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1.
Bhamidi V Varanasi S Schall CA 《Langmuir : the ACS journal of surfaces and colloids》2005,21(20):9044-9050
Fundamental understanding of protein crystal nucleation facilitates crystallization of biological macromolecules for structure determination and control of crystal size distribution. In the studies presented here, nucleation kinetics of hen egg-white lysozyme crystals were measured at solution conditions that exhibited equal solubility by adjusting pH, temperature, or sodium chloride concentration. It was observed that solution conditions that lead to equal solubility resulted in equal nucleation rates and hence kinetic parameters. Since the solubility of globular proteins correlates with the osmotic second virial coefficient, B(22), an integral measure of the protein pair interaction potential, this observation indicates that the protein pair interaction plays a key role in determining nucleation kinetic parameters. 相似文献
2.
Magnetic nanoparticle‐tethered Schiff base–palladium(II): Highly active and reusable heterogeneous catalyst for Suzuki–Miyaura cross‐coupling and reduction of nitroarenes in aqueous medium at room temperature 下载免费PDF全文
K. Manjunatha Tuhin S. Koley Vishal Kandathil Ramesh B. Dateer Geetha Balakrishna B. S. Sasidhar Shivaputra A. Patil Siddappa A. Patil 《应用有机金属化学》2018,32(4)
As a continuation of our efforts to develop new heterogeneous nanomagnetic catalysts for greener reactions, we identified a Schiff base–palladium(II) complex anchored on magnetic nanoparticles (SB‐Pd@MNPs) as a highly active nanomagnetic catalyst for Suzuki–Miyaura cross‐coupling reactions between phenylboronic acid and aryl halides and for the reduction of nitroarenes using sodium borohydride in an aqueous medium at room temperature. The SB‐Pd@MNPs nanomagnetic catalyst shows notable advantages such as simplicity of operation, excellent yields, short reaction times, heterogeneous nature, easy magnetic work up and recyclability. Characterization of the synthesized SB‐Pd@MNPs nanomagnetic catalyst was performed with various physicochemical methods such as attenuated total reflectance infrared spectroscopy, UV–visible spectroscopy, inductively coupled plasma atomic emission spectroscopy, energy‐dispersive X‐ray spectroscopy, field‐emission scanning electron microscopy, transmission electron microscopy, powder X‐ray powder diffraction, thermogravimetric analysis and Brunauer–Emmett–Teller surface area analysis. 相似文献
3.
Cellulose nanofibre aspect ratio controls the properties of sheets made from nanofibres and processing conditions, but aspect ratio is very difficult to measure. In this paper, aspect ratio was estimated from the gel point of a cellulose nanofibre suspension, the solids concentration at which the transition from a dilute to a semi-dilute suspension occurs. Four batches of cellulose nanofibres were tested. Two were produced from softwood fibres using ball milling. Commercially produced microfibrillated cellulose material was also used, both in as supplied form and after removal of the larger fibres by filtering. The average diameter measured from SEM images of fibres ranged from 33 to 73 nm. One sample was too heavily treated and an average dimension could not be measured. The gel-point was measured both from the height of a layer of cellulose nanofibres sedimented from a dilute suspension or from the lowest solids concentration at which a yield stress could be measured using a vane rheometer. The two methods were closely in agreement for all samples. Aspect ratio was then calculated using either the effective medium (EMT) or crowding number (CN) theories. Aspect ratio calculated with an assumed fibre density of 1,500 kg/m3, using the CN theory ranged from 155 to 60. Use of the EMT theory reduced the calculated aspect ratio by between 11 and 23 %. Reducing the assumed density in suspension from 1,500 to 1,166 kg/m3 reduced the calculated aspect ratio by 12–14 %. The heavily treated sample had by far the lowest aspect ratio. 相似文献
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5.
