Post renal transplantation infections are a huge cause of concern for transplant physicians. Along with UTI, diarrhea causes the greatest number of infectious episodes in post-transplant period with huge morbidity and mortality more so in high-risk cases. Varied causes of diarrhea can be encountered in these patients; infections and drugs being most common. As their immunocompromised status already exposes them to repeated infections, detailed microbial pattern might help us to use antimicrobials more judiciously.

Sintered boron carbide is an extremely hard, structural ceramic material and it is difficult to be machined with conventional techniques. To overcome the machining problem, the spark plasma sintered (SPS) monolithic boron carbide (B4C) was successfully machined by wire electrical discharge machining (WEDM) as the material is electrically conductive. The effects of five different machining parameters of WEDM were carefully observed to check their effect on the useful responses, namely machining speed and surface roughness (Ra) for cutting sintered B4C samples. A number of experimental operations were derived by using the concept of central composite design (CCD) and fuzzy logic was implemented to predict the response for a particular input parameter set. Also, a multi objective optimization was performed by fuzzy logic rule based multi performance characteristics indices technique (MPCI).

Boron carbide powder was hot-pressed at 2070 °C with 30 MPa uniaxial pressure and 90 min soaking. The mechanical, microstructure and other related properties were evaluated. XRD of the boron carbide powder and sintered samples, shows the presence of B13C2 phase of high electrical conductivity. Crystal lattice parameters, space group, cell angle, cell parameters, etc. were found from Rietveld refinement. The micro Vicker's hardness was 26.98 ± 0.98 GPa at 4.9 N load, fracture toughness 3.54 ± 0.26 MPa m and Young's modulus 461.50 ± 4.5 GPa. The hot-pressed boron carbide was found to be electrically conducting, which can be machined using a wire electrical discharge machine (WEDM).

Polyamines (PA) have multifarious roles in plant-environment interaction and stress responses. In conjunction with GABA shunt, they regulate induction of tolerance under salinity stress in plants. Here, we tested the hypothesis that silicon improves salt tolerance through mediating vital metabolic pathways rather than acting as a mere mechanical barrier. Seedlings of two rice (Oryza sativa L.) cultivars MTU 1010 (salt-sensitive) & Nonabokra (salt-tolerant) growing in hydroponic culture were treated with NaCl (0, 25, 50 & 100 mM) combined with or without Si (2 mM). NaCl stress enhanced PA synthesizing enzymes activity and PA production in salt tolerant cultivar Nonabokra, whereas in the sensitive cultivar, MTU 1010 both declined. Enhanced activities of GABA synthesizing enzymes along with a decline in the activities of GABA degrading enzymes under NaCl exposure led to GABA accumulation in both the cultivars. The interactive effects of silicon and NaCl also induced the activities of the enzymes related to polyamine biosynthesis and inhibited polyamine degrading enzymes that enhanced PA contents in the cultivars. Supplemental Si decreased endogenous GABA levels by modulating GABA metabolising enzymes under NaCl stress. On the basis of all tested parameters cv. MTU 1010 was proven to be more responsive towards silicon application than cv. Nonabokra. Such study of silicon-induced polyamine accretion and reduced GABA accumulation may lower oxidative damage in rice cultivars under NaCl stress and thereby form a successful strategy to boost tolerance.

Unconventional wire electrical discharge machining (WEDM) process is successfully used to cut different metals, alloys, composites and recent addition is engineered ceramics which possess sufficient electrical conductivity. Boron carbide is one of the hardest ceramic materials that unable to be processed with conventional machine tools and can be machined by WEDM compulsorily with proper selection of machine parameters. This study is based on boron carbide samples which were prepared using spark plasma sintering (SPS) furnace and machined with WEDM. Five machining parameters were analyzed such as pulse on time, pulse off time, peak current, water pressure and servo feed rate. Surface roughness (Ra) and machining speed were considered as output parameters and design of experiment was derived using central composite design (CCD) of response surface method (RSM) with 32 numbers of different test runs. Adaptive neuro-fuzzy inference system (ANFIS) was used with a new set of 16 numbers of experiments to predict results and seen to be more reliable than predicted results of response surface method.

