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Gut malrotation or non-rotation is mainly a problem of the pediatric age group, however, adult and late adult presentation are not rare. Various cases of gastrointestinal malignancies associated with gut malrotation have been reported in the past. The true association between these two entities is unknown. This is one such rare case of carcinoma stomach associated with intestinal non-rotation in an adult patient. The patient was asymptomatic of non-rotation but developed symptoms of carcinoma of the stomach and non-rotation were diagnosed incidentally. The patient was treated for carcinoma and prophylactic appendectomy was done and non-rotation was left untouched.

Machining performance of monolithic alumina (Al2O3) tool inserts for metal cutting through carbon nanotube (CNT) incorporation was studied in this work. 0.3 vol% multiwalled CNT(MWCNT)-Al2O3 nanocomposite was prepared by hot-pressing at 1550°C with a dwell of 1 h under 2.5 MPa uniaxial pressure in static argon atmosphere. The hot-pressed nanocomposite achieved >99.5% of its theoretical density. The specimen also offered improved fracture toughness, KIC (~23% higher), flexural strength, σFS (~10% higher), hardness, HV1 (~7.5% higher) and thermal conductivity, κ (~30% higher) compared to those of pure Al2O3 (KIC = 5.23 MPa-m0.5, σFS = 341.01 MPa, HV1 = 18.80 GPa, κ = 23.69 W/mK). Inserts developed with this nanocomposite having 0.8 and 1 mm nose radii demonstrated successful machining during turning of AISI 4340 steel rod (hardness = 38 HRC) in dry environment under different cutting conditions and showed promising applicability in machining industry.

The thermodynamics of the oxidation of three-high temperature $$\hbox {ZrB}_{2}$$ -based ceramics ( $$\hbox {ZrB}_{2}$$ – $$\hbox {TiB}_{2}$$ , $$\hbox {ZrB}_{2}$$ –SiC and $$\hbox {ZrB}_{2}$$ – $$\hbox {B}_{4}\hbox {C}$$ ) has been studied in order to find the stability domain of zirconium diboride, in terms of temperature, partial pressure of oxygen and composition, in which it is protected against oxidation. In the case of the $$\hbox {ZrB}_{2}$$ – $$\hbox {TiB}_{2}$$ binary system, a plot of log $$p_{\mathrm{O}_{2}}$$ vs. 1/T in the temperature range of 500–2000 K and another plot of $$p_{\mathrm{O}_{2}}$$ ( $$\times 10^{14}$$ ) vs. $$x_{\mathrm{TiB}_{2}}$$ for $$T = 2000\hbox { K}$$ are made taking into account the two-extreme possibilities of no solubility and 100% solid solubility between $$\hbox {ZrB}_{2}$$ and $$\hbox {TiB}_{2}$$ , respectively. A plot of log $$p_{\mathrm{CO}}$$ vs. log $$p_{\mathrm{O}_{2}}$$ is made for 1773 K for the systems $$\hbox {ZrB}_{2}$$ –SiC and $$\hbox {ZrB}_{2}$$ – $$\hbox {B}_{4}\hbox {C}$$ . It was found that the $$\hbox {ZrB}_{2}$$ – $$\hbox {TiB}_{2}$$ ceramics does not have sufficient oxidation resistance in the temperature range of 500–2000 K. $$\hbox {ZrB}_{2}$$ of $$\hbox {ZrB}_{2}$$ –SiC ceramics can be protected under 1 atmosphere oxygen or in air if the liquid borosilicate (with the chosen composition, 70% $$\hbox {B}_{2}\hbox {O}_{3}$$ –30% $$\hbox {SiO}_{2}$$ ), which is an intermediate product, provides a kinetic barrier to the continuation of oxidation by forming an impervious layer on the exposed surfaces. In contrast, the $$\hbox {ZrB}_{2}$$ – $$\hbox {B}_{4}\hbox {C}$$ ceramics does not produce the borosilicate upon oxidation. In view of the volatility of pure liquid $$\hbox {B}_{2}\hbox {O}_{3}$$ , it is recommended that the $$\hbox {ZrB}_{2}$$ – $$\hbox {B}_{4}\hbox {C}$$ ceramics can be used at a lower temperature, perhaps below 1373 K, when the vapour pressure of $$\hbox {B}_{2}\hbox {O}_{3}$$ is significantly small.

This chapter presents the basic material properties of pressureless sintering (PLS) processed multi-walled carbon nanotube/Al2O3 to elucidate the adequacy of PLS technique towards fabricating such nanocomposites having improved performance over pure Al2O3. Considering the structural integrity aspect of carbon nanotube (CNT) in sintered nanocomposites, morphological stability of present nanotubes during high temperature exposure in inert atmosphere was studied prior to the nanocomposite fabrication. The CNT clusters in high nanotube containing batches facilitated localized densification of the matrix phase that formed a segregated microstructure and eventually, produced the macroscopic cracks. Presence of clustered CNTs, porous microstructure and inadequate interface in this high CNT loaded nanocomposite resulted in much higher defect population. The chapter describes the sequential changes observed at the interface region of the studied nanocomposites as a function of sintering temperature. The observed discrepancy in the extent of toughness improvement in CNT/Al2O3 nanocomposites is quite common and yet ambiguous.

In this work, Pure boron carbide (B 4 C) was consolidated using spark plasma sintering (SPS) at 2050 °C with a dwell of 10 min under 50 MPa uniaxial pressure in Argon atmosphere. The sintered specimen was >99% dense and offered characteristic Vickers hardness and fracture toughness of 31.4 GPa and 4.21 MPa-m 0.5 , respectively, at 4.9 N 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 ( R a ). 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, 180 A pulse peak current, 7 kg/cm 2 water pressure and 2200 mm/min servo feed rate for the WEDM performance to produce an optimum machining speed and R a .

