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1.
Uranium concentration varies from 9.01 to 12.7, 8.03 to 11.5, 9.1 to 14.0 and 10.1 to 14.2 mg/kg in grab sediment, coarse sand fraction, fine sand fraction, silt and clay fraction respectively. Thorium concentration varies from 20.0 to 29.4, 17.3 to 28.6, 19.6 to 30.4 and 21.1 to 35.9 in grab sediment, coarse sand fraction, fine sand fraction, silt and clay fraction respectively. Uranium and thorium concentrations vary in different size fractionated sediment samples like silt and clay fraction > fine sand fraction > coarse sand fraction.  相似文献   

2.
Inter simple sequence repeat markers were employed for the genotyping of 16 plantain ecotypes. Two different electrophoretic systems namely conventional gel electrophoresis (CVGE) and fully automated high‐resolution CGE were used to evaluate the genetic diversity. Comparative analysis indicated that all parameters related to marker informativeness were higher in CGE except polymorphic information content. But genetic diversity parameters like effective number of alleles, Nei's gene diversity (1973) and Shannon's information index showed higher values (1.52 ± 0.12, 0.34 ± 0.05 and 0.52 ± 0.05, respectively) in CVGE as against CGE (1.29 ± 0.04, 0.22 ± 0.02 and 0.38 ± 0.03, respectively) system. The unweighed pair group method with arithmetic averages was used to obtain the dendrogram for both analyses. The results of dendrogram and principal component analysis were found to be consistent in both systems except for some minor disagreements. The clone‐specific bands could be used in the identification and development of SCAR markers. Inter simple sequence repeat markers used in this study provided sufficient polymorphism and reproducible banding pattern for evaluating the genetic diversity of different plantain ecotypes. Lack of accuracy and consistency of the CVGE warrants the employment of high‐throughput CGE for diversity analysis as it provided better separation of bands with higher resolution.  相似文献   

3.
Haematococcus pluvialis is the largest producer of natural astaxanthin in the world. Astaxanthin is a bioactive compound used in food, feed, nutraceutics, and cosmetics. In this study, astaxanthin extraction from H. pluvialis by supercritical fluid extraction was evaluated. The effects of temperature (40 and 50 °C), pressure (40 and 50 MPa), and CO2 flow rate (2 and 4 L/min) were investigated. The results showed that the highest astaxanthin recovery was obtained at 50 °C/50 MPa and the CO2 flow rates evaluated had no significant effect. It was possible to achieve astaxanthin recoveries of 95% after 175 min for a CO2 flow rate of 2 L/min, and 95 min for CO2 flow rate of 4 L/min. The ω-6/ω-3 ratios obtained were similar in all conditions, reaching 0.87, demonstrating that the extracts from H. pluvialis by SFE are rich in unsaturated fatty acids (UFA) which increases their positive effects when used as a functional ingredient in food.  相似文献   

4.
Vitex rotundifolia is a widely distributed plant species that has been extensively used in traditional Chinese medicine. Its fruits, Fructus Viticis, are recorded as Manjingzi in the Pharmacopoeia of the People's Republic of China. For the effective quality control of its medicinal values reflected by chemical variation patterns, in addition to the relationship with genetic diversity, analyses based on high-performance liquid chromatographic (HPLC) fingerprinting and inter simple sequence repeat (ISSR) molecular markers were carried out, involving 14 V. rotundifolia populations from different locations in China. The HPLC data showed considerable variation of chemical constituents among the V. rotundifolia populations. The hierarchical clustering analysis further revealed four major groups based on their chemotype variation. Abundant genetic diversity was detected among the V. rotundifolia populations that also were clustered into four groups based on their ISSR data. It is important to point out that the genetic variation pattern revealed by molecular markers was closely associated with that indicated by chemical constitutes in the fruits of V. rotundifolia. This finding provides a solid basis for the combined use of chemical and genetic fingerprints in efficiently evaluating qualities and choosing favourable chemotypes with appropriate pharmacological properties of V. rotundifolia, in addition to establishing good agricultural practices for medicinal plants.  相似文献   

5.
Akhil Mahajan  Anju Arya 《合成通讯》2019,49(15):1926-1937
Nanoparticles have been used century ago but have regained their importance in recent years being simple, ecofriendly, pollutant free, nontoxic, low-cost approach, and due good atom economy. In this report, we have demonstrated the synthesis of silver nanoparticles using green algae (Chlorella vulgaris) which in turn was used for synthesis of biologically important quinolines. Algal extract was prepared and treated with silver nitrate solution for the synthesis of silver nanoparticles. Synthesized nanoparticles were characterized with the help of analytical tools like UV, FTIR, X-ray, and SEM and used as a catalyst for the synthesis of quinolines.  相似文献   