Polyamines (PAs) are positively charged amines which play diverse roles in mediating stress tolerance in plants. Abiotic stresses like salt, drought, temperature, heavy metals, etc., all induce oxidative damage in susceptible plants species. PAs ameliorate this damage by scavenging the toxic reactive oxygen species. PAs also recharge the antioxidant machinery by increasing the endogenous contents of compatible solutes like proline. PAs interact with crucial plant growth regulators to modulate the entire signaling response during abiotic stress. This chapter concisely presents the diverse functions of PAs in generating plant tolerance under suboptimal conditions.

The objective of the present investigation was to consider the effectiveness of exogenous silicate supplementation in reviving the arsenate imposed alterations on pigment content, Hill activity, photosynthetic parameters, sugar metabolism, polyamine, and ion contents in wheat (Triticum aestivum L. cv. PBW-343) seedlings. Experiments were conducted under different levels of arsenate (0, 25 μM, 50 μM, and 100 μM) in combination with silicate (0, 5 mM) in a hydroponic environment with modified Hoagland's solution for 21 days to determine the ameliorative role of silicon (Si). Arsenate exposure led to a decline in chlorophyll content by 28% and Hill activity by 30% on an average along with photosynthetic parameters. Activity of starch phosphorylase increased causing a subsequent decrease in starch contents by 26%. Degradation of starch enhanced sugar contents by 61% in the test cultivar. Dose-dependant increments in the activities of carbohydrate metabolizing enzymes viz., sucrose synthase, sucrose phosphate synthase, and acid invertase were also noted. Putrescine content was significantly enhanced along with a consequent decline in spermidine and spermine contents. The macro- and micronutrient contents declined proportionally with arsenate imposition. Conversely, silicate amendments irrespective of all arsenate concentrations brought about considerable alterations in all parameters tested with respect to arsenate treatment alone. Marked improvement in pigment content and Hill activity also improved the gas exchange parameters. Soluble sugar contents decreased and starch contents were enhanced. Increase in polyamine contents improved the ionic balance in the test cultivar as well. This study highlights the potentiality of silicon in ameliorating the ecotoxicological risks associated with arsenic pollution and the probable ability of silicon to offer an approach in mitigating arsenate-induced stress leading to restoration of growth and metabolism in wheat seedlings.

Electrical conductivity is an essential property for machining of sintered boron carbide especially by wire electrical discharge machining (WEDM) process. Pure boron carbide was spark plasma sintered to full density at 2050 degrees C. Rietveld refinement on XRD analysis confirmed presence of B13C2 as the major phase in the powder as well as in the sintered samples.Electrical conductivity was found to be similar to 48 Omega(-1) m(-1). The sintered specimens were successfully machined using WEDM technique. The microstructure of powder, machined and fractured surfaces of the sintered boron carbide were analyzed. At low power of WEDM with pulse current less than 140 A formation of molten, oxidized phases of boron carbide was observed as well as the development of surface cracks were minimum on the machined surface. Thus this work is aiming at achieving better product quality with sintered boron carbide specimens which are machined by WEDM.

We intended to investigate the response of arsenate on nitrogen metabolism in wheat seedlings and aimed to assess the efficacy of silicon amendments in modulating the metabolic disturbances caused by arsenate stress. The nitrogen metabolism of wheat cultivated in different levels of arsenate with or without silicate in a medium supplemented with modified Hoagland’s solution for 21 days was studied. Experimental design was completely randomized with different arsenate concentrations (0, 25, 50 and 100 μM) with or without 5 mM silicate. Arsenate treatment decreased growth along with decline in nitrate (NO3−) uptake and accumulation. Activities of nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS) as well as glutamate synthase (GOGAT) were lowered in the test seedlings. Decline in nitrite (NO2−) and amino acid contents were also evident along with an enhancement in the accumulation of toxic ammonia. Silicate supplementation under arsenate stress however, improved growth, repaired the arsenate-induced effects leading to an enhancement in nitrate (NO3−) uptake and consequently improved nitrite (NO2−) and amino acid contents as well. The total and soluble nitrogen contents were enhanced along with enhancements in activities of enzymes associated with nitrate metabolism while ammonia accumulation was lowered. Results therefore, imply the involvement of exogenous silicon amendments in relieving the metabolic alterations in nitrogen metabolism caused by arsenate stress that enabled wheat seedlings to adapt under arsenate excess and eventually promoted plant growth.

