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61.
R. Parimaladevi C. Sekar V. Krishnakumar 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,74(1):248-252
Single crystals of ferroelectric material triglycine sulpho phosphate (TGSP) have been grown by slow evaporation method. The effect of l-lysine addition on the growth of TGSP crystal has been studied for various concentrations (5, 10 and 20 mol%). Unit cell parameters were determined from powder XRD analysis. Functional groups present in the grown crystal were confirmed from the vibrational frequencies of recorded FTIR and FT-Raman spectrum. The l-lysine doping into the crystal lattice has been qualitatively confirmed by spectral analysis. Thermogravimetric studies confirm that the lysine is incorporated into TGSP crystals. Dielectric studies reveal that the incorporation of lysine into TGSP enhances its dielectric strength. 相似文献
62.
Kathiravan A Chandramohan M Renganathan R Sekar S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,71(5):1783-1787
Chlorophyll has been extracted from cyanobacteria. The adsorption of chlorophyll on the surface of colloidal TiO(2) through electrostatic interaction was observed. The apparent association constant (K(app)) of chlorophyll-TiO(2) obtained from absorption spectra is 3.78x10(4)M(-1). The K(app) value of chlorophyll-TiO(2) as determined from fluorescence spectra is 1.81x10(4)M(-1), which matches well with that determined from the absorption spectra changes. These data indicate that there is an interaction between chlorophyll and colloidal TiO(2) nanoparticle surface. The dynamics of photoinduced electron transfer from chlorophyll to the conduction band of colloidal TiO(2) nanoparticle has been observed and the mechanism of electron transfer has been confirmed by the calculation of free energy change (DeltaG(et)) by applying Rehm-Weller equation as well as energy level diagram. Lifetime measurements gave the rate constant (k(et)) for electron injection from the excited state chlorophyll into the conduction band of TiO(2) is 4.2x10(8)s(-1). 相似文献
63.
Smrithi Krishnan R. Neethu Puthumadathil Amina H. Shaji K. Santhosh Kumar Gayathri Mohan Kozhinjampara R. Mahendran 《Chemical science》2021,12(2):639
Synthetic alpha-helix based pores for selective sensing of peptides have not been characterized previously. Here, we report large transmembrane pores, pPorA formed from short synthetic alpha-helical peptides of tunable conductance and selectivity for single-molecule sensing of peptides. We quantified the selective translocation kinetics of differently charged cationic and anionic peptides through these synthetic pores at single-molecule resolution. The charged peptides are electrophoretically pulled into the pores resulting in an increase in the dissociation rate with the voltage indicating successful translocation of peptides. More specifically, we elucidated the charge pattern lining the pore lumen and the orientation of the pores in the membrane based on the asymmetry in the peptide-binding kinetics. The salt and pH-dependent measurements confirm the electrostatic dominance and charge selectivity in controlling target peptide interaction with the pores. Remarkably, we tuned the selectivity of the pores to charged peptides by modifying the charge composition of the pores, thus establishing the molecular and electrostatic basis of peptide translocation. We suggest that these synthetic pores that selectively conduct specific ions and biomolecules are advantageous for nanopore proteomics analysis and synthetic nanobiotechnology applications.Synthetic alpha-helix based pores for selective sensing of peptides have not been characterized previously. 相似文献
64.
The influence of Zn-doping on the crystal structure and magnetic properties of the spin ladder compounds La2Cu2O5 (4-leg) and La8Cu7O19 (5-leg) have been investigated. The La2(Cu1−xZnx)2O5 and La8(Cu1−xZnx)7O19 solid solutions were obtained as single phases with x=0-0.1 via the solid-state reaction method in the temperature range between 1005-1010 °C and 1015-1030 °C in oxygen and air atmospheres, respectively. The lattice parameters a and c of the monoclinic crystal structures as well as the unit cell volume V increase with increasing x, while b and β decrease for both series. The magnetic susceptibilities χ of both series show a very similar behavior on temperature as well as on Zn-doping, which is supposed to be due to the similar Cu-O coordination in both La2Cu2O5 and La8Cu7O19. For low Zn-doping (x?0.04), a spin-chain like behavior is found. This quasi-one-dimensional behavior is strongly suppressed in both series for x?0.04. Here, the maximum (characteristic for spin chains) in χ(T) disappears and χ(T) decreases monotonically with increasing temperature. 相似文献
65.
Crystal Structure Investigations and Thermal Behavior of the Five‐Leg Spin Ladder Compound La8Cu7O19
Barbara Schüpp Chinnathambi Sekar Wolfgang Gruner Gudrun Auffermann Carsten Bhtz Gernot Krabbes 《无机化学与普通化学杂志》2004,630(5):663-668
La8Cu7O19 was synthesized by solid state reaction of the oxides La2O3 and CuO at 1288 K in air. The crystal structure was determined by a joint Rietveld refinement of X‐ray and neutron powder diffraction data. La8Cu7O19 crystallizes in the monoclinic space group C2/c (No. 15) with the lattice parameters a = 13.8310(4)Å, b = 3.75827(9)Å, c = 34.5917(8)Å and β = 99.332(2)°. La8Cu7O19 is the n = 3 member of the homologous series La4+4nCu8+2nO14+8n. The Cu—O sub‐structure in La8Cu7O19 contains infinite ribbons, which can be described as perovskite type layers with a width of n = 3 Jahn‐Teller‐elongated octahedra, and Cu—O planes of complex geometry. DSC/TG‐measurements in different gas atmospheres show peritectic decomposition of La8Cu7O19. The anisotropic thermal expansion of the lattice parameters was investigated using synchrotron radiation. The Madelung part of lattice energy was calculated and compared with the corresponding values of other lanthanum cuprates. 相似文献
66.
