Conserved quantities for a class of (1 + n)-dimensional linear evolution equation

A special type of (1 + n)-dimensional linear evolution equation is considered. A class of the equations generated by the Fokker-Planck equation becomes the subcase of the considered equation. Conserved vectors using the partial Lagrangian approach is derived in terms of the coefficients of the discussed equation. Derived results are used for the different models from different sciences. We also discuss the conservation laws of the heat equation on curved manifolds and in different coordinate systems. Potential systems are also obtained for some models. At last conclusion is given.     

Facile and green fabrication of polybenzoxazine-based composite anion-exchange membranes with a self-cross-linked structure

A new type of composite anion-exchange membrane is fabricated using benzoxazine (Bz) monomer and polytetrafluoroethylene (PTFE) via a green and facile method. Membrane fabrication is achieved via in situ ring-opening polymerization of Bz within the PTFE matrix, followed by quaternization and ion-exchange reactions. The quaternized PBz works as a self-cross-linked and anion conductive polymer. The synthesized membranes show improved conductivity (26 to 70 mS/cm) at a reasonable water uptake and a low swelling ratio; they also show improved alkaline stability for 150 h at 60 °C in 1 M KOH solution, the decrease in conductivity being only ca. 10%. Our method of AEM fabrication is advantageous over conventional ones due to facile process and the avoidance of chloro- or bromomethylation as well as the self-cross-linked structure; the resulting membranes show relatively good performance as compared with some of those obtained from conventional techniques.     

Monte Carlo simulation of the two-dimensional planar model

We present results for the two-dimensional planar model on the square lattice. We have developed a Monte Carlo routine which is more efficient than the single-spin-flip algorithms used previously. We report on the variation of the following quantities with temperature: specific heat, energy, magnetization, susceptibility, correlation function, helicity modulus, the density of vortex/ antivortex pairs, the average distance between a vortex and its nearest antivortex, and the average distance between a vortex/antivortex pair and the nearest pair. Our results are in excellent agreement with the reliable results reported in the literature and are in accord with the general features of the Kosterlitz-Thouless theory.     

Synthesis and In Vivo antitumor and antiviral activities of 2′-deoxyribofuranosyl and arabinofuranosyl nucleosides of certain purine-6-sulfenamides,sulfinamides and sulfonamides

2′-Deoxyribofuranosyl and arabinofuranosyl nucleosides of certain purine-6-sulfenamides, sulfinamides and sulfonamides have been prepared by sequential amination and controlled oxidation of the corresponding 6-thiopurine nucleosides, and evaluated for antiviral and antitumor activities in mice. Amination of 2′-deoxy-6-thioinosine ( 4a ) and 9-β-D-arabinofuranosyl-6-thiopurine ( 4c ) with chloramine solution gave the corresponding 6-sulfenamides 5a and 5c , respectively, which on selective oxidation with 3-chloroperoxybenzoic acid (MCPBA) gave diastereomeric 9-(2-deoxy-β-D-erythro-pentofuranosyl)purine-6-sulfinamide ( 6a ) and 9-β-D-arabinofuranosylpurine-6-sulfinamide ( 6c ), respectively. However, oxidation of 5a and 5c with excess of MCPBA gave the corresponding 6-sulfonamide derivatives 7a and 7c , respectively. Similar amination of 2′-deoxy-6-thioguanosine ( 4b ), ara-6-thioguanine ( 4d ) and α-2′-deoxy-6-thioguanosine ( 8 ) gave the respective 6-sulfenamide derivatives 5b, 5d and 9 . Controlled oxidation of 5b, 5d and 9 gave (R,S)-2-amino-9-(2-deoxy-β-D-erythro-pentofuranosyl)purine-6-sulfinamide ( 6b ), (R,S)-2-amino-9-β-D-arabinofuranosylpurine-6-sulfinamide ( 6d ) and the α-anomer of ( 6b) (10 ), respectively. The diastereomeric mixture of (R,S )-10 was partially resolved and the structure of S -10 was assigned by single-crystal X-ray diffraction analysis. Oxidation of 5b, 5d and 9 with excess of MCPBA afforded the respective 6-sulfonamide derivatives 7b, 7d and 11 . Nucleosides 5c and 7c were significantly active against Friend leukemia virus in mice, whereas 6c was somewhat less active. Of the 20 nucleosides evaluated, 12 exhibited biologically significant anti-L1210 activity in mice. Nucleosides 6b and 7a at 173 mg/kg/day × 1 showed a T/C of 153, whereas 7d at 800 mg/kg/day × 1 showed a T/C of 153 against L1210 leukemia. The α-nucleoside 9 at 480 mg/kg/day × 1 gave a T/C of 172. A single treatment with 6b, 7a, 7d and 9 reduced the body burdens of viable L1210 cells by more than 99.2%. The antileukemic activity of these novel nucleosides tended to parallel solubility.     

Multielemental determination in water by neutron activation analysis

Instrumental neutron activation analysis (INAA) technique has been applied to a water sample to determine the elemental concentrations. The sample was irradiated at a neutron flux of 1.2·10¹² n·cm^–2·s^–1 for two different periods followed by counting at three different decay times, using two coaxial type high-resolution Ge(Li) detectors. The dominant elements detected in the water sample are Ca, Cl, Na, Mg, and K present in levels while Co, I, Mn, Sm, and Sb are present in smaller amounts approximately on the average 0.01 ppm. Only traces of other elements such as rare-earth elements, Ag, As, Ba, Cu, Cd, Fe, Sr, W, Zn, seem to be present in the water samples.     

The sorption of divalent metal ions on AlPO4

The sorption of Cu(2+), Pb(2+), Ni(2+), and Cd(2+) ions on the aluminum(III) phosphate was observed to increase with increases in the concentration, temperature, and pH of the system. The apparent dissociation (pK(a)), binding (pK(b)) and exchange (pK(ex)) constants of aluminum(III) phosphate were evaluated and found to be dependent upon the temperature and nature of the metal cations. The values of the dissociation constants (pK(a)) followed the order Pb(2+)相似文献   

Automated statistical experimental design approach for rapid separation of coenzyme Q10 and identification of its biotechnological process related impurities using UHPLC and UHPLC–APCI‐MS

A novel ultra high performance liquid chromatography method development strategy was ameliorated by applying quality by design approach. The developed systematic approach was divided into five steps (i) Analytical Target Profile, (ii) Critical Quality Attributes, (iii) Risk Assessments of Critical parameters using design of experiments (screening and optimization phases), (iv) Generation of design space, and (v) Process Capability Analysis (Cp) for robustness study using Monte Carlo simulation. The complete quality‐by‐design‐based method development was made automated and expedited by employing sub‐2 μm particles column with an ultra high performance liquid chromatography system. Successful chromatographic separation of the Coenzyme Q10 from its biotechnological process related impurities was achieved on a Waters Acquity phenyl hexyl (100 mm × 2.1 mm, 1.7 μm) column with gradient elution of 10 mM ammonium acetate buffer (pH 4.0) and a mixture of acetonitrile/2‐propanol (1:1) as the mobile phase. Through this study, fast and organized method development workflow was developed and robustness of the method was also demonstrated. The method was validated for specificity, linearity, accuracy, precision, and robustness in compliance to the International Conference on Harmonization, Q2 (R1) guidelines. The impurities were identified by atmospheric pressure chemical ionization‐mass spectrometry technique. Further, the in silico toxicity of impurities was analyzed using TOPKAT and DEREK software.