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701.
The electrophoresis of a charge-regulated spherical particle at an arbitrary position in a charged spherical cavity is modeled under conditions of low surface potential (<25 mV) and weak applied electric field (<25 kV/m). The charged cavity allows us to simulate the effect of electroosmotic flow, and the charge-regulated nature of the particle permits us to model various types of surface. The problem studied previously is reanalyzed based on a more rigorous electric force formula. In particular, the influences of various types of charged conditions on the electrophoretic behavior of a particle and the roles of all the relevant forces acting on the particle are examined in detail. Several new results are found. For instance, the mobility of a particle has a local minimum as the thickness of a double layer varies, which is not seen in the cases where the surface of a particle is maintained at a constant potential and at a constant charge density. 相似文献
702.
Chen PH Tseng YH Mou Y Tsai YL Guo SM Huang SJ Yu SS Chan JC 《Journal of the American Chemical Society》2008,130(9):2862-2868
Statherin is an active inhibitor of calcium phosphate precipitation in the oral cavity. For many studies of the interaction between statherin and hydroxyapatite (HAp), the samples are prepared by a direct mixing of statherin or its fragment with well-crystalline HAp crystals. In this work, the HAp sample is precipitated in the presence of peptide fragment derived from the N-terminal 15 amino acids of statherin (SN-15). The in situ prepared HAp crystallites are nanosized, leading to a significant increase of the peptide amount adsorbed on the HAp surface. The enhancement in NMR sensitivity allows, for the first time, the measurement of a two-dimensional 13C-13C correlation spectrum for a 13C uniformly labeled peptide sample adsorbed on mineral surface. The measurement time is about 18.5 h at a field strength of 7.05 T. Preliminary results suggest that there may exist two different mechanisms for the interaction between SN-15 and HAp. In addition to the one which will cause a conformational change near the N-terminal, SN-15 may also be absorbed on the HAp surface by simple electrostatic interaction, without any significant conformational changes of the peptides. 相似文献
703.
Prof. Weibo Hua Jilu Zhang Dr. Suning Wang Yi Cheng Dr. Hang Li Dr. Jochi Tseng Prof. Zhonghua Wu Dr. Chong-Heng Shen Dr. Oleksandr Dolotko Hao Liu Dr. Sung-Fu Hung Prof. Wei Tang Prof. Mingtao Li Dr. Michael Knapp Prof. Helmut Ehrenberg Dr. Sylvio Indris Prof. Xiaodong Guo 《Angewandte Chemie (International ed. in English)》2023,62(12):e202214880
Ni-rich layered oxides are one of the most attractive cathode materials in high-energy-density lithium-ion batteries, their degradation mechanisms are still not completely elucidated. Herein, we report a strong dependence of degradation pathways on the long-range cationic disordering of Co-free Ni-rich Li1−m(Ni0.94Al0.06)1+mO2 (NA). Interestingly, a disordered layered phase with lattice mismatch can be easily formed in the near-surface region of NA particles with very low cation disorder (NA-LCD, m≤0.06) over electrochemical cycling, while the layered structure is basically maintained in the core of particles forming a “core–shell” structure. Such surface reconstruction triggers a rapid capacity decay during the first 100 cycles between 2.7 and 4.3 V at 1 C or 3 C. On the contrary, the local lattice distortions are gradually accumulated throughout the whole NA particles with higher degrees of cation disorder (NA-HCD, 0.06≤m≤0.15) that lead to a slow capacity decay upon cycling. 相似文献
704.
Po-Sen Tseng Dr. Chennaiah Ande Prof. Dr. Kelley W. Moremen Prof. Dr. David Crich 《Angewandte Chemie (International ed. in English)》2023,62(8):e202217809
Substrate side chain conformation impacts reactivity during glycosylation and glycoside hydrolysis and is restricted by many glycosidases and glycosyltransferases during catalysis. We show that the side chains of gluco and manno iminosugars can be restricted to predominant conformations by strategic installation of a methyl group. Glycosidase inhibition studies reveal that iminosugars with the gauche,gauche side chain conformations are 6- to 10-fold more potent than isosteric compounds with the gauche,trans conformation; a manno-configured iminosugar with the gauche,gauche conformation is a 27-fold better inhibitor than 1-deoxymannojirimycin. The results are discussed in terms of the energetic benefits of preorganization, particularly when in synergy with favorable hydrophobic interactions. The demonstration that inhibitor side chain preorganization can favorably impact glycosidase inhibition paves the way for improved inhibitor design through conformational preorganization. 相似文献
705.
Tseng YH Mou Y Chen PH Tsai TW Hsieh CI Mou CY Chan JC 《Magnetic resonance in chemistry : MRC》2008,46(4):330-334
We demonstrate that glutaric acid can be used to prepare nanorods of hydroxyapatite under hydrothermal condition at 100 degrees C with a Ca(2+):glutaric acid molar ratio of 1:4. Frequency-switched Lee-Goldburg irradiation is employed to obtain high-resolution (31)P{(1)H} correlation spectra of the reaction mixture at two different reaction periods, from which it is shown that octacalcium phosphate is the precursor phase of the final hydroxyapatite product. In addition, the spectra show that a substantial amount of water molecules is trapped between the glutaric acid and the hydroxyapatite surface, indicating that water molecules may play a prominent role in the noncovalent interaction of the glutaric acid and the HAp surface. 相似文献
706.
