Breathable Materials and Hybrid Nanocomposites with Antimicrobial Activity Based on Porous Poly(ε-Caprolactone) Obtained via Environmental Crazing

Structural modification of poly(ε-caprolactone) (PCL) allows the fabrication of new functional materials obtained via the PCL films/fibers stretching in ethanol by the crazing mechanism. Atomic force microscopy, X-ray scattering, and differential scanning calorimetry are employed to study the evolution of PCL structure. It is shown that ethanol plasticizes the polymer being deformed, and the stretching of PCL films/fibers occurs with formation of a fibrillar-porous structure in the interlamellar space. The obtained porous matrices have pore size below 50 nm and bulk porosities of 28% and 48% for fibers and films, respectively. Thermal stabilization of the PCL films’ porous structure made it possible to obtain breathable materials with a vapor permeability of 625–652 g m⁻² per day. The resulting porous PCL fibers and films can be used as matrices for the incorporation of useful additives and preparation of functional nanocomposites (NCs), biodegradable surgical suture, packaging, covering, and textile vapor-permeable materials. Hybrid NCs with antibacterial and fungicidal activities are obtained on the basis of the porous PCL matrices and functional components (5% silver, 1% brilliant green, 28% Betadine, etc.) incorporated into them.     

Multi-walled carbon nanotube-supported Ni@Pd core–shell electrocatalyst for direct formate fuel cells

Journal of Applied Electrochemistry - In the present work, Ni@Pd core–shell nanoparticles are successfully deposited on multi-walled carbon nanotubes as support and investigated their...     

Peculiarities of Electrosynthesis of Polyaniline Coating on Activated Graphite Foil

Protection of Metals and Physical Chemistry of Surfaces - It has been demonstrated that, due to the heterogeneity of the surface of anodized graphite foil (AGF), the adsorption of the aniline...     

A High-Performance Solution-Processed Organic Photodetector for Near-Infrared Sensing

Sensitive detection of near-infrared (NIR) light enables many important applications in both research and industry. Current organic photodetectors suffer from low NIR sensitivity typically due to early absorption cutoff, low responsivity, and/or large dark/noise current under bias. Herein, organic photodetectors based on a novel ultranarrow-bandgap nonfullerene acceptor, CO1-4Cl, are presented, showcasing a remarkable responsivity over 0.5 A W⁻¹ in the NIR spectral region (920–960 nm), which is the highest among organic photodiodes. By effectively delaying the onset of the space charge limited current and suppressing the shunt leakage current, the optimized devices show a large specific detectivity around 10¹² Jones for NIR spectral region up to 1010 nm, close to that of a commercial Si photodiode. The presented photodetectors can also be integrated in photoplethysmography for real-time heart-rate monitoring, suggesting its potential for practical applications.     

Bioactive Polylactide Fibrous Materials Prepared by Crazing Mechanism

Bioactive suture materials made of biodegradable polymers containing biologically active substances are increasingly demanded in contemporary surgical practice. Herein, the functional fibrous materials are produced by structural modification of polylactide (PLA) fibers according to the crazing mechanism in water–ethanol solutions. The threshold of ethanol concentration, at which the breaking elongation of the polymer substantially increases (up to 600–700%), is found to be 30 wt%. The crazing mechanism is employed to fill the porous structure of PLA fibers by different antiseptic substances (brilliant green, iodine, and fuchsin). PLA loaded by 0.8 wt% of brilliant green exhibits antimicrobial activity on Escherichia coli and Candida guilliermondii. The additive is released stepwise for a prolongated time period (2.5 months). The addition of 1–6 wt% iodine dramatically accelerates the polymer degradation in sodium‐phosphate buffer solution at 37 °C. The obtained filled fibers may possess great interest for producing suture materials with prolonged action of functional components and variable degradation times.     

