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991.
Dr. Daniela Schulz Prof. Dr. Andrea Rentmeister 《Chembiochem : a European journal of chemical biology》2014,15(16):2342-2347
Over recent years, click reactions have become recognized as valuable and flexible tools to label biomacromolecules such as proteins, nucleic acids, and glycans. Some of the developed strategies can be performed not only in aqueous solution but also in the presence of cellular components, as well as on (or even in) living cells. These labeling strategies require the initial, specific modification of the target molecule with a small, reactive moiety. In the second step, a click reaction is used to covalently couple a reporter molecule to the biomolecule. Depending on the type of reporter, labeling by the click reaction can be used in many different applications, ranging from isolation to functional studies of biomacromolecules. In this minireview, we focus on labeling strategies for RNA that rely on the click reaction. We first highlight click reactions that have been used successfully to label modified RNA, and then describe different strategies to introduce the required reactive groups into target RNA. The benefits and potential limitations of the strategies are critically discussed with regard to possible future developments. 相似文献
992.
Krassimir Garbev Günter Beuchle Uwe Schweike Daniela Merz Olga Dregert Peter Stemmermann 《Journal of the American Ceramic Society》2014,97(7):2298-2307
New cementitious materials based on calcium hydrosilicate hydrates were recently developed as potential substitutes for ordinary portland cement, but with a reduced CO2 footprint. The materials are produced by hydrothermal processing of SiO2 and Ca(OH)2, giving rise to calcium silicate hydrates, followed by mechanical activation of the latter via cogrinding with various siliceous materials. Thus, the chemical composition in terms of C/S ratio could be adjusted over a broad range (1–3). In this study the synthesis of a previously unknown cementitious material produced via the combination of mechanical activation in a laboratory mill and thermal treatment of a mixture of quartz and hydrothermally synthesized calcium silicate hydrates: α‐Ca2[HSiO4](OH) (α‐C2SH) and Ca6[Si2O7](OH)6 (jaffeite) are reported. It forms independently of the type of mill used (eccentric vibrating mill, vibration grinding mill) after thermal treatment of the ground materials at 360°C–420°C. The new material is X‐ray amorphous and possesses a CaO/SiO2 ratio of 2. A characteristic feature in regards to the silicate anionic structure is the increased silicate polymerization (up to 27% Si2O7 dimers) as revealed by the trimethylsilylation method. Infrared (IR) spectra show a very broad absorption band centered at about 935 cm?1. Another characteristic feature is the presence of ~2.5 wt% H2O as shown by thermogravimetry (TG) coupled with IR spectroscopy. As this water is bound mostly as hydroxyl to Ca, we refer to this new cementitious material as calcium‐oxide–hydroxide–silicate (C–CH–S). Calorimetric measurements point to a very high hydraulic reactivity which is beyond that for typical C2S materials. The influence of the type of grinding on the thermal behavior of α‐C2SH upon its transformation into water‐free Ca2SiO4 modifications is discussed. 相似文献
993.
Dr.‐Ing. Christian Schnitzer Dr. Daniela Kruse Marina Lazar Markus Priske Dr.‐Ing. Axel Kobus 《化学,工程师,技术》2014,86(5):589-593
Organic Solvent Nanofiltration is a relatively new unit operation in fluid processing. It addresses a multitude of applications in all sectors of the chemical industry. The benefit for the customer can be a different one depending on the application, therefore, multiple process examples are discussed. Within these, organic solvent nanofiltration can be applied either as a standalone separation process or as a hybrid process in combination with other thermal separation methods. 相似文献
994.
Jana Mikešová Miroslav Šlouf Uwe Gohs Daniela Popelková Taťana Vacková Ngoc Hung Vu Jaroslav Kratochvíl Alexander Zhigunov 《Polymer Bulletin》2014,71(4):795-818
High-quality titanate nanotubes (TiNT) were mixed with modified polypropylene (PP*) by a batch melt-mixing procedure. To improve compatibility between the nanofiller and the matrix, polypropylene (PP) was modified by electron beam irradiation. Effects of TiNT nanoparticles on crystallization, mechanical, thermal and rheological properties of the modified polypropylene were studied and compared with the analogous systems filled with commercial micro- (mTiO2) and nano- (nTiO2) titanium dioxide particles. Nucleation effects of the TiO2-based fillers on PP* crystallization were investigated in detail. The microstructure of the PP*/TiNT nanocomposites shows well-dispersed TiNT sparse aggregates (clouds), penetrated by the polymer. A large-scale structure in the nanocomposite melts confirmed also rheology. In comparison to the matrix characteristics, the stiffness and microhardness of the TiNT nanocomposites increase by 27 and 33 %, respectively. The enhancement in mechanical properties demonstrates that the quality titanate nanotubes can be used as an efficient filler in non-polar polymers using the polymers modified by irradiation. In the case of the nanocomposites containing nTiO2-anatase particles, the increase in these mechanical characteristics is lower. The investigated changes in the rate of crystallization indicate a marked nucleation effect of the nanotubes. The crystallization kinetics data, processed by the Avrami equation, suggest 3-dimensional crystal growth in the polypropylene matrix. The observed improvement in mechanical properties of the TiNT nanocomposites is induced not only by the nanofiller reinforcement but also by the changes of supermolecular structure of the polymer matrix due to nucleated crystallization. 相似文献
995.
