Development of Cutting Tool Through Superplastic Boronizing of Duplex Stainless Steel

In this study, a cutting tool is developed from duplex stainless steel (DSS) using the superplastic boronizing technique. The feasibility of the development process is studied, and the cutting performances of the cutting tool are evaluated and compared with commercially available carbide and high-speed steel (HSS) tools. The superplastically boronized (SPB) cutting tool yielded a dense boronized layer of 50.5 µm with a surface hardness of 3956 HV. A coefficient of friction value of 0.62 is obtained, which is lower than 1.02 and 0.8 of the carbide and HSS tools. When tested on an aluminum 6061 surface under dry condition, the SPB cutting tool is also able to produce turning finishing below 0.4 µm, beyond the travel distance of 3000 m, which is comparable to the carbide tool, but produces much better results than HSS tool. Through superplastic boronizing of DSS, it is possible to produce a high-quality metal-based cutting tool that is comparable to the conventional carbide tool.     

ZnO microstructures and nanostructures prepared by sol-gel hydrothermal technique

Zinc oxide (ZnO) is an emerging material in large area electronic applications such as thin-film solar cells and transistors. We report on the fabrication and characterization of ZnO microstructures and nanostructures. The ZnO microstructures and nanostructures have been synthesized using sol-gel immerse technique on oxidized silicon substrates. Different precursor's concentrations ranging from 0.0001 M to 0.01 M (M=molarity) using zinc nitrate hexahydrate [Zn(NO3)2. 6H2O] and hexamethylenetetramine [C6H12N4] were employed in the synthesis of the ZnO structures. The surface morphologies were examined using scanning electron microscope (SEM) and atomic force microscope (AFM). In order to investigate the structural properties, the ZnO microstructures and nanostructures were measured using X-ray diffractometer (XRD). The optical properties of the ZnO structures were measured using photoluminescence (PL) and ultraviolet-visible (UV-Vis) spectroscopies.     

Degradation of compressive properties of pultruded kenaf fiber reinforced composites after immersion in various solutions

In this paper, water absorption behavior of pultruded kenaf fiber reinforced unsaturated polyester composites was investigated. Residual compressive properties of the composites after immersion were also reported. Composites were prepared using pultrusion method with minimum kenaf fiber content of 70% w/w. Water absorption tests were performed at room temperature under three different solutions, i.e. distilled water, sea water and acidic solution. The diffusion coefficient of water absorption and maximum moisture content were calculated by measuring the water uptake of specimen at regular time interval. Diffusion coefficient and the highest moisture content values were recorded for composite immersed in distilled water followed by acidic solution and sea water. The water absorption of kenaf fiber reinforced unsaturated polyester composites was found to follow a Fickian’s behavior where it reach equilibrium. The compressive properties were found to decrease with the increase in the percentage of water uptake. The decay in compression properties is attributed to the plasticization of the fiber–matrix interface and swelling of the kenaf fiber.     

Synthesis and size dependent optical studies in CdSe quantum dots via inverse micelle technique

Cadmium selenide quantum dots (CdSe QDs) were successfully synthesized without using trioctylphosphine (TOP). The XRD pattern showed zinc-blend phase of the CdSe QDs. The absorption and PL spectra exhibit a strong blue shift as the QDs size decreases due to the quantum confinement effect. In addition, the quantum efficiency of CdSe QDs with TOP capping is higher than CdSe QDs with oleic acid capping. TEM image shows a spherical shape, compact and dense structure of CdSe QDs. A good agreement between the Tauc's model and experimentally measured absorption spectra of CdSe QDs is achieved. The FTIR peak at ～1712 cm^?1 spectra confirms the influence of oleic acid as a capping agent.     

Seismic Rotational Stability of Waterfront Retaining Wall Using Pseudodynamic Method

Design of waterfront retaining walls under seismic conditions is an important topic of research among the geotechnical engineering fraternity, and recently there have been studies in which the stability of rigid waterfront retaining walls has been assessed. However, an important aspect of seismic rotational stability of such walls is still missing from the literature archives. The present study shows the importance of rotational displacements for the design of the rigid waterfront retaining wall. Consideration has been made for the calculation of the hydrodynamic pressure as well as the seismic forces, both due to the seismic pressure and seismic wall inertia. These seismic forces have been calculated using the pseudodynamic approach. The free water condition has been considered in the analysis, and thus the hydrodynamic pressure has been considered to exist on the downstream face of the retaining wall as well, and a well-known expression approximating the effect of the inertia of the water due to the earthquake has been used for the estimation of this hydrodynamic pressure force. Simple expressions for the calculation of rotational displacement both during and after the earthquake have been proposed, and typical results have been obtained. It is observed that with an increase in the ratio of the water level to the total height of the wall from 0.50 to 1.00 the rotational displacement of the wall increases by about 110%. Similar trend of an increase in the value of the rotational displacement was observed for an increase in the values of the horizontal and vertical seismic acceleration coefficients. Also, the parametric study carried out in the analysis suggested that the rotational displacement is sensitive to other parameters such as the upstream water height, pore pressure ratio, soil, and wall friction angles. Due to nonavailability of the results in which rotational stability of the waterfront retaining wall under the seismic conditions has been studied, the results from the present analysis seem to bring out a unique approach.     

