Controlled Production of Amyloid β Peptide from a Photo‐Triggered,Water‐Soluble Precursor “Click Peptide“

In biological experiments, poor solubility and uncontrolled assembly of amyloid β peptide (Aβ) 1–42 pose significant obstacles to establish an experiment system that clarifies the function of Aβ1–42 in Alzheimer's disease (AD). Herein, as an experimental tool to overcome these problems, we developed a water‐soluble photo‐“click peptide” with a coumarin‐derived photocleavable protective group that is based on an O‐acyl isopeptide method. The click peptide had nearly 100‐fold higher water solubility than Aβ1–42 and did not self‐assemble, as the isomerized structure in its peptide backbone drastically changed the conformation that was derived from Aβ1–42. Moreover, the click peptide afforded Aβ1–42 quickly under physiological conditions (pH 7.4, 37 °C) by photoirradiation followed by an O–N intramolecular acyl migration. Because the in situ production of intact Aβ1–42 from the click peptide could improve the difficulties in handling Aβ1–42 caused by its poor solubility and highly aggregative nature, this click peptide strategy would provide a reliable experiment system for investigating the pathological function of Aβ1–42 in AD.     

Microstructure and Phase Constitution Near the Interface of Explosively Welded Aluminum/Copper Plates

The microstructure changes and the phase constitution within the layers close to the bonding interface strongly influence the properties of bimetallic strips. In this work, the layers near the interface of explosively welded aluminum and copper plates were investigated by means of microscopic observations, mostly with the use of transmission electron microscopy (TEM) equipped with energy dispersive spectrometry (EDX). The study was focused on the identification of the intermetallic phases, the possible interdiffusion between the copper and the aluminum, and the changes in the dislocation structure of the parent plates. In macro-/mesoscale, the interfaces were outlined by a characteristic sharp transition indicating that there was no mechanical mixing between the welded metals in the solid state. In micro-/nanoscale, the layers adhering to the interface show typical deformed microstructure features, i.e., structure refinement, elongated dislocation cells, slip bands, and microtwins (in copper plate). The internal microstructure of the intermetallic inclusion is composed mostly of dendrites. The electron diffractions and TEM/EDX chemical composition measurements revealed three crystalline equilibrium phases of the γ-Al₄Cu₉, η-AlCu, and Θ-Al₂Cu type (the last one was dominant). However, most of the observed phases of the general Cu _m Al _n type (also crystalline) do not appear in the equilibrium Al-Cu phase diagram. Inside the intermetallic inclusions, no significant regularity in the phase distribution with respect to the parent sheets was observed. Therefore, it was concluded that the processes occurring in the melt determined their local chemical composition.     

Surface activity of mixtures of oxyethylated methyl dodecanoate and sodium dodecylbenzenesulfonate

Surface and interfacial tension and detergency of mixtures containing oxyethylated methyl dodecanoate and sodium dodecylbenzenesulfonate were determined. Synergism in the surface tension reduction was not observed. The competition for adsorption at the air/water interface between oxyethylated methyl dodecanoate and sodium dodecylbenzenesulfonate depended on the considered surface tension, the weight ratio of surfactants in the aqueous phase, and the hydrophile-lipophile balance of the nonionic surfactant. Generally, coverage of the interface with oxyethylated methyl dodecanoate increased when surface tension decreased. Nonionics were the dominant species at the interface in the important region of surface activity, i.e., for surface tensions below 40 mN m⁻¹. The mole fraction of the hydrophobic nonionic at the interface was higher than the contribution of hydrophilic oxyethylates. An increase of the surfactant ratio in the bulk phase affects the interfacial ratio of surfactants in the same way. The lowest interfacial tension (1.5 mN m⁻¹) at the hexadecane/water interface was observed for oxyethylated methyl dodecanoate having an average degree of oxyethylation equal to 8 and 10. Nearly 5 min was needed to achieve equilibrium value. Mixtures with sodium dodecylbenzenesulfonate decreased the interfacial tension somewhat less efficiently but the equilibrium was rapidly established. The standard washing powders containing oxyethylated methyl dodecanoates exhibited washing ability similar to that obtained for the powder with traditional alcohol oxyethylate.     

