Surface charge induced tuning of electrical properties of CVD assisted graphene and functionalized graphene sheets

We demonstrate a new approach to tune the electrical properties of graphene and functionalized graphene. Graphene was synthesized using thermal chemical vapour deposition(TCVD) method on copper foil using precursor gas acetylene and co-catalyst H2 gas. TCVD assisted graphene was successfully transferred onto a silicon wafer. Transferred graphene sheet was then functionalized to prepare graphene oxide(GO) and reduced graphene oxide(rGO). Different surface charge carbon nanoparticles, e.g. carbon nanoparticle with net positive charge and carbon nanoparticle with net negative charge were then immobilized on transferred graphene and functionalized graphene sheets. The functionalized graphene and charge mobilized functionalized graphene were characterized by Uv–vis spectroscopy,Fourier transformed infrared spectroscopy, scanning electron microscopy, and Raman spectroscopy. After immobilization of carbon nanomaterials, the ac electrical conductivity was found to increase due to enhancement of the surface charge, electron density, and mobility. It was observed that negative surface charge immobilized graphene and functionalized graphene show higher conductivity. Thus, the electrical property of graphene and functionalized graphene can be tuned by surface modification with different surface charge carbon nanomaterials.     

CYP1B1 Augments the Mesenchymal,Claudin-Low,and Chemoresistant Phenotypes of Triple-Negative Breast Cancer Cells

Cytochrome P4501B1 (CYP1B1) is elevated in breast cancer. Studies indicate a relationship between CYP1B1 and aggressive cancer phenotypes. Here, we report on in vitro studies in triple-negative breast cancer cell lines, where knockdown (KD) of CYP1B1 was used to determine the influence of its expression on invasive cell phenotypes. CYP1B1 KD in MDA-MB-231 cells resulted in the loss of mesenchymal morphology, altered expression of epithelial–mesenchymal genes, and increased claudin (CLDN) RNA and protein. CYP1B1 KD cells had increased cell-to-cell contact and paracellular barrier function, a reduced rate of cell proliferation, abrogation of migratory and invasive activity, and diminished spheroid formation. Analysis of clinical breast cancer tumor samples revealed an association between tumors exhibiting higher CYP1B1 RNA levels and diminished overall and disease-free survival. Tumor expression of CYP1B1 was inversely associated with CLDN7 expression, and CYP1B1^HI/CLDN7^LOW identified patients with lower median survival. Cells with CYP1B1 KD had an enhanced chemosensitivity to paclitaxel, 5-fluorouracil, and cisplatin. Our findings that CYP1B1 KD can increase chemosensitivity points to therapeutic targeting of this enzyme. CYP1B1 inhibitors in combination with chemotherapeutic drugs may provide a novel targeted and effective approach to adjuvant or neoadjuvant therapy against certain forms of highly metastatic breast cancer.     

Combined experimental and analytical method for a realistic seismic qualification of equipment

The seismic qualification of equipment/structures are, in general, carried out either exclusively by analysis or exclusively by testing using a shake table. The analytical methods have the risk of the model not being a true reflection of the structure unless very elaborate modelling techniques are used. Even with an elaborate model there are many idealisations made which may not actually be realised in practice. The shake-table testing, avoids the modelling deviations to a large extent, but is also not without drawbacks. The important ones are the cost and the availability of a shake table of the required size and capacity. The shake-table testing is also carried out on the isolated equipment without the piping/structural connections from other components. The present paper suggests a combined experimental and analytical method on the ‘as installed’ equipment as an attractive alternative which overcomes the above drawbacks. In contrast to the existing practice of using the experimental results just to validate the analytical model, the suggested method uses the experimentally obtained dynamic characteristics of the ‘as installed’ equipment to obtain the response to the design seismic load. The paper brings out through an example of a simple storage tank which is too heavy for a shake table, the large deviations in its actual behaviour vis-à-vis an idealised analytical model.     

Luminescence properties of Eu3+- and Tb3+-doped δ-Bi2O3 stabilized by Th4+ substitution

The extent of incorporating Eu³⁺ and Tb³⁺ for bismuth in the oxygen-deficient fluorite structured Bi_0.50Th_0.50O_y has been examined together with the comprehension of their luminescence characteristics. The samples were synthesized by solution combustion method from which doping limits of Eu³⁺ and Tb³⁺, respectively, in the fluorite structure was determined. Uniform distribution of constituent elements was confirmed from elemental mapping. Doping Eu³⁺ and Tb³⁺-ions introduced compressive strain and oxygen vacancies in the system. Raman spectra of doped samples confirmed the fluorite structure and revealed the existence of oxygen vacancies in them. While Tb-doped samples showed a systematic decrease in band gap with increase in dopant concentration, such systematic variation was not observed for Eu-doped samples. Conclusions about the local site symmetry around Eu³⁺ and Tb³⁺ ions in the defect fluorite structure have been drawn from the photoluminescent spectral analysis of doped samples. Energy transfer from Bi³⁺ to Eu³⁺ and Tb³⁺-has been observed in these samples. The Judd-Ofelt analysis has been carried out to understand luminescence characteristics in these samples.     

