Synthesis and Cytotoxicity Evaluation of Certain α‐Methylidene‐ γ‐butyrolactones Bearing Coumarin,Flavone, Xanthone,Carbazole, and Dibenzofuran Moieties

The cytotoxicities of α‐methylidene‐γ‐butyrolactones, which are linked to coumarins (see 15 and 16 ) and to potential DNA‐intercalating carriers such as flavones, xanthones, carbazole, and dibenzofuran (see 9a – e , 10a – e , 11 , and 12 ), were studied. These compounds were synthesized via alkylation of their hydroxy precursors followed by a Reformatsky‐type condensation (Scheme). These α‐methylidene‐γ‐butyralactones were evaluated in vitro against 60 human tumor cell lines derived from nine cancer cell types and demonstrated a strong growth‐inhibitory activity against leukemia cancer cells (Tables 1 and 2). For flavone‐ and xanthone‐containing α‐methylidene‐γ‐butyrolactones 9a – e and 10a – e , respectively, the overall potency (mean value) decreased on introduction of an electron‐withdrawing substituent at the γ‐phenyl substituent and increased with an electron‐donating substituent. Comparing the different chromophores established the following order of decreasing potency (log GI₅₀): dibenzofuran ( 12 , −6.17) > flavone ( 9a , −5.96) > carbazole ( 11 , −5.80) and xanthone ( 10a , −5.77) > coumarin ( 15 , −5.60; 16 , −5.65). Among them, the dibenzofuran derivative 12 showed not only strong inhibitory activities against leukemia cancer cell lines with an average log GI₅₀ value of −7.22, but also good inhibitory activities against colon, melanoma, and breast cancer cells with average log GI₅₀ values of −6.23, −6.31, and −6.39, respectively.     

Highly selective multilayer polymer thin films for CO2/N2 separation

Multilayer thin films of poly(ethylene oxide) (PEO) and poly(methacrylic acid) (PMAA), deposited via layer‐by‐layer (LbL) assembly from aqueous solutions, are investigated for CO₂/N₂ separation. Eight and ten bilayer (217 and 389 nm thick, respectively) PEO/PMAA thin films deposited on a 25 μm polystyrene substrate exhibit CO₂/N₂ selectivities of 142 and 136, respectively. These are the highest reported to‐date for this gas pair separation using a homogeneous polymer film. While further work remains to improve CO₂ permeability, these results indicate the potential of LbL assemblies as standalone CO₂ separation membranes for low‐flux/high‐purity applications, or as part of a composite and/or mixed‐matrix membrane for high‐flux applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1730–1737     

Anion‐ and Solvent‐Induced Assembly and Reversible Structural Transformation of d10‐Metal Coordination Architectures Containing N‐(4‐(4‐Aminophenyloxy)phenyl)isonicotinamide

We set out studies on anion‐ and solvent‐induced assembly based on the ligand N‐(4‐(4‐aminophenyloxy)phenyl)isonicotinamide (papoa), which is synthesized to show a bent and flexible backbone. Reactions of papoa with ZnX₂ (X=Cl, Br, and I) gave the dinuclear macrocycles ([ZnX₂(papoa)]₂; X=Cl ( 1 a ), Br ( 2 a ), I ( 3 )), the structure of which was determined by X‐ray diffraction. Notably, the less bulky Cl and Br compounds afforded the coordinated imine in acetone (i.e., [ZnX₂(papoi)]₂, papoi=N‐(4‐(4‐(propan‐2‐ylideneamino)phenoxy)phenyl)isonicotinamide; X=Cl ( 1 b ), Br ( 2 b )), whereas the iodine one only gave the coordinated amine compound 3 under the same reaction condition. In fact, the coordinated imine can return to the amine analogue upon exposure to air or in DMSO, which has been monitored by ¹H NMR spectroscopy and powder X‐ray diffraction. Both the dinuclear [Zn(papoa)(NO₃)₂]₂ ( 4 a ) and the 1D [Zn(papoa)₂(NO₃)₂]_n ( 4 b ) were formed from the reaction of Zn(NO₃)₂ and papoa in mixed solvents with acetone and acetonitrile, respectively. In addition, Cd(ClO₄)₂ can react with papoa to give the 1D framework {[Cd(papoa)₂(CH₃CN)₂](ClO₄)₂}_n ( 5 a ) and the 2D framework [Cd(papoa)₂(ClO₄)₂]_n ( 5 b ), depending on the solvent used, that is, MeOH and CH₃CN, respectively. Importantly, the 1D framework with axially coordinated CH₃CN molecules and the 2D framework with axially coordinated ClO₄^? ions can be interconverted by heating and grinding in the presence of CH₃CN, respectively. Such a reversible structural transformation process was proven by PXRD studies.     

