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1.
Tee Lee Theng Zaharuddin Ahmad Che Abd Rahim Mohamed 《Journal of Radioanalytical and Nuclear Chemistry》2004,262(2):485-488
Polonium-210 has been measured in the soft parts of Anadara granosa purchased at Kuala Selangor, West Coast of Malaysia in August 2001, April 2002 and September 2002. It is shown that 210Po is non-uniformly distributed within cockles of various sizes (i.e., 2.5, 3.0, 3.5 and 4.0 cm of shell length) and the concentration
of 210Po in the soft parts of cockle was significantly different (p<0.05) due to sampling date. The highest value was observed in the smallest cockle with a shell length of 2.5 cm (411.6±26.16
Bq/g dry wt.). It is clear that there is an allometric relationship between 210Po activity concentration and individual cockle weight. This may reflect on the differences of metabolic rate and growth age
of cockles. The mean activity concentration of 210Po measured in Kuala Selangor filtered water were 1.75±0.17, 0.79±0.08 and 1.13±0.20 Bq/kg for August 2001, April 2002 and
September 2002, respectively. The yield concentration factors for 210Po in the soft parts of cockles varies from 27.3. 103 to 106.9. 103.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
An organopalladium complex containing ortho-metalated (S)-(1-(dimethylamino)ethyl)naphthalene as the chiral auxiliary has been used to promote the asymmetric hydrophosphination reactions between diphenylphosphine and (E)- or (Z)-diphenyl-1-propenylphosphine in high regio- and stereoselectivities under mild conditions. Hydrophosphination of (Z)-diphenyl-1-propenylphosphine with diphenylphosphine gave (S)-(-)-prophos as the major product. Using the same chiral metal template, the corresponding hydrophosphination reaction with (E)-diphenyl-1-propenylphosphine gave (R)-(+)-prophos predominantly. The hydrophosphination reactions generated the asymmetric diphosphines as bidentate chelates on the chiral naphthylamine palladium templates. The template products obtained undergo cis-trans isomerization in solution to form an equilibrium mixture of regioisomers. X-ray analysis of the major template products obtained from the hydrophosphination of (Z)-diphenyl-1-propenylphosphine reveals that the two regioisomers are cocrystallized in a 1:1 ratio. The naphthylamine auxiliary could be removed chemoselectively from the template products by treatment with concentrated hydrochloric acid to form the corresponding optically pure neutral complexes [(R)- or (S)-(prophos)PdCl(2)]. Subsequently, the (R)- and (S)-dichloro complexes undergo ligand displacement with aqueous cyanide to generate the corresponding optically pure diphosphine ligands in high yields. Mechanistic pathways explaining the stereoselectivity of the chiral organopalladium template promoted hydrophosphination reactions are also proposed. 相似文献
3.
Monika Mueller Maybelle Q. T. Loh Doris H. Y. Tee Yuansheng Yang Alois Jungbauer 《Applied biochemistry and biotechnology》2013,169(4):1431-1448
Proteins like immunoglobulin (IgGs) are prone to degradation by a variety of pathways. In this study, a stabilizing formulation for long-term storage of a panel of seven monoclonal IgGs was found using differential scanning calorimetry (DSC). In the chosen formulations, the IgGs were subjected to stress, accelerated and real-time storage, and analyzed by size exclusion chromatography to determine fragment and aggregate content, and fluorescence-activated cell sorting to measure immunoreactivity. All IgGs showed the greatest conformational stability near their isoelectric point which was enhanced by adding sorbitol, sucrose, glycine, and sodium chloride. Optimized formulations, found by DSC, containing 20 % sorbitol and 1 M glycine prevented IgG aggregation and fragmentation and conserved immunoreactivity against shear stress, multiple freeze–thaw cycles, accelerated storage at 37 °C, and 12 months storage at 4 and ?20 °C. Relatively poor thermal stability of the antigen-binding fragment domain was shown to limit storage stability of IgGs. This study confirms the predictive power of DSC to find storage formulations which protect IgGs during stress and long-term storage from aggregation and degradation. Liquid formulations found in this study may have a broad utility for other IgGs. 相似文献
4.
