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91.
Studies of double‐stranded‐DNA binding have been performed with three isomeric bis(2‐(n‐pyridyl)‐1H‐benzimidazole)s (n=2, 3, 4). Like the well‐known Hoechst 33258, which is a bisbenzimidazole compound, these three isomers bind to the minor groove of duplex DNA. DNA binding by the three isomers was investigated in the presence of the divalent metal ions Mg2+, Co2+, Ni2+, Cu2+, and Zn2+. Ligand–DNA interactions were probed with fluorescence and circular dichroism spectroscopy. These studies revealed that the binding of the 2‐pyridyl derivative to DNA is dramatically reduced in the presence of Co2+, Ni2+, and Cu2+ ions and is abolished completely at a ligand/metal‐cation ratio of 1:1. Control experiments done with the isomeric 3‐ and 4‐pyridyl derivatives showed that their binding to DNA is unaffected by the aforementioned transition‐metal ions. The ability of 2‐(2‐pyridyl)benzimidazole to chelate metal ions and the conformational changes of the ligand associated with ion chelation probably led to such unusual binding results for the ortho isomer. The addition of ethylenediaminetetraacetic acid (EDTA) reversed the effects completely. 相似文献
92.
Satish Mishra Rosa M. Badani Prado Song Zhang Thomas E. Lacy Xiaodan Gu Santanu Kundu 《Journal of Polymer Science.Polymer Physics》2019,57(15):1014-1026
Mechanical properties including the failure behavior of physically assembled gels or physical gels are governed by their network structure. To investigate such behavior, we consider a physical gel system consisting of poly(styrene)‐poly(isoprene)‐poly(styrene)[PS‐PI‐PS] in mineral oil. In these gels, the endblock (PS) molecular weights are not significantly different, whereas, the midblock (PI) molecular weight has been varied such that we can access gels with and without midblock entanglement. Small angle X‐ray scattering data reveals that the gels are composed of collapsed PS aggregates connected by PI chains. The gelation temperature has been found to be a function of the endblock concentration. Tensile tests display stretch‐rate dependent modulus at high strain for the gels with midblock entanglement. Creep failure behavior has also been found to be influenced by the entanglement. Fracture experiments with predefined cracks show that the energy release rate scales linearly with the crack‐tip velocity for all gels considered here. In addition, increase of midblock chain length resulted in higher viscous dissipation leading to a higher energy release rate. The results provide an insight into how midblock entanglement can possibly affect the mechanical properties of physically assembled triblock copolymer gels in a midblock selective solvent. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1014–1026 相似文献
93.
Nonlinear Dynamics - We obtain analytical approximations for period-1 rotations of both vertically and horizontally excited pendulum using Galerkin projections with elliptic functions (GP),... 相似文献
94.
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96.
Dr. M. Anne Sawhney Dr. Malik Wahid Dr. Santanu Muhkerjee Rebecca Griffin Prof. Alexander Roberts Prof. Satishchandra Ogale Dr. Jenny Baker 《Chemphyschem》2022,23(5):e202100860
Before the viability of a cell formulation can be assessed for implementation in commercial sodium ion batteries, processes applied in cell production should be validated and optimized. This review summarizes the steps performed in constructing sodium ion (Na-ion) cells at research scale, highlighting parameters and techniques that are likely to impact measured cycling performance. Consistent process-structure-performance links have been established for typical lithium-ion (Li-ion) cells, which can guide hypotheses to test in Na-ion cells. Liquid electrolyte viscosity, sequence of mixing electrode slurries, rate of drying electrodes and cycling characteristics of formation were found critical to the reported capacity of laboratory cells. Based on the observed importance of processing to battery performance outcomes, the current focus on novel materials in Na-ion research should be balanced with deeper investigation into mechanistic changes of cell components during and after production, to better inform future designs of these promising batteries. 相似文献
97.
Charge Transfer Induces Formation of Stimuli‐Responsive,Chiral, Cohesive Vesicles‐on‐a‐String that Eventually Turn into a Hydrogel
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A charge transfer (CT) mediated two‐component, multistimuli responsive supergelation involving a L ‐histidine‐appended pyrenyl derivative (PyHisOMe) as a donor and an asymmetric bolaamphiphilic naphthalene‐diimide (Asym‐NDI) derivative as an acceptor in a 2:1 mixture of H2O/MeOH was investigated. Asym‐NDI alone self‐assembled into pH‐responsive vesicular nanostructures in water. Excellent selectivity in CT gel formation was achieved in terms of choosing amino acid appended pyrenyl donor scaffolds. Circular dichroism and morphological studies suggested formation of chiral, interconnected vesicular assemblies resembling “pearls‐on‐a‐string” from these CT mixed stacks. XRD studies revealed the formation of monolayer lipid membranes from these CT mixed stacks that eventually led to the formation of individual vesicles. Strong cohesive forces among the interconnected vesicles originate from the protrusion of the oxyethylene chains from the surfaces of the chiral vesicles. 相似文献
98.
