The new method of ZnIn2S4 synthesis on the titania nanotubes substrate with enhanced stability and photoelectrochemical performance.

In this work, ZnIn2S4 layers were obtained on fluorine doped tin oxide (FTO) glass and TiO2 nanotubes (TiO2NT) using a hydrothermal process as photoanodes for photoelectrochemical (PEC) water splitting. Then, samples were annealed and the effect of the annealing temperature was investigated. Optimization of the deposition process and annealing of ZnIn2S4 layers made it possible to obtain an FTO-based material generating a photocurrent of 1.2 mA cm-2 at 1.62 V vs. RHE in a neutral medium. In contrast, the highest photocurrent in the neutral electrolyte obtained for the TiO2NT-based photoanode reached 0.5 mA cm-2 at 1.62 V vs. RHE. In addition, the use of a strongly acidic electrolyte allowed the generated photocurrent by the TiO2NT-based photoanode to increase to 3.02 mA cm-2 at 0.31 V vs. RHE. Despite a weaker photoresponse in neutral electrolyte than the optimized FTO-based photoanode, the use of TiO2NT as a substrate allowed for a significant increase in the photoanode's operating time. After 2 h of illumination, the photocurrent response of the TiO2NT-based photoanode was 0.21 mA cm-2, which was 42% of the initial value. In contrast, the FTO-based photoanode after the same time generated a photocurrent of 0.02 mA cm-2 which was only 1% of the initial value. The results indicated that the use of TiO2 nanotubes as a substrate for ZnIn2S4 deposition increases the photoanode's long-term stability in photoelectrochemical water splitting. The proposed charge transfer mechanism suggested that the heterojunction between ZnIn2S4 and TiO2 played an important role in improving the stability of the material by supporting charge separation.

Structure and transport properties of triple-conducting Ba x Sr1-x Ti1-y Fe y O3-δ oxides.

In this work, Ba x Sr1-x Ti1-y Fe y O3-δ perovskite-based mixed conducting ceramics (for x = 0, 0.2, 0.5 and y = 0.1, 0.8) were synthesized and studied. The structural analysis based on the X-ray diffraction results showed significant changes in the unit cell volume and Fe(Ti)-O distance as a function of Ba content. The morphology of the synthesized samples studied by means of scanning electron microscopy has shown different microstructures for different contents of barium and iron. Electrochemical impedance spectroscopy studies of transport properties in a wide temperature range in the dry- and wet air confirmed the influence of barium cations on charge transport in the studied samples. The total conductivity values were in the range of 10-3 to 100 S cm-1 at 600 °C. Depending on the barium and iron content, the observed change of conductivity either increases or decreases in humidified air. Thermogravimetric measurements have shown the existence of proton defects in some of the analysed materials. The highest observed molar proton concentration, equal to 5.0 × 10-2 mol mol-1 at 300 °C, was obtained for Ba0.2Sr0.8Ti0.9Fe0.1O2.95. The relations between the structure, morphology and electrical conductivity were discussed.

Nano Tin/Tin Oxide Attached onto Graphene Oxide Skeleton as a Fluorine Free Anode Material for Lithium-Ion Batteries.

Herein, we show a composite formation method of tin/tin oxide nanoparticles with graphene oxide and CMC based on laser ablation technique as an electrode material for energy storage devices. The material exhibited a three-dimensional conducting graphene oxide network decorated with tin or tin oxide nanoparticles. The structure, homogeneous distribution of nanoparticles, and direct contact between inorganic and organic parts were confirmed by scanning electron microscopy and high-resolution transmission electron spectroscopy. Electrochemical performances of composite electrode material showed a reversible capacity of 644 mAh/g at a current density equal to 35 mA/g, and 424 mAh/g at 140 mA/g. The capacity retention of 90% after 250 cycles show that tested electrode material is suitable as a negative electrode for lithium-ion batteries.

High Frequency of Arterial Hypertension in Patients After Liver Transplantation.

