The morphological diversification of pollinia of some members of Asclepiadaceae

Most of the natural systems of plant classification have been based on exomorphic characters. The flower is a primary reproductive character considered to be more important than any vegetative characters. The mass of pollen grains is basically called pollinia. Like pollen, the pollinium is also the key character for the identification of specific plant species belonging to the family Asclepiadaceae (Dicotyledons) and Orchidaceae (Monocotyledons). Pollinial characters are now being used as important taxonomical tool for reassessing the different types of plant groups. The morphological nature of pollinia is specific in each genus. The morphological diversifications of pollinium of different genera of Asclepiadaceae were studied with the help of light microscope and phase contrast microscope (Leica-DM1000). The shape, size, position, orientation of pollinia, translator attachment, furrow position, etc are important criterion for the studies of pollinial morphology. This study analyzed the pollinial morphology of some selected plant taxa like Calotropis gigantea (L.) Ait., Daemia extensa R.Br., Dregea volubilis Benth, Gymnema sylvestre R.Br, Hoya globulosa Hook.f. and Tylophora indica (Burm.f.) Merr. collected from different parts of West Bengal.Key words: Asclepiadaceae, Orchidaceae, morphology, pollinia

Electrode materials for lithium-ion batteries and supercapacitors

University of Technology, Sydney. Faculty of Science.With the increasing demand for energy and growing concern about environmental pollution caused by the enormous consumption of fossil fuels, it is an urgent need of renewable energy and clean energy sources. Development of suitable mobile electronics or energy storage technologies that can be used in electric vehicles would help to address problem. As energy storage devices, lithium-ion batteries have attracted attention due to their high energy density and storage capacity. Supercapacitors have attracted enormous attention due to high power density and long cycle life. The exploration of new electrode materials for lithium-ion batteries and supercapacitors is the focus of research to satisfy the ever-rising demands for better performance including longer cycle life and improved safety. Nanostructured materials exhibit excellent electrochemical performances, and they are regarded as promising materials for high-performance lithium-ion batteries and supercapacitors. In this doctoral study, various nanostructured materials such as, nanosheets, nanospheres, nanobelts, nanoflakes, hybrid nanostructures and mesoporous structures have been successfully synthesized and characterised, using different methods. Their electrochemical properties have also been evaluated by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectra. Nickel oxide (NiO) nanosheets have been synthesized, using a simple ethylene glycol mediated hydrothermal method. When evaluated as anode materials for lithium ion batteries, NiO nanosheets exhibited high reversible capacities of 1193 mA h g⁻¹ at the current density of 500 mA g⁻¹ with enhanced rate capability and good cycling stability. While as electrode materials for supercapacitors, NiO nanosheets also demonstrated a superior specific capacitance of 999 F g⁻¹ at the current density of 20 A g⁻¹ with excellent cycling performance. The spherical β-Ni(OH)₂ superstructures was successfully synthesised in a single-step microwave-assisted process, without using any templates. Due to its unique morphology, the prepared β-Ni(OH)2 electrode displayed a high and specific capacitance of 2147 F g⁻¹ at a discharge current of 1 A g⁻¹ with excellent cycling stability (99.5 % capacitance retained after 2000 cycles). A straight forward microwave reaction was employed to successfully prepare α-Fe₂O₃ nanoparticles with two different sizes. When used as anode materials for lithium ion batteries of both the materials showed good electrochemical performances. Remarkably, the electrode made of larger particles (200-300 nm) exhibited higher reversible capacity of 1012 mA h g⁻¹ with better rate capability and excellent cycling stability (88 % retention after 80 cycles) than those of the smaller particles (20-30 nm) (49 % retention after 80 cycles). The better lithium storage properties of the large particles can be attributed to their structural integrity during cycling, which offers adequate spaces to accommodate volume expansion during Li⁺ insertion/extraction and shortens the diffusion paths of lithium ions. Highly porous NiCo₂O₄ nanoflakes and nanobelts were prepared in two steps; the NiCo₂O₄ intermediates were first formed by a hydrothermal method and the intermediates were simply thermal treated to the final product. Owing to their unique porous structural features, the NiCo₂O₄ nanoflakes and nanobelts exhibited high specific capacities of 1033 mA h g⁻¹ and 1056 mA h g⁻¹, respectively, good cycling stability and rate capability. These exceptional electrochemical performances could be attributed to the unique structure of high surface area and void spaces within the surface of nanoflakes and nanobelts, which provides large contact areas between electrolyte and active materials for electrolyte diffusion and cushions the volume change during charge-discharge cycling. Graphene/MnO₂ hybrid nanosheets were prepared by the incorporating graphene and MnO₂ nanosheets in ethylene glycol. As electrode materials for supercapacitors, graphene/MnO₂ hybrid nanosheets of different ratios were investigated. The graphene/MnO₂ hybrid nanosheets with a weight ratio of 1:4 (graphene: MnO₂) delivered the highest specific capacitance of 320 F g⁻¹, and exhibited good capacitance retention on 2000 cycles. Mesoporous NiCo₂O₄ nanosheets were synthesized by microwave method and applied as electrode materials for lithium ion batteries and supercapacitors. Due to its porous nanosheet structure, the NiCo₂O₄ electrodes exhibited a high reversible capacity of 891 mA h g⁻¹ at the current density of 100 mA g⁻¹ with good rate capability and stable cycling performance. When used as electrode materials for supercapacitors, NiCo₂O₄ nanosheets demonstrated a specific capacitance of 400 F g⁻¹ at the current density of 20 A g⁻¹ and superior cycling stability over 5000 cycles. The excellent electrochemical performance could be ascribed to the thin porous nanosheet structure, which provided high specific surface area to increase electrode-electrolyte contact area and facilitate rapid ion transport. Mesoporous flake-like Manganese-cobalt composite oxide (MnCo₂O₄) was successfully synthesized, using the hydrothermal method. The flake-like MnCo₂O₄ was evaluated as anode materials for lithium ion batteries. It exhibited superior rate capability and good cycling stability with a high reversible capacity of 1066 mA h g⁻¹. As electrode materials for supercapacitors, MnCo₂O₄ also demonstrated a high super capacitance of 1487 F g⁻¹ at the current density of 1 A g⁻¹ and superior cycling stability over 2000 charge-discharge cycles