Propagation of SH‐wave in an initially stressed orthotropic medium sandwiched by a homogeneous and an inhomogeneous semi‐infinite media
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Santimoy Kundu Santanu Manna Shishir Gupta 《Mathematical Methods in the Applied Sciences》2015,38(9):1926-1936
The paper presents a study of propagation of shear wave (SH‐wave) in an orthotropic elastic medium under initial stress sandwiched by a homogeneous semi‐infinite medium and an inhomogeneous half‐space. The technique of separation of variables has been adopted to get the analytical solutions for the dispersion relation in a closed form. The propagation of SH‐waves is influenced by inhomogeneity parameters and initial stress parameter. Velocities of SH‐waves are calculated numerically for different cases. As a special case when the intermediate layer and half‐space are homogeneous, computed frequency equation coincides with general equation of Love wave. To study the effect of inhomogeneity parameters and initial stress parameter, we have plotted the velocity of SH‐wave in several figures and observed that the velocity of wave decreases with the increases of non‐dimensional wave number. It can be found that the phase velocity decreases with the increase of inhomogeneity parameters. We observed that the velocity of SH‐wave decreases with the increases of initial stress parameter in both homogeneous and inhomogeneous media. GUI has been developed by using MATLAB to generalize the effect of the parameters discussed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
99.
Kakali De Susmita Chandra Bhart Sarkar Santanu Ganguly Mridula Misra 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(3):621-628
In the recent years interests on dihydropyrimidinone and their analogues have increased potentially due to their wide range
of pharmacological/biological activities. Synthesis, radiolabeling with technetium-99 m (99mTc) and biological evaluation of 5-etoxycarbonyl-4-phenyl-6-methyl-3,4-dihydro-(1H)-pyrimidine-2-one (DHPM) were studied in
this present work. After synthesis complexation of DHPM with 99mTc was carried out using stannous chloride as the reducing agent. The complex (99mTc-DHPM) was characterized by thin layer chromatography, radio-HPLC technique and determination of partition co-efficient.
Radiochemical stability and particle size distribution of the complex were also measured. Biodistribution/scintigraphy studies
were performed in rats and rabbits to evaluate the pharmacological characteristics of this complex. The radiochemical purity
of the complex was over 95% as studied by thin layer chromatography and radio-HPLC. It was stable over 24 h at room temperature.
Its partition coefficient indicated that it was a lipophilic complex. According to the European Pharmacopeia, >80% of 99mTc labeled radiopharmaceutical (99mTc-MAA) in the size range 10–50 μm, must be accumulated in the lungs 15 min after intravenous administration. In this study
>85% of the 99mTc-DHPM complex in the average size of 40 μm. Biodistribution studies of 99mTc-DHPM in rat revealed that the complex accumulated in the lung with high uptake and good retention after intravenous administration.
Scintigraphic studies in rabbit also revealed that most of the administered radiolabeled complex was accumulated in the lungs
and after 1 h slowly excreted through the renal system. The lung uptake (ID%/g) was 10.12, 9.67, 8.60 and 5.01 and the lung/liver
ratio was 7.49, 2.88, 2.62 and 1.87 at 2, 15, 30 and 60 min post-injection, respectively. These results suggested that 99mTc-DHPM could be suitable as a potential lung perfusion imaging agent. Further studies with 99mTc-DHPM and its derivatives are warranted to develop new 99mTc-labeled imaging agents for clinical applications. 相似文献
100.
Santanu Deb‐Choudhury Jeffrey E. Plowman Ancy Thomas Gail L. Krsinic Jolon M. Dyer Stefan Clerens 《Electrophoresis》2010,31(17):2894-2902
Identification of the intermediate filament proteins (IFPs) in the wool proteome has formerly been hampered by limited sequence information, the high degree of IFP homology and their close proximity on 2‐DE maps. This has been partially rectified by the recent acquisition of four new Type I and two Type II wool IFP sequences. Among closely migrating proteins, such as IFP clusters in a 2‐DE map, proteins with higher sequence coverage will be assigned higher scores, but the identification of unique peptides in such tight clusters may distinguish these closely migrating proteins. Two approaches were adopted for the study of wool IFPs. In the first, searches were conducted for peptides known to be unique to each member of the family in each spot. In the second, MALDI imaging was employed to examine peptides bound to a PVDF membrane from a poorly resolved part of the Type I IFP region of the 2‐DE map. As a result, a distinct picture has emerged of the distribution of the six Type I and four Type II IFPs across the 2‐DE wool protein map. 相似文献