Fabrication of multifunctional graphene decorated with bromine and nano-Sb₂O₃ towards high-performance polymer nanocomposites

Despite great advances, it remains highly attractive but challenging to create high-performance polymeric materials combining excellent flame-retardancy and outstanding thermal, mechanical and electrical properties. We herein demonstrate a novel strategy for fabricating a multifunctional nano-additive (Br-Sb2O3@RGO) based on graphene decorated with bromine and nano-Sb2O3. Cone calorimetric tests show that incorporating 10 wt% Br-Sb2O3@RGO into thermoplastic polyurethane (TPU) strikingly prolongs the time to ignition and decreases the peak heat release rate by 72%. Besides, tensile strength and Young's modulus are enhanced by 37% and 820%, respectively. Meanwhile, the electric conductibility is increased by eleven orders of magnitude relative to the TPU matrix. This work provides a promising strategy for addressing the critical bottleneck with the existing flame retardants that only enhance flame retardancy at the expense of mechanical properties of polymeric materials. As-prepared high-performance TPU composites are expected to find many applications, especially in aerospace, tissue engineering, and cables and wires.

Industrial lab-on-a-chip: design, applications and scale-up for drug discovery and delivery

Microfluidics is an emerging and promising interdisciplinary technology which offers powerful platforms for precise production of novel functional materials (e.g., emulsion droplets, microcapsules, and nanoparticles as drug delivery vehicles- and drug molecules) as well as high-throughput analyses (e.g., bioassays, detection, and diagnostics). In particular, multiphase microfluidics is a rapidly growing technology and has beneficial applications in various fields including biomedicals, chemicals, and foods. In this review, we first describe the fundamentals and latest developments in multiphase microfluidics for producing biocompatible materials that are precisely controlled in size, shape, internal morphology and composition. We next describe some microfluidic applications that synthesize drug molecules, handle biological substances and biological units, and imitate biological organs. We also highlight and discuss design, applications and scale up of droplet- and flow-based microfluidic devices used for drug discovery and delivery.

Knitted strain sensor textiles of highly conductive all-polymeric fibers

A scaled-up fiber wet-spinning production of electrically conductive and highly stretchable PU/PEDOT:PSS fibers is demonstrated for the first time. The PU/PEDOT:PSS fibers possess the mechanical properties appropriate for knitting various textile structures. The knitted textiles exhibit strain sensing properties that were dependent upon the number of PU/PEDOT:PSS fibers used in knitting. The knitted textiles show sensitivity (as measured by the gauge factor) that increases with the number of PU/PEDOT:PSS fibers deployed. A highly stable sensor response was observed when four PU/PEDOT:PSS fibers were co-knitted with a commercial Spandex yarn. The knitted textile sensor can distinguish different magnitudes of applied strain with cyclically repeatable sensor responses at applied strains of up to 160%. When used in conjunction with a commercial wireless transmitter, the knitted textile responded well to the magnitude of bending deformations, demonstrating potential for remote strain sensing applications. The feasibility of an all-polymeric knitted textile wearable strain sensor was demonstrated in a knee sleeve prototype with application in personal training and rehabilitation following injury.

Somatostatin modulates G-CSF-induced but not interleukin-3-induced proliferative responses in myeloid 32D cells via activation of somatostatin receptor subtype 2

Somatostatin, originally identified as a peptide involved in neurotransmission, functions as an inhibitor of multiple cellular responses, including hormonal secretion and proliferation. Somatostatin acts through activation of G-protein-coupled receptors of which five subtypes have been identified. We have recently established that human CD34/c-kit expressing hematopoietic progenitors and acute myeloid leukemia (AML) cells exclusively express SSTR2. A major mechanism implicated in the antiproliferative action of somatostatin involves activation of the SH2 domain-containing protein tyrosine phosphatase SHP-1. While 0.1-1 x 10(-9) M of somatostatin, or its synthetic stable analog octreotide, can inhibit G-CSF-induced proliferation of AML cells, little or no effects are seen on GM-CSF- or IL-3-induced responses.
MATERIALS AND METHODS: To study the mechanisms underlying the antiproliferative responses of myeloblasts to somatostatin, clones of the IL-3-dependent murine cell line 32D that stably express SSTR2 and G-CSF receptors were generated. RESULTS: Similar to AML cells, octreotide inhibited G-CSF-induced but not IL-3-induced proliferative responses of 32D[G-CSF-R/SSTR2] cells. Somatostatin induced SHP-1 activity and inhibited G-CSF-induced, but not IL-3-induced, activation of the signal transducer and activator of transcription proteins STAT3 and STAT5.
CONCLUSION: Based on these data and previous results, we propose a model in which recruitment and activation of the tyrosine phosphatase SHP-1 by SSTR2 is involved in the selective negative action of somatostatin on G-CSF-R signaling.

