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531.
The proteasome is an essential evolutionary conserved protease involved in many regulatory systems. Here, we describe the synthesis and characterization of the activity-based, fluorescent, and cell-permeable inhibitor Bodipy TMR-Ahx(3)L(3)VS (MV151), which specifically targets all active subunits of the proteasome and immunoproteasome in living cells, allowing for rapid and sensitive in-gel detection. The inhibition profile of a panel of commonly used proteasome inhibitors could be readily determined by MV151 labeling. Administration of MV151 to mice allowed for in vivo labeling of proteasomes, which correlated with inhibition of proteasomal degradation in the affected tissues. This probe can be used for many applications ranging from clinical profiling of proteasome activity, to biochemical analysis of subunit specificity of inhibitors, and to cell biological analysis of the proteasome function and dynamics in living cells.  相似文献   
532.
We study linear operators T on Banach spaces for which there exists a C0-semigroup (T(t))t≥0 such that TT(1). We present a necessary condition in terms of the spectral value 0 and give classes of examples for which such a C0-semigroup does or does not exist. Received: 22 December 2008, Revised: 7 April 2009  相似文献   
533.
This work demonstrates the capabilities of nanoscale secondary-ion mass spectrometry, using the Cameca NanoSIMS50 ion microprobe, to detect and image the copper-ion distribution in microalgal cells exposed to nanomolar and micromolar copper concentrations. In parallel to 63Cu secondary-ion maps, images of 12C, 12C14N, and 31P secondary ions were collected and analysed. A correlation of 63Cu secondary-ion maps with those found for 12C14N and 31P demonstrated the possible association of Cu with cell components rich in proteins and phosphorus. The results highlighted the potential of NanoSIMS for intracellular tracking of essential trace elements such as Cu in single cells of the microalga Chlorella kesslerii. Figure  12C14N-, 63Cu- secondary-ion distributions in algal cell  相似文献   
534.
The formation of an appropriate solid electrolyte interphase (SEI) at the anode of a sodium battery is crucially dependent on the electrochemical stability of solvent and electrolyte at the redox potential of Na/Na+ in the respective system. In order to determine entropic contributions to the relative stability of the electrolyte solution, we measure the reaction entropy of Na metal deposition for diglyme (DG) and propylene carbonate (PC) based electrolyte solutions by electrochemical microcalorimetry at single electrodes. We found a large positive reaction entropy for Na+ deposition in DG of ΔR 234 J mol−1 K−1 (c.f.: ΔR 83 J mol−1 K−1), which signals substantial entropic destabilization of Na+ in DG by about 0.73 eV, thus increasing the stability of solvent and electrolyte relative to Na+ reduction. We attribute this strong entropic destabilization to a highly negative solvation entropy of Na+, due to the low dielectric constant and high freezing entropy of DG.  相似文献   
535.
536.
Nano-sized latex particles as organic supports for metallocenes applied in olefin polymerizations are introduced. The particles are functionalized with nucleophilic surfaces such as polyethylenoxide (PEO), polypropyleneoxide (PPO) or pyridine units allowing an immobilization of the metallocene catalysts via a non-covalent immobilization process. The latices are obtained by emulsion or miniemulsion polymerization with styrene, divinylbenzene as the crosslinker, and either PEO or PPO functionalized styrene or 4-vinylpyridine for surface functionalization. The supported catalysts, e.g. [Me2Si(2MeBenzInd)2ZrCl2/MAO] on PPO containing latices or Cp2ZrMe2/([Ph3C][B(C6F5)4]) on pyridine functionalized materials were tested in ethylene polymerizations. Remarkably, high activities and excellent product morphologies were obtained. The influence of the degree of surface functionalization on activity and productivity was investigated. Furthermore, the fragmentation of the catalyst was studied by electron microscopy using bismuth-labeled latex particles or by fluorescence and confocal fluorescence microscopy using dye-labeled supports. Finally, a self-immobilizing catalyst/monomer system is presented. It is demonstrated that by using PEO-functionalized olefins, the metallocenes were immobilized on the monomers. Subjecting these mixtures to an ethylene copolymerization, again high activities and productivities as well as polyolefin beads with high bulk densities are observed, indicating that an extra supporting process for controlling the product size and shape of the polyolefins is not necessary for these monomers.  相似文献   
537.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.  相似文献   
538.
Photoexcitation of trapped ions by Hermite–Gaussian (HG) modes from guided beam structures is proposed and investigated theoretically. In particular, simple analytical expressions for the matrix elements of induced atomic transitions are derived that depend both on the parameters of HG beams and on the geometry of an experiment. By using these general expressions, the 2 S 1 / 2 2 F 7 / 2 $^{2}S_{1/2} \rightarrow \; ^{2}F_{7/2}$ electric octupole (E3) transition is investigated in an Yb+ ion, localized in the low–intensity center of the HG10 and HG01 beams. It is shown how the corresponding Rabi frequency can be enhanced by properly choosing the polarization of incident light and the orientation of an external magnetic field, which defines the quantization axis of a target ion. The calculations, performed for experimentally feasible beam parameters, indicate that the achieved Rabi frequencies can be comparable or even higher than those observed for the conventional Laguerre–Gaussian (LG) modes. Since HG-like modes can be relatively straightforwardly generated with high purity and stability from integrated photonics, these results suggest that they may form a novel tool for investigating highly-forbidden atomic transitions.  相似文献   
539.
An automated high throughput multidimensional reaction screening platform based on an inline Fourier-transform infrared spectroscopy is presented. By combining flow chemistry, machine automation and inline analysis, the platform is able to screen reactions in multidimensions (residence time, monomer concentration, degree of polymerization, reaction temperature and monomer conversion) rapidly and efficiently way. Kinetic data libraries associated with high data precision (absolute error <4 %), high reproducibility and high data density are built with ease from the platform. To test the method, we screened the reversible addition-fragmentation chain transfer polymerization of methyl acrylate in unmatched detail, and the ring opening metathesis polymerization of methyl-5-norbornene-2-carboxylate. The method we introduce is a key step in providing “big data” for data driven research in the future, and already at present allows for precise prediction of reaction outcomes within the high-dimensional chemical parameter space that is screened.  相似文献   
540.
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