Study on the mechanical properties,environmental effect,degradation characteristics and ionizing radiation effect on silk reinforced polypropylene/natural rubber composites

Natural silk fiber (20%) reinforced polypropylene (PP) composites were prepared by compression molding. Tensile strength, tensile modulus, bending strength, bending modulus, impact strength and hardness of the prepared composite were found 54.7 MPa, 1826.2 MPa, 58.3 MPa, 3750.7 MPa, 17.6 kJ/m² and 95 shore A, respectively. To improve the biodegradable character of the composite, natural rubber (NR) was blended (10%, 25%, 50% by weight) with PP. It was found that the mechanical properties of the composite decrease with increasing NR in PP (except IS which increased rather decreasing). Environmental effect on the composite and degradation in various media were investigated in this study. Gamma radiation was used to increase the mechanical properties of the prepared composites. Increase in TS and BS were maximum at 250 krad dose for silk fiber/PP, silk fiber/PP:NR (90:10), silk fiber/PP:NR (75:25) and silk fiber/PP:NR (50:50) composites.     

Photo-stability of rhodamine-B/montmorillonite nanopigments in polypropylene matrix

A rhodamine-B based nanopigment was developed as a colorant for polypropylene products. The cationic dye rhodamine-B was intercalated into Na⁺-montmorillonite (Cloisite Na⁺) in an acidic medium. The dye-intercalated montmorillonite was centrifuged, dried and milled to prepare the nanopigment particles before mixing with polypropylene. X-ray diffraction studies on the intercalates showed an increase in the basal spacing, thus confirming intercalation of the dye molecules within the nanostructures of the interlayer spaces. Thermo-gravimetric investigations suggested improved thermal stability of the intercalated dye. UV-exposure tests on colored polypropylene/nanopigment composites showed a significant improvement in the photo-stability compared to the polypropylene/dye samples.     

The effect of dispersed paint particles on the mechanical properties of rubber toughened polypropylene composites

The influence of dispersed paint particles on the mechanical properties of rubber toughened PP was investigated. The matrix was basically a hybrid of PP, rubber and talc. Model systems with spherical glass bead filled matrix were also studied to examine the effect of filler shape and size. Properties like tensile strength, strain at break, impact strength, and fracture toughness were influenced by the dispersed inclusions. Tensile strength at yield decreased linearly according to Piggott and Leinder's equation. Strain at break decreased more drastically with paint particles than glass beads, revealing that irregularly shaped particles offered greater stress concentrations. The tensile strength and strain at break were less influenced by the size of paint particles whereas a slight decrease in the modulus values was observed with decreasing particle size. Impact strength and fracture toughness also decreased with increasing filler fraction. Lack of stress transfer between filler and matrix aided in reduction of impact strength. Decrease in fracture toughness was influenced by volume replacement and constraints posed by fillers. The size of paint particles had little effect on the impact strength and fracture properties at the filler concentration levels used in this investigation.     

Electrostatic characterization and threshold voltage modeling of inversion type InGaAs gate-all-around MOSFET

Journal of Computational Electronics - This paper presents an analytical investigation of the electrostatic properties of a moderately doped symmetric gate-all-around nanowire MOSFET having InGaAs...     

Performance analysis of M‐APSK generalised spatial modulation with constellation reassignment

Generalised spatial modulation (GSM) is a recently developed multiple‐input multiple‐output (MIMO) technique aimed at improving data rates over conventional spatial modulation (SM) systems. However, for identical antenna array size and configurations (AASC), the bit error rate (BER) of GSM systems in comparison with SM systems is degraded. Recently, a GSM system with constellation reassignment (GSM‐CR) was proposed in order to improve the BER of traditional GSM systems. However, this study focused on M‐ary quadrature amplitude modulation (M‐QAM) schemes. The focus of this paper is the application of a circular constellations scheme, in particular, amplitude phase shift keying (APSK) modulation, to GSM and GSM‐CR systems. An analytical bound for the average BER of the proposed M‐APSK GSM and M‐APSK GSM‐CR systems over fading channels is derived. The accuracy of this bound is verified using Monte Carlo simulation results. A 4 × 4 16‐APSK GSM‐CR system achieves a gain of 2.5 dB at BER of 10^?5 over the traditional 16‐APSK GSM system with similar AASC. Similarly, a 6 × 4 32‐APSK GSM‐CR system achieves a gain of 2 dB at BER of 10^?5 over equivalent 32‐APSK GSM system.     

