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Imposing a steady ionic current through an electrolyte results in the formation of salt concentration gradients that compromise battery performance. The limiting current is usually defined as the c...

Regioregular poly(3-hexylthiophene) (rr-P3HT) was employed as the supporting polymeric matrix to generate hybrid composite films by mixing with natural zeolites, ZnO, and TiO2. Several P3HT-based hybrid composite films were deposited by a convenient method, characterized, and applied to the photocatalytic degradation of rhodamine 6G (R6G). The photocatalytic activity of the hybrid composite films was analyzed by degradation of R6G solutions (blank) under UV radiation (365 nm) and sunlight. It was observed that the photocatalytic activity of the composite films was higher as compared to the neat films of P3HT. This behavior was attributed to the extended photoresponse of the coupled organic–inorganic semiconductor system, facilitating separation of photogenerated carriers due to the strong interfacial interaction. The highest proportion of decolorization ratio of R6G obtained was close to 100%, and it was observed for the composite films P3HT/TiO2/ZnO and P3HT/chabazite/TiO2/ZnO under UV irradiation. Under sunlight, 99% and 97% decolorization ratios were obtained for P3HT/TiO2 and P3HT/TiO2/ZnO composite films, respectively.

Recent advancements in organic field effect transistors have switched chemists’ focus from synthesizing libraries of organic semiconductors to a more targeted approach where chemical alterations are performed on known semiconductors to further improve electronic properties. Among successful semiconducting polymer candidates, copolymers based on diketopyrrolopyrrole-and thieno[3,2-b]thiophene [P(DPP-TT)] have been subjected to modifications on the diketopyrrolopyrrole unit by using flanking groups and side chain engineering. Thieno[3,2-b]thiophene moiety, however, has seen minimal modifications due to the limited number of modifying sites. Isoelectronic thieno[3,2-b]pyrrole could serve as an alternative since it is easily tunable via N-alkylation reactions. Therefore, for the first time, we report the replacement of the thieno[3,2-b]thiophene unit of P(DPP-TT) with thieno[3,2-b]pyrrole unit and its performance in p-channel field effect transistors. The copolymer exhibits linear characteristics to achieve a...

The incorporation of functional groups into the side chains of polythiophenes can improve the phase separation of polymer : nanoparticle hybrid solar cells (HSCs). Our results showed that by introducing 17 mol% thiol functionality in the polymer, the Jsc and Voc can be increased by twofold in polymer : CdSe quantum dot (QD) HSCs.

Three donor–acceptor copolymers P1, P2, and P3 with N,N′-dodecylpyromellitic diimide as the electron-acceptor unit with three diethynyl-substituted donor monomers: 1,4-diethynyl-2,5-bis(octyloxy)benzene, 2,7-diethynyl-9,9-dioctyl-9H-fluorene, and 3,3′-didodecyl-5,5′-diethynyl-2,2′-bithiophene have been synthesized by Sonogashira crosscoupling polymerization. The synthesized polymers showed deep highest occupied molecular orbital energy levels and larger band gaps (>2.5 eV). Polymers P1, P2, and P3 underwent fluorescence quenching with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), indicating the intermolecular photo-induced charge transfer between the donor polymers and the PCBM acceptor. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1617–1622

Ziegler–Natta catalysts have played a major role in industry for the polymerization of dienes and vinyl monomers. However, due to the deactivation of the catalyst, this system fails to polymerize polar vinyl monomers such as vinyl acetate, methyl methacrylate, and methyl acrylate. Herein, a catalytic system composed of NdCl3⋅3TEP/TIBA is reported, which promotes a quasi-living polymerization of dienes and is also active for the homopolymerization of polar vinyl monomers. Additionally, this catalytic system generates polymyrcene-b-polyisoprene and poly(myrcene)-b-poly(methyl methacrylate) diblock copolymers by sequential monomer addition. To encourage the replacement of petroleum-based polymers by environmentally benign biobased polymers, polymerization of β-myrcene is demonstrated with a catalytic activity of ≈106 kg polymer mol Nd−1 h−1.

There is growing interest in fluorinated electrolytes due to their high-voltage stability. We use full electrochemical characterization based on concentrated solution theory to investigate the underpinnings of conductivity and transference number in tetraglyme/LiTFSI mixtures (H4) and a fluorinated analog, C8-DMC, mixed with LiFSI (F4). Conductivity is significantly lower in F4 than in H4, and F4 exhibits negative cation transference numbers, while that of H4 is positive at most salt concentrations. By relating Stefan-Maxwell diffusion coefficients, which quantify ion-solvent and cation-anion frictional interactions, to conductivity and transference number, we determine that at high salt concentrations, the origin of differences in transference number is differences in anion-solvent interactions. We also define new Nernst-Einstein-like equations relating conductivity to Stefan-Maxwell diffusion coefficients. In H4 at moderate to high salt concentrations, we find that all molecular interactions must be included. However, we demonstrate another regime, in which conductivity is controlled by cation-anion interactions. The applicability of this assumption is quantified by a pre-factor, β + − , which is similar to the “ionicity” pre-factor that is often included in the Nernst-Einstein equation. In F4, β + − is unity at all salt concentrations, indicating that ionic conductivity is entirely controlled by the Stefan-Maxwell diffusion coefficient quantifying cation-anion frictional interactions.

