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471.
High pressures up to several hundreds of MPa are utilised in a wide range of applications in chemical engineering, bioengineering, and food engineering, aiming at selective control of (bio-)chemical reactions. Non-uniformity of process conditions may threaten the safety and quality of the resulting products as the process conditions such as pressure, temperature, and treatment history are crucial for the course of (bio-)chemical reactions. Therefore, thermofluid dynamical phenomena during the high-pressure process have to be examined, and tools to predict process uniformity and to optimise the processes have to be developed. Recently, mathematical models and numerical simulations of laboratory and industrial scale high-pressure processes have been set up and validated by experimental results. This contribution deals with the assumption of the modelling that relevant (bio-)chemical compounds are ideally dissolved or diluted particles in a continuum flow. By considering the definition of the continuum hypothesis regarding the minimum particle population in a distinct volume, limitations of this modelling and simulation are addressed. 相似文献
472.
It is shown that by adding potassium nitrate (1 % by weight) to compensated cholesteric mixtures (cholesteryl chloride-cholesteryl myristate 63.63:36.37% by weight and cholesteryl laurate-cholesteryl chloride 35.65% by weight) or to smectic sitosteryl undecilenate, the mixtures exhibit ferroelectric behaviour. Values of Ps = 10-9 - 10-8 C/cm2 were obtained in the high-temperature range. In compensated cholesteric mixtures, the spontaneous polarisation reached a minimum at a temperature corresponding to the cholesteric-nematic transition. The results are explained by assuming coupling between the dipoles of the antiferroelectric KNO3 and the dipoles of the mesogenic compound. 相似文献
473.
Katrin Roemhild Cornelia Wiegand Uta‐Christina Hipler Thomas Heinze 《Macromolecular rapid communications》2013,34(22):1767-1771
Amino‐cellulose‐based nanofibers are prepared by electrospinning of blended solutions of 6‐deoxy‐6‐trisaminoethyl‐amino (TEAE) cellulose and polyvinyl alcohol (PVA). The TEAE cellulose with a degree of substitution of 0.67 is synthesized via a nucleophilic displacement reaction starting from cellulose‐p‐toluenesulfonic acid ester. Several solution characteristics such as polymer concentration, electrical conductivity, and surface tension as well as setup parameters are investigated to optimize the ability of nanofiber formation. These parameters are evaluated using the rheological studies of the solutions. The nanofibers obtained are characterized by scanning electron microscopy (SEM) and show a high antimicrobial activity against Staphylococcus aureus and Klebsiella pneumoniae.
474.
We determine the Riemannian manifolds for which the group of exact volume preserving diffeomorphisms is a totally geodesic subgroup of the group of volume preserving diffeomorphisms, considering right invariant L2-metrics. The same is done for the subgroup of Hamiltonian diffeomorphisms as a subgroup of the group of symplectic diffeomorphisms in the Kähler case. These are special cases of totally geodesic subgroups of diffeomorphisms with Lie algebras big enough to detect the vanishing of a symmetric 2-tensor field. 相似文献
475.
Kevin Bläsing Dr. Stefan Ellinger Dr. Jörg Harloff Prof. Dr. Axel Schulz Katharina Sievert Dr. Christoph Täschler Dr. Alexander Villinger Dr. Cornelia Zur Täschler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(12):4175-4188
Salts containing new cyanido(fluorido)phosphate anions of the general formula [PF6?n(CN)n]? (n=1–4) were synthesized by a very mild Lewis‐acid‐catalyzed synthetic protocol and fully characterized. All [PF6?n(CN)n]? (n=1–4) salts could be isolated on a preparative scale. It was also possible to detect the [PF(CN)5]? but not the [P(CN)6]? anion. The best results with respect to purity, yield, and low cost were obtained when the F?/CN? substitution reactions were carried out in ionic liquids. 相似文献
476.
Ana Flavia Burlec ukasz Pecio Solomiia Kozachok Cornelia Mircea Andreia Corciov Liliana Veretiuc Oana Cioanc Wiesaw Oleszek Monica Hncianu 《Molecules (Basel, Switzerland)》2021,26(5)
Tagetes erecta L. is a popular ornamental plant of the Asteraceae family, which is widely cultivated not only for its decorative use, but also for the extraction of lutein. Besides carotenoid representatives, which have been extensively studied, other important classes of secondary metabolites present in the plant, such as polyphenols, could exhibit important biological activities. The phytochemical analysis of a methanolic extract obtained from T. erecta inflorescences was achieved using liquid chromatography–mass spectrometry (LC-MS) techniques. The extract was further subjected to a multistep purification process, which allowed the separation of different fractions. The total extract and its fractions contain several polyphenolic compounds, such as hydroxybenzoic and hydroxycinnamic acid derivatives, flavonols (especially quercetagetin glycosides), and several aglycons (e.g., quercetin, patuletin). One of the fractions, containing mostly quercetagitrin, was subjected to two different antioxidant assays (metal chelating activity and lipoxygenase inhibition) and to in vitro cytotoxicity assessment. Generally, the biological assays showed promising results for the investigated fraction compared to the initial extract. Given the encouraging outcome of the in vitro assays, further purification and structural analysis of compounds from T. erecta extracts, as well as further in vivo investigations are justified. 相似文献
477.