A thieno [3,2-b] thiophene-based planar liquid crystal molecule, C12-PTTT, which possesses the characteristics of an organic field-effect transistor (OFET), was synthesised and its mesomorphic properties were studied by polarising optical microscopy and differential scanning calorimetry. A wide temperature range for a highly oriented smectic phase was observed. OFET devices made under various conditions, such as self-assembled monolayer treatment and alignment treatment, and with micro-channel structures, were fabricated to measure the electrical properties. Among different OFET device conditions, the best electric carrier mobility for C12-PTTT was 0.038 cm2?V?1?s?1. 相似文献
707.
This study developed an affinity-gradient nano-stationary phase (AG-NSP) for protein analysis using nanofluidic capillary electrochromatography (nano-CEC) conjugated with matrix assisted laser desorption ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS). The AG-NSP can be used for protein pre-separation in nano-CEC and as a matrix carrier for protein analysis in MALDI-TOF-MS. A hydrophobicity gradient in AG-NSP was photochemically formed by grafting 4-azidoaniline hydrochloride on vertically arrayed multi-wall carbon nanotubes (MWCNTs) through gray-level exposure to UV light. The reversed-phase gradient stationary phase in AG-NSP was tailored according to the properties of the mobile phase gradient in capillary electrochromatography. As a result, the operation of the system is easily automated using a single buffer solution without the need for multiple solvents for elution. The use of nano-CEC with AG-NSP demonstrated excellent separation efficiency and high resolution for various types of DNA/protein/peptide. MALDI-TOF-MS analysis was then performed directly on the separated proteins and peptides on the chip. The proposed system was then used for the detection of three types of proteins with different molecular weights and PI values, including Cytochrome c (12,360, pI = 10), Lysozyme (14,300, pI = 11), and BSA (86,000, pI = 5)), and digested IgG fragments. The proposed system provided resolution of 1000 Da for the proteins in this study and the separation of digested IgG fragments at a low concentration of 1.2 pmol μL−1. 相似文献
708.
This study employs the Space-Time Conservation Element and Solution Element (CE/SE) method to determine the influence of downstream
flow conditions on Mach stem height. The results indicate that the Mach stem height depends on the incident shock wave angle
and the distance between the trailing edge and the symmetry plane. Furthermore, it is shown that the downstream length ratio
and the trailing edge angle do not affect the Mach stem height nor the Mach reflection (MR) configuration, and the Space-Time
Conservation Element and Solution Element method is able to simulate the MR as well as many other numerical schemes.
Communicated by K. Takayama
PACS 47.40.Nm 相似文献
709.
Wu Jeffrey C.S. Tseng I.-Hsiang Chang Wan-Chen 《Journal of nanoparticle research》2001,3(2-3):113-118
Nanoparticles of titania and copper-loaded titania were synthesized by a refined sol-gel method using titanium butoxide. Unlike the conventional sol-gel procedure of adding water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Following the hydrolysis, Cu/TiO2 was prepared by adding copper chloride to titania sol. The sol was dried, then calcined at 500°C to remove organics and transformed to anatase titania which was verified by XRD. Cu/TiO2 was further hydrogen-reduced at 300°C. The recovery of Ti was exceeded by an average of 95% from titanium butoxide. TEM micrographs show that the Cu/TiO2 particles are near uniform. The average crystallite sizes are 17–20 nm estimated from the peak broadening of XRD spectra. The bandgaps of TiO2 and reduced Cu/TiO2 range from 2.70 to 3.15 eV estimated from the diffusive reflective UV-Vis spectra. XPS analysis shows that Cu 2p3/2 is 933.4 eV indicating primary Cu2O form on the TiO2 supports. The binding energy of Ti does not exhibit chemical shift suggesting negligible interaction of Cu cluster and TiO2 support. 相似文献
710.
Gwo-Wei Tseng Maw-Cherng Suen Jhy-Der Chen Jiunn-Jer Hwang Yui Whei Chen-Yang Tai-Chiun Keng Ju-Chun Wang 《中国化学会会志》1999,46(4):545-550
The red complex trans-Mo2(O2CCH3)2(μ-dppa)2(BF4)2, 1 , was prepared by reaction of [Mo2(O2CCH3)2(CH3CN)6][BF4]2 with dppa (dppa = Ph2PN(H)PPh2) in THF. The reactions of Mo2(O2C(CH2)nCH3)4 with dppa and (CH3)3SiX (X = Cl or Br) afforded the complexes trans-Mo2X2(O2C(CH2)nCH3)2(μ-dppa)2 (X = Cl, n = 2, 2; X = Br, n = 2, 3; X = Cl, n = 10, 4 ; X = Cl, n = 12, 5 ). Their UV-vis, IR and 31P{1H}-NMR spectra have been recorded and the structures of 1, 2 and 3 have been determined. Crystal data for 1 : space group P21/n, a = 12.243(1) Å, b = 17.222(1) Å, c = 13.266(1) Å, β = 95.529(1)°, V = 2784.1(6) Å3, Z = 2, with final residuals R = 0.0509 and Rw = 0.0582. Crystal data for 24CH3Cl2: space group P21/n, a = 13.438(1) Å, b = 19.276(1) Å, c = 14.182(1) Å, β = 111.464(1)°, V = 3418.9(6) Å3, Z = 2, with final residuals R = 0.0492 and Rw = 0.0695. Crystal data for 3·4CH2Cl2: space group P21/n, a= 13.579(1) Å, b = 19.425(1) Å, c = 14.199(1) Å, β = 111.881(2)°, V = 3475.6(7) Å3, Z = 2, with final residuals R = 0.0703 and Rw = 0.0851. Comparison of the structural data shows that the effect of the axial ligand on weakening the Mo-Mo bond strength is X? > CH3CN > BF4?. The Tm values are 121.7 °C for 2 , 111.1 °C for 3 and 91.5 °C for 5 , respectively. 相似文献