SummaryThe nuclear receptor peroxisome-proliferation-activated receptor gamma (PPARγ), a transcriptional master regulator of glucose and lipid metabolism, inhibits the growth of several common cancers, including lung cancer. In this study, we show that the mechanism by which activation of PPARγ inhibits proliferation of lung cancer cells is based on metabolic changes. We found that treatment with the PPARγ agonist pioglitazone triggers a metabolic switch that inhibits pyruvate oxidation and reduces glutathione levels. These PPARγ-induced metabolic changes result in a marked increase of reactive oxygen species (ROS) levels that lead to rapid hypophosphorylation of retinoblastoma protein (RB) and cell-cycle arrest. The antiproliferative effect of PPARγ activation can be prevented by suppressing pyruvate dehydrogenase kinase 4 (PDK4) or β-oxidation of fatty acids in vitro and in vivo. Our proposed mechanism also suggests that metabolic changes can rapidly and directly inhibit cell-cycle progression of cancer cells by altering ROS levels.

Electrical energy is ubiquitous in the modern world, and in order to continue pushing boundaries on consumer wearables, electric vehicles, and grid storage, secondary lithium-based rechargeable batteries need to be enhanced. The performance of binary electrolytes is governed by the electrolyte thermodynamic factor and three transport properties: conductivity, salt diffusion coefficient, and transference number. Rigorous methods for measuring conductivity and the salt diffusion coefficient are well established in literature. NMR and the steady-state current method are often used to measure the transference number, but are predicated on the dilute solution assumption and do not fully consider the non-ideality of the electrolyte. Within this work, we elucidate a complete set of lithium-ion transport properties for mixtures of dimethyl carbonate terminated perfluorinated tetraethylene ether and lithium bis(fluorosulfonyl)imide (LiFSI). The steady-state current transference number is positive across all concentrations and decreases with salt concentration, while the NMR transference number is approximately 0.5 everywhere. In contrast, we find that the transference number using Newman’s concentrated solution theory is negative across all concentrations. We show that Newman’s concentrated solution theory allows for accurate potential and limiting current modeling of lithium half cells whereas the steady-state current transference number severely over-estimates the electrolyte’s limiting current. The disparity between the dilute solution theory measurements and that of Newman’s concentrated solution theory approach indicates the dominance of ion clustering. Figure 1

A polyisoprene-b-polystyrene-b-poly(3-hexylthiophene) triblock copolymer was synthesized by anionic coupling of living polyisoprene-b-polystyryl lithium with allyl-terminated poly(3-hexylthiophene). The triblock copolymer retained the opto-electronic properties and morphology found in the poly(3-hexylthiophene) homopolymer despite the insulating polyisoprene and polystyrene blocks, making it potentially useful as an elastomeric semiconducting material.

Synthesis and photovoltaic properties of two donor–acceptor polymers containing benzodithiophene with 3,3′,5-trihexylbithienyl substituents are reported. Benzo[c][1,2,5]thiadiazole and 5-hexylthieno[3,4-c]pyrrole-4,6-dione were used as acceptor building blocks for the synthesis of donor–acceptor polymers. The photovoltaic properties of the synthesized donor–acceptor polymers were investigated in bulk heterojunction solar cells with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) acceptor.

The synthesis and polymerization of fused-ring 1,7-didodecyl-1,7-dihydrothieno[3,2-b:4,5-b′]dipyrrole monomer are reported. The FeCl3-mediated oxidative polymerization and Stille coupling polymerization of the thienodipyrrole monomer were employed to generate homopolymers and an alternating copolymer with thiophene. The synthesized polymers have molecular weights ranging from 1600 to 6500 g mol−1 and display the absorption maxima at ≈355 nm.

Three semiconducting polymers containing benzodithiophene with decylphenylethynyl substituents have been synthesized for which the spacing between alkyl substituents has been systematically increased by introduction of thiophene and bithiophene units in the backbone of the polymer. As the spacing between the side chains increased, an increase of the weight ratio of polymer to fullerene acceptor was required for achieving the highest power conversion efficiency of bulk heterojunction solar cells. The spacing between the side chains of the polymers was estimated from DFT calculations. The TMAFM analysis of polymer PCBM blends showed that the smooth films exhibited the highest solar cell performance.

