We disclose the highly diastereoselective combination of monoamine oxidase‐catalyzed oxidation of meso‐pyrrolidines and aza‐Friedel–Crafts reactions in aqueous buffer to give valuable enantioenriched 2‐substituted pyrrolidines in a formal double C H activation process. A range of secondary as well as tertiary amines were shown to be suitable substrates for the biocatalytic oxidation and subsequent addition of a variety of C‐nucleophiles.
In order to determine the geographic origin of poultry and dried beef, concentrations of a total of 72 different elements
(occasionally represented with several isotopes) were analyzed by inductively coupled plasma high resolution mass spectrometry
(ICP-HRMS). Additionally, gross chemical composition (GCC) was analyzed. The 25 poultry breast filets samples originated from
Switzerland, France, Germany, Hungary, Brazil, and Thailand, and the 23 dried beef samples, made from M. biceps femoris and M. semitendinosus, were produced in Switzerland, Austria, Australia, United States, and Canada out of raw meat originating either from these
or from other countries. A total of 66 and 46 of the elements and isotopes followed were detected in beef and poultry, respectively.
For statistical analyses, only the most abundant isotopes per element were used. For both poultry meat and dried beef, a differentiation
of the origins was possible using those elements, which were significantly different across countries (As, Na, Rb, and Tl
in poultry; B, Ca, Cd, Cu, Dy, Eu, Ga, Li, Ni, Pd, Rb, Sr, Te, Tl, Tm, V, Yb, and Zn in beef). No sufficient differentiation
between origins was possible with GCC. Further studies have to confirm the suitability of this approach for meat authentication
with more samples. 相似文献
We adopted decision fusion techniques to develop a computer-aided detection (CAD) system for automatic detection of pulmonary
nodules in low-dose CT images. Two distinct phases, aimed, respectively, at detecting volumes of interests (VOIs) within the
CT scan, and at classifying VOIs into nodules and non-nodules, were considered. Three algorithms, namely thresholding, region
growing and robust fuzzy clustering, were used as VOI detectors. For the classification phase, we built multi-classifier systems,
which aggregate the decisions of three statistical classifiers, a neural network and a decision tree. Finally, the receiver
operating characteristic convex hull method was used to build the final classifier, which results to be the aggregation of
the best local behaviors of both classifiers and combiners. All the CAD modules were tested on CT scans analyzed by two expert
radiologists. In the experiments, we achieved a sensitivity of 92.5% against a specificity of 83.5%. 相似文献
The effects of both the electric and flow parameters on the lethality and energy efficiency of a pulsed electric fields (PEF) treatment were studied. An experimental plan was designed in order to study the microbial inactivation of Saccharomyces cerevisiae and Escherichia coli cells inoculated in a buffer solution. The following process parameters were taken into consideration: electric field strength (13-30 kV/cm), total specific energy input (20-110 J/mL), flow rate of the processed stream (1-4 L/h) and number of passes through the chamber (up to 5).The results showed that, at a fixed flow rate (2 L/h), microbial inactivation of both microbial strains increased with increasing field strength and applied energy input. The maximum inactivation level (5.9 Log-cycles for S. cerevisiae and 7.0 Log-cycles for E. coli) corresponded to the more intensive PEF treatment (30 kV/cm and 110 J/mL). However, for any given field strength applied, the inactivation rate decreased by increasing the energy input. This behavior was attributed to the presence of heterogeneous treatment conditions due, for example, to a different morphology (size and shape) or cell membrane (composition, structure), a local variation of the electric field strength in the treatment chamber, the tendency of microbial cells to form clusters, or a non-uniform distribution of the residence time of the product in the PEF chamber.A more effective stirring of the microbial suspensions which was achieved, at a fixed field strength (18 kV/cm), either by increasing the flow rate with a single pass operation through the PEF chamber, or by operating in re-circulating mode at a constant flow rate, provided a significant increase in the effectiveness and energy efficiency of the pulse treatment.A mathematical model based on the Weibull distribution adequately described the inactivation kinetics of both microbial strains under different flow dynamic conditions. 相似文献
Nanocomposite aerogels were prepared by chemical vapor deposition and polymerization of cyanoacrylate on the surface of bridged
polysilsesquioxane aerogels. Phenylene- and hexylene-bridged aerogels were prepared by sol–gel polymerizations and supercritical
carbon dioxide drying. Hydrophobic organic bridging groups in the polysilsesquioxane aerogels reduced the amount of adsorbed
water available for initiating polymerizations and led to higher molecular weight polycyanoacrylate than was observed with
silica aerogels. Densities increased as much as 65% due to the addition of the organic polymer, but the nanocomposite aerogels
remained highly porous with surface areas between 440 and 750 m2/g. Polycyanoacrylate–phenylene-bridged aerogel composites were the strongest with flexural strengths up to 780 kPa or 16-fold
stronger than the untreated phenylene-bridged aerogels and fivefold stronger than a silica aerogel of the same density. The
strongest polycyanoacrylate–hexylene-bridged aerogel composites had flexural strength of 285 kPa or ninefold stronger than
the untreated hexylene-bridged aerogels and twice as strong as a silica aerogel of comparable density. The greater strength
of the new composites is, in part, due to the greater strength of the bridged aerogels. However, higher molecular weight polycyanoacrylate,
due to less surface water on the hydrophobic bridged aerogels, also contributes to the greater nanocomposite strengths. 相似文献