Voltage transfer function synthesis using current conveyors

A synthesis procedure for generating current conveyor active filters is presented, and a novel network which realises the general 2nd-order voltage transfer function is given.<>     

Internal plasticization of poly(vinyl) chloride using glutamic acid as a branched linker to incorporate four plasticizers per anchor point

Internal plasticization of polyvinyl chloride (PVC) using thermal azide‐alkyne Huisgen dipolar cycloaddition between azidized PVC and electron‐poor acetylenediamides incorporating a branched glutamic acid linker resulted in incorporation of four plasticizing moieties per attachment point on the polymer chain. A systematic study incorporating either alkyl or polyethylene glycol esters provided materials with varying degrees of plasticization, with depressed T_g values ranging from ?1 °C to 62 °C. Three interesting trends were observed. First, T_g values of PVC bearing various internal plasticizers were shown to decrease with increasing chain length of the plasticizing ester. Second, branched internal plasticizers bearing triethylene glycol chains had lower T_g values compared to those with similar length long‐chain alkyl groups. Finally, thermogravimetric analysis of these internally plasticized PVC samples revealed that these branched internal plasticizers bearing alkyl chains are more thermally stable than similarity branched plasticizers bearing triethylene glycol units. These internal tetra‐plasticizers were synthesized and attached to PVC‐azide in three simple synthetic steps. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1821–1835     

Optical,Electrical, and Magnetic Studies of Organic Solar Cells Based on Low Bandgap Copolymer with Spin ½ Radical Additives

The charge photogeneration and recombination processes in organic photovoltaic solar cells based on blend of the low bandgap copolymer, PTB7 (fluorinated poly‐thienothiophene‐benzodithiophene) with C60‐PCBM using optical, electrical, and magnetic measurements in thin films and devices is studied. A variety of steady state optical and magneto‐optical techniques were employed, such as photoinduced absorption (PA), magneto‐PA, doping‐induced absorption, and PA‐detected magnetic resonance (PADMR); as well as picosecond time‐resolved PA. The charge polarons and triplet exciton dynamics in films of pristine PTB7, PTB7/fullerene donor–acceptor (D–A) blend is followed. It is found that a major loss mechanism that limits the power conversion efficiency (PCE) of PTB7‐based solar cell devices is the “back reaction” that leads to triplet exciton formation in the polymer donor from the photogenerated charge‐transfer excitons at the D–A interfaces. A method of suppressing this “back reaction” by adding spin½ radicals Galvinoxyl to the D–A blend is presented; this enhances the cell PCE by ≈30%. The same method is not effective for cells based on PTB7/C70‐PCBM blend, where high PCE is reached even without Galvinoxyl radical additives.     

Noise sensitivity of watershed segmentation for different connectivity: experimental study

Low-budget image acquisition devices can produce noisy images, degrading segmentation quality. The sensitivity of two basic neighbourhood definitions to noise in watershed segmentation is compared. The two neighbourhood definitions are the 4- and 8-connected neighbourhoods. A similarity of segmentation to the noiseless original is observed, while increasing the energy of random Gaussian noise added to the image. It is concluded that the 8-connected neighbourhood is more robust.     

Nitrile Metabolizing Enzymes in Biocatalysis and Biotransformation

Nitrile metabolizing enzymes, i.e., aldoxime dehydratase, hydroxynitrile lyase, nitrilase, nitrile hydratase, and amidase, are the key catalysts in carbon nitrogen triple bond anabolism and catabolism. Over the past several years, these enzymes have drawn considerable attention as prominent biocatalysts in academia and industries because of their wide applications. Research on various aspects of these biocatalysts, i.e., sources, screening, function, purification, molecular cloning, structure, and mechanisms, has been conducted, and bioprocesses at various scales have been designed for the synthesis of myriads of useful compounds. This review is focused on the potential of nitrile metabolizing enzymes in the production of commercially important fine chemicals such as nitriles, carboxylic acids, and amides. A number of opportunities and challenges of nitrile metabolizing enzymes in bioprocess development for the production of bulk and fine chemicals are discussed.     

