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91.
Mitra RN Dasgupta A Das D Roy S Debnath S Das PK 《Langmuir : the ACS journal of surfaces and colloids》2005,21(26):12115-12123
The primary objective of the present article is to understand how the geometric constraints at the surfactant head affect the lipase activity in the reverse micellar interface. To resolve this issue, surfactants were designed and synthesized, and activity was measured in /water/isooctane/n-hexanol reverse micellar systems at z ([alcohol]/[surfactant])=5.6, pH 6.0 (20 mM phosphate), 25 degrees C across a varying range of W0 ([water]/[surfactant]) using p-nitrophenylalkanoates as the substrate. It was observed that lipase activity increases from surfactants to with the increment in surface area per molecule (Amin) because of the substitution by the bulky tert-butyl group at the polar head. However, the activity was found to be similar for despite an enhancement in the hydrophilic moieties at the interface. This unchanged lipase activity is presumably due to the comparable surface area of to originating from the rigidity at the surfactant head. Noticeably, the enzyme activity improved from with the simultaneous increment of both the hydroxyl group and the flexibility of the headgroup whereas that for increased exclusively with the flexibility of the headgroup. The common parameter in both groups of surfactants and is the flexibility of the headgroup, which possibly enhance Amin and consequently the lipase activity. Thus, the geometric constraints at the surfactant headgroup play a crucial role in modulating the lipase activity profile probably because of the variation in interfacial area. 相似文献
92.
Bis(diisopropyl) thiophosphoryl disulfide (DIPDIS) being a rubber accelerator has a definite role as a coupling agent in the silica filled polychloroprene rubber with ethylene propylene diene rubber (CR‐EPDM) blends. Diethylene glycol can further improve the beneficial effect of DIPDIS in silica filled CR‐EPDM blends. Two‐stage vulcanization technique further improves the physical properties of silica filled CR‐EPDM blends. The results have been compared with non‐reinforcing calcium carbonate filled systems. Scanning electron microscopy (SEM) studies further indicate the coherency and homogeneity in the silica filled CR‐EPDM blend vulcanizates obtained from this two‐stage process. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
93.
§ 1.Introduction WearegivenkindependentWishartdensitiesofthe (p +q)× (p +q)randomsymmetricpositivedefinitematricesG1,… ,Gktobeg(Gi) =Kexp -12 trR- 1i Gi Gi12 (ni- q-p- 1) ,(1 )wherei=1 ,… ,k,andRidenotesthepopulationcorrelationmatrixofthei thpopulationandKasagenericletterdenote… 相似文献
94.
Some Kamenev-type oscillation criteria are obtained for a second order quasilinear damped differential equation with impulses. These criteria generalize and improve some well-known results for second order differential equations with /and without impulses. In addition, new oscillation criteria are also obtained to generalize and improve known results. Two examples of applications are given to illustrate the theory. 相似文献
95.
The behaviour ofS-matrix for potentials generating bound states in continuum in the neighbourhood of the positive bound state energies is studied.
It is shown that unlike the case of usual negative energy bound states, theS-matrix does not have a pole at the positive bound state energy but becomes unity at the energy corresponding to bound states
in continuum. Calculations ofS-waveS-matrix for a local potential constructed by Stillinger and Herrick and a separable nonlocal potential constructed by the
present authors verify these results. Our results indicate that the bound states embedded in continuum constructedvia the von Neumann and Wigner procedure cannot be interpreted as resonances with zero width. 相似文献
96.
Ujjal Debnath Subenoy Chakraborty John D. Barrow 《General Relativity and Gravitation》2004,36(2):231-243
We study the occurrence and nature of naked singularities for a dust model with non-zero cosmological constant in (n+2)-dimensional Szekeres space-times (which possess no Killing vectors) for n 2. We find that central shell-focusing singularities may be locally naked in higher dimensions but depend sensitively on the choice of initial data. In fact, the nature of the initial density determines the possibility of naked singularity in space-times with more than five dimensions. The results are similar to the collapse in spherically symmetric Tolman-Bondi-Lemaître space-times. 相似文献
97.
Raj Paul Dr. Debasish Dutta Dr. Tania Das Dr. Manish Debnath Prof. Dr. Jyotirmayee Dash 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(33):8590-8599
Specific sensing and functional tuning of nucleic acid secondary structures remain less explored to date. Herein, we report a thiazole polyamide TPW that binds specifically to c-KIT1 G-quadruplex (G4) with sub-micromolar affinity and ∼1 : 1 stoichiometry and represses c-KIT proto-oncogene expression. TPW shows up to 10-fold increase in fluorescence upon binding with c-KIT1 G4, but shows weak or no quantifiable binding to other G4s and ds26 DNA. TPW can increase the number of G4-specific antibody (BG4) foci and mark G4 structures in cancer cells. Cell-based assays reveal that TPW can efficiently repress c-KIT expression in leukemia cells via a G4-dependent process. Thus, the polyamide can serve as a promising probe for G-quadruplex recognition with the ability to specifically alter c-KIT oncogene expression. 相似文献
98.
Ganguly Soumya Gaonkar Raghuvir H. Sinha Samarendu Gupta Amit Chattopadhyay Dipankar Chattopadhyay Sankha Sachdeva Satbir S. Ganguly Shantanu Debnath Mita C. 《Journal of nanoparticle research》2016,18(7):1-21
Journal of Nanoparticle Research - This paper investigates the global nanotechnology and nanoscience (NN) indicators in a developmental context, during three 5-year periods from 2000 to 2014.... 相似文献
99.
100.
We have considered a cosmological model of the FRW universe with variable G and Λ. The solutions have been obtained for flat model with particular form of cosmological constant. The cosmological parameters
have also been obtained for dust, radiation and stiff matter. The statefinder parameters are analyzed and have shown that
these depends only on w and ε. Further the lookback time, proper distance, luminosity distance and angular diameter distance have also been calculated
for our model. 相似文献