Dynamic behaviour of an adiabatic trickle bed reactor

Transient axial temperature profiles were measured in a laboratory adiabatic trickle bed reactor. Attention was paid to hot spot formation within the bed. The appearance of the hot spot temperature is a result of evaporation of the liquid reaction mixture. The motion of the hot spot temperature is caused by axial heat transfer resembles propagation of flame during combustion.     

Quantitative structure-property relationships of new benzoxazines and their electrooxidation as a model of metabolic degradation

The quantitative structure-property relationships study of 40 benzoxazines, that seem to be very promising antimycobacterial drugs, allowed proposing and testing of the equations describing effects of substituents on half-wave potentials of these compounds. Although two structural types of benzoxazines were studied (i.e. thioxobenzoxazinones and benzoxazinedithiones), it is possible to describe the effect of substituent on half-wave potentials of benzoxazines by one general equation. A good correlation for relationship between half-wave potential and energy of HOMO orbital was also found.The study of electrochemical oxidation of these compounds as a model of their possible metabolic degradation was performed. It was possible to propose general scheme of electrochemical oxidation of sulfur containing benzoxazine derivatives. From the metabolic point of view, desulfuration is the corresponding process to this pathway. As these derivatives were not examined in vivo, obtained results represent very beneficial clues, and, moreover, proposed scheme could serve as a support for the explanation of strong antimycobacterial activity of sulfur containing benzoxazines.     

Core/Shell PbSe/PbS QDs TiO2 Heterojunction Solar Cell

Quasi type‐II PbSe/PbS quantum dots (QDs) are employed in a solid state high efficiency QD/TiO₂ heterojunction solar cell. The QDs are deposited using layer‐by‐layer deposition on a half‐micrometer‐thick anatase TiO₂ nanosheet film with (001) exposed facets. Theoretical calculations show that the carriers in PbSe/PbS quasi type‐II QDs are delocalized over the entire core/shell structure, which results in better QD film conductivity compared to PbSe QDs. Moreover, PbS shell permits better stability and facile electron injection from the QDs to the TiO₂ nanosheets. To complete the electrical circuit of the solar cell, a Au film is evaporated as a back contact on top of the QDs. This PbSe/PbS QD/TiO₂ heterojunction solar cell produces a light to electric power conversion efficiency (η) of 4% with short circuit photocurrent (J_sc) of 17.3 mA/cm². This report demonstrates highly efficient core/shell near infrared QDs in a QD/TiO₂ heterojunction solar cell.     

Poly(carbyne)s via reductive C1 polymerization

C1 polymerizations enable the synthesis of densely functionalized, persubstituted polymers that are challenging to access using conventional methods. One class of C1 polymers are the poly(carbyne)s, which are unique in that they can adopt branched or linear structures, or combinations thereof. Herein, we report the synthesis of new poly(carbyne)s, including those that feature side chains with carbonyl‐containing functional groups. The polymers were obtained by exposing solutions of monomers outfitted with trihalomethyl or trimethyl orthoformate groups to metallic lithium, and reaction performance was improved when electron transfer agents (e.g. naphthalene) were included. The mechanisms of the polymerizations were also deconvoluted and found to depend on the monomer employed.     

The Agonist Action of Alkylphenols on TRPA1 Relates to Their Effects on Membrane Lipid Order: Implications for TRPA1-Mediated Chemosensation

The Transient Receptor Potential Ankyrin 1 cation channel (TRPA1) is a broadly-tuned chemosensor expressed in nociceptive neurons. Multiple TRPA1 agonists are chemically unrelated non-electrophilic compounds, for which the mechanisms of channel activation remain unknown. Here, we assess the hypothesis that such chemicals activate TRPA1 by inducing mechanical perturbations in the plasma membrane. We characterized the activation of mouse TRPA1 by non-electrophilic alkylphenols (APs) of different carbon chain lengths in the para position of the aromatic ring. Having discarded oxidative stress and the action of electrophilic mediators as activation mechanisms, we determined whether APs induce mechanical perturbations in the plasma membrane using dyes whose fluorescence properties change upon alteration of the lipid environment. APs activated TRPA1, with potency increasing with their lipophilicity. APs increased the generalized polarization of Laurdan fluorescence and the anisotropy of the fluorescence of 1,6-diphenyl-1,3,5-hexatriene (DPH), also according to their lipophilicity. Thus, the potency of APs for TRPA1 activation is an increasing function of their ability to induce lipid order and membrane rigidity. These results support the hypothesis that TRPA1 senses non-electrophilic compounds by detecting the mechanical alterations they produce in the plasma membrane. This may explain how structurally unrelated non-reactive compounds induce TRPA1 activation and support the role of TRPA1 as an unspecific sensor of potentially noxious compounds.     

