Structure and thermoelectric properties of higher manganese silicides synthesized by pack cementation

Higher manganese silicides (HMS) are promising alternative materials for middle to high temperature thermoelectric applications as a low-cost, non-toxic and highly stable p-type leg. Many of the preparation methods that have been reported previously require long-time and energy consuming processes, as well as expensive equipment, and often do not result in a material of sufficient quality. In this study, the simple, cost-effective and eco-friendly technique of pack cementation is applied. HMS powders synthesized at different experimental conditions are studied and compared considering their structure, composition, short-term thermal stability in air and thermoelectric properties. X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, thermogravimetry and thermoelectric measurements (in terms of Seebeck coefficient, electrical and thermal conductivity) were employed for the characterization of the material and evaluation of its performance. All samples were identified as HMS and only some negligible traces of MnSi were detected. They moderately oxidize when heated non-isothermally under air atmosphere up to 1473 K, while the presence of HMS remains dominant even at such high temperatures. Their thermoelectric properties were remarkable for an undoped material, with a maximum figure of merit (ZT) of 0.47 at 777 K. Pack cementation appeared to have a great potential as the synthesis route of high-efficiency HMS.     

Effects of heat-activated persulfate oxidation on soil microorganisms

The effects of heat-activated persulfate on indigenous microorganisms and microcosms augmented with Pseudomonas putida KT2440 were studied in laboratory batch reactors with aquifer material. Microscopic enumeration was used to measure the changes in cell density, and acetate consumption was used to evaluate metabolic activity after exposure to activated persulfate. The cell enumerations showed that persulfate concentrations up to 10 g/L did not affect the indigenous microorganisms but were detrimental to P. putida survival. Acetate consumption was inhibited at the highest persulfate dose (10 g/L). The results emphasize the necessity of using multiple toxicity assays and indigenous cultures in order to realistically assess the potential effects of in situ chemical oxidation on soil microorganisms. A comparison to other studies suggests that the effects of activated persulfate on soil microorganisms are less damaging than those of Fenton's reagent and hydrogen peroxide.     

Inhibitory effect of organic acid salts on spoilage flora in culture medium and cured cooked meat products under commercial manufacturing conditions

Lactobacillus curvatus, isolated from a spoiled vacuum-packaged 'pariza' type meat product, was used to inoculate modified MRS broth containing sodium lactate, sodium acetate and potassium sorbate in different concentrations, alone or in inter se combinations. Two commercial preparations (MIX 1 and MIX 2) were also used containing combinations of the above antimicrobials. Results from the preservatives addition to the culture medium showed highest antimicrobial activity in the case of the sodium lactate (2%, 3% or 4%), sodium acetate (0.5%) and potassium sorbate (0.15%) combination. Results from the preservatives addition to two types of thermally processed meats showed that sodium lactate and the combination of sodium lactate, sodium acetate and potassium sorbate were the most effective; extending the products shelf life an additional 10 days. Finally, MIX 1 and MIX 2 suppressed the lactic acid bacteria (LAB) growth in the culture medium but not in the final product.     

System memory effects in the sizing of stand‐alone PV systems

Models based on daily energy balance (or long‐term models) have been widely used as a tool in the stand‐alone photovoltaic (PV) system sizing, mainly with the purpose of obtaining analytical expressions of the relation between the generator size and the storage capacity of the battery. The system can then be designed to meet the reliability requirements of the specific case. However, such models represent the complex operation of a stand‐alone system in an oversimplified way. There is little research so far on the reliability and improvement of such models. Validation and possible modification of a long‐term system model requires comparison of the simulated state of charge (SOC) of the battery with that obtained from an experimental system. In this work, experimental data from a 6‐month operation of a basic stand‐alone PV system have been analysed and compared with modelling results. One obvious improvement that could be applied to the long‐term system model is to account for a charging efficiency of the battery, and this possibility is examined in the present work. However, comparison with the modelling results shows that the data cannot be fitted by simply taking into account battery inefficiency. A method to account for system memory effects in the increase of the battery SOC, imposed by the operation of the regulator, is necessary to accurately model the macroscopic diurnal charging/discharging process. Copyright © 2012 John Wiley & Sons, Ltd.     

CD28null and Regulatory T Cells Are Substantially Disrupted in Patients with End-Stage Renal Disease Due to Diabetes Mellitus

Background: End-stage renal disease (ESRD) is associated with alterations in T-cell immunity, including increased CD28null and reduced regulatory T cells (Tregs). However, whether immune disturbances are due to ESRD or primary disease is not yet clear. As diabetes mellitus is the leading cause of ESRD, we evaluated its impact on the immune profile of ESRD patients. Methods: CD28null, Tregs, and natural killer cells were initially analyzed by flow cytometry in 30 predialysis ESRD patients due to diabetes (DM), 30 non-DM (NDM), and 25 healthy controls. Measurements were repeated after 6 months on hemodialysis (HD) or peritoneal dialysis (CAPD). Results: The percentage of CD4 + CD28null cells, CD8 + CD28null cells, and Tregs showed significant differences in DM, NDM, and controls; mean rank 33.71 vs. 25.68 vs. 18.88, p = 0.006, 37.79 vs. 28.82 vs. 17.08, p = 0.008, and 20.79 vs. 26.12 vs. 41.33, p = 0.001, respectively. DM vs. NDM had increased CD4 + CD28null and CD8 + CD28null cells, 11.5% (1.5%–24%) vs. 4.1% (0–42.3%), p = 0.02 and 61.3% (24%–76%) vs. 43% (5.7%–85%), p = 0.04, respectively. After 6 months on HD but not CAPD, DM showed a significant further increase in CD4 + CD28null cells, from 30 (14–100) to 52.7 (15–203), p = 0.02; and CD8 + CD28null cells, from 137 (56–275) to 266 (103–456), p = 0.01. Conclusions: Diabetes mellitus affects T-cell subtypes even at predialysis stage, though changes become more prominent after commencement on HD.     

Hydrological balance and application of the MedWater Model on Naxos Island

The MedWater model was used to determine both the present and future water balances of the largest water basin on Naxos Island, Greece, comparing water resource availability with water demand while also testing assumptions related to the regional hydrological context and different future scenarios. The model indicated that: the required quantities of water for both irrigation and drinking needs reach their annual maximum values during the summer season; the annual water balance shows a general surplus, but not on a monthly basis; the available quantities of water are not enough to cover irrigation demands during the annual dry period; available water resources maximize in March and are generally under-exploited; and the required volumes of water for both irrigation and direct human consumption will increase in the future.     

Evidence for Novel Action at the Cell‐Binding Site of Human Angiogenin Revealed by Heteronuclear NMR Spectroscopy,in silico and in vivo Studies

A member of the ribonuclease A superfamily, human angiogenin (hAng) is a potent angiogenic factor. Heteronuclear NMR spectroscopy combined with induced‐fit docking revealed a dual binding mode for the most antiangiogenic compound of a series of ribofuranosyl pyrimidine nucleosides that strongly inhibit hAng's angiogenic activity in vivo. While modeling suggests the potential for simultaneous binding of the inhibitors at the active and cell‐binding sites, NMR studies indicate greater affinity for the cell‐binding site than for the active site. Additionally, molecular dynamics simulations at 100 ns confirmed the stability of binding at the cell‐binding site with the predicted protein–ligand interactions, in excellent agreement with the NMR data. This is the first time that a nucleoside inhibitor is reported to completely inhibit the angiogenic activity of hAng in vivo by exerting dual inhibitory activity on hAng, blocking both the entrance of hAng into the cell and its ribonucleolytic activity.