The metalloid arsenic (As) is considered to be biologically non-essential and major environmental concern to all organisms. The aim of our study was to evaluate whether silicon (Si) has ameliorative effects on growth, respiratory cycle and Gamma-Aminobutyric acid (GABA) synthesis in wheat (Triticum aestivum L. cv PBW 343) seedlings under arsenic stress. The experiments were performed in a completely randomized design with three repeats and two replicates for each treatment. The seedlings were subjected to different doses of arsenate As (V) (25, 50 and 100 mu M) with or without silicate (5 mM) in modified Hoagland's nutrient media for 21 days. Arsenate stress decreased seedling growth, activities of respiratory cycle enzymes particularly dehydrogenases while enhanced the levels of oxidative stress markers, Krebs cycle intermediates and GABA including activities of enzymes associated with GABA synthesis. Arsenate treatment disturbed the phosphate contents and impaired the respiratory process. Irrespective of arsenate concentrations, silicate administration substantially modulated the toxic effects of the metalloid in the test cultivar. Thus, silicon supplementation may emerge as a beneficial strategy to reduce potential health risks and might help to mitigate arsenic- induced stress in wheat seedlings. (C) 2018 SAAB. Published by Elsevier B.V. All rights reserved.

Silicon is widely available in soil and is known to mitigate both biotic and abiotic stress in plants. Very low doses of silicon are becoming increasingly essential in rice for biofortification and preventing water loss. Soil salinity is a matter of grave concern in various parts of the world, and silicon is a suitable candidate to mitigate salinity-induced stress of important plants in affected areas. The present study investigates the protective capability of exogenously applied silicon in ameliorating NaCl-induced toxicity in two rice (Oryza sativa L.) cultivars, the salt-sensitive MTU 1010, and salt-tolerant Nonabokra. Rice seedlings were treated with three doses of NaCl (25, 50, and 100 mM), initially alone and subsequently in combination with 2 mM sodium silicate (Na2SiO3, 9H2O). After 21 days, these plants were examined to determine levels of reduced glutathione, ascorbic acid, cysteine, and activities of different enzymes involved in the ascorbate-glutathione cycle, viz., glutathione reductase (GR), ascorbate peroxidase (APX), glutathione peroxidase (GPx), and glutathione S-transferase (GST). Though ROS levels increased in both the cultivars with increasing NaCl concentrations, cv. MTU 1010 accumulated comparatively higher amounts. A differential response of NaCl-induced toxicity on the two cultivars was observed with respect to the various enzymatic and non-enzymatic antioxidants. APX and GST activities, as well as, cysteine contents, increased concomitantly with salt concentrations, whereas GR activity declined at increasing salt concentrations, in both cultivars. Activity of GPx increased in cv. Nonabokra but declined in cv. MTU 1010, under similar NaCl concentrations. Reduced glutathione (GSH) contents decreased in both cultivars, whereas ascorbate contents declined in only the sensitive cultivar. Application of silicon, along with NaCl, in the test seedlings of both the cultivars, reduced ROS accumulation and boosted antioxidant defense mechanism, through enhancing ascorbate and GSH levels, and activities of ascorbate-glutathione cycle enzymes as well. However, amelioration of salt-induced damages in the sensitive cv. MTU 1010 was more pronounced upon silicon administration, than the tolerant cv. Nonabokra. Thus, cv. MTU 1010 was found to be more responsive to applied silicon. Hence, this study was instrumental in realizing a successful strategy in silicon-mediated amelioration of salinity stress in plants.

The “quasi-essential element” silicon (Si) is notconsidered indispensable for plant growth and its accumulation varies betweenspecies largely due to differential uptake phenomena. Siliconuptake and distribution is a complex process involving the participation ofthree transporters (Lsi1, Lsi2 and Lsi6) and is beneficial during recovery frommultiple stresses. This review focuses on the pivotal role of silicon incounteracting several biotic and abiotic stresses including nutrientimbalances, physical stresses together with uptake, transport of this metalloidin a wide variety of dicot and monocot species. The knowledge on the beneficialeffects of silicon and possible Si-induced mechanisms of minimizing stress hasbeen discussed. Accumulation of silicon beneath the cuticles fortifies the cellwall against pathogen attack. Si-induced reduction of heavy metal uptake, root-shoottranslocation, chelation, complexation, upregulation of antioxidative defenseresponses and regulation of gene expression are the mechanisms involved inalleviation of heavy metal toxicity in plants. Silicon further improves growthand physiological attributes under salt and drought stress. Effective use ofsilicon in agronomy can be an alternative to the prevalent practice oftraditional fertilizers for maintaining sustainable productivity. Therefore,soil nutrition with fertilizers containing plant-available silicon may beconsidered a cost-effective way to shield plant from various stresses, improveplant growth as well as yield and attain sustainable cultivation worldwide.

The activities of TCA cycle enzymes viz., pyruvate dehydrogenase, citrate synthase, isocitrate dehydrogenase, succinate dehydrogenase and malate dehydrogenase as well as levels of different organic acids viz., pyruvic acid, citric acid, succinic acid and malic acid were studied in two rice cultivars viz. cv. Nonabokra and cv. MTU 1010 differing in salt tolerance grown under 25, 50 and 100 mM NaCl salinity levels. A contrasting response to salt stress on enzyme activities of TCA cycle and accumulation of organic acid was observed between two cultivars during twenty-one days period of study. Salinity caused enhanced organic acid production and increase in all five enzyme activities in cv. Nonabokra whereas in cv. MTU 1010 decrease in both organic acid production and enzymes activities were noted. Joint application of exogenous silicon along with NaCl, altered the organic acids levels and activities of enzymes in both cultivars of rice seedlings conferring tolerance against salt induced stress. Rice cv. MTU 1010 showed better response to exogenous silicon on parameters tested compared to cv. Nonabokra.

Selenium is an essential and also toxic trace element for organisms including plants. We studied the role of selenium (Na2SeO4) on growth and carbohydrate metabolism and its interaction with sulphate (Na2SO4) in rice (Oryza sativa L. cv. Satabdi) seedlings. Low concentration of selenium (2µM) showed stimulatory effect on growth as opposed to its higher concentration (50µM). Selenium was found to accumulate in a dose dependent linear pattern in the plant tissues. Exposure to selenate increased both reducing and non reducing sugar contents in the rice seedlings accompanied with an increase in the activities of sugar metabolizing enzymes like Sucrose Synthase (EC 2.4.1.13) and Sucrose Phosphate Synthase (EC 2.4.1.14). An increase in Starch Phosphorylase (EC 2.4.1.1) activity corresponded with the reduction in starch contents in the rice seedlings. Since Selenium is chemically analogous to sulphate, simultaneous application of sodium sulphate (10mM) and selenate (Na2SeO4) was found to ameliorate partially or totally all the tested parameters under selenate treatment alone resulting in alteration of growth and development of the test seedlings.

The failure of BOF hood tube is a common industrial problem that has received little attention in literature. The major mode of failure as observed by most of the industries is thermal fatigue failure. Earlier people have studied the thermal stress profile in hood system considering constant water temperature. However, in reality there are fluctuations in water temperature due to cyclic thermal load caused by BOF gas. Present study reveals that the water temperature fluctuation is having significant impact in causing thermal fatigue failure. The change in water velocity and tube thickness has negligible effect in thermal fatigue failure compared to that observed for water temperature fluctuation. However, tube material of construction is also having significant impact on its failure.

