Non-destructive evaluation of porosity and its effect on mechanical properties of carbon fiber reinforced polymer composite materials

Structural adhesive bonding is widely used to execute assemblies in automobile and aerospace structures. The quality and reliability of these bonded joints must be ensured during service. In this context non destructive evaluation of these bonded structures play an important role. Evaluation of adhesively bonded composite single lap shear joints has been attempted through experimental approach. Series of tests, non-destructive as well as destructive were performed on different sets of carbon fiber reinforced polymer (CFRP) composite lap joint specimens with varied bond quality. Details of the experimental investigations carried out and the outcome are presented in this paper.

Parameter estimation of a two-horizon soil profile by combining crop canopy and surface soil moisture observations using GLUE

Estimation of soil parameters by inverse modeling using observations on either surface soil moisture or crop variables has been successfully attempted in many studies, but difficulties to estimate root zone properties arise when heterogeneous layered soils are considered. The objective of this study was to explore the potential of combining observations on surface soil moisture and crop variables - leaf area index (LAI) and above-ground biomass for estimating soil parameters (water holding capacity and soil depth) in a two-layered soil system using inversion of the crop model STICS. This was performed using GLUE method on a synthetic data set on varying soil types and on a data set from a field experiment carried out in two maize plots in South India. The main results were (i) combination of surface soil moisture and above-ground biomass provided consistently good estimates with small uncertainity of soil properties for the two soil layers, for a wide range of soil paramater values, both in the synthetic and the field experiment, (ii) above-ground biomass was found to give relatively better estimates and lower uncertainty than LAI when combined with surface soil moisture, especially for estimation of soil depth, (iii) surface soil moisture data, either alone or combined with crop variables, provided a very good estimate of the water holding capacity of the upper soil layer with very small uncertainty whereas using the surface soil moisture alone gave very poor estimates of the soil properties of the deeper layer, and (iv) using crop variables alone (else above-ground biomass or LAI) provided reasonable estimates of the deeper layer properties depending on the soil type but provided poor estimates of the first layer properties. The robustness of combining observations of the surface soil moisture and the above-ground biomass for estimating two layer soil properties, which was demonstrated using both synthetic and field experiments in this study, needs now to be tested for a broader range of climatic conditions and crop types, to assess its potential for spatial applications. (C) 2012 Elsevier B.V. All rights reserved.

Novel De-Acylative Ring Opening of 3-Acetyl and 3-Bromo Acetyl Coumarins

Reaction of 3-acetyl and 3-bromoacetyl coumarins with hydrazine hydrate has resulted in the ring opening of the coumarin moiety. The reaction was attempted with a view to obtain some new pyridazinones and pyrazolones. The reaction did not proceed via the expected pathway instead led to the formation of salicyl azines, the structure of which has been confirmed by single crystal X-ray studies.

Conformational Polymorphism in a Non-steroidal Anti-inflammatory Drug, Mefenamic Acid

For several years, the non-steroidal anti-inflammatory drug mefenamic acid, MA, has been known to exist as dimorphs (I and II). We report a new metastable polymorph (III) of MA obtained during attempted co-crystallization experiments and establish its stability relationship with existing forms. At elevated temperatures I and III convert to II, as evident from DSC experiments. On the basis of the lattice energy calculations in conjunction with thermal analysis, the stability order is proposed to be I > II > III at ambient conditions, whereas at elevated temperature the order is II > I > III. In either condition III is a metastable form and hence transforms to I at ambient conditions and to II at higher temperatures. Also we report the structural studies of a DMF solvate and a cytosine complex.

