Pseudo-Elasticity and Variable Electro-Conductivity Mediated by Size-Dependent Deformation Twinning in Molybdenum Nanocrystals.

Deformation twinning merits attention because of its intrinsic importance as a mode of energy dissipation in solids. Herein, through the atomistic electron microscopy observations, the size-dependent twinning mechanisms in refractory body-centered cubic molybdenum nanocrystals (NCs) under tensile loading are shown. Two distinct twinning mechanisms involving the nucleation of coherent and inclined twin boundaries (TBs) are uncovered in NCs with smaller (diameter < ≈5 nm) and larger (diameter > ≈5 nm) diameters, respectively. Interestingly, the ultrahigh pseudo-elastic strain of ≈41% in sub-5 nm-sized crystals is achieved through the reversible twinning mechanism. A typical TB cross-transition mechanism is found to accommodate the NC re-orientation during the pseudo-elastic deformation. More importantly, the effects of different types of TBs on the electrical conductivity based on the repeatable experimental measurements and first-principles calculations are quantified. These size-dependent mechanical and electrical properties may prove essential in advancing the design of next-generation flexible nanoelectronics.

Field Modeling of the Influence of Defects Caused by Bending of Conductive Textronic Layers on Their Electrical Conductivity.

One of the critical parameters of thin-film electrically conductive structures in wearable electronics systems is their conductivity. In the process of using such structures, especially during bending, defects and microcracks appear that affect their electrical parameters. Understanding these phenomena in the case of thin layers made on flexible substrates, including textile ones, which are incorporated in sensors that monitor vital functions, is a key aspect when applying such solutions. Cracks and defects in such structures appearing during their use may be critical for the correct operation of such systems. In this study, the influence of defects resulting from the repeated bending of the conductive layer on its conductivity is analyzed. The anisotropic and partly stochastic characteristics of the defects are also taken into account. The defects are modeled in the form of broken lines, whose segments are generated in successive iterative steps, thus simulating the gradual wear of the layer material. The lengths and inclinations of these sections are determined randomly, which makes it possible to consider the irregularity of real defects of this type. It was found that near the percolation threshold, defects with a more irregular shape have a dominant effect on the reduction of conductivity due to the greater probability of their connection. The simulation results were compared with the experimental data. It was found that the dependence of the conductivity of the conductive layer on the number of bends is logarithmic. This allowed for the derivation of a formula linking the iteration number of the simulation procedure with the number of bends. Improving the strength of such layers is a technological challenge for researchers.

Full-Chain FeCl3 Catalyzation Is Sufficient to Boost Cellulase Secretion and Cellulosic Ethanol along with Valorized Supercapacitor and Biosorbent Using Desirable Corn Stalk.

Cellulosic ethanol is regarded as a perfect additive for petrol fuels for global carbon neutralization. As bioethanol conversion requires strong biomass pretreatment and overpriced enzymatic hydrolysis, it is increasingly considered in the exploration of biomass processes with fewer chemicals for cost-effective biofuels and value-added bioproducts. In this study, we performed optimal liquid-hot-water pretreatment (190 °C for 10 min) co-supplied with 4% FeCl3 to achieve the near-complete biomass enzymatic saccharification of desirable corn stalk for high bioethanol production, and all the enzyme-undigestible lignocellulose residues were then examined as active biosorbents for high Cd adsorption. Furthermore, by incubating Trichoderma reesei with the desired corn stalk co-supplied with 0.05% FeCl3 for the secretion of lignocellulose-degradation enzymes in vivo, we examined five secreted enzyme activities elevated by 1.3-3.0-fold in vitro, compared to the control without FeCl3 supplementation. After further supplying 1:2 (w/w) FeCl3 into the T. reesei-undigested lignocellulose residue for the thermal-carbonization process, we generated highly porous carbon with specific electroconductivity raised by 3-12-fold for the supercapacitor. Therefore, this work demonstrates that FeCl3 can act as a universal catalyst for the full-chain enhancement of biological, biochemical, and chemical conversions of lignocellulose substrates, providing a green-like strategy for low-cost biofuels and high-value bioproducts.

