Transition metal(II) complexes of 1-(α-hydroxynaphthyl)-2-(3′-methyl-5′-mercapto-1′,2′,4′-triazole)-2-aza-ethane

Summary Binuclear metal complexes of the type [M(HMTE)-(H₂O)₂]₂, where HMTE=1-(-hydroxynaphthyl)-2-(3-methyl-5-mercapto-1,2,4-triazolc)2-aza-ethane and M-Cu^II, Co^II, Ni^II and Mn^II have been prepared and characterized. An octahedral geometry around the metals is proposed. The complexes have been screened as possible fungicides.     

Quantum dynamics of Br + HD reaction

In this article we report the results of three-dimensional time-dependent quantum wavepacket calculations carried out for the Br + HD( v = 0, j = 0) reaction in the collision energy range 0.0-1.2 eV. An accurate potential energy surface computed by Kurosaki was used for the dynamical calculations. Both reactive channels, BrH + D and BrD + H, show vibrational enhancement of the reaction cross sections. For the three initial vibrational states considered, the production of BrD channel dominates over that of BrH for the considered collision energy range. The two arrangement channels exhibit different initial rotational state dependence. The cross section for the formation of BrD is almost independent of j whereas the same for the formation of BrH increases with increase in j. A comparison with the results on an e-LEPS surface shows that the two surfaces behave very differently with respect to the cross section for the initial rotational states.     

Radical Chain Breaking Bis(ortho-organoselenium) Substituted Phenolic Antioxidants

The presence of a chalcogen atom at the ortho-position of phenols enhances their radical chain-breaking activity. Here, a copper(I)-catalyzed reaction of 2,6-dibromo- and 2,6-diiodophenols with diorganodiselenides has been studied for the introduction of two organoselenium substituents at both ortho-positions of the phenolic radical chain-breaking antioxidants, which afforded 2,6-diorganoseleno-substituted phenols in 80–92% yields having electron-donating CH₃, and electron-withdrawing CN and CHO functionalities. Additionally, 2,6-diiodophenols with electron-withdrawing CHO and CN groups also afforded novel 5,5′-selenobis(4-hydroxy-3-(phenylselanyl)benzaldehyde) and 5,5′-selenobis(4-hydroxy-3-(phenylselanyl)benzonitrile) consisting of three selenium and two phenolic moieties along with 2,6-diorganoseleno-substituted phenols has been synthesized. The electron-withdrawing CHO group has been reduced by sodium borohydride to the electron-donating alcohol CH₂OH group, which is desirable for efficient radical quenching activity of phenols. The developed copper-catalyzed reaction conditions enable the installation of two-arylselenium group ortho to phenolic radical chain-breaking antioxidants, which may not be possible by conventional organolithium-bromine exchange methods due to the sluggish reactivity of trianions (dicarba and phenoxide anion), which are generated by the reaction of organolithium with 2,6-dibromophenols, with diorganodiselenides. The antioxidant activities of the synthesized bis and tris selenophenols have been accessed by DPPH, thiol peroxides, and singlet oxygen quenching assay. The radical quenching antioxidant activity has been studied for the synthesized compounds by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The bis-selenophenols show comparable radical deactivating activity, while tris seleno-bisphenols show higher radical deactivating activity than α-tocopherol. Furthermore, the tris seleno-bisphenol shows comparable peroxide decomposing activity with ebselen molecules.     

Effect of skimming layer in an electroosmotically driven viscoelastic fluid flow over charge modulated walls

We report a numerical study on the effect of the skimming layer in an EOF of Oldroyd-B fluid over charge modulated walls. Three types of flow conditions were identified on the basis of the relative thickness of the skimming layer and the electrical double layer. We observe maximum slip velocity magnitude when the skimming layer thickness is very less than the thickness of the electrical double layer. For higher skimming layer thickness compared to the thickness of electrical double layer, slip velocity magnitude attenuates, and the polymeric stress inside the skimming layer becomes zero. Enhanced fluid elasticity generates asymmetric flow structures inside the microchannel, which can also be achieved by imposing an asymmetric surface charge along the channel walls. Our present analysis highlights the complex flow dynamics of the EOF of biofluids/polymeric fluids with a near-wall region depleted of macro-molecules.     

