Publications by authors named "Dhara S"

Correction for 'Experimental studies on the rheology of cubic blue phases' by Rasmita Sahoo et al., Soft Matter, 2016, DOI: .

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A fast one step bio-synthesis for in situ preparation of silver nanoparticles is proposed. The method involves reduction of AgNO3 with an aqueous extract of peanut skin, which is a good source of polyphenols. The silver nanoparticles thus synthesized were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-Vis absorption spectroscopy, Fourier Transform infrared (FTIR) spectroscopy and magnetic measurements.

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We report experimental studies on the Saturn ring defect associated with a spherical microparticle across the nematic (N) to smectic-A (SmA) phase transition. We observe that the director distortion around the microparticle changes rapidly with temperature. The equilibrium interparticle separation and the angle between two quadrupolar particles in the N phase are larger than those of the SmA phase.

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We report detailed experimental studies on the rheology of cubic blue phases. We observe several flow regimes within each blue phase from rheomicroscopy and small angle light scattering experiments. Both the cubic blue phases exhibit solid-like response while the cholesteric phase shows gel-like behavior.

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Article Synopsis
  • The new guidewire-assisted tracheal intubation system aims to address issues like technical difficulties and complications caused by traditional methods.
  • A reinforced silicone tracheal tube with a built-in guide channel and nitinol guidewire was tested against existing methods, showing less resistance in anatomical configurations.
  • While the new system required more force for intubation in certain situations, it ultimately promises to simplify the intubation process in patients, making it more reliable.
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A total reflection X-ray fluorescence (TXRF) analysis method for direct compositional characterization of sintered and green (U,Th)O2 samples in different forms (e.g., pellets, powders, and microspheres) without sample dissolution has been developed for the first time.

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Bio-conjugation or functional group substitutions are well-explored methods to enhance the physico-chemical and biochemical functionality of chitosan. N-Methylene phosphonic chitosan (NMPC) is one of the major substituted forms of chitosan, which has significant bioactivity and promising biomedical application. However, the reported synthesis methods of NMPC have limitations alike poor yield, higher degradation rate and most importantly long synthesis time (∼14h).

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Colloidal self-assembly has been one of the major driving themes in material science to obtain functional and advanced optical materials with complex architecture. Most of the nematic colloids reported so far are based on the optically isotropic spherical microparticles. We study organic single crystal micro-sheets and investigate their orientation, interaction and directed assembly in a nematic liquid crystal.

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Degradation and denaturation of labile biomolecules during preparation of micelles by organic solvent at high temperature are some of the limitations for fabrication of advanced polymer based protein delivery systems. In this paper, effectiveness of heat-chill method for preparation of micelles containing large labile biomolecules was investigated using insulin as a model protein molecule. Micelles (average size, <120 nm) were prepared using amphiphilic diblock and triblock copolymers of poly(ethylene glycol) (PEG) and poly(ϵ-caprolactone) (PCL).

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Electronic bands in crystals can support nontrivial topological textures arising from spin-orbit interactions, but purely orbital mechanisms can realize closely related dynamics without breaking spin degeneracies, opening up applications in materials containing only light elements. One such application is the circular photogalvanic effect (CPGE), which is the generation of photocurrents whose magnitude and polarity depend on the chirality of optical excitation. We show that the CPGE can arise from interband transitions at the metal contacts to silicon nanowires, where inversion symmetry is locally broken by an electric field.

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A novel stimulus-sensitive covalently cross-linked hydrogel derived from dextrin, N-isopropylacrylamide, and N,N'-methylene bis(acrylamide) (c-Dxt/pNIPAm), has been synthesized via Michael type addition reaction for controlled drug release application. The chemical structure of c-Dxt/pNIPAm has been confirmed through Fourier transform infrared (FTIR) spectroscopy and (1)H and (13)C NMR spectral analyses. The surface morphology of the hydrogel has been studied by field emission scanning electron microscopic (FE-SEM) and environmental scanning electron microscopic (E-SEM) analyses.

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Highly fluorescent Au(I)@Ag particles (emission maximum at 635 nm) have been obtained from a mixture of AgNO3, HAuCl4 and glutathione. Au(I)@Ag particles containing Ag2 and Ag3 clusters are produced when the reaction mixture is subjected to a modified hydrothermolysis (MHT) reaction. The silver clusters make the solution intensely fluorescent and the Au(I) moiety provides long term stability to the silver clusters by withdrawing electron density from the silver clusters.

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We observe that topological defects in nematic colloids are strongly influenced by the elasticity and onset of smectic layering across the nematic (N) to smectic-A (SmA) phase transition. When approaching the SmA phase from above, the nematic hyperbolic hedgehog defect that accompanies a spherical colloidal inclusion is transformed into a focal conic line in the SmA phase. This phase transformation has a strong influence on the pairwise colloidal interaction and is responsible for a structural transition of two-dimensional colloidal crystals.