Atomic-layer-deposited silicon-nitride/SiO2 stack––a highly potential gate dielectrics for advanced CMOS technology

An extremely thin (2 monolayers) silicon nitride layer has been deposited on thermally grown SiO₂ by an atomic-layer-deposition (ALD) technique and used as gate dielectrics in metal–oxide–semiconductor (MOS) devices. The stack dielectrics having equivalent oxide thickness (T_eq=2.2 nm) efficiently reduce the boron diffusion from p⁺ poly-Si gate without the pile up of nitrogen atoms at the SiO₂/Si interface. The ALD silicon nitride is thermally stable and has very flat surface on SiO₂ especially in the thin (<0.5 nm) thickness region.An improvement has been obtained in the reliability of the ALD silicon-nitride/SiO₂ stack gate dielectrics compared with those of conventional SiO₂ dielectrics of identical thickness. An interesting feature of soft breakdown free phenomena has been observed only in the proposed stack gate dielectrics. Possible breakdown mechanisms are discussed and a model has been proposed based on the concept of localized physical damages which induce the formation of conductive filaments near both the poly-Si/SiO₂ and SiO₂/Si-substrate interfaces for the SiO₂ gate dielectrics and only near the SiO₂/Si-substrate interface for the stack gate dielectrics.Employing annealing in NH₃ at a moderate temperature of 550 °C after the ALD of silicon nitride on SiO₂, further reliability improvement has been achieved, which exhibits low bulk trap density and low trap generation rate in comparison with the stack dielectrics without NH₃ annealing.Because of the excellent thickness controllability and good electronic properties, the ALD silicon nitride on a thin gate oxide will fulfill the severe requirements for the ultrathin stack gate dielectrics for sub-0.1 μm complementary MOS (CMOS) transistors.     

Nonoclusters of iron prepared by different methods and analyzed by various spectroscopic techniques

Two different preparative methods for loading zeolites with zerovalent iron clusters are compared: in the first case Fe(CO)₅ is adsorbed by NaX zeolite at low temperatures and decomposed under vacuum conditions up to 673 K. The iron clusters inside the cages of the zeolite are investigated by ferromagnetic resonance and Mössbauer spectroscopy. The second case deals with a sample prepared by ion exchange of NaA zeolite by means of a calculated amount of ferrous ions followed by reduction under an excess of sodium vapor at 573 K. Here the iron clusters are analyzed by Mössbauer and magnetization measurements. In both cases cluster composition and cluster sizes are comparable. The clusters are termed “nanoclusters” because their diameter is in the nanometer range ( 2 nm). We propose using these clusters for Fischer-Tropsch reactions, and we have achieved promising preliminary results.     

Development of a bio-physicochemical technique for arsenic removal from groundwater

Oxidation of ferrous ions by iron-oxidizing bacteria facilitates adsorption of arsenic on iron and subsequent co-precipitation. Based on this technique, a novel treatment process has been developed and tested under field conditions for simultaneous iron and arsenic removal from groundwater. In this study, a biological fixed bed reactor containing coconut husk and subsequent layers of iron matrix, charcoal and sand filter combined the biological and physicochemical treatment processes in a single system. Experimental results showed that arsenic could be efficiently treated from initial concentration of 500 μg L^− 1 to residual (effluent) concentrations lower than 15 μg L^− 1. Simultaneous significant iron removal efficiency (over 95%) was also achieved. Microbial water quality examination confirmed absence of any contamination in the treated water. Simple and inexpensive construction using locally available materials, considerable treatment performance as well as ease of operation and maintenance present the developed system as a promising one.     

Strategic Water Resources Planning: A Case Study of Bangladesh

Many agrarian countries have heavily invested in large-scale water projects to promote their agricultural development. There have been, however, few attempts to devise strategic water resources planning accounting for the macroeconomic linkages ofagriculture. This article presents such a strategic water resourcesplanning framework for Bangladesh. First, a dynamic costminimization model is solved to compute the optimal investmentneeded in various water projects such that an agricultural growthtarget can be met. Next, the minimum cost solution is againderived accounting for the macroeconomic linkages of agriculture,which, under different macroeconomic scenarios, results innoticeably different policy implications for optimal waterplanning. These results suggest that the traditional sectoralapproaches of planning water investment projects are generallyinconsistent with the broader macroeconomic reality of Bangladesh.     

Is sedation-induced BOLD fMRI low-frequency fluctuation increase mediated by increased motion?

Object

Increases in low-frequency fluctuations (LFF, 0.01–0.1 Hz) of BOLD fMRI signal were observed during sedation and sleep. We tested the hypothesis that sedation-induced LFF increases may be mediated by increased head motion likely associated with these brain states.

Materials and Methods

Twenty healthy volunteers were scanned in resting-state baseline and (15 thereof) in midazolam sedation condition. After standard preprocessing, LFF power was computed from average time series from 14 ROIs representing 5 functional networks (visual, motor, auditory, default mode, dorsal attentional). We assessed the effects of sedation on LFF and indirect effects of head motion (mean relative displacement) using mediation analysis.

Results

Sedation increased LFF power with the indirect effect of motion on sedation-induced LFF significant for all networks. Global mean corrected data showed similar but weaker results: significant total effect for auditory, motor and visual; significant mediation for auditory and motor networks. Motion was strongly correlated with LFF even at baseline. Reported results were significant at p < 0.05.

Conclusion

The study confirms that conscious sedation induces LFF increase, but demonstrates that this effect is mediated by increased head motion. Hence, caution in design and interpretation is recommended for studies comparing subjects or conditions differently predisposing to head motion.