Electrospun nanofibre membranes as wound dressing materials

An effective wound dressing is not only able to protect the wound area from its surroundings to avoid infection and dehydration, but also to speed up the healing process by providing an optimum microenvironment for healing, removing any excess wound exudates, and allowing continuous tissue reconstruction. In this study, two biodegradable polymers, polycaprolactone (PCL) and polyvinyl alcohol (PVA), were used to electrospin nanofibre membranes. The wound dressing performances of these two membranes were compared with the wound dressing performances of protein coated membranes and conventional non-woven cotton wound dressings. In addition, fibre morphology, porous structural property, mechanical properties of the nanofibre membranes, and their drainage capacity and wound skin histology were examined.

Simulation of Mg sheet press cell materials

Major characteristics of Magnesium alloy are low density (= 1.8 g/cm³) and excellent recyclability; therefore Mg is considered as one of low environmental loading materials. The low-density materials, such as Mg, are suitable for the transportation system to reduce the emission of Co2, save energy resource and increase the safety for accidents like corrosions. In the place, cellular materials like aluminum foams are also low-density materials and can be controlled the stress-strain relation. Combination of Mg alloy and cellular materials, that is Mg cell, is one of the most excellent materials for transportation system, because of its ultra low density. safeties, and recycle ability. To make the Mg cellular materials. there are some problems to solve. One is how to make them uniformly to supply them as same perfonnance materials. One is how to make them inexpensively. Most of cellular materials are very expensive because of there are many processes or special fabrication system to make them. To solve these problems. we investigated the press cell materials. The press cell material consists sheets pressed as cell shape and wall. Therefore, it is very easy to make cellular materials and control validation of the performance of each foam materials. In this paper, we simulated compression tests of this new type of Mg alloy cellular materials under dynamic loading to investigate the relation between the compression speed and the compression behavior to show the shock absorbing capability of this new foam material. It is very important to understand their mechanical properties relatcd with cell shapes and wall to be applied widely.

Ion effects in REDOX cycling of conducting polymer based electrochromic materials

Conducting polymer based electrochromic devices were assembled with various ionic liquid (IL) based electrolytes to probe the role of the ion structure on electrochromic performance. When the IL contained the same anion as the dopant ion used in the conducting polymers an enhanced electrochromic performance was observed providing high photopic contrast at low applied potential.

Debond detection in RC structures using piezoelectric materials

This paper presents a technique to detect the delamination between the steel bars and concrete in the reinforced concrete structures. The piezoelectric components are mounted on reinforcing bars that are embedded in RC structures as sensors and actuators to generate and record the signal, which is sensitive to the delamination between the steel bars and concrete. The experimental study is carried out on a concrete slab with different debonds between the rebars and concrete. The test results show that the delamination between the rebars and concrete can be detected with the embedded piezoelectric sensors and actuators.

Microengineering of supramolecular soft materials by design of the crystalline fiber networks

Crystalline spherulitic fiber networks are commonly observed in polymeric and supramolecular functional materials. The elasticity of materials with this type of network is low if interactions between the individual spherulites are weak (mutually exclusive). Improving the elasticity of these materials is necessary because of their important applications in many fields. In this work, the engineering of the microstructures and rheological properties of this type of material is carried out. A small molecule organogel formed by the gelation of N-lauroyl-L-glutamic acid di-n-butylamide (GP-1) in propylene glycol (PG) is used as an example. The elasticity of this material is improved by controlling the thermodynamic driving force, the supersaturation of the gelator, and by using a selected copolymer additive to manipulate the primary nucleation of GP-1. Because of the weak interactions between the GP-1 spherulites, with the same fiber mass, the elasticity of GP-1/PG gel is less than half of those of the other two gels formed by GP-1 and 2-hydroxystearlic acid in solvent benzyl benzoate (BB), which are supported by interconnecting spherulitic fiber networks. This work develops a robust approach to the engineering of supramolecular functional materials especially those with mutually exclusive spherulite fiber networks.

