Efficient and sensitive capacitive readout of nanomechanical resonator arrays

Here we describe all-electronic broadband motion detection in radio frequency nanomechanical resonators. Our technique relies upon the measurement of small motional capacitance changes using an LC impedance transformation network. We first demonstrate the technique on a single doubly clamped beam resonator with a side gate over a wide range of temperatures from 20 mK to 300 K. We then apply the technique to accomplish multiplexed readout of an array of individually addressable resonators, all embedded in a single high-frequency circuit. This technique may find use in a variety of applications ranging from ultrasensitive mass and force sensing to quantum information processing.     

Magnetic-aligned,magnetite-filled epoxy composites with enhanced thermal conductivity

This paper investigates the influence of magnetic field-assisted filler alignment technology on the morphology and the thermal conductivity of magnetite-filled epoxy composites. A magnetic field was applied during the solidification of the composite in order to change the position of the filler and its distribution in the polymer matrix. It is shown that the applied procedure leads to the filler being oriented along the direction of the magnetic field, and as a result, the thermal conductivity is improved by up to 120 % compared to a composite with randomly oriented filler obtained without the assistance of a magnetic field. This positive effect is caused by the appearance of conductive paths at a much lower content of the filler when the composite solidification is assisted by a magnetic field, relative to an equivalent isotropic sample. These morphological changes were confirmed by microscopic and X-ray microtomography imaging. The temperature dependences of thermal conductivity were also investigated over a broad temperature range for a magnetite-filled epoxy composite sample and compared to the bulk magnetite reference, showing that thermal behaviour of the magnetite-filled composite is stable, which is a promising result when considering the future application of the technology.     

Hot Corrosion of Ti–Re Alloys Fabricated by Selective Laser Melting

Selective laser melting (SLM) is an additive manufacturing process that enables novel alloy production by combining metals with significantly different physical properties. In this paper, the hot corrosion behavior of Ti–Re alloys fabricated by SLM was studied in a mixture of Na₂SO₄ and NaCl salts at 600 °C. The morphology and composition of the corrosion products were characterized by scanning electron microscopy with energy-dispersive X-ray spectroscopy and X-ray diffraction to understand the degradation mechanisms. It has been shown that the hot corrosion resistance of Ti–Re alloys was influenced by the chemical inhomogeneity of the oxide scale resulting from the presence of rhenium particles undissolved during the SLM process.     

Electronically controlled oscillator with linear frequency adjusting for four‐phase or differential quadrature output signal generation

This paper introduces novel four‐phase oscillator employing two Dual‐Output Controlled Gain Current Follower Buffered Amplifiers (DO‐CG‐CFBAs), single Current Amplifier, three resistors, and two grounded capacitors suitable for differential quadrature signal production (floating outputs). To control the frequency of oscillation (FO) and condition of oscillation (CO), only the current gain adjustment of active elements is used. The circuit was designed by well‐known state variable approach. The oscillator employs three active elements for linear control of FO and to adjust CO and provides low‐impedance voltage outputs. Furthermore, two straightforward ways of automatic amplitude gain control were used and compared. Active elements with very good performance are implemented to fulfill required features. Suitable CMOS implementation of introduced DO‐CG‐CFBA was shown. Important characteristics of the designed oscillator were verified experimentally and by PSpice simulations to confirm theoretical and expected presumptions. Copyright © 2013 John Wiley & Sons, Ltd.     

Effect of fuels and domestic heating appliance types on emission factors of selected organic pollutants

This study reports on the first complex data set of emission factors (EFs) of selected pollutants from combustion of five fuel types (lignite, bituminous coal, spruce, beech, and maize) in six different domestic heating appliances of various combustion designs. The effect of fuel as well as the effect of boiler type was studied. In total, 46 combustion runs were performed, during which numerous EFs were measured, including the EFs of particulate matter (PM), carbon monoxide, polyaromatic hydrocarbons (PAH), hexachlorobenzene (HxCBz), polychlorinated dibenzo-p-dioxins and furans (PCDD/F), etc. The highest EFs of nonchlorinated pollutants were measured for old-type boilers with over-fire and under-fire designs and with manual stoking and natural draft. Emissions of the above-mentioned pollutants from modern-type boilers (automatic, downdraft) were 10 times lower or more. The decisive factor for emission rate of nonchlorinated pollutants was the type of appliance; the type of fuel plays only a minor role. Emissions of chlorinated pollutants were proportional mainly to the chlorine content in fuel, but the type of appliance also influenced the rate of emissions significantly. Surprisingly, higher EFs of PCDD/F from combustion of chlorinated bituminous coal were observed for modern-type boilers (downdraft, automatic) than for old-type ones. On the other hand, when bituminous coal was burned, higher emissions of HxCBz were found for old-type boilers than for modern-type ones.     