A homogeneity property of discrete‐time systems: Stability and convergence rates

A new definition of homogeneity for discrete‐time systems is introduced. As in the continuous‐time case, the property can be verified algebraically in the transition map of the system, and it implies that a dilation of the initial conditions leads to a scaling of the trajectory. Stability properties and convergence rates of the system's solutions can be established by considering only the homogeneity degree. The existence of homogeneous Lyapunov and Lyapunov‐like functions is proven.     

Compactness of Protein Folds Alters Disulfide-Bond Reducibility by Three Orders of Magnitude: A Comprehensive Kinetic Case Study on the Reduction of Differently Sized Tryptophan Cage Model Proteins

A new approach to monitor disulfide-bond reduction in the vicinity of aromatic cluster(s) has been derived by using the near-UV range (λ=266–293 nm) of electronic circular dichroism (ECD) spectra. By combining the results from NMR and ECD spectroscopy, the 3D fold characteristics and associated reduction rate constants (k) of E19_SS, which is a highly thermostable, disulfide-bond reinforced 39-amino acid long exenatide mimetic, and its N-terminally truncated derivatives have been determined under different experimental conditions. Single disulfide bond reduction of the E19_SS model (with an 18-fold excess of tris(2-carboxyethyl)phosphine, pH 7, 37 °C) takes hours, which is 20–30 times longer than that expected, and thus, would not reach completion by applying commonly used reduction protocols. It is found that structural, steric, and electrostatic factors influence the reduction rate, resulting in orders of magnitude differences in reduction half-lives (900>t_1/2>1 min) even for structurally similar, well-folded derivatives of a small model protein.     

Thermoelectric properties of W1−xNbxSe2−ySy polycrystalline compounds

We investigate the thermoelectric properties of bulk polycrystalline samples of WSe₂-based compounds with partial substitutions in the cationic (W) and the anionic (Se) sublattices in the temperature range from 4.2 to 650 K. The substitution of W for Nb leads to a significant increase in the charge carrier concentration, however, deteriorates the charge carrier mobility. In contrast, the substitution of selenium for sulfur increases the charge carrier mobility, the thermal conductivity, and the Seebeck coefficient but conductivity changes non-monotonical. We show that the addition of sulfur in anionic sublattice affects the grain sizes in the polycrystalline material. Using substitutions in the anionic and cationic sublattices, we find the optimal ratio of the elements for better thermoelectric efficiency. The W_0.98Nb_0.02Se_1.7S_0.3 sample showed the best value of the figure of merit ZT = 0.26 (T = 650 K).     

The Effect of Carbon Substrate Morphology on the Electrochemical Performance of Electroactive Composite Coatings Based on Poly(3,6-di(3-aminophenylene)amino-2,5-dichloro-1,4-benzoquinone)

Protection of Metals and Physical Chemistry of Surfaces - Electroactive composite coatings (CCs) are prepared on the basis of 3,6-di(3-aminophenylene)amino-2,5-dichloro-1,4-benzoquinone (DAPADCB)...     

Properties of a single SnO2:Zn2SnO4 – Functionalized nanowire based nanosensor

Tin oxide nanowires (SnO₂ NWs) exhibit large potential for applications in sensor and detector technology. Using a flame transport synthesis method, high-quality single crystalline SnO₂ nanowires (NWs) with Zn₂SnO₄ dots functionalized surface were synthesized on a large scale. The individual SnO₂:Zn₂SnO₄ nanowire based ultraviolet photodetector and ethanol vapors nanosensors were fabricated by contacting an individual nanowire to pre-patterned Au electrodes via a FIB/SEM system. The photodetector structure exhibited excellent photoconductive performance in terms of high response to the 375 nm ultraviolet light irradiation, ultra-fast response and recovery time at different temperatures (25–300 K). It also showed a long term stability and reliability. The n-type semiconducting behavior of the SnO₂:Zn₂SnO₄, forms an excellent material for fabricating highly sensitive and rapid responding sensors, which will enable the development of high-performance multi-functional devices.