Poly{4,8-bis(4-decylphenylethynyl)benzo[1,2-b:4,5-b′]dithiophene} (P1) homopolymer and poly{4,8-bis(4-decylphenylethynyl)benzo[1,2-b:4,5-b′]dithiophene -alt-thiophene} (P2) alternating copolymer have been synthesized by Stille coupling polymerization. The field-effect mobilities of both polymers were measured on both untreated and silane-treated OFET devices. Various silanes were selected to allow an incremental increase in the hydrophobicity of the silicon dioxide dielectric. A direct correlation was observed between the hydrophobicity of the silicon dioxide dielectric surface and the enhancement of the field-effect mobilities. The highest mobilities for both polymers were measured on the OFET devices treated with heptadecafluoro-1,1,2,2-tetrahydro-decyl-1-trimethoxysilane (FS) which generated the most hydrophobic surface. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Poly(3-hexylthiophene)-b-poly(4-vinylpyridine) diblock copolymer was synthesized by RAFT polymerization of 4-vinyl pyridine using a trithiocarbonate-terminated poly(3-hexylthiophene) macro-RAFT agent. The optoelectronic properties and the morphology of the block copolymer blends with CdSe quantum dots were investigated. UV-vis and fluorescence experiments were performed to prove the charge transfer between CdSe and poly(3-hexylthiophene)-b-poly(4-vinylpyridine) diblock copolymer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Poly(3-hexylthiophene)-b-poly(γ-benzyl-L-glutamate) (P3HT-b-PBLG) rod-rod diblock copolymer was synthesized by a ring-opening polymerization of γ-benzyl-L-glutamate-N-carboxyanhydride using a benzylamine-terminated regioregular P3HT macroinitiator. The opto-electronic properties of the diblock copolymer have been investigated. The P3HT precursor and the P3HT-b-PBLG have similar UV-Vis spectra both in solution and solid state, indicating that the presence of PBLG block does not decrease the effective conjugation length of the semiconducting polythiophene segment. The copolymer displays solvatochromic behavior in THF/water mixtures. The morphology of the diblock copolymer depends upon the solvent used for film casting and annealing results in morphological changes for both films deposited from chloroform and trichlorobenzene.

Semiconducting polymers containing benzodithiophene with decyl phenylethynyl and hexadecyl phenylethynyl substituents have been synthesized by Stille coupling polymerization. The optoelectronic properties of the synthesized polymers have been investigated. The synthesized polymers were tested in bulk heterojunction solar cells.

The rapid development of heavy industry in Vietnam leads to the establishments of steel industry. Steel slag, a by-product of steelwork industry, under Vietnamese's law, was considered as a deleterious solid waste which needed to be processed and landfilled. However, this has changed recently, and steel slag is now seen as a normal or non-deleterious solid waste, and has been studied for reuse in the construction industry. In this study, steel slag was used, as a replacement for mineral aggregate, in hot mix asphalt. Two hot mix asphalt mixtures with an equivalent nominal aggregate size of 12.5 (C12.5) and 19 mm (C19) were produced using steel slag. In addition, one conventional hot mix asphalt mixture of C19 was produced using mineral aggregate for comparison purpose. Investigation in laboratory condition and trial sections was carried out on Marshall tests, surface roughness, skid resistance, and modulus of the pavement before and after applying a new surface course of hot mix asphalt. The study showed that all steel slag asphalt mixtures passed the Marshall stability and flow test requirements. The skid resistance of steel slag hot mix asphalt mixtures for the surface course satisfied the Vietnamese specification for asphalt. Moreover, the pavement sections with the surface course of steel slag hot mix asphalt showed a considerable higher modulus than that of the conventional one. Only the roughness of the surface course paved with C19 did not pass the requirement of the specification.

Quorum sensing, the ability of bacteria to sense their own population density through the synthesis and detection of small molecule signals, has received a great deal of attention in recent years. Acyl homoserine lactones (AHLs) are a major class of quorum sensing signaling molecules. In nature, some bacteria that do not synthesize AHLs themselves have developed the ability to degrade these compounds by cleaving the amide bond or the lactone ring. By inactivating this signal used by competing bacteria, the degrading microbe is believed to gain a competitive advantage. In this work we report that CYP102A1, a widely studied cytochrome P450 from Bacillus megaterium, is capable of very efficient oxidation of AHLs and their lactonolysis products acyl homoserines. The previously known substrates for this enzyme, fatty acids, can also be formed in nature by hydrolysis of the amide of AHLs, so CYP102A1 is capable of inactivating the active parent compound and the products of both known pathways for AHL inactivation observed in nature. AHL oxidation primarily takes place at the omega-1, omega-2, and omega-3 carbons of the acyl chain, similar to this enzyme's well-known activity on fatty acids. Acyl homoserines and their lactones are better substrates for CYP102A1 than fatty acids. Bioassay of the quorum sensing activity of oxidation products reveals that the subterminally hydroxylated AHLs exhibit quorum sensing activity, but are 18-fold less active than the parent compound. In vivo, B. megaterium inactivates AHLs by a CYP102A1 dependent mechanism that must involve additional components that further sequester or metabolize the products, eliminating their quorum sensing activity. Cytochrome P450 oxidation of AHLs represents an important new mechanism of quorum quenching.

