Soil Chemical Analysis

A large body of work has been reported in the last 5 years on the development of lead-free piezoceramics in the quest to replace lead–zirconate–titanate (PZT) as the main material for electromechanical devices such as actuators, sensors, and transducers. In specific but narrow application ranges the new materials appear adequate, but are not yet suited to replace PZT on a broader basis. In this paper, general guidelines for the development of lead-free piezoelectric ceramics are presented. Suitable chemical elements are selected first on the basis of cost and toxicity as well as ionic polarizability. Different crystal structures with these elements are then considered based on simple concepts, and a variety of phase diagrams are described with attractive morphotropic phase boundaries, yielding good piezoelectric properties. Finally, lessons from density functional theory are reviewed and used to adjust our understanding based on the simpler concepts. Equipped with these guidelines ranging from atom to phase diagram, the current development stage in lead-free piezoceramics is then critically assessed.

Perspective on the Development of Lead-free Piezoceramics

Large-Scale Fabrication of Boron Nitride Nanosheets and Their Utilization in Polymeric Composites with Improved Thermal and Mechanical Properties

Single-phased ferroelectromagnet BiFeO3 ceramics with high resistivity were synthesized by a rapid liquid phase sintering technique. Saturated ferroelectric hysteresis loops were observed at room temperature in the ceramics sintered at 880 °C for 450 s. The spontaneous polarization, remnant polarization, and the coercive field are 8.9 μC/cm2, 4.0 μC/cm2, and 39 kV/cm, respectively, under an applied field of 100 kV/cm. It is proposed that the formation of Fe2+ and an oxygen deficiency leading to the higher leakage can be greatly suppressed by the very high heating rate, short sintering period, and liquid phase sintering technique. The latter was also found effective in increasing the density of the ceramics. The sintering technique developed in this work is expected to be useful in synthesizing other ceramics from multivalent or volatile starting materials.

Room-temperature saturated ferroelectric polarization in BiFeO3 ceramics synthesized by rapid liquid phase sintering

Novel gas sensors with high sensing properties, simultaneously operating at room temperature are considerably more attractive owing to their low power consumption, high security and long-term stability. Till date, zinc oxide (ZnO) as semiconducting metal oxide is considered as the promising resistive-type gas sensing material, but elevated operating temperature becomes the bottleneck of its extensive applications in the field of real-time gas monitoring, especially in flammable and explosive gas atmosphere. In this respect, worldwide efforts have been devoted to reducing the operating temperature by means of multiple methods In this communication, room-temperature gas sensing properties of ZnO based gas sensors are comprehensively reviewed. Much more attention is particularly paid to the effective strategies that create room-temperature gas sensing of ZnO based gas sensors, mainly including surface modification, additive doping and light activation. Finally, some perspectives for future investigation on room-temperature gas-sensing materials are discussed as well.

Room-temperature gas sensing of ZnO-based gas sensor: A review

Performance of Different Bio-stimulants on Vegetative, Floral, Tuber Yield and Prolonging Vase life Quality Parameters of Dahlia (Dahlia Variabilis L.)

The anisotropic bonding in layered materials crystallize to form different structure such as smooth films, nanotubes, and fullerene-like nanoparticles. Here, the growth of different microstructure of MoS 2 via chemical vapor deposition (CVD) method through controlled processing parameters is reported. Scanning electron microscopy and Raman spectroscopy ascertained the MoS 2 on insulating substrate (SiO 2 /Si). It was observed that poor sulfur environment and slow vapor flow were unable to induce complete transition from MoO 3 -x to MoS 2 and formed intermediate MoO 2 .The MoS 2 and MoO 2 /MoS 2 heterostructure were synthesized via single step. In addition, by adjustment of heating rate with temperature of centre zone and vapor flow, flower like structure of MoS 2 was achieved.

Growth of Different Microstructure of MoS 2 through Controlled Processing Parameters of Chemical Vapor Deposition Method

The quick and easy monitoring of heavy metals in drinking water is utmost important due to their harmful effects on human health. In this work, a GaN-based high-electron-mobility transistor (HEMT) sensor has been fabricated using optical lithography and explored as a prospective sensor for the determination of trace Pb2+ ions present in the water. Graphitic carbon nitride (g-C3N4) was synthesized by a single-step combustion method. The g-C3N4 nanosheets were used to functionalize the gate area of the fabricated GaN HEMT sensor to investigate the presence of Pb2+ metal ions in water. The g-C3N4 functionalized sensor exhibited a sensitivity of around $0.46 \mu \text{A}$ /ppb with 0.32 ppb, as the limit of detection (LoD) is much below the international set standards. Moreover, the real-time measurements on lake water were performed using the developed GaN HEMT sensor to detect the presence of Pb2+ ions in real samples in a fast and ultrasensitive manner. We anticipate that the reported work will certainly serve as a proof-of-concept to develop heavy metal ion sensors.

