Bio-Synthesized Nanoparticles in Developing Plant Abiotic Stress Resilience: A New Boon for Sustainable Approach

Agriculture crop development and production may be hampered in the modern era because of the increasing prevalence of ecological problems around the world. In the last few centuries, plant and agrarian scientific experts have shown significant progress in promoting efficient and eco-friendly approaches for the green synthesis of nanoparticles (NPs), which are noteworthy due to their unique physio-biochemical features as well as their possible role and applications. They are thought to be powerful sensing molecules that regulate a wide range of significant physiological and biochemical processes in plants, from germination to senescence, as well as unique strategies for coping with changing environmental circumstances. This review highlights current knowledge on the plant extract-mediated synthesis of NPs, as well as their significance in reprogramming plant traits and ameliorating abiotic stresses. Nano particles-mediated modulation of phytohormone content in response to abiotic stress is also displayed. Additionally, the applications and limitations of green synthesized NPs in various scientific regimes have also been highlighted.     

Microstructure and electrochemical properties of melt-spun Nd_(0.8)Mg_(0.2)(Ni_(0.8)Co_(0.2))_(3.8) hydrogen storage alloy

The effects of rapid solidification on the microstructure and electrochemical properties of Nd0.8Mg0.2(Ni0.8Co0.2)3.8 alloy were systematically investigated.The microstructure of alloys was characterized by scanning electron microscopy(SEM),X-ray diffractometer(XRD) and transmission electron microscopy(TEM).It was found that the melt-spun Nd0.8Mg0.2(Ni0.8Co0.2)3.8 ribbons became thinner and the average grain size of the ribbons became smaller with increasing wheel speed.A fraction of amorphous phase was observed for the ribbons melt-spun at high wheel speed(≥20 m/s).Microstructural characterization revealed that two phases:(Nd,Mg)2(Ni,Co)7 main phase(Ce2Ni7 type structure) and NdNi5 second phase(CaCu5 type structure),existed in the samples in cast state and melt-spun.The cycle stability of the melt-spun alloys was significantly enhanced as compared with cast alloy,and the sample prepared at wheel speed of 20 m/s exhibited good comprehensive electrochemical properties.     

On comparison of experimental and calculated neutron energy flux spectra at miniature neutron source reactor (MNSR)

Neutron energy spectrum in Miniature Neutron Source Reactor (MNSR), called Pakistan Research Reactor (PARR-2), is measured employing threshold neutron activation detectors. The calculated neutron spectrum was obtained through modeling the core in detail in three-dimensions employing the transport theory based code WIMS-D/4 and the diffusion theory based code CITATION which was also used as pre-information in the adjustment procedure. A Number of threshold detectors in the form of thin foils are used for spectrum measurements. Gamma activity of irradiated foils was measured with the help of a gamma spectroscopic system consisting of a high efficiency HPGe detector and 8000 channels PC based multi-channel analyzer. STAYNL computer code supplied by International Atomic Energy Agency (IAEA) was used for neutron spectrum adjustment. The group cross-section values and their covariance matrices were derived from the data given in preprocessed cross section libraries in ENDF–6 format of IRDF-90/NMF-G. The comparison between theoretical and experimental work shows good agreement.     

A new route for the beneficiation of low grade calcareous phosphate rocks

The bulk of the world's phosphate reserves is located in sedimentary horizons that contain appreciable amounts of carbonate. During beneficiation of phosphate rocks, huge amounts of oversize phosphate rocks are rejected from crushers. This reject also mostly contains low tricalcium phosphate content and high carbonate content. In this work, various experiments have been carried out to reduce the carbonate content by leaching the ground phosphate rock with dilute formic acid solution in order to get marketable and industrially acceptable phosphate grades. By using this technique, the effect of formic acid concentration, reaction time, process temperature and liquid/solid ratio (vol./wt. basis) have been studied. It was found that upon treatment of the ground rock with formic acid, the P₂O₅ percent can be raised by up to 29% corresponding to a reduction of about 69% in the calcium carbonate content of the samples, depending on the reaction conditions as well as nature and size of the raw phosphate particles used for analysis.     

The effect of filler concentration on the electrical,thermal, and mechanical properties of carbon particle and carbon fiber‐reinforced poly(styrene‐co‐acrylonitrile) composites

Composite materials of poly (styrene‐co‐acrylonitrile) (luran) matrix with carbon fibers (CF)/carbon particles (CP) were prepared and their properties were evaluated. The mechanical and thermal properties of these composites were studied by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Although, by increasing the filler concentration no significant difference was found in melting and crystallization temperatures of the luran. The storage and tensile modulus of the composites increased linearly with filler concentration up to 40 wt % that was approximately three times higher than that of the virgin luran. There is a shift in glass transition temperature of the composite with increasing the filler concentration and the damping peak became flatter that indicated the effectiveness of the filler–matrix interaction. The volume resistivity and thermal conductivity (TC) of the composites were also measured. At a given carbon filler content the CF–Luran composites have much less volume resistivity as compared to CP–Luran composites. The decreased percolation threshold and volume resistivity in case of CF–Luran composites indicated that conductive paths existed in the composites. The conductive pathways were probably formed through interconnection of the carbon fillers. The volume resistivity was also decreased as a function of temperature. The thermal conductivity was increased linearly as a function of temperature with increasing filler concentration up to 40% of CF and CP. This increase was more profound in case of CF–Luran as compared to CP–Luran composites. This was owing to greater thermal networks of fibers as compared to particles. POLYM. COMPOS., 28:186–197, 2007. © 2007 Society of Plastics Engineers     

High performance thermoplastic composites: Study on the mechanical,thermal, and electrical resistivity properties of carbon fiber‐reinforced polyetheretherketone and polyethersulphone

High temperature processing thermoplastic polymers, polyetheretherketone (PEEK) and polyethersulphone (PES), were melt blended with carbon fibers (CFs) to make composites. These composites were investigated for their mechanical, thermal, and electrical properties. Mechanical properties that are expressed in terms of storage modulus, loss, and damping were enhanced with the addition of CFs. Thermal properties were determined by DSC and TGA. These methods help to understand the effects of fiber content and fiber–matrix adhesion in the composites. Composites were also tested for their electrical and thermal conductivity because CFs leave the composites thermally and electrically conductive. CFs enhanced the crystallinity of the PEEK appreciably that in turn influenced thermal conductivity, electrical resistivity, and the stiffness of PEEK/CF (composites of PEEK with CFs). PES/CF (composites of PES with CF) shows a different behavior due to the amorphous nature of PES. The work involves one filler and two different matrices, and so it provides an interesting comparison of how matrix morphology can influence the properties of composites. POLYM. COMPOS. 28:785–796, 2007. © 2007 Society of Plastics Engineers.