Carbon-Supported KCoMoS2 for Alcohol Synthesis from Synthesis Gas

KCoMoS2 was supported on various carbon support materials to study the support effect on synthesis gas conversion. Next to two activated carbons with high micropore volume, a traditional alumina (γ-Al2O3) support and its carbon coated form (CCA) were studied for comparison. Coating alumina with carbon increases the selectivity to alcohols, but the AC-supported catalysts show even higher alcohol selectivities and yields, especially at higher temperatures where the conversions over the AC-supported catalysts increase more than those over the γ-Al2O3-based catalysts. Increasing acidity leads to decreased CO conversion yield of alcohols. The two activated-carbon-supported catalysts give the highest yield of ethanol at the highest conversion studied, which seems to be due to increased KCoMoS2 stacking and possibly to the presence of micropores and low amount of mesopores

A Numerical Study of Coulomb Interaction Effects on 2D Hopping Transport

We have extended our supercomputer-enabled Monte Carlo simulations of hopping transport in completely disordered 2D conductors to the case of substantial electron-electron Coulomb interaction. Such interaction may not only suppress the average value of hopping current, but also affect its fluctuations rather substantially. In particular, the spectral density $S_I (f)$ of current fluctuations exhibits, at sufficiently low frequencies, a $1/f$-like increase which approximately follows the Hooge scaling, even at vanishing temperature. At higher $f$, there is a crossover to a broad range of frequencies in which $S_I (f)$ is nearly constant, hence allowing characterization of the current noise by the effective Fano factor F\equiv S_I(f)/2e \left. For sufficiently large conductor samples and low temperatures, the Fano factor is suppressed below the Schottky value (F=1), scaling with the length $L$ of the conductor as $F = (L_c / L)^{\alpha}$. The exponent $\alpha$ is significantly affected by the Coulomb interaction effects, changing from $\alpha = 0.76 \pm 0.08$ when such effects are negligible to virtually unity when they are substantial. The scaling parameter $L_c$, interpreted as the average percolation cluster length along the electric field direction, scales as $L_c \propto E^{-(0.98 \pm 0.08)}$ when Coulomb interaction effects are negligible and $L_c \propto E^{-(1.26 \pm 0.15)}$ when such effects are substantial, in good agreement with estimates based on the theory of directed percolation.Comment: 19 pages, 7 figures. Fixed minor typos and updated reference

A Numerical Study of Transport and Shot Noise at 2D Hopping

We have used modern supercomputer facilities to carry out extensive Monte Carlo simulations of 2D hopping (at negligible Coulomb interaction) in conductors with the completely random distribution of localized sites in both space and energy, within a broad range of the applied electric field $E$ and temperature $T$, both within and beyond the variable-range hopping region. The calculated properties include not only dc current and statistics of localized site occupation and hop lengths, but also the current fluctuation spectrum. Within the calculation accuracy, the model does not exhibit $1/f$ noise, so that the low-frequency noise at low temperatures may be characterized by the Fano factor $F$. For sufficiently large samples, $F$ scales with conductor length $L$ as $(L_c/L)^{\alpha}$, where $\alpha=0.76\pm 0.08 < 1$, and parameter $L_c$ is interpreted as the average percolation cluster length. At relatively low $E$, the electric field dependence of parameter $L_c$ is compatible with the law $L_c\propto E^{-0.911}$ which follows from directed percolation theory arguments.Comment: 17 pages, 8 figures; Fixed minor typos and updated reference

