Status,ecological services and management of aquatic weeds of floodplain wetlands in India: An overview

Floodplain wetlands of India are biologically rich and productive ecosystems that support unique aquatic flora and fauna. Covering an area of about 0.354 million ha, the floodplain wetlands are a major source of self‐recruiting small indigenous fish (SIF). They offer vast potential for both capture and culture‐based fisheries, securing livelihood and nutrition for a large section of the population. In addition to tremendous anthropogenic pressures and climatic variability, these resources have experienced a significant reduction in their geographical and areal extent. Aquatic macrophytes infestation in Indian floodplain wetlands is posing serious challenges to their ecological and economic functioning. Degradation and shrinkage of these important resources have been observed over the past few decades, attributable to the spread of aquatic weed infestation, warranting urgent attention in regard to their conservation and restoration to address their impending challenges. The present study compiled a total of 530 species under 103 families of aquatic macrophyte, representing four Indian states of the Ganga and Brahmaputra river basin. Among these 530 species, 85 species exhibit medicinal values and 30 species are edible, whereas some other species are used for basketry, cordage, fodder and as dye. Accordingly, the present study reviews the present status of the floodplain wetlands, their common aquatic weeds and their ecological services. It also synthesizes the latest knowledge and discusses the challenging issues of aquatic weed management and their control measures directed to the sustainable management of the aquatic resources.     

Low-Temperature Synthesis of 0.65 PbMg1/3Nb2/3O3–0.35PbTiO3 Ceramics

Nanocrystalline 0.65 PbMg_1/3Nb_2/3O₃–0.35PbTiO₃ powders were synthesized by citrate gel method. The gel was prepared using citrate (titanium and niobium) and nitrate (lead and magnesium) salts. The hard gel obtained after completion of the reaction was treated to get the desired phase. Thermal analysis of the gel was done to optimize the calcination temperature. The calcined powders were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The crystallite size and the effective strain were found to be 50 nm and 0.03584 N, respectively.     

Preparation and characterization of an enzyme electrode based on cholesterol esterase and cholesterol oxidase immobilized onto conducting polypyrrole films

Cholesterol esterase (ChEt) and cholesterol oxidase (ChOx) enzymes were entrapped within polypyrrole (PPy) films on a platinum disc electrode during electrochemical polymerization. The characteristics of the PPy/ChEt/ChOx enzyme electrode thus prepared were investigated as a function of the time, pH, temperature, and concentration of cholesteryl palmitate by a spectrophotometric method. PPy/ChEt/ChOx electrodes can be used for the estimation of cholesteryl palmitate concentrations from 1 to 8 mM, can be used least 10 times, and have a shelf life of about 1 month at 4–10°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3769–3773, 2004     

Comparison of Biocorrosion due to Desulfovibrio desulfuricans and Desulfotomaculum nigrificans Bacteria

One observes several species of sulfate-reducing bacteria in nature. Presence of these species in a media may cause microbial influenced corrosion (MIC) of materials differently. To investigate this aspect of MIC, corrosion tests were performed on three types of stainless steels. The tests were done in modified Baar’s media inoculated separately by the two species of SRB namely Desulfovibrio desulfuricans (DD) and Desulfotomaculum nigrificans (DN). Electrochemical and immersion tests were performed to assess the extent of uniform and localized corrosion of these steels. Biofilms formed on the corroded samples were analyzed for estimating various components of its extracellular polymeric substances. Hydrogenase enzyme of these bacteria was tested to determine its nature and activity. Higher degree of corrosivity was observed in case of media inoculated with DD as compared to DN. More active nature of hydrogenase enzyme, its location in the periplasmic phase in DD and higher fraction of carbohydrate in biofilm formed due to DD have been suggested to be responsible for higher degree of corrosivity caused by them.     

Mechanically strong shape memory polyurethane for water vapour permeable membranes

Water vapour permeable polymeric thin films possess significant importance in miscellaneous applications such as packaging, medical devices, controlled‐release systems, electronics and biosensors. In this work, a series of shape memory polyurethanes (SMPUs) were synthesized by a two‐step pre‐polymerization technique with variations in hard to soft segments and molecular weight of macroglycol. DSC, Fourier transform infrared spectra, dynamic TGA and tensile testing were carried out to characterize and evaluate the properties of these synthesized SMPUs. The effect of the soft segment and the molecular weight of macroglycol on the thermal properties, mechanical properties and water vapour permeability of the synthesized SMPUs were investigated to achieve a good water vapour permeable membrane. We found that the synthesized SMPUs demonstrated a good water vapour transmission rate of over 1460 g m^?2 day^–1 as well as robust mechanical properties with tensile strength 19.8 MPa indicating a promising permeable polymeric thin film for many potential applications, especially as protective clothing. © 2018 Society of Chemical Industry     

Mild Solution and Constrained Local Controllability of Semilinear Boundary Control Systems

The existence of mild solution and the constrained local controllability of a retarded boundary control system with nonlocal delay condition have been established. The theory of extrapolation spaces is applied to derive the mild solution. Then, the constrained local controllability is established using the generalized open mapping theorem. In the last section, application of the result is shown through examples of control systems represented by hyperbolic partial differential equations.     

Text box proposals for handwritten word spotting from documents

International Journal on Document Analysis and Recognition (IJDAR) - In this article, we propose a new approach to segmentation-free word spotting that is based on the combination of three...     

Rheological behavior of gel‐filled raw natural rubber and styrene‐butadiene rubber with reference to gel‐matrix intermixing

Natural rubber (NR) and styrene‐butadiene rubber (SBR) latex gels were prepared by sulfur prevulcanization technique with varying amounts of curing agent and accelerator systems to generate gradient in crosslink density. These gels were characterized by solvent swelling, dynamic light scattering, atomic force microscopy, and mechanical properties. Crosslinked NR gels were intermixed with neat SBR matrix and vice versa. Rheological behavior of chemically crosslinked gel‐filled NR and SBR was studied by capillary rheometry. Intermixing of crosslinked gels in the rubber matrices resulted in a considerable reduction in apparent shear viscosity and die swell values. This behavior was found to be dependent on several factors like gel concentration in the matrix, crosslink density of the gels, their size, and distribution. The effect of temperature on viscosity was studied extensively following the Arrhenious‐Eyring model. A shear rate‐temperature superposition mastercurve was constructed to predict the melt viscosities of the systems as a function of temperature. The change in die swell values was related to the change in first normal stress difference. The scanning electron photomicrographs of the extrudates revealed that presence of gels markedly improved the surface roughness of the raw rubbers. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Comparative study of the deformation modulus of rock masses—a reply to the comments received from Gokceoglu (2018)

Bulletin of Engineering Geology and the Environment - The deformation modulus of a rock mass (E m) is an important parameter in rock mechanics and engineering and its determination is a difficult...