High‐Performance Low‐Power FFT Cores

Recently, the power consumption of integrated circuits has been attracting increasing attention. Many techniques have been studied to improve the power efficiency of digital signal processing units such as fast Fourier transform (FFT) processors, which are popularly employed in both traditional research fields, such as satellite communications, and thriving consumer electronics, such as wireless communications. This paper presents solutions based on parallel architectures for high throughput and power efficient FFT cores. Different combinations of hybrid low‐power techniques are exploited to reduce power consumption, such as multiplierless units which replace the complex multipliers in FFTs, low‐power commutators based on an advanced interconnection, and parallel‐pipelined architectures. A number of FFT cores are implemented and evaluated for their power/area performance. The results show that up to 38% and 55% power savings can be achieved by the proposed pipelined FFTs and parallel‐pipelined FFTs respectively, compared to the conventional pipelined FFT processor architectures.     

Nutritional and amino acid contents of differently treated Roselle (Hibiscus sabdariffa L.) seeds

The effects of sun-drying and boiling sun-drying on the nutritional composition of Roselle (Hibiscus sabdariffa L.) seeds, grown from Malaysia, were investigated. The treatments were raw freeze-dried Roselle seeds (RRS), sun dried Roselle seeds (DRS) and boiled sun-dried Roselle seeds (BRS). Protein, lipids and dietary fibre were found to be high in all the treatments. The seeds, regarded as by-product of Roselle processing had 57.3% moisture. Raw freeze-dried, sun dried and boiled sun-dried seeds contained 6.81%, 9.9% and 9.8% moisture; 35.4%, 33.5% and 30.6% protein; 27.2%, 22.1% and 29.6% lipids; 2.3%, 13.0% and 4.0% available carbohydrate; 25.5%, 18.3%, and 19.2% total dietary fibre; and 7.4%, 7.5% and 6.6% ash, respectively. The carbohydrate, protein, lipids and moisture of RRS were significantly different (p < 0.05) from DRS and BRS. The predominant minerals in Roselle seeds were potassium (99–109 mg/100 g), magnesium (26–28 mg/100 g) and calcium (24–31 mg/100 g). The total dietary fibre of the seeds was within the acceptable range, with soluble and insoluble fibre ratios ranging from 1.2 to 3.3. The study detected 17 essential and non-essential amino acids. The seeds were rich in lysine (14–15 g/100 g), arginine (30–35 g/100 g), leucine (15.4–18.6 g/100 g), phenylalanine (11–12 g/100 g) and glutamic acid (21–24 g/100 g). The study indicated that Roselle seeds may serve as a potential source of functional ingredients.     

The Intra- and Extra-Telomeric Role of TRF2 in the DNA Damage Response

Telomere repeat binding factor 2 (TRF2) has a well-known function at the telomeres, which acts to protect the telomere end from being recognized as a DNA break or from unwanted recombination. This protection mechanism prevents DNA instability from mutation and subsequent severe diseases caused by the changes in DNA, such as cancer. Since TRF2 actively inhibits the DNA damage response factors from recognizing the telomere end as a DNA break, many more studies have also shown its interactions outside of the telomeres. However, very little has been discovered on the mechanisms involved in these interactions. This review aims to discuss the known function of TRF2 and its interaction with the DNA damage response (DDR) factors at both telomeric and non-telomeric regions. In this review, we will summarize recent progress and findings on the interactions between TRF2 and DDR factors at telomeres and outside of telomeres.     

Influence of bias voltage on the optical and structural properties of nc-Si:H films grown by layer-by-layer (LBL) deposition technique

The effects of applying a positive bias of 25 to 100 V on the optical, structural and photoluminescence (PL) properties of hydrogenated nanocrystalline silicon (nc-Si:H) films produced by layer-by-layer (LBL) deposition technique has been studied. Optical characterization of the films has been obtained from UV-VIS-NIR spectroscopy measurements. Structural characterization has been performed using X-ray diffraction, micro-Raman spectroscopy and field emission scanning electron microscope (FESEM). PL spectroscopy technique has been used to investigate the PL properties of the films. In general, the films formed shows a mixed phase of silicon (Si) nanocrystallites embedded within an amorphous phase of the Si matrix. The crystalline volume fraction and grain size of the Si nanocrystallites have been shown to be strongly dependent on the applied bias voltage. High applied bias voltage enhances the growth rate of the films but reduces the refractive index and the optical energy gap of the films. Higher crystalline volume fraction of the films prepared at low bias voltages exhibits room temperature PL at around 1.8 eV (700 nm).