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41.
Cinnamomum verum (Lauraceae), also known as “true cinnamon” or “Ceylon cinnamon” has been widely used in traditional folk medicine and cuisine for a long time. The systematics of C. verum presents some difficulties due to genetic variation and morphological similarity between other Cinnamomum species. The present work aimed to find chemical and molecular markers of C. verum samples from the Amazon region of Brazil. The leaf EOs and the genetic material (DNA) were extracted from samples cultivated and commercial samples. The chemical composition of the essential oils from samples of C. verum cultivated (Cve1-Cve5) and commercial (Cve6-c-Cv9-c) was grouped by multivariate statistical analysis of Principal Component Analysis (PCA). The major compounds were rich in benzenoids and phenylpropanoids, such as eugenol (0.7–91.0%), benzyl benzoate (0.28–76.51%), (E)-cinnamyl acetate (0.36–32.1%), and (E)-cinnamaldehyde (1.0–19.73%). DNA barcodes were developed for phylogenetic analysis using the chloroplastic regions of the matK and rbcL genes, and psbA-trnH intergenic spacer. The psbA-trnH sequences provided greater diversity of nucleotides, and matK confirmed the identity of C. verum. The combination of DNA barcode and volatile profile was found to be an important tool for the discrimination of C. verum varieties and to examine the authenticity of industrial sources.  相似文献   
42.
The complex study of filtration and electric properties of the samples of cement stone with different water-cement ratios is performed. It is established that filtration coefficient decreases by 4–6 times with an increase in a pressure drop and becomes constant at pressure drops above 3–3.5 MPa. The observed effect is interpreted as a reversible change in the internal structure of cement stone upon the filtration of a liquid through the stone. It is revealed that the filtration coefficient and porosity of samples decrease with time. Total open porosity and the most probable pore radius are determined by mercury porosity technique. Coefficients of structural resistance and pore tortuosity of the samples are determined from the comparison of through and total porosity. The values of streaming potential are measured and values of surface charge and potential of the samples of cement stone are calculated.  相似文献   
43.
Let B be a totally complex number field, Galois over the rational field Q, with Galois group S3, the symmetric group on three elements. The group of units of B has torsion free rank 2. In this paper, we determine the various inequivalent representations that occur of S3 acting on the group of units and determine arithmetic criteria for deciding which representation occurs for a particular field. As a result, we can give a relatively simple computational procedure for determining a pair of fundamental units of B given a fundamental unit in a cubic subfield.  相似文献   
44.
The essential oil from the aerial parts of Artemisia scoparia was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry. A total of 32 compounds were identified representing 98.0% of the total oil composition. A. scoparia oil was dominated by the diacetylenes 1-phenyl-2,4-pentadiyne (34.2%) and capillene (4.9%). Other major components were beta-pinene (21.3%), methyl eugenol (5.5%), alpha-pinene (5.4%), myrcene (5.2%), limonene (5.0%), and (E)-beta-ocimene (3.8%). The oil was tested for in-vitro cytotoxic activity against MCF-7 cells, but was inactive.  相似文献   
45.
The double addition of Grignard (alkyl, aryl, alkenyl, alkynyl) reagents to acyl cyanohydrins was performed under unusually smooth conditions with a concomitant O-N acyl transfer, providing a very simple and general access to α,α,α-trisubstituted amides.  相似文献   
46.
In recent years, convex optimization methods were successfully applied for various image processing tasks and a large number of first-order methods were designed to minimize the corresponding functionals. Interestingly, it was shown recently in Grewenig et al. (2010) that the simple idea of so-called “superstep cycles” leads to very efficient schemes for time-dependent (parabolic) image enhancement problems as well as for steady state (elliptic) image compression tasks. The “superstep cycles” approach is similar to the nonstationary (cyclic) Richardson method which has been around for over sixty years. In this paper, we investigate the incorporation of superstep cycles into the projected gradient method. We show for two problems in compressive sensing and image processing, namely the LASSO approach and the Rudin-Osher-Fatemi model that the resulting simple cyclic projected gradient algorithm can numerically compare with various state-of-the-art first-order algorithms. However, due to the nonlinear projection within the algorithm convergence proofs even under restrictive assumptions on the linear operators appear to be hard. We demonstrate the difficulties by studying the simplest case of a two-cycle algorithm in ?2 with projections onto the Euclidean ball.  相似文献   
47.
The aim of this paper is to gain more insight into vector and matrix medians and to investigate algorithms to compute them. We prove relations between vector and matrix means and medians, particularly regarding the classical structure tensor. Moreover, we examine matrix medians corresponding to different unitarily invariant matrix norms for the case of symmetric 2×2 matrices, which frequently arise in image processing. Our findings are explained and illustrated by numerical examples. To solve the corresponding minimization problems, we propose several algorithms. Existing approaches include Weiszfeld’s algorithm for the computation of ?2 vector medians and semi-definite programming, in particular, second order cone programming, which has been used for matrix median computation. In this paper, we adapt Weiszfeld’s algorithm for our setting and show that also two splitting methods, namely the alternating direction method of multipliers and the parallel proximal algorithm, can be applied for generalized vector and matrix median computations. Besides, we compare the performance of these algorithms numerically and apply them within local median filters.  相似文献   
48.
This paper reports the 6400-7400 cm−1 Fourier-transform (FT) near-infrared (NIR) emission spectrum of the BiS X22Π3/2 → X12Π1/2 fine structure bands as well as the millimeterwave rotational spectrum of the X12Π1/2 state. For the FTNIR observations, BiS was produced by reaction of bismuth with sulfur vapor and excited by energy transfer from metastable oxygen, O2(a1Δg), in a fast-flow system. As was the case for BiO [O. Shestakov, R. Breidohr, H. Demes, K.D. Setzer, E.H. Fink, J. Mol. Spectrosc. 190 (1998) 28-77], the 0.5 cm−1resolution spectrum revealed a number of strong bands in the Δv = 0 and ±1 sequences which showed perturbed band spacings, band shapes, and intensities due to avoided crossing of the X22Π3/2 and A14Π3/2 potential curves for v ? 4 of X22Π3/2. The millimeterwave rotational spectrum of BiS in its X12Π1/2 state was observed when BiS was produced in a high-temperature oven by a discharge in a mixture of Bi vapor and CS2. The signal to noise ratio was markedly improved by using a White-type multipath cell. Ninety seven features from J′ = 23.5 to J′ = 41.5 were measured between 150 and 300 GHz. Analysis of the 0.5 cm−1 resolution FT spectrum yielded the fine structure splitting and vibrational constants of the states. A simultaneous analysis of millimeterwave and a 0.005 cm−1 FT spectrum of the 0-0 band of the NIR system was carried out to give precise rotational, fine, and hyperfine constants for the X12Π1/2 and X22Π3/2 states. The results are consistent with those reported earlier for BiO and indicate only a slight decrease in the unpaired electron density in the 6p(π) orbital on the Bi atom.  相似文献   
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