Electrospun electroconductive constructs of aligned fibers for cardiac tissue engineering.

Myocardial infarction remains the leading cause of death in the western world. Since the heart has limited regenerative capabilities, several cardiac tissue engineering (CTE) strategies have been proposed to repair the damaged myocardium. A novel electrospun construct with aligned and electroconductive fibers combining gelatin, poly(lactic-co-glycolic) acid and polypyrrole that may serve as a cardiac patch is presented. Constructs were characterized for fiber alignment, surface wettability, shrinkage and swelling behavior, porosity, degradation rate, mechanical properties, and electrical properties. Cell-biomaterial interactions were studied using three different types of cells, Neonatal Rat Ventricular Myocytes (NRVM), human lung fibroblasts (MRC-5) and induced pluripotent stem cells (iPSCs). All cell types showed good viability and unique organization on construct surfaces depending on their phenotype. Finally, we assessed the maturation status of NRVMs after 14 days by confocal images and qRT-PCR. Overall evidence supports a proof-of-concept that this novel biomaterial construct could be a good candidate patch for CTE applications.

Fluorometric and electrochemical dual-mode nanoprobe for tetracycline by using a nanocomposite prepared from carbon nitride quantum dots and silver nanoparticles.

A fluorometric and electrochemical dual-mode method is described for sensitive and specific detection of tetracycline (Tc). A novel nanoprobe was designed that is making use of a Tc-specific aptamer (apta), carbon nitride quantum dots (CNQDs) and silver nanoparticles (AgNPs). The aptamer was linked to the CNQDs which then were used as templates to synthesize the apta-CNQD@AgNP nanocomposites. The blue fluorescence of the nanocomposites (with excitation/emission maxima at 365/440 nm) is quenched. The addition of Tc leads to fluorescence recovery and a decrease in the electroconductivity of a gold electrode modified with apta-CNQD@AgNPs. The fluorometric method has a linear response in the 0.1 µM - 10 mM Tc concentration range and a 15 nM detection limit. The amperometric method (best performed at a working voltage of 0.21 V vs. Ag/AgCl) has a linear response in the 1 nM to 0.1 mM Tc concentration range and a 0.26 nM detection limit. Recoveries of Tc from spiked milk samples were comparable to data obtained by HPLC. Graphical abstractA fluorometric and electrochemical dual-mode nanoprobe (apta-CNQD@AgNPs) was prepared from aptamer (apta), carbon nitride quantum dots (CNQDs) and silver nanoparticles (AgNPs). The nanoprobe can be used for determination of tetracycline (Tc) based on fluorescence recovery of apta-CNQD@AgNPs and a decrease in the electroconductivity of a gold electrode modified with apta-CNQD@AgNPs.

Soil salinity and moisture content under non-native Tamarix species.

This study investigated, soil salinity and moisture content under the exotic Tamarix in the Olifants River, South Africa, where they predominantly occur. Soil electro-conductivity (EC) was mapped using the electromagnetic induction (EMI) device (EM38 sensor), in three transects laid along the river from as close to the water source outward towards the bank of the River at 50 m apart. This was supported by three soil EC and moisture measurements from each of the three transects at a soil depth of 0-100 cm at intervals of 10 cm using soil EC meter and Amplitude Domain Reflectometry (ADR) sensor, respectively. The highest salt concertation (3,000 mS/m or 19,500 ppm) was found at a depth of 30-40 cm under the dense Tamarix species. The highest soil moisture (20-40%) was also found at the same depth under the Tamarix, suggesting a hydraulic lift of water to the top 30-40 cm, where the Tamarix fine roots for water absorption occur. It also confirms that the distance from water point and Tamarix plant density affect salt leaching depth and amount of litter decomposition, respectively, which is the main source of salt deposition in soil.

Highly conductive, stretchable, and biocompatible graphene oxide biocomposite hydrogel for advanced tissue engineering.

