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XH 67 is a nickel-based superalloy, which is used in critical parts of modern aerospace engines. In the present study, XH 67 specimens in five different heat treatment conditions selected based on the processing and application have been investigated for their microstructures, morphology, and composition of the matrix and second-phase particles. Optical microscopic (OM) analysis revealed the presence of bi-model neck-lace type grains and equiaxed grains as a result of different heat treatment conditions. Scanning electron microscopy (SEM) and elemental composition analysis revealed precipitates and second-phase particles. Carbides such as Ti (N, C) and (W, Mo, Ti) C were observed having different sizes and shapes. Cr-rich carbide phases were found to be preferentially segregated along the grain boundaries. X-ray diffraction analysis was carried out for assessing the phases present in the alloy. X-ray diffraction analysis revealed the gamma matrix and the precipitate phase are crystallographically identical (coherent). Transmission electron microscopic (TEM) analysis of the specimens confirmed the presence of uniformly distributed spherical Ni3 (Al, Ti) precipitates which impart thermal stability to the superalloy. Presence of different types of carbides is also revealed by TEM analysis.

Isolation pyro valves fabricated from AISI 321 austenitic stainless steel are performance-critical components used in launch vehicle propulsion systems. These valves isolate the fuel and oxidizer separated by a thin membrane that will be severed during its operation. As a part of the qualification program, a set of pyro valves were tested at the operating temperature of 20 K. During post-test examination of the hardware, membrane separation was not observed in one of the pyro valves tested. The failed and successfully tested valves were analysed to understand the reason for the non-separation of the pyro valve membrane. The present work brings out the details of metallurgical and mechanical aspects of the failed as well as successfully tested isolation pyro valves.

The optimized molecular structure, vibrational wavenumbers, corresponding vibrational assignments of 2-[4-(4-phenylbutanamido)phenyl]-5-ethylsulphonyl-benzoxazole have been investigated experimentally and theoretically using Gaussian09 software. The wavenumbers were assigned by potential energy distribution and the frontier molecular orbital analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The MEP analysis shows that the negative electrostatic potential regions are mainly localized over the oxygen's of the carbonyl and sulfonyl groups and nitrogen atom of the benzoxazole ring and are possible sites for electrophilic attack and the positive regions are localized over the NH group as possible sites for nucleophilic attack. From the molecular docking study, the ligand binds at the active sites of the protein by weak non-covalent interactions most prominent of which are H-bonding, cation-π and sigma-π interactions.

Bearing damages in reaction/momentum wheels are detrimental to the life and performance of the spacecraft. The signature of performance degradation in spacecraft ball bearings includes an increase in the bearing friction as evidenced by the increase in wheel current with a simultaneous increase in the wheel bearing temperature. The potential source of the problem should be addressed to avoid the irreversible impact on mission life. This paper presents the details of metallurgical analysis conducted on AISI 440C ball bearings to address the issues which perhaps contribute to the above problem and suggest possible remedial measures to avoid the recurrence of such issues. During ground testing, surface distress/running tracks were noticed on the contact surfaces of the balls. Detailed metallurgical analysis revealed loss of hard/coarse primary carbides from the matrix. In a closed system, these particles once removed, can contaminate the lubricant and cause further surface distress and progressive damage to the contact surface.

Lithium rich cathode materials with high specific capacity are considered as promising candidates for improving the energy density of lithium ion cells. In this paper, a Li-rich cathode material, Li1.5Ni0.25Mn0.75O2.5 with well-ordered layered structure is successfully synthesized using a simple carbonate co-precipitation method followed by calcination at 900 °C. The phase purity was studied by X-ray diffraction (XRD) and morphology was studied by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). SEM analysis of the material revealed cylinder-shaped particles with diameter in the range 100–350 nm. The electrochemical evaluation of the material reveals an initial specific capacity of ~240 mAhg−1 at C/20 rate.

The molecular structure, vibrational wave numbers, NLO, NBO, MEP and HOMO, LUMO analysis of 4-[2(5-Ethylpyridin-2-yl)ethoxy]benzaldehyde oxime were reported. The theoretically predicted geometrical parameters are in agreement with the XRD data. Using NBO analysis the change in the electron density in the anti-bonding orbital and stabilization energies have been calculated to give clear evidence of stabilization in the hyper-conjugation of hydrogen bonded interactions. The calculated first hyperpolarizability is 46.761 times that of the standard NLO material urea. From molecular electrostatic potential plot, phenyl ring, pyridine ring and oxygen atoms are the most electronegative regions and the hydrogen atom in the OH group is the most electropositive region. ALIE surfaces and Fukui functions have been calculated in order to obtain information related to the local reactivity properties of the title molecule. Intra-molecular non-covalent interactions have also been searched for. In order to investigate autoxidation and degradation properties we have calculated bond dissociation energies for all single acyclic bonds. To determine which atoms have the most pronounced interactions with water molecules we have conducted molecular dynamics simulations and calculated radial distribution functions. Molecular docking studies suggest that the title compound can be a lead compound for developing new anti-cancerous drug. (C) 2016 Elsevier B.V. All rights reserved.

IR and Raman spectra of 1-[3-(1H-imidazol-1-yl)propyl]-3-phenylthiourea (HIPPT) have been recorded in the solid phase and the vibrational wave numbers are calculated theoretically by B3LYP/6-31G(d,p) (6D, 7F) method. All the fundamental vibrational modes have been assigned using potential energy distribution values and the molecular structure was analyzed in terms of parameters like bond length, bond angles and dihedral angles. The ring breathing mode of the phenyl ring is observed at 1016 cm(-1) in the IR spectrum, 1014 cm(-1) in the Raman spectrum and at 1014 cm(-1) theoretically. The values of polarizability and hyperpolarizabilities were calculated and nonlinear optical properties are discussed. The HOMO-LUMO plot reveals the charge transfer possibilities in the molecule. The NBO analysis was computed and possible transitions were correlated with the electronic transitions. In the title compound, the imidazole ring and CH2 groups are tilted from each other and the thiourea group is tilted from the phenyl ring. Using MEP plot the electrophilic and nucleophilic regions are identified. Local reactivity properties were investigated by analysis of ALIE surfaces and Fukui functions. Oxidation and degradation properties were initially assessed by calculation of bond dissociation energies of all single acyclic bonds. Determination of atoms with pronounced interactions with water molecules was performed by calculation of radial distribution functions after molecular dynamics simulations. Chargehopping rates were calculated within Marcus semi-empiric approach, employing both DFT calculations and MD simulations. The molecular docking computational predictions were complemented by the in vitro antibacterial activity evaluation. (C) 2016 Elsevier B.V. All rights reserved.

The progress of surface-enhanced Raman scattering (SERS) substrates, which offers flexibility, improved sample collection efficiency and high SERS activity, has provided results in numerous applications. The present study demonstrates the development of a flexible substrate based on electrospun polystyrene (PS) nanofibers decorated with silver nanoparticles for in situ sampling and detection using SERS. The surface of the PS nanofibers contains uniformly distributed nanopores in the range of 70–100 nm due to the phenomenon called ‘breathe figure’. The nanoparticles are strongly adsorbed over the nanofiber surface due to the presence of these nanopores. The present substrate offers effective in situ sampling by wiping directly from the surface of luggage, fruits or any surface of interest. We demonstrated the SERS activity of the substrate by choosing highly energetic materials such as, RDX, DNT and pesticides, namely carbofuran. The results demonstrated that the nanoparticle coated electrospun PS nanofiber mats are promising for in situ sampling and SERS-based detection.

Gelatin nanofiber fabricated by electrospinning process is found to mimic the complex structural and functional properties of natural extracellular matrix for tissue regeneration. In order to improve the physico-chemical and biological properties of the nanofibers, graphene oxide is incorporated in the gelatin to form graphene oxide decorated gelatin nanofibers. The current research effort is focussed on the fabrication and evaluation of physico-chemical and biological properties of graphene oxide-gelatin composite nanofibers. The presence of graphene oxide in the nanofibers was established by transmission electron microscopy (TEM). We report the effect of incorporation of graphene oxide on the mechanical, thermal and biological performance of the gelatin nanofibers. The tensile strength of gelatin nanofibers was increased from 8.29±0.53MPa to 21±2.03MPa after the incorporation of GO. In order to improve the water resistance of nanofibers, natural based cross-linking agent, namely, dextran aldehyde was employed. The cross-linked composite nanofibers showed further increase in the tensile strength up to 56.4±2.03MPa. Graphene oxide incorporated gelatin nanofibers are evaluated for bacterial activity against gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria and cyto compatibility using mouse fibroblast cells (L-929 cells). The results indicate that the graphene oxide incorporated gelatin nanofibers do not prevent bacterial growth, nevertheless support the L-929 cell adhesion and proliferation.