Electrical modeling of CIGS thin-film solar cells working in natural conditions

In the paper, results of electrical modeling of Cu(In_xGa_1−x)Se₂ (CIGS) thin-film photovoltaic (PV) modules are presented. Whether the equivalent double diode model—DEM (Double diode Equivalent Model) is appropriate to model CIGS PV modules was investigated. Modeling was based on large amount of data (including current-voltage (I-V) curves) collected during long-term outdoor monitoring of PV systems. The process of applying baseline physical parameters to two of five DEM parameters: diffusion I_S1 and recombination I_S2 related components of dark diode saturation current was carried out. Modeled I_S1 and I_S2 values were used to replace previously approximated DEM parameters and then to predict measured I-V curves in order to determine electrical parameters of the PV modules. The parameters are used to predict energy yield in natural operating conditions. Results of modeling are presented and compared with measured data.     

Carbonic inclusions on SiC/SiO2 interface investigated with Raman Scattering

Silicon carbide (SiC) is a wide band gap semiconductor suitable for high power and frequency electronic devices. The most important features of the material making it promising in this application are good thermal conductivity, high breakdown voltage and formation of native SiO₂ layer on the surface of SiC substrate by thermal oxidation. However, the material has significant drawbacks. The most important one is low surface mobility. The surface mobility of the charge carriers is decreased by near interface states (NIT's — Near Interface Traps) — caused by defects formed in the vicinity of SiC/SiO₂ interface. There are several candidates for NIT's and one of them is the occurrence of carbonic structures. Raman spectroscopy provides information about investigated structure without destruction of the sample. The aim of this work was to look for carbonic inclusions in 4H and 3C polytypes of SiC. The attention was focused on this part of the range of the Raman Shift where the strongest bands of carbonic structures are expected.     

The prospects for hard coal as a fuel for the Polish power sector

This paper presents the prospects for the development of the Polish hard coal sector from the perspective of the power sector. The most important issues determining the mid- and long-term future for domestic coal production are: (1) the development of the economy, hence the demand for electricity, (2) regulations (mostly environmental) affecting the power sector, (3) the competitiveness of coal-based technologies, and (4) the costs of domestic coal production. Since the range of issues and relations being considered is very broad, a specific method needs to be employed for the quantitative analysis. The tool applied in this study is the partial equilibrium model POWER-POL, in which both the coal and the power sectors are incorporated. The model focuses on energy–economy–environmental issues without capturing detailed macroeconomic links. The model was run under six scenario assumptions. The results show that the domestic coal sector should maintain its position as a key supplier of primary energy for the Polish power sector. However, the environmental regulations to which the domestic power sector has to conform will decrease the share of coal in the fuel-mix. Since the investment processes in this sector are usually long-term, the effects of changes will be noticeable from 2015 onwards.     

An Experimental Study and Numerical Modeling of the Flow in a Network of Triangular Microchannels

The flow characteristics of a network of parallel microchannels (hydraulic diameter: 110 μm) are investigated both experimentally and numerically. The microchannel cross-section was triangular, as in the case of microheat pipes. The pressure drop across the microchannel network showed a dramatic increase with a departure from the law of fully developed flow in ducts as soon as the Reynolds number of the flow exceeded about 10. Numerical computation of the flow was carried out using the classical laws of hydrodynamics in an attempt to explain this surprising result. There was a good agreement with experimental results, which suggests that there are no size effects at the length scales used in the experiments. Moreover, the mechanisms responsible for the large pressure drop for higher Reynolds numbers were identified in the numerical analysis as being extra head losses due to separation in several parts of the test section.     

Simulation of energy consumption in electrochemical grinding of hard-to-machine materials

The paper presents results of the simulation of the effect of some significant factors on energy consumption and specific energy consumption for electrochemical grinding and mechanical grinding of three hard-to-machine materials (sintered carbides B40, titanium alloy Ti6Al4V and steel 18G2A). The investigation has been carried out on models of energy consumption and specific energy consumption for electrochemical and mechanical grinding performed by the grinding wheel face. The results have shown that within the range of parameters and machining conditions employed, mechanical grinding of hard-to-machine materials is characterized by higher energy consumption than electrochemical grinding.