Pei Li Qichao Zhao Jared L. Anderson Sasidhar Varanasi Maria R. Coleman 《Journal of polymer science. Part A, Polymer chemistry》2010,48(18):4036-4046
Block copolyimides based on aromatic dianhydrides and diamines copolymerized with diamino room temperature ionic liquid (RTIL) monomers were synthesized over a range of compositions. Specifically, two diamino RTILs, 1,3‐di(3‐aminopropyl) imidazolium bis[(trifluoromethyl)sulfonyl] imide ([DAPIM] [NTf2]) and 1,12‐di[3‐(3‐aminopropyl) imidazolium] dodecane bis[(trifluoromethyl) sulfonyl] imide ([C12 (DAPIM)2] [NTf2]2) were synthesized using a Boc protection method. The two RTILs were reacted with 2,2‐bis(3,4‐carboxylphenyl) hexafluoropropane dianhydride (6FDA) to produce 6FDA‐RTILs oligomers that formed the RTIL component for the block copolyimides. The oligomers were reacted with 6FDA and m‐phenylenediamine (MDA) at oligomer concentration from 6.5 to 25.8 mol % to form block copolyimides. Increasing the concentration of the 6FDA‐RTIL oligomer in the block copolyimides resulted in a decrease in the thermal degradation temperature, glass transition temperature and an increase in the density. The gas permeability of the RTIL based block copolyimide decreased but the ideal permeability selectivity for CO2/CH4 gas pair increased relative to the pure 6FDA‐MDA. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4036–4046, 2010 相似文献
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7.
Prasad Varanasi Larry A. Pugh Babu R.P. Bangaru 《Journal of Quantitative Spectroscopy & Radiative Transfer》1974,14(9):829-838
Integrated intensity data at 300°K for J-multiplets between P(11)and R(11) in the V3-fundamental of 12CH4 are presented, along with the intensity of the entire Q-branch, which also encompasses the Q-branch of the V3-fundamental of 13CH4. These data, together with theoretical estimates for the intensities of J-multiplets of J > 11, sum up to a value of Sband= 284±14cm?2atm?1 at 300°K. This results is in excellent agreement with most of the previously published values for this parameter. Within experimental error, the intensities of the J-multiplets in the V3-fundamental do not seem to exhibit the strong anamolies that were characteristic of lines in the 2V3-band.Line widths have been measured at 100°K, 130°K, 190°K, 250°K, and 300°K for R(0), R(1), and R(2) broadened by He, Ne and Ar. The temperature dependence of the line width is discussed for the three cases of broadening. In neon broadening at 300°K, the ‘effective mean line widths’ for multiplets R(3) through R(11) have also been obtained experimentally; their J-dependence is interpreted using Gordon's theory of line shapes in multiplet spectra. 相似文献
8.
P. Varanasi 《Journal of Quantitative Spectroscopy & Radiative Transfer》1983,30(6):517-522
Spectral transmittance measurements have been performed in the v6-fundamental of 12CH3D at 153 K. Relevant to the studies of the emission spectra of Titan recorded by the IRIS instruments on board Voyagers 1 and 2, N2 has been used as the broadening gas. Excellent agreement between experimental and theoretical spectral transmittance has been the result of using N2-broadened line widths and their dependence upon temperature measured by us in the v2-fundamental and S = 63.6 cm-2 atm-1 for the absolute intensity of the v6-fundamental. 相似文献
9.
Sasidhar Chavali Philip M. Birch Rupert Young Chris Chatwin 《Optics and Lasers in Engineering》2007,45(3):413
Achieving phase only modulation from a spatial light modulator (SLM) is useful for many optical processing tasks. In this paper, we demonstrate a simple method of decoupling phase and amplitude modulation in a twisted nematic liquid crystal (TNLC) SLM using a double pass technique. A Jones calculus model is developed which matches our experimental data. 相似文献
10.
The optical microscopic mass transport (OMMT) method was utilized to determine the cholesteric pitch values of the mixtures of mesogenic and non-mesogenic chiral species in nematic materials. The cholesteric pitch was determined by transient analysis of the diffusion profile established by allowing an initial cholestric composition (solute) to diffuse under semi-infinite linear boundary conditions into an oriented thin film of its corresponding nematic solvent. During the steady-state diffusion, where the initial concentration (pitch) remains constant, the transient analysis of the profile with a polarization microscope exhibits a maximum number of pitch discontinuity domains. The evaluation of the unknown pitch was carried out by extrapolation of the diffusion pitch gradient to the original diffusion source by using the exact relation between the pitch and the film thickness. The method is experimentally simple; at constant temperature and pressure, determination of the pitch depends only on the film thickness. There is a good agreement between the pitch values obtained with this method and those from conventional techniques. 相似文献