广义Goppa码最小距离下限的扩张及其译码

本文建立了由Lagrange插值公式决定的广义Goppa码最小距离下限扩张的一般定理,它包括了BCH码、广义BCH码和修改RS码的子域子码最小距离下限扩张结果,并对这些结果进行了改进,使其适用性更强.另外,本文还建立了用解线性方程组的方法实现最小距离下限扩张了的广义Goppa码的译码.广义Goppa码是目前较大的一种分组纠错码.因而,本文的结果可应用于现有的所有分组纠错码.     

Pulsed microwave plasma etching of polymers in oxygen and nitrogenfor microelectronic applications

Gaseous plasma generated by a half-wave rectified power supply are characterized and applied to the etching of photoresist and polymide in oxygen, dry air, or air. Activation energies of 8.6 kcal/mole and 10.9 kcal/mole are calculated for oxygen plasma etching of photoresist and polyimide, respectively. An average power of 625 W at 2.45 GHz is supplied by a magnetron through a rectangular waveguide to a 51-mm diameter quartz tube generating pulsed plasmas in oxygen and nitrogen at pressures between 0.1 torr and 10 torr with a repetitive rate of 60 Hz. The plasmas are studied by a double Langmuir probe and an optical emission spectrometer. Polymers placed in the downstream of the plasma are etched at high rates, especially when external heating is applied to raise the sample temperature. The characteristics of the plasmas and the application to the fast etching of polymers are discussed     

13C NMR Substituent Parameters of Dithioacetal Groups in Benzene Derivatives. The σp+ Values of Cyclic Dithioacetals

The ¹³C NMR spectra of forty-six cyclic dithioacetals and their derivatives have been studied. A set of shift parameters was established for each of these heterocycles as substituent. Based on the Hammett type correlation for substituted benzenes, the σ_P ⁺values of cyclic dithioacetal groups have been determined.     

Oligonucleotide-stabilized Ag nanocluster fluorophores

Single-stranded oligonucleotides stabilize highly fluorescent Ag nanoclusters, with emission colors tunable via DNA sequence. We utilized DNA microarrays to optimize these scaffold sequences for creating nearly spectrally pure Ag nanocluster fluorophores that are highly photostable and exhibit great buffer stability. Five different nanocluster emitters have been created with tunable emission from the blue to the near-IR and excellent photophysical properties. Ensemble and single molecule fluorescence studies show that oligonucleotide encapsulated Ag nanoclusters exhibit significantly greater photostability and higher emission rates than commonly used cyanine dyes.     

Optical Resolution of 5‐Oxo‐1‐Phenyl‐Pyrazolidine‐3‐Carboxylic Acid as a New Organocatalyst for Organic Reactions

Optical resolution of racemic 5‐oxo‐1‐phenyl‐pyrazolidine‐3‐carboxylic acid 2 with L‐amino acid methyl ester via the diastereomers formation was investigated. Treatment of racemic 5‐oxo‐1‐phenyl‐pyrazolidine‐3‐carboxylic acid 2 with L‐valine methyl ester gave diastereomers with a total yield of 86%. The diastereomeric dipeptides can be easily separated by flash column chromatography. Acidic cleavage of the derived diastereomers gave both the optically pure (+)‐(R)‐ and (‐)‐(S)‐5‐oxo‐1‐phenyl‐pyrazolidine‐3‐carboxylic acid ((+)‐(R)‐ 2 and (‐)‐(S)‐ 2 ) with a total yield of 94% and 95%, respectively.     

Single-walled carbon nanotubes displaying multivalent ligands for capturing pathogens

A single-walled carbon nanotube was exploited for its semi-flexible pseudo-one-dimensional nanostructure as a unique scaffold to display multivalent carbohydrate ligands, with a specific demonstration showing that galactosylated carbon nanotubes were effective in the capturing of pathogenic Escherichia coli in solution.