For utilizing the outstanding energy absorbing capacity of highly elastic carbon nanotube (CNT), bulk multiwalled CNT (MWCNT) structure containing 15 wt% alumina (Al2O3) was fabricated using spark plasma sintering at 1600°C for 10 min under 50 MPa. The compacted mass was ~85% dense having morphologically stable MWCNTs. Microindentation studies up to 9.81 N indicated outstanding elastic recovery of the bulk structure leaving only a diffused indentation mark at indenter-specimen interaction zone. Quantitative estimation of elastic response behavior of the fabricated structure using instrumented nanoindentation in 10–300 mN load range indicated promising applicability of Al2O3/MWCNT compact structure as energy absorbing material.

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.

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 (LC) and lattice micro-strain (eC) of the nanocomposites decreased by ∼40% and >30%, respectively, than those of pure Al2O3 (LC ≈ 75 nm, eC = 1.54 × 10−3). Present investigation also depicted the suitability of CNT addition in Al2O3 towards achieving higher density of nanocomposites using low temperature (1300 °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.

Graphite particle (GP)-reinforced silicon nitride (Si3N4) composites were fabricated using pressureless sintering (PLS) and spark plasma sintering (SPS) in the presence of Y2O3-AlN-SiO2 ternary system. Different densification behaviors of the specimens fabricated by PLS and SPS were observed. While increasing GP content drastically reduced matrix densification during PLS at 2023 K (1750 °C) with 2 hours dwell, SPS at 1923 K (1650 °C) for only 10 minute under 50 MPa pressure resulted in much dense composites even up to 3.5 wt pct GP loading. Mechanical and tribological characterizations revealed that SPS-ed composites can offer improved performance compared to pure Si3N4. SPS-ed 1.5 wt pct GP/Si3N4 composite offered the highest resistance to wear up to 20 N normal load. Wear rate (W R) of that composite reduced by ~24 pct than that obtained for pure Si3N4 (W R ≈ 1.14 × 10−3 mm3/N m). Furthermore, W R of SPS-ed 2.5 wt pct GP/Si3N4 composite at F N = 10 to 20 N was found to be only ~1/8th of W R values of PLS-ed 2.5 wt pct GP/Si3N4 composite (10N W R ≈ 6.61 × 10−3 mm3/Nm; 20N W R ≈ 9.45 × 10−3 mm3/Nm). Present study indicated promising opportunity of SPS for fabricating improved Si3N4 composites through GP addition. The reinforcing particles not only rendered its self-lubrication effect to SPS consolidated composites but also significantly promoted the rate of matrix densification during SPS cycle by the virtue of its high thermal and electrical conducting nature.

ZrB2-SiCp (w/w 80:20) composites were spark plasma sintered at 1900, 2000 and 2100 degrees C with t(on) = 50 ms and t(off) = 5 ms conditions under 50 MPa pressure for 15 min. SiC was obtained by in situ pyrolysis of polycarbosilane during sintering. The FTIR spectra of semi-pyrolysed ZrB2-SiCp powder showed that pre-ceramic PCS polymeric bands such as Si-CH2-Si, Si-CH3 and Si-H weakened and few characteristic bands like Si-C, Si-O and C = C peaks appeared strong in the spectra. In ZrB2-SiCP composition, uniform distribution of ZrB2 and secondary SiC phases were found in the sintered sample. The interfaces between hexagonal ZrB2 and needle shaped SiC were found in high resolution bright field TEM images. The Vickers' micro-hardness, fracture toughness (measured by DCM) of ZrB2-SiCp composite sintered at 2000 degrees C achieved up to 16.22 GPa and 3.69 MPa root m, respectively. The critical energy release rate (G(IC)) value was 27.46 J.m(-2) implying that the composite resists fracture during indentation. Wear resistance coefficient and wear rate values of all the composites were found to be very low. Thermal conductivity values of all the composites varied from 78.09 to 57.20 W/m.K in 100 degrees C to 1000 degrees C range. (C) 2015 Elsevier Ltd. All rights reserved.

Multiwalled carbon nanotube (MWCNT)/alumina (Al2O3) nanocomposites were fabricated using two varieties of CNT to access the effect of morphological variation of the filler on fracture resistance (K R)/toughness (K IC) of studied specimens. Special attention was also given to compare K R and K IC values for tracing out the primary selection criterion of appropriate indentation fracture (IF) equation used in relatively faster and simpler ‘direct crack measurement’ (DCM) technique to evaluate K R values close to stringent ‘single edge notched beam’ (SENB) derived K IC data. While K IC was calculated using the unique expression suitable for specimens tested under four-point flexure, K R values were evaluated using a series of IF equations suitable for Palmqvist and/or median crack systems. As far as change in K R and/or K IC of nanocomposites was concerned, it was noticed that for longer/thicker CNTs having relatively higher internal bamboo structures, much lower amount (0.15 vol pct) was adequate to achieve the highest improvement in K R (~87 pct) or K IC (~50 pct) over pure Al2O3 (Laugier K R ≈ 3.83 MPa-m0.5; K IC ≈ 3.48 MPa-m0.5) than that required for smaller/thinner CNTs (≥0.3 vol pct). On contrary, resistance to fracture up to 1.2 vol pct CNT loading was much enhanced in specimens fabricated with smaller/thinner CNTs over those fabricated using longer/thicker CNTs. Comparatively better morphology, adequate CNT dispersion, and higher population of bridging elements in specimens containing smaller/thinner CNTs were the key factors behind such toughness retention.