Several mixed Te/Se polychalcogenide anions [Te(m)Se(n)](2-) were synthesized at 293 K by reactions between Te(n)(2-)and Se(n)(2-) anions in N,N-dimethylformamide (DMF) in the presence of different-size ammonium or phosphonium cations, in some cases in the presence of metal species. The structures of these anions were determined by single-crystal X-ray diffraction methods. The crystal structures of [NEt(4)](2)[Te(3)Se(6)] (1) and [NEt(4)](2)[Te(3)Se(7)] (2) consist, respectively, of one-dimensional infinite 1(infinity)[Te(3)Se(6)(2-)] and 1(infinity)[Te(3)Se(7)(2-)] anionic chains separated by NEt(4)(+) cations. In compound 1, each chain comprises Te(3)Se(5) eight-membered rings bridged by Se atoms. The Te(3)Se(5) ring has an "open book" conformation. The NMR spectrum of a DMF solution of [NEt(4)](2)[Te(3)Se(6)] crystals at 223 K shows (77)Se resonances at delta = 290, 349, and 771 ppm and a single (125)Te resonance at delta = 944.7 ppm. In compound 2, each chain comprises Te(3)Se(6) five- and six-membered rings bridged by Se atoms. The Te(3)Se(6) ring can be regarded as an inorganic analogue of bicyclononane. The anion of [PPh(4)](2)[Te(2)Se(2)] (4) contains a Se-Te-Te-Se chain with the terminal Se atoms trans to one another. The new compounds [PPN](2)[TeSe(10)] (3), [NMe(4)](2)[TeSe(3)].DMF (5), and [NEt(4)](2)[TeSe(3)] (6) contain known anions. 相似文献
67.
Farrah Syazana Khattulanuar Mahendran Sekar Shivkanya Fuloria Siew Hua Gan Nur Najihah Izzati Mat Rani Subban Ravi Kumarappan Chidambaram M. Yasmin Begum Abul Kalam Azad Srikanth Jeyabalan Arulmozhi Dhiravidamani Lakshmi Thangavelu Pei Teng Lum Vetriselvan Subramaniyan Yuan Seng Wu Kathiresan V. Sathasivam Neeraj Kumar Fuloria 《Molecules (Basel, Switzerland)》2022,27(3)
Cardiovascular disorders (CVDs) are the leading risk factor for death worldwide, and research into the processes and treatment regimens has received a lot of attention. Tilianin is a flavonoid glycoside that can be found in a wide range of medicinal plants and is most commonly obtained from Dracocephalum moldavica. Due to its extensive range of biological actions, it has become a well-known molecule in recent years. In particular, numerous studies have shown that tilianin has cardioprotective properties against CVDs. Hence, this review summarises tilianin’s preclinical research in CVDs, as well as its mechanism of action and opportunities in future drug development. The physicochemical and drug-likeness properties, as well as the toxicity profile, were also highlighted. Tilianin can be a natural lead molecule in the therapy of CVDs such as coronary heart disease, angina pectoris, hypertension, and myocardial ischemia, according to scientific evidence. Free radical scavenging, inflammation control, mitochondrial function regulation, and related signalling pathways are all thought to play a role in tilianin’s cardioprotective actions. Finally, we discuss tilianin-derived compounds, as well as the limitations and opportunities of using tilianin as a lead molecule in drug development for CVDs. Overall, the scientific evidence presented in this review supports that tilianin and its derivatives could be used as a lead molecule in CVD drug development initiatives. 相似文献
68.
Acta Mechanica Sinica - To improve the performance of multilayer perceptron (MLP) neural networks activated by conventional activation functions, this paper presents a new MLP activated by... 相似文献
69.
M. Yogavel P. G. Aravindan D. Velmurugan K. Sekar S. Selvi P. T. Perumal S. Shanmuga Sundara Raj H.‐K. Fun 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(7):o394-o396
In the title compounds, C13H15N3O, (I), and C13H15N3O2, (II), the dihedral angles between the planes of the phenyl ring and the amide group are 4.1 (1) and 20.7 (1)°, respectively. The molecules adopt a fully extended conformation, aided by intramolecular interactions. The molecular structures of (I) and (II) display different crystal packing and hydrogen‐bonding networks. 相似文献
70.
R.S. Mahendran L. Wang V.R. Machavaram S.D. Pandita R. Chen S.N. Kukureka G.F. Fernando 《Optics and Lasers in Engineering》2009,47(10):1069-1076
“Curing” is a term that is used to describe the cross-linking reactions in a thermosetting resin system. Advanced fiber-reinforced composites are being used increasingly in a number of industrial sectors including aerospace, marine, sport, automotive and civil engineering. There is a general realization that the processing conditions that are used to manufacture the composite can have a major influence on its hot–wet mechanical properties. This paper is concerned with the design and demonstration of a number of sensor designs for in situ monitoring of the cross-linking reactions of a commercially available thermosetting resin system. Simple fixtures were constructed to enable a pair of cleaved optical fibers with a defined gap between the end-faces to be held in position. The resin system was introduced into this gap and the cure kinetics were followed by transmission infrared spectroscopy. A semi-empirical model was used to describe the cure process using the data obtained at different cure temperatures. The same sensor system was used to detect the ingress of moisture into the cured resin system. 相似文献