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31.
Yasmine S. Zubi Bingqing Liu Yifan Gu Dipankar Sahoo Jared C. Lewis 《Chemical science》2022,13(5):1459
Visible light photocatalysis enables a broad range of organic transformations that proceed via single electron or energy transfer. Metal polypyridyl complexes are among the most commonly employed visible light photocatalysts. The photophysical properties of these complexes have been extensively studied and can be tuned by modifying the substituents on the pyridine ligands. On the other hand, ligand modifications that enable substrate binding to control reaction selectivity remain rare. Given the exquisite control that enzymes exert over electron and energy transfer processes in nature, we envisioned that artificial metalloenzymes (ArMs) created by incorporating Ru(ii) polypyridyl complexes into a suitable protein scaffold could provide a means to control photocatalyst properties. This study describes approaches to create covalent and non-covalent ArMs from a variety of Ru(ii) polypyridyl cofactors and a prolyl oligopeptidase scaffold. A panel of ArMs with enhanced photophysical properties were engineered, and the nature of the scaffold/cofactor interactions in these systems was investigated. These ArMs provided higher yields and rates than Ru(Bpy)32+ for the reductive cyclization of dienones and the [2 + 2] photocycloaddition between C-cinnamoyl imidazole and 4-methoxystyrene, suggesting that protein scaffolds could provide a means to improve the efficiency of visible light photocatalysts.Artificial metalloenzyme visible light photocatalysts possess enhanced optical properties and are competent towards single electron and energy transfer organic transformations. 相似文献
32.
In this article, the analysis of Tsallis holographic dark energy(which turns into holographic dark energy for a particular choice of positive non-additivity parameter δ) in modified f(T, B) gravity with the validity of thermodynamics and energy conditions for a homogeneous and isotropic FLRW Universe has been studied. The enlightenment of the field equation towards f(T,B)=αT~m+βB~n, made possible by the fact that the model is purely accelerating,corresponds to q=-0.54(Mamon and Das 2017 Eur. Phys.J.C 77 49). The generalized second law of thermodynamics is valid not only for the same temperature inside the horizon, but also for the apparent horizon for a change in temperature. The essential inspiration driving this article is to exhibit the applicability that the holographic dark energy achieved from standard Tsallis holographic dark energy and the components acquired from f(T, B) gravity are identical for the specific bounty of constants. The analysis of energy conditions confirms that the weak energy condition and the null energy condition are fulfilled throughout the expansion, while violation of the strong energy condition validates the accelerated expansion of the Universe.With the expansion, the model becomes a quintessence dominated model. The dominant energy condition is not observed initially when the model is filled with genuine baryonic matter,whereas it appears when the model is in the quintessence dominated era. 相似文献
33.
Jeong Junho Briere Tina M. Sahoo N. Das T. P. Ohira Seiko Nishiyama K. Nagamine K. 《Hyperfine Interactions》2001,136(3-8):769-775
The trapping sites for muon and muonium in ferromagnetic p-Cl–Ph–CH=N–TEMPO [(4-(p-chlorobenzylideneamino)–TEMPO (TEMPO = 2,6,6-tetramethyl-piperidin-1-yloxyl)]
and the hyperfine interaction tensors for these sites are obtained using first-principles Unrestricted Hartree–Fock theory.
The calculated hyperfine interactions are used to compare the calculated zero field muon spin rotation (μSR) frequencies for
different choices for the easy axis and the observed frequency. It has been concluded that the two trapping centers that can
best explain the observed μSR frequency are a trapped singlet muonium near the radical oxygen and a trapped muon site near
the chlorine. The direction of the easy axis also is determined to be the b-axis of the monoclinic lattice. This direction for the easy axis is confirmed by determining the direction of the distributed
magnetization in the molecular solid which leads to a minimum dipole–dipole interaction energy. The consequences of this agreement
for the easy axis direction by two independent procedures are discussed.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
34.
The electric field gradients at27Al and63Cu nuclei which are nearest neighbors to the muon in the face-centered cubic metals aluminum and copper, with muon at an octahedral
interstitial site, are studied. The electron density fluctuations needed for the evaluation of the electronic, or valence,
contributions to field gradients are taken from earlier investigations involving the spherical solid approximation. The enhancement
factors a that have to be applied to the electric field-gradients obtained from these approximations, due to the departures
of the electronic wave-functions from plane-wave character, and the incorporation of antishielding effects, have been obtained
for both APW and OPW approaches to the conduction electron wave-functions and good agreement is found between the results
by the two approaches. Size effects due to the lattice distortion associated with the presence of the muon are included through
actual point ion summations using available calculated displacements of the ions surrounding the muon. The valence contributions
are the dominant ones but the size effect contributions are also significant. The net field-gradient obtained for the27Al site is significantly smaller than experiment while that for63Cu is substantially larger than experiment. Possible sources that could lead to better agreement with experiment are discussed
and it is concluded that major improvement is needed in the valence effect contributions in both metals. 相似文献
35.