Magnesia doped multiwalled carbon nanotube (CNT)/α-alumina nanocomposites have been fabricated by spark plasma sintering at 1500°C under 50 MPa in argon. Owing to combined grain refining effect of nanotube and magnesia, nanocomposites possessed smaller matrix grains and extensively lower matrix crystallites than pure alumina. Thermal expansion mismatch between matrix and filler rendered up to four times higher compressive lattice microstrain to the nanocomposites over pure alumina. Despite very low CNT loading (e.g. 0·13 wt-%), nanocomposites offered considerably higher hardness (as high as 24·42 GPa), negligible indentation size effect (Meyer exponent = 1·906 − 1·941) and enhanced elastic response over pure alumina. Up to 0·27 wt-% nanotube loading, much higher wear resistance was observed for the nanocomposites over pure alumina. The presence of uniformly dispersed and structurally intact nanotubes coupled with lower matrix grains and crystallites having compressive lattice strain were the key factors b...

Liquid Polycarbosilane derived β-SiC and α-SiC coating was deposited at three differently moderate high temperatures by CVD method on Silicon wafers. The nano-mechanical properties such as hardness, reduced Young's modulus, elastic recovery and plasticity index of the coatings were evaluated and compared at different deposition temperature. It was observed that with the increase in deposition temperature the nano-mechanical property of the coating enhances, the reason being the increase in crystallinity along with good adherence at higher temperature. Moreover the tribological properties of the coated samples show similar trends with increase in deposition temperature although it were found to be much better for the β-SiC than that of the α-SiC coated samples. All the coated samples shows brittle mode of failure during tribological testing. It was found that the 900 °C deposited film has better nano-mechanical as well as good tribological properties compared to other temperature of deposition due to better crystallinity and adherence. Thus the enhanced mechanical and tribological properties of this coating can be used as protective films on silicon for application in micrometers and other micro devices.

The influence of direct current pulse on–off patterns on spark plasma sintering of ZrB2 on densification, mechanical and tribological properties has been investigated systematically. The experimental data showed that the maximum relative density (98.65%) is achieved at 50 ms pulse on (ton) and 5 ms pulse off (toff) time conditions. The maximal Vickers hardness, fracture toughness (DCM) at 1 kgf load, wear volume and wear rate at 10 N load of the ZrB2 sample (ton = 50 ms and toff = 5 ms pulse conditions) were 16.64 GPa, 4.69 MPa√m, 4.05 × 104 μm3 and 1.01 × 10− 3 mm3/N·m, respectively. The electric current delivered during SPS processes in different ‘on–off’ pulse patterns plays a vital role in consolidation and desired structural properties.

SiC-TiB2 (10 wt. %) and SiC-TiB2 (10 wt. %)-TaC (5 wt. %) composites are consolidated using spark plasma sintering (SPS) technique at different sintering temperatures (2000 degrees C and 2100 degrees C) for 15 min soaking time under 35 MPa pressure. The effects of sintering temperature on densification and mechanical properties of composites have been investigated in detail. SiC-TiB2 and SiC-TiB2-TaC composites sintered at 2100 degrees C showed high Vickers hardness value, i.e., 27.20 +/- 1.23 GPa and 26.40 +/- 0.80 GPa, respectively, under 1 kgf (9.81 N) load. Poor fracture toughness {2.28 MPa(m)(1/2) at 1 kgf (9.81 N) load} of monolithic silicon carbide (SiC) sintered at 2100 degrees C is improved with addition of titanium diboride (TiB2) and. tantalum carbide (TaC) as secondary phases. Scratch resistance of SiC-TiB2 and SiC-TiB2-TaC composites show coefficient of friction value below 0.40 and 0.50 under 5N and 10N loads, respectively. SiC-TiB2 and SiC-TiB2-TaC composites show constant thermal conductivity response above 810 degrees C and 603 degrees C in the. range, of 48.70-47.15 W/m K and 60.35-60.41 W/m K, respectively.

ZrB2-SiC composites were hot pressed at 2473 K (2200 °C) with graded amounts (5 to 20 wt pct) of SiC and the effect of the SiC addition on mechanical properties like hardness, fracture toughness, scratch and wear resistances, and thermal conductivity were studied. Addition of submicron-sized SiC particles in ZrB2 matrices enhanced mechanical properties like hardness (15.6 to 19.1 GPa at 1 kgf), fracture toughness (2 to 3.6 MPa(m)1/2) by second phase dispersion toughening mechanism, and also improved scratch and wear resistances. Thermal conductivity of ZrB2-SiC (5 wt pct) composite was higher [121 to 93 W/m K from 373 K to 1273 K (100 °C to 1000 °C)] and decreased slowly upto 1273 K (1000 °C) in comparison to monolithic ZrB2 providing better resistance to thermal fluctuation of the composite and improved service life in UHTC applications. At higher loading of SiC (15 wt pct and above), increased thermal barrier at the grain boundaries probably reduced the thermal conductivity of the composite.

ZrB2-TiB2-based ceramics with varying amount of TiB2 (up to 30 wt%) were hot pressed at 2200 °C in Ar atmosphere, and the effect of the TiB2 addition on mechanical properties like hardness, fracture toughness, scratch resistance, wear resistance and thermal conductivity of the system was compared to monolithic ZrB2 ceramic. It was found from X-ray diffraction that TiB2 completely entered into the structure and formed solid solution with ZrB2. Addition of TiB2 in ZrB2 system improves the mechanical and wear resistance properties. ZrB2-TiB2 (30 wt%) ceramic, for example, showed highest hardness of 22.34 GPa, fracture toughness 3.01 MPa(m)1/2 and lowest coefficient of friction (0.398 at 10 N load). The addition of TiB2 in ZrB2 system showed lower thermal conductivity than monolithic ZrB2 by increasing grain boundary thermal resistance.

