Synthesis and characterization of high refractive index polyimides derived from 2,5‐Bis(4‐Aminophenylenesulfanyl)‐3,4‐Ethylenedithiothiophene and aromatic dianhydrides

The authors describe the synthesis and characterization of the polyimide (PI) series containing a 2,5‐bis(4‐aminophenylenesulfanyl)‐3,4‐ethylenedithiothiophene (APSEDTT) moiety in their main chain. The APSEDTT monomer with high sulfur content was prepared and polymerized with several aromatic dianhydrides such as 4,4′‐[p‐thio bis(phenylenesulfanyl)]diphthalic anhydride (3SDEA), 4,4′‐biphthalic anhydride (BPDA), and 4,4′‐oxydiphthalic anhydride (ODPA) by the traditional two‐step polycondensation procedure. All PIs exhibited high transparency, higher than 75% at 550 nm for a thickness of about 20 μm and good thermal properties such as thermal decomposition temperatures (T_10%) in the range of 409–521 °C. In addition, the PIs have extraordinarily excellent optical properties in refractive index and birefringence as originally designed. In particular, the PI derived from APSEDTT and 3SDEA showed a high refractive index (1.7586), and a low birefringence (0.0087) because of their very high sulfur content (27.7%). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 944–950     

Feasibility study of k0-INAA at the ITU TRIGA Mark II research reactor,Turkey

In this study, the effect of contact time, pH, competitive cations and equilibrium study of adsorption on Slovak illite/smectite Dolná Ves was investigated. The sorption processes was studied using batch techniques under aerobic conditions with radioisotope indication using ⁶³Ni as a radiotracer. Studied material has proved to be as promising candidate for practically used as a barrier against the spread of undesirable substances in the environment landfill as insulating material of toxic and hazardous waste.     

Spiro(phosphoamidite) ligand (SIPHOS)/Cu(OTf)2-catalyzed highly regio- and stereo-selective hydroborations of internal alkynes with diborane in water

The highly regio- and stereoselective hydroborations of unactivated internal alkynes with diboron compound catalyzed by Cu(OTf)₂ with spiro(phosphoamidite) as ligand in the presence of Cs₂CO₃ in water was developed. This protocol was applied efficiently in the aqueous synthesis of multi-substituted vinylboranes.     

银耳状Fe-N-C复合催化剂的制备及催化氧还原性能研究

以无机铁盐和邻苯二胺为基础原料,经铁基螯合前驱体热解反应,制备出Fe-N-C复合催化剂.经扫描电镜观察,带有折褶的碳微纳米片相互交迭,形成银耳状的三维自支撑结构.氮气吸脱附测试表明此结构富含微孔和介孔,比表面积可达290 m2/g.通过X射线衍射(XRD)确证石墨化C和多晶Fe3C作为催化剂主相存在, X射线光电子能谱(XPS)进一步揭示N原子主要以石墨N和吡啶N形式掺杂到C骨架中.电化学测试表明银耳状Fe-N-C复合催化剂在碱性条件下催化氧还原反应为四电子过程,其催化活性可媲美商业Pt/C催化剂.经过2000次氧还原测试后,催化极限电流衰减小于5%,并且半波电势仅负移5 mV(商业Pt/C催化剂负移35 mV),表现出优异的氧还原催化稳定性.     

Two-track virtual screening approach to identify both competitive and allosteric inhibitors of human small C-terminal domain phosphatase 1

Despite a wealth of persuasive evidence for the involvement of human small C-terminal domain phosphatase 1 (Scp1) in the impairment of neuronal differentiation and in Huntington’s disease, small-molecule inhibitors of Scp1 have been rarely reported so far. This study aims to the discovery of both competitive and allosteric Scp1 inhibitors through the two-track virtual screening procedure. By virtue of the improvement of the scoring function by implementing a new molecular solvation energy term and by reoptimizing the atomic charges for the active-site Mg²⁺ ion cluster, we have been able to identify three allosteric and five competitive Scp1 inhibitors with low-micromolar inhibitory activity. Consistent with the results of kinetic studies on the inhibitory mechanisms, the allosteric inhibitors appear to be accommodated in the peripheral binding pocket through the hydrophobic interactions with the nonpolar residues whereas the competitive ones bind tightly in the active site with a direct coordination to the central Mg²⁺ ion. Some structural modifications to improve the biochemical potency of the newly identified inhibitors are proposed based on the binding modes estimated with docking simulations.     

Zirconia—A stationary phase capable of the separation of polar markers of myocardial metabolism in hydrophilic interaction chromatography

Creatine, phosphocreatine, and adenine nucleotides are highly polar markers of myocardial metabolism that are poorly retained on RP silica sorbents. Zirconia represents an alternative material to silica with high promise to be used in hydrophilic interaction chromatography (HILIC). This study describes a first systematic investigation of the ability of ZrO₂ to separate creatine, phosphocreatine, adenosine 5′‐monophosphate, adenosine 5′‐diphosphate, and adenosine 5′‐triphosphate and compares the results with those obtained on TiO₂. All analytes showed a HILIC‐like retention pattern when mobile phases of different strengths were tested. Stronger retention and better column performance were achieved in organic‐rich mobile phases as compared to aqueous conditions, where poor retention and insufficient column performance were observed. The effect of mobile phase pH and ionic strength was evaluated as well. The analysis of myocardial tissue demonstrated that all compounds were separated in a relevant biological material and thus proved ZrO₂ as a promising phase for HILIC of biological samples that deserves further investigation.     

Electropolymerized Diphenylamine on Functionalized Multiwalled Carbon Nanotube Composite Film and Its Application to Develop a Multifunctional Biosensor

Diphenylamine (DPA) monomers have been electropolymerized on the amino‐functionalized multiwalled carbon nanotube (AFCNT) composite film modified glassy carbon electrode (GCE) by cyclic voltammetry (CV). The surface morphology of PDPA‐AFCNT was studied using field‐emission scanning electron microscopy (FE‐SEM). The interfacial electron transfer phenomenon at the modified electrode was studied using electrochemical impedance spectroscopy (EIS). The PDPA‐AFCNT/GCE represented a multifunctional sensor and showed good electrocatalytic behavior towards the oxidation of catechol and the reduction of hydrogen peroxide. Rotating‐disk electrode technique was applied to detect catechol with a sensitivity of 1360 µA mM^?1 cm^?2 and a detection limit of 0.01 mM. Amperometric determination of hydrogen peroxide at the PDPA‐AFCNT film modified electrode results in a linear range from 10 to 800 µM, a sensitivity of 487.1 µA mM^?1 cm^?2 and detection limit of 1 µM. These results show that the nano‐composite film modified electrode can be utilized to develop a multifunctional sensor.     

N-[1-(Benzotriazol-1-yl)alkyl]amides from N-acyl-α-amino acids or N-alkylamides

A variety of N-(1-methoxyalkyl)amides react with benzotriazole in the presence of PPh₃·HBF₄ and organic bases (Hünig's base, DBU or DABCO) or solid-state-supported bases (SiO₂-Pip or IRA-67) in CHCl₃ to give N-[1-(benzotriazol-1-yl)alkyl]amides in good yields. The most convenient and efficient procedure for obtaining N-[1-(benzotriazol-1-yl)alkyl]amides consists, however, of the addition of benzotriazole sodium salt to a solution of crude 1-(N-acylamino)alkyltriphenylphosphonium salt, obtained in situ from N-(1-methoxyalkyl)amides and PPh₃·HBF₄. A combination of these reactions with the recently described electrochemical decarboxylative α-methoxylation of N-acyl-α-amino acids in the presence of SiO₂-Pip enables an effective two-pot transformation of N-acyl-α-amino acids to N-[1-(benzotriazol-1-yl)alkyl]amides.     

CD133 and CD133‐regulated nucleophosmin linked to 5‐fluorouracil susceptibility in human colon cancer cell line SW620

Cancer stem cells (CSCs) are known to be resistant to conventional chemotherapy and radiotherapy. Specific CSC targeting and eradication is therefore a therapeutically important challenge. CD133 is a colorectal CSC marker with unknown function(s). Assessing proteomic changes induced by CD133 may provide clues not only to new CD133 functions but also to the chemotherapy and radiation susceptibility of colon cancer cells. To identify the proteins affected by CD133, CD133‐positive (CD133+), and CD133‐negative (CD133–) human colon cancer cells were obtained by cell sorting. Whole proteomes were profiled from SW620/CD133+ and SW620/CD133– cells and analyzed by 2D‐based proteome analysis. Nucleophosmin (NPM1) was identified as a protein regulated by CD133. CD133 protein level was not affected by NPM1, and an interaction between the two proteins was not observed. CD133 and NPM1 protein levels were positively correlated in 11 human colon cancer cell lines. The CD133+ subpopulation percentage or its value normalized against CD133 protein level was only linked to intrinsic susceptibility of human colon cancer cells to 5‐fluorouracil (5‐FU). However, either suppression of CD133 or NPM1 significantly increased 5‐FU susceptibility of SW620. The present study suggests that CD133‐regulated NPM1 protein level may provide a clue to novel CD133 function(s) linked to human colon cancer cell susceptibility to chemotherapy.     

Effects of extremely low frequency magnetic field on the antioxidant defense system in mouse brain: a chemiluminescence study

Among the putative mechanisms, by which extremely low frequency (ELF) magnetic field (MF) may affect biological systems is that of increasing free radical life span in organisms. To test this hypothesis, we investigated whether ELF (60 Hz) MF can modulate antioxidant system in mouse brain by detecting chemiluminescence and measuring superoxide dismutase (SOD) activity in homogenates of the organ. Compared to sham exposed control group, lucigenin-initiated chemiluminescence in exposed group was not significantly increased. However, lucigenin-amplified t-butyl hydroperoxide (TBHP)-initiated brain homogenates chemiluminescence, was significantly increased in mouse exposed to 60 Hz, MF, 12 G for 3 h compared to sham exposed group. We also measured SOD activity, that plays a critical role of the antioxidant defensive system in brain. In the group exposed to 60 Hz, MF, 12 G for 3 h, brain SOD activity was significantly increased. These results suggest that 60 Hz, MF could deteriorate antioxidant defensive system by reactive oxygen species (ROS), other than superoxide radicals. Further studies are needed to identify the kind of ROS generated by the exposure to 60 Hz, MF and elucidate how MF can affect biological system in connection with oxidative stress.