Preparation and Characterization of Highly Aligned Carbon Nanotubes/Polyacrylonitrile Composite Nanofibers

Programming gel automata shapes using DNA instructions

The ability to transform matter between numerous physical states or shapes without wires or external devices is a major challenge for robotics and materials design. Organisms can transform their shapes using biomolecules carrying specific information and localize at sites where transitions occur. Here, we introduce gel automata, which likewise can transform between a large number of prescribed shapes in response to a combinatorial library of biomolecular instructions. Gel automata are centimeter-scale materials consisting of multiple micro-segments. A library of DNA activator sequences can each reversibly grow or shrink different micro-segments by polymerizing or depolymerizing within them. We develop DNA activator designs that maximize the extent of growth and shrinking, and a photolithography process for precisely fabricating gel automata with elaborate segmentation patterns. Guided by simulations of shape change and neural networks that evaluate gel automata designs, we create gel automata that reversibly transform between multiple, wholly distinct shapes: four different letters and every even or every odd numeral. The sequential and repeated metamorphosis of gel automata demonstrates how soft materials and robots can be digitally programmed and reprogrammed with information-bearing chemical signals.

Structural Elucidation of a Metagenomic Urethanase and Its Engineering Towards Enhanced Hydrolysis Profiles

While plastics like polyethylene terephthalate can already be degraded efficiently by the activity of hydrolases, other synthetic polymers like polyurethanes (PUs) and polyamides (PAs) largely resist biodegradation. In this study, we solved the first crystal structure of the metagenomic urethanase UMG-SP-1, identified highly flexible loop regions to comprise active site residues, and targeted a total of 20 potential hot spots by site-saturation mutagenesis. Engineering campaigns yielded variants with single mutations, exhibiting almost 3- and 8-fold improved activity against highly stable N-aryl urethane and amide bonds, respectively. Furthermore, we demonstrated the release of the corresponding monomers from a thermoplastic polyester-PU and a PA (nylon 6) by the activity of a single, metagenome-derived urethanase after short incubation times. Thereby, we expanded the hydrolysis profile of UMG-SP-1 beyond the reported low-molecular weight carbamates. Together, these findings promise advanced strategies for the bio-based degradation and recycling of plastic materials and waste, aiding efforts to establish a circular economy for synthetic polymers.

Scaffold-Based Poly(Vinylidene Fluoride) and Its Copolymers: Materials, Fabrication Methods, Applications, and Perspectives

Tissue engineering involves implanting grafts into damaged tissue sites to guide and stimulate the formation of new tissue, which is an important strategy in the field of tissue defect treatment. Scaffolds prepared in vitro meet this requirement and are able to provide a biochemical microenvironment for cell growth, adhesion, and tissue formation. Scaffolds made of piezoelectric materials can apply electrical stimulation to the tissue without an external power source, speeding up the tissue repair process. Among piezoelectric polymers, poly(vinylidene fluoride) (PVDF) and its copolymers have the largest piezoelectric coefficients and are widely used in biomedical fields, including implanted sensors, drug delivery, and tissue repair. This paper provides a comprehensive overview of PVDF and its copolymers and fillers for manufacturing scaffolds as well as the roles in improving piezoelectric output, bioactivity, and mechanical properties. Then, common fabrication methods are outlined such as 3D printing, electrospinning, solvent casting, and phase separation. In addition, the applications and mechanisms of scaffold-based PVDF in tissue engineering are introduced, such as bone, nerve, muscle, skin, and blood vessel. Finally, challenges, perspectives, and strategies of scaffold-based PVDF and its copolymers in the future are discussed.

Pioneering the preparation of porous PIM-1 membranes for enhanced water vapor flow