The effect of addition of submicrometer-sized B4C (5,10 and 15 wt%) on microstructure, phase composition, hardness, fracture toughness, scratch resistance, wear resistance, and thermal behavior of hot-pressed ZrB2-B4C composites is reported. ZrB2-B4C (10 wt%) composite has VH1 of 20.81 GPa and fracture toughness of 3.93 at 1 kgf, scratch resistance coefficient of 0.40, wear resistance coefficient of 0.01, and ware rate of 0.49 × 10−3 mm3/Nm at 10N. Crack deflection by homogeneously dispersed submicrometer-sized B4C in ZrB2 matrix can improve the mechanical and tribological properties. Thermal conductivity of ZrB2-B4C composites varied from 70.13 to 45.30 W/m K between 100°C and 1000°C which is encouraging for making ultra-high temperature ceramics (UHTC) component.

ZrB2–SiC composites were prepared by hot pressing with different sources of SiC to study the effect of SiC with different morphology on densification, microstructure, phase composition and mechanical properties like hardness, fracture toughness and tribological properties (namely, scratch resistance, wear parameters) and thermal behaviour of the composites. Three different ZrB2–SiC composites, i.e. ZrB2–SiCP (polycarbosilane derived SiC), ZrB2–SiCC (SiC from CUMI, India) and ZrB2–SiCH (SiC from H. C. Starck, Germany), were studied. It is found that ZrB2–SiCC composite shows highest hardness (19·13 GPa) and fracture toughness (5·30 MPa m1/2 at 1 kgf load) in comparison with other composites. Interconnected network, better contiguity between grains of ZrB2–SiC composites and impurity content in starting powders can play significant roles for achieving high mechanical, tribological and thermal properties of the composites. Coefficient of friction and wear parameters of all ZrB2–SiC composites are ver...

Liquid polycarbosilane (LPCS) derived hard coatings of silicon carbide (SiC) were deposited on Inconel alloy at three different moderately high temperatures by chemical vapour deposition. The deposited films were characterized by X-ray diffractometry and Field emission scanning electron microscopy. Liquid PCS yielded a mixture of α-SiC and β-SiC during decomposition having uniform round-shaped particles of dimension around 200–300 nm without extensive cracking and few discrete shaped particles were also found to form at higher temperature (i.e. 1100 °C and 1200 °C) deposited films. The coated samples showed substantial increment in hardness and fracture toughness as compared to the uncoated sample. The fracture toughness (K IC ) values of the deposited films were in the range of 6.7–10.7 MPa(m) 1/2 . The tribological properties and hardness of the films were also found to vary with deposition temperature. The scratch tracks of the films revealed that brittle failures occurred in all SiC coated substrates.

Multiwalled carbon nanotube (MWCNT)/alumina (Al 2 O 3 ) nanocomposites were prepared by simple wet mixing of MWCNT and Al 2 O 3 powder followed by pressureless sintering in static Argon. X-ray diffraction (XRD) line broadening analyses using Williamson–Hall ( W – H ) technique revealed a polynomial dependence of crystallite size ( D V ) on sintering temperature ( T sin ) and volume percent CNT added ( V CNT ) as D V ≈ [ 0.9 ( T s i n ) − 770 ] + [ − 1 . 1 ( T s i n ) + 1489 ] ( V C N T ) + [ 0 . 4 ( T s i n ) − 547 ] ( V C N T ) 2 . While the highest increase (~14%) in Vickers hardness ( HV ) over pure Al 2 O 3 was offered by 0.15 vol% MWCNT/Al 2 O 3 specimen, the highest fracture toughness ( K IC ~5 MPa m 0.5 ) and flexural strength ( σ FS ~260 MPa) were obtained for nanocomposite containing 0.3 vol% MWCNT which were ~26% and ~16% higher, respectively, than those of pure Al 2 O 3 . The 0.15 vol% MWCNT/Al 2 O 3 specimen also offered maximum increase (~22%) in thermal conductivity over unreinforced Al 2 O 3 (~39 W/m K). Electrical percolation in nanocomposites was observed between 0.6 and 1.2 vol% CNT loading.

Single wall carbon nanotubes (SWCNTs) were successfully entrapped in lead silicate glass by the melt quench technique. Variation of micro hardness with load for lead silicate glass and the composites (having different wt% of SWCNTs) show Reverse Indentation Size Effect (RISE). Meyer's law, the proportional specimen resistance (PSR) model and the modified PSR model have been analyzed for the load dependent hardness of the glass and the composites. Incremented elastic recovery in the composites than that of the glass was explained by the appealing cushioning performance of entangled SWCNT bundles. In contrast, higher plastic deformation beneath the indenter in the composites was established by evaluating the recovery resistance of the materials.

Interface of multiwalled carbon nanotube (MWCNT)/alumina (Al 2 O 3 ) nanocomposites have been studied using TEM. At low sintering temperature ( T sin =1500 °C), a 3–5 nm thick amorphous interface region was noticed. Nanocomposite sintered at 1700 °C possessed a well-defined graphene layer coating on matrix grains as the interface between CNT and Al 2 O 3 . A mechanism of such layered interface formation has been proposed. No traceable chemical reaction product was observed at the interface even after sintering at 1700 °C. It was noticed that while DC electrical conductivity ( σ DC ) of 1500 °C sintered 2.4 vol% MWCNT/Al 2 O 3 nanocomposite was only~0.02 S/m, it raised to ~21 S/m when sintering was done at 1700 °C. Such 10 3 times increase in σ DC of present nanocomposite at a constant CNT loading was not only resulted from the exceptionally high electron mobility of CNT but the well-crystallized graphene interface on insulating type Al 2 O 3 grains also significantly contributed in the overall increase of electrical performance of the nanocomposite, especially, when sintering was done at 1700 °C.

