Antifungal activity of 2 lactic acid bacteria of the Weissella genus isolated from food

Abstract: In the present study, a total of 116 lactic acid bacteria (LAB) strains isolated from Mill flour and fermented cassava were screened for their antifungal activity. Three strains among 116 were selected for their strongest inhibitory activity against food molds. These 3 strains were Lactobacillus plantarum VE56, Weissella cibaria FMF4B16, and W. paramesenteroides LC11. The compounds responsible for the antifungal activity were investigated. The strains displayed an inhibitory activity against targeted molds at acidic pH. However, the influence of organic acids was rejected according to the calculated minimal inhibitory concentration (MIC). Antifungal compounds were investigated in the cell‐free supernatants and phenyllactic acid (PLA) was detected in different amounts with a maximal concentration for Lb. plantarum VE56 (0.56 mM). Hydroxy fatty acid, such as 2‐hydroxy‐4‐methylpentanoic acid, was also produced and involved in the inhibitory activity of Lb. plantarum VE56 and W. paramesenteroides LC11. Antifungal LAB are known to produce PLA and 3‐hydroxy fatty acids and other organic acids with antifungal activity. This short communication focuses on antifungal activity from Weissella genus. The antifungal activity was attributed to antifungal compounds identified such as PLA, 2‐hydroxy‐4‐methylpentanoic acid, and other organic acids. Nevertheless, the concentration produced in the cell‐free supernatant was too low to compare to their MIC, suggesting that the inhibitory activity was caused by a synergy of these different compounds. Practical Application: Antifungal LAB are interesting to prevent food spoilage in fermented food and prolong their shelf life. In this way, chemical preservatives could be avoided and replaced by natural preservatives.     

Simulation and thermoeconomic analysis of different configurations of gas turbine (GT)-based dual-purpose power and desalination plants (DPPDP) and hybrid plants (HP)

This paper contains a simulation and a thermoeconomic analysis of several configurations of gas turbine (GT)-based dual-purpose power and desalination plants (DPPDP): Gas turbine with reverse osmosis (GT+RO), combined cycle with reverse osmosis (CC+RO), combined cycle with multi-effect distillation (CC+MED) and two different hybrid plant (HP) arrangements combining CC, MED and RO (CC+MED+RO, CC+MED+RO_bis). The last two configurations only differ from the feed solution to the MED units (raw seawater or brine coming from the RO discharge). A complete thermodynamic simulation at both design and at part load conditions has been made, as well as an exergy and an exergo-economic (thermoeconomic) analysis of each configuration, in order to compare the evolution of the water and electricity cost for different arrangements. The results show that even for a significantly reduced fuel cost (1.42 $/GJ), the CC is much more profitable than a GT operating in open cycle, with electricity cost values of 1.647 and 2.166 c$/kWh, respectively. As was expected, RO is more efficient and profitable than MED desalination processes, the difference in the obtained desalted water cost being significant. In the hybrid configuration with MED fed by the RO brine discharge, a decrease in the equivalent electrical consumption of nearly 2 kWh/m³ was achieved, but even in this case RO was more efficient (14.15 vs. 4.048 kWh/m³). The evolution of electricity cost in each configuration is more similar at part load operation than at full load, but in the case of water cost, RO is once again more profitable and less sensitive to load variations. Costs given in this paper correspond to investment and fuel costs. Further, profitability and operation strategies of HP, i.e., DPPDP combining distillation and membrane processes, are also analyzed. It is shown that HP can be more profitable than RO plants in the case of increasing the water production capacity of existing DPPDP, because the profit margin of HP remains positive within a substantial range for fuel price and investment costs. The operation strategies of HP were also studied in detail (by means of linear optimization) in order to minimize production costs; and it was concluded that electricity cost minimization gives the same result as the minimization of whole production cost; and water cost minimization could give a lower water cost than in the previous cases, but could lead to prohibitive electricity cost.     

Stability of fluorinated parylenes to oxygen reactive-ion etching under aluminum,aluminum oxide,and tantalum nitride overlayers

The fluorine stability of two parylenes, aliphatic-fluorinated AF-4 (α, α, α′, α′ poly(p-tetrafluoroxylylene) and aromatic-fluorinated VT-4 (2, 3, 5, 6 poly(p-tetrafluoroxylylene), were investigated underneath Al, Al₂O₃, and TaN_X overlayers with and without exposure to oxygen reactive-ion etching (RIE). No fluorine diffusion was observed for Al films deposited onto the as-received parylenes. However, after oxygen RIE, x-ray photoelectron spectroscopy (XPS) depth profiling detected fluorine diffusion throughout Al and to a lesser extent Al₂O₃ but in contrast to Ta_2.67N. Metal-fluoride bonding was evident at the metal/parylene interface for all the overlayers after the parylene was exposed to oxygen RIE and annealed.     

Progress in emitter wrap-through solar cell fabrication on boron doped Czochralski-grown silicon

We report on RISE-EWT (Rear Interdigitated Single Evaporation-Emitter Wrap-Through) solar cells on full area (12.5×12.5 cm²) pseudo square boron doped Czochralski-grown silicon wafers. We investigate the main efficiency optimisation factors of these cells by investigating the dependence of RISE-EWT cell parameters on the base dopant concentration N_A. We furthermore detail the effects of large feature sizes in base and emitter regions at the rear of the solar cell and investigate these effects with particular attention to the edge regions. EWT solar cells typically exhibit rather low fill factors. However, our results show that the improved fill factors can be achieved by increasing N_A, which in return leads to optimised efficiency values. For our RISE-EWT solar cells made from boron doped Cz-Si wafers, this benefit is maintained even after light-induced degradation. Our investigation of edge area related effects shows the importance of proper cell design in these areas, leading to a further 2.8% absolute improvement in the fill factor. Combining increased base dopant concentration with optimised edge design, we achieve 19.0% efficiency on (12.5×12.5 cm²) boron doped Cz silicon wafers before light-induced degradation, resulting in 18.1% efficiency in the light-degraded state.     