In this study, porous polymers of intrinsic microporosity (PIM-1) membranes were prepared by non-solvent induced phase inversion (NIPS) and investigated for water vapor transport in view of their application in membrane distillation (MD). Due to the lack of high boiling point solvents for PIM-1 that are also water miscible, the mixture of tetrahydrofuran (THF) and N-methyl-2-pyrrolidone (NMP) was found to be optimal for the formation of a membrane with a developed porous system both on the membrane surface and in the bulk. PIM-1 was synthesized by using low and high temperature methods to observe how molecular weight effects the membrane structure. Low molecular weight PIM-1 was produced at low temperatures, while high molecular weight PIM-1 was obtained at high temperatures. Several membranes were prepared, including PM-6, PM-9, and PM-11 from low molecular weight PIM-1, and PM-13 from high molecular weight PIM-1. Scanning electron microscopy (SEM) was used to image the surface and cross-section of different porous PIM-1 membranes. Among all the PIM-1 membranes (PM) obtained, PM-6, PM-9, PM-11 and PM-13 showed the most developed porous structure, while PM-13 showed large voids in the bulk of the membrane. Contact angle measurements showed that all PIM-1 porous membranes are highly hydrophobic. Liquid water flux measurements showed that PM-6, PM-9 and PM-11 showed minimal water fluxes due to small surface pore size, while PM-13 showed a high water flux due to a large surface pore size. Water vapor transport measurements showed high permeance values for all membranes, demonstrating the applicability of the developed membranes for MD. In addition, a thin film composite (TFC) membrane with PIM-1 selective layer was prepared and investigated for water vapor transport to compare with porous PIM-1 membranes. The TFC membrane showed an approximately 4-fold lower vapor permeance than porous membranes. Based on these results, we postulated that the use of porous PIM-1 membranes could be promising for MD due to their hydrophobic nature and the fact that the porous membranes allow vapor permeability through the membrane but not liquid water. The TFC membrane can be used in cases where the transfer of water-soluble contaminants must be absolutely avoided.

Quality-by-Design Based Development of Doxycycline Hyclate-Loaded Polymeric Microspheres for Prolonged Drug Release

This study explores a novel approach to address the challenges of delivering highly water-soluble drug molecules by employing hydrophobic ion-pairing (HIP) complexes within poly (lactic-co-glycolic acid) (PLGA) microspheres. The HIP complex, formed between doxycycline hyclate (DH) and docusate sodium (DS), renders the drug hydrophobic. The development of the microspheres was done using the QbD approach, namely, Box-Behnken Design (BBD). A comprehensive characterization of the HIP complex confirmed the successful conversion of DH. DH and the HIP complex were effectively loaded into PLGA microspheres using the oil-in-water (O/W) emulsion solvent evaporation method. Results demonstrated significant improvements in percentage entrapment efficiency (% EE) and drug loading (% DL) for DH within the HIP complex-loaded PLGA microspheres compared to DH-loaded microspheres alone. Additionally, the initial burst release of DH reduced to 3% within the initial 15 min, followed by sustained drug release over 8 days. The modified HIP complex strategy offers a promising platform for improving the delivery of highly water-soluble small molecules. It provides high % EE, % DL, minimal initial burst release, and sustained release, thus having the potential to enhance patient compliance and drug delivery efficiency.

Wound healing strategies based on nanoparticles incorporated in hydrogel wound patches

The intricate, tightly controlled mechanism of wound healing that is a vital physiological mechanism is essential to maintaining the skin's natural barrier function. Numerous studies have focused on wound healing as it is a massive burden on the healthcare system. Wound repair is a complicated process with various cell types and microenvironment conditions. In wound healing studies, novel therapeutic approaches have been proposed to deliver an effective treatment. Nanoparticle-based materials are preferred due to their antibacterial activity, biocompatibility, and increased mechanical strength in wound healing. They can be divided into six main groups: metal NPs, ceramic NPs, polymer NPs, self-assembled NPs, composite NPs, and nanoparticle-loaded hydrogels. Each group shows several advantages and disadvantages, and which material will be used depends on the type, depth, and area of the wound. Better wound care/healing techniques are now possible, thanks to the development of wound healing strategies based on these materials, which mimic the extracellular matrix (ECM) microenvironment of the wound. Bearing this in mind, here we reviewed current studies on which NPs have been used in wound healing and how this strategy has become a key biotechnological procedure to treat skin infections and wounds.

Fabrication, Microstructures and Sensor Applications of Highly Ordered Electrospun Nanofibers: A Review

The review summarizes the fabrication, microstructures, and sensor applications of highly ordered electrospun nanofibers. In the traditional electrospinning process, electrospun nanofibers usually have disordered or random microstructures due to the chaotic oscillation of the electrospinning jet. Different electrospinning methods can be formed by introducing external forces, such as magnetic, electric, or mechanical forces, and ordered nanofibers can be collected. The microstructures of highly ordered nanofibers can be divided into three categories: uniaxially ordered nanofibers, biaxially ordered nanofibers and ordered scaffolds. The three microstructures are each characterized by being ordered in different dimensions. The regulation and control of the ordered microstructures can promote electrospun nanofibers' mechanical and dielectric strength, surface area and chemical properties. Highly ordered electrospun nanofibers have more comprehensive applications than disordered nanofibers do in effect transistors, gas sensors, reinforced composite materials and tissue engineering. This review also intensively summarizes the applications of highly ordered nanofibers in the sensor field, such as pressure sensors, humidity sensors, strain sensors, gas sensors, and biosensors.