A new method for exact solutions of variant types of time‐fractional Korteweg‐de Vries equations in shallow water waves 下载免费PDF全文
The current article devoted on the new method for finding the exact solutions of some time‐fractional Korteweg–de Vries (KdV) type equations appearing in shallow water waves. We employ the new method here for time‐fractional equations viz. time‐fractional KdV‐Burgers and KdV‐mKdV equations for finding the exact solutions. We use here the fractional complex transform accompanied by properties of local fractional calculus for reduction of fractional partial differential equations to ordinary differential equations. The obtained results are demonstrated by graphs for the new solutions. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
36.
Santanu Pyne Priyanka Sarkar Samita Basu Gobinda Prasad Sahoo Dipak Kumar Bhui Harekrishna Bar Ajay Misra 《Journal of nanoparticle research》2011,13(4):1759-1767
Synthesis of core @ shell (Au @ Ag) nanoparticle with varying silver composition has been carried out in aqueous poly vinyl
alcohol (PVA) matrix. Core gold nanoparticle (~15 nm) has been synthesized through seed-mediated growth process. Synthesis
of silver shell with increasing thickness (~1–5 nm) has been done by reducing Ag+ over the gold sol in the presence of mild reducing ascorbic acid. Characterization of Au @ Ag nanoparticles has been done
by UV–Vis, High resolution transmission electron microscope (HRTEM) and energy dispersive X-ray (EDX) spectroscopic study.
The blue shift of surface plasmon resonance (SPR) band with increasing mole fraction of silver has been interpreted due to
dampening of core, i.e. Au SPR by Ag. The dependence of nonlinear optical response of spherical core @ shell nanoparticles
has been investigated as a function of relative composition of each metal. Simulation of SPR extinction spectra based on quasi-static
theory is done. A comparison of our experimental and the simulated extinction spectra using quasi-static theory of nanoshell
suggests that our synthesized bimetallic particles have core @ shell structure rather than bimetallic alloy particles. 相似文献
37.
For distinct points x1,x2,…,xn in ℛ (the reals), letϕ[x1, x2,…,xn] denote the divided difference ofϕ. In this paper, we determine the general solutionϕ,g: ℛ → ℛ of the functional equationϕ[x1,x2,…,xn] =g(x1,+ x2 + … + xn) for distinct x1,x2,…, xn in ℛ without any regularity assumptions on the unknown functions. 相似文献
38.
Gamma-induced modifications in polycarbonate polymer have been studied in the dose range of 101–106 Gy. Thin films of polycarbonate have been irradiated with different gamma doses from a Co60 source. To monitor the modifications caused by gamma radiation, FT-IR, differential scanning calorimetry and X-ray diffraction studies have been performed. The studies have indicated that at the dose of 106 Gy, phenolic group forms through scissioning of ester linkage. Though the effect of radiation is most significant at the highest dose, the process of modifications starts at 103 Gy. Scissioning of the polymeric chain initiates a different morphological zone within the polymer matrix, and the polymer becomes more crystalline with increasing dose. Owing to chain scissioning, the mobility of the polymer increases, which in turn reduces the glass transition temperature of the polymer. 相似文献
39.
Satyabrata Sahoo Y.K. Ho 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(1):52-62
We present theoretical photoionization cross sections for He 1s2s 1S and He 1s2p 1P states in a Debye plasma environment by the complex coordinate rotation method, using a finite L2 basis set constructed from one electron Laguerre orbitals. The plasma environment is found to appreciably influence the photoionization cross sections near the ionization threshold. In this regard, the photoionization cross sections of isolated He are compared with other theoretical and experimental results. Our results are in good agreement with the previous results. A new minimum appears in the photoionization cross section curve for the metastable 1s2s 1S state. Results are given for the S- and D-wave partial photoionization for the excited 1s2p 1P state. 相似文献
40.
Bikash Sahoo 《Communications in Nonlinear Science & Numerical Simulation》2009,14(7):2982-2998
The steady Von Kármán flow and heat transfer of an electrically conducting non-Newtonian fluid is extended to the case where the disk surface admits partial slip. The fluid is subjected to an external uniform magnetic field perpendicular to the plane of the disk. The constitutive equation of the non-Newtonian fluid is modeled by that for a Reiner–Rivlin fluid. The momentum equations give rise to highly non-linear boundary value problem. Numerical solutions for the governing non-linear equations are obtained over the entire range of the physical parameters. The effects of slip, magnetic parameter and non-Newtonian fluid characteristics on the velocity and temperature fields are discussed in detail and shown graphically. Emphasis has been laid to study the effects of viscous dissipation and Joule heating on the thermal boundary layer. It is interesting to find that the non-Newtonian cross-viscous parameter has an opposite effect to that of the slip and the magnetic parameter on the velocity and the temperature fields. 相似文献