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51.
A survey about the current status and potential of the predictive Soave-Redlich-Kwong (PSRK) group contribution equation of state (EoS) is given. The PSRK method combines the SRK EoS with the UNIFAC group contribution model by the PSRK mixing rule. The availability of a large number of interaction parameters between UNIFAC and new PSRK main groups allows calculating the phase equilibrium behavior and other thermodynamic quantities for various kinds of systems even with strong electrolytes. Different fields of application are discussed: the prediction of gas solubilities in asymmetric systems, the air solubility calculated for mixed solvents, the removal of H2S from natural gas by predicting the physical absorption, and the calculation of the enthalpy effects of absorption processes with pressure and temperature. 相似文献
52.
AbstractShewhart control charts are known to be somewhat insensitive to shifts of small and moderate size. Expectedly, alternative control schemes such as the exponentially weighted moving average (EWMA) charts have been proposed to speed up the detection of such shifts. Unfortunately, applying the ordinary EWMA recursion to count data leads to a control statistic no longer with a fixed discrete range. Therefore, we propose a novel chart which relies on a EWMA control statistic where the usual scalar product is replaced by a thinning operation. Actually, we use the new fractional binomial thinning to avoid the typical over-smoothing ascribable to ceiling, rounding, and flooring operations. The properties of this discrete statistic are similar to the ones of its continuous EWMA counterpart and the run length (RL) performance of the associated chart can be computed exactly using the Markov chain approach for independent and identically distributed (i.i.d.) counts. Moreover, this chart is set in such way that: the average run length (ARL) curve attains a maximum in the in-control situation, i.e., the chart is ARL-unbiased; and the in-control ARL is equal to a pre-specified value. We use the R statistical software to provide compelling illustrations of this unconventional EWMA chart and to compare its RL performance with the ones of a few competing control charts for the mean of i.i.d. Poisson counts. 相似文献
53.
Eugene A Smirnov Maria A Meledina Alexey V Garshev Vitaly I Chelpanov Sven Frost Jan U Wieneke Mathias Ulbricht 《Polymer International》2013,62(5):836-841
Titania microspheres with narrow size distribution and diameters of about 1 µm were prepared and subsequently functionalized using surface‐initiated atom transfer radical polymerization (ATRP) of N‐isopropylacrylamide. The ATRP initiator was immobilized on the particle surface via acylation of surface hydroxyl groups with α‐bromoisobutyryl bromide. Subsequently, an established ATRP reaction system was used for the preparation of titania surface‐grafted poly(N‐isopropylacrylamide) (PNiPAAm). Characterization was performed with electron microscopies, X‐ray diffraction, infrared spectroscopy and dynamic light scattering. It was found that the particle size in aqueous dispersions changed reversibly with temperature as expected for a shell of PNiPAAm, a polymer with a lower critical solution temperature at 32 °C. This confirmed the successful preparation of functional, stimuli‐responsive TiO2 microparticles via a straightforward controlled surface‐initiated polymerization method. 相似文献
54.
The importance of strain-free (total) resonant sextet benzenoid hydrocarbons is pointed out. The first computer-aided generation and enumeration of such systems is reported, and the data represent substantial supplements to the previous numbers of strain-free resonant sextet benzenoid isomers. Supplementary depictions of some forms of the systems in question are also provided. Constant-isomer series are delineated for the resonant sextet benzenoids. The numbers associated with these series are found to match exactly the known numbers for corresponding constant-isomer series of strictly pericondensed benzenoids. 相似文献
55.
56.
Due to process stability and excellent effluent quality, the use of membrane processes is rapidly expanding. However, a drawback is the production of concentrates and their proper disposal. In this study, reverse osmosis concentrate was treated by Fenton and O3/UV oxidation processes. The concentrate contains halogenated compounds, recalcitrant COD and low biodegradability. The removal of halogenated compounds and the enhancement of biodegradability were examined. Comparing the investigated processes, Fenton oxidation resulted in a better mineralization of organic matter; however, O3/UV oxidation achieved a better enhancement of the biodegradability. Furthermore, similar degradation of halogenated compounds were observed for both oxidation processes. 相似文献
57.
Ivan Gutman Sven J. Cyvin Vesna Petrović Aleksandar Teodorović 《Polycyclic Aromatic Compounds》2013,33(3):183-189
Abstract A fully-naphthalenoid hydrocarbon (FUN) is a benzenoid hydrocarbon whose all π-electrons can be (formally) grouped into disjoint naphthalene-units. The cyclic conjugation in FUNs is studied by means of the energy-effects of their various cycles. It is found that the dominant conjugation modes in FUNs are those involving the 6- and 10-membered cycles of the “full” naphthalene fragments. The cycles belonging to the “empty” domains of a FUN have significantly smaller energy-effects. 相似文献
58.
