排序方式: 共有31条查询结果,搜索用时 109 毫秒
1.
Yulia Shenberger Ortal Marciano Hugo E. Gottlieb 《Journal of Coordination Chemistry》2018,71(11-13):1985-2002
AbstractCopper transporter 1 (CTR1) is the main copper transporter in the eukaryotic system. CTR1 has several important roles: It binds Cu(II) ions that are present in the blood; it reduces those Cu(II) ions to Cu(I); and it subsequently transfers Cu(I) to the cytoplasmic domain, where the ion is delivered to various cellular pathways. Here, we seek to identify CTR1 binding sites for Cu(II) and Cu(I) and to shed light on the Cu(II)-to-Cu(I) reduction process. We focus on the first 14 amino acids of CTR1. This N-terminal segment is rich with histidine and methionine residues, which are known to bind Cu(II) and Cu(I), respectively; thus, this region has been suggested to have an important function in recruiting Cu(II) and reducing it to Cu(I). We utilize electron paramagnetic resonance (EPR) spectroscopy together with nuclear magnetic resonance (NMR) and UV-VIS spectroscopy and alanine substitution to reveal Cu(II) and Cu(I) binding sites in the focal 14-amino-acid segment. We show that H5 and H6 directly coordinate to Cu(II), whereas M7, M9, and M12 are involved in Cu(I) binding. This research is another step on the way to a complete understanding of the cellular copper regulation mechanism in humans. 相似文献
2.
Ortal Haik Francis Susai Amalraj Daniel Hirshberg Luba Burlaka Michael Talianker Boris Markovsky Ella Zinigrad Doron Aurbach Jordan K. Lampert Ji-Yong Shin Martin Schulz-Dobrick Arnd Garsuch 《Journal of Solid State Electrochemistry》2014,18(8):2333-2342
Thermodynamic instability of positive electrodes (cathodes) in Li-ion batteries in humid air and battery solutions results in capacity fading and batteries degradation, especially at elevated temperatures. In this work, we studied thermal interactions between cathode materials Li2MnO3, xLi2MnO3 .(1???x)Li(MnNiCo)O2,LiNi0.33Mn0.33Co0.33O2, LiNi0.4Mn0.4Co0.2O2, LiNi0.8Co0.15Al0.05O2 LiMn1.5Ni0.5O4, LiMn(or Fe)PO4, and battery solutions containing ethylene carbonate (EC) or propylene carbonate (PC), dimethyl carbonate (DMC) or ethylmethyl carbonate (EMC) and LiPF6 salt in the temperature range of 40–400 °C. It was found that these materials are stable chemically and well performing in LiPF6-based solutions up to 60 °C. The thermal decomposition of the electrolyte solutions starts >180 °C. The macro-structural transformations of cathode materials upon exothermic reactions were studied by transmission electron microscopy (TEM), X-ray difraction (XRD) and Raman spectroscopy. Differential scanning calorimetry (DSC) studies have shown that the exothermic reactions in the temperature range of 60–140 °C lead to partial decomposition of both the cathode material and electrolyte solution. The systems thus formed consisted of partially decomposed solutions and partially chemically delithiated cathode materials covered by reactions products. Thermal reactions terminate and this system reaches equilibrium at about 120 °C. It remains stable up to the beginning of the solution decomposition at about 180 °C. The increased content of surface Li2CO3 is found to significantly affect the thermal processes at high temperature range due to extensive exothermic decomposition at low temperatures. 相似文献
3.
L.B. Auerbach N. Haik V.L. Highland W.K. McFarlane R.J. Macek J.C. Pratt J. Sarracino R.D. Werbeck 《Physics letters. [Part B]》1980,90(3):317-318
A new search with increased detection efficiency has been made for the decay of the neutral pion into four photons, an allowed decay which is expected to be rare. We have observed no events, placing an upper limit on the branching ratio of 4.4 × 10?6 at 90% confidence level. 相似文献
4.
Tanaka F Chosrowjan H Taniguchi S Mataga N Sato K Nishina Y Shiga K 《The journal of physical chemistry. B》2007,111(20):5694-5699
Ultrafast fluorescence quenching of flavin in flavodoxin from Megasphaera elsdenii was investigated by means of a fluorescence up-conversion method. Fluorescence lifetimes of flavodoxin from M. elsdenii were estimated to be tau(1) approximately 165 fs (0.97%) and tau(2) approximately 10 ps (0.03%). Correlation of photoinduced electron-transfer rates (k(ET)) with averaged distances (D(av)) between isoalloxazine and nearby tryptophan or tyrosine was examined and obtained an empirical equation of ln k(ET) vs D(av) by means of a nonlinear least-squares method using reported data together with flavodoxin from M. elsdenii. The values of D(av) were calculated from X-ray structures of the flavoproteins. The ln k(ET) was approximately linear at D(av) shorter than 7 A. The model free empirical equation was expressed as ln k(ET) = 29.7 + (-0.327 D(av) + 2.84 x 10(-5))/(0.698 - D(av)(2)). We also analyzed the observed values of ln k(ET) with Marcus theory, but could not obtain reasonable results. Our analysis suggests that the average distance, rather than the shortest (edge to edge) distance or interplanar angles between the aromatics rings, is the key factor in the process of the photoinduced electron transfer in these flavoproteins. 相似文献
5.
