In this article we prove that an algebraic Lie algebra over an algebraically closed field of characteristic 0 is complete if its Borel subalgebras are complete. Thus the study on complete Lie algebras may somewhat be reduced to that on solvable complete ones. 相似文献
Enzyme activity in live cells is dynamically regulated by small‐molecule transmitters for maintaining normal physiological functions. A few probes have been devised to measure intracellular enzyme activities by fluorescent imaging, but the study of the regulation of enzyme activity via gasotransmitters in situ remains a long‐standing challenge. Herein, we report a three‐channel imaging correlation by a single dual‐reactive fluorescent probe to measure the dependence of phosphatase activity on the H2S level in cells. The two sites of the probe reactive to H2S and phosphatase individually produce blue and green fluorescent responses, respectively, and resonance energy transfer can be triggered by their coexistence. Fluorescent analysis based on the three‐channel imaging correlation shows that cells have an ideal level of H2S to promote phosphatase activity up to its maximum. Significantly, a slight deviation from this H2S level leads to a sharp decrease of phosphatase activity. The discovery further strengthens our understanding of the importance of H2S in cellular signaling and in various human diseases. 相似文献
We synthesise a novel poly(ionic liquid) (PIL) and develop a procedure that allows the phase transfer of graphene oxides (GO) from water to organic solvent, retaining graphene oxide liquid crystal (GOLC) phase in various organic solvents, especially non-polar organic solvents. PIL ([PEP-MIM]DBS) is exploited in this procedure as a noncovalent functional material that is capable of transporting GO from aqueous to non-polar organic phase. PILs can decorate GO noncovalently and keep GO nano-sheets exfoliated in solid-state PILs/GO hybrids, which can well redisperse in organic solvents without any agglomeration. This expands the number of known solvents which can support GOLC phase to dimethyl formamide, dimethyl sulfoxide, acetonitrile, tetrahydrofuran, and a number of other non-polar organic solvents, many of which were not known to afford GOLC phase prior to this report, such as dichloromethane, tetrachloromethane, dichloroethane and tetrachloroethane. 相似文献
In this research, the n-butyl palmitate was synthesized using the esterification reaction of the PA with n-butanol. The 1H nuclear magnetic resonance and Fourier transform infrared illustrated that the hydroxyl group and carboxyl group disappeared, and the ester bond appeared after the reaction, explaining that n-butyl palmitate was successfully fabricated. The differential scanning calorimetry indicated that the phase-transition temperature and latent heat are 12.6 °C and 127.1 J g?1, which was suited to use in low-temperature fields such as food, pharmaceutical, and biomedical. The thermogravimetric analysis suggested that it had great thermal stability during the phase change process. In addition, the thermal conductivity of the n-butyl palmitate was slightly higher than other fatty acid ester, and the 500 thermal cycles test results indicated that it had excellent thermal reliability. Therefore, the n-butyl palmitate is deduced to share great thermal energy storage ability in terms of latent heat thermal energy system applications.
On the basis of the coupled-mode theory, a detailed investigation of the optical spectral characteristics is presented for uniform tilted fiber gratings. Explicit expressions are derived for the spectral parameters of reflection and transmission spectra. Numerical simulations are carried on to show the dependences of grating spectral responses on the structural parameters, such as tilt angle, grating length, index modulation amplitude and polarization states. The effects of these parameters on shaping the grating spectra are discussed comprehensively. The physical mechanism and intuitive phase-matching vector model are provided to explain the unique behaviors of transmission loss spectra. The results are helpful for providing a better understanding of the spectral behavior of the tilted fiber grating. 相似文献
A novel tunable and reconfigurable microwave photonic filter based on two cascaded modulators and a dispersive medium is proposed, theoretically discussed and experimentally demonstrated. A single-wavelength LD and a modulator (either a Mach-Zehnder modulator or a phase modulator which can avoid the dc bias drift problem) are used to obtain a multi-wavelength optical source. By adjusting the modulation frequency and the bias voltage on the modulators, the wavelength spacing and the relative amplitude of the optical tones change, thus making the filter tunable and reconfigurable. The experimental results show that the proposed filters have good tunability and reconfigurability and the mainlobe-to-sidelobe ratio of around 25 dB is achieved. 相似文献