A Four Quadrant Analog Multiplier Employing Single CDBA

The author proposes a new, fully-integrable four quadrant analog multiplier using a current differencing buffered amplifier (CDBA), a new universal active element. The use of CDBA in fully-integrated multiplier circuit design is attractive, since it simplifies the implementation and reduces the component count while maintaining good performance.     

Self-characterization of linear and nonlinear adaptive optics systems

We present methods used to determine the linear or nonlinear static response and the linear dynamic response of an adaptive optics (AO) system. This AO system consists of a nonlinear microelectromechanical systems deformable mirror (DM), a linear tip-tilt mirror (TTM), a control computer, and a Shack-Hartmann wavefront sensor. The system is modeled using a single-input-single-output structure to determine the one-dimensional transfer function of the dynamic response of the chain of system hardware. An AO system has been shown to be able to characterize its own response without additional instrumentation. Experimentally determined models are given for a TTM and a DM.     

Modelling and simulation of stamp-charged coke making by 2-D discrete element method

Coking of coal blends using high-volatile coals with poor caking properties can be achieved by densifying the coal prior to carbonisation. In stamp-charged coke making, the coal charge is compacted to one large cake before entering the coke oven. A coal cake density of approximately 80% of the coal solid density is needed to produce a high-quality coke. Also, sufficient mechanical strength is required when transferring the cake from the stamping machine to the oven. To gain insight into the densification process and cake structure a 2-dimensional computational model based on the discrete element method (DEM) was set up. The model was validated against force and displacement patterns from laboratory stamping tests. Stamper movement in response to cake properties could be reproduced. The approach also enables tracking of cake porosity, particle rearrangement, stress and strain rates, etc. This offers additional possibilities for studying the densification process and understanding mechanical strength development.     

Synthesis,characterisation and electrochemical investigation of phthalocyanines with pendant 4‐{2‐[2‐(4‐tert‐butylphenoxy)ethoxy]ethoxy} substituents

In this study, a novel metal‐free phthalocyanine and three metallophthalocyanines carrying four 2‐[2‐(4‐tert‐butylphenoxy)ethoxy groups on the periphery were prepared by cyclotetramerisation of a dinitrile derivative in the presence of the corresponding divalent metal salts [zinc(ii ), cobalt(ii ), copper(ii )]. These new phthalocyanine compounds have been characterised by infrared, ¹H and ¹³C nuclear magnetic resonance and electrospray mass spectroscopies and elemental analysis. The electrochemical properties of the metal‐free, zinc(ii ) and cobalt(ii ) phthalocyanines were investigated by cyclic voltammetry and differential pulse voltammetry methods. The cobalt complex showed a metal‐based reduction process, while the metal‐free and zinc(ii ) phthalocyanines showed ligand‐based electron transfer processes. It has been found that the absorption spectra substantially depend on concentration. It has been shown that these changes are attributable to the association of the phthalocyanine molecule. The number of molecules in the associates and the equilibrium constants for this association are determined.     

Nuclear AgNOR protein enhancement in nucleoplasms of peripheral blood lymphocytes of babies/children with down syndrome

Down syndrome (DS) is one of the most common chromosomal disorders. The factors contributing to the mental retardation together with other defects in this syndrome have not been fully explained. Individuals with DS have extra rRNA gene family since they carry an extra chromosome 21. The few reports available are on the relationship between the nucleolus organizer regions (NORs) and DS phenotype. The in vivo regulation of NORs expression on the extra chromosome 21 is not completely understood. Previous studies have shown that nucleoli of lymphocytes from infants (mostly neonates) with DS contain more in vivo and in vitro nucleolar AgNOR proteins when compared with healthy infants. The objective of this study is to compare the in vivo nuclear AgNOR protein level in nucleoplasms (also called as karyoplasm) of nonstimulated peripheral blood lymphocytes from babies/children with DS and healthy controls. Peripheral blood samples obtained from 20 babies/children with DS and 20 matched healthy controls were smeared on clean glass slides and then AgNOR staining was performed. The AgNOR protein level in nucleoplasms of lymphocytes from both groups was calculated using a computer program. Nearly 100 interphase nuclei per individual were analysed. Average nuclear AgNOR protein levels in nucleoplasms of lymphocytes from babies/children with DS were found to be significantly higher than those of the controls (P < 0.001). On the basis of our present results, we propose that the increase of nuclear AgNOR protein in in vivo conditions may contribute to the formation of DS phenotypes. Microsc. Res. Tech. 79:133–139, 2016. © 2016 Wiley Periodicals, Inc.     