The tricarboxylic acid cycle enzyme fumarate hydratase (FH) has been identified as a tumor suppressor in a subset of human renal cell carcinomas. Human FH-deficient cancer cells display high fumarate concentration and ROS levels along with activation of HIF-1. The underlying mechanisms by which FH loss increases ROS and HIF-1 are not fully understood. Here, we report that glutamine-dependent oxidative citric acid cycle metabolism is required to generate fumarate and increase ROS and HIF-1 levels. Accumulated fumarate directly bonds the antioxidant glutathione in vitro and in vivo to produce the metabolite succinated glutathione (GSF). GSF acts as an alternative substrate to glutathione reductase to decrease NADPH levels and enhance mitochondrial ROS and HIF-1 activation. Increased ROS also correlates with hypermethylation of histones in these cells. Thus, fumarate serves as a proto-oncometabolite by binding to glutathione which results in the accumulation of ROS.

Cytochrome P450s are a superfamily of heme containing enzymes that use molecular oxygen and electrons from reduced nicotinamide cofactors to monooxygenate organic substrates. The fatty acid hydroxylase P450BM-3 has been particularly widely studied due to its stability, high activity, similarity to mammalian P450s, and presence of a cytochrome P450 reductase domain that allows the enzyme to directly receive electrons from NADPH without a requirement for additional redox proteins. We previously characterized the substrate N-palmitoylglycine, which found extensive use in studies of P450BM-3 due to its high affinity, high turnover number, and increased solubility as compared to fatty acid substrates. Here, we report that even higher affinity substrates can be designed by acylation of other amino acids, resulting in P450BM-3 substrates with dissociation constants below 100 nM. N-Palmitoyl-L-leucine and N-palmitoyl-l-methionine were found to have the highest affinity, with dissociation constants of less than 8 nM and turnover numbers similar to palmitic acid and N-palmitoylglycine. The interactions of the amino acid side chains with a hydrophobic pocket near R47, as revealed by our crystal structure determination of N-palmitoyl-l-methionine bound to the heme domain of P450BM-3, appears to be responsible for increasing the affinity of substrates. The side chain of R47, previously shown to be important in interactions with negatively charged substrates, does not interact strongly with N-palmitoyl-l-methionine and is found positioned at the enzyme-solvent interface. These are the tightest binding substrates for P450BM-3 reported to date, and the affinity likely approaches the maximum attainable affinity for the binding of substrates of this size to P450BM-3.

Synthesis of polythiophenes with alkenyl side chains is reported for the first time. The alkenyl side chains are versatile functional groups, allowing facile chemical modification to generate novel materials with tunable opto-electronic properties. Poly(3-pentenylthiophene), poly(3-undecenylthiophene), poly(3-hexylthiophene-ran-3-pentenylthiophene) and poly(3-hexylthiophene-ran-3-undecenylthiophene) were synthesized by a nickel mediated cross-coupling polymerization. Poly(3-alkenylthiophene) homopolymers and random copolymers were prepared from 2-bromo-5-chlorozinc-3-alkenylthiophene monomers using Ni(dppp)Cl2 as catalyst. The field-effect mobilities and photovoltaic response in bulk heterojunction solar cells were measured for poly(3-hexylthiophene-ran-3-pentenylthiophene) and poly(3-hexylthiophene-ran-3-undecenylthiophene).

Topical beta-blocking agents have been associated with adverse central nervous system (CNS) effects, including depression, emotional lability, and sexual dysfunction. Two studies were done to determine if patients who develop CNS effects while using timolol maleate would improve with betaxolol hydrochloride. In one study, 18 patients with CNS symptoms during timolol therapy were switched to betaxolol. Sixteen of the 18 patients noted symptomatic improvement with betaxolol. The second study involved seven patients with CNS symptoms during timolol therapy who were entered into a double-masked cross-over study. In two patients CNS symptoms resolved with betaxolol; in three patients symptoms improved; and in one patient symptoms worsened with betaxolol. Although factors influencing beta-blocker activity in the CNS are not well understood, there may be some advantage to a selective agent.