Characterization of a polarized porcine uterine epithelial model system

The aim of this study was to elucidate the possible causes of elevated low-density lipoprotein (LDL)-cholesterol levels in transplanted patients treated with the immunosuppressant drug, cyclosporine. HepG2 cells, from a well-differentiated cell-line of hepatoma cells, were cultured and used as a model for in vitro hepatocytic LDL uptake. Different concentrations of cyclosporine, which were within the range of concentrations found in humans treated with cyclosporine, were added to tissue culture medium together with 125I-LDL. The results showed that cyclosporine reduced LDL uptake and degradation in HepG2 cells by about 25%. The cells were also pretreated with cyclosporine for 1 to 24 hours and then incubated with new medium containing labeled LDL for 2 hours at 4 degrees C in an LDL-binding assay. The data showed that cyclosporine reduced the subsequent LDL binding. Cyclosporine has no toxic effects on HepG2 cells, as shown by unchanged growth capacity of the cells. By means of a 50-fold excess of unlabeled LDL, a monoclonal anti-LDL receptor antibody, and dextran sulfate, we also evaluated if this inhibition of LDL binding occurred through the LDL receptor-mediated pathway, through non-LDL receptor-mediated pathways, or through both. The results show that cyclosporine reduces LDL binding and uptake by mainly inhibiting the LDL receptor-mediated pathway. We also studied the effect of the LDL-cyclosporine complex on the binding of labelled LDL. The presence of cyclosporine in the LDL particle does not influence the binding behaviour of LDL to its receptor. We also found that cyclosporine reduces the expression of the LDL receptor messenger RNA (mRNA) by about 40%. Thus, the interpretation of this study is that cyclosporine can cause an increase in LDL-cholesterol in the plasma of transplantation patients by reducing the catabolism of LDL in the liver by inhibiting mainly the LDL receptor-mediated catabolism through an effect on LDL receptor synthesis.     

Fusion peptides and transmembrane domains of fusion proteins are characterized by different but specific structural properties

Membrane fusion is essential for many biological processes. Though there have been many structure and fusion studies of cellular and viral fusion proteins in the last years, their functional mechanism remains elusive. In particular, the structural modes of operation of the transmembrane domains and viral fusion peptides of fusion proteins during membrane fusion have not been elucidated, although work on de novo designed fusogenic peptides suggested that conformational flexibility was necessary. In addition, the use of different and incompatible measurement criteria has made a comparative overview difficult. Here, we report a systematic structural analysis of viral fusion peptides from different fusion protein classes and transmembrane domains of viral and cellular fusion proteins by using circular dichroism spectroscopy. The data that were obtained demonstrate that class I viral fusion peptides show a structural flexibility between helix and irregular secondary structures, whereas fusion peptides of class II viral fusion proteins are characterized by a stable random coil and turn structure. Thus, conformational flexibility does not seem to be a universal criterion for the fusion activity of a fusion peptide. On the contrary, the transmembrane domains of fusion proteins are distinguished by a structural flexibility between helix and sheet structure that is similar to de novo designed unnatural peptides with high fusion activities (M. W. Hofmann et al. PNAS 2004, 101, 14 776-14 781). Thus, the conformational behavior of the fusogenic unnatural peptides most closely resembles that of fusion protein transmembrane domains, and allows them to be used to gain a deeper understanding of the membrane fusion process.     

Dry granulation of organic powders—dependence of pressure 2D-distribution on different process parameters

Nowadays dry granulation of powders has become a very important research topic because it is the most economic way of granulation, making the particle handling easier, and avoiding the loss of material during particle processing, or particle transfers. This kind of process has been deeply studied but a better knowledge appears necessary to control the great number of parameters of the process. This is particularly important in cases where the nature of the powder may lead to very complex phenomena during compaction.In order to try and optimise dry granulation process for organic compounds, a roll press has been designed with a series of instruments enabling to control the compaction process. The apparatus consists of three parts: a vertical container with rotating steel blades avoiding arches into which the powder is poured, a feeder transferring the powder towards the rolls; the feeder is equipped with an horizontal helical screw in a cylindrical draft tube (10 mm in internal diameter, 500 mm long) and in the end of the feeder, a junction allows the change from the cylindrical symmetry of the feeder to the prismatic symmetry existing in the roll gap. The roll press (0-500 kN, load per unit length 0-) has been developed to record different major classical parameters: the roll speed, the roll gap, the press strength, the rotation angle, and the feeding rate (between 0 and ). In comparison with different kinds of roll press described in the literature, in this work an original instrumentation system has been developed to catch specific data. The 3D-pressure distribution profiles at the interface between powder and the roll wall and the drive torque applied to the rolls were measured. A large-sized smooth steel-made roll (240 mm diameter, 50 mm width) has been chosen to compare the results to the industrial scale.The results obtained with an organic compound exhibited the dependence—sometimes unexpected—of the rotation angle, the feeding and the rotation speed on the pressure distribution, the roll width, and the drive torque.