Terahertz antireflection coatings employing off-the-shelf adhesive tapes

We demonstrate the feasibility of making antireflection coatings (ARCs) for terahertz (THz) light using multilayered polymer films from commercial adhesive tapes. Efficient and low-cost ARCs in the THz range are not conveniently available. Our economical approach can mitigate many of the experimental challenges posed by Fresnel reflection. Harnessing a time-domain THz spectrometer, we demonstrate the performance of several types of multilayer coatings on a variety of substrates. By varying layer stacking and thicknesses, spectral performance can be tuned and optimized for specific applications. Good agreement is found between experimental measurement and analytic calculations evaluating the performance of these multilayer tape ARCs.

Effect of Ni-Coated Carbon Nanotubes Additions on the Eutectic Sn-0.7Cu Lead-Free Composite Solder

Sn-0.7Cu-based (all in wt.% unless specified otherwise) composite solders functionalized with Ni-coated carbon nanotubes (CNTs) with various weight proportions ranging from 0.01 to 0.2 wt.% were successfully produced. The Ni-coated CNTs were synthesized with discontinuous nickel coating by an improved electroless nickel plating technique. The microstructural, melting and wetting properties of Sn-0.7Cu-based composite solders were evaluated as a function of different amounts of Ni-coated CNTs addition. Compared to Sn-0.7Cu, it was observed that the microstructure of the composite solder added to the Ni-coated CNTs was still composed of the intermetallic compound Cu6Sn5 in a β-Sn matrix, but the micromorphology changed greatly. When 0.05 wt.% Ni-coated CNTs were added, the rod-shaped Cu6Sn5 particles disappeared, and all appeared in a form of dot-shaped Cu6Sn5 particles. DSC results showed only a slight decrease in the melting behavior of the composite solder. Experimental results unveiled that the addition of Ni-coated CNTs to Sn-0.7Cu solder could improve the wettability. With the addition of 0.05 wt.% Ni-coated CNTs, the wetting angle decreased by 13.35%, and an optimum wetting angle of 25.44° was achieved.

Medical Applications of Porous Biomaterials: Features of Porosity and Tissue-Specific Implications for Biocompatibility

Porosity is an important material feature commonly employed in implants and tissue scaffolds. The presence of material voids permits the infiltration of cells, mechanical compliance, and outward diffusion of pharmaceutical agents. Various studies have confirmed that porosity indeed promotes favorable tissue responses, including minimal fibrous encapsulation during the foreign body reaction (FBR). However, increased biofilm formation and calcification is also described to arise due to biomaterial porosity. Additionally, the relevance of host responses like the FBR, infection, calcification, and thrombosis are dependent on tissue location and specific tissue microenvironment. In this review, the features of porous materials and the implications of porosity in the context of medical devices is discussed. Common methods to create porous materials are also discussed, as well as the parameters that are used to tune pore features. Responses toward porous biomaterials are also reviewed, including the various stages of the FBR, hemocompatibility, biofilm formation, and calcification. Finally, these host responses are considered in tissue specific locations including the subcutis, bone, cardiovascular system, brain, eye, and female reproductive tract. The effects of porosity across the various tissues of the body is highlighted and the need to consider the tissue context when engineering biomaterials is emphasized.

Green hemostatic sponge-like scaffold composed of soy protein and chitin for the treatment of epistaxis

Epistaxis is one of the most common otorhinolaryngology emergencies worldwide. Although there are currently several treatments available, they present several disadvantages. This, in addition to the increasing social need of being environmentally respectful, led us to investigate whether a sponge-like scaffold (SP–CH) produced from natural by-products of the food industry — soy protein and β-chitin — can be employed as a nasal pack for the treatment of epistaxis. To evaluate the potential of our material as a nasal pack, it was compared with two of the most commonly used nasal packs in the clinic: a basic gauze and the gold standard Merocel®. Our SP-CH presented great physicochemical and mechanical properties, lost weight in aqueous medium, and could even partially degrade when incubated in blood. It was shown to be both biocompatible and hemocompatible in vitro, clearing up any doubt about its safety. It showed increased blood clotting capacity in vitro, as well as increased capacity to bind both red blood cells and platelets, compared to the standard gauze and Merocel®. Finally, a rat-tail amputation model revealed that our SP-CH could even reduce bleeding time in vivo. This work, carried out from a circular economy approach, demonstrates that a green strategy can be followed to manufacture nasal packs using valorized by-products of the food industry, with equal or even better hemostatic properties than the gold standard in the clinic.