The importance of hydrogels in tissue engineering cannot be overemphasized due to their resemblance to the native extracellular matrix. However, natural hydrogels with satisfactory biocompatibility exhibit poor mechanical behavior, which hampers their application in stress-bearing soft tissue engineering. Here, we describe the fabrication of a double methacrylated gelatin bioink covalently linked to graphene oxide (GO) via a zero-length crosslinker, digitally light-processed (DLP) printable into 3D complex structures with high fidelity. The resultant natural hydrogel (GelGOMA) exhibits a conductivity of 15.0 S m-1as a result of the delocalization of theπ-orbital from the covalently linked GO. Furthermore, the hydrogel shows a compressive strength of 1.6 MPa, and a 2.0 mm thick GelGOMA can withstand a 1.0 kg ms-1momentum. The printability and mechanical strengths of GelGOMAs were demonstrated by printing a fish heart with a functional fluid pumping mechanism and tricuspid valves. Its biocompatibility, electroconductivity, and physiological relevance enhanced the proliferation and differentiation of myoblasts and neuroblasts and the contraction of human-induced pluripotent stem cell-derived cardiomyocytes. GelGOMA demonstrates the potential for the tissue engineering of functional hearts and wearable electronic devices.

Structure of native oligomeric Sprouty2 by electron microscopy and its property of electroconductivity.

Receptor tyrosine kinases (RTKs) regulate many cellular processes, and Sprouty2 (Spry2) is known as an important regulator of RTK signaling pathways. Therefore, it is worth investigating the properties of Spry2 in more detail. In this study, we found that Spry2 is able to self-assemble into oligomers with a high-affinity KD value of approximately 16nM, as determined through BIAcore surface plasmon resonance analysis. The three-dimensional (3D) structure of Spry2 was resolved using an electron microscopy (EM) single-particle reconstruction approach, which revealed that Spry2 is donut-shaped with two lip-cover domains. Furthermore, the method of energy dispersive spectrum obtained through EM was analyzed to determine the elements carried by Spry2, and the results demonstrated that Spry2 is a silicon- and iron-containing protein. The silicon may contribute to the electroconductivity of Spry2, and this property exhibits a concentration-dependent feature. This study provides the first report of a silicon- and iron-containing protein, and its 3D structure may allow us (1) to study the potential mechanism through the signal transduction is controlled by switching the electronic transfer on or off and (2) to develop a new type of conductor or even semiconductor using biological or half-biological hybrid materials in the future.

Electroconductivity, a regenerative engineering approach to reverse rotator cuff muscle degeneration.

Muscle degeneration is one the main factors that lead to the high rate of retear after a successful repair of rotator cuff (RC) tears. The current surgical practices have failed to treat patients with chronic massive rotator cuff tears (RCTs). Therefore, regenerative engineering approaches are being studied to address the challenges. Recent studies showed the promising outcomes of electroactive materials (EAMs) on the regeneration of electrically excitable tissues such as skeletal muscle. Here, we review the most important biological mechanism of RC muscle degeneration. Further, the review covers the recent studies on EAMs for muscle regeneration including RC muscle. Finally, we will discuss the future direction toward the application of EAMs for the augmentation of RCTs.

Development of La1.7Ca0.3Ni1-yCuyO4+δ Materials for Oxygen Permeation Membranes and Cathodes for Intermediate-Temperature Solid Oxide Fuel Cells.

