直立碳纳米管超级电容器的研究

在石英玻璃基底上,以酞菁裂解法低压气相沉积制备大面积管径均匀、长度一致的直立碳纳米管.分别应用电解质溶液浸润、酸处理和循环伏安扫描等3种不同方法纯化活化该直立碳纳米管,并以活化后的碳纳米管作为原型超级电容器的电极.循环伏安扫描和交流阻抗测试表明,CV曲线呈近似矩形,交流阻抗最大相位角超过80°,该直立碳纳米管的比电容为16~32F/g,乃超级电容器理想的电极材料.     

Advances in Fibrin-Based Materials in Wound Repair: A Review

The first bioprocess that occurs in response to wounding is the deterrence of local hemorrhage. This is accomplished by platelet aggregation and initiation of the hemostasis cascade. The resulting blood clot immediately enables the cessation of bleeding and then functions as a provisional matrix for wound healing, which begins a few days after injury. Here, fibrinogen and fibrin fibers are the key players, because they literally serve as scaffolds for tissue regeneration and promote the migration of cells, as well as the ingrowth of tissues. Fibrin is also an important modulator of healing and a host defense system against microbes that effectively maintains incoming leukocytes and acts as reservoir for growth factors. This review presents recent advances in the understanding and applications of fibrin and fibrin-fiber-incorporated biomedical materials applied to wound healing and subsequent tissue repair. It also discusses how fibrin-based materials function through several wound healing stages including physical barrier formation, the entrapment of bacteria, drug and cell delivery, and eventual degradation. Pure fibrin is not mechanically strong and stable enough to act as a singular wound repair material. To alleviate this problem, this paper will demonstrate recent advances in the modification of fibrin with next-generation materials exhibiting enhanced stability and medical efficacy, along with a detailed look at the mechanical properties of fibrin and fibrin-laden materials. Specifically, fibrin-based nanocomposites and their role in wound repair, sustained drug release, cell delivery to wound sites, skin reconstruction, and biomedical applications of drug-loaded fibrin-based materials will be demonstrated and discussed.     

Oil-Water Separation Performance of Electrospray Reduced Graphene Oxide Microspheres with a Local Radially Aligned and Porous Structure

Micro-size oil adsorbents are effective for the rapid remediation of special oil spills. Here, N-doped reduced graphene oxide(RGO) microspheres(ca. 150 μm in diameter) with a local radially aligned and porous structure are fabricated by combining electrospray-freeze-drying with thermal treatment for rapid separation of oil-water. Owing to its hydrophobic/oleophilic properties and oriented structure, the N-doped RGO microspheres achieve high capacities and fast adsorption rates for a variety of oils and organic solvents. Furthermore, excellent oil-water separation performance on floating oil/oil-water emulsions and stable cyclic adsorption capacities are obtained for the local radially aligned and porous microsphere. Therefore, N-doped RGO microspheres with the unique porous structure have the potential for the remediation of oily sewage and oil spills.     

Cellulose Nanofibers from Schinus molle: Preparation and Characterization

Schinus molle (SM) was investigated as a primary source of cellulose with the aim of discovering resources to generate cellulose nanofibers (CNF). The SM was put through a soda pulping process to purify the cellulose, and then, the fiber was treated with an enzymatic treatment. Then, a twin-screw extruder and/or masuko were utilized to help with fiber delamination during the nanofibrillation process. After the enzymatic treatment, the twin-screw extruder and masuko treatment give a yield of 49.6 and 50.2%, respectively. The optical and atomic force microscopy, morfi, and polymerization degrees of prepared cellulosic materials were established. The pulp fibers, collected following each treatment stage, demonstrated that fiber characteristics such as length and crystallinity varied according to the used treatment (mechanical or enzymatic treatment). Obviously, the enzymic treatment resulted in shorter fibers and an increased degree of polymerization. However, the CNF obtained after enzymatic and extrusion treatment was achieved, and it gave 19 nm as the arithmetic width and a Young’s modulus of 8.63 GPa.     

Multifunctional edible chitin nanofibers/ferulic acid composite coating for fruit preservation

About one-third of the world's entire food production is lost or wasted every year, in which the perishables such as fruits and vegetables account for the largest proportion due to their short shelf life. Therefore, it has attracted great attention to the development of food preservation. In this paper, a simple strategy for food preservation is developed. Chitin nanofiber aqueous suspension is used as the substrate, and ferulic acid (FA) acts as the physical crosslinker to obtain a multifunctional composite protective coating for fruits. The results of Zeta potential, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) indicate that there are multiple noncovalent interactions between FA and chitin nanofibers. The chitin/FA coating films show superior mechanical properties, water and oxygen resistance. They could effectively reduce the water loss rate, delay ripening, and resist oxidation and microbial invasion for the fresh strawberries and fresh-cut apples, indicating the potential in food preservation.     

Dual-Function Fibrous Co-Polypeptide Scaffolds for Neural Tissue Engineering

This paper reports dual-function (high cell attachment and cell viability) fibrous scaffolds featuring aligned fibers, displaying good biocompatibility and no cytotoxicity. These scaffolds are fabricated through the electrospinning of a co-polypeptide comprising molar equivalents of N₆-carbobenzyloxy-l -lysine and γ-benzyl-l -glutamate, with the lysine moieties enhancing cell adhesion and the neural-stimulating glutamate moieties improving cell viability. These new scaffolds allow neural cells to attach and grow effectively without any special surface treatment or coating. Pheochromocytoma (PC-12) cells grown on these scaffolds exhibit better neuronal activity and longer neurite length, relative to those grown on scaffolds prepared from their respective homo-polypeptides. When the scaffolds are partially hydrolyzed such that they present net positive charge and increased hydrophilicity, the cell viability and neurite growth both increase further. Accordingly, these novel co-polypeptide fibrous scaffolds have potential applications in neural tissue engineering.     