Coaxial electrospinning is an upcoming technology that has emerged from the conventional electrospinning process in order to realize the production of nanofibers of less spinnable materials with potential applications. The present work focuses on the production of chitosan nanofibers in a benign route, using natural polymer as core template, mild solvent system and naturally derived cross-linkers. Nanofibers with chitosan as shell are fabricated by coaxial electrospinning with highly spinnable gelatin as core using aqueous acetic acid as solvent. For maintaining the biocompatibility and structural integrity of the core-shell nanofibers, cross-linking is carried out using naturally derived cross-linking agents, dextran aldehyde and sucrose aldehyde. The biological evaluation of gelatin/chitosan mat is carried out using human osteoblast like cells. The results show that the cross-linked core-shell nanofibers are excellent matrices for cell adhesion and proliferation.

Graphene oxide incorporated polymer matrix provides a multifunctional facet due to the reinforcing effect of graphene oxide (GO) with wide range of properties. Nanofibers are fabricated by a versatile technique known as electrospinning. The present study demonstrates the fabrication of gelatin, a protein nanofibers non-covalently functionalized with GO. The effect of GO on gelatin nanofibers in terms of mechanical performance is studied. In order to improve the water resistance of the resulting nanofibers, cross-linking is performed using dextran aldehyde.

Gelatin nanofibers were fabricated via electrospinning with minimal toxicity from solvents and cross-linking agents. Electrospinning was carried out using a solvent system based on water and acetic acid (8:2, v/v). Acetic acid concentration was kept as minimum as possible to reduce the toxic effects. Electrospun gelatin nanofibers were cross-linked with oxidized sucrose. Sucrose was oxidized by periodate oxidation to introduce aldehyde functionality. Cross-linking with oxidized sucrose could be achieved without compromising the nanofibrous architecture. Cross-linked gelatin nanofibers maintained the fibrous morphology even after keeping in contact with aqueous medium. The morphology of the cross-linked nanofibrous mats was examined by scanning electron microscopy (SEM). Oxidized sucrose cross-linked gelatin nanofibers exhibited improved thermal and mechanical properties. The nanofibrous mats were evaluated for cytotoxicity and cell viability using L-929 fibroblast cells. The results confirmed that oxidized sucrose cross-linked gelatin nanofibers were non-cytotoxic towards L-929 cells with good cell viability.

Gelatin based electrospun nanofibers are promising candidates for tissue engineering and regenerative medicine due to properties like biocompatibility, non antigenicity, non-toxicity and structural resemblance with native extracellular matrix. In the present work, a new nanofibrous scaffold using amine functionalized gelatin is fabricated. Modified gelatin is also known by the name cationized gelatin as the amino group is getting protonated. Unlike gelatin, the cationized gelatin is soluble in water without forming gel at room temperature. Hence, electrospinning of cationized gelatin can be carried out using water as the solvent. The water stability of cationized gelatin nanofibers is improved by cross-linking with two novel cross-linking agents, namely a disaccharide (sucrose) and a polysaccharide (dextran). The resulting cationized gelatin nanofibers are evaluated for the mouse fibroblast and human osteoblast like cells attachment, adhesion and proliferation. The results demonstrate that the electrospun cationized gelatin nanofibers can be potential scaffold materials for tissue regenerations.

Ba0.6 Sr0.4 TiO3 thin films are potential candidates for ferroelectric devices like Dynamic Random Access Memory (DRAM), microwave tunable devices, uncooled infrared detectors etc. For all such applications it is highly desirable to have BST film with lowest possible loss and leakage current with frequency independent dielectric properties. It is reported that bottom electrode of BST capacitor has high influence on such properties. In the present work, Ba0.6 Sr0.4 TiO3 thin films were deposited on LNO/Platinum layered bottom electrode on a Silicon wafer. Both LNO and BST were deposited using Chemical Solution Deposition method. For comparative study, BST films were also deposited on Pt electrode. The structural properties were investigated using X-Ray Diffraction and Atomic Force Microscopy. Electrical properties were studied using impedance analysis and IV characterization of the stacks. Both the films were found to be polycrystalline with smooth and crack-free surface. Electrical characterization reveal...

The vibrational wavenumbers, molecular structure, MEP, NLO, NBO and HOMO, LUMO analysis of Ethyl 2(4-oxo-3-phenethyl-3,4-dihydroquinazolin-2-ylthio)-acetate (EPDA) were reported. The change in electron density in the antibonding orbitals and stabilization energies have been calculated by NBO analysis to give clear evidence of stabilization in the hyperconjugation of hydrogen bonded interaction. The difference in HOMO and LUMO energy support the charge transfer interaction within the molecule. NMR studies and Fukui functions are also reported. From molecular electrostatic potential plot it is evident that the negative charge covers the carbonyl groups, phenyl rings and the positive region is over the CH2 groups with the acetate group. Molecular docking studies shows that the title compound forms a stable complex with pyrrole inhibitor and gives a binding affinity value of -8.3 kcal/mol and the results suggest that the compound might exhibit inhibitory activity against pyrrole inhibitor. (C) 2016 Elsevier B.V. All rights reserved.

Electrospun gelatin nanofibres attract attention of bioengineering arena because of its excellent biocompatibility and structural resemblance with native extracellular matrix. In this study, we have developed gelatin nanofibres using an innovative cross-linking approach to minimize cytotoxic effects. Gelatin was dissolved in water:acetic acid (8:2, v/v) solution and electrospun to form nanofibres with diameter in the range of 156 ± 30 nm. The nanofibres were cross-linked with a modified polysaccharide, namely, dextran aldehyde (DA). Cross-linking with DA could be achieved without compromising the fibrous architecture. DA cross-linked gelatin nanofibres maintained the fibrous morphology in aqueous medium. These mats exhibit improved mechanical properties and gradual degradation behaviour. The nanofibres were evaluated for cytotoxicity, cell adhesion, viability, morphology and proliferation using L-929 fibroblast cells. The results confirmed that DA cross-linked mats were non cytotoxic towards L-929 cells with good cell adhesion, spreading and proliferation.

In the recent years, the use of phytoremediation for ameliorating metal pollution has been gaining ground. This study explores the. possibility of utilising two common aquatic ferns, Salvinia molesta Mitchell and Azolla rubra R.Br. for scavenging chromium from solutions. Chromium removal from spiked solutions ranged from 40-99% during the seven day exposure. Results reveal their bioremoval capabilities and potentialfor use in wastewater decontaminant

Colour and texture are the most common features used in CBIR systems today. In this paper, we wish to investigate structural methods of texture analysis for CBIR in view of their closeness to human perception and description of texture. In structural analysis, local patterns are the key (as is the case with humans), and when used as features may be expected to return more relevant images in CBIR. One method to describe local patterns in computationally simple terms is texture spectrum proposed by He and Wang. In this paper, we propose two additional characterizations of local patterns. The first is an extension of He and Wang's texture spectrum to larger and more meaningful windows, along with new structural features that capture local patterns such as horizontal and vertical stripes, alternating dark and bright spots, etc. The second is a new method that characterizes patterns as contrast variations in 5 /spl times/ 5 windows. We apply the new texture characterizations to develop a CBIR application and tested their performance on two databases containing remote sensing images. Our results show accuracies that range from 60% to 100% depending on the query image and the features contained therein. These results indicate that our texture features are useful in retrieving images appropriate for different remote sensing applications.

Kerala state occupies the south-west part of India, between 8° 17′ 30″ and 12° 47′ 40″ north latitude and 74° 51′ to 77°24′ 47″ east longitude. The majestic western ghats and the Arabian sea on the west have given Kerala distinctive physical and cultural features. Kerala enjoys a tropical monsoon climate and receives good monsoon rains i.e., south-west monsoon [June–September] and north-east monsoon [October–December]. The average rainfall is about 3000 Mm. The state, with a total area of 38,863 sq. km, has a groundwater potential of 5000 Mm3. Even though it receives fairly good average rainfall, bulk of our rural population depend on groundwater for multipurpose activities.