3D-printable plant protein-enriched scaffolds for cultivated meat development

Cultivated meat harnesses tissue engineering (TE) concepts to create sustainable, edible muscle tissues, for addressing the rising meat product demands and their global consequences. As 3D-printing is a promising method for creating thick and complex structures, two plant-protein-enriched scaffolding compositions were primarily assessed in our work as 3D-printable platforms for bovine satellite cells (BSC) maturation. Mixtures of pea protein isolate (PPI) and soy protein isolate (SPI) with RGD-modified alginate (Alginate(RGD)) were evaluated as prefabricated mold-based and 3D-printed scaffolds for BSC cultivation, and ultimately, as potential bioinks for cellular printing. Mold-based protein enriched scaffolds exhibited elevated stability and stiffness compared to ones made of Alginate(RGD) alone, while allowing unhindered BSC spreading and maturation. Extrusion based 3D-printing with the two compositions was then developed, while using an edible, removable agar support bath. Successfully fabricated constructs with well-defined geometries supported BSC attachment and differentiation. Finally, cellular bioprinting was demonstrated with PPI-enriched bioinks. Cell recovery post-printing was observed in two cultivation configurations, reaching ∼80-90% viability over time. Moreover, cells could mature within 3D-printed cellular constructs. As animal-derived materials were avoided in our scaffold fabrication process, and pea-protein is known for its low allergic risk, these findings have great promise for further cultivated meat research.

A review on advancements in carbon quantum dots and their application in photovoltaics

Carbon quantum dots are a new frontier in the field of fluorescent nanomaterials, and they exhibit fascinating properties such as biocompatibility, low toxicity, eco-friendliness, good water solubility and photostability. In addition, the synthesis of these nanoparticles is facile, rapid, and satisfies green chemistry principles. CQDs have easily tunable optical properties and have found applications in bioimaging, nanomedicine, drug delivery, solar cells, light-emitting diodes, photocatalysis, electrocatalysis and other related areas. This article systematically reviews carbon quantum dot structure, their synthesis techniques, recent advancements, the effects of doping and surface engineering on their optical properties, and related photoluminescence models in detail. The challenges associated with these nanomaterials and their prospects are discussed, and special emphasis has been placed on the application of carbon quantum dots in enhancing the performance of photovoltaics and white light-emitting diodes.

This review puts forth the in-depth understanding of the fundamentals of carbon quantum dots(CQDs), recent advancements in the field including a thorough discussion on different roles of CQDs to enhance the performance of solar cells and white-LEDs.

Next step in 2nd generation glucose biosensors: Ferrocene-loaded electrospun nanofibers

Glucose determination is one of the most common analyses in clinical chemistry. Employing biosensors for this purpose has become the method of choice for home use for diabetic patients. To limit the impact of dissolved O₂ concentration or possible interferences (known hindrances in the classical glucose detection approach), a variety of mediated pathways have been explored. Herein, an ingenious, facile and low-cost approach for immobilization of redox mediator within nanofibrous mats is presented. This '2^nd generation' biosensor is able to avoid common issues such as leaching or diffusion barriers whilst providing the necessary close contact between the enzyme and the redox shuttle, for enhancing the detection accuracy and accelerate the response. Polyacrylonitrile nanofibers loaded with carbon nanotubes and ferrocene (PAN/Fc/MWCNT-COOH NFs) have been successfully prepared and applied as biosensing matrices upon cross-linking of glucose oxidase (GOD). The morphology of the NFs was investigated by means of scanning electron microscopy (SEM-EDX) and correlated to the kinetics of mediated electron transfer and to the efficiency in glucose detection, which were evaluated through cyclic voltammetry (CV) and amperometric measurements. The content of Fc was varied from 0.5 to 5.0 wt%, with optimum biosensor performance at 1.0 wt% exhibiting a linear range up to 8.0 × 10^-3 M with sensitivity of ~27.1 mAM^-1 cm^-2 and 4.0 μM LOD. Excellent stability (RSD 2.68%) during 40 consecutive measurements along with insignificant interference and accurate recovery in real sample analysis (~100%) make for a very reliable sensor that can easily render itself to miniaturization and has the potential for a wide range of practical applications.