Volatiles of Fresh and Commercial Sweet Red Pepper Pastes: Processing Methods and Microwave Assisted Extraction

Microwave-assisted hexane or water extraction was used to extract flavor compounds from fresh red pepper fruit and also from traditionally and industrially made pepper pastes. The composition of the volatile components from each extract was analyzed using comprehensive two-dimensional gas chromatography with time of flight mass spectrometry. In total, 79 compounds were determined including 15 alcohols, 14 terpenes, 13 aldehydes, 12 ketones, 7 fatty acids, 6 fatty acid esters, and 6 browning reaction products. The major common compounds of fresh pepper and the pastes were 2-pentanone, 3-hexanol, acetic acid, oleic acid, and linoleic acid. The compounds (E)-2-undecenal, farnesol, 2-pentadecyn-1-ol, linolenic acid, and squalene were found only in the fresh pepper samples. Browning reaction products were observed in both of the pastes. However, their concentration was much higher in the industrially made one. Microwave-assisted hexane extraction from the traditionally made pepper paste gave the highest number of volatiles. Many volatiles considered to possess pleasant aroma characteristics were observed only in the traditionally made paste.     

Effects of Different Denture Cleansers on the Tensile Bond Strength of Denture Liners

The effect of two denture cleansers (Polident® and Protefix®) on the tensile bond strength between four soft liner materials (Molloplast B®, Permaflex®, Sofreliner Tough Medium®, and GC Reline Soft®) and a conventional denture base resin was investigated. For each of the liner materials 35 test specimens were prepared according to test the requirements and assigned into seven groups (n = 5). Before tensile testing, five of the liner specimens were kept in water or soaked in two cleansing solutions during 2 and 7 d. Five other samples served as a control group subjected directly to tensile testing. The bond strength values were obtained using a universal testing machine and compared statistically. The type of failure was assessed visually. No significant difference was found between the groups for the tested conditions used (p > 0.05). The most frequent failure mode was cohesive for Molloplast and Permaflex specimens, adhesive for Sofreliner Tough Medium, and a mixed type of failure was observed for GC Reline Soft material.     

Comparative analysis of thermophilic immobilized biohydrogen production using packed materials of ceramic ring and pumice stone

Ceramic ring and pumice stone were used as a support matrix for the enhancement of biohydrogen production in immobilized cell culture systems. The reactors were continuously operated for the hydrogen fermentation using sucrose as the major carbon source at varying hydraulic retention times (HRT) as an important operational factor. In terms of volumetric hydrogen production, the best value was obtained with ceramic ring at 1.5 h HRT (2.98 l H₂/l/d), on the other hand, the pumice stone packed reactor resulted in 30% less volumetric hydrogen production (2.28 l H₂/l/d) at two fold longer retention time (HRT 3 h). It was demonstrated that volumetric hydrogen production with the immobilized bioreactor configurations was 6 fold better than the suspended culture bioreactor configuration (CSTR). Furthermore, up to 4 mol and 5 mol hydrogen yields per mole of sucrose used (which are 62.5% and 50% of the theoretical values) were achieved by pumice stone and ceramic ring packed reactors, respectively, whereas suspended culture system yielded only 0.5 mol H₂/mol sucrose.     

Direct-Charge-Transfer Pseudo-N-Path SC Circuit Insensitive to the Element Mismatch and Opamp Nonidealities

A novel pseudo-N-path switched-capacitor circuit is described. Its center frequency is insensitive to element mismatch as well as to the finite gain and bandwidth of the opamps used. In this new architecture, the charges from the input source to the output are not transferred by an opamp; rather the opamp is used only as a buffer. The performance of the circuit is superior to that of a regular pseudo-N-path structure.