Molecular design,synthesis, and magnetic characterization of poly(phenylacetylene) with pi-toporegulated pendant nitronyl nitroxide radicals as models for organic superpara- and ferromagnets

The present article describes the synthesis and magnetic properties of poly(phenylacetylene) ( 3 ) with pi-toporegulated pendant stable 4,4,5,5-tetramethylimidazolin-3-oxide-1-yloxyl radicals topologically participating in the pi-conjugated system of poly(phenylacetylene). Polyradical 3 was prepared by the condensation reaction of poly(p-ethynylbenzaldehyde) with 2,3-bis(hydroxylamino)-2,3-dimethylbutane followed by oxidation with lead dioxide. The spin concentration of 3 determined by the ESR spectroscopic method was 1.1 × 10²¹ spins/g. This value approximately corresponds to 0.5 unpaired electron spin per the repeating unit. A powder ESR spectrum of 3 gave a 100% Lorentzian single line showing spin-exchange narrowing. The vibrating sample magnetometer (VSM) measurement of 3 afforded a straight line with a positive slope, suggesting that 3 has predominant paramagnetic properties within an experimental error.     

Porous structure of activated carbons and tert-butylbenzene breakthrough dynamics

The structural and adsorptive characteristics of six activated carbons were studied by means of nitrogen and benzene adsorption and water desorption. Tert-butylbenzene (TBB) breakthrough dynamics was analyzed by using several integral equations solved with a regularization/singular-value decomposition procedure. TBB interaction with texturally different activated carbons with the presence of preadsorbed or adsorbed water under dynamic conditions was illustrated by the breakthrough plots handled with several models. The influence of the type of activated carbons, their pore size distributions, water vapor, and TBB flow rate on the breakthrough times (tb) and the dynamic capacity of the carbon beds has been explored with better results for a carbon sample possessing a maximal contribution of mesopores at half-width x>1.5 nm among the carbons studied (which also appears on benzene adsorption) and a major contribution of microporocity as VDS/Vp approximately 0.88 and SK/SBET approximately 0.15. Another adsorbent, which is characterized by a similar total porosity but a larger micropore volume, a smaller contribution of mesopores (SK/SBET approximately 0.08), greater total and miroporous specific surface areas, and greater intensity of the pore size distribution at x<1.5 nm, shows the second result in dynamic TBB retention.     

On right S-Noetherian rings and S-Noetherian modules

In this paper we study right S-Noetherian rings and modules, extending notions introduced by Anderson and Dumitrescu in commutative algebra to noncommutative rings. Two characterizations of right S-Noetherian rings are given in terms of completely prime right ideals and point annihilator sets. We also prove an existence result for completely prime point annihilators of certain S-Noetherian modules with the following consequence in commutative algebra: If a module M over a commutative ring is S-Noetherian with respect to a multiplicative set S that contains no zero-divisors for M, then M has an associated prime.     

A 1.0-GHz single-issue 64-bit powerPC integer processor

The organization and circuit design of a 1.0 GHz integer processor built in 0.25 μm CMOS technology are presented, a microarchitecture emphasizing parallel computation with a single late select per cycle, structured control logic implemented by read-only-memories and programmable logic arrays, and a delayed reset dynamic circuit style enabling complex functions to be implemented in a few levels of logic are among the key design choices described. A means for at-speed scan testing of this high-frequency processor by a low-speed tester is also presented     

A Glycosylated Cationic Block Poly(β-peptide) Reverses Intrinsic Antibiotic Resistance in All ESKAPE Gram-Negative Bacteria

Carbapenem-resistant Gram-negative bacteria (GNB) are heading the list of pathogens for which antibiotics are the most critically needed. Many antibiotics are either unable to penetrate the outer-membrane or are excluded by efflux mechanisms. Here, we report a cationic block β-peptide (PAS8-b-PDM12) that reverses intrinsic antibiotic resistance in GNB by two distinct mechanisms of action. PAS8-b-PDM12 does not only compromise the integrity of the bacterial outer-membrane, it also deactivates efflux pump systems by dissipating the transmembrane electrochemical potential. As a result, PAS8-b-PDM12 sensitizes carbapenem- and colistin-resistant GNB to multiple antibiotics in vitro and in vivo. The β-peptide allows the perfect alternation of cationic versus hydrophobic side chains, representing a significant improvement over previous antimicrobial α-peptides sensitizing agents. Together, our results indicate that it is technically possible for a single adjuvant to reverse innate antibiotic resistance in all pathogenic GNB of the ESKAPE group, including those resistant to last resort antibiotics.