Denisa Batir-Marin Monica Boev Oana Cioanca Cornelia Mircea Ana Flavia Burlec Galba Jean Beppe Adrian Spac Andreia Corciova Lucian Hritcu Monica Hancianu 《Molecules (Basel, Switzerland)》2021,26(9)
The sterile stems belonging to the Equisetum species are often used in traditional medicine of various nations, including Romanians. They are highly efficient in treating urinary tract infections, cardiovascular diseases, respiratory tract infections, and medical skin conditions due to their content of polyphenolic derivatives that have been isolated. In this regard, this study aimed to provide the chemical composition of the extracts obtained from the Equisetum species (E. pratense, E. sylvaticum, E. telmateia) and to investigate the biological action in vitro and in vivo. For the chemical characterization of the analyzed Equisetum species extracts, studies were performed by using ultra-high-performance liquid chromatography (UHPLC-DAD). In vitro evaluation of the antioxidant activity of the plant extracts obtained from these species of Equisetum genus was determined. The neuroprotective activity of these three ethanolic extracts from the Equisetum species using zebrafish tests was determined in vivo. All obtained results were statistically significant. The results indicate that E. sylvaticum extract has a significant antioxidant activity; whereas, E. pratense extract had anxiolytic and antidepressant effects significantly higher than the other two extracts used. All these determinations indicate promising results for the antioxidant in vitro tests and neuroprotective activity of in vivo tests, particularly mediated by their active principles. 相似文献
478.
Synthesis of Novel Cellulose Carbamates Possessing Terminal Amino Groups and Their Bioactivity 下载免费PDF全文
Kristin Ganske Cornelia Wiegand Uta‐Christina Hipler Thomas Heinze 《Macromolecular bioscience》2016,16(3):451-461
Cellulose phenyl carbonates are an excellent platform to synthesize a broad variety of soluble and functional cellulose carbamates. In this study, the synthesis of cellulose carbamates with terminal amino groups, namely ω‐aminoethylcellulose‐ and ω‐aminoethyl‐p‐aminobenzyl‐cellulose carbamate, is discussed. The products are well soluble and their structures can be clearly described by NMR spectroscopy. The cellulose carbamates exhibit a bactericide and fungicide activity in vitro. The ω‐aminoethylcellulose carbamate possesses a strong activity against Candida albicans and Staphylococcus aureus (IC50 of 0.02 mg mL?1 and 0.05 mg mL?1). The antimicrobial activity and cytotoxicity can be improved by p‐amino‐benzylamine (ABA) as an additional substituent. The mixed cellulose carbamate exhibits a high biocompatibility (LC50 of 3.18 mg mL?1) and forms films on cotton and PES, which exhibit a strong activity against S. aureus and Klebsiella pneumoniae.
479.
Doina Bejan Ecaterina Cornelia Niculescu 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(6):138
We investigated the combined effects of a non-resonant intense laser field and a static electric field on the electronic structure and the nonlinear optical properties (absorption, optical rectification) of a GaAs asymmetric double quantum dot under a strong probe field excitation. The calculations were performed within the compact density-matrix formalism under steady state conditions using the effective mass approximation. Our results show that: (i) the electronic structure and optical properties are sensitive to the dressed potential; (ii) under applied electric fields, an increase of the laser intensity induces a redshift of the optical absorption and rectification spectra; (iii) the augment of the electric field strength leads to a blueshift of the spectra; (iv) for high electric fields the optical spectra show a shoulder-like feature, related with the occurrence of an anti-crossing between the two first excited levels. 相似文献
480.
Cornelia von Baeckmann Hanspeter Kählig Mika Lindén Freddy Kleitz 《Particle & Particle Systems Characterization》2021,38(1):2000273
When a material comes in contact with serum or plasma, proteins will immediately adsorb to its surface. The extent of serum protein adsorption as well as the composition of the protein corona is thought to be decisive for the biological fate. The understanding of the mechanism underlying the concurrent adsorption of multiple proteins and the exact ways by which the adsorbed proteins interact with the biological setting, is still rudimentary. For both cases, a correct estimate of the composition of the protein corona is the key for an improved understanding. The protein corona composition is typically analyzed indirectly through analysis of the supernatant after protein desorption. However, in most cases the particles are not analyzed afterward in order to ensure that all proteins indeed have desorbed. Here, the results related to the analysis of the amounts of proteins in the corona are reported, focusing on the desorbed as well as the fraction of proteins that do not desorb. Irreversible protein adsorption can be observed in some cases. The results show that, in addition of the analysis of the supernatant, analysis of the particles is of critical importance to fully characterize the protein corona formed on nanoparticles. 相似文献