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排序方式: 共有71条查询结果,搜索用时 31 毫秒
1.
Recognition of the stereochemical features inherent to a nucleotide, viz., the preferred trans character of the two C? O bonds and the approximate chemical and conformational symmetry, has facilitated the representation of a nucleotide in terms of two nearly equal blocks or two virtual bonds spanning the atoms P to C4' on the 5' side and C4' to P on the 3' side. The scheme, by virtue of its unique ability to account for the main sources of flexibility and to incorporate their interdependence, could be effectively applied to probe ordered, as well as random coil conformations of polynucleotide chains. Using this scheme, conformations of nucleotide, dinucleotides, helices, and yeast tRNAPhe have been characterized by virtual bond parameters. The two blocks of nucleotide have also been described in terms of two approximate planes similar to peptides. Unperturbed end-to-end dimensions and persistence lengths of random coil polynucleotides have been computed by considering short-range as well as near-neighbor bond long-range correlations and are in excellent agreement with the experimentally determined values. A striking finding of these studies is the relevation that random coils comprise of a large proportion of stacked A-type helical segments in sharp contrast to earlier interpretations which invoked a high fraction of unstacked extended conformations. 相似文献
2.
A highly sensitive extractive spectrophotometric method for the determination of U(VI) using octadecyldithiocarbamate (ODDTC) has been developed. The efficiency of ODDTC as a chelating agent is compared with that of hexadecyl, tetradecyl and dodecyl dithiocarbamates. U(VI) reacts with these dithiocarbamates in ethanol to form reddish-brown water-insoluble chelates capable of being extracted into CHCl3. The molar absorptivities range from 1.16·10 to 4.91·104l·mol–1·cm–1, the highest value being found for ODDTC. Suitable conditions for the extraction and the effect of foreign ions were investigated. The method can be used for the determination of trace amounts of U(VI) in water and sand. The results are comparable to ICP-AES method. 相似文献
3.
Kiruthika S. Malathi M. Selvasekarapandian S. Tamilarasan K. Moniha V. Manjuladevi R. 《Journal of Solid State Electrochemistry》2019,23(7):2181-2193
Journal of Solid State Electrochemistry - Current research on electrochemical device application focuses on the usage of biopolymers like chitosan, pectin, agar-agar, cellulose acetate, and... 相似文献
4.
Ramesh Sundar Amalraj Nagarathinam Selvaraj Ganesh Kumar Veluswamy Rahul Pathirickal Ramanujan Raveendran Muthurajan Malathi Palaniyandi Ganesh Kumar Agrawal Randeep Rakwal Rasappa Viswanathan 《Electrophoresis》2010,31(12):1959-1974
Sugarcane is an important commercial crop cultivated for its stalks and sugar is a prized commodity essential in human nutrition. Proteomics of sugarcane is in its infancy, especially when dealing with the stalk tissues, where there is no study to date. A systematic proteome analysis of stalk tissue yet remains to be investigated in sugarcane, wherein the stalk tissue is well known for its rigidity, fibrous nature, and the presence of oxidative enzymes, phenolic compounds and extreme levels of carbohydrates, thus making the protein extraction complicated. Here, we evaluated five different protein extraction methods in sugarcane stalk tissues. These methods are as follows: direct extraction using lysis buffer (LB), TCA/acetone precipitation followed by solubilization in LB, LB containing thiourea (LBT), and LBT containing tris, and phenol extraction. Both quantitative and qualitative protein analyses were performed for each method. 2‐DE analysis of extracted total proteins revealed distinct differences in protein patterns among the methods, which might be due to their physicochemical limitations. Based on the 2‐D gel protein profiles, TCA/acetone precipitation‐LBT and phenol extraction methods showed good results. The phenol method showed a shift in pI values of proteins on 2‐D gel, which was mostly overcome by the use of 2‐D cleanup kit after protein extraction. Among all the methods tested, 2‐D cleanup‐phenol method was found to be the most suitable for producing high number of good‐quality spots and reproducibility. In total, 30 and 12 protein spots commonly present in LB, LBT and phenol methods, and LBT method were selected and subjected to eLD‐IT‐TOF‐MS/MS and nESI‐LC‐MS/MS analyses, respectively, and a reference map has been established for sugarcane stalk tissue proteome. A total of 36 nonredundant proteins were identified. This is a very first basic study on sugarcane stalk proteome analysis and will promote the unexplored areas of sugarcane proteome research. 相似文献
5.
The development of polymeric systems with high ionic conductivity is one of the main objectives in Li rechargeable battery. In the present study, the different composition of PVA-LiCF3SO3 polymer electrolyte has been prepared by solution cast technique using DMSO as solvent. The FTIR study confirms the polymer-salt complex formation. The amorphous nature of the polymer has been confirmed by XRD analysis. DSC measurements show decrease in Tg with increasing salt concentration. The temperature dependent conductivity obeys Arrhenius relationship. The maximum conductivity has been observed in the order of 7 × 10− 4 S cm− 1 for 25 mol% of LiCF3SO3. The activation energy has been found to be 0.16 eV. The two peaks have been observed in the dielectric loss spectrum which shows two types of relaxation α and β. 相似文献
6.
