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141.
We describe imaging of calcium concentrations using the long-wavelength Ca2+ indicators, Calcium Green, Orange, and Crimson. The lifetimes of these probes were measured using the frequency-domain method and were found to increase from 50% to severalfold in response to calcium. The two-dimensional images of the calcium concentration were obtained using a new apparatus for fluorescence lifetime imaging (FLIM). We also describe procedures to correct for the position-dependent frequency response of the gain-modulated image intensifier used in the FLIM apparatus. Importantly, the FLIM method does not require the probe to display shifts in the excitation or emission spectra. Using the FLIM method, calcium imaging is possible using probes which display changes in lifetime in response to calcium. Consequently, calcium imaging is possible with excitation wavelengths ranging from 488 to as long as 620 nm, where autofluorescence and/or photochemical damage is minimal. These probes are also suitable for calcium measurements of single cells using lifetime-based flow cytometry. 相似文献
142.
火焰原子吸收法测定硅酸盐中铁钙镁 总被引:5,自引:0,他引:5
研究火焰原子吸收法测定硅基体中铁、钙、镁时,硅对待测元素吸收信号的干扰及表面活性剂对硅干扰的抑制作用。以十六烷基吡啶盐(CPC)作干扰抑制剂,FAAS法测定硅酸盐中铁、钙、镁等元素,灵敏、简便、无干扰。合成样品中铁、钙、镁的回收率分别为99.8%、101.3%和98.3%。 相似文献
143.
本文提出了一个精确,简便和快速测定大鼠心肌中微量钙的方法。采用硝酸与高氯酸消化心肌组织,火焰原子吸收法测定钙含量,钙的回收率为94.78±5.77%。 相似文献
144.
Sophia J. Makowski Daniel Gunzelmann Jürgen Senker Wolfgang Schnick Prof. Dr 《无机化学与普通化学杂志》2009,635(15):2434-2439
Calcium hydrogenmelonate heptahydrate Ca[HC6N7(NCN)3] · 7H2O was obtained by metathesis reaction in aqueous solution. The structure of the molecular salt was elucidated by single‐crystal X‐ray diffraction. The crystal structure consists of alternating layers of planar monopronated melonate ions, Ca2+ and crystal water molecules. The anions of adjacent layers are staggered so that no π–π stacking occurs. The melonate entities are interconnected by hydrogen bonds within and between the layers. Ca[HC6N7(NCN)3] · 7H2O was investigated by solid‐state NMR and FTIR spectroscopy, TG and DTA measurements. 相似文献
145.
采用静电纺丝法制备(1-x)Ni0.5Zn0.5Fe2O4-(x)Pb(Zr0.52Ti0.48)O3(简称为(1-x)NZFO-(x)PZT, x=0.1、0.2、0.3、0.4、0.5)磁电复合纳米纤维, 研究了PZT含量对复合纳米纤维结构、电磁特性及微波吸收性能的影响。所有样品均由尖晶石结构NZFO和钙钛矿结构PZT两相所组成。由于NZFO磁损耗与PZT介电损耗的协同效应及界面效应的加强, 适量PZT相的引入可改善复合纳米纤维吸波涂层的电磁阻抗匹配和衰减特性, 提高微波吸收性能。x=0.3和0.4的复合纳米纤维分别在低频和高频范围表现出最强的微波吸收能力。当涂层厚度为2.5~5.0 mm时, x=0.3样品的最小反射损耗在6.1 GHz处达-77.2 dB, 反射损耗小于-10 dB的有效吸收带宽为11.2 GHz(2.8~12.9和16.9~18 GHz);x=0.4样品的最小反射损耗位于18 GHz处为-37.6 dB, 有效吸收带宽达到12.5 GHz(3.3~12.5和14.7~18 GHz)。 相似文献
146.
147.
Linghao HeLu Yao Jing SunWei Wu Jie YangLifang Cai Rui Song Yongmei HaoZhi Ma Wei Huang 《Polymer Degradation and Stability》2011,96(7):1187-1193
The aim of this investigation is to obtain a polymer-based hybrid material with biodegradability, biocompatibility, and good mechanical properties and this object was realized via. in-situ introduction of the unmodified calcium carbonate (CaCO3) into a poly(l-lactic acid) (PLLA) matrix. As verified by the measurements from scanning electron microscopy (SEM), optical microscopy, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), the hybrid films which possesses a uniform dispersion of calcium carbonate CaCO3 in nano-meter scale, mechanically robustness and thermal stability could be fabricated by a mineralization-alike process. For example, the storage modulus increases from 441 MPa of neat PLLA to 1034 MPa of hybrid film containing 2% (w/w) CaCO3. In addition, the hybrid films display a significant improvement in its UV-exposure resistance. 相似文献
148.
We have used calculations based on density functional theory to investigate the energetics of hydrogen absorption in calcium-intercalated graphites. We focus particularly on the absorption energy and the stability of the hydrogenated material with respect to decomposition into graphite and calcium hydride, which is essential if this material is to be used for practical H2 storage. The calculations are performed with two commonly used approximations for the exchange-correlation energies. Our calculations confirm earlier predictions that the absorption energy is approximately −0.2 to −0.4 eV, which is favourable for practical use of Ca-intercalated graphite as a hydrogen storage medium. However, we find that the hydrogenated material is strongly unstable against decomposition. Our results therefore explain recent experiments which show that H2 does not remain stable in CaC6 but instead forms a hydride plus graphite. 相似文献
149.
150.
Calcium selective electrodes with various membrane formulations were studied in solutions containing CaCl2 and sodium dodecylsulfate (NaDS). It is shown that electrodes based on neutral ionophores ETH 1001 and ETH 129 cannot be used as Ca2+ ion sensors in these solutions because of strong anion interference from DS? anion. Among other formulations, that based on calcium bis(tetramethylbutylphenyl)phosphate in tri(2‐ethylhexyl)phosphate appear the most promising. The interpretation of the ISE response in solutions under study relied on a novel approach which considers three forms of calcium: Ca2+ free ions, Ca in Ca(DS)2 precipitate, and Ca2+ bound by the DS? micelles. Data needed for the respective calculations were obtained by DS? selective electrode based on tetradecylammonium, and Na+ selective glass electrode. 相似文献