On the spectral norms of Cauchy–Toeplitz and Cauchy–Hankel matrices

In this study, we have found upper and lower bounds for the spectral norm of Cauchy–Toeplitz and Cauchy–Hankel matrices in the forms T_n=[1/(a+(i−j)b)]ⁿ_i,j=1, H_n=[1/(a+(i+j)b)]ⁿ_i,j=1.     

Novel fluorescent chemosensor for anions via modulation of oxidative PET: a remarkable 25-fold enhancement of emission

The fluorescence emission intensity of the 1:1 Zn(II) complex of a doubly boradiazaindacene (BODIPY) substituted bipyridyl ligand is highly sensitive to anion coordination to the metal center. Oxidative PET, which is responsible for the quenching of the fluorescence in the complex is effectively inhibited by anion coordination, leading to a 25-fold enhancement of the emission intensity.     

5—Br—PNPFF与镍（Ⅱ）的显色反应及其分析应用

研究了新试剂1-(5’-溴-2’-吡啶基)-5-(4’-硝基苯基)-3-(2’-呋喃基)甲■(5-Br-PNPFF)与镍(Ⅲ)的显色反应条件。在吐温-80存在下,pH5.0的邻苯二甲酸氢钾-氢氧化钠缓冲介质中,镍(Ⅲ)与5-Br-PNPFF形成1:2的深绿色配合物,其最大吸收峰在7 10nm处,ε_(710)=4.89×10~4 L/mol.cm~(-1)。选择性好,镍含量在0～300μg/L范围内符合比尔定律。用所拟方法测定钢铁中的微量镍,结果满意。     

离子液体作为溶剂/催化剂用于卤代烃对胺的选择性烷基化反应

在三乙胺存在下,在离子液体([bmim]I和[bmim]PF6)中进行了各种卤代烃对胺类化合物中氨基的选择性烷基化反应.反应在相对温和的条件下进行,转化率和选择性优异.离子液体可以回收并重复使用.     

Immobilization of Invertase in a Novel Proton Conducting Poly(vinylphosphonic acid) – poly(1-vinylimidazole) Network

A novel proton conducting polymer blend was prepared by mixing poly(vinylphosphonic acid) (PVPA) with poly(1-vinylimidazole) (PVI) at various stoichiometric ratios via changing molar ratio of monomer repeating unit to achieve the highest protonation. The polymer network having the most suitable stoichiometric ratio for substantial proton conductivity was prepared and characterized by FT-IR spectroscopy and proton conductivity measurements. The network was used for immobilization of invertase and some important kinetic parameters such as the maximum reaction rate (V_max) and Michaelis-Menten constant (K_m) were investigated for the immobilized invertase. Additionally, optimum temperature and pH were determined to acquire the best conditions for the highest enzyme activity. Operational stability of the entrapped enzyme was also examined. The results reveal that the most stable and highly proton conducting polymer network may play a pioneer role in the biosensors applications as given by FT-IR, elemental analysis, impedance spectroscopy and storage stability experiments.     

Highly Flexible and Tailorable Cobalt-Doped Cross-Linked Polyacrylamide-Based Electrolytes for Use in High-Performance Supercapacitors

A novel hydrogel polymer electrolyte was prepared by incorporation of 1,4-butanediol diglycidyl ether (BG) to cross-linked polyacrylamide (PAM). The electrolyte (PAMBG) was modified with cobalt (II) sulfate with various doping ratios (PAMBGCoX) to increase the capacitance by increasing faradaic reactions. The supercapacitor device assembly was performed by using active carbon (AC) electrodes and hydrogel polymer electrolytes. The specific capacitance of the PAMBGCo5 device indicated 130 F g⁻¹, which is at least a seven-fold improvement due to the insertion of Co as a redox component. The electrolyte device, PAMBGCo5, displays superior performance having an energy density of 38 Wh kg⁻¹ at a power density of 500 W kg⁻¹. Additionally, with the same hydrogel, the device performed 10,000 galvanostatic charge-discharge cycles via retaining 91% of the initial capacitance. A cost-effective electrolyte, PAMBGCo5, was tested in a carbon-based supercapacitor under bent and twisted conditions at various angles, confirming the robustness of the device.     

Essential oil composition, antimicrobial and cytotoxic activities of two endemic Stachys cretica subspecies (Lamiaceae) from Turkey

The chemical compositions of the water-distilled essential oil of Stachys cretica ssp. lesbiaca Rech. fil. and S. cretica ssp. trapezuntica Rech. fil. were determined by GC and GC-MS. Altogether 63 compounds were identified. The sesquiterpene hydrocarbon, germacrene D (20.3% and 12.9% respectively) was the main component identified in both oils. Furthermore, ethanol, light petroleum, dichloromethane, ethyl acetate and n-butanol extracts prepared from the aerial parts of the plants were tested for their antimicrobial activities against six bacterial strains and the yeast Candida albicans. The extracts exhibited no antibacterial activity, but the light petroleum and n-butanolic fractions showed low antifungal activities. Crude ethanolic extracts of the two subspecies were tested for their ability to inhibit the growth of HL-60 and Ishikawa human tumor cell lines. The IC50 values were 100 microg/mL for the HL-60 cell line and 200 microg/mL for the Ishikawa cell line.     

Synthesis of Symmetrical Multichromophoric Bodipy Dyes and Their Facile Transformation into Energy Transfer Cassettes

Multichromophoric boron‐dipyrromethene (Bodipy) dyes synthesized on phenylene‐ethynylene platforms have been be converted to energy transfer cassettes in a one‐step chemical transformation. Excitation energy transfer processes in these highly symmetrical derivatives were studied in detail, including time‐resolved fluorescence spectroscopy techniques. Excitation spectra and the emission lifetimes suggest efficient energy transfer between the donor and acceptor chromophore. These novel energy transfer cassettes, while highlighting a short‐cut approach to similar energy transfer systems, could be useful as large pseudo‐Stokes shift multichromophoric dyes with potential applications in diverse applications.