Enhanced electrical conductivity of SWCNT-Lead silicate glass composite was observed in the temperature range of 308 K–473 K. Current–Voltage characteristics of the composite was found to be ohmic in nature, wherein the electrical conductivity was observed to increase significantly with the increase in temperature. Optical properties of the composite through UV-VIS-NIR absorption and NIR fluorescence spectroscopy were ascertained wherein one can observe broad fluorescence between 861 and 1904 nm at room temperature. Micro structural analysis by HRTEM and FESEM shows that single walled carbon nanotubes were randomly distributed inside the glass matrix in the form of bundles. Finally the electrical and optical properties of the composite were explained by fluctuation induced tunneling model, exciton–exciton resonance and excitonic energy transfer.

Abrasive Water Jet Machining (AWJM) process has potential to cut a wide range of materials. Researchers did a number of experiments on cutting of different grades of steel, copper, aluminium, 87% alumina ceramics, Ti6Al4 V, different types of stone etc by AWJM. Though, applicability of AWJM on crystalline materials is established, yet no such work is found on amorphous materials. Borosilicate glass is one of the most regularly used amorphous engineering materials. Brittleness of this glass puts limitation on its machining by conventional machining processes. In this article, experiments are conducted on cutting of borosilicate glass by AWJM. Depth of cut is measured with different machine parameter settings – water pressure, abrasive flow rate, traverse speed and standoff distance. Model, thus developed, on depth of cut gives an idea of the influence of different parameters on cutting of amorphous borosilicate glass by AWJM. Optimum condition of control parameter setting is also searched through particle swarm optimization (PSO). In addition, scanning electron microscopic image reveals to some extent, the nature of cut surface and erosion behaviour of amorphous material qualitatively.

Different types of snake venom including LAAO venom found in different organism which possesses anticancer effect as well as other pharmacological activity. Now a days using medicine for cancer treatment that have a lots of adverse effect such as alopecia, bone marrow depression, vomiting etc., we are focusing on SV-LAAOs to search out the natural bioactive novel agents. King cobra venom LAAO has more stability than other SV-LAAOs which may be correct agent to developed anticancer medicine. These effects mainly produced due to hydrogen peroxide which is generated during catalytic reaction.

Silicon carbide coating on silicon (1 1 1) wafer was deposited by modified chemical vapor deposition (CVD) method using liquid polycarbosilane (LPCS) as precursor at three different moderately high temperatures in presence of Argon gas. Glancing angle X-ray diffractometer and Fourier Transform Infrared Spectroscopy reveals smooth β-SiC coating and its subsequent transformation into α-SiC on silicon substrate. In all the temperature the film was found to be uniform with a thickness ranging from 0.6–1.2 μm. The average particle size as can be seen from FESEM ranges from 7 to 385 nm approximately, the lowest range being (7–20 nm) which hitherto has not yet been reported using LPCS as precursor for SiC. Moreover the coated samples show substantial increment of hardness (∼18.8 GPa) and toughness (∼1.51 MPa m 1/2 ), both of which increases with increase in deposition temperature. The smooth and thin SiC coating on silicon formed in three different moderate temperatures compared to very high temperature for other CVD assisted coating along with enhanced hardness and toughness makes this a promising material in critically harsh environment required for microelectromechanical systems (MEMS) application.

Mechanical properties of pressureless sintered 0.15–1.2 vol.% multiwalled carbon nanotube reinforced alumina matrix nanocomposites have been analyzed using the 2-parameter Weibull statistics. Electron microscopy and phase analysis of nanocomposites sintered at 1700 °C for 2 h in Argon revealed existence of interpenetrating network of nanotubes in alumina, formation of thin interface resembling stoichiometric aluminum monoxycarbide and matrix grain refinement by nanotubes. Statistical analyses indicated that with increasing Vickers hardness testing load (4.9–19.6 N) and flexural strength measurement temperature (room temperature to 1100 °C), Weibull modulus of nanocomposites increased significantly suggesting improved consistency at higher load and temperature. The highest Weibull moduli were obtained for nanocomposites containing either 0.15 or 0.3 vol.% nanotube which were ∼40% and ∼15% higher than single phase alumina for hardness and strength, respectively, supporting the specimen size effect on reliability of present brittle ceramic matrix nanocomposites. Superior mechanical reliability of nanocomposites over pure alumina was primarily attributed to the presence of structurally intact nanotubes forming effective interface region to ensure proper load sharing, matrix grain refinement, and especially, at higher testing load and temperature, overall averaging effect of flaws to yield higher Weibull moduli.