Graphene-Based Planar Microsupercapacitors: Recent Advances and Future Challenges

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The continuous development of integrated electronics such as maintenance-free biosensors, remote and mobile environmental sensors, wearable personal electronics, nanorobotics etc. and their continued miniaturization has led to an increasing demand for miniaturized energy storage units. Microsupercapacitors with graphene electrodes hold great promise as miniaturized, integrated power sources thanks to their fast charge/discharge rates, superior power performance, and long cycling stability. In addition, planar interdigitated electrodes also have the capability to reduce ion diffusion distances leading to a greatly improved electrochemical performance. Either as standalone power sources or complementing energy harvesting units, it is expected that graphene-based microsupercapacitors will play a key role as miniaturized power sources in electronic microsystems. This review highlights the recent development, challenges, and perspectives in this area, with an emphasis on the link between material and geometry design of planar graphene-based electrodes and their electrochemical performance and integrability

Fabrication and enhanced electrochemical performances of Mo03/graphene composite as anode material for lithium-ion batteries

Molybdenum trioxide (Mo0#)/graphene composite were prepared by integrating Mo03 and graphene in dimethylformamide (DMF). The morphology and structure of the materials were characterized by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. The electrochemical properties of Mo03/graphene composite with different ratios were studied as anode materials for lithium-ion batteries using galavanostatic charge-discharge and cyclic voltammetry. We observed that the Mo03/graphene anode with a weight ratio of 1:1 (Mo03 graphene) exhibits a high lithium storage capacity of 967 mA h g-1 at the current density of 500 mA g-1, satisfactory cycling stability and good rate capability

A comparative investigation on the effects of nitrogen-doping into graphene on enhancing the electrochemical performance of SnO<inf>2</inf>/graphene for sodium-ion batteries

© 2015 The Royal Society of Chemistry. SnO2/nitrogen-doped graphene nanohybrids have been synthesized by an in situ hydrothermal method, during which the formation of SnO2 nanocrystals and nitrogen doping of graphene occur simultaneously. The as-prepared SnO2/nitrogen-doped graphene nanohybrids exhibit enhanced electrochemical performance for sodium-ion batteries compared to SnO2/graphene nanocomposites. A systematic comparison between SnO2/nitrogen-doped graphene nanohybrids and the SnO2/graphene counterpart as anode materials for sodium-ion batteries has been conducted. The comparison is in a reasonable framework, where SnO2/nitrogen-doped graphene nanohybrids and the SnO2/graphene counterpart have the same SnO2 ratio, similar SnO2 crystallinity and particle size, close surface area and pore size. The results clearly manifest that the improved electron transfer efficiency of SnO2/nitrogen-doped graphene due to nitrogen-doping plays a more important role than the increased electro-active sites within graphene network in enhancing the electro-activity of SnO2/nitrogen-doped graphene nanohybrids compared to the SnO2/graphene counterpart. In contrast to the previous reports which often ascribe the enhanced electro-activity of nitrogen-doped graphene based composites to two nitrogen-doping effects (improving the electron transfer efficiency and increasing electro-active sites within graphene networks) in one single declaration, this work is expected to provide more specific information for understanding the effects of nitrogen-doping into graphene on improving the electrochemical performance of graphene based composites

Adoption of Rational Farming Technology for Development of a Model for Exploring Sustainable Farming Practice in Farmer’s Field