BACKGROUND: Cardiovascular diseases are among the most frequent causes of patient death after liver transplantation. The aim of this retrospective clinical study was to estimate the prevalence of arterial hypertension among patients after successful liver transplantation and the role of immunosuppressive drugs in the pathogenesis of hypertension in these patients. PATIENTS AND METHODS: A total of 88 patients (age 47 .5 ±  12.1 years; 33 women and 55 men) who had undergone successful liver transplantation and completed 24 months follow-up were studied. The results are presented as means with standard deviations. RESULTS: At 1, 12, and 24 months after liver transplantation, the prevalences of hypertension were 44.3%, 54.5%, and 62.5%, respectively. Systolic and diastolic blood pressure in these months were 124.1 ± 14.8, 132.8 ± 19.1, and 135.2 ± 17.3 mm Hg and 83.3 ± 12.0, 87.3 ± 11.1, and 87.9 ± 11.1 mm Hg, respectively. The estimated glomerular filtration rates were 77.8 ± 32.3, 80.3 ± 30.8, and 78.8 ± 29.1 mL/min/1.73 m(2), respectively. Arterial hypertension was significantly more frequent in patients treated with cyclosporine A than in those treated with tacrolimus (P = .004) or everolimus (P = .005). In patients treated with tacrolimus, a positive correlation was found between tacrolimus blood concentration and systolic blood pressure (R = 0.34; P = .01) and a negative correlation was found between estimated glomerular filtration rate and systolic blood pressure (R = -0.28; P = .02). CONCLUSIONS: Based on study findings, the following conclusions were drawn: arterial hypertension occurs in more than 50% of patients after liver transplantation (significantly higher frequency than in the general population); calcineurin inhibitors may participate in the pathogenesis of arterial hypertension in patients after successful liver transplantation; and the clinical importance of these findings and the influence on cardiovascular outcome of the liver transplant recipients need further investigation.

Proton Conducting Ceramic Powder Synthesis by a Low Temperature Method.

Molten salt synthesis (MSS) is a simple method for the preparation of ceramic powders with specific morphology. The main role of the molten salts is to increase the reaction rate and lower the reaction temperature. It occurs because of much higher mobility of reactants in the liquid medium than in the solid state. In this work the molten salt synthesis was applied to produce ceramic powders of La0.995Ca0.005NbO4 and BaCe(0.9-x)Zr(x)Y0.1O3. Single-phase lanthanum niobate formed in all studied conditions of the synthesis, whereas in the case of barium cerate-zirconate MSS led to forming two crystalline phases: barium cerate and barium zirconate. The heating temperature and time as well as the salt content most strongly influenced the shape and size of particles. The influence of other parameters on the powder morphology was weaker. Despite differences in size and morphology, all groups of the La0.995Ca0.005NbO4 powder obtained with the MSS method pressed into pellets and sintered gave a dense ceramic material. On the other hand in the case of barium cerate-zirconate regardless of synthesis and sintering conditions the ceramics were porous.

Age-related increase of frequency of a new, phenotypically distinct subpopulation of human peripheral blood T cells expressing lowered levels of CD4.

Aging is associated with modifications of T-cell phenotype and function, leading to impaired activation in response to both new and recall antigens. It is not known if T-cell activation results in elimination of a number of the CD4 molecules from the cell surface, as is the case with CD3/T-cell receptor complexes, or how aging influences the process. The T cells of young and elderly donors with reduced expression of CD4 were examined to see whether these cells exhibit other phenotypic features suggesting their active state. It was found that T lymphocytes expressing CD4 can be divided into 2 semidiscrete subpopulations: the major (CD4(+)) population, in which the level of expression of CD4 is constant and high, and a minor population (CD4(lo)), in which the expression of CD4 can be up to an order of magnitude lower than on the CD4(+) cells. The proportion of CD4(lo) cells is age dependent and highly variable in the apparently healthy human population, with the expression of CD4 ranging from around 10% of all peripheral blood lymphocytes in the young to more than 30% in the elderly. Lowered expression of CD4 is correlated with a reduced expression of CD3, as well as with a decreased amount of CD28 and CD95Fas. Activation of CD4(lo) cells is suggested by their expression of CD25 and increased amounts of HLA-DR. Phenotypic characteristics of the CD4(lo) T-cell subpopulation suggest that it might be formed by (perhaps chronically) activated, temporarily apoptosis-resistant cells, possibly accumulating in the elderly. (Blood. 2001;98:1100-1107)

[Homocysteine as a risk factor for atherosclerosis]. / Homocysteina jako czynnik ryzyka rozwoju miazdzycy.

This article presents current views on the significance of homocysteine as a potential risk factor for atherosclerosis. The majority of numerous and extensive comparative examinations indicate that considerable hyperhomocysteinemia is an independent risk factor for the development of the premature atherosclerotic lesions. Because of that experts of the Nutrition Committee of American Heart Association published in 1999 the recommendations for the application of the preventive diet rich in vitamins B6, B12 and folic acid.

Pulsed-accelerated-flow spectrometer with position-resolved observation.

