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41.
High Resolution Scanning Tunneling Microscopy of a 1D Coordination Polymer with Imidazole‐Based N,N,O Ligands on HOPG
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Dr. Nina V. Fischer Utpal Mitra Karl‐Georg Warnick Dr. Viacheslav Dremov Dr. Michael Stocker Thorsten Wölfle Dr. Wolfgang Hieringer Dr. Frank W. Heinemann Prof. Dr. Nicolai Burzlaff Prof. Dr. Andreas Görling Prof. Dr. Paul Müller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(37):11863-11869
Novel κ3‐N,N,O ligands tend to form 1D coordination polymer strands. Deposition of 1D structures on highly oriented pyrolytic graphite (HOPG) was achieved from diluted solutions and polymer strands have been studied on HOPG by AFM/STM. Single strands were mapped by STM and their electronic properties were subsequently characterized by current imaging tunneling spectroscopy (CITS). Periodic density functional calculations simulating a polymer strand deposited on a HOPG surface are in agreement with the zig‐zag structure indicated by experimental findings. Both the observed periodicity and the Zn–Zn distances can be reproduced in the simulations. Van der Waals interactions were found to play a major role for the geometry of the isolated polymer strand, for the adsorption geometry on HOPG, as well as for the adsorption energy. 相似文献
42.
Zdzisław Brzeźniak Utpal Manna Akash Ashirbad Panda 《Journal of Differential Equations》2019,266(10):6204-6283
In this work we consider a stochastic evolution equation which describes the system governing the nematic liquid crystals driven by a pure jump noise in the Marcus canonical form. The existence of a martingale solution is proved for both 2D and 3D cases. The construction of the solution relies on a modified Faedo–Galerkin method based on the Littlewood–Paley-decomposition, compactness method and the Jakubowski version of the Skorokhod representation theorem for non-metric spaces. We prove that in the 2-D case the martingale solution is pathwise unique and hence deduce the existence of a strong solution. 相似文献
43.
It is shown that dimension five non-renormalizable interactions can produce light Dirac neutrinos in an extension of the minimal
SU(5) GUT containing additional SU(5) singlets and global U(1) symmetries. 相似文献
44.
Maegawa T Kitamura Y Sako S Udzu T Sakurai A Tanaka A Kobayashi Y Endo K Bora U Kurita T Kozaki A Monguchi Y Sajiki H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(20):5937-5943
A mild and efficient ligand-free Suzuki-Miyaura coupling reaction catalyzed by heterogeneous Pd/C was developed. Aryl bromides and triflates undergo the cross-coupling with aryl boronic acids in excellent yields without the presence of any additives in aqueous media at room temperature. Aryl vinyl boronic acids are also applicable to this coupling reaction and provide the trans-stilbene derivatives in high yields. The application of wet-type Pd/C to the coupling reaction was achieved without any loss of activity under aerobic conditions, and the reuse of Pd/C is feasible for a fifth run without significant loss of activity. Inductively coupled plasma (ICP) mass-spectrometric analysis of the filtrate from the reaction mixture of 4-bromonitrobenzene with phenylboronic acid demonstrated that the palladium metal hardly leached into the solution within the limits of the detector (<1 ppm), thus suggesting that the present Suzuki-Miyaura reaction proceeded by heterogeneous catalysis. 相似文献
45.
Barnali Bhattacharya Ngangbam Bedamani Singh Utpal Sarkar 《International journal of quantum chemistry》2015,115(13):820-829
This report aims to explore the possibility of using graphyne derivatives as UV‐light protector. Boron (B) and nitrogen (N) atoms are systematically substituted into the structures, and we find that BN‐substituted analogs exhibit distinct characteristics compared with their parent two‐dimensional structure. Due to the presence of BN at different sites, the optical band gap is tuned from infrared to UV via visible region depending on substitution sites. These findings will lead the way to utilize these BN doped structures in various optoelectronic applications such as in hybrid solar cell, electroluminescence cell, light emitting cell, and as selective electromagnetic radiation absorber. The origin of this tunable optical response and band gap is explained in the light of partial density of states analysis and electron density distribution. The presence of strong absorption peak in UV region indicates that these materials may be used as an excellent candidate for UV light protection. © 2015 Wiley Periodicals, Inc. 相似文献
46.
Superfluid condensation of neutrinos of cosmological origin at a low enough temperature can provide simple and elegant solution to the problems of neutrino oscillations and the accelerated expansion of the universe. It would give rise to a late time cosmological constant of small magnitude and also generate tiny masses for the neutrinos as observed from their flavor oscillations. We show that carefully prepared beta decay experiments in the laboratory would carry signatures of such a condensation, and thus, it would be possible to either establish or rule out neutrino condensation of cosmological scale in laboratory experiments. 相似文献
47.
Anil Kumar Singh Dayal Singh Mehra Utpal Kumar Niyogi Sunil Sabharwal Rakesh Kumar Khandal 《Radiation Physics and Chemistry》2012,81(5):547-552
Polyurethane based pressure sensitive adhesive using monofunctional urethane acrylate and difunctional urethane acrylate has been made using electron beam irradiation. The effect of varying electron beam doses on the adhesion properties viz., peel adhesion, shear adhesion and initial tack has been studied. Effect of tackifier and crosslinkers viz., polymeric methylene diphenyl diisocynate, carbodiimide modified methylene diphenyl diisocynate and triallyl cynurate on adhesion properties as well as on moisture vapor transmission rate and gel content of the polyurethane based pressure sensitive adhesive has also been studied. It was found that with increasing dose, tackifier and crosslinkers concentration, all the adhesion properties viz., peel adhesion, shear adhesion strength and initial tack were increased upto a certain dose, concentration of tackifier and crosslinkers, reached a plateau and then levelled off with further increasing the dose, tackifier and crosslinkers concentration. Similarly, moisture vapor transmission rate was decreased and the gel content increased with increasing dose of electron beam. 相似文献
48.
Saibal Ray Utpal Mukhopadhyay Farook Rahaman Ruby Sarkar 《International Journal of Theoretical Physics》2013,52(12):4524-4536
Dark matter, the major component of the matter content of the Universe, played a significant role at early stages during structure formation. But at present the Universe is dark energy dominated as well as accelerating. Here, the presence of dark energy has been established by including a time-dependent Λ term in the Einstein’s field equations. This model is compatible with the idea of an accelerating Universe so far as the value of the deceleration parameter is concerned. Possibility of a change in sign of the deceleration parameter is also discussed. The impact of considering the speed of light as variable in the field equations has also been investigated by using a well known time-dependent Λ model. 相似文献
49.
In the supersymmetric standard model of particle interactions, R-parity nonconservation is often invoked to obtain nonzero neutrino masses. We point out here that such interactions of the supersymmetric particles would erase any pre-existing lepton or baryon asymmetry of the universe before the electroweak phase transition through the B+L violating sphaleron processes. We also point out that all models of radiative generation of neutrino masses suffer from the same problem. We then show how neutrino masses may be obtained in supersymmetry (assuming R-parity conservation) together with successful leptogenesis and predict the possible existence of new observable particles. 相似文献
50.
An unprecedented facile oxidation of 1,3,5-trisubstituted pyrazolines and Hantzsch 1,4-dihydropyridines (DHPs) to the corresponding pyrazoles and pyridines was observed, mediated by 3,4-dihydro-2H-pyran in air. The reaction showed excellent reactivity, functional group tolerance, and high yield without using any metal and/or halogen based oxidizing agents. 相似文献