Analytical and Bioanalytical Chemistry - Appropriate sample preparation is pivotally important to obtain high-quality mass spectrometry imaging (MSI) data. Unlike mammalian tissues, preparation of... 相似文献
2 Abstract For the 2-D quasilinear wave equation(?_t~2-?_x)u+2∑ij=0g~(ij)(?u)?_(ij)u = 0 satisfying i,j=0 null condition or both null conditions, a blowup or global existence result has been shown by Alinhac. In this paper, we consider a more general 2-D quasilinear wave equation(?_t~2-?_x)_u+2∑ij=0g~(ij)(?u)?_(ij)u = 0 satisfying null conditions with small initial data and the coefficients i,j=0 depending simultaneously on u and ?u. Through construction of an approximate solution,combined with weighted energy integral method, a quasi-global or global existence solution are established by continuous induction. 相似文献
With the development of nano-powder technology, polymeric nano-materials are widely used in various industries, while not much research on their thermal decomposition and dust explosion characteristics has been conducted. The thermal behaviors and explosion characteristic parameters of the nano-polystyrene (nano-PS) with a typical particle size of 90 nm were studied by employing thermogravimetric analysis (TG), MIE-D 1.2 minimum ignition energy (MIE) test device, and 20-L spherical dust explosion test equipment. The results showed that the thermal decomposition of the nano-PS occurred in a two-step process which was different from the single process for conventional PS. Meanwhile, the reaction rate of the thermal decomposition for nano-PS increased with the heating rate. The TG and DTG curves shifted to the higher-temperature zone when the heating rate increased, and the initial temperature, final temperature, temperature at the maximum rate, and the maximum rate also increased. The sensitivity parameter of the minimum ignition energy of nano-PS varied as the dust concentration altered, and the most sensitive explosive concentration was about 200 g m−3. Also, nano-PS was proved to be quite sensitive to the electrostatic spark, as its calculated MIE value was as low as 11 mJ. For the severity parameters, the explosion pressure and its rising rate of nano-PS tended to increase at first and then decrease with the increase in dust concentrations. According to the risk classification standard, the explosion risk class of nano-PS was St2. The results were further extensively compared to other previous works. The results demonstrated both the higher explosion possibility and severity of nano-PS. This study could provide guidance for the safety management of nano-PS in its manufacture, storage, and handling process.
Littordial F (1), a novel meroterpenoid with an unique 6/8/9/4-tetracyclic nucleus, was isolated from the leaves of Psidium littorale. The structure of 1 was established by spectroscopic data, and its absolute configuration was confirmed by computational 13C NMR and optical rotation data. Compound 1 exhibited potential cytotoxic activities on A549, B16, and HepG-2 cell lines. A plausible biosynthetic pathway for littordial F was proposed. 相似文献
mTOR has become a promising target for many types of cancer like breast, lung and renal cell carcinoma. CoMFA, CoMSIA, Topomer CoMFA and HQSAR were performed on the series of 39 triazine morpholino derivatives. CoMFA analysis showed q2 value of 0.735, r2cv value of 0.722 and r2pred value of 0.769. CoMSIA analysis (SEHD) showed q2 value of 0.761, r2cv value of 0.775 and r2pred value of 0.651. Topomer CoMFA analysis showed q2 value of 0.693, r2 (conventional correlation coefficient) value of 0.940 and r2pred value of 0.720. HQSAR analysis showed q2,r2and r2pred values of 0.694, 0.920 and 0.750, respectively. HQSAR analysis with the combination of atomic number (A), bond type (B) and atomic connections showed q2 and r2 values of 0.655 and 0.891, respectively. Contour maps from all studies provided significant insights. Molecular docking studies with molecular dynamics simulations were carried out on the highly potent compound 36. Furthermore, four acridine derivatives were designed and docking results of these designed compounds showed the same interactions as that of the standard PI-103 which proved the efficiency of 3D-QSAR and MD/MS study. In future, this study might be useful prior to synthesis for the designing of novel mTOR inhibitors. 相似文献
Recent studies have shown impressive transport behaviors of water and ions within lamellar MXene membranes,which endows great promise in developing advanced separation application based high performance MXene membranes.However,most of the researches focused on modification of MXene nanoflakes and optimizing interlayer distance,leaving the impact of membrane fabrication process marginal.In this work,we studied the water flux of membranes made by vacuum filtration using delaminated MXene nanoflakes as the building-blocks.Our results show that the water permeability is extremely sensitive to the process,especially at the drying process,loading and deposit rate of nanoflakes(the feeding concentration).We find that the voids from less ordered stack rather than in-plane defects and interlayer galleries contribute to the large water permeability.The voids can be effectively avoided via deposition of MXene nanoflakes at a slow rate.Manipulating the stack of MXene nanoflakes during vacuum filtration and drying are critical for development of MXene membranes with desired performance for water permeation. 相似文献