Surface characteristics of UV-irradiated polyurethane elastomers extended with α, ω-alkane diols

Polyurethane elastomers (PUEs) based on 4,4′-diphenylmethane diisocyanate (MDI), poly (?-caprolactone) (PCL) and extended with series of chain extender (CE) were synthesized via two step polymerization technique. The synthesized samples were irradiated for 50, 100 and 200 h in an UV exposure unit as such the spectral distribution of the light is good match for terrestrial solar radiation. The modifications in the chemical structures of the PU before and after irradiation were characterized using Fourier transform infrared (FT-IR) technique. The effect of irradiation time and chain extenders length on surface properties were studied and investigated. Photo-oxidation of PU surface leads to fast increase in surface free energy and its polar component. Simultaneously, the work of water adhesion to polymer increases significantly during UV-irradiation. The higher changes in surface properties, observed by water absorption (%), equilibrium degree of swelling, as well as monitored by ATR-FT-IR and contact angle measurement, were found for the PU samples extended with higher number of methylene unit and irradiation time.     

Recent Advancements in Bulk Metallic Glasses and Their Applications: A Review

Bulk metallic glasses (BMGs), that display extraordinary properties of high strength, corrosion resistance, polymer-like formability, and excellent magnetic properties, are emerging as modern quintessential engineering materials. BMGs have garnered significant research enthusiasm owing to their tremendous technological and scientific standing. In this article, the recent advancements in the field of BMGs and their applications are put in a nutshell. Novel state-of-the-art production routes and nano/microimprinting strategies with salient features capable of circumventing the processing related complexities as well as accelerating modern developments, are briefly summarized. Heterogeneous BMG composite systems that lead to incredible combination of otherwise conflicting properties are highlighted. Biocorrosion studies and recent developments in the field of magnetic BMGs are presented owing to their significance for prospective biomedical and magnetic applications, respectively. In the last section, the current status of BMGs applications in the field of catalysis, biomedical materials, structural materials, functional materials, microelectromechanical systems (MEMS), and micro/macro devices are summed up.     

Analysis of Soil by Magnetic Field Assisted Calibration-Free Laser Induced Breakdown Spectroscopy (CF-LIBS) and Laser Ablation – Time-of-Flight Mass Spectrometry (LA-TOF-MS)

The qualitative and quantitative analysis of soil samples collected from Sialkot, Pakistan (which contains leather industrial plants), has been performed using laser-induced breakdown spectroscopy (LIBS) and laser ablation time of flight mass spectrometry (LA-TOF-MS). The focused beam of a Q-switched Nd: YAG laser (532?nm) was used to ablate the soil samples in air at atmospheric pressure. The optical emission spectra demonstrate the presence of the spectral lines of Si, Fe, Al, Ca, Ti, K, Cr, Mg, Na, Ba, and Li in all of the samples. The emission lines intensities, electron number densities, and excitation temperatures were significantly enhanced in the presence of an external 0.3 T magnetic field applied perpendicular to the plasma plume. A maximum enhancement factor of approximately 8 was observed in the emission intensity. The emergence of several additional lines has also been detected using the magnetic field-assisted LIBS approach. The elemental composition determined using calibration-free laser-induced breakdown spectroscopy (CF-LIBS), with and without magnetic field, reveals that the external magnetic field only adjusts the laser-generated plasma dynamics without affecting the quantitative analysis of the samples. Importantly, the toxic and heavy elements such as chromium and barium were detected and quantified in all of the soil samples by both of these techniques. The variations in the compositional analysis using CF-LIBS with and without the applied magnetic field and LA-TOF-MS were less than 10%.     

SER estimation method for 56 GBaud PAM-4 transmission system

In this Letter, we have proposed a generalized Gaussian probability density function(GGPDF)-based method to estimate the symbol error ratio(SER) for pulse amplitude modulation(PAM-4) in an intensity modulation/direct detection(IM/DD) system. Furthermore, a closed form expression of SERGGDfor PAM-4 has been derived. The performance of the proposed method is evaluated through simulation as well as experimental work.The fitting of probability density functions of the received signal is applied via GGPDF and shape parameters P1 and P2 associated with different PAM-4 levels are determined. The optimum single value of shape parameter P is then calculated to estimate the SER. The mathematical relationship of P with different received optical powers and receiver bandwidths has been determined and verified. The proposed method is a fast and accurate method to estimate SER of a PAM-4 system, which is more reliable and in agreement with the error counting method.     

A novel natural source Vicia faba L. membranes as colourant: development and optimisation of the extraction process using response surface methodology (RSM)

In this research paper, an eco-friendly extraction process of dyes from Vicia faba L. membranes was developed. In this regard, the influence of independent process factors like the weight of material, the extraction time, the temperature and the sodium hydroxide concentration on the natural dye extraction from Vicia faba membranes was investigated. The optimisation of the extraction conditions and the effect evaluation of the different operating parameters were carried out using a Box–Behnken design under response surface methodology. The optimum conditions were found to be 66 °C, 90 min, 5 g and 0.1628 mol·L^?1 for extraction temperature, time, mass of the material and sodium hydroxide concentration, respectively. The efficiency of this extraction process under these optimum conditions was evaluated by measuring the total phenolic content (TPC), the total flavonoid content and the relative colour yield (K/S). In these operating conditions, good fastness ratios were observed for the dyed fabrics.     

Nonequilibrium phase transitions in a simple three-state lattice gas

We investigate the dynamics of a three-state stochastic lattice gas consisting of holes and two oppositely charged species of particles, under the influence of an electric field at zero total charge. Interacting only through an excluded-volume constraint, particles exchange with holes and, on a slower time scale, with each other. Using a combination of Monte Carlo simulations and meanfield equations of motion, we study a set of suitably defined order parameters, their histograms and fluctuations, as well as the current through the system. With increasing particle density and drive, the system first orders into a charge-segregated state, and then disorders again near complete filling. The transition is first order at low densities and turns second order at higher ones. The finite-size and aspect-ratio dependence of characteristic quantities is discussed at the mean-field level.     

Periodic one-dimensional hopping model with one mobile directional impurity

Analytic solution is given in the steady-state limitt for the system of master equations describing a random walk on one-dimensional periodic lattices with arbitrary hopping rates containing one mobile directional impurity (defect bond). Due to the defect, translational invariance is broken, even if all other rates are identical. The structure of master equations leads naturally to the introduction of a new entity, associated with the walker-impurity pair which we call the quasiwalker. The velocities and diffusion constants for both the random walker and impurity are given, being simply related to that of the quasiparticle through physically meaningful equations. Applications in driven diffusive systems are shown, and connections with the Duke-Rubinstein reptation models for gel electrophoresis are discussed.     

Poly(alkyl itaconates) part v copolymers of Selected mono- and di-alkyl esters

Two series of copolymers have been prepared from esters of itaconic acid. Members of type I were synthesised from co-monomers of di-n-alkyl itaconates while type II were composed of a mono-alkyl ester copolymerized with a di-n-alkyl ester. Reactivity ratios were determined for five different copolymers. Both type I and type II copolymers were characterized by differential scanning calorimetry and torsional braid analysis. Several molecular relaxation processes were identified in each series, occurring below the glass transition temperature, Tg. The variation of Tg with type I copolymer composition was examined using Barton's modification of the Gibbs-Di Marzio copolymer equation which gave a satisfactory fit to the data.