The La1.7Ca0.3Ni1-yCuyO4+δ (y = 0.0-0.4) nickelates, synthesized via a solid-state reaction method, are investigated as prospective materials for oxygen permeation membranes and IT-SOFC cathodes. The obtained oxides are single-phase and possess a tetragonal structure (I4/mmm sp. gr.). The unit cell parameter c and the cell volume increase with Cu-substitution. The interstitial oxygen content and total conductivity decrease with Cu-substitution. The low concentration of mobile interstitial oxygen ions results in a limited oxygen permeability of Cu-substituted La1.7Ca0.3NiO4+δ ceramic membranes. However, increasing the Cu content over y = 0.2 induces two beneficial effects: enhancement of the electrochemical activity of the La1.7Ca0.3Ni1-yCuyO4+δ (y = 0.0; 0.2; 0.4) electrodes and decreasing the sintering temperature from 1200 °C to 900 °C. Enhanced electrode activity is due to better sintering properties of the developed materials ensuring excellent adhesion and facilitating the charge transfer at the electrode/electrolyte interface and, probably, faster oxygen exchange in Cu-rich materials. The polarization resistance of the La1.7Ca0.3Ni1.6Cu0.4O4+δ electrode on the Ce0.8Sm0.2O1.9 electrolyte is as low as 0.15 Ω cm2 and 1.95 Ω cm2 at 850 °C and 700 °C in air, respectively. The results of the present work demonstrate that the developed La1.7Ca0.3Ni0.6Cu0.4O4+δ-based electrode can be considered as a potential cathode for intermediate-temperature solid oxide fuel cells.

An electro-conductive hybrid scaffold as an artificial Bruch's membrane.

Many research groups have investigated the various kinds of scaffolds to mimic the natural Bruch's membrane (BM) and support the retinal pigmented epithelial cells to form an organized cellular monolayer. While using prosthetic BM is identified as a promising treatment of age-related macular degeneration (AMD), a degenerative and progressive retinal disease, the effects of different signals such as electrical and morphological cues on the retinal pigmented epithelial (RPE) cells are still unknown. In this study, a laminated and conductive hydrogel/fiber composite scaffold by adding conductive polyaniline (PANi) to the scaffold's nanofibrous phase was prepared. This hybrid scaffold offers the closest morphology to the native structure of the human Bruch's membrane by imitating the inner and outer collagenous layer and induces the electrical signal to the scaffold to assess the electrical cue on behaviors of polarized retinal pigmented epithelial cells in the retina. The electrospun nanofibrous phase consisted of gelatin-Polyaniline in different ratios incorporated into the hydrogel precursor, a blend of gelatin and 4-armed PEG. We used a novel dual crosslinking process by incorporating the exposure of gamma irradiation and glutaraldehyde vapor treatment to construct the scaffold's hydrogel phase. The results showed the best composition was the sample which included the 40/60, Polyaniline/gelatin nanofiber sheets ratio because this scaffold revealed a 2.66 ± 0.33 MPa, Young's modulus and 1.84 ± 0.21 S/cm, electrochemical conductivity, which are close to the main features of native Bruch's membrane. In addition, this scaffold showed good biocompatibility by reaching 83.47% cell viability.

Synergistic Effect of Screen-Printed Single-Walled Carbon Nanotubes and Phosphorylated Cellulose Nanofibrils on Thermophysiological Comfort, Thermal/UV Resistance, Mechanical and Electroconductive Properties of Flame-Retardant Fabric.

Single-walled carbon nanotubes (SWCNTs) and phosphorylated nanocellulose fibrils (PCNFs) were used as functional screen-print coatings on flame-retardant (FR) fabric, to improve its thermal resistance and thermophysiological comfort (wetting, water vapour and heat transmission) properties, while inducing it with electrical conductivity and UV protection. The effect of PCNF printing, followed by applying a hydrophobic polyacrylate (AP), on the same (back/B, turned outwards) or other (front/F, turned towards skin) side of the fabric, with and without the addition of 0.1-0.4 wt% SWCNTs, was studied by determining the amount of applied coating and its distribution (microscopic imaging), and measuring the fabric's colour, air permeability, thickness, mechanical, flame and abrasion resistance properties. Due to the synergistic effect of PCNF and SWCNTs, both-sided printed fabric (front-side printed with PCNF and back-side with SWCNTs within AP) resulted in an increased heat transfer (25%) and an improved thermal resistance (shift of degradation temperature by up to 18 °C towards a higher value) and UV protection (UPF of 109) without changing the colour of the fabric. Such treatment also affected the moisture management properties with an increased water-vapour transfer (17%), reduced water uptake (39%) and asymmetric wettability due to the hydrophilic front (Contact Angle 46°) and hydrophobic back (129°) side. The increased tensile (16%) and tear (39%) strengths were also assessed in the warp direction, without worsening the abrasion resistance of the front-side. A pressure-sensing electrical conductivity (up to 4.9∙10-4 S/cm with an increase to 12.0∙10-4 S/cm at 2 bars) of the SWCNT-printed side ranks the fabric among the antistatic, electrostatic discharge (ESD) or electromagnetic interference (EMI) shielding protectives.