Multiwalled carbon nanotube (MWCNT)/alumina (Al2O3) nanocomposites containing CNT from 0.15 vol.% to 2.4 vol.% have been successfully fabricated by simple wet mixing of as-received commercial precursors followed by pressureless sintering. Extent of densification of nanocomposites sintered at low temperature (e.g. 1500 °C) was

Multiwalled carbon nanotube (MWCNT)/alumina (Al 2 O 3 ) nanocomposites having different CNT contents have been fabricated by wet-mixing and pressureless sintering in Argon at 1700 °C. Depending on indentation load, the highest improvement of 15–34% in hardness was achieved in 0.3 vol.% MWCNT/Al 2 O 3 nanocomposite. Indentation size effect ( Mayer ' s exponent = 1.753) on hardness was the most prominent in 1.2 vol.% MWCNT/Al 2 O 3 nanocomposite due to presence of clustered CNTs, non-uniform interface and porous microstructure. ∼34% increase in fracture toughness was achieved in 0.3 vol.% MWCNT/Al 2 O 3 nanocomposite than pure Al 2 O 3 (∼3.84 MPa m 0.5 ). High MWCNT loaded nanocomposites had reduced R-curve sensitivity because of increased matrix grain refining effect and reduced matrix compressive residual stress. High temperature flexural strength results indicated that strength retention of nanocomposites up to 1100 °C in ambient was much better compared to pure Al 2 O 3 . To predict structure–property relationship in nanocomposites, detailed microstructural and fractographic studies were also performed.

A number of graphite–clay composites with varying percentages of graphite in the clay host have been prepared and their AC conductivities and dielectric behaviours have been studied in the frequenc...

Non-isothermal oxidation kinetics of single- and multi-walled carbon nanotubes (CNTs) have been studied using thermogravimetry up to 1273 K in ambient using multiple heating rates. One single heating rate based model-fitting technique and four multiple heating rates based model-free isoconversional methods were used for this purpose. Depending on nanotube structure and impurity content, average activation energy (Ea), pre-exponential factor (A), reaction order (n), and degradation mechanism changed considerably. For multi-walled CNTs, Ea and A evaluated using model-fitting technique were ranged from 142.31 to 178.19 kJ mol−1, respectively, and from 1.71 × 105 to 5.81 × 107 s−1, respectively, whereas, Ea for single-walled CNTs ranged from 83.84 to 148.68 kJ mol−1 and A from 2.55 × 102 to 1.18 × 107 s−1. Although, irrespective of CNT type, the model-fitting method resulted in a single kinetic triplet i.e., Ea, A, and reaction mechanism, model-free isoconversional methods suggested that thermal oxidation of these nanotubes could be either a simple single-step mechanism with almost constant activation energy throughout the reaction span or a complex process involving multiple mechanisms that offered varying Ea with extent of conversion. Criado method was employed to predict degradation mechanism(s) of these CNTs.

2D carbon fiber (C-fiber)-reinforced carbon/carbon (C/C) composites were prepared by vacuum infiltration with coal-tar pitch followed by carbonization and graphitization in inert atmosphere. Liquid silicon infiltration was done in controlled atmosphere at 1600 degrees C to convert the matrix carbon of the C/C composites into silicon carbide. The 2D C/C and carbon/carbon-silicon carbide (C/C-SiC) composites had density of similar to 1.65 and similar to 2.32 g/cm3, respectively with corresponding flexural strength of similar to 70 and similar to 169 MPa, respectively. The local mechanical properties like hardness, Young's modulus, contact pressure, relative stiffness, relative spring back, and indentation energies of the two composites under different loading conditions were measured at an ultra low load of 10 mN using a nanoindentation instrument with a Berkovich indenter. The scatter in the data was treated in terms of the two-parameter Weibull statistical analysis. The maximum characteristic Young's modulus (similar to 16 GPa) and hardness (1.20 GPa) was obtained for the C/C-SiC composites in parallel direction of fabric stacking. The elastic rebounce was also the maximum (0.77) for the C/C-SiC composites when loaded in parallel direction of fabric stacking. The extent of structural anisotropy was higher in the C/C-SiC composite than that of the C/C composite.

High temperature treatment in inert atmosphere proved to be an effective way to improve high temperature stability of MWNTs in ambient condition. TEM analysis of heat-treated MWNTs confirmed successful removal of impurities and formation of ordered graphene layers and internal bamboo structure. TG–DTG curves indicated that decomposition range and rate of as-received MWNTs were narrow and notably higher, respectively, than heat-treated MWNTs mainly due to presence of impurities like metal nanoparticles in the former. Non-isothermal kinetic analysis revealed that the rate determining mechanism for as-received MWNTs was random nucleation and growth of active species. However, for heat-treated MWNTs, rate controlling mechanism was chemical reaction. Higher activation energies (∼203 kJ mol−1 and 280 kJ mol−1) and reaction orders (3 and 4) of MWNTs heat-treated at 1200 °C and 1800 °C in inert, respectively, indicated delayed thermal decomposition than as-received MWNTs (Ea ≈ 178 kJ mol−1; n = 1) even in oxidative atmosphere.

Single walled carbon nanotube–borosilicate glass composite has been fabricated in a controlled atmosphere furnace by a melt-quench technique. Current–voltage characteristics were analyzed at room temperature and found to be non-ohmic in behavior. The temperature dependence of the current–voltage characteristics was ascertained and it was observed that the electrical conductivity of the composite increased substantially with temperature. Analysis by scanning and transmission electron microscopy clearly demonstrates that the carbon nanotubes are randomly distributed in the form of bundles throughout the glass. The charge conduction mechanism of the composite was found to be well explainable by the fluctuation induced tunneling (FIT) model.

In this research work, development of a multi-response optimization technique was performed, using Genetic Algorithm (GA) optimization technique in wire electrical discharge machining (WEDM) keeping in mind about the priorities of multiple users. Boron carbide has been selected as work piece for experiment. The effect of five process parameters such as pulse on time (Ton), pulse off time (Toff), peak current (IP), water pressure (WP), servo feed (SF), were investigated on the responses such as machining speed and surface roughness (Ra) in WEDM operation. Further, two responses were modeled empirically through regression analysis. The developed models can be used by the machinists to predict the machining as well as the surface characteristics over a wide range of machining input parameters. The analysis of variance (ANOVA) is also applied to investigate the effect of influential input parameters. Finally, the confirmation experiments were conducted with optimal set of machining parameters and minor deviations have been found.

