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641.
Ashok M Kalkura SN Sundaram NM Arivuoli D 《Journal of materials science. Materials in medicine》2007,18(5):895-898
Hydroxyapatite crystals were grown by hydrothermal method using dicalcium phosphate dihydrate crystals as a starting material.
The grown crystals were found to be free from carbonate inclusion. Two distinct morphologies were obtained by following two
different growth methods. Controlled slow growth process and rapid growth process results in hexagonal and whisker like morphologies. 相似文献
642.
Strongin DE Bevis B Khuong N Downing ME Strack RL Sundaram K Glick BS Keenan RJ 《Protein engineering, design & selection : PEDS》2007,20(11):525-534
The red fluorescent protein DsRed has been extensively engineered for use as an in vivo research tool. In fast maturing DsRed variants, the chromophore maturation half-time is approximately 40 min, compared to approximately 12 h for wild-type DsRed. Further, DsRed has been converted from a tetramer into a monomer, a task that entailed mutating approximately 20% of the amino acids. These engineered variants of DsRed have proven extremely valuable for biomedical research, but the structural basis for the improved characteristics has not been thoroughly investigated. Here we present a 1.7 A crystal structure of the fast maturing tetrameric variant DsRed.T4. We also present a biochemical characterization and 1.6 A crystal structure of the monomeric variant DsRed.M1, also known as DsRed-Monomer. Analysis of the crystal structures suggests that rearrangements of Ser69 and Glu215 contribute to fast maturation, and that positioning of the Lys70 side chain modulates fluorescence quantum yield. Despite the 45 mutations in DsRed.M1 relative to wild-type DsRed, there is a root-mean-square deviation of only 0.3 A between the two structures. We propose that novel intramolecular interactions in DsRed.M1 partially compensate for the loss of intermolecular interactions found in the tetramer. 相似文献
643.
Lanthanide orthoborates of composition LnBO3 (Ln = Tb, La, Pr, Nd, Sm, Eu, Gd, Dy, Y) and LaBO3:Gd, Tb, Eu have been prepared by metathesis reaction. This method provides a convenient route for the synthesis of orthoborates and its solid solutions at low temperatures. Powder X-ray diffraction and FT-IR spectroscopy were used to characterize these borates. Rare earth borates, (LnBO3) are isomorphous with different forms of CaCO3 depending on the radius of rare earth ion. LaBO3, LaBO3:Gd, Tb, Eu, PrBO3, NdBO3 crystallized in aragonite structure, SmBO3 crystallized in H-form and TbBO3, EuBO3, GdBO3, DyBO3, YBO3 crystallized in vaterite structure. The structural analysis of TbBO3 was carried out. The morphology of these borates was obtained from Scanning electron microscopy. Spin-Hamiltonian parameters for Gd3+ are deduced from room temperature electron spin resonance spectrum of LaBO3:Gd. The luminescence of LaBO3:Tb, Eu gave characteristics peaks corresponding to Tb3+, Eu3+ respectively. 相似文献
644.
Sundaram RS Steiner M Chiu HY Engel M Bol AA Krupke R Burghard M Kern K Avouris P 《Nano letters》2011,11(9):3833-3837
We combine optical microspectroscopy and electronic measurements to study how gold deposition affects the physical properties of graphene. We find that the electronic structure, the electron-phonon coupling, and the doping level in gold-plated graphene are largely preserved. The transfer lengths for electrons and holes at the graphene-gold contact have values as high as 1.6 μm. However, the interfacial coupling of graphene and gold causes local temperature drops of up to 500 K in operating electronic devices. 相似文献
645.
C. Vijayan M. Pandiaraman N. Soundararajan R. Chandramohan V. Dhanasekaran K. Sundaram T. Mahalingam A. John Peter 《Journal of Materials Science: Materials in Electronics》2011,22(5):545-550
Semiconducting Ag2SeTe thin films were prepared with different thicknesses onto glass substrates at room temperature using thermal evaporation technique. The structural properties were determined as a function of thickness by XRD exhibiting no preferential orientation along any plane, however the films are found to have peaks corresponding to mixed phase. The XRD studies were used to calculate the crystallite size and microstrain of the Ag2SeTe films. The calculated microstructure parameters reveal that the crystallite size increases and micro strain decreases with increasing film thickness. The refractive index, dielectric constants and thereby the optical bandgap of the films were calculated from transmittance spectral data recorded in the range 400?C1200 nm by UV?CVIS-Spectrometer. The direct optical bandgap of the Ag2SeTe thin films deposited on glass substrates with different thicknesses 50?C230 nm were found to be in the range 1.48?C1.59 eV. The carrier density value is estimated to be around 9.8 × 1021 cm?1 for the film thickness of 150 nm. The compositions estimated from the optical band gap studies reveal a value of 0.75 for Tellurium concentration. These structural and optical parameters are found to be very sensitive to the thin film thickness. 相似文献
646.
