thermo-Calc software and scanning electron microscopy technique equipped with electron microprobe analysis (EMPA) was employed to assess its above-mentioned characteristics. The thermodynamic analysis showed that the equilibrium solidification path of La-containing Al-Mg-Si alloys consists of only binary phases LaSi2 and Mg2Si precipitation along with α-Al from the liquid and further solid-state transformation of this mixture into α-Al + Al11La3 + Mg2Si + Al3Mg2 composition. Scheil–Gulliver simulation showed a similar solidification pathway but was accompanied by an increase in the solidification range (from ~55 °C to 210 °C). Furthermore, microstructural observations were congruent with the calculated fraction of phases at 560 °C and related to α-Al + LaSi2 + Mg2Si three-phase region in terms of formation of La-rich phase having both eliminating effect on the eutectic Mg2Si phase. Quantitative EMPA analysis and elemental mapping revealed that the La-rich phase included Al, La, and Si and may be described as Al2LaSi2 phase. This phase shows a visible modifying effect on the eutectic Mg2Si phase, likely due to absorbing on the liquid/solid interface.

DYSLIPIDAEMIA IN CHILDREN ON DIALYSIS AND AFTER KIDNEY TRANSPLANTATION

Cardiovascular complications are the main problems associated with end stage renal disease (ESRD) in adult, which began renal replacement therapy (RRT) in childhood. One of the factors contributing to this can be an imbalance of blood lipids. Aim of the study was to evaluate changes in the lipid profile in children with ESRD, depending on the RRT method and age, and also after kidney transplantation depending on the glomerular filtration rate. Materials and methods. In 91 children with ESRD at the age of 2–17 years who received peritoneal dialysis (PD) or hemodialysis (HD), or after kidney transplantation (Tx), total cholesterol (CH), triglycerides (TG), lipoproteins high density (HDL) ) were measured in 663 samples of blood and calculated fraction of non–HDL (CH – HDL). Dyslipidemia was defined as TG>1,13 mmol/1 (0–9years) and >1,47mmol/l (10–17years), CH> 5,18mmol/l, non–HDL >3,7mmol/l, HDL <1.0 mmol/l. Results. The prevalence of dyslipidemia in children was 90,4% on PD, 65,2% on HD and 32,6% after Tx, mainly due to hypertriglyceridemia in 80,8% on PD, 65,2% on HD and 20,8% after Tx. The levels ofTG and non–HDL were also significantly higher in PD and HD patients than after Tx. Children of the younger age group (2–5 years) on PD had the worst lipid profile. After kidney transplantation a significant reduction of TG and cholesterol was detected in PD patients and only TG in HD patients. Reduction of the glomerular filtration rate in children after kidney transplantation is accompanied by an increase in TG levels. Conclusion. Dyslipidemia is widespread in children on RRT. Preemptive kidney transplantation can prevent the development of severe lipid imbalance which persists of dialysis treatment.

IN VITRO SCREENING OF ACTINIOPTERIS DICHOTOMA FOR ENZYME INHIBITORY ACTIVITY RELATED TO TYPE 2 DIABETES

Actiniopteris dichotoma Mett. (Pteridaceae) is documented in Ayurveda for treatment of Prameha (Diabetes), Atisara and skin diseases. However, the antidiabetic properties of this plant have not been fully validated using scientific tools. The present study screens the A. dichotoma extract and fractions for enzyme inhibitory (α–amylase and α–glucosidase) activity related to type 2 diabetes. The extract was prepared using cold maceration followed by Soxhlation and finally fractionated the combined extracts. Different concentrations (0.1–0.5 mg/mL) of extract and four fractions were subjected to enzyme inhibitory assays. The absorbance was measured at 540 and 405 nm and IC50 values were calculated. Fraction 2 has shown highest α–amylase and α–glucosidase inhibitory activity, (IC50 values are 0.131 and 0.114 mg/mL) which was comparable with acarbose (0.125 and 0.093 mg/mL). Hence, further studies may throw light on the antidiabetic potential of A. dichotoma especially in the management of T2D.

Alloying with Silicon and Copper in Aluminum Alloys

The main aim of the metallurgical investigation was to enhance our understanding of the role Cu and Si have on the development of shrinkage porosity in the as-cast structure, which in turn can affect high cycle fatigue (HCF) properties of Al-9Si-1Cu (W328) and Al- 7Si-4Cu (W319) alloys. In order to achieve this objective a novel approach using thermal analysis and calculated fraction solid techniques was developed to assess mushy zone kinetics, the state between the liquidus and solidus where a solid skeletal α-Al phase and the Al-Si eutectic phase grow at the expense of an inter-dendritic liquid. Specifically, the cooling curve and calculated fraction solid curve were partitioned into segments, which reflect different stages of feeding through the entire solidification event of the alloy. Each partitioned segment corresponds to a stage of feeding, which in turn signifies a relative degree of pore growth susceptibility. Two thermal analysis techniques, both using calibrated thermocouples, were used to precisely understand the solidification path for both the W319 alloy and the W328 alloy.