The effectivity of Inhana Rational Farming (IRF) Technology was critically evaluated as a model of Sustainable Farming Practice in farmers’ field using okra (variety : Shakti - F1 hybrid) as test crop. The stusy was conducted at Binuria village in Birbhum District of West Bengal during February to October (2013). The village is in close vicinity of Visva Bharati University, Santiniketan. The study area lies in 23.660 N and 87.630E at about 179 ft. above MSL, with level to nearly level landscape. The experiment was laid down as per randomized block design (RBD) with 7 treatments replicated 3 times. The treatments included local farming practice with chemical inputs, organic farming practice (Inhana Rational Farming (IRF) Technology’ developed by Dr. P. Das Biswas, Founder, Inhana Biosciences, Kolkata) as well as integrated farming practice (combination of chemical and organic inputs for both soil and plant management). The most significant finding was that 100% reduction of chemical pesticide can be economically viable in the very first year with adoption of IRF Organic Package of Practice, under which 13.6% yield increase was recorded as compared to conventional farmer’s practice. Also when IRF was adopted for integrated cultivation model, higher yield as well as higher net income was obtained in comparison to conventional Farmer’s practice. Upto 144.5% higher Nitrogen Utilization efficiency and 32.8 % higher partial factor productivity was recorded under treatments with IRF Package. This higher response might be due to increased uptake and utilization of indigenous nutrients under the influence of high quality Novcom compost containing huge population (in order of 1016 c.f.u per gm moist compost) of self- generated microbes, which led to better nutrient (both macro and micro) mineralization in soil for plant uptake. This was also complimented by IRF Plant Management Package, which perhaps enhanced plant physiological functioning in terms of better N uptake and its utilization within plants

Case Report: “Spina Ventosa” Tuberculous Dactylitis in a 2 Year Old Boy - A Very Rare Disease

Tuberculous infection of metacarpals, metatarsals and phalanges is known as tuberculous dactylitis. There is a spindle shaped expansion of the short tubular bones due to tuberculous granuloma. Hence it is also known as spina ventosa. In our case, a two year old boy with a swelling in the metacarpal was provisionally diagnosed as enchondromata while the possibility of spina ventosa was kept in mind. He was posted for excision of the metacarpal followed by bone grafting. Histopathological examination report confirmed it as spina ventosa

Synthesis, antitubercular activity and mechanism of resistance of highly effective thiacetazone analogues

Defining the pharmacological target(s) of currently used drugs and developing new analogues with greater potency are both important aspects of the search for agents that are effective against drug-sensitive and drug-resistant Mycobacterium tuberculosis. Thiacetazone (TAC) is an anti-tubercular drug that was formerly used in conjunction with isoniazid, but removed from the antitubercular chemotherapeutic arsenal due to toxic side effects. However, several recent studies have linked the mechanisms of action of TAC to mycolic acid metabolism and TAC-derived analogues have shown increased potency against M. tuberculosis. To obtain new insights into the molecular mechanisms of TAC resistance, we isolated and analyzed 10 mutants of M. tuberculosis that were highly resistant to TAC. One strain was found to be mutated in the methyltransferase MmaA4 at Gly101, consistent with its lack of oxygenated mycolic acids. All remaining strains harbored missense mutations in either HadA (at Cys61) or HadC (at Val85, Lys157 or Thr123), which are components of the bhydroxyacyl-ACP dehydratase complex that participates in the mycolic acid elongation step. Separately, a library of 31 new TAC analogues was synthesized and evaluated against M. tuberculosis. Two of these compounds, 15 and 16, exhibited minimal inhibitory concentrations 10-fold lower than the parental molecule, and inhibited mycolic acid biosynthesis in a dose-dependent manner. Moreover, overexpression of HadAB HadBC or HadABC in M. tuberculosis led to high level resistance to these compounds, demonstrating that their mode of action is similar to that of TAC. In summary, this study uncovered new mutations associated with TAC resistance and also demonstrated that simple structural optimization of the TAC scaffold was possible and may lead to a new generation of TAC-derived drug candidates for the potential treatment of tuberculosis as mycolic acid inhibitors

Zeolite synthesis from low-cost materials and environmental applications: A review

Zeolites with the three-dimensional structures occur naturally or can be synthesized in the laboratory. Zeolites have versatile applications such as environmental remediation, catalytic activity, biotechnological application, gas sensing and medicinal applications. Although, naturally occurring zeolites are readily available, nowadays, more emphasis is given on the synthesis of the zeolites due to their easy synthesis in the pure form, better ion exchange capabilities and uniform in size. Recently, much attention has also been paid on how zeolite is being synthesized from low-cost material (e.g., rice husk), particularly, by resolving the major environmental issues. Hence, the main purpose of this review is to make an effective resolution of zeolite synthesis methods together with potential applications in environmental engineering. Among different synthesis methods, hydrothermal method is commonly found to be used widely in the synthesis of various zeolites from inexpensive raw materials such as fly ash, rice husk ash, blast furnace slag, municipal solid waste, paper sludge, lithium slag and kaolin. Besides, future expectation in the field of synthetic zeolites research is also included

An ACACB Variant Implicated in Diabetic Nephropathy Associates with Body Mass Index and Gene Expression in Obese Subjects

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