6.
Density functional theory (DFT) calculations have been carried out for a series of Cu(I) complexes bearing N-hexadentate macrocyclic dinucleating ligands and for their corresponding peroxo species (1c-8c) generated by their interaction with molecular O2. For complexes 1c-7c, it has been found that the side-on peroxodicopper(II) is the favored structure with regard to the bis(mu-oxo)dicopper(III). For those complexes, the singlet state has also been shown to be more stable than the triplet state. In the case of 8c, the most favored structure is the trans-1,2-peroxodicopper(II) because of the para substitution and the steric encumbrance produced by the methylation of the N atoms. Cu(II) complexes 4e, 5e, and 8e have been obtained by O2 oxidation of their corresponding Cu(I) complexes and structurally and magnetically characterized. X-ray single-crystal structures for those complexes have been solved, and they show three completely different types of Cu(II)2 structures: (a) For 4e, the Cu(II) centers are bridged by a phenolate group and an external hydroxide ligand. The phenolate group is generated from the evolution of 4c via intramolecular arene hydroxylation. (b) For 5e, the two Cu(II) centers are bridged by two hydroxide ligands. (c) For the 8e case, the Cu(II) centers are ligated to terminally bound hydroxide ligands, rare because of its tendency to bridge. The evolution of complexes 1c-8c toward their oxidized species has also been rationalized by DFT calculations based mainly on their structure and electrophilicity. The structural diversity of the oxidized species is also responsible for a variety of magnetic behavior: (a) strong antiferromagnetic (AF) coupling with J = -482.0 cm(-1) (g = 2.30; rho = 0.032; R = 5.6 x 10(-3)) for 4e; (b) AF coupling with J = -286.3 cm(-1) (g = 2.07; rho = 0.064; R = 2.6 x 10(-3)) for 5e; (c) an uncoupled Cu(II)2 complex for 8e.  相似文献   

7.
8.
This paper studies MgCl2/internal donor/TiCl4//external donor/AlEt3 catalytic systems where ethyl benzoate (E.B.) or 2,2,6,6 tetramethylpiperidine (TMPiP) are used as internal and external donors. E.B. as external donor does not change the molecular weight of the product with TMPiP as internal donor. The molecular weight of polypropylene decreases drastically and global productivity and stereoselectivity are very low with MgCl2/internal Donor/TiCl4//external donor/AlEt3 when TMPiP is the external and internal donor. In this case the insoluble fraction in n-heptane is highly stereospecific and the molecular weight is similar to commercial products. We present a new explanation of these results, based on Ystenes proposal, comparing both precatalysts.  相似文献   

9.
Silver nanoparticles (Ag NPs) were successfully synthesized using AgNO3 via an eco-friendly and simple green route using Abelmoschus esculentus (L.) pulp extract at room temperature. The phytochemicals present in A. esculentus (L.) pulp extract were used both as a reducing and a stabilizing agent for the synthesis of Ag NPs. The stabilization of Ag NPs with phytochemicals was justified using Fourier-transform infrared spectroscopy. The size of the as-synthesized Ag NPs was examined using dynamic light scattering and confirmed by transmission electron microscopy. The crystalline nature of Ag NPs had been identified using X-ray diffraction. The present study demonstrated the efficacy of Ag NPs against Jurkat cells in vitro. Our study also showed that the IC50 dose of Ag NPs leads to the increase in intracellular reactive oxygen species and significantly diminished mitochondrial membrane potential, indicating the effective involvement of apoptosis in cell death. The synthesized Ag NPs also exhibited good antimicrobial activity against different gram class bacteria.  相似文献   

10.
The density functional theory (DFT)-based Becke's three parameter hybrid exchange functional and Lee-Yang-Parr correlation functional (B3LYP) calculations and Born-Oppenheimer molecular dynamics (BOMD) simulations have been performed to understand the stability of different anions inside fullerenes of various sizes. As expected, the stability of anion inside the fullerene depends on its size as well as on the size of the fullerene. Results show that the encapsulation of anions in larger fullerenes (smaller fullerene) is energetically favorable (not favorable). The minimum size of the fullerene required to encapsulate F(-) is equal to C(32). It is found from the results that C(60) can accommodate F(-), Cl(-), Br(-), OH(-), and CN(-). The electron density topology analysis using atoms in molecule (AIM) approach vividly delineates the interaction between fullerene and anion. Although F(-)@C(30) is energetically not favorable, the BOMD results reveal that the anion fluctuates around the center of the cage. The anion does not exhibit any tendency to escape from the cage.  相似文献   

11.
Profiling of the main metabolites from several licorice (Glycyrrhiza glabra) samples collected at different locations is carried out in this work by using comprehensive two-dimensional liquid chromatography (LC × LC) coupled to diode array (DAD) and mass spectrometry (MS) detectors. The optimized method was based on the application of a HILIC-based separation in the first dimension combined with fast RP-based second dimension separation. This set-up was shown to possess powerful separation capabilities allowing separating as much as 89 different metabolites in a single sample. Identification and grouping of metabolites according to their chemical class were achieved using the DAD, MS and MS/MS data. Triterpene saponins were the most abundant metabolites followed by glycosylated flavanones and chalcones, whereas glycyrrhizic acid, as expected, was confirmed as the main component in all the studied samples. LC × LC-DAD-MS/MS was able to resolve these complex licorice samples providing with specific metabolite profiles to the different licorice samples depending on their geographical origin. Namely, from 19 to 50 specific compounds were exclusively determined in the 2D-chromