Controlled Release of Volatile Antimicrobial Compounds from Mesoporous Silica Nanocarriers for Active Food Packaging Applications

Essential oils and their active components have been extensively reported in the literature for their efficient antimicrobial, antioxidant and antifungal properties. However, the sensitivity of these volatile compounds towards heat, oxygen and light limits their usage in real food packaging applications. The encapsulation of these compounds into inorganic nanocarriers, such as nanoclays, has been shown to prolong the release and protect the compounds from harsh processing conditions. Nevertheless, these systems have limited shelf stability, and the release is of limited control. Thus, this study presents a mesoporous silica nanocarrier with a high surface area and well-ordered protective pore structure for loading large amounts of natural active compounds (up to 500 mg/g). The presented loaded nanocarriers are shelf-stable with a very slow initial release which levels out at 50% retention of the encapsulated compounds after 2 months. By the addition of simulated drip-loss from chicken, the release of the compounds is activated and gives an antimicrobial effect, which is demonstrated on the foodborne spoilage bacteria Brochothrix thermosphacta and the potentially pathogenic bacteria Escherichia coli. When the release of the active compounds is activated, a ≥4-log reduction in the growth of B. thermosphacta and a 2-log reduction of E. coli is obtained, after only one hour of incubation. During the same one-hour incubation period the dry nanocarriers gave a negligible inhibitory effect. By using the proposed nanocarrier system, which is activated by the food product itself, increased availability of the natural antimicrobial compounds is expected, with a subsequent controlled antimicrobial effect.     

流态化技术在食品工业中的应用

介绍了脉动流化床、吸附流化床、离心流化床和热泵流化床在食品加工中的应用。通过与传统流化床进行比较分析。上述流化床能降低能源消耗、提高产品质量、减少营养成分的损失,使产品保持原来的风味。     

Allelopathic potential of sorghum (Sorghum bicolor)

The major inhibitory components obtained after fractionation of an aqueous extract of field-grown sorghum (Sorghumbicolorcv. Bird-a-boo) herbage were quantified in terms of biological potency by indexing three aspects of cumulative cress (Lepidium sativum cv. Curlycress) seed germination. The inhibitory potential expressed in the crude aqueous extract reflected a complex interaction of numerous individual components of diverse chemical compositions and potencies. Some of these inhibitory components included chemical classes not previously associated with herbage phytotoxicity.     

Studies of Cannabis sativa and Sorghum bicolor Oils

The white/red variety of Sorghum bicolor and Cannabis sativa of the family Moraeeae contains oil 2.8%, 2.7% and 33.3% respectively under the process of solvent extraction. The low percentage 2.1%. 1.2% and IK.7% of linolcnic acid as compared to high percentage of linoleic acid 46.3%. 46.7% and 46.8% in these oils classify them as semi-drying oils and therefore they can be used for edible purposes after their refining, bleaching, and deodorization. They can also be utilized in the manufacturing of margarine and shortenings after the hydrogenation of the oils.     

Synthesis of Densely Immobilized Gold-Assembled Silica Nanostructures

In this study, dense gold-assembled SiO₂ nanostructure (SiO₂@Au) was successfully developed using the Au seed-mediated growth. First, SiO₂ (150 nm) was prepared, modified by amino groups, and incubated by gold nanoparticles (ca. 3 nm Au metal nanoparticles (NPs)) to immobilize Au NPs to SiO₂ surface. Then, Au NPs were grown on the prepared SiO₂@Au seed by reducing chloroauric acid (HAuCl₄₎ by ascorbic acid (AA) in the presence of polyvinylpyrrolidone (PVP). The presence of bigger (ca. 20 nm) Au NPs on the SiO₂ surface was confirmed by transmittance electronic microscopy (TEM) images, color changes to dark blue, and UV-vis spectra broadening in the range of 450 to 750 nm. The SiO₂@Au nanostructure showed several advantages compared to the hydrofluoric acid (HF)-treated SiO₂@Au, such as easy separation, surface modification stability by 11-mercaptopundecanoic acid (R-COOH), 11-mercapto-1-undecanol (R-OH), and 1-undecanethiol (R-CH₃), and a better peroxidase-like catalysis activity for 5,5′-Tetramethylbenzidine (TMB) and hydrogen peroxide (H₂O₂) reaction. The catalytic activity of SiO₂@Au was two times better than that of HF-treated SiO₂@Au. When SiO₂@Au nanostructure was used as a surface enhanced Raman scattering (SERS) substrate, the signal of 4-aminophenol (4-ATP) on the surface of SiO₂@Au was also stronger than that of HF-treated SiO₂@Au. This study provides a potential method for nanoparticle preparation which can be replaced for Au NPs in further research and development.     