Effect of heating on the suppression of tearing modes in tokamaks

The suppression of (neoclassical) tearing modes is of great importance for the success of future fusion reactors like ITER. Electron cyclotron waves can suppress islands, both by driving noninductive current in the island region and by heating the island, causing a perturbation to the Ohmic plasma current. This Letter reports on experiments on the TEXTOR tokamak, investigating the effect of heating, which is usually neglected. The unique set of tools available on TEXTOR, notably the dynamic ergodic divertor to create islands with a fully known driving term, and the electron cyclotron emission imaging diagnostic to provide detailed 2D electron temperature information, enables a detailed study of the suppression process and a comparison with theory.     

Direct measurement of quantum phase gradients in superfluid 4He flow

We report a new kind of experiment in which we generate a known superfluid velocity in a straight tube and directly determine the phase difference across the tube's ends using a superfluid matter wave interferometer. By so doing, we quantitatively verify the relation between the superfluid velocity and the phase gradient of the condensate macroscopic wave function. Within the systematic error of the measurement (approximately 10%) we find nu(s)=Planck's/m4InvertedDeltaphi.     

Diastereoselective addition of planar N-heterocycles to vinyl sulfone-modified carbohydrates: a new route to isonucleosides

Michael-type addition reactions of planar N-heterocycles at the C-2 positions of vinyl sulfone-modified carbohydrates provide an efficient and general route for the carbon-N-heterocycle bond formation. Therefore, the addition pattern of planar heterocycles, such as imidazole, triazole, thymine, and adenine to 3-C-phenylsulfonyl-hex-2-enopyranosides (1α/1β) and 3-C-p-toluenesulfonyl-pent-2-enofuranosides (2α/2β) was studied for developing a general methodology for the synthesis of new classes of isonucleosides possessing a carbon-N-heterocycle linkage at C-2 positions of furanosyl and pyranosyl sugars. To a great extent, the anomeric configurations of the starting vinyl sulfones play crucial roles in deciding the diastereoselectivity of addition of heterocycles. However, the trityl protected 3-C-p-toluenesulfonyl-hex-2-enopyranosides (33α/33β) were judged to be more practical starting materials for desulfonylation and deprotection for the synthesis of a new class of thymine and adenine deoxyisonucleosides.     

Insight into Bioactivity of In-situ Trapped Enzyme-Covalent-Organic Frameworks

Selecting a suitable support material for enzyme immobilization with excellent biocatalytic activity and stability is a critical aspect in the development of functional biosystems. The highly stable and metal-free properties of covalent-organic frameworks (COFs) make them ideal supports for enzyme immobilization. Herein, we constructed three kinds of COFs via a biofriendly and one-pot synthetic strategy at room temperature in aqueous solution. Among the three developed COFs (COF-LZU1, RT-COF-1 and ACOF-1), the horseradish peroxidase (HRP)-incorporated COF-LZU1 is found to retain the highest activity. Structural analysis reveals that a weakest interaction between the hydrated enzyme and COF-LZU1, an easiest accessibility by the COF-LZU1 to the substrate, as well as an optimal conformation of enzyme together promote the bioactivity of HRP-COF-LZU1. Furthermore, the COF-LZU1 is revealed to be a versatile nanoplatform for encapsulating multiple enzymes. The COF-LZU1 also offers superior protection for the immobilized enzymes under harsh conditions and during recycling. The comprehensive understanding of interfacial interactions of COF host and enzyme guest, the substrate diffusion, as well as the enzyme conformation alteration within COF matrices represents an opportunity to design the ideal biocatalysts and opens a broad range of applications of these nanosystems.     

The design of polyvalent therapeutics

This article reviews recent developments in the design of polyvalent ligands for in vivo applications. Topics discussed include the design of polyvalent inhibitors of toxins and viruses, the use of polyvalency for targeted drug delivery and imaging, and applications of polyvalency for enhancing or suppressing immune responses.     

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为了分析ITER第一壁模块试制过程中Be/Cu界面经热等静压扩散连接后出现的不可接受的大尺寸缺陷,对Be/Cu连接失效的模块进行了破坏性试验.首先采用线切割对模块进行解剖,并对连接界面缺陷区域及非缺陷区域通过金相观察、SEM观察及能谱分析进行对比,初步确定了界面连接的失效机理.