Circular RNAs in Acute Kidney Injury: Roles in Pathophysiology and Implications for Clinical Management

Acute kidney injury (AKI) is a common clinical condition, results in patient morbidity and mortality, and incurs considerable health care costs. Sepsis, ischaemia-reperfusion injury (IRI) and drug nephrotoxicity are the leading causes. Mounting evidence suggests that perturbations in circular RNAs (circRNAs) are observed in AKI of various aetiologies, and have pathogenic significance. Aberrant circRNA expressions can cause altered intracellular signalling, exaggerated oxidative stress, increased cellular apoptosis, excess inflammation, and tissue injury in AKI due to sepsis or IRI. While circRNAs are dysregulated in drug-induced AKI, their roles in pathogenesis are less well-characterised. CircRNAs also show potential for clinical application in diagnosis, prognostication, monitoring, and treatment. Prospective observational studies are needed to investigate the role of circRNAs in the clinical management of AKI, with special focus on the safety of therapeutic interventions targeting circRNAs and the avoidance of untoward off-target effects.     

Electrochemical hydrogenation of dinitrogen to ammonia on a polyaniline electrode

The fixation of molecular nitrogen (dinitrogen) to ammonia was investigated depending on applied potential, pressure and temperature on a Pt-plate coated with polyaniline (PAn) film in methanol/LiClO₄/H⁺ solution. The reaction product was only ammonia with a maximum concentration of ca. 57 μmol L⁻¹ after 5 h electrolysis time. Maximum current efficiency for ammonia formation was ca. 16%. The optimum film thickness was found to be 1.5 μm, N₂-pressure 50 bar and an optimum electrolysis potential was only −0.12 V (NHE).     

Comparison of cyclic fatigue resistance between different NiTi instruments with 4% taper

The aim of this study was to make a comparison between the cyclic fatigue (CF) resistance of F360, twisted files (TF), FlexMaster (FM) and RaCE instruments with 4% taper. A total of 40 instruments were evaluated 8 mm from the tip. A stainless steel block with a simulated canal of 1.5 mm diameter, and a 60° angle of curvature was tested using CF testing. One‐way ANOVA and posthoc Tukey's test (P < 0.05) were used. The F 360 files showed the highest CF resistance while the TF files had greater CF resistance than the FM and RaCE (P < 0.05). There was no significant difference between the FM and RaCE (P > 0.05). F360 instruments with a double S cross‐section had the highest CF resistance among the group. The TF led the NiTi rotary files to be more resistant to fatigue than the FM and RaCE instruments. Microsc. Res. Tech. 79:345–348, 2016. © 2016 Wiley Periodicals, Inc.     

Hydrogen evolution on conducting polymer electrodes in acidic media

Hydrogen evolution reaction (HER) was studied on polyaniline (PAn), polypyrrole (PPy) and on aniline/pyrrole (PAn–PPy) copolymer in acidic solutions. The cathodic Tafel slopes (b_c) and exchange current densities (j₀) were calculated from Tafel curves obtained in solutions of X M H₂SO₄ (X = 0.1, 0.2, 0.3, 0.4 and 0.5 M). Activation energies (E_a) were determined. The E_a-values were found to be ca. 26 for PAn, 36.5 for PPy, 40.6 for PAn–PPy and 20.6 kJ mol⁻¹for Pt.     

An investigation on worn surfaces of chopped glass fibre reinforced polyester through SEM observations

The wear mechanisms of chopped strand mat (CSM) glass fibre reinforced polyester (CGRP) composite subjected to dry sliding against smooth stainless steel counterface (R_a=0.06 μm) were studied using a pin-on-disc technique. The effects of normal load (30-90 N), sliding velocity (2.8-3.9 m/s) and sliding distance (0.7-3.5 km) on friction and wear behaviour of the CGRP composite in two different CSM orientations (parallel and anti-parallel) were measured. The worn surfaces of the CGRP composite specimens for each specific test condition were examined using scanning electron microscopy (SEM).Sliding in P-orientation exhibited lower friction coefficient at lower load and higher speed compared to AP-orientation. Meanwhile, sliding in AP-orientation exhibited (15%) less friction coefficient at higher load compared to P-orientation. At higher range of all tested parameters, AP-orientation exhibited less mass loss (16%) compared to the P-orientation.Interestingly, SEM observations showed various wear mechanisms that predominated by abrasive nature. Damage of different features in the matrix and CSM glass fibre associated with higher values of load, speed, and sliding distance such as micro- and macro-cracks in the matrix, interface separation, fibre debonding and fracture, and different sizes of fractured fibres were evident.     