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A simple and practical one-pot, two-directional approach to access olefinic esters through simultaneous breaking and making of olefins using ozonolysis of alkenyl aryl selenides is disclosed. The scope of the method with a variety of examples is demonstrated, and the end products obtained here are useful building blocks. As a direct application of the present method, the macrocyclic core of potent anti-inflammatory natural cyclic peptides, solomonamides, is synthesized.

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Hedgehog (Hh) signaling pathway is a valid therapeutic target in a wide range of malignancies. We focus here on glioblastoma multiforme (GBM), a lethal malignancy of the central nervous system (CNS). By analyzing RNA-sequencing based transcriptomics data on 149 clinical cases of TCGA-GBM database we show here a strong correlation (r = 0.

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We report, for the first time, the luminescence property of the hydroxyl group surface functionalized quantum dots (QDs) and nanoparticles (NPs) of SnO2 using low energy excitations of 2.54 eV (488 nm) and 2.42 eV (514.

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We demonstrate the graphene assisted catalyst free growth of ZnO nanowires (NWs) on chemical vapor deposited (CVD) and chemically processed graphene buffer layers at a relatively low growth temperature (580 °C) in the presence and absence of ZnO seed layers. In the case of CVD graphene covered with rapid thermal annealed ZnO buffer layer, the growth of vertically aligned ZnO NWs takes place, while the direct growth on CVD graphene, chemically derived graphene (graphene oxide and graphene quantum dots) without ZnO seed layer resulted in randomly oriented sparse ZnO NWs. Growth mechanism was studied from high resolution transmission electron microscopy and Raman spectroscopy of the hybrid structure.

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The ability to understand and model the performance limits of nanowire transistors is the key to the design of next generation devices. Here, we report studies on high-mobility junctionless gate-all-around nanowire field effect transistor with carrier mobility reaching 2000 cm(2)/V·s at room temperature. Temperature-dependent transport measurements reveal activated transport at low temperatures due to surface donors, while at room temperature the transport shows a diffusive behavior.

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Herein, novel biodegradable, stimulus-responsive, chemically cross-linked and porous hydrogel has been synthesized to evaluate its applicability as an efficient carrier for sustained release of ornidazole and ciprofloxacin. The cross-linked hydrogel (c-Dxt/pAA) has been developed from dextrin and poly(acrylic acid) using N,N'-methylene bis(acrylamide) cross-linker via Michael-type addition reaction. With the variation of reaction parameters, various c-Dxt/pAA hydrogels have been synthesized to optimize the best one.

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Psoriasis is a chronic inflammatory disease associated with an increased insulin resistance, obesity and cardiovascular risk. The present study was aimed to assess insulin resistance and pattern of body fat deposition in psoriasis. Body mass index (BMI) and waist circumference (WC) were measured in 40 psoriatic patients and 46 age- and sex-matched control subjects.

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Neoplastic cells of Glioblastoma multiforme (GBM) may or may not show sustained response to temozolomide (TMZ) chemotherapy. We hypothesize that TMZ chemotherapy response in GBM is predetermined in its neoplastic clones via a specific set of mutations that alter relevant pathways. We describe exome-wide enrichment of variant allele frequencies (VAFs) in neurospheres displaying contrasting phenotypes of sustained versus reversible TMZ-responses in vitro.

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Cell proliferation, cell morphology and protein adsorption on near β-type Ti-13Zr-13Nb (TZN) alloy and Ti-13Zr-13Nb-0.5B (TZNB) composite have been investigated and compared to evaluate the effect of boron addition which has been added to the Ti alloy to improve their poor tribological properties by forming in situ TiB precipitates. MG63 cell proliferation on substrates with different chemistry but the same topography was compared.

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Chitosan fibers were prepared in citric acid bath, pH 7.4 and NaOH solution at pH 13, to form ionotropically cross-linked and uncross-linked fibers, respectively. The fibers formed in citric acid bath were further cross-linked via carbodiimide chemistry; wherein the pendant carboxyl moieties of citric acid were used for new amide bond formation.

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We prepared nanocomposites of a nematic liquid crystal and nanofibers of a conducting polymer (polyaniline). All the nanocomposites exhibit a discontinuous surface anchoring transition from planar to homeotropic in the nematic phase on a perfluoropolymer coated surface with a thermal hysteresis (≈ 5.3 °C).

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We report experimental studies on the rheology of a few nematic liquid crystals with highly polar molecules (CCH-7, PCH-7, CB-7). The selected molecules have the same alkyl chain (-C(7)H(15)) and cyano (-CN) end group. In the core part of the molecule, CCH-7 has two cyclohexane rings, PCH-7 has one cyclohexane and one aromatic ring, and CB-7 has two aromatic rings.

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