Intracellular signal transduction relies on spatial and temporal signal transmitter dynamics. To clarify the correlations of these transmitter molecules, multicolor-imaging has been widely used. However, in the case of applying multiple indicators in a cell, spectral overlap of the indicators prevents accurate quantitative analysis. Moreover, the invasive (toxic) effect, the localization, the metabolism, as well as photobleaching of these indicators complicate the situation. Here, we show that single-molecular multifluorescent probes can overcome these problems. While intracellular calcium plays a critical role as a signal transmitter and magnesium acts as a cofactor in many situations, the correlations between the two cations are now the main issue. We designed and synthesized a Ca2+-Mg2+ responsive multifluorescent probe, KCM-1. KCM-1 shows a spectral blue shift upon complexation to Ca2+ and a red shift to the presence of Mg2+. With data analyzed at different excitation wavelengths, the concentrations of Ca2+ and Mg2+ are simultaneously quantified. Furthermore, by using the AM-ester method, intracellular Ca2+ and Mg2+ concentrations are simultaneously imaged. Such a type of intracellular multiple analyte imaging by a single-molecular multifluorescent probe is successfully demonstrated for the first time. 相似文献
Oxynitrides are promising visible‐light‐responsive photocatalysts, but their structures are almost confined with three‐dimensional (3D) structures such as perovskites. A phase‐pure Li2LaTa2O6N with a layered perovskite structure was successfully prepared by thermal ammonolysis of a lithium‐rich oxide precursor. Li2LaTa2O6N exhibited high crystallinity and visible‐light absorption up to 500 nm. As opposed to well‐known 3D oxynitride perovskites, Li2LaTa2O6N supported by a binuclear RuII complex was capable of stably and selectively converting CO2 into formate under visible light (λ>400 nm). Transient absorption spectroscopy indicated that, as compared to 3D oxynitrides, Li2LaTa2O6N possesses a lower density of mid‐gap states that work as recombination centers of photogenerated electron/hole pairs, but a higher density of reactive electrons, which is responsible for the higher photocatalytic performance of this layered oxynitride. 相似文献
Carbon dioxide has been reduced to methanol with an electrochemical photocell composed of an n-TiO2 photoanode and a metal complex-confined platinum cathode in the presence of homogeneous catalysts. The feasibility of the reduction of CO2 with the photocell depended greatly on the pH value of the anolyte. Photocells containing an anolyte of pH 12 led to the formation of methanol in the cathode compartment, and oxygen gas evolved at the photoanode with a high current efficiency. In photocells in which the pH value of the anolyte was smaller than 11, however, CO2 was reduced only when an external bias was present. 相似文献
Highly aligned polyacetylene films are synthesized by three different methods in which nematic liquid crystals are used as an ordered matrix solvent: Method 1, polymerization of acetylene is carried out in a quiescent nematic solution in which a Ti(OBu)4-AlEt3 Ziegler-Natta catalyst is dissolved homogeneously; Method 2, macroscopic alignment is attained by gravity flow of the nematic liquid crystal-catalyst system; and Method 3, the nematic liquid crystal-catalyst solution is aligned under a magnetic field. Characterization of these films is carried out through SEM observation and measurements of polarized visible and infrared absorption spectra. Results indicate that as-prepared films have highly aligned fibrils. Upon doping by I2 and AsF5, these films exhibit high electrical condactivity of the order of 104 S/cm. 相似文献
Let A be a superelliptic differential operator of order 2m introduced by E.B. Davies [E.B. Davies, Uniformly elliptic operators with measurable coefficients, J. Funct. Anal. 132 (1995) 141-169]. In the case of 2m>N, he obtained the upper Gaussian bound of the integral kernel representing (e−zA)z∈C+ and the estimates of the Lp-operator norm of the semigroup for all p∈[1,∞). The purpose of the present paper is to show that −i(A+k) (for some constant k>0) generates an integrated semigroup on Lα,p (weighted Lp space) and lp(Lα,q). To prove this we need norm estimates of (e−zA)z∈C+ on each of these spaces. Also we get another norm estimate of (e−zA)z∈C+ on Lp when 2m>N without using the integral kernel. This norm estimate is better than that in [E.B. Davies, Uniformly elliptic operators with measurable coefficients, J. Funct. Anal. 132 (1995) 141-169] and gives a better “times of the integration” of the integrated semigroup. 相似文献
The efficient formation of low polydispersity core cross‐linked star (CCS) polymers via controlled/living radical polymerization (LRP) and the arm‐first approach was found to be dependant on the mediating catalyst system. The Ru catalyst, Ru(Ind)Cl(PPh3)2 Cat. 1 , and tertiary amine co‐catalyst were used to synthesize highly living poly(methyl methacrylate) (PMMA) macroinitiators, which were then linked together with ethylene glycol dimethacrylate (EGDMA) to form PMMAarmPEGDMAcore CCS polymers. The quantitative and near‐quantitative synthesis of CCS polymers were observed for low to moderate molecular weight macroinitiators ( = 8 and 20 kDa), respectively. Lower conversions were observed for high‐molecular weight macroinitiators ( ≥ 60 kDa). Overall, an improvement of between 10 and 20% was observed when comparing the Cat. 1 system to a conventional Cu‐catalyzed system. This significant improvement in macroinitiator‐to‐star conversion is explained in the context of catalyst system selection and CCS polymer formation.