A Simplified Method for Fractionation and Analysis of Waxes and Oils from Sorghum (Sorghum bicolor (L.) Moench) Bran

In the United States, sorghum is primarily used for animal feed and ethanol production but has potential to provide value-added coproducts including waxes and oil. The surface of sorghum contains 0.1–0.4% wax; however, wax extraction from whole kernels before fermentation may not be economical. An alternative method for this extraction could be facilitated through decortication, abrasion of the surface to remove bran. Decortication increases the starch content of decorticated sorghum, potentially improving ethanol yields, while concentrating wax and oil to the bran. Typically, oil (triacylglycerols) and waxes are extracted from bran in one extraction and waxes are precipitated from oil using cold temperatures then filtration. This research compared traditional fractionation (simulated with a two-step, single-temperature extraction) to a two-step, dual-temperature extraction, whereby oil is first extracted at room temperature and then waxes at elevated temperature. Extractions were performed using an accelerated solvent extractor with hexane or ethanol as solvents. Ethanol extraction showed greater yields (~15% w/w) compared to those of hexane (~11% w/w) because polar materials were extracted. Using hexane, the two-step, dual-temperature fractionation separated waxes from oils via the temperature of extraction solvent with similar purity to the traditional method that fractionated via cold precipitation and filtration. For ethanol, the traditional single-step method fractionated with higher wax purity but lower oil purity compared to the two-step, dual-temperature fractionation.     

Controls on the Recycling and Preservation of Biogenic Silica from Biomineralization to Burial

The recycling of biogenic silica (bSiO₂) produced by diatoms is a vital process sustaining a significant fraction of primary production in the oceans. The efficiency with which bSiO₂ dissolves controls the availability of nutrient silicon in the water column, and modulates the export of organic carbon to the deep sea. Environmental conditions during biomineralization (temperature, nutrient availability, light, etc.) affect the silicification and weathering resistance of diatom frustules, while ecosystem processes, including grazing and aggregation, are determining factors for the recycling of bSiO₂ in the water column. Bacterial colonization of dead diatoms leads to the decomposition of the protective organic layers allowing for the dissolution of bSiO₂ to begin. The dissolution rate of diatom frustules is a function of the physicochemical properties of both the silica (e.g., specific surface area, degree of hydration and condensation, impurities) and the aqueous medium (e.g., temperature, pH, pressure, electrolyte composition). In sediments, the dissolution of bSiO₂ is controlled by the presence of lithogenic minerals, aging processes and the build up of dSi in the pore waters. In particular, interactions between lithogenic silicate minerals and bSiO₂ may initiate rapid diagenetic alterations that favor the preservation of bSiO₂.     

生物源农药市场及应用

介绍了全球主要生物源农药的市场和应用情况,以及最新产品的应用前景。     

Applications of Insect-Derived Protein Ingredients in Food and Feed Industry

The need for novel and diverse sources of protein to feed the growing world population is urgent and stark. At the same time, peoples’ eating habits and values are also changing, with more consumers considering alternatives to traditional sources of protein. Novel protein sources not only need to provide essential amino acids and nutrition, but also cater to taste, convenience, cost economics, and personal needs. They also need to be ethically produced, with a smaller environmental footprint, and when feasible, closer to consumer. Insect protein has been researched intensively in recent years with promises to best fulfill these needs. As the insect protein field and industry are expanding and getting more mature at this stage, this review summarizes their properties and applications within the context of the food and feed industry. The important functional properties that make insect proteins useful are also discussed.     

利用工业废渣生产瓷质外墙砖的研究

1 前 言 目前世界各地的工业和生活废渣越来越多,据资料统计,1997年主要工业国家的生活废渣达到5亿吨以上,而工业废渣是生活废渣的30倍以上。我国正处于大力发展经济的时期,工业生产与人民生活也产生了越来越多的废渣,传统的场地填埋及压实填埋已经不再合适用来处理日益增加的工业及生活废渣,这些废渣在不断侵蚀着人类本来有限的生存空间。如何科学合理地处理这些数量和体积同样庞大的工业和生活废渣,成为世界各国共同关注的问题。 陶瓷墙地砖作为美观大方经久耐用建筑饰材,越来越受人们喜爱。利用工业和生活废渣生产陶瓷墙地砖,不…     

Growth of Comb-like ZnO Nanostructures for Dye-sensitized Solar Cells Applications

Dye-sensitized solar cells (DSSCs) were fabricated by using well-crystallized ZnO nanocombs directly grown onto the fluorine-doped tin oxide (FTO) via noncatalytic thermal evaporation process. The thin films of as-grown ZnO nanocombs were used as photoanode materials to fabricate the DSSCs, which exhibited an overall light to electricity conversion efficiency of 0.68% with a fill factor of 34%, short-circuit current of 3.14 mA/cm², and open-circuit voltage of 0.671 V. To the best of our knowledge, this is first report in which thin film of ZnO nanocombs was used as photoanode materials to fabricate the DSSCs.     