Polymer microfabrication by scanning based microstereolithography: Optical design and material functionality

Several research groups have attempted to optimize photopolymerization parameters to increase the throughput of scanning based microstereolithography (MSL) systems through modified beam scanning techniques. Efforts in reducing the curing line width have been implemented through high numerical aperture (NA) optical setups. However, the intensity contour symmetry and the depth of field of focus have led to grossly non-vertical and non-uniform curing profiles. This work tries to review the photopolymerization process in a scanning based MSL system from the aspect of material functionality and optical design. The focus has been to exploit the rich potential of photoreactor scanning system in achieving desired fabrication modalities (minimum curing width, uniform depth profile, and vertical curing profile) even with a reduced NA optical setup and a single movable stage. The present study tries to manipulate to its advantage the effect of optimized lower c] (photoinitiator (PI) concentration) in reducing the minimum curing width to similar to 10-20 mu m even with a higher spot size (similar to 21.36 mu m) through a judiciously chosen ``monomer-PI'' system. Optimization on grounds of increasing E-max (maximum laser exposure energy at surface) by optimizing the scan rate provides enough time for the monomer or resin to get cured across the entire resist thickness (surface to substrate similar to 10-100 mu m), leading to uniform depth profiles along the entire scan lengths. (C) 2012 American Institute of Physics. http://dx.doi.org/10.1063/1.4750975]

On the basin-scale detection and attribution of human-induced climate change in monsoon precipitation and streamflow

Detecting and quantifying the presence of human-induced climate change in regional hydrology is important for studying the impacts of such changes on the water resources systems as well as for reliable future projections and policy making for adaptation. In this article a formal fingerprint-based detection and attribution analysis has been attempted to study the changes in the observed monsoon precipitation and streamflow in the rain-fed Mahanadi River Basin in India, considering the variability across different climate models. This is achieved through the use of observations, several climate model runs, a principal component analysis and regression based statistical downscaling technique, and a Genetic Programming based rainfall-runoff model. It is found that the decreases in observed hydrological variables across the second half of the 20th century lie outside the range that is expected from natural internal variability of climate alone at 95% statistical confidence level, for most of the climate models considered. For several climate models, such changes are consistent with those expected from anthropogenic emissions of greenhouse gases. However, unequivocal attribution to human-induced climate change cannot be claimed across all the climate models and uncertainties in our detection procedure, arising out of various sources including the use of models, cannot be ruled out. Changes in solar irradiance and volcanic activities are considered as other plausible natural external causes of climate change. Time evolution of the anthropogenic climate change ``signal'' in the hydrological observations, above the natural internal climate variability ``noise'' shows that the detection of the signal is achieved earlier in streamflow as compared to precipitation for most of the climate models, suggesting larger impacts of human-induced climate change on streamflow than precipitation at the river basin scale.

Calibration and linearity verification of capacitance type cryo level indicators using cryogenically multiplexed diode array

In space application the precision level measurement of cryogenic liquids in the storage tanks is done using triple redundant capacitance level sensor, for control and safety point of view. The linearity of each sensor element depends upon the cylindricity and concentricity of the internal and external electrodes. The complexity of calibrating all sensors together has been addressed by two step calibration methodology which has been developed and used for the calibration of six capacitance sensors. All calibrations are done using Liquid Nitrogen (LN2) as a cryogenic fluid. In the first step of calibration, one of the elements of Liquid Hydrogen (LH2) level sensor is calibrated using 700mm eleven point discrete diode array. Four wire method has been used for the diode array. Thus a linearity curve for a single element of LH2 is obtained. In second step of calibration, using the equation thus obtained for the above sensor, it is considered as a reference for calibrating remaining elements of the same LH2 sensor and other level sensor (either Liquid Oxygen (LOX) or LH2). The elimination of stray capacitance for the capacitance level probes has been attempted. The automatic data logging of capacitance values through GPIB is done using LabVIEW 8.5.

