2016, Vol. 1, No. 4
China has become a leading powerhouse in global research community. The boom of scientific and technical papers published by Chinese researchers in terms of both quantity and quality has been well received. However, concerns have been raised on current publication drives.
Microfibrillated cellulose (MFC)-collagen composite films were prepared with a dispersion of acid swollen collagen fibers and carboxylated MFC at different ratios in an alkaline homogenous system. The surface topographic results obtained from SEM analyses indicated that the MFC entangled uniformly with collagen in the film and formed a closely interwoven network to reinforce the film structure. However, the MFC addition decreased the smoothness and light transparency of the films due to the aggregation of MFC. Compared to the film prepared with pure collagen, the hybrid composite film showed a higher strength and Young's modulus but lower elongation. The swelling of the composite film in water increased with the increase of the MFC ratio in the film matrix. DSC and TG analyses demonstrated that adding MFC to collagen benefited the thermal stability of the films, due to the conformational and crystal changes in the MFC/collagen structure indicated by the FT-IR and XRD results. The MFC/collagen composite film can potentially be used as an edible material in the food and packaging industry, in particular for meat products.
The upsurge in the prevalence of side effects of many synthetic antimicrobial agents and incidence of multidrug resistant bacteria has spurred scientists on the search for plant based antimicrobial of therapeutic potentials. The study extracted essential oils from the flowers of Tithonia diversifolia (Hemsl) A. Gray (Mexican sunflower) and assayed it for antimicrobial activities. The oils were extracted (hydro-distillation), characterized (GC-MS) and tested for antibacterial and antifungal activities. α-Pinene (34.42%), β-Caryophyllene (22.34%), β-Pinene (11.14%), Germacrene-D (11.13%) and 1, 8-Cineole (8.76%) were the major constituents of the forty-five compounds characterized. The characterized compounds were general monoterpenes (44.44%), sesquiterpenes (26.67%), including alcohols and aldehydes which accounted for 28.89%. The extract concentrations of 8-120 mg/ml in Potato Dextrose Agar (PDA) medium effectively inhibited the tested fungi in vitro. At 5 mg/ml, only Bacillus megaterium and Bacillus cereus were inhibited of all gram-positive bacteria while Streptococcus pyrogens was unaffected. All gram-negative bacteria were inhibited. Growth inhibition of the gram-positive and gram-negative species increases with increased concentration of the essential oil. At 40 mg/ml, all the tested bacteria species were inhibited and the growth inhibition for the species followed the order; E. coli> Proteus mirabi> Bacillus megaterium> Klebsiella pneumonia> Bacillus cereus> Streptococcuspyrogens. The oil concentration of 72 mg/ml totally inhibited the growth of all three fungal species-Cochliobolus lunatus, Fusarium solani, Fusarium lateritum. The secondary metabolites in the oil of T. diversifolia proved effective against the tested bacteria and fungi species. The finding of this study unlocks the potentials of this essential oil of Mexican sunflower for bio-pesticide production.
Basil (Ocimum basilicum), an edible and medicinal plant with high nutritional value and therapeutic efficacy, was used as a potential source of total flavonoids in this study. Heat reflux extractions were performed using aqueous ethanol. The optimized extraction conditions of total flavonoids from O. basilicum were determined by Box-Behnken design with response surface methodology. Response surface plots showed that the optional four independent variables significantly influenced the extraction yield of total flavonoids. The extraction parameters for the highest total flavonoids yield were optimized as:extraction temperature of 79.74℃, ethanol concentration of 77.63%, ratio of liquid to material of 29.72:1 (mL/g), and extraction time of 2.06 h. The average yield of total flavonoids under above optimum parameters was 42.61 mg of rutin equivalents per g of extract dry matter, which was in good agreement with the predicted value of 40.23 mg/g. These optimized conditions could be useful for the extraction of flavonoids from O. basilicum.
The performance of nano-cellulose fluid as a "green" flooding agent in enhancing oil recovery was evaluated in our previous study. Expanding upon our prior findings, in this study the physical properties of nano-cellulose were further improved through chemical grafting with 2-acrylamido-2-methylpropane sulfonic acid monomer (AMPS) and alkyl chain. Scanning electron microscopy (SEM) observation indicated that the morphology of the nano-cellulose maintained fibrillar and was not altered after the chemical modification. The thermal stability of the AMPS and alkyl chain grafted nano-cellulose was investigated through thermogravimetric analysis (TGA). A similar thermal response behavior was observed for the three evaluated samples. Compared to the non-grafted nano-cellulose, the grafted nano-cellulose remained homogenous in an electrolyte solution against storage time, suggesting a superior sanity-tolerance. Rheological analysis also proved the advanced viscoelastic properties of the nano-cellulose dispersion.
TiO2 nanoparticle is the most extensively used photocatalyst for photocatalytic paper. However, TiO2 nanoparticle is active only under UV light that accounted for less than 5% of the solar light energy. There is a need to develop a photocatalytic paper with full spectrum photoactivity. Herein, a full spectrum photocatalytic paper was fabricated by incorporating cellulose fibers with graphite fibers which were pre-loaded with Ag2O nanoparticles. X-ray diffraction (XRD) testing and scanning electron microscopy (SEM) examination confirmed the loading of the Ag2O nanoparticles onto the graphite fibers. The photocatalytic activity of the paper was evaluated with the degradation of methyl orange (MO) under ultraviolet, visible or near-infrared light irradiation. It was found that the degradation rate of MO could reach 32%, 19% and 19% under UV, visible and NIR light, respectively after 3 h of irradiation. Meanwhile, the photocatalytic paper was very stable and can be reused repeatedly. Antibacterial tests showed that the photocatalytic paper could inhibit Escherichia coli (E. coli) growth under office lighting condition.
This paper examined different kinds of organic functional groups that were introduced onto the surface of nano TiO2 by surface modification with different types of zircoaluminate coupling agents. The modified nanoTiO2 products with different interfacial properties were obtained, and the impact of the interfacial properties of nanoTiO2 on the rheological behavior of paper coating and the properties of coated paper was systematically investigated. The steady shear rheological results showed that the paper coatings containing nano TiO2 exhibited a pseudoplastic fluid behavior, characterized as obvious shear thinning. Compared to the hydrophilic unmodified nano TiO2, modified nano TiO2 could contribute more to the viscosity of paper coatings. The study on the dynamic viscoelasticity revealed that, through the enhancing action among each component in paper coatings, the modified nano TiO2 with quaternary amine groups or carboxyl led to a higher dynamic elastic storage modulus and viscous loss modulus of paper coatings. In addition, SEM and AFM analyses indicated that adding modified nano TiO2 products in paper coating could improve the coating structure, thus ameliorating the optical properties and printability of coated paper. The results obtained could provide a good reference for the application of nano pigments in paper coating.
Cellulose, as the most abundant natural biopolymers in the world, has attracted much attention in recent years, as concerns have been raised on environmental issues associated with the use of petroleum related products. Nano crystalline cellulose (NCC) is a special type of cellulose that is derived from renewable and sustainable resources such as cotton and wood. NCC has a large specific surface area with plentiful hydroxyl and anionic sulfate ester groups, which make NCC a perfect substrate for preparing composite absorbing and/catalytic materials for wastewater treatment. This paper reviews recent research on the applications of NCC in wastewater treatment.
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