Platinum-based chemotherapy is one of the most common therapies employed in oral cancer treat-ment. This is a prospective cohort study to analyse the pattern and incidence of adverse drug reac-tions to platinum based chemotherapeutic regimens in oral cancer patients. Pharmacovigilance studies are still unexplored in oral cancer patients in Bihar (India). Oral cancer patients who received platinum-based cancer chemotherapy were monitored for adverse drug reactions. The collected re-ports analysed for demographic, causality, preventability and severity of adverse drug reactions. Causality was assessed by the World Health Organization causality assessment scale. Preventability and severity of adverse drug reactions assessed by modified Schumock and Thornton scale, modified Hartwig and Siegel scale respectively. Incidence rate, relative risk and attributable risk were evaluat-ed among the regimens. Out of 120 patients, 108 (90%) patients were males. 105 patients (87.5%) developed a total of 247 adverse drug reactions. World Health Organization UMC causality scale showed 82% of adverse drug reactions were “certain”, 15% were “probable” and 3% were “possi-ble”. Modified Hartwig and Siegel severity scale showed 89% of adverse drug reactions were “mild” and 11% were “moderate” type. Schumock and Thornton preventability scale showed 93% of ad-verse drug reactions were “not preventable” and 20% were “probably preventable”. Paclitax-el+carboplatin regimen showed lowest values in terms of adverse drug reactions. Platinum-based chemotherapy was used in the treatment of oral cancer. From this study it is evident that paclitax-el+carboplatin regimen reported least incidence rate of adverse drug reactions among platinum regi-mens. Incidence rate was more reported in cisplatin regimen.

A thieno[2,3-b]thiophene core has been utilized as a \pi-donor component to design two series of push–pull thienothiophenes by introducing various acceptor groups either via olefinic or aza-spacers. The molecules show a UV–visible cut-off wavelength below the second harmonic generation (SHG) at $ \lambda /2$ of 532 nm, thereby conforming to the nonlinearity–transparency trade-off. Second order molecular nonlinearity, \beta measured by Hyper-Rayleigh scattering technique was found in the range of $9.58–47.66 X 10^{-30} esu$, while the Kurtz powder technique produced signals of the order of 0.43–1.02 U. Thermal decomposition temperatures measured by differential scanning calorimetry revealed decomposition temperatures \geq 275° C, indicating high thermal stability.

Cervical cancer is the second most common gynecological malignancy worldwide. According to HPV Information Centre, Spain (Aug'2014), in India approximately 1,22,844 women are diagnosed with the disease every year and of them 67,477 die due to the disease. CaCx is said to be mediated by HPV but recent data published reveal the role of Oxidative Stress in different Cancers. Arsenic is also one of the agents for causing Oxidative Stress. Arsenic has been linked with different types of cancer. Arsenic is considered responsible for generation of free radicals and eventually for apoptosis. Early diagnosis of CaCx is presently a matter of concern and clinical presentation in advanced stages become difficult for complete clinical response. For determination of oxidative stress, Malondialdehyde (MDA) was taken as an identifier and arsenic estimation was performed with the help of Atomic Absorption Spectrometer (AAS). RBC count and Haemoglobin levels were performed according to standard protocol. MDA was in direct proportion with arsenic concentration and inversely proportional to RBC and Haemoglobin in CaCx patients. Arsenic is one of the major causative agents for oxidative stress and hence may be a risk factor leading to cancer including CaCx.

Cytokine behavior of T-lymphocytes is not very clear when a patient is co-infected with Leishmania donovani and HIV. To achieve this we studied groups of patients comprising of VL infected, HIV infected and HIV-VL co-infected cases. As compared to lone infections by either of the infecting agent, the co-infection cases showed greatly diminished CD4 T-cell counts and slightly enhanced values of cytokines (IFNγ and IL4). The effect of 63 KDa antigenic fraction of L. donovani, previously reported by our group as having potential immunoprophylaxis effects, was also studied for its effect on T-cell cytokine pattern in the co-infection cases. It was interesting to find that this antigenic fraction showed an increase in the proportion of CD4 T-cells secreting IFNγ in both VL (alone) and HIV-VL co-infection groups.

Pure alumina and zirconia powders were sintered separately with increasing amount of TiC up to ∼ 65 vol.%, as a conducting second phase with an aim to prepare conducting structural ceramics which can be precisely machined by EDM technique. TiC did not help in sintering the parent phase but it decreased the d.c. resistivity of the composite to 1 ohm.cm at ∼ 30 vol.% loading. The conductivity is explained by the effective media and percolation theories.

The efficacy of aqueous and freeze dried (FD) antigen was evaluated by direct agglutination test (DAT) for sero-diagnosis of visceral leishmaniasis. A total of 16 samples collected from 5 confirmed Kala-azar (KA) cases, 6 cases 2 each of filariasis, malaria, leprosy and 5 non-endemic healthy subjects were used in determination of cut off titre of both the antigens in DAT. A 1:800 for aqueous and 1:400 dilution for FD DAT antigen was found as cutoff values for differential diagnosis of KA cases from control subjects. Both antigens revealed 100% correlation in terms of sensitivity and specificity in diagnosis of KA cases and healthy subjects at these titres. Using both antigens and the cut off titres, sera from 26 individuals collected from different categories of leishmaniasis viz. Kala-azar pre-treatment 10, Kala-azar post-treatment 10, HIV-KA co-infection 1 and PKDL 5 were evaluated by DAT. Both the antigens showed equal sensitivity and specificity in diagnosis of different categories of leishmaniasis. The study concludes that though aqueous antigen showed equal sensitivity and specificity but FD antigen which is stable at 56oC do not require cold chain whereas aqueous antigen is unstable at room temperature and require proper cooling to retain its antigenic activity as studied in between day 1 and day 14, so the FD antigen should be used for routine diagnosis of KA cases particularly in field condition.