Ultrasensitive Real-Time Detection of Pb2+ Ions Using g-C3N4 Nanosheets

Resonance Raman scattering, a very effective and sensitive technique for atomically thin semiconducting transition metal dichalcogenide, can be used to observe the phonons from the entire Brillouin zone. In addition to the significance of resonance effect on the Raman spectrum it may also be used to probe the electron-phonon coupling. Our study is devoted to understand the phonons in layered MoS2, especially for very low frequency range (i.e. below 100 cm-1), as a function of temperature under the resonance effect. Understanding the phonon-phonon and electron-phonon coupling and the effects of temperature on the Raman spectrum are the central points of the present study. We observe the anomalous softening and broadening of a very low frequency phonon mode P3 (~34 cm-1) at low temperature ( i.e below 150 K). We attributed the observed anomalous trend in frequency and linewidth of this low frequency phonon to the electron-phonon coupling. Furthermore, our work also highlights the temperature induced tuning of resonance condition via understanding the intensity of phonon modes as a function of temperature.

Tunable Resonance and Electron-Phonon Coupling in Layered MoS2

Terminal heat stress (HS) reduces quantity and quality of grains. Wheat is highly sensitive to HS and there is a wide diversity among different genotypes for HS-tolerance. The enzymes associated with starch biosynthesis are severely affected by HS, especially starch synthases (SS). Different isoforms of SS have been reported from cereals viz. rice, maize, etc.; however, limited information is available in the wheat. In this study, we investigated the effect of HS on contrasting wheat (Triticum aestivum L.) cultivars — HD2985 (thermotolerant) and HD2329 (thermosusceptible) at grain-filling stage. Here we report the identification and cloning of three putative SS genes from wheat. The putative SS has been characterized in silico with other SS reported from different plant and non-plant sources in order to investigate potential functional and evolutionary relationships between SSs. The correlation between HS and SS activity and other biochemical parameters associated with thermotolerance in two cultivars was also studied. Three putative SS genes (transcript_7326, transcript_24546 and transcript_38472) were cloned from HD2985 cultivar under HS by data mining generated from whole transcriptome analysis. The sequences were in silico characterized and submitted in NCBI GenBank (accession nos. KM206143, KM206144 and KJ854903). Glucosyltransferase domain was observed in all the three sequences. Based on ClustalW alignment, SSs were classified into four distinct families. Expression analysis and SS activity assay showed significantly higher transcript level and SS activity during mealy-ripe stage than at milky-ripe stage in HS-treated HD2985, compared to HD2329 cultivar. Both the cultivars showed decrease in starch content under HS and the overall content was higher in HD2985, compared to HD2329. Similarly, guaiacol peroxidase, catalase, free amino acid and total antioxidant capacity were higher during mealy-ripe stage in HD2985. HS during milky-ripe had more severe impact on the overall physiochemical properties of wheat grain and thus needed to be targeted using different approaches in order to enhance the quality and yield of wheat under HS.

http://nopr.niscair.res.in/bitstream/123456789/41194/1/IJBB%2052%283%264%29%20254-266.pdf

Identification of novel starch synthase genes using de novo assembly and heat-induced expression and activity in developing wheat ( Triticum aestivum L.)

Mahesh Kumar

Papers

Performance of Different Bio-stimulants on Vegetative, Floral, Tuber Yield and Prolonging Vase life Quality Parameters of Dahlia (Dahlia Variabilis L.)

Growth of Different Microstructure of MoS 2 through Controlled Processing Parameters of Chemical Vapor Deposition Method

Ultrasensitive Real-Time Detection of Pb2+ Ions Using g-C3N4 Nanosheets

Tunable Resonance and Electron-Phonon Coupling in Layered MoS2

Identification of novel starch synthase genes using de novo assembly and heat-induced expression and activity in developing wheat ( Triticum aestivum L.)