Kuan-Yu Lin Chak Hin Lam Xin-Hui Lin Jung-I Hsu Syuan-Yun Fan Dr. Nitesh K. Gupta Yu-Chun Lin Boon Khoon Tee Jui-Ping Li Dr. Jen-Kun Chen Prof. Dr. Kui-Thong Tan 《化学:亚洲杂志》2021,16(8):937-948
To date, various affinity-based protein labeling probes have been developed and applied in biological research to modify endogenous proteins in cell lysates and on the cell surface. However, the reactive groups on the labeling probes are also the cause of probe instability and nonselective labeling in a more complex environment, e. g., intracellular and in vivo. Here, we show that labeling probes composed of a sterically stabilized difluorophenyl pivalate can achieve efficient and selective labeling of endogenous proteins on the cell surface, inside living cells and in vivo. As compared with the existing protein labeling probes, probes with the difluorophenyl pivalate exhibit several advantages, including long-term stability in stock solutions, resistance to enzymatic hydrolysis and can be customized easily with diverse fluorophores and protein ligands. With this probe design, endogenous hypoxia biomarker in living cells and nude mice were successfully labeled and validated by in vivo, ex vivo, and immunohistochemistry imaging. 相似文献
5.
Yew Hoong Leong Jaguthsing Dindyal Tin Lam Toh Khiok Seng Quek Eng Guan Tay Sieu Tee Lou 《ZDM》2011,43(6-7):819-831
Problem solving is at the heart of the Singapore Mathematics curriculum. However, it remains a challenge for teachers to realise this curricular goal in practice. Here, we review the efforts of Singapore mathematics teacher educators in incorporating problem-solving (teaching) competency in teacher education and PD programmes. We discuss conceptual and practical issues, actions taken and changes made in building teachers?? capacity to enact a problem-solving curriculum in a school-based design experiment project. In the project, teachers learnt problem solving, observed and then carried out lessons, using the ??Mathematics Practical????akin to the science practical??as key to instruction and assessment. 相似文献
6.
S. Sepp K. Vaarmets J. Nerut I. Tallo E. Tee H. Kurig J. Aruväli R. Kanarbik E. Lust 《Journal of Solid State Electrochemistry》2017,21(4):1035-1043
Fuel cell electrodes were prepared from Pt nanocluster activated hierarchical microporous-mesoporous carbon powders. The carbon supports were synthesized from molybdenum carbide applying the high-temperature chlorination method. Six different synthesis temperatures within the range from 600 to 1000 °C were used for preparation of carbon supports. Thermogravimetric analysis, X-ray diffraction, low-temperature nitrogen sorption, and high-resolution scanning electron microscopy methods were used to characterize the structure of the electrode materials and symmetrical membrane electrode assemblies (MEAs). The MEAs prepared were used to conduct the proton exchange membrane fuel cell (PEMFC)single-cell measurements. The polarization and power density curves for single cells were calculated to evaluate the activity of the catalyst materials synthesized. The electrochemically active surface area (from 2.4 to 11.9 m2 g?1) was obtained in order to estimate the contact surface areas of platinum and Nafion® electrolyte. The values of the electrolyte resistance, polarization resistance, and cell degradation rate were calculated from electrochemical impedance spectroscopy data. The carbon materials synthesized within temperature range from 600 to 850 °C were found to be the most suitable supports for PEMFCs, having higher maximum power density values and better stability (cell potential degradation 240 μV h?1) than commercial carbon-based (Vulcan XC72; 670 μV h?1) single cells. 相似文献
7.
8.
G. J. Tee 《Numerische Mathematik》1964,6(1):142-159
Summary Finite-difference equations for the steady-state solution of a parabolic equation with periodic boundary conditions producep-cyclic matrices, wherep can be arbitrarily large. The periodic solution can be found by applying S.O.R. to the equations with thep-cyclic matrix, and this procedure is more economical than the standard step-by-step procedures for solving the parabolic equation. Bounds for the discretization error are found in terms of bounds for the known second derivatives of the boundary values. 相似文献
9.
G.J Tee 《Historia Mathematica》1984,11(3):327-329
10.
X-ray study of enhydrin bromohydrin, C23H29BrO10, reveals that the crystal has space groupP212121 with cell parametersa =10.08,b = 26.97, andc = 8.94 Å. There are four molecules in the unit cell. The structure was solved by direct methods, with three-dimensional CuK diffractometer data to = 75 °, and refined by block-diagonal least squares to anR index of 11.4% for 2254 reflections. The molecule is a germacronolide sesquiterpene having acis sterochemistry at the C(1), C(10) double bond and atrans configuration at the epoxide ring, C(4)-O-C(5). The absolute configuration established on the basis of the anomalous scattering of CuK. radiation by the bromine atom shows that the asymmetric atoms have the 4R, 5R, 6S, 7S, 8S, 9S, 20S, and 22S configurations. 相似文献