Efficacy of fermentation parameters on protein quality and microstructural properties of processed finger millet flour

The present study aims to explore the outcome of processing methods such as fermentation; treatments using lemon juice (T1), sodium chloride (T2), lemon juice followed by sodium chloride (T3) and fermentation followed by treatment-T3 on the quality characteristics of processed finger millet flour to develop a specialized low protein food supplement for a protein-related inborn error of metabolic disorders. The clean dirt-free finger millet grains were made into slurry subjected to treatment T1 (FMFT1), T2 (FMFT2), T3 (FMFT3), fermentation for 8-36 h with 4 h intervals using yoghurt as starter culture (FFMF) and fermentation (8-36 h) followed by treatment T3 (FFMFT3). The acidity of the finger millet slurry significantly increased with the increase in fermentation time when compared to control. The IVPD was found to be 89% in FFMF (20 h) sample which was significantly higher than the IVPD of control sample flour (27%). However, the crude protein content (%), the protein fractions and the IVPD of FFMFT3 (8-36 h) samples were found to be lesser than the FFMF (8-36 h) samples. The findings were further ensured by the results of scanning electron microscopic images and FT-IR spectra which showed the morphological and chemical modifications caused by the processing methods. The setback and breakdown viscosity of control (945 cP and 664 cP respectively) approximately reduced to two-third in FFMF (20 h) samples and one-third for FFMFT3 samples (303 cP and 286 cP respectively). From the study, it is evident that the processing method of fermentation followed by treatment-T3 could be utilized in the development of low protein food supplements.

High-throughput fabrication of silk fibroin/hydroxypropyl methylcellulose (SF/HPMC) nanofibrous scaffolds for skin tissue engineering

Silk fibroin (SF) is a natural macromolecule material with good biocompatibility, which can be used to prepare a variety of biological materials. In this study, hydroxypropyl methylcellulose (HPMC) was applied to improve the properties of SF nanofibrous scaffolds (NFS) for skin tissue engineering applications. SF/HPMC NFS with varying weight ratios of SF: HPMC were prepared in batches by a modified free surface electrospinning. The effects of the varying weight ratio of SF: HPMC on the morphology, property and yield of SF/HPMC NFS were investigated. The results revealed that with the increase of HPMC contents, the hydrophilicity of SF/HPMC NFS would be improved, but the yield of that would decrease. Considering its effects on the morphology, property and yield of SF/HPMC NFS, the optimal weight ratio of SF: HPMC was 7:1. And SF/HPMC NFS with the weight ratio of 7:1 (SF/HPMC-7:1 NFS) had good mechanical property, hydrophilicity, porosity, swelling property and water vapor transmission rate (WVTR). In addition, the viability test results of human umbilical vein endothelial cells demonstrated that SF/HPMC-7:1 NFS maintained excellent biocompatibility for cell adhesion and proliferation.

Preparation of aligned nanofibers using parallel inductive-plates assisted electrospinning

Electrospinning is a simple, cost-effective, and versatile technique for fabrication of nanofibers. However, nanofibers obtained from the conventional electrospinning are typically disordered, which seriously limits their application. In this work, we present a novel and facile technique to obtain aligned nanofibers with high efficiency by using parallel inductive-plates assisted electrospinning (PIES). In this new electrospinning setup, the electrostatic spinneret is contained in a pair of parallel inductive-plates, which can change the shape and direction of the electric field line during the electrospinning so as to control the flight trajectory and spatial alignment of the spinning nanofibers. This electrospinning setup can divide the electric field line into two parts which are respectively directed to the edge of the upper and lower inductive-plates. Then the nanofibers move along the electric field line, suspend and align between the parallel inductive-plates. Finally, the well aligned nanofibers could be easily transferred onto other substrates for further characterizations and applications. The aligned nanofibers with an average diameter of 469 ± 115 nm and a length as long as 140 mm were successfully achieved by using PIES technique. Moreover, nanofiber arrays with different cross angles and three-dimensional films formed by the aligned nanofibers were also facilely obtained. The novel PIES developed in this work has been proved to be a facile, cost-effective and promising approach to prepare aligned nanofibers for a wide range of applications.

A Hydrogen-Bonded Extracellular Matrix-Mimicking Bactericidal Hydrogel with Radical Scavenging and Hemostatic Function for pH-Responsive Wound Healing Acceleration

Generation of reactive oxygen species, delayed blood clotting, prolonged inflammation, bacterial infection, and slow cell proliferation are the main challenges of effective wound repair. Herein, a multifunctional extracellular matrix-mimicking hydrogel is fabricated through abundant hydrogen bonding among the functional groups of gelatin and tannic acid (TA) as a green chemistry approach. The hydrogel shows adjustable physicochemical properties by altering the concentration of TA and it represents high safety features both in vitro and in vivo on fibroblasts, red blood cells, and mice organs. In addition to the merit of facile encapsulation of cell proliferation-inducing hydrophilic drugs, accelerated healing of skin injury is obtained through pH-dependent release of TA and its multifaceted mechanisms as an antibacterial, antioxidant, hemostatic, and anti-inflammatory moiety. The developed gelatin-TA (GelTA) hydrogel also shows an outstanding effect on the formation of extracellular matrix and wound closure in vivo via offered cell adhesion sites in the backbone of gelatin that provide increased re-epithelialization and better collagen deposition. These results suggest that the multifunctional GelTA hydrogel is a promising candidate for the clinical treatment of full-thickness wounds and further development of wound dressing materials that releases active agents in the neutral or slightly basic environment of infected nonhealing wounds.

Poly(vinylidenefluoride) polymers and copolymers as versatile hosts for luminescent solar concentrators: compositional tuning for enhanced performance

Novel host matrices based on fluoropolymers blended with poly(methyl methacrylate) (PMMA) are presented in this work for application in efficient and photochemically stable thin-film luminescent solar concentrators (LSCs). These systems consist of blends of PMMA with three different partially fluorinated polymers in different proportions: polyvinylidenefluoride homopolymer, a copolymer of vinylidenefluoride and chloro-trifluoro-ethylene, and a terpolymer of vinylidenefluoride, hexafluoropropylene and hydroxyl-ethyl acetate. A detailed chemical, physical and structural characterization of the obtained materials allowed us to shed light on the structure–property relationships underlying the response of such blends as a LSC component, revealing the effect of the degree of crystallinity of the polymers on their functional characteristics. An optimization study of the optical and photovoltaic (PV) performance of these fluoropolymer-based LSC systems was carried out by investigating the effect of blend chemical composition, luminophore concentration and film thickness on LSC device output. LSCs featuring copolymer/PMMA blends as the host matrix were found to outperform their homopolymer- and terpolymer-based blend counterparts, attaining efficiencies comparable to those of reference PMMA-based LSC/PV assemblies. All optimized LSC systems were subjected to weathering tests for over 1000 h of continuous light exposure to evaluate the effect of the host matrix system on LSC performance decline and to correlate chemical composition with photochemical durability. It was found that all fluoropolymer/PMMA-based LSCs outperformed reference PMMA-based LSCs in terms of long-term operational lifetime. This work provides the first demonstration of thermoplastic fluoropolymer/PMMA blends for application as host matrices in efficient and stable LSCs and widens the scope of high-performance thermoplastic materials for the PV field.

Novel fluoropolymer–polymethylmethacrylate blends used as host matrices in luminescent solar concentrators (LSCs) are presented. Fluoropolymer/PMMA-based LSC efficiency is comparable to that of PMMA-based LSCs and is stable over 1000 h of aging test.

Anion-dependent structural variations and charge transport property analysis of 4′-(3-pyridyl)-4,2′:6′,4′′-terpyridinium salts

Anion-dependent structural variations and charge transport analysis of three 4′-(3-pyridyl)-4,2′:6′,4′′-terpyridinium salts are reported. They exhibit pronounced photosensing behavior when illuminated using visible light.

Impact of multi-vinyl taxogen dimensions on high molecular weight soluble polymer synthesis using transfer-dominated branching radical telomerisation

The creation of branched polymers by TBRT is influenced by the molecular dimensions of the polymerising species. A mechanistic understanding is presented that includes a radical lifetime sphere model that is unique to telomerisation conditions used.

Effect of the in-plane aspect ratio of a graphene filler on anisotropic heat conduction in paraffin/graphene composites

Enhancement of polymer thermal conductivity using nanographene fillers and clarification of its molecular-scale mechanisms are of great concern in the development of advanced thermal management materials. In the present study, molecular dynamics simulation was employed to theoretically show that the in-plane aspect ratio of a graphene filler can have a significant impact on the effective thermal conductivity of paraffin/graphene composites. Our simulation included multiple graphene fillers aggregated in a paraffin matrix. The effective thermal conductivity of a paraffin/graphene composite, described as a second-rank tensor in the framework of equilibrium molecular dynamics simulation, was calculated for two types of graphene fillers with the same surface area but in-plane aspect ratios of 1 and 10. The filler with the higher aspect ratio was found to exhibit a much higher thermal conductivity enhancement than the one with the lower aspect ratio. This is because a high in-plane aspect ratio strongly restricts the orientation of fillers when they aggregate and, consequently, highly ordered agglomerates are formed. On decomposing the effective thermal conductivity tensor into various molecular-scale contributions, it was identified that the thermal conductivity enhancement is due to the increased amount of heat transfer inside the graphene filler, particularly along the longer in-plane axis. The present result indicates a possibility of designing the heat conduction characteristics of a nanocomposite by customizing the filler shapes so as to control the aggregation structure of the fillers.