石英陶瓷的应用

介绍了石英陶瓷在玻璃行业以外，冶金、化工、航空航天等领域的应用，包括应用的石英陶瓷制品、应用特点及条件。     

固定化纤维素酶及其在食品中的应用研究

固定化纤维素酶因其良好的稳定性和可重复使用性在许多领域得到广泛的应用,因此也成为广大科学工作者的研究热点之一。文章介绍了固定化纤维素酶的定义、研究现状、常用载体及其在食品工业中的应用,并指出了固定化纤维素酶发展方向,旨在为今后的深入研究提供理论指导。     

Fabrication of Large Area Periodic Nanostructures Using Nanosphere Photolithography

Large area periodic nanostructures exhibit unique optical and electronic properties and have found many applications, such as photonic band-gap materials, high dense data storage, and photonic devices. We have developed a maskless photolithography method—Nanosphere Photolithography (NSP)—to produce a large area of uniform nanopatterns in the photoresist utilizing the silica micro-spheres to focus UV light. Here, we will extend the idea to fabricate metallic nanostructures using the NSP method. We produced large areas of periodic uniform nanohole array perforated in different metallic films, such as gold and aluminum. The diameters of these nanoholes are much smaller than the wavelength of UV light used and they are very uniformly distributed. The method introduced here inherently has both the advantages of photolithography and self-assembled methods. Besides, it also generates very uniform repetitive nanopatterns because the focused beam waist is almost unchanged with different sphere sizes.     

Silicon and Germanium Nanostructures for Photovoltaic Applications: Ab-Initio Results

Actually, most of the electric energy is being produced by fossil fuels and great is the search for viable alternatives. The most appealing and promising technology is photovoltaics. It will become truly mainstream when its cost will be comparable to other energy sources. One way is to significantly enhance device efficiencies, for example by increasing the number of band gaps in multijunction solar cells or by favoring charge separation in the devices. This can be done by using cells based on nanostructured semiconductors. In this paper, we will present ab-initio results of the structural, electronic and optical properties of (1) silicon and germanium nanoparticles embedded in wide band gap materials and (2) mixed silicon-germanium nanowires. We show that theory can help in understanding the microscopic processes important for devices performances. In particular, we calculated for embedded Si and Ge nanoparticles the dependence of the absorption threshold on size and oxidation, the role of crystallinity and, in some cases, the recombination rates, and we demonstrated that in the case of mixed nanowires, those with a clear interface between Si and Ge show not only a reduced quantum confinement effect but display also a natural geometrical separation between electron and hole.     

Mesoporous Silica–Zirconia Systems for Catalytic Applications

In this study synthesis and characterization of solid acid catalysts with definite textural properties (high surface area, narrow pore size dimension, ordered structure) are described. In particular sulphated zirconia (SZ) has been introduced on three ordered mesoporous silica, MCM-41, MCM-48 and SBA-15, in order to study the influence of silica supports on textural and chemical–physical properties of final catalysts. The correlation between the catalytic behavior of SZ supported samples and their textural and chemical physical properties was studied in the liquid-phase acylation of anisole with benzoic anhydride.     

等离激元增强荧光的纳米结构、机制及其应用

基于等离激元纳米材料具有优异的光学调控性能,综述了等离激元荧光增强的基本机理,分别阐述了具有特定功能的等离激元增强荧光的纳米结构(PEFNSs)的构效关系,包括等离激元纳米核的材料、形状、尺寸、等离激元纳米颗粒(PNP)与荧光物质间的距离以及荧光物质种类对荧光增强的影响,最后综述了PEFNSs在生物传感器、生物成像和光热疗法和光动力疗法等生物医学领域中的应用,且其在生物、物理、化学等领域的应用具有重要意义。     

沉淀二氧化硅的应用与发展

本文简述了沉淀二氧化硅的制备方法、性质 ,着重介绍了它在硅橡胶、涂料及牙膏中的应用 ,并对沉淀二氧化硅的发展方向进行了概括性分析     

硅溶胶制备与应用

硅溶胶是高分子二氧化硅微粒分散于水中或有机溶剂中的胶体溶液 ,广泛应用于陶瓷、纺织、造纸、涂料、水处理、半导体等行业。介绍了硅溶胶的各种制备方法及几种特殊用途的硅溶胶的制备。阐述了影响硅溶胶稳定性的因素及其性能测试方法