Room‐temperature magnetization hysterisis measurements were conducted on Mn0.5Zn0.5GdxFe(2‐x)O4 ferrite nanoparticles, with x = 0, 0.5, 1.0, 1.5. The structure of this ferrite is normal spinel where the added of Gd3+ ions occupied the octahedral sites and replaces Fe3+ ions. The saturation magnetization was found to increase with the initial addition of the Gd3+ ions followed by a sharp decrease with further addition of Gd3+ ions. The Curie temperature was found to increase up to Gd3+ concentration of x = 1.0, and then decreases at x = 1.5. These results were attributed to the surface spins. Because the size of Gd3+ ions is larger than that of Fe3+ ions, the substitution of Fe3+ ions with the Gd3+ ions results in surface disorder which results in surface spins. A core‐shell magnetization model was introduced where several factors were combined to explain our results. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
6.
Ortal Yom Tov Shlomit Luvitch Havazelet Bianco‐Peled 《Journal of separation science》2010,33(11):1673-1681
A novel approach for enhancing protein recognition in molecularly imprinted hydrogel (MIH) is presented. This approach was developed based on the hypothesis that the number of specific binding sites created in the previously described MIH is very small, thus attempts to enhance the capacity result in most cases in additional non‐specific binding and loss of selectivity. Thus, blocking the non‐specific binding sites could lead to higher capacities and better selectivity. To test this hypothesis, MIH interpenetrating networks designed to block non‐specific binding sites were synthesized using two separate stages of polymerization. Re‐binding of the template protein (lysozyme) and a competitor protein (cytochrome C) was measured, and the results were compared with the similar experiment performed using a control non‐imprinted hydrogel and a “conventional” MIH. The imprinting efficacy of the MIH interpenetrating network was found to be much higher than that of the controls. Furthermore, competitive adsorption assays have demonstrated the superiority of the new formulation. 相似文献
7.
Human serum albumin magnetic microspheres containing 30% iron oxide particles were synthesized by a heat-stabilization process.
The average diameter, the size distribution and the morphology were characterized by scanning electron microscopy, atomic
force microscopy and transmission electron microscopy. The distribution of the iron oxide nanoparticles within the microspheres
was confirmed by the contrast obtained in the morphology by backscattered electron imaging in scanning electron microscopy.
Energy-dispersive X-ray spectroscopy showed the presence of iron in the microspheres. The cabbage like surface structure in
some of the microspheres obtained in scanning electron microscopy can be better understood by atomic force microscopy. This
peculiar surface structure in the microsphere may be due to the cross-linking in the protein molecule by heat. The amount
of iron oxide in the microsphere was analyzed by atomic absorption spectroscopy. The magnetic properties of the particles
were measured in a superconducting quantum interference device magnetometer.
Received: 12 September 2000 Accepted: 5 February 2001 相似文献
8.
Biomagnetic fluid dynamics is the study of the interaction of biological fluids with an applied steady magnetic field. Recently, several medical applications begin to utilize magnetic labeling of specific cells and targeted drug delivery using magnets. The magnetically labeled cells and the drug encapsulates are usually loaded in the blood stream and are directed toward a specific site by use of a magnet. In this paper, numerical simulation of biomagnetic fluid in the presence of a thrombus when exposed to magnetic field is presented. The finite analytic method is used to obtain the numerical simulation. It is found that the magnetic force causes a drastic change in the fluid behavior and the friction coefficient increases as the magnetic field strength increases. 相似文献
9.
Etacheri V Haik O Goffer Y Roberts GA Stefan IC Fasching R Aurbach D 《Langmuir : the ACS journal of surfaces and colloids》2012,28(1):965-976
The effect of FEC as a co-solvent on the electrochemical performance and surface chemistry of silicon nanowire (SiNW) anodes was thoroughly investigated. Enhanced electrochemical performance was observed for SiNW anodes in alkyl carbonates electrolyte solutions containing fluoroethylene carbonate (FEC). Reduced irreversible capacity losses accompanied by enhanced and stable reversible capacities over prolonged cycling were achieved with FEC-containing electrolyte solutions. TEM studies provided evidence for the complete and incomplete lithiation of SiNW's in FEC-containing and FEC-free electrolyte solutions, respectively. Scanning electron microscopy (SEM) results proved the formation of much thinner and compact surface films on SiNW's in FEC-containing solutions. However, thicker surface films were identified for SiNW electrodes cycled in FEC-free solutions. SiNW electrodes develop lower impedance in electrolyte solutions containing FEC in contrast to standard (FEC-free) solutions. The surface chemistry of SiNW electrodes cycled in FEC-modified and standard electrolytes were investigated using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The impact of FEC as a co-solvent on the electrochemical behavior of SiNW electrodes is discussed herein in light of the spectroscopic and microscopic studies. 相似文献
10.
Hassan Hejase Saleh S. Hayek Shahnaz Qadri Yousef Haik 《Journal of magnetism and magnetic materials》2012
Manganese zinc iron magnetic nanoparticles were synthesized by a co-precipitation method for application as hyperthermia inducing agents. The structure, morphology and magnetic properties of the nanoparticles are characterized using scanning electron microscopy, X-ray diffraction, and a superconducting quantum interference device. The magnetic properties being investigated include Curie temperature, saturation magnetization, remnant magnetization, coercive field, and hysteresis. The study showed that adjusting the Mn contribution to the particles contributed to the adjustment of all magnetic properties of the complex. 相似文献