Influence of growth ambience and doping on the structural properties of multiferroic DyMnO3

We report on the single crystal growth of 50% Sr and Y doped multiferroic DyMnO3 using optical floating zone technique. A comparison of the effect of growth ambience and of chemical substitution on the crystal structure of DyMnO3 is attempted. It is observed that DyMnO3 adopts Pm3m cubic structure with 50% Sr doping whereas with 50% Y doping, the crystal structure is hexagonal P6(3)cm. Orthorhombic Pnma structure is adopted by DyMnO3 when grown in air, whereas hexagonal P6(3)cm structure is obtained when grown under the ambience of argon. The structural polymorphism is discussed in terms of difference in ionic sizes of Sr, Y and Dy, comparable Gibbs free energies and coordination schemes of surrounding oxygens for hexagonal and orthorhombic structures of DyMnO3. (C) 2012 Elsevier B.V. All rights reserved.

Development of a New Generation of Vectors for Gene Expression, Gene Replacement, and Protein-Protein Interaction Studies in Mycobacteria

Escherichia coli-mycobacterium shuttle vectors are important tools for gene expression and gene replacement in mycobacteria. However, most of the currently available vectors are limited in their use because of the lack of extended multiple cloning sites (MCSs) and convenience of appending an epitope tag(s) to the cloned open reading frames (ORFs). Here we report a new series of vectors that allow for the constitutive and regulatable expression of proteins, appended with peptide tag sequences at their N and C termini, respectively. The applicability of these vectors is demonstrated by the constitutive and induced expression of the Mycobacterium tuberculosis pknK gene, coding for protein kinase K, a serine-threonine protein kinase. Furthermore, a suicide plasmid with expanded MCS for creating gene replacements, a plasmid for chromosomal integrations at the commonly used L5 attB site, and a hypoxia-responsive vector, for expression of a gene(s) under hypoxic conditions that mimic latency, have also been created. Additionally, we have created a vector for the coexpression of two proteins controlled by two independent promoters, with each protein being in fusion with a different tag. The shuttle vectors developed in the present study are excellent tools for the analysis of gene function in mycobacteria and are a valuable addition to the existing repertoire of vectors for mycobacterial research.

Correlation between corona current and radio interference due to high voltage insulator string

The Radio Interference (RI) from electric power transmission line hardware, if not controlled, poses serious electromagnetic interference to system in the vicinity. The present work mainly concerns with the RI from the insulator string along with the associated line hardware. The laboratory testing for the RI levels are carried out through the measurement of the conducted radio interference levels. However such measurements do not really locate the coronating point, as well as, the mode of corona. At the same time experience shows that it is rather difficult to locate the coronating points by mere inspection. After a thorough look into the intricacies of the problem, it is ascertained that the measurement of associated ground end currents could give a better picture of the prevailing corona modes and their intensities. A study on the same is attempted in the present work. Various intricacies of the problem,features of ground end current pulses and its correlation with RI are dealt with. Owing to the complexity of such experimental investigations, the study made is not fully complete nevertheless it seems to be first of its kind.

Identification of prospective locations for generation expansion with least augmentation of network

With ever increasing demand for electric energy, additional generation and associated transmission facilities has to be planned and executed. In order to augment existing transmission facilities, proper planning and selective decisions are to be made whereas keeping in mind the interests of several parties who are directly or indirectly involved. Common trend is to plan optimal generation expansion over the planning period in order to meet the projected demand with minimum cost capacity addition along with a pre-specified reliability margin. Generation expansion at certain locations need new transmission network which involves serious problems such as getting right of way, environmental clearance etc. In this study, an approach to the citing of additional generation facilities in a given system with minimum or no expansion in the transmission facility is attempted using the network connectivity and the concept of electrical distance for projected load demand. The proposed approach is suitable for large interconnected systems with multiple utilities. Sample illustration on real life system is presented in order to show how this approach improves the overall performance on the operation of the system with specified performance parameters.