Dense magnesium oxide (MgO) doped multiwalled carbon nanotube (MWCNT) reinforced alumina (Al2O3) nanocomposites were fabricated using spark plasma sintering (SPS). Sintered nanocomposites possessed refined microstructure due to the presence of uniformly dispersed CNTs and ability of MgO to increase densification rate before onset of abnormal grain growth. Williamson-Hall analyses of XRD patterns indicated that matrix crystallite size (L-C) and lattice micro-strain (epsilon(C)) of the nanocomposites decreased by similar to 40% and >30%, respectively, than those of pure Al2O3 (L-C approximate to 75 nm, epsilon(C) = 1.54 x 10(-3)). Present investigation also depicted the suitability of CNT addition in Al2O3 towards achieving higher density of nanocomposites using low temperature (1300 degrees C) SPS. Addition of CNT (especially, at >= 0.6 vol.%) in highly electrically insulating matrix established an electrical percolating network that helped in local heating of matrix particles during SPS and led to higher densification. The highest changes in indentation fracture toughness at 1 kgf and wear rate at 20N normal load were obtained at only 0.6 vol.% MWCNT loading which were >22% higher and 35% lower, respectively, compared to pure Al2O3. (C) 2015 Elsevier B.V. All rights reserved.

The effect of NaCl with or without silicon on the growth and metabolism in rice seedlings cv. MTU1010 was studied. In these seedlings, the oxidative stress has been observed with NaCl treatments and the levels of proline, H2O2 and malondialdehyde contents were increased whereas catalase activity was decreased. NaCl exposure at 25 mM, 50 mM and 100 mM concentrations in the test seedlings resulted in an increase in both reducing and non-reducing sugar content. There was a decrease in starch contents and the activity of starch phosphorylase was increased. NaCl stress also affected the activities of different carbohydrate metabolizing enzymes. The activities of sucrose synthase and sucrose phosphate synthase were increased, while the activity of acid invertase was decreased. Joint application of silicon with NaCl showed significant alterations on all parameters tested under the purview of NaCl treatment alone leading to better growth and metabolism in rice seedlings. Thus the use of silicon enriched fertilizers may help to grow healthy rice plants in NaCl rich soil.

Multiwalled carbon nanotube (MWCNT)/silicon carbide (SiC) composites were fabricated by spark plasma sintering at 2000 °C under 50 MPa for 10 min in Argon. Physical properties and Williamson–Hall analyses of X-ray diffraction patterns indicated strong influence of CNT on densification, crystallite size, and lattice micro-strain of pure SiC. Structural retention of CNTs, CNT/SiC interactions, and formation of 3–4 nm thick interface in sintered composites were confirmed through electron microscopy. Meyer’s exponent (1.84–1.89) of hardness data indicated almost similar indentation size effect in the studied specimens. Modified proportional specimen resistance model revealed formation of compressive surface residual stress and enhanced elastic response in CNT/SiC composites compared to pure SiC. R-curve sensitivity of present composites (toughening exponent, n ranged from 0.231 to 0.247) was found to be much improved than that obtained for pure SiC (n = 0.155). The 0.3 wt% MWCNT/SiC composite offered the highest toughness (3.93–5.56 MPa-m0.5) within the investigated loading range which was 17–31 % higher than those of monolithic SiC. Present composites also offered much better wear resistance up to 20 N. Wear rate of 0.1 wt% CNT/SiC composite was found to be more than 47 % lower than that obtained for pure SiC. At the highest CNT loading i.e., 1.2 wt%, composite also showed 10–12 % reduction in friction coefficient (μ) over monolithic SiC (μ = 0.53–0.58) due to the self-lubrication ability of CNT.

In this work, Pure boron carbide (B4C) was consolidated using spark plasma sintering (SPS) at 2050°C with a dwell of 10min under 50MPa uniaxial pressure in Argon atmosphere. The sintered specimen was >99% dense and offered characteristic Vickers hardness and fracture toughness of 31.4GPa and 4.21MPa-m0.5, respectively, at 4.9N indentation load. The specimen showed satisfactory wire electrical discharge machining (WEDM) performance because of its good electrical conductivity. The design of experiment (DOE) was arranged by L32 orthogonal array (OA) between the machining input parameters namely pulse on-time, pulse off-time, pulse peak current, dielectric fluid pressure and servo feed rate and the output responses like machining speed and surface roughness (Ra). Regression models were employed to establish the numerical correlation between the machining parameters and output responses. Experimental observations were utilized to formulate the first-order regression models to predict responses of WEDM. The optimized input parameters were 27 μs pulse on time, 48 μs pulse off time, 180A pulse peak current, 7kg/cm2 water pressure and 2200mm/min servo feed rate for the WEDM performance to produce an optimum machining speed and Ra.