Rhizosphere characteristics of the arsenic hyperaccumulator Pteris vittata L. and monitoring of phytoremoval efficiency

Recently discovered As-hyperaccumulator ferns hold promise for phytoremediation of As-polluted soils. We investigated changes in the rhizosphere characteristics of Pteris vittata (Chinese Brake fern) relevant for its use in phytoextraction. Plants were grown in rhizoboxes filled with soil containing 2270 mg kg(-1) As. Dissolved organic carbon (DOC) concentrations in rhizosphere soil solution were increased by 86% and appeared to enhance total Fe solubility due to complexation reactions. Despite substantial removal of As by the fern, As was not significantly decreased in the rhizsophere soil solution after one cropping, apparently due to the large buffer capacity of the soil and possibly because of ion competition with DOC. However, the difference between 0.05 M (NH4)2SO4-extractable labile As in bulk and rhizosphere soil accounted for 8.9% of total As accumulated in the fern, indicating that As was mainly acquired from less available pools. Moreover, As depletion in the rhizosphere and limited resupply from less available pools were indicated by a 19.3% decreased As flux, measured using the technique of diffusive gradients in thin films (DGT). Modeling of the DGT-soil system was able to show that the rate of release from solid phase to solution in the rhizosphere was one-third of that in the bulk soil. Applying the remedial strategy of bioavailable contaminant stripping, which aims at diminishing the phytoavailable pollutant fraction, DGT can be used as a monitoring tool to evaluate the efficiency of phytoextraction and to study the potential resupply of bioavailable pools after phytoextraction has ceased.     

Solar drying in sludge management in Turkey

Two main wastewater treatment plants in Bursa city in Turkey will start to operate and produce at least 27,000 tons of dry solids per year by the end of 2006. The purpose of this study was to investigate an economical solution to the sludge management problem that Bursa city would encounter. The general trend in Turkey is mechanical dewatering to obtain a dry solid (DS) content of 20%, and liming the mechanically dewatered sludge to reach the legal landfilling requirement, 35% DS content. This study recommends limited liming & solar drying as an alternative to only-liming the mechanically dewatered sludge. Open and covered solar sludge drying plants were constructed in pilot scale for experimental purposes. Dry solids and climatic conditions were constantly measured. Faecal coliform reduction was also monitored. The specially designed covered solar drying plant proved to be more efficient than the open plant in terms of drying and faecal coliform reduction. It was found that, if the limited liming & solar drying method was applied after mechanical dewatering instead of only-liming method, the total amount of the sludge to be disposed would be reduced by approximately 40%. This would lead to a reduction in the transportation, handling, and landfilling costs. The covered drying system would amortize itself in 4 years.     

Structure Prediction,Evaluation, and Validation of GPR18 Lipid Receptor Using Free Programs

The GPR18 receptor, often referred to as the N-arachidonylglycine receptor, although assigned (along with GPR55 and GPR119) to the new class A GPCR subfamily-lipid receptors, officially still has the status of a class A GPCR orphan. While its signaling pathways and biological significance have not yet been fully elucidated, increasing evidence points to the therapeutic potential of GPR18 in relation to immune, neurodegenerative, and cancer processes to name a few. Therefore, it is necessary to understand the interactions of potential ligands with the receptor and the influence of particular structural elements on their activity. Thus, given the lack of an experimentally solved structure, the goal of the present study was to obtain a homology model of the GPR18 receptor in the inactive state, meeting all requirements in terms of protein structure quality and recognition of active ligands. To increase the reliability and precision of the predictions, different contemporary protein structure prediction methods and software were used and compared herein. To test the usability of the resulting models, we optimized and compared the selected structures followed by the assessment of the ability to recognize known, active ligands. The stability of the predicted poses was then evaluated by means of molecular dynamics simulations. On the other hand, most of the best-ranking contemporary CADD software/platforms for its full usability require rather expensive licenses. To overcome this down-to-earth obstacle, the overarching goal of these studies was to test whether it is possible to perform the thorough CADD experiments with high scientific confidence while using only license-free/academic software and online platforms. The obtained results indicate that a wide range of freely available software and/or academic licenses allow us to carry out meaningful molecular modelling/docking studies.