Tea from the drinking to the synthesis of metal complexes and fabrication of PVA based polymer composites with controlled optical band gap

In the present study black tea extract (BTE) solution which is familiar for drinking was used to prepare cerium metal-complexes (Ce(III)-complex). The prepared Ce(III)-complex was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV–Vis spectroscopy. The results indicate that BTE solution is a novel green coordination chemistry approach for the synthesis of metal complexes. The outcomes signify that coordination occurs between cerium cations and polyphenols. The synthesis of metal-complexes with superior absorption performance in the visible region is a challenge for optoelectronic device applications. The suspended Ce(III)-complex in distilled water was mixed with poly (vinyl alcohol) (PVA) polymer to fabricate PVA/ Ce(III)-complex composites with controlled optical properties. The PVA/Ce(III)-complexes composite films were characterized by FTIR, XRD, and UV–Vis spectroscopy. The XRD findings confirms the amorphous structure for the synthesized Ce(III)-complexes. The addition of Ce(III)-complex into the PVA host polymer led to the growth of polymer composites with controllable small optical band gaps. It is shown by the FTIR spectra of the composite films that the functional groups of the host PVA have a vigorous interaction with the Ce(III)-complex. The XRD deconvolution on PVA composites reveals the amorphous phase enlargement with increasing Ce(III)-complex concentration. It is indicated in the atomic force microscopy (AFM) that the surface roughness in the doped PVA films increases with the increase of the Ce(III)-complex. There is a decrease in absorption edge from 5.7 to 1.7 eV. It becomes possible to recognize the type of electron transition by studying both the Tauc's model and optical dielectric loss (ɛ_i) parameter.

Control of Macromolecule Chains Structure in a Nanofiber

Mechanical property is one of the most important properties of nanofiber membranes. Electrospinning is widely used in the preparation of nanofibers due to its advantages such as good stability and easy operation. Compared with some nature silk, the mechanical properties of nanofibers prepared by electrospinning are poor. Based on the principle of vortex spinning and DNA structure, this paper designed an air vortex electrospinning device that can control the structure of macromolecular chains in nanofibers. When a weak air vortex is generated in the electrospinning process, the macromolecule chains will entangle with each other and form a DNA-like structure so as to improve the mechanical property. In addition, when a strong air vortex is generated during the electrospinning process, the nanofibers will adhere to each other, thereby enhancing the mechanical property and enlarging the pore size.

Structure and electrochemical performance of electrospun-ordered porous carbon/graphene composite nanofibers

Ordered carbon/graphene composite nanofibers (CGCNFs) with different porous configurations were used as a material to fabricate supercapacitor electrodes. These nanofibers were synthesized by applying a modified parallel electrode to the electrospinning method (MPEM) in order to generate electrospun polyacrylonitrile (PAN) nanofibers containing graphene. After synthesis, these fibers were submitted to carbonization under a N2 atmosphere at 1100 °C. The influence of the ordering and porosity of CGCNFs on their electrochemical performance was studied. The results showed that by adding deionized water to the spinning solution one could increase the number of mesopores and the specific surface area of CGCNFs, thereby significantly increasing their specific capacitance. In addition, the ordering of CGCNFs within the electrode improved the electron transfer efficiency, resulting in a higher specific capacitance.

A Nanofibrillated Cellulose-Based Electrothermal Aerogel Constructed with Carbon Nanotubes and Graphene

Nanofibrillated cellulose (NFC) as an environmentally friendly substrate material has superiority for flexible electrothermal composite, while there is currently no research on porous NFC based electrothermal aerogel. Therefore, this work used NFC as a skeleton, combined with multi-walled carbon nanotubes (MWCNTs) and graphene (GP), to prepare NFC/MWCNTs/GP aerogel (CCGA) via a simple and economic freeze-drying method. The electrothermal CCGA was finally assembled after connecting CCGA with electrodes. The results show that when the concentration of the NFC/MWCNTs/GP suspension was 5 mg mL^-1 and NFC amount was 80 wt.%, the maximum steady-state temperature rise of electrothermal CCGA at 3000 W m^-2 and 2000 W m^-2 was of about 62.0 °C and 40.4 °C, respectively. The resistance change rate of the CCGA was nearly 15% at the concentration of 7 mg mL^-1 under the power density of 2000 W m^-2. The formed three-dimensional porous structure is conducive to the heat exchange. Consequently, the electrothermal CCGA can be used as a potential lightweight substrate for efficient electrothermal devices.

