Influence of Solvent Polarity and Conditions on Extraction of Antioxidant,Flavonoids and Phenolic Content from A verrhoa bilimbi

This paper presents the influence of solvent polarity and extraction conditions on the extraction of total flavonoid, total phenolic and antioxidants from Averrhoa bilimbi. The experiment was performed using a different solvent at different extraction conditions, including extraction time （15-240 min）, temperature （30-70 ℃） and agitation speed （50-300 rpm）. Results showed that yields of extraction varies with solvent polarity. Extraction using 50% aqueous methanol gives the highest antioxidant activity and flavonoid content. The highest total flavonoid content （193.3 μg quercetin equivalent/g dry weight）, total phenolic content （717.8 μg gallic acid equivalent/g dry weight） and antioxidant activity （77%） was achieved using 50% methanol, at 70 ℃ and agitation speed of 300 rpm. This work may be useful for obtaining higher bioactive compounds during the extraction process of A. bilimbi.     

Selective formation of tungsten nanowires

We report on a process for fabricating self-aligned tungsten (W) nanowires with polycrystalline silicon core. Tungsten nanowires as thin as 10 nm were formed by utilizing polysilicon sidewall transfer technology followed by selective deposition of tungsten by chemical vapor deposition (CVD) using WF6 as the precursor. With selective CVD, the process is self-limiting whereby the tungsten formation is confined to the polysilicon regions; hence, the nanowires are formed without the need for lithography or for additional processing. The fabricated tungsten nanowires were observed to be perfectly aligned, showing 100% selectivity to polysilicon and can be made to be electrically isolated from one another. The electrical conductivity of the nanowires was characterized to determine the effect of its physical dimensions. The conductivity for the tungsten nanowires were found to be 40% higher when compared to doped polysilicon nanowires of similar dimensions.     

Electrochemical and microstructural characteristics of nanoperovskite oxides Ba0.2Sr0.8Co0.8Fe0.2O3−δ (BSCF) for solid oxide fuel cells

Nanoperovskite oxides, Ba_0.2Sr_0.8Co_0.8Fe_0.2O_3?δ (BSCF), were synthesized via the co-precipitation method using Ba, Sr, Co, and Fe nitrates as precursors. Next, half cells were fabricated by painting BSCF thin film on Sm_0.2Ce_0.8O_x (samarium doped ceria, SDC) electrolyte pellets. X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical impedance spectroscopy (EIS) measurements were carried out on the BSCF powders and pellets obtained after sintering at 900 °C. Investigations revealed that single-phase perovskites with cubic structure was obtained in this study. The impedance spectra for BSCF/SDC/BSCF cells were measured to obtain the interfacial area specific resistances (ASR) at several operating temperatures. The lowest values of ASR were found to be 0.19 Ω cm², 0.14 Ω cm² 0.10 cm², 0.09 Ω cm² and 0.07 Ω cm² at operating temperatures of 600 °C, 650 °C, 700 °C, 750 °C and 800 °C, respectively. The highest conductivity was found for cells sintered at 900 °C with an electrical conductivity of 153 S cm^?1 in air at operating temperature of 700 °C.     

Distribution of Alpha Thalassaemia Gene Variants in Diverse Ethnic Populations in Malaysia: Data from the Institute for Medical Research

Alpha thalassaemia is highly prevalent in the plural society of Malaysia and is a public health problem. Haematological and molecular data from 5016 unrelated patients referred from various hospitals to the Institute for Medical Research for α thalassaemia screening from 2007 to 2010 were retrieved. The aims of this retrospective analysis were to describe the distribution of various alpha thalassaemia alleles in different ethnic groups, along with their genotypic interactions, and to illustrate the haematological changes associated with each phenotype. Amongst the patients, 51.2% (n = 2567) were diagnosed with α thalassaemia. Of the 13 α thalassaemia determinants screened, eight different deletions and mutations were demonstrated: three double gene deletions, – – ^SEA, – – ^THAI, ––^FIL; two single-gene deletions, α–^3.7 and – α^4.2; and three non-deletion mutations, Cd59G > A (haemoglobin [Hb] Adana), Cd125T > C (Hb Quong Sze) and Cd142 (Hb Constant Spring). A high incidence of α–^3.7 deletion was observed in Malays, Indians, Sabahans, Sarawakians and Orang Asli people. However, the – – ^SEA deletion was the most common cause of alpha thalassaemia in Chinese, followed by the α–^3.7 deletion. As many as 27 genotypic interactions showed 1023 α thalassaemia silent carriers, 196 homozygous α⁺ thalassaemia traits, 973 heterozygous α⁰ thalassaemia carriers and 375 patients with Hb H disease. Statistical analysis showed a significant difference in the distribution of α thalassaemia determinants amongst the various ethnic groups. Hence, the heterogeneous distribution of common determinants indicated that the introduction of an ethnicity-targeted hierarchical α thalassaemia screening approach in this multi-ethnic Malaysian population would be effective.     