Photo-Electro Active Nanocomposite Silk Hydrogel for Spatiotemporal Controlled Release of Chemotherapeutics: An In Vivo Approach toward Suppressing Solid Tumor Growth.

Conventional systemic chemotherapeutic regimens suffer from challenges such as nonspecificity, shorter half-life, clearance of drugs, and dose-limiting toxicity. Localized delivery of chemotherapeutic drugs through noninvasive spatiotemporally controllable stimuli-responsive drug delivery systems could overcome these drawbacks while utilizing drugs approved for cancer treatment. In this regard, we developed photoelectro active nanocomposite silk-based drug delivery systems (DDS) exhibiting on-demand drug release in vivo. A functionally modified single-walled carbon nanotube loaded with doxorubicin (DOX) was embedded within a cross-linker free silk hydrogel. The resultant nanocomposite silk hydrogel showed electrical field responsiveness and near-infrared (NIR) laser-induced hyperthermal effect. The remote application of these stimuli in tandem or independent manner led to the increased thermal and electrical conductivity of nanocomposite hydrogel, which effectively triggered the intermittent on-demand drug release. In a proof-of-concept in vivo tumor regression study, the nanocomposite hydrogel was administered in a minimally invasive way at the periphery of the tumor by covering most of it. During the 21-day study, drastic tumor regression was recorded upon regular stimulation of nanocomposite hydrogel with simultaneous or individual external application of an electric field and NIR laser. Tumor cell death marker expression analysis uncovered the induction of apoptosis in tumor cells leading to its shrinkage. Heart ultrasound and histology revealed no cardiotoxicity associated with localized DOX treatment. To our knowledge, this is also the first report to show the simultaneous application of electric field and NIR laser in vivo for localized tumor therapy, and our results suggested that such strategy might have high clinical translational potential.

Structure and sensor properties of thin ordered solid films.

Miniaturized gas sensors and biosensors based on nanostructured sensing elements have attracted considerable interest because these nanostructured materials can be used to significantly improve sensor sensitivity and the response time. We report here on a generic, reversible sensing platform based on hybrid nanofilms. Thin ordered Langmuir-Blodgett (LB) films built of fluorene derivatives were used as effective gas sensors for both oxidative and reductive analytes. A novel immobilization method based on thin LB films as a matrix has been developed for construction of sensing protein layers. Biomolecules can often be incorporated into and immobilized on Langmuir-Blodgett films using adsorption methods or by covalent immobilization of proteins. The sensor sensitisation was achieved by an amphiphilic N-alkyl-bis(thiophene)arylenes admixed into the film. The interlaced derivative was expected to facilitate the electron transfer, thereby enhancing the sensor sensitivity. The results suggest that this may be very promising approach for exploring the interactions between proteins and high throughput detection of phenol derivatives in wastewater.

Integration of Polypyrrole Electrode into Piezoelectric PVDF Energy Harvester with Improved Adhesion and Over-Oxidation Resistance.