Magneto-hydrodynamic mixing: A new technique for preparing carbomer hydrogels

Magnetohydrodynamic mixing was evaluated as an alternative to conventional high shear mixing (HSM) in the preparation of carbomer hydrogels containing 1.22 wt% Carbopol® 980 NF. Neutralization of the carbomer dispersion (pH = 2.74) with triethanolamine (TEA) enabled to adjust the pH of the mixture and tune the viscosity of the hydrogel. Using HSM, this approach was limited to 0.2 wt% TEA (pH = 3.83) as the gel became too viscous and the recirculation flow dropped from 12 to 0.3 m³/h. Magnetohydrodynamic mixing enabled to reach TEA concentrations up to 1.0 wt% (pH = 5.31). Apparent viscosity measurements on samples having 0.2 wt% TEA revealed lower viscosities for carbomer hydrogels prepared with HSM, that is, 6800 mPa s versus 8800 mPa for magneto-hydrodynamic mixing. Based on ¹H NMR evidence, this decrease in apparent viscosity was attributed to structural damage to the carbomer backbone in combination with mechanochemical degradation of the added TEA.     

Impact of German Energiewende on transmission lines in the central European region

This paper analyses the impacts of the growth of renewable energy production and German nuclear phase-out on the electricity transmission systems in Central Europe. The principal concern is the significant disparity between the growth of renewable production and the pace at which new transmission lines for the transport of electricity have been built, especially in Germany. This imbalance profoundly endangers the system stability and reliability in the whole region. The assessment of these impacts on the transmission grid is analysed by the direct current load flow model ELMOD. Two development scenarios for the year 2025 are evaluated by 3 representative weeks. The results illustrate the issue from three different perspectives. First, the distribution of loads in the grids is shown. Second, hourly patterns during particular weeks are analysed. Third, a geographical decomposition is made, and problematic regions are identified. The high solar or wind power generation decrease the periods of very low transmission load and increase the mid- and high load on the transmission lines. High solar feed-in has less detrimental impacts on the transmission grid than high wind feed-in. High wind feed-in burdens the transmission lines in the north-south direction in Germany and water-pump-storage areas in Austria.     

Learning data discretization via convex optimization

Discretization of continuous input functions into piecewise constant or piecewise linear approximations is needed in many mathematical modeling problems. It has been shown that choosing the length of the piecewise segments adaptively based on data samples leads to improved accuracy of the subsequent processing such as classification. Traditional approaches are often tied to a particular classification model which results in local greedy optimization of a criterion function. This paper proposes a technique for learning the discretization parameters along with the parameters of a decision function in a convex optimization of the true objective. The general formulation is applicable to a wide range of learning problems. Empirical evaluation demonstrates that the proposed convex algorithms yield models with fewer number of parameters with comparable or better accuracy than the existing methods.     

Lipid content and fatty acid composition of green algae Scenedesmus obliquus grown in a constant cell density apparatus

The lipids of alga Scenedesmus obliquus grown under controlled conditions were separated and fractionated by column and thin-layer chromatography, and fatty acid composition of each lipid component was studied by gas-liquid chromatography (GLC). Total lipids were 11.17%, and neutral lipid, glycolipid and phospholipid fractions were 7.24%, 2.45% and 1.48% on a dry weight basis, respectively. The major neutral lipids were diglycerides, triglycerides, free sterols, hydrocarbons and sterol esters. The glycolipids were: monogalactosyl diglyceride, digalactosyl diglyceride, esterified sterol glycoside, and sterol glycoside. The phospholipids included: phosphatidyl choline, phosphatidyl glycerol and phosphatidyl ethanolamine. Fourteen fatty acids were identified in the four lipid fractions by GLC. The main fatty acids were C18:2, C16:0, C18:3(alpha), C18:1, C16:3, C16:1, and C16:4. Total unsaturated fatty acid and essential fatty acid compositions of the total algal lipids were 80% and 38%, respectively.