Experimental investigation on ejector cooling system performance at low generator temperatures and a preliminary study on solar energy

In this paper, the performance of an ejector cooling system with constant-area mixing chamber was investigated at low generator temperatures. The cooling system was tested by using hot water as driving fluid and R123 as working fluid. The effects of operating temperatures on the cooling capacity and on the coefficient of performance (COP) of the system were experimentally investigated at an ejector area ratio of 7.17, which is suitable for solar cooling. As a result, COP of 0.42 was obtained at a vapor generator temperature of 74°C, evaporator temperature of 10°C, and at a critical condenser temperature of 29°C. A solar application of the system with single-glazed selective-type collectors in a horizontal position was conducted as a preliminary study. In the solar application, a cooling capacity of 1080 W for a 9.2 m² collection area at an evaporator temperature of 10°C was obtained.     

Determining the effect of process parameters on particle size in mechanical milling using the Taguchi method: Measurement and analysis

Micro and nano-particles have been successfully and widely applied in many industrial applications. The mechanical milling process is a popular technique used to produce micro and nano-particles. Therefore, it is very important to improve milling process efficiency and quality by determining the optimal milling parameters. In this study, the effects of the main mechanical milling parameters: milling time, process control agent (PCA), ball to powder ratio (BPR) and milling speed in the planetary ball milling of nanocrystalline Al 2024 powder were optimized by the Taguchi method. Mean particle size (d₅₀) was used to evaluate the effect of process parameters on the mechanical milling process. The orthogonal array experiment is conducted to economically obtain the response measurements. Analysis of variance (ANOVA) and main effect plot are used to determine the significant parameters and set the optimal level for each parameter. The as-received and milled powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and a laser particle size analyzer, respectively. The results indicate that the process control agent significantly affects (84% contribution) the mean particle size (d₅₀) while other parameters have a lower effect (16% contribution). The developed model can be used in the mechanical milling processes in order to determine the optimum milling parameters for minimum particle size.     

Influence of Tip Relief Modification on the Wear of Spur Gears with Asymmetric Teeth

Recently, spur gears with asymmetric teeth have been considered a way of increasing performance while maintaining the gearbox dimensions. Asymmetric teeth have different pressure angles on drive and coast sides. They provide, among other advantages, a high bending strength and low vibration. In spur gears with asymmetric teeth, wear has been observed to be a major failure mode. In this study, the impact of tip relief modification and pressure angle on the wear of spur gears with asymmetric teeth is numerically investigated. Here, the focus is on sliding wear. A wear model based on Archard's equation is employed to predict wear depth. The pressure angle and the tip relief are parameterized. In the analysis, instantaneous contact loads and Hertz pressures are used in wear depth calculations. It is shown that as the amount of the tip relief increases, the wear depth, particularly at the beginning and end of the mesh, decreases. As the number of wear cycles increases, the effect of the tip relief modification on wear depths decreases slightly. It was also shown that with an increase in tip relief, the dynamic load decreases. However, if the amount of tip relief modification increases excessively, the maximum dynamic load also increases. Therefore, an excessive increase in tip relief modification should be avoided, whereby the level of excessive increase depends on the tip relief configuration.     

The importance of air quality for underground spaces: An international survey of public attitudes

Space is a resource that is constantly being depleted, especially in mega-cities. Underground workspaces (UGS) are increasingly being included in urban plans and have emerged as an essential component of vertical cities. While progress had been made on the engineering aspects associated with the development of high-quality UGS, public attitudes toward UGS as work environments (ie, the public's design concerns with UGS) are relatively unknown. Here, we present the first large-scale study examining preferences and attitudes toward UGS, surveying close to 2000 participants from four cities in three continents (Singapore, Shanghai, London, and Montreal). Contrary to previous beliefs, air quality (and not lack of windows) is the major concern of prospective occupants. Windows, temperature, and lighting emerged as additional important building performance aspects for UGS. Early adopters (ie, individuals more willing to accept UGS and thus more likely to be the first occupants) across all cities prioritized air quality. Present results suggest that (perceived) air quality is a key building performance aspect for UGS that needs to be communicated to prospective occupants as this will improve their attitudes and views toward UGS. This study highlights the importance of indoor air quality for the public.     

Alkaline catalyzed biodiesel production from safflower (Carthamus tinctorius L.) oil: Optimization of parameters and determination of fuel properties

In this study, the process of biodiesel production from safflower oil was optimized using a single-stage alkaline catalyst (NaOH). The optimization process was carried out depending on parameters, such as catalyst concentration, methanol-oil ratio, reaction temperature, and reaction time. The optimum biodiesel conversion efficiency was obtained to be 93.4% at 0.5% catalyst concentration, 20% methanol-oil ratio, 60 min reaction time, and 60°C reaction temperature. The fuel properties of biodiesel obtained under optimal conditions were determined.