Cactus cladode polysaccharide as cryoprotectant in frozen Paneer (Indian Cottage Cheese)

The study investigated the optimisation of freezing conditions for Paneer (Indian cottage cheese) incorporated with cactus cladode polysaccharide as cryoprotectant. The freezing rate of both natural and commercial cryoprotectant‐containing samples varied significantly. The optimised (2% natural cryoprotectant) Paneer sample had about 44% moisture content, 14% protein, 16% carbohydrate and 22% fat. Freezing time of optimised Paneer sample packed in metalised polyester was 40 min. The study concluded that Paneer incorporated with 2% cactus cladode polysaccharide, packaged using metalised polyester and frozen with packaged immersion freezing method, had the least freezing time (40 min) and retained better texture during freezing.     

A computationally efficient model for determining sound speed in shallow tropical freshwater systems,with field validation

The optimum performance of any underwater system depends on the propagation characteristics of the acoustic signals in the local water medium. Shallow tropical freshwater systems suffer from sub‐optimal performance of sonar systems deployed for any acoustic sensing because of random fluctuations of the water medium. The propagation characteristics depend largely on the sound speed variations defined by the site‐specific physical parameters such as water temperature, salinity and depth. The present study focuses on analysing the sound speed profile of a typical shallow freshwater system (Khadakwasla Lake; 18.43°N, 73.76°E), using regression models with the goal of deriving a computationally efficient model. To this end, a linear and polynomial regression model was developed, and their performance compared with the results of the model of Chen and Millero ( 1977 ), based on root mean square error (RMSE). In situ measurements of electrical conductivity, temperature and density (CTD) were carried out using a Valeport 602 CTD meter. Approximately 125 CTD samples were obtained during a 2‐day experimental study conducted at Khadakwasla Lake from 11 October 2017 to 12 October 2017. The data collection was undertaken throughout the day at multiple locations in the lake over a spatial distance of ~16 km. The Valeport 602 CTD meter uses the Chen and Millero ( 1977 ) formula, considered the most conventional sound speed equation. The computational complexity of the proposed models was measured in terms of the number of addition and multiplication operations required. The validation of both models was carried out by varying the model input parameters within defined limits. The model inputs have been derived from an in situ experimental data collection process in a typical shallow tropical freshwater system. The linear regression model exhibited an RMSE of 4.15 m/s, while the polynomial regression model exhibited a good agreement with an RMSE of 0.5 m/s.     

Dynamic mechanical analysis and interpretation of molecular motions in polyarylates

Molecular motions in polyarylates synthesized from substituted bisphenols have been investigated by dynamic mechanical analysis. Substitution at the ring carbon atom results in a more pronounced enhancement in glass transition temperature (T_g) as compared to substitution at the bridge carbon atom. The enhancement in mono and disubstituted polyarylates is more consistent than that in the case of polycarbonates and polysulfones. The β transition has been shown to result from defects in the polymer samples. The molecular motion responsible for the τ transition in polyarylates has been shown to be more iocalized than in the case of polycarbonates. Introduction of the phthalide ring in the isopropylidene unit of bisphenol-A molecule results in splitting of the τ transition peak into two. The results have been compared with those reported for other bisphenol-based polymers, viz. polycarbonates and polysulfones, and explained on the basis of the structural attributes of the polymers. © 1994 John Wiley & Sons, Inc.     

Microstructural Analysis in Processing of the High-Tc Superconductor Ba2YCu3O7-x in Air

In the synthesis of the superconducting compound Ba₂YCu₃O_7-x from a stoichiometric mixture containing BaCO₃, Y₂O₃, and CuO In air, a low-melting liquid phase is formed at about 890°C. The liquid phase was identified as a ternary eutectic located within the compatibility triangle Ba₂YCu₃O_7-x–BaCuO₂–CuO. The implication of this finding for the processing of Ba₂YCu₃O_7-x is discussed.     

Rotational invariance of two-level group codes over dihedral and dicyclic groups

Phase-rotational invariance properties for two-level constructed, (using a binary code and a code over a residue class integer ring as component codes) Euclidean space codes (signal sets) in two and four dimensions are discussed. The label codes are group codes over dihedral and dicyclic groups respectively. A set of necessary and sufficient conditions on the component codes is obtained for the resulting signal sets to be rotationally invariant to several phase angles.