Influence of shear flow on the preparation of polymer layered silicate nanocomposites 总被引:1,自引:0,他引:1
In this paper the influence of melt-processing on the final polymer/layered silicate nanocomposite morphology is discussed. In particular the role of shear forces on the transformation of the original large clay agglomerates is of interest. Several polymer nanocomposites were prepared by melt-extrusion, involving polycaprolactone, poly(ethylene oxide), polyamide-12 or polyamide-6 as the matrix polymer. The nanocomposite morphology was characterised by X-ray diffraction and transmission electron microscopy and the clay tactoid morphology with polarised optical microscopy and scanning electron microscopy. The development of the tactoid and nanocomposite morphology during melt-mixing under shear was studied time-resolved by optical microscopy in conjunction with a rheometer and synchrotron X-ray scattering together with a Couette type flow cell. The shear forces in the melt-preparation of polymer layered mineral nanocomposites facilitate the break-up of large-sized agglomerates, whereas the extent of further exfoliation of the mineral layers is determined by the compatibility between the polymer matrix and the mineral layers rather than by shear forces. 相似文献
59.
Karin Nuernberg Gerd Nuernberg Klaus Ender Dirk Dannenberger Wiebke Schabbel Sven Grumbach Wolfgang Zupp Hans Steinhart 《European Journal of Lipid Science and Technology》2005,107(10):737-745
The aim of this study was to produce high‐quality meat from lambs under different feeding conditions, as measured by the accumulation of n‐3 fatty acids and conjugated linoleic acids (CLA) in muscle and subcutaneous fat. In total, 13 male crossbred lambs (Black Head×Gotland), each at 24 kg live weight, were divided into two feeding groups. Lambs were kept either on pasture (pasture grazing, n = 6) or in the stable (concentrate feeding, n = 7). The linolenic acid (C18:3n‐3) contained in the grass was absorbed and deposited into the different lipid classes of muscle and subcutaneous fat. The proportion of total n‐3 fatty acids in the different lipids of grazing lambs was significantly (p = 0.05) higher compared to that in concentrate‐fed lambs. The n‐6/n‐3 ratio (mean ± SEM) in muscle of grazing lambs was 1.2 ± 0.09 in contrast to 2.3 ± 0.09 (p = 0.05) of the animals kept in the stable. In subcutaneous fat, this ratio was 0.9 ± 0.2 in lambs kept on pasture versus 3.5 ± 0.2 (p = 0.05) after indoor keeping. The relative concentration of C18:1trans‐11 in total muscle lipids, phospholipids, triacylglycerols and subcutaneous fat was significantly increased by grass feeding compared to concentrate feeding. Significant influences of feeding were shown for saturated fatty acids. In concentrate‐fed lambs, a lower content of saturated fatty acids was detected. The proportion of CLAcis‐9,trans‐11 (1.9 ± 0.2% vs. 1.1 ± 0.1% in muscle, 2.5 ± 0.2% vs. 1.4 ± 0.2% in subcutaneous fat, 0.7 ± 0.04% vs. 0.4 ± 0.04% in phospholipids) in lambs was significantly (p = 0.05) higher after grazing than after concentrate feeding, respectively. 相似文献
60.
Dr. Robert Kuhnert Dr. Lydia Kuhnert Dr. Menyhárt-B. Sárosi Sven George Dr. Dijana Draca Dr. Svetlana Paskas Dr. Bettina Hofmann Prof. Dr. Dieter Steinhilber Prof. Dr. Walther Honscha Prof. Dr. Sanja Mijatović Prof. Dr. Danijela Maksimović-Ivanić Prof. Dr. Evamarie Hey-Hawkins 《ChemMedChem》2022,17(1):e202100588
12-Lipoxygenase is crucial for tumour angiogenesis. 5,6,7-Trihydroxy-2-phenyl-4H-1-benzopyran-4-one (baicalein) is a suitable inhibitor for this enzyme but is rapidly metabolised in vivo. Thus, an improvement of the metabolic stability is necessary to enhance the therapeutic efficiency. An emerging approach to enhance metabolic stability of carbon-based pharmaceuticals is the use of metabolically stable, non-toxic boron clusters, such as dicarba-closo-dodecaborane(12)s (carboranes) as phenyl mimetics. Therefore, the unsubstituted phenyl ring of baicalein was replaced by meta-carborane, resulting in borcalein, the carborane analogue of baicalein. This substitution resulted in a decreased inhibitory activity toward 12-lipoxygenase, but led to increased toxicity in melanoma (A375, B16, B16F10) and colon cancer cell lines (SW480, HCT116, CT26CL25) with decreased tumour selectivity in comparison to baicalein. Surprisingly, borcalein displays a different mechanism of cytotoxicity with increased intracellular production of reactive oxygen species (ROS), reactive nitrogen species (RNS) and nitric oxide (NO). 相似文献