Application of common transformers faults diagnosis methods on biodegradable oil-filled transformers

Due to environmental concerns regarding the use of mineral oil, biodegradable oil is increasingly being used as an alternative dielectric fluid. This paper presents results of experiments performed in the laboratory on the use of biodegradable oils for transformer application. The investigations cover two important diagnostic techniques for insulation assessment: (i) an investigation of partial discharge (PD) activity and characteristics in such oils and (ii) an investigation of the standard hydrocarbon dissolved gas products produced due to transformer faults. The fundamental aim of the investigation was to provide information as to whether the existing analysis techniques of PD fault pattern recognition and dissolved gas analysis methods, developed for mineral oil, are valid when used for insulation assessment with biodegradable transformer oil. The experiments were conducted on test samples to simulate three common types of transformer faults: low-energy PDs, high-energy arcing/sparking, and overheating. For the purpose of comparison, the same tests were performed using a mineral oil (Shell Diala MX) and a biodegradable oil (Envirotemp FR3). Also, each oil type was tested at three different moisture levels and with or without the presence of solid insulating materials (pressboard). PD activity was monitored using the standard IEC60270 phase-resolved analysis method. The fault gases produced were extracted and analysed by standard gas chromatography methods. Test results indicate that the PD phase resolved patterns are, in general, similar for the two oil types and thus existing PD pattern interpretations can be used to distinguish different types of PD faults, e.g. corona versus surface discharges. However, the values of various discharge quantities (PD magnitudes, repetition rate, current, etc) are very different under the same test condition. The quantities and the trend of dissolved gases for faults in biodegradable oil are substantially different compared with mineral oil. For the PD fault, biodegradable oil was found to release only a limited number of gases. For arcing and overheating faults, the main key gas produced is different between the two oils. Also, the presence of cellulosic materials such as pressboard influences the extent of hydrocarbon gases dissolved in the oil. It was found that for biodegradable oil, fewer amounts of gases are produced as the oil gets wetter.     

Proposal of an alternating bending technique for evaluating low‐to‐high cycle fatigue of structural steels

This paper proposes an alternating bending technique for evaluating fatigue life in the low‐to‐high cycle fatigue regime. A method was developed for estimating the stress, elastic strain, and plastic strain ranges of a plastically deformed specimen subjected to alternating bending with consideration of stress and strain distributions. To evaluate its effectiveness, fatigue testing was conducted using a specimen made of a steel used for pressure vessels. The stress, elastic strain, and plastic strain ranges could be obtained during cyclic bending. The elastic strain amplitude life and plastic strain amplitude life curves were linear in a log–log plot in the low‐to‐high cycle fatigue regime. Hence, the fatigue life under alternating bending could be evaluated using the proposed strain‐based approach. However, these curves could not be predicted using equations with parameters obtained from tensile testing, such as the universal slope method, due to the strain gradient in the specimen.     

Design of polyurethane fibers: Relation between the spinning technique and the resulting fiber topology

Properties or characteristics of fibers are affected by their topology. In fact, these topologies are found to have significant impacts in the functionalities of many applications. Hence, in this study, the relations between the spinning techniques and the topology of the resulting fibers are studied with the aim to provide a guideline for future reference where fibers with certain topology can be fabricated to suit specific applications. For this purpose, polyurethane is chosen to be the raw material to fabricate the fibers due to its versatility to be applied in various fields. The surface morphology, structures, and alignments of the fibers are studied. It is found that the polymer solution properties largely influence the mechanisms in the spinning process and can significantly affect the topology of the fibers. For instance, viscous solutions enable the spinning of coiled and smooth fibers, whereas conductive solutions encourage the splaying of the solution jet which results in the spinning of straight fibers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47706.     

Work Function Tuning and Doping Optimization of 22-nm HKMG Raised SiGe/SiC Source–Drain FinFETs

The basic requirements on process design of extremely scaled devices involve appropriate work function and tight doping control due to their significant effect on the threshold voltage as well as other critical electrical parameters such as drive current and leakage. This paper presents a simulation study of 22-nm fin field-effect transistor (FinFET) performance based on various process design considerations including metal gate work function (WF), halo doping (N _halo), source/drain doping (N _sd), and substrate doping (N _sub). The simulations suggest that the n-type FinFET (nFinFET) operates effectively with lower metal gate WF while the p-type FinFET (pFinFET) operates effectively with high metal gate WF in 22-nm strained technology. Further investigation shows that the leakage reduces with increasing N _halo, decreasing N _sd, and increasing N _sub. Taguchi and Pareto analysis-of-variance approaches are applied using an L₂₇ orthogonal array combined with signal-to-noise ratio analysis to determine the best doping concentration combination for 22-nm FinFETs in terms of threshold voltage (V _t), saturation current (I _on), and off-state current (I _off). Since there is a tradeoff between I _on and I _off, the design with the nominal-is-best V _t characteristic is proposed, achieving nominal V _t of 0.259 V for the nFinFET and ?0.528 V for the pFinFET. Pareto analysis revealed N _halo and N _sub to be the dominant factor for nFinFET and pFinFET performance, respectively.     

Interfacial microstructure and shear strength of reactive air brazed oxygen transport membrane ceramic–metal alloy joints

To fabricate a multi-layered structure for maximizing oxygen production, oxygen transport membrane (OTM) ceramics need to be joined or sealed hermetically metal supports for interfacing with the peripheral components of the system. Therefore, in this study, Ag–10 wt% CuO was evaluated as an effective filler material for the reactive air brazing of dense Ce_0.9Gd_0.1O_2–δ–La_0.7Sr_0.3MnO_3±δ (GDC–LSM) OTM ceramics. Thermal decomposition in air and wetting behavior of the braze filler was performed. Reactive air brazing was performed at 1050 °C for 30 min in air to join GDC–LSM with four different commercially available high temperature-resistant metal alloys, such as Crofer 22 APU, Inconel 600, Fecralloy, and AISI 310S. The microstructure and elemental distribution of the ceramic-ceramic and ceramic-metal interfaces were examined from polished cross-sections. The mechanical shear strength at room temperature for the as-brazed and isothermally aged (800 °C for 24 h) joints of all the samples was compared. The results showed that the strength of the ceramic-ceramic joints was decreased marginally by aging; however, in the case of metal-ceramic joints, different decreases in strengths were observed according to the metal alloy used, which was explained based on the formation of different oxide layers at the interfaces.