Mitochondrial function and mitochondria-induced apoptosis in an overstimulated rat ovarian cycle

Female rats were treated with FSH (40 IU/kg) on the first and second diestrus days (D1 and D2) and with LH (40 IU/kg) on the proestrus (P) day to synchronize and maximize ovarian changes. Follicle area increased by 50% from D1 to P, and the estrus (E) phase showed multiple corpora lutea and massive apoptosis. Increased oxygen uptakes (42–102%) were determined in ovary slices and in isolated mitochondria in active state 3 along the proliferation phase (D1-D2-P) that returned to initial values in the E phase. Mitochondrial content and the electron transfer activities of complexes I and IV were also maximal in the P phase (20–79% higher than in D1). Production of NO by mitochondrial nitric oxide synthase (mtNOS), biochemically determined, and the mtNOS functional activity in regulating state 3 oxygen uptake were also maximal at P and 79–88% higher than at D1. The moderately increased rate of NO in the proliferative phase is associated with mitochondrial biogenesis, whereas the high rate of NO generation by mtNOS at phase P appears to trigger mitochondria-dependent apoptosis. The calculated fraction of ovary mitochondria in state 3 was at a minimal value at the P phase. Mitochondrial oxidative damage, with increased thiobarbituric acid-reactive substances and protein carbonyls, indicates progressive mitochondrial dysfunction between phases P and E. The roles of mitochondria as ATP provider, as a source of NO to signal for mitochondrial proliferation and mitochondria-dependent apoptosis, and as a source of O2− and H2O2 appear well adapted to serve the proliferation-apoptosis sequence of the ovarian cycle.

Aerobic Denitrification of Pseudomonas aeruginosa Monitored by Online NAD(P)H Fluorescence

ABSTRACT Continuous cultures of Pseudomonas aeruginosa (ATCC 9027) maintained at different dissolved oxygen concentrations (DO) were studied for the effects of DO on various culture properties, especially aerobic respiration and denitrification. The DO was varied from 0 mg/liter (completely anoxic conditions) to 1.3 mg/liter and measured with optical sensors that could accurately determine very low DO based on oxygen-quenched luminescence. The strain was found to perform aerobic denitrification; while the specific rate decreased with increasing DO, denitrification persisted at approximately 1/8 of the maximum rate (1.7 mmol/g of cells/h) even at relatively high DO (1 to 1.3 mg/liter). In the presence of nitrate, the culture's Monod half-rate saturation constant for O2 was very small, <0.1 mg/liter. Aerobic denitrification appeared to function as an electron-accepting mechanism supplementary to or competitive with aerobic respiration. The shift of the culture's respiratory mechanism was also clearly detected with a fluorometer targeting intracellular NAD(P)H, i.e., the reduced forms of the NAD(P) coenzymes. Comparatively, the NAD(P)H fluorescence under the anoxic, denitrifying conditions (NFUDN) was highest, that under fully aerobic conditions (NFUOX) was lowest, and that under conditions in which both denitrification and aerobic respiration occurred (NFU) was intermediate. Representing a quantitative measure of the culture's “fractional approach” to the fully denitrifying state, the normalized fraction (NFU − NFUOX)/(NFUDN − NFUOX) was correlated with DO and the calculated fraction of electrons accepted by denitrification. The NFU fraction decreased with increasing DO, following an empirical exponential relationship. The fraction of denitrification-accepted electrons increased with the NFU fraction: the increase was gradual and approximately linear at DO of ≥0.1 mg/liter but much sharper at lower DO. Online NAD(P)H fluorescence was demonstrated as a feasible technique for effective monitoring and quantitative description of the microaerobic state of microorganisms.

Comparison of Amplification and Imaging Behaviours of Several Gases In The Environmental Sem

We have investigated the amplification properties of several imaging gases in the Environmental SEM (ESEM) with the intent of forming a set of general guidelines for the selection of gases. In the ElectroScan ESEM, a gas ionisation cascade is used to amplify the secondary electron signals emanating from the specimen surface. The presence of gas in the chamber also gives rise to a pressure dependent background signal derived from ionisation events between gas molecules and high energy primary beam and backscattered electrons. The fraction of secondary electron signal decreases as the pressure is raised. This point is illustrated in figures la and lb which show the calculated fraction of signal contributed by secondary, backscattered, and primary electrons as a function of pressure in helium and water vapour. Helium yields a very pure secondary electron signal over the entire range of pressures shown. Unfortunately, helium does not provide a great deal of signal amplification compared to water vapour (figure 2).

Excretion of ciprofloxacin into the large bowel of the rabbit.

The intestinal elimination of ciprofloxacin in the large bowel was studied in a rabbit model. Segments from the cecum, colon, and sigmoid colon along with their intact blood vessels were isolated and perfused, and their contents were collected over a 90-min period following the administration of a single parenteral dose of 27 mg of ciprofloxacin per kg of body weight. The elimination rates of ciprofloxacin were 0.126 +/- 0.084 micrograms.min-1.cm-2 in the cecum and 0.264 +/- 0.126, 0.11 +/- 0.07, and 0.21 +/- 0.141 micrograms.min-1.cm-2 in the proximal colon, distal colon, and sigmoid colon, respectively. The calculated fraction of ciprofloxacin eliminated in the large bowel was 3% of the parenteral dose administered. The elimination pattern of ciprofloxacin in the large bowel may explain the unusual activity of this fluoroquinolone in modifying the colonic flora.