Despite the importance of entrepreneurship as an engine for socioeconomic growth, few attempts have been made to study how and to what extent industry-specific policies can sustain it. In particular, to date, there is only anecdotal evidence on which factors policy-makers can utilize to foster entrepreneurship within the agri-food sector. In this paper, we attempt to fill this gap by developing, testing, and validating a multi-item scale, identifying five factors (i.e. people, money, network, technology, infrastructure) and 16 specific tools (i.e. items) to be leveraged in promoting entrepreneurship within the agri-food industry. We carry out our study in the context of Foodbest, a pan-European public–private consortium created in 2012 to support entrepreneurship and innovation in the agri-food sector. By testing for differences in perceptions of factors’ and tools’ effectiveness, we find variations according to respondents’ organizational and country affiliation. We thus offer new insights into how public policy and public–private consortiums can proactively promote entrepreneurship in the agri-food domain.
Key Points: We cover three key points. First, by conducting a literature review and working with a focus group, we identify a set of theoretically grounded factors and tools that could help promote entrepreneurship in the agri-food industry. Second, we develop and test a multi-item scale of these factors within the context of a pan-European public–private consortium. Third, we show that perceptions of factor effectiveness vary among consortium participants according to participants’ personal characteristics and organizational affiliations. 相似文献
996.
997.
Processing of biobased feedstock materials may lead to formation of multicomponent azeotropic mixtures. Reactive separations provide an opportunity to circumvent azeotropes by changing the substance properties through chemical reactions. Exemplarily several effluents from black liquor processing contain aqueous mixtures of low molecular weight fatty acids such as formic acid and acetic acid. These mixtures form inseparable azeotropes. Separation of the system formic acid–acetic acid–water by esterification with methanol was investigated. Reactive distillation experiments in batch and continuous mode confirmed complete removal of formic acid in a first step. Acetic acid may then be isolated by distillation or by reactive distillation. 相似文献
998.
Osvaldo L. Bezzon Daniella S. H. Rivera Raquel A. B. Silva Daniela S. B. Oliveira Daniel Silva‐herzog Paulo Nelson‐filho Marília P. lucisano Léa A. B. Silva 《Microscopy research and technique》2015,78(12):1098-1103
The aim of this study was to evaluate radiographically and histologically the pulpal and periapical response to self‐adhesive (Rely X? Unicem) and self‐etching and self‐curing (Multilink®) resin‐based luting materials in deep cavities in dogs' teeth. Deep class V cavities (0.5‐mm–thick dentin) were prepared in 60 canine premolars and the following materials were applied on cavity floor: Groups I/V—RelyX? Unicem; Groups II/VI—Multilink®; Groups III/VII—zinc phosphate cement (control) and; Groups IV/VIII—gutta‐percha (control). Cavities were restored with silver amalgam. Animals were euthanized after 10 days (groups I–IV) and 90 days (groups V–VIII). Tooth/bone blocks were radiographed and processed for histopathological evaluation of pulp and periapical tissue response to the materials. All materials presented similar histopathological features and radiographic findings at both periods. The pulp tissue was intact. The apical and periapical regions and periodontal ligament thickness were normal. No inflammatory cells, resorption of mineralized tissue (dentin, cementum, and alveolar bone) or bacteria were observed. The lamina dura was intact and no areas of periapical bone rarefaction or internal/external root resorption were observed radiographically. It can be concluded that Rely X? Unicem and Multilink® caused no adverse tissue reactions and may be indicated for cementation of indirect restorations in deep dentin cavities without pulp exposure. Microsc. Res. Tech. 78:1098–1103, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
999.
Andrea Raspa Gloria A. A. Saracino Raffaele Pugliese Diego Silva Daniela Cigognini Angelo Vescovi Fabrizio Gelain 《Advanced functional materials》2014,24(40):6317-6328
Self‐assembling biomaterials offer an unprecedented chance of successfully facing most of the challenges of various biomedical fields, and, in particular, of tissue engineering. Nonetheless co‐assembling peptides (CAPs), taking advantage of the theory and empirical findings developed for self‐assembling peptides, could provide an even better control over cell cultures, drug delivery, and transplantation therapies. This study follows a “full” bottom‐up approach to develop new CAPs for neural tissue engineering applications. After molecular aggregation analysis via coarse‐grained simulations, LKLK12, LDLD12, and the functionalized KLPGWSG‐LDLD12 CAPs are synthesized and characterized assessing their co‐assembled secondary structures, the biomechanical properties of the obtained hydrogels, and the morphological features of the assembled nanofibers. The biological influence on viability and differentiation of human and murine neural stem cells are tested in vitro and neuroregenerative potentials in complete spinal cord transections are verified in vivo. Upon mixing of CAPs, the spontaneous formation of double layers of β‐sheets with a high degree of integration of the two CAP species is demonstrated. The formation of entangled nanofibrous structures give rise to shear‐thinning hydrogels. The in vitro results are comparable to a standard state‐of‐the‐art cell culture substrate and nervous regeneration in vivo is enhanced. 相似文献
1000.