The title instrument (PAF-PRO) permits the progress of rapid reactions to be monitored at 128 positions along a 2 cm observation cell as reactants flow down the cell. A decelerated push is used to give velocity changes from 21 to 2 m s(-1) during a time interval of 384 ms. Variation of flow velocity allows reaction rate constants to be resolved from the physical mixing process. The flow system brings the reacting solutions together in a 10-jet radial mixer 0.32 cm before the mixture enters the observation tube (0.203 cm width, 1.945 cm length). A masked charge-coupled device (CCD) is the array detector used to obtain transmittance data as a function of position and velocity. The masked portion of the CCD serves as a dynamic memory buffer for fast data acquisition. Pseudo-first-order rate constants are measured from 200 to 12 000 s(-1). The instrument also is calibrated for second-order reactions (equal concentrations) with initial half-lives of 0.3-1.5 ms. Applications of the PAF-PRO system for the study of fast multistep reactions are presented.

Characteristics of a scintillator-based daily quality assurance device for radiation oncology beams.

A plastic scintillator based device marketed as a "DCT 444" is investigated for daily quality assurance (QA) of radiation beams. Variations in DCT responses were studied for three identical devices with beam, energy, distance, dose, dose rate, and orientations. The effects of gantry, collimator, and patient support assembly (PSA) rotations were investigated at photon energies of 6, 10, and 18 MV and electron energies in the range of 5-20 MeV from three different linear accelerators. The short and long term linearity, reproducibility, and radiation damage were also investigated in kilovoltage and megavoltage beams. Results indicate that the DCT response is linear with dose and dose rate, but shows directional dependence for all beams. The response is dependent on its orientation and the angle of rotations of collimator, gantry, and PSA of the linear accelerator. When the collimator is rotated through 0-36 degrees, the DCT response varied within +/- 4.5% and +/- 7.2% for the 6 MV and 18 MV beams, respectively. With PSA rotation, deviations up to +/- 11% were noted. The DCT response is symmetric across 0 degrees and peaks at +/- 60% PSA angle for all accelerators and beam energies. The effect of backscattering medium on DCT response is noted for all beams but significant for kilovoltage beams. A deviation as high as 30% was observed when DCT was placed on a thick polystyrene phantom. The long term stability studied over 25 months showed varied signal losses possibly due to radiation damage. However, there is no noticeable signal loss over a short period of time (2-4 weeks). The lightweight DCT device is linear with dose and dose rate, stable, and easy to operate. It stores ten readings that can be downloaded to a personal computer. This study indicates that DCT-444 is a suitable QA tool for central axis dose measurement. However, proper precaution is needed as this device exhibits directional and positional dependence. For a meaningful QA result of a radiation unit, the daily QA setup geometry should be identical to that used for calibration of the DCT device.

The relationship between apoptosis and atrophy in the irradiated lacrimal gland.

Atrophy is generally considered to be a true late effect of radiation. However, in serous glands, atrophy was thought to be a consequential late effect because serous cells die within hours of irradiation and the apparent effects of atrophy are observed contemporaneously with radiation treatment. Therefore, to determine the pathogenesis of atrophy in serous glands, it is necessary to differentiate between parenchymal loss as a result of direct radiation death of serous cells and parenchymal loss as a result of serous cell death that is secondary to fibrosis, vascular damage, or precursor cell death. The lacrimal glands of 62 rhesus monkeys have been irradiated to single doses of 2.5 to 20 Gy and examined at intervals of 4 hr to 112 days postirradiation. Serous cells (nuclei) and acini were counted in at least 30 high power fields per (dose, time) point. At each dose and time of sacrifice, the average number of nuclei per acinus and the average number of acini per high power field were calculated. Also at each dose and time, the distribution of the number of nuclei per acinus was examined to determine how the frequency of acinar sizes changed as a function of irradiation. The number of cells per acinus appears to rise initially, but this is likely a result of the degranulated cells being physically smaller, yielding an artificially higher count. Within 4 days after 12.5 Gy, the average number of nuclei per acinus approaches control values and remains within the range of controls for at least 112 days. The number of acini per high power field decreases steadily for 30 days after 12.5 Gy. From 30 to 112 days, there is some recovery of this number, but it remains well below control values. At 24 hr, the number of nuclei per acinus shows a distinct dose response up to 20 Gy. However, at 30 days there is no evidence of a dose response for this parameter. These results indicate that even though serous cells die in significant numbers within hours of irradiation, the atrophy of the lacrimal gland (and by extension, the parotid gland) is a result of the death of the serous stem cell or precursor. Consequently, protection of serous cells from radiation apoptosis will not diminish serous gland atrophy.