Indhumathi Kulandhaisamy Dinesh Babu Rajendran Malathi Kanagasabai Gunasekaran Gurusamy Balaji Moorthy Jithila V. George 《Waves in Random and Complex Media》2017,27(1):38-46
In this paper, an analog multiband phase shifter using slotline configuration is proposed. To implement the design, a pair of modified Split Ring Resonator (SRR) is employed. The periodic property of SRR provides multiband characteristics, whether the coupling slot gives the phase variations over the bands. The operation is well explained with an equivalent circuit model and its characteristics have been studied both in simulation and measurement. The prototype operates in 1.77–2.16, 3.5–3.97, 5.08–5.33, 6.43–6.93, and 8.01–8.59 GHz frequency bands which can be utilized for GSM, GPS, WLAN, C-band, and X-band applications, respectively. 相似文献
7.
Yoboué A Susset A Tougerti A Gallego D Ramani SV Kalyanikar M Dolzhnikov DS Wubshet SG Wang Y Cristol S Briois V La Fontaine C Gauvin RM Paul JF Berrier E 《Chemical communications (Cambridge, England)》2011,47(14):4285-4287
Heterogeneous Re/SiO(2) catalysts prepared using a one pot sol-gel synthesis were found to display high activity in the direct, selective methanol conversion to methylal, which is correlated to an unprecedented rhenium oxide structure. 相似文献
8.
Gopalakrishnan R Balamurugan K Singam ER Sundaraman S Subramanian V 《Physical chemistry chemical physics : PCCP》2011,13(28):13046-13057
Classical molecular dynamics (MD) simulation has been carried out to understand the adsorption of collagen like peptides onto single walled carbon nanotubes (CNT) in an aqueous environment. It is observed that the triple helical structure of all the model collagen like peptides (CPs) has been unaltered upon adsorption onto CNT. The model CPs do not wrap around the CNT, however, the axis of the triple helix subtends a cross angle with respect to the axis of the CNT. The interaction between the CPs and CNT as well as that between the CPs and water molecules was observed by MD simulation snapshots. The inherent nature of the interaction of CPs with CNT facilitates the penetration of CPs into the water/CNT interface. During this process, water molecules trapped between the CPs and CNT are appreciably displaced. Although, hydrophobic-hydrophobic interaction is crucial for the interaction, the role of πR (R = OH and NH(2)) interactions are also observed from the geometrical parameters. The sequence specific interaction of CPs with CNT is evident from the results. It is found that the length of the CNT, curvature of the CNT and length of the CPs do not significantly influence interaction between the two systems. Overall the findings provide important information for the development of nanocomposite materials from collagen and CNT. 相似文献
9.
Hongqiang Lu Malathi Thothathiri Ziming Wu Ishawara Bhat 《Journal of Electronic Materials》1997,26(3):281-284
Indium droplet formation during the epitaxial growth of InxGa1−xN films is a serious problem for achieving high quality films with high indium mole fraction. In this paper, we studied the
formation of indium droplets on the InxGa1−xN films grown by metalorganic chemical vapor deposition (MOCVD) using single crystal x-ray diffraction. It is found that the
indium (101) peak in the x-ray diffraction spectra can be utilized as a quantitative measure to determine the amounts of indium
droplets on the film. It is shown by monitoring the indium diffraction peak that the density of indium droplets increases
at lower growth temperature. To suppress these indium droplets, a modulation growth technique is used. Indium droplet formation
in the modulation growth is investigated and it is revealed in our study that the indium droplets problem has been partially
relieved by the modulation growth technique. 相似文献
10.
Dommety Gopal Veeraraghavan Malathi Singhal Mukesh 《Mobile Networks and Applications》1998,3(2):203-220
This paper presents an algorithm for optimizing the route of a connection that becomes suboptimal due to operations such as
handoffs and location-based reroutes, and applies this algorithm to the handoff management problem in mobile ATM (Asynchronous
Transfer Mode) networks based on the PNNI (Private Network-to-Network Interface) standard. The route optimization algorithm
uses hierarchical route information of the connection and summarized topology and loading information of the network to determine
a “crossover node” such that adjusting the connection from that crossover node results in an optimally routed connection.
Handoff management schemes that perform local rerouting of connections have been proposed in order to support fast handoffs.
These methods result in suboptimally routed connections. In this paper, we demonstrate how this route optimization algorithm
can be used to optimize the route of a connection after such a handoff is executed, as the second phase of a two-phase handoff scheme. This route optimization procedure can also be executed as part of the handoff procedure resulting in a one-phase handoff scheme. Applying this route optimization algorithm, we propose two one-phase schemes, the one-phase optimal scheme and the one-phase
minimal scheme. A comparative performance analysis of one- and two-phase handoff schemes is presented. Measures of comparison
are handoff latency and the amount of network resources used by a connection. Handoff latency in the one-phase optimal scheme is greater than that in the two-phase schemes, and
handoff latency in the one-phase minimal scheme is smaller than that in the two-phase schemes. The one-phase methods show
a significant increase in efficiency of the connection compared to the two-phase methods.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献