Efficient Use of Corneal Grafts through Multimodal Donor Tissue Splitting

Background The reduced availability of corneal donor tissue in Ukraine requires the most effective use of the available grafts. The present work describes and evaluates a method to obtain several small diameter corneal grafts from a single donor cornea (multimodal donor tissue splitting). Material and Methods This retrospective cohort study includes keratoplasty procedures performed at the Department of Corneal Pathology, State Institution, The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine, Odessa, Ukraine. The method of graft preparation includes either lamellar dissection of the entire graft or partial lamellar dissection to obtain two lamellar and/or full-thickness grafts. Grafts were not only cut in a circular manner, but the individual shape was also adjusted to match the shape of non-circular corneal defects. Results A total of 324 keratoplasties between January 2016 and December 2017, using 270 grafts, were included. In 54 cases (including 34 emergency situations), one transplant was used for two recipients. Of these, 43 were therapeutic keratoplasties and 11 peripheral lamellar keratoplasties due to grade III-IV recurrent pterygia. In two cases, two grafts for one patient were dissected from a single donor cornea. Out of 43 patients with curative keratoplasty, visual acuity improved in 28 eyes (65.1%) or remained unchanged in 15 eyes (34.9%). Postoperative visual acuity was dependent on the initial state of the eye, the localisation, the depth and the area of the corneal defect. In eyes with peripheral corneal localisation of ulcerations, even in the presence of corneal perforation, good functional results were obtained. Conclusion If two or more grafts are obtained from a single donor cornea for different kinds of keratoplasty procedures, this reduces the need for corneal graft tissue and, consequently, the cost of preservation. Especially in regions with a high shortage of donor tissue, this provides additional tissue capacities for emergency situations

Activation of Tissue Reparative Processes by Glow-Type Plasma Discharges as an Integral Part of the Therapy of Decubital Ulcers

The results of a clinical study of the complex treatment of pressure ulcers using the method of activation of reparative processes in tissues by cold plasma discharges initiated by high-frequency current are presented. Activation was carried out with a specialized device generating cold plasma discharges at frequencies of 0.11, 2.64, and 6.78 MHz. It was shown that the process of activation in the skin and muscle tissues of the bedsore zone proceeds most efficiently when using a current with a frequency of 6.78 MHz as compared to currents with a frequency of 2.64 and 0.11 MHz. For a needle electrode with a diameter of 0.3 mm, the optimal exposure parameters were power—(5.0 ± 1.5) W and time—(2.0–3.0) s. The results of the analysis of histological samples, histochemical, and bacteriological analysis confirmed the effect and showed the dynamics of the process of activation of reparative processes in the tissues of the bedsore wound under the influence of cold plasma discharges and a decrease in microbial contamination. The most pronounced effect of activation was formed during the period from 14 to 21 days. The effectiveness of therapy by the method of activation of reparative processes with cold plasma discharges, according to the criterion of the rate of wound healing, ranged from 14 to 16%, depending on the etiology of the decubitus wound. It is concluded that the activation of tissue reparative processes by glow-type plasma discharges as an integral part of the treatment of decubital ulcers is an effective link in the complex treatment of pressure sores

Activation of Tissue Reparative Processes by Glow-Type Plasma Discharges as an Integral Part of the Therapy of Decubital Ulcers

The results of a clinical study of the complex treatment of pressure ulcers using the method of activation of reparative processes in tissues by cold plasma discharges initiated by high-frequency current are presented. Activation was carried out with a specialized device generating cold plasma discharges at frequencies of 0.11, 2.64, and 6.78 MHz. It was shown that the process of activation in the skin and muscle tissues of the bedsore zone proceeds most efficiently when using a current with a frequency of 6.78 MHz as compared to currents with a frequency of 2.64 and 0.11 MHz. For a needle electrode with a diameter of 0.3 mm, the optimal exposure parameters were power&mdash;(5.0 &plusmn; 1.5) W and time&mdash;(2.0&ndash;3.0) s. The results of the analysis of histological samples, histochemical, and bacteriological analysis confirmed the effect and showed the dynamics of the process of activation of reparative processes in the tissues of the bedsore wound under the influence of cold plasma discharges and a decrease in microbial contamination. The most pronounced effect of activation was formed during the period from 14 to 21 days. The effectiveness of therapy by the method of activation of reparative processes with cold plasma discharges, according to the criterion of the rate of wound healing, ranged from 14 to 16%, depending on the etiology of the decubitus wound. It is concluded that the activation of tissue reparative processes by glow-type plasma discharges as an integral part of the treatment of decubital ulcers is an effective link in the complex treatment of pressure sores