In Abrasive Water Jet Machining (AWJM), abrasive particles suspended in high pressure water are impinged on work surface for removal of excess materials. A nozzle is fitted in front of workpiece to provide high velocity jet. In this work, appropriate machining condition is tried to evaluate to yield minimum surface roughness by employing Response Surface Methodology (RSM) while machining low carbon steel. Radius of curvature is also observed during abrasive water jet machining. A statistical model is generated for predicting surface roughness. It is observed that at low feed rate condition, better surface is obtained expectedly.

MoSi2-RBSC composite samples were prepared by infiltration of Si-2 at.% Mo melt into a preform of commercial SiC and petroleum coke powder. The infiltrated sample had a density > 92% of the theoretical density (TD) and microstructurally contained SiC, MoSi2, residual Si and unreacted C. The material was tested for indentation fracture toughness at room temperature with a Vicker’s indenter andK IC was found to be 4.42 MPa√m which is around 39% higher than the conventional RBSC material. Enhancement in indentation fracture toughness is explained in terms of bowing of propagating cracks through MoSi2/SiC interface which is under high thermal stress arising from the thermal expansion mismatch between MoSi2 and SiC.

For reaction sintered SiC (RSSC) prepared at 1600°C by conventional melt infiltration technique, experimentation with two different particle sizes of initial SiC, viz., 0.2 and 23.65 μm, showed that the large SiC particles remained unaltered and the sizes of the fine-grained SiC increased several times yielding well-developed faceted crystals in the final material. To study the process further, compacts of SiC powder of particle sizes varying between 0.20 and 8.99 μm were reacted with pure Si at 1600°C and the resulting SiC–Si boundaries were studied by optical microscopy. A distinct boundary layer with no penetration of Si in the compact of SiC of 0.2 μm was observed and the width of the SiC–Si boundary was found to be increasing linearly with time. Detailed SEM examination establishes the growth of the SiC upto around 4 μm from 0.2 μm starting powder. No such growth was observed in the case of starting SiC powder coarser than 0.2 μm. The growth of SiC is explained in terms of solution-reprecipitation mechanism.

A time-temperature schedule for formation of silicon-nitride by direct nitridation of silicon compact was optimized by kinetic study of the reaction, 3Si + 2N2 = Si3N4 at four different temperatures (1250°C, 1300°C, 1350°C and 1400°C). From kinetic study, three different temperature schedules were selected each of duration 20 h in the temperature range 1250°-1450°C, for complete nitridation. Theoretically full nitridation (100% i.e. 66.7% weight gain) was not achieved in the product having no unreacted silicon in the matrix, because impurities in Si powder and loss of material during nitridation would result in 5–10% reduction of weight gain.

Investigations were carried out to find out the role of higher and lower ambient temperatures together with short and long photoperiods on ovarian growth and secretion of steroids (estradiol-17 beta and progesterone) in the adult female soft-shelled turtle Lissemys punctata punctata during the preparatory, recrudescent, and quiescent phases of its seasonal reproductive cycle. In each phase, females were treated with 3 degrees C higher and 3 degrees C lower than the mean highest and lowest ambient temperatures in association with short and long photoperiods for short-term (4 week) and long-term (8 weeks or more) durations. Short-term high-temperature treatment significantly stimulated ovarian growth and secretion of estradiol-17 beta during the preparatory phase. Eight-week treatment failed to exercise further stimulation over 4-week treatment, whereas 10-week treatment caused regressive changes of ovary (atresia of follicles). Both short- and long-term high-temperature treatments caused degeneration of ovarian follicles during the recrudescent phase. Low-temperature treatment slowed down ovarian growth and secretion in both the preparatory and recrudescent phases. In the quiescent phase, low- as well as high-temperature treatments exercised little influence over the refractory ovarian growth and secretion. Photoperiod appeared to have no effect on female reproduction in any phase. Thus, high temperature is suggested to have a triggering role on ovarian growth and secretion of estrogen at the early preparatory phase, but once the ovarian function sets in, high temperature seems to have a regressive rather than stimulatory effect on ovarian growth and function.

Due to the demand of the manufacturing industry for high production-rate machining, ceramic tool material plays an important role. In this work, alumina (Al 2 O 3 ) matrix composite reinforced with 0.3 vol.% multiwalled carbon nanotubes (MWCNTs) was prepared by hot-press sintering at a temperature of 1550°C under uniaxial load of 2.5 MPa. This developed nanocomposite having increased hardness, fracture toughness and flexural strength compared to monolithic Al 2 O 3 was then used as a cutting tool insert with a nose radius of 1 mm for machining AISI 1060 steel rod under different machining conditions. Cutting force was measured and chip forms were observed at different levels of machining parameters to evaluate the machining performance of the tool insert. Results obtained from turning experiments show promising applicability of the developed 0.3 vol.% MWCNT/Al 2 O 3 cutting tool insert.

Extraosseous Ewing’s sarcoma/primitive neuroectodermal tumor (EES/PNET) of the kidney is an uncommon entity and usually arises from the retroperitoneum and paraspinal region. We report a case of renal EES/PNET and discuss its clinical features, histological findings and management.