Multichromic polymers based on pyrene clicked thienylpyrrole

In this study, the effect of pendant pyrene on the optical and electronic properties of poly(2,5‐dithienylpyrrole)s was studied. For this purpose a new pyrene coupled 2,5‐dithienylpyrrole derivative (SNS‐pyrene) was synthesized through click reaction. SNS‐pyrene was electrochemically polymerized and its electrochemical and optical properties were investigated by electrochemical and optical techniques. The polymer had a band gap of 3.36 eV and displayed light green to blue color variation upon oxidation in less than 2.48 s. Additionally, electrochemical copolymerization of SNS‐pyrene with 3,4‐ethylenedioxythiophene was achieved whilst a detailed investigation was performed on the effect of electrochemical polymerization conditions on the optoelectronic properties of the copolymers. Studies revealed that the copolymers exhibit multichromic reversible redox behavior with lower band gaps and shorter switching times than their parent polymer, P(SNS‐pyrene) © 2014 Society of Chemical Industry.     

Masking the Peroxidase-Like Activity of the Molybdenum Disulfide Nanozyme Enables Label-Free Lipase Detection

Two-dimensional MoS₂ nanoparticles (2D-nps) exhibit artificial enzyme properties that can be regulated at bio-nanointerfaces. We discovered that protein lipase is able to tune the peroxidase-like activity of MoS₂ 2D-nps, offering low-nanomolar, label-free detection and identification in samples with unknown identity. The inhibition of the peroxidase-like activity of the MoS₂ 2D-nps was demonstrated to be concentration dependent, and as low as 5 nm lipase was detected with this approach. The results were compared with those obtained with several other proteins that did not display any significant interference with the nanozyme behavior of the MoS₂ 2D-nps. This unique response of lipase was characterized and exploited for the successful identification of lipase in six unknown samples by using qualitative visual inspection and a quantitative statistical analysis method. The developed methodology in this approach is noteworthy for many aspects; MoS₂ 2D-nps are neither labeled with a signaling moiety nor modified with any ligands for signal readout. Only the intrinsic nanozyme activity of the MoS₂ 2D-nps is exploited for this detection approach. No analytical equipment is necessary for the visual detection of lipase. The synthesis of the water-soluble MoS₂ 2D-nps is low costing and can be performed in bulk scale. Exploring the properties of 2D-nps and their interactions with biological materials reveals highly interesting yet instrumental features that offer the development of novel bioanalytical approaches.     

Screening physicochemical,microbiological and bioactive properties of fruit vinegars produced from various raw materials

Food Science and Biotechnology - In the present study, variety of fruit vinegars were investigated in terms of their physicochemical, microbiological and bioactive properties. Total phenolic and...     

A two-dimensional material for high capacity supercapacitors: S-doped graphene

In this work, sulfur-doped graphene-coated electrodes are prepared by cyclic voltammetry in different potential ranges and different cycles (from 10 to 50) for selective modification of electrodes by different functional groups. The prepared electrodes are characterized by spectroscopic, microscopic and electrochemical methods. In scanning electron microscopic analysis, formation of graphene layers and their porous structure have been determined. Electrochemical impedance spectroscopic and cyclic voltammetric analyses are also used in electrochemical characterization of the electrodes. Then, the prepared sulfur-doped graphene-coated electrodes by using cyclic voltammetry in one-step and low cost are used as electrode materials of supercapacitor for the first time in the literature. Since the mesoporous structure of the electrodes prepared in lower potential ranges increases, specific capacitance of the electrodes increases from 74 to 1833 mF cm⁻² with 10 mA cm⁻² current density. This result shows that specific capacitances of prepared electrodes are higher than those of the electrodes prepared with metal-doped in the literature.     

Impact of non-normal random effects on inference by multiple imputation: A simulation assessment

Multivariate extensions of well-known linear mixed-effects models have been increasingly utilized in inference by multiple imputation in the analysis of multilevel incomplete data. The normality assumption for the underlying error terms and random effects plays a crucial role in simulating the posterior predictive distribution from which the multiple imputations are drawn. The plausibility of this normality assumption on the subject-specific random effects is assessed. Specifically, the performance of multiple imputation created under a multivariate linear mixed-effects model is investigated on a diverse set of incomplete data sets simulated under varying distributional characteristics. Under moderate amounts of missing data, the simulation study confirms that the underlying model leads to a well-calibrated procedure with negligible biases and actual coverage rates close to nominal rates in estimates of the regression coefficients. Estimation quality of the random-effect variance and association measures, however, are negatively affected from both the misspecification of the random-effect distribution and number of incompletely-observed variables. Some of the adverse impacts include lower coverage rates and increased biases.     

Fabrication and magnetoresistivit of ex-situ processed MgB<Subscript>2</Subscript>/Fe monofilament tapes without any intermediate annealing

We have fabricated MgB₂/Fe monofilament wires and tapes by a powder-in tube (PIT) technique, using an ex-situ process without any intermediate annealing. MgB₂/Fe monofilament tapes were annealed at 650–1,050°C for 60 min and 950°C for 30–240 min. We have investigated the effect of annealing temperatures and times on the formation of MgB₂ phase, activation energy, temperature dependence of irreversibility field H _irr(T) and upper critical field H _c2(T), transition temperature (T _c), lattice parameters (a and c), full width at half maximum, crystallinity, resistivity, residual resistivity ratio, active cross-sectional area fraction and critical current densities. We observed that the activation energies of the MgB₂/Fe monofilament samples increased with increasing annealing temperature up to 950°C and with increasing annealing time up to 60 min while it decreased with increasing magnetic field. For the MgB₂/Fe monofilament tape, the slope of the H _c2–T and H _irr–T curves decreased with increasing annealing temperature from 850 to 950°C as well as with increasing annealing time from 30 to 60 min. The transport and microstructure investigations show that T _c, J _c and microstructure properties are remarkably enhanced with increasing annealing temperature. The highest value of critical current density is obtained for the sample annealed at 950°C for 60 min. The J _c and T _c^offset values of the sample annealed at 950°C for 60 min were found to be 260.43 A/cm² at 20 and 38.1 K, respectively.     

Cooling slope casting to produce EN AW 6082 forging stock for manufacture of suspension components

The potential of cooling slope casting process to produce EN AW 6082 forging stock for the manufacture of EN AW 6082 suspension components was investigated. EN AW 6082 billets cast over a cooling plate offer a fine uniform structure that can be forged even without a separate homogenization treatment. This is made it possible by the limited superheat of the melt at the start of casting and the fractional solidification that occurs already on the cooling plate. Suspension parts forged from cast and homogenized billets with or without Cr all showed a uniform structure, and the hardness reached HV 110 after the standard artificial ageing treatment.