Nanofibers as optical sensors for model VOCs dispersed in aqueous phase

Nanofibers mats, prepared from poly(vinyl chloride) (PVC) containing dispersed dye Nile red (NR) were applied in a proof of concept study as optical sensors for Volatile Organic Compounds (VOCs) dispersed in an aqueous phase. Benefiting from the solubility of the dye, and in some cases, also of the polymer in model solvents belonging to the group of VOCs, an increase of emission was observed for increasing solvent concentration in the sample. The optical signal formation was observed regardless if only the dye or both dye and PVC were soluble in the tested solvent. In both cases, high sensitivity emission increases for increasing VOCs present in the aqueous phase were observed within the range of concentration of model analytes: from 200 ppm of m-xylene or from 300 ppm of styrene, to up to ca 1500 ppm. The obtained higher detection limit was lower compared to films of PVC containing the dye due to the lower availability of the material to be dissolved by analyte – solvent. The large surface area of nanofibers was useful in the detection, leading to higher signal changes compared to films.     

Determination of polyamines in urine via electrospun nanofibers–based solid-phase extraction coupled with GC-MS and application to gastric cancer patients

The simultaneous determination of polyamines and their metabolites in urine samples was achieved by gas chromatography–mass spectrometry in the selected ion monitoring mode. After conjugating with the ion-pair reagent bis-2-ethylhexylphosphate in the aqueous phase, the polyamines in the samples were extracted with polystyrene nanofiber-based packed-fiber solid-phase extraction followed by a derivatization step using pentafluoropropionyl anhydride. With optimal conditions, all analytes were separated well. For analytes of putrescine, cadaverine, N-acetylputrescine, and N-acetylcadaverine, the linearity was good in the range of 0.05–500 μmol/L (R² ≥ 0.993). While for spermidine, spermine, acetylspermidine, N⁸-acetylspermidine, and N-acetylspermine, the linearity was good in the range of 0.5–500 μmol/L (R² ≥ 0.990). The recoveries of three spiked concentrations (0.5, 5, 300 μmol/L) were 85.6%–108.4%, and relative standard deviations for intra- and interday were in the range of 2.9%–13.4% and 4.5%–15.1%, respectively. The method was successfully applied to the analysis of urine samples of gastric cancer patients. The results showed that the levels of most polyamines and N-acetylated polyamines from the patient group were significantly higher than those from the control group. The altered concentrations of the above-mentioned metabolites suggest their role in the pathogenesis of gastric cancer, and they should be further evaluated as potential markers of gastric cancer.     

Effects of ultrasonic-assisted pH shift treatment on physicochemical properties of electrospinning nanofibers made from rapeseed protein isolates

Electrospinning nanofibers (NFs) made from natural proteins have drawn increasing attention recently. Rapeseed meal is a by-product that rich in protein but not fully utilized due to poor properties. Therefore, modification of rapeseed protein isolates (RPI) is necessary to expand applications. In this study, pH shift alone or ultrasonic-assisted pH shift treatment was adopted, the solubility of RPI, along with the conductivity and viscosity of the electrospinning solution were detected. Moreover, the microstructure and functional characteristics of the electrospinning NFs, as well as the antibacterial activity of clove essential oil loaded-NFs were investigated. The tested parameters were remarkably improved after different treatments compared with the control, and synergistic effects were observed, especially under alkaline conditions. Hence, pH_12.5 + US showed the maximum value of solubility, conductivity, and viscosity, which was more than 7-fold, 3-fold, and almost 1-fold higher than the control respectively. Additionally, SEM and AFM images showed a finer and smoother surface of NFs after treatments, and the finest diameter of 216.7 nm was obtained after pH_12.5 + US treatment in comparison with 450.0 nm in control. FTIR spectroscopy of NFs demonstrated spatial structure changes of RPI, and improved thermal stability and mechanical strength of NFs were achieved after different treatments. Furthermore, an inhibition zone with a diameter of 22.8 mm was observed from the composite NFs. This study indicated the effectiveness of ultrasonic-assisted pH shift treatment on the physicochemical properties improvement and functional enhancement of NFs made from RPI, as well as the potential antibacterial application of the composite NFs in the future.     

Synthesis and properties of PbGeO3 nanostructures

PbGeO₃ nanostructures including nanofibers and nanobelts, have been synthesized via a facile hydrothermal method by the reaction between GeO₂ and Pb(CH₃COO)₂·3H₂O in the absence of any surfactant. The influences of synthetic parameters, such as reaction time, reaction temperature, and the concentration of ethylenediamine, on the morphologies and sizes of PbGeO₃ nanostructures have been investigated. It is found that an evolution of PbGeO₃ nanostructures from nanobelts to nanofibers is observed for the first time with the reaction time increased from 1 h to 6 h. The diameters of PbGeO₃ nanofibers can be controled from 300–900 nm to 80–120 nm by adjusting the concentration of ethylenediamine. Under similar conditions, PbGeO₃: Eu³⁺ nanofibers with rough surfaces can also be obtained. The photoluminescent spectra of PbGeO₃: Eu³⁺ nanofibers exhibits two fluorescence emission peaks centered at around 591 and 614 nm as the excitation wavelength is 395 nm. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)