Smart textiles for wearable devices require flexibility and a lightweight, so in this study, a soft polypyrrole (PPy) electrode system was integrated into a piezoelectric polyvinylidenefluoride (PVDF) energy harvester. The PVDF energy harvester integrated with a PPy electrode had the piezoelectric output voltage of 4.24-4.56 V, while the PVDF energy harvester with an additional aluminum-foil electrode exhibited 2.57 V. Alkaline treatment and chemical vapor deposition with n-dodecyltrimethoxysilane (DTMS) were employed to improve the adhesion between the PVDF and PPy and the resistance to over-oxidation in aqueous solutions. The PVDF film modified by an alkaline treatment could have the improved adhesion via the introduction of polar functional groups to its surface, which was confirmed by the ultrasonication. The surface hydrophobicity of the PPy electrode was enhanced by the DTMS coating, resulting in the improvement of the resistance to over-oxidation with a water contact angle of 111°. Even with the hydrophobic coating, the electrodes remained electroconductive and continued to transfer an electric charge, maintaining the piezoelectricity of the PVDF film. The developed electrode-integrated energy harvester is expected to be applied to smart textiles because it offers the advantages of efficient piezoelectric generation, flexibility, and durability.

Conductive Silk-Polypyrrole Composite Scaffolds with Bioinspired Nanotopographic Cues for Cardiac Tissue Engineering.

We report on the development of bioinspired cardiac scaffolds made from electroconductive acid-modified silk fibroin-poly(pyrrole) (AMSF+PPy) substrates patterned with nanoscale ridges and grooves reminiscent of native myocardial extracellular matrix (ECM) topography to enhance the structural and functional properties of cultured human pluripotent stem cells (hPSC)-derived cardiomyocytes. Nanopattern fidelity was maintained throughout the fabrication and functionalization processes, and no loss in conductive behavior occurred due to the presence of the nanotopographical features. AMSF+PPy substrates were biocompatible and stable, maintaining high cell viability over a 21-day culture period while displaying no signs of PPy delamination. The presence of anisotropic topographical cues led to increased cellular organization and sarcomere development, and electroconductive cues promoted a significant improvement in the expression and polarization of connexin 43 (Cx43), a critical regulator of cell-cell electrical coupling. The combination of biomimetic topography and electroconductivity also increased the expression of genes that encode key proteins involved in regulating the contractile and electrophysiological function of mature human cardiac tissue.

Efficacy and Safety of an Anti-aging Technology for the Treatment of Facial Wrinkles and Skin Moisturization.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of five topical test products intended to reduce the appearance of lines and wrinkles, increase skin moisturization, and reduce transepidermal water loss. DESIGN: Two studies-a controlled clinical trial for each individual test product and an experience trial involving more than 200 patients using a strategic combination of products-were done. Test products included a day facial cream, a night facial cream, an eye cream, a day lip cream, and a night lip cream. SETTING: The setting for the first study was AMA Laboratories (New York, New York)and 19 physician practices for the second. PARTICIPANTS: For the first study, participants were recruited via advertisements, phone solicitation, or electronic media. Patients of the second study (N=222) were from 19 physician practices. MEASUREMENTS: For the first study, efficacies of the facial and eye creams were determined by measuring the surface evaluation of living skin, transepidermal water loss, and electroconductivity. Efficacy of the lip creams was evaluated by measuring surface evaluation of living skin and electroconductivity. These evaluation parameters were measured at the test sites prior to initial application of test product,15 minutes after the initial application, and at seven, 14, 28, and 56 days of test product use. For the second study, each subject completed an assessment of the topical product(s) effects after four weeks of use. RESULTS: With each of the five topical test products, an improvement in surface evaluation of living skin became apparent within 15 minutes of initial application of test products and continued for at least 56 days of regular use. Electroconductivity data showed that each product dramatically increased the moisture content in the skin almost immediately after application and for at least 56 days. Improvement in transepidermal water loss was nearly immediate and continued over time with the day and night facial creams and eye cream. For the experience trial, a significant majority of subjects achieved one or more endpoints within 30 days or less. CONCLUSION: The facial, eye, and lip creams are effective anti-aging products that reduce the appearance of both fine and coarse lines and wrinkles, dramatically increase the moisturization of the skin, and, in the case of the face and eye products, reduces transepidermal water loss. These changes last for at least 56 days without significant adverse effects.