Preparation, characterization and photocatalytic performance of heterostructured CuO-ZnO-loaded composite nanofiber membranes

Inorganic semiconductor oxides loaded on composite nanofibers (CNFs) have been widely applied in environmental monitoring, industry, aviation, and transportation. In this paper, heterostructured CuO-ZnO-loaded CNF membranes (CNFMs) were prepared successfully by a combination of electrospinning, heat treatment, and hydrothermal synthesis. The influence of the synthesis parameters on morphology, structure, and properties of the CNFMs was investigated, and the optimal process parameters were determined. Then, the CNFMs obtained with optimal process parameters were applied for the photocatalytic degradation of methyl orange. It was found that the CNFMs could be reused to degrade methyl orange at least three times, and the degradation rate remained above 90%.

Investigation of alkaline hydrogen peroxide pretreatment to enhance enzymatic hydrolysis and phenolic compounds of oil palm trunk

Alkaline hydrogen peroxide (AHP) as a pretreatment effectively enhances the increasing enzymatic digestibility of oil palm trunk (OPT) for conversion to biofuels and bioproducts in the biorefinery processes. The effect of hydrogen peroxide concentration (1-5%), temperature (50-90 °C), and time (30-90 min) were studied to find out the optimum condition for the removal of lignin. The optimum condition attained at 70 °C, 30 min, and 3% H₂O₂ g /g of biomass not only increased the cellulose content from 38.67% in raw material to 73.96% but also removed lignin and hemicellulose up to 50% and 57.12%, respectively. The AHP-treated fibers subjected to enzyme hydrolysis showed significant improvement in glucose concentration that increased from 11.77 (± 0.84) g/L (raw material) to 46.15 (± 0.32) g/L with 59.82% enzyme digestibility at 96 h. Scanning electron microscopy (SEM) and Fourier transformation infrared (FT-IR) were employed to analyze the morphology and structural changes of untreated and AHP-treated fibers. SEM results showed disruption of the intact OPT structure resulting in increase of enzyme accessibility to cellulose. The FT-IR identified changes in peaks which indicated structural transformation and dissolution of both lignin and hemicellulose molecules caused by AHP treatment. The black liquor obtained from AHP treatment contained about 5.13 mg gallic acid equivalent (GAE)/g of dry sample of total phenolic content (TPC) and an antioxidant activity of 59.80% and 65.51% inhibitions of DPPH and ABTS assays, respectively. Hence, it is a sustainable approach to utilize waste for the recovery of multiple value-added products during pretreatment process.

Effect of surface interactions on the settlement of particles on a sinusoidally corrugated substrate

Naturally-occurring surface topographies abound in nature and endow diverse properties, i.e., superhydrophobicity, adhesion, anti-fouling, self-cleaning, anti-glare, anti-bacterial, and many others. Researchers have attempted to replicate such topographies to create human-made surfaces with desired functionalities. For example, combining the surface topography with judicial chemical composition could provide an effective, non-toxic solution to combat non-specific biofouling. A systematic look at the effect of geometry, modulus, and chemistry on adhesion is warranted. In this work, we use a model system that comprises silica (SiO x ) beads interacting with a substrate made of a commercial polydimethylsiloxane kit (PDMS, Sylgard 184) featuring a sinusoidal topography. To examine the impact of interactions on particle settlement, we functionalize the surfaces of both the PDMS substrate and the SiO x beads with polyacrylic acid (PAA) and polyethyleneimine (PEI), respectively. We also use the PDMS commercial kit coated with liquid glass (LG) to study the effect of the substrate modulus on particle settlement. Substrates with a higher aspect ratio (i.e., amplitude/periodicity) encourage adsorption of particles along the sides of the channel compared with substrates with lower aspect ratio. We employ colloidal probe microscopy to demonstrate the effect of interaction between the substrate and the particle. The interplay among the surface modulus, geometry, and interactions between the surface and the particle governs particle settlement on sinusoidally-corrugated substrates.

Mechanisms of mechanical reinforcement by graphene and carbon nanotubes in polymer nanocomposites

Polymer nanocomposites reinforced with carbon-based nanofillers are gaining increasing interest for a number of applications due to their excellent properties. The understanding of the reinforcing mechanisms is, therefore, very important for the maximization of performance. This present review summarizes the current literature status on the mechanical properties of composites reinforced with graphene-related materials (GRMs) and carbon nanotubes (CNTs) and identifies the parameters that clearly affect the mechanical properties of the final materials. It is also shown how Raman spectroscopy can be utilized for the understanding of the stress transfer efficiency from the matrix to the reinforcement and it can even be used to map stress and strain in graphene. Importantly, it is demonstrated clearly that continuum micromechanics that was initially developed for fibre-reinforced composites is still applicable at the nanoscale for both GRMs and CNTs. Finally, current problems and future perspectives are discussed.