Comparison of North American universities with and without medical schools and their technology transfer initiatives

Empirical research available on technology transfer initiatives is either North American or European. Literature over the last two decades shows various research objectives such as identifying the variables to be measured and statistical methods to be used in the context of studying university based technology transfer initiatives. AUTM survey data from years 1996 to 2008 provides insightful patterns about the North American technology transfer initiatives, we use this data in our paper. This paper has three sections namely, a comparison of North American Universities with (n=1129) and without Medical Schools (n=786), an analysis of the top 75th percentile of these samples and a DEA analysis of these samples. We use 20 variables. Researchers have attempted to classify university based technology transfer initiative variables into multi-stages, namely, disclosures, patents and license agreements. Using the same approach, however with minor variations, three stages are defined in this paper. The first stage is to do with inputs from R&D expenditure and outputs namely, invention disclosures. The second stage is to do with invention disclosures being the input and patents issued being the output. The third stage is to do with patents issued as an input and technology transfers as outcomes.

Tuning ultrafast photoresponse of gold nanorods

Nondegenerate pump probe differential transmission experiments on gold nanorods with varying longitudinal surface plasmon resonance have revealed a new phenomenon where the polarity of the transient transmission signal can be reversibly switched between photo bleaching and photo-induced absorption by controlling probe fluence. Under the usual case where probe fluences are nominal, photo bleaching effect is observed for the nanorods with longitudinal surface plasmon resonance energy smaller than the probe photon energy. The laser-induced melting of the nanorods or change in their shape is ruled out for the observed optical switching effect. A quantitative understanding of the results is attempted by invoking a cascaded two-photon absorption dominant beyond a threshold probe fluence of similar to 75 mu J/cm(2).

Identification of immuno-dominant antigens of Trypanosoma evansi for detection of chronic trypanosomosis using experimentally infected equines

Trypanosoma evansi is the most extensively distributed trypanosome responsible for disease called surra in livestock in many countries including frequent outbreaks in India. The prevalence of this disease is most commonly reported by standard parasitological detection methods (SPDM); however, antibody ELISA is being in practice by locally produced whole cell lysate (WCL) antigens in many countries. In the present investigation, we attempted to identify and purify immuno dominant, infection specific trypanosome antigens from T. evansi proteome using experimentally infected equine serum by immuno blot. Three immuno dominant clusters of proteins i.e. 62-66 kDa, 52-55 kDa and 41-43 kDa were identified based on their consistent reactivity with donkey sequential serum experimentally infected T. evansi up to 280 days post infection (dpi). The protein cluster of 62-66 kDa was purified in bulk in native form and comparatively evaluated with whole cell lysate antigen (WCL). ELISA and immuno blot showed that polypeptide of this cluster is 100% sensitive in detection of early and chronic infection. Further, this protein cluster was also found immuno reactive against hyper immune serum raised against predominantly 66 kDa exo antigen, revealed that this is a common immunodominant moieties in proteome and secretome of T. evansi.

Morphing fixed wing MAV modeling using VAM

The design and implementation of a morphing Micro Air Vehicle (MAV) wing using a smart composite is attempted in this research work. Control surfaces actuated by traditional servos are difficult to instrument and fabricate on thin composite-wings of MAVs. Piezoelectric Fiber Reinforced Composites (PFRCs) are the chosen smart structural materials in the current work for incorporation onto fixed-wing MAVs to simultaneously perform the dual functions of structural load-bearing and actuation of flexure, torsion and/or extension for morphing. Further, PFRC use can be extended towards shape control of a “fixed” wing MAV to meet changing performance requirements. Wings that can warp into desired shapes and/or have variable camber are well-known to exhibit improved efficiency in aerodynamic control. During an entire flight cycle, there are multiple optimal configurations, each of which suits a particular phase of the flight regime. Widely proposed methods of wing morphing include changes in camber, twist, sweep and span. However, camber change during flight is already established, in terms of its potential, as a major factor in improving the aerofoil efficiency and flow separation behavior. Hence, for this work, morphing with camber change is adopted with the goal to better tailor aerodynamic properties.