K. Sundaram M. Raja S. Thanikaikarasan J. P. Chu T. Mahalingam 《Materials Science-Poland》2011,29(3):165-170
The influence of pH and current density on the structural and magnetic behavior of soft magnetic Co-Ni-Fe alloy thin films has been studied. The effect of pH and current density on the compositional, structural, and magnetic properties of the as-obtained films was investigated by EDX (energy dispersive analysis by X-rays), XRD (X-ray diffractometer) and VSM (vibrating sample magnetometer). The EDX results revealed that at the optimized deposition conditions, nickel content was low compared with cobalt and ferrous content. X-ray diffraction patterns revealed that the deposited films have polycrystalline nature with mixed (fcc-bcc) cubic structure and small crystallite size (<20 nm). The films prepared in optimized conditions exhibit high saturation magnetization (4πMs value above 2T) and low coercivity (below 160 A/m), which may be due to the reduced crystallite size. 相似文献
647.
Chelsea Thompson M Motiur Rahman Soudamani Singh Subha Arthur Cecilia Sierra-Bakhshi Rebecca Russell Krista Denning Uma Sundaram Travis Salisbury 《International journal of molecular sciences》2021,22(13)
Obesity increases the risk of postmenopausal breast cancer (BC). This risk is mediated by obesity-induced changes in the adipose-derived secretome (ADS). The pathogenesis of BC in obesity is stimulated by mTOR hyperactivity. In obesity, leucine might support mTOR hyperactivity. Leucine uptake by BC cells is through L-Type Amino Acid Transporter 1 (LAT1). Our objective was to link obesity-ADS induction of LAT1 to the induction of mTOR signaling. Lean- and obese-ADS were obtained from lean and obese mice, respectively. Breast ADS was obtained from BC patients. Estrogen-receptor-positive BC cells were stimulated with ADS. LAT1 activity was determined by uptake of 3H-leucine. The LAT1/CD98 complex, and mTOR signaling were assayed by Western blot. The LAT1 antagonists, BCH and JPH203, were used to inhibit LAT1. Cell migration and invasion were measured by Transwell assays. The results showed obese-ADS-induced LAT1 activity by increasing transporter affinity for leucine. Consistent with this mechanism, LAT1 and CD98 expression were unchanged. Induction of mTOR by obese-ADS was inhibited by LAT1 antagonists. Breast ADS from patients with BMIs > 30 stimulated BC cell migration and invasiveness. Collectively, our findings show that obese-ADS induction of LAT1 supports mTOR hyperactivity in luminal BC cells. 相似文献
648.
Syed Muntazir Andrabi Jaya Tiwari Samarjeet Singh Joyita Sarkar Nishith Verma 《国际聚合物材料杂志》2016,65(12):636-645
A supermacroporous cryogel column of chitosan-dimethylaminoethyl methacrylate (DMAEMA)-magnetite has been synthesized. The cationic and magnetic properties of chitosan/DMAEMA and magnetite, respectively, allow the adhesion of metals and microbes to the matrix. The large interconnected pores (20–100 µm) with porosity greater than 85% of the cryogels facilitate fast water movement. At lab scale (approximately 2 mL bed volume), static binding capacity of 100% (load: 4.5 ppm arsenic and 2300 ppm chromium) and dynamic binding capacity of 65% for arsenic (load: 58 ppm) was observed. The binding capacity at pilot scale (approximately 300 mL bed volume) was found to be 11.5 mg arsenic and 14.22 mg chromium. There was 100% binding of microbes (Escherichia coli and Streptococci) both at lab and pilot scale. The results were propitious and indicated the suitability of cryogel filter as a single device for the removal of arsenic, chromium, and microbes in field samples. 相似文献
649.
650.
Graphene has attracted considerable interest over recent years due to its good electrical and mechanical properties. In the present study, a safe and facile method has been adopted for the preparation of reduced graphene oxide solution and its subsequent homogeneous dispersion into the poly(vinyl alcohol-g-acrylonitrile) film prepared by in situ free radical polymerization method. The prepared polymer-supported graphene films were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy techniques. 相似文献