Substrate-induced coagulation (SIC) of nano-disperse carbon black in non-aqueous media : a method of manufacturing highly conductive cathode materials for Li-ion batteries by self-assembly

Substrate-induced coagulation (SIC) is a coating process based on self-assembly for coating different surfaces with fine particulate materials. The particles are dispersed in a suitable solvent and the stability of the dispersion is adjusted by additives. When a surface, pre-treated with a flocculant e.g. a polyelectrolyte, is dipped into the dispersion, it induces coagulation resulting in the deposition of the particles on the surface. A non-aqueous SIC process for carbon coating is presented, which can be performed in polar, aprotic solvents such as N-Methyl-2- pyrrolidinone (NMP). Polyvinylalcohol (PVA) is used to condition the surface of substrates such as mica, copperfoil, silicon-wafers and lithiumcobalt oxide powder, a cathode material used for Li-ion batteries. The subsequent SIC carbon coating produces uniform layers on the substrates and causes the conductivity of lithiumcobalt oxide to increase drastically, while retaining a high percentage of active battery material.

Surface forces and their action in ceramic materials

A descriptive account is given of the surface forces acting between two solids. Different contributions to the force are outlined, with particular attention paid to the underlying mechanisms, and how they are affected by the nature of the medium between the surfaces. This is followed by a discussion of the areas of ceramic science and engineering in which surface forces play a role.

Contact electrification and adhesion between dissimilar materials

Simultaneous measurements of surface force and surface charge demonstrate strong attraction due to the spontaneous transfer of electrical charge from one smooth insulator (mica) to another (silica) as a result of simple, nonsliding contact in dry nitrogen. The measured surface charge densities are 5 to 20 millicoulombs per square meter after contact. The work required to separate the charged surfaces is typically 6 to 9 joules per square meter, comparable to the fracture energies of ionic-covalent materials. Observation of partial gas discharges when the surfaces are approximately 1 micrometer apart gives valuable insight into the charge separation processes underlying static electrical phenomena in general.

Novel carbon materials for thermal energy harvesting

To decrease the consumption of fossil fuels, research has been done on utilizing low grade heat, sourced from industrial waste streams. One promising thermoenergy conversion system is a thermogalvanic cell; it consists of two identical electrodes held at different temperatures that are placed in contact with a redox-based electrolyte [1, 2]. The temperature dependence of the direction of redox reactions allows power to be extracted from the cell [3, 4]. This study aims to increase the power conversion efficiency and reduce the cost of thermogalvanic cells by optimizing the electrolyte and utilizing a carbon based electromaterial, reduced graphene oxide, as electrodes. Thermal conductivity measurements of the K3Fe(CN)6/K4Fe(CN)6 solutions used, indicate that the thermal conductivity decreases from 0.591 to 0.547 W/m K as the concentration is increased from 0.1 to 0.4 M. The lower thermal conductivity allowed a larger temperature gradient to be maintained in the cell. Increasing the electrolyte concentration also resulted in higher power densities, brought about by a decrease in the ohmic overpotential of the cell, which allowed higher values of short circuit current to be generated. The concentration of 0.4 MK3Fe(CN)6/K4Fe(CN)6 is optimal for thermal harvesting applications using R-GO electrodes due to the synergistic effect of the reduction in thermal flux across the cell and the enhancement of power output, on the overall power conversion efficiency. The maximum mass power density obtained using R-GO electrodes was 25.51 W/kg (three orders of magnitude higher than platinum) at a temperature difference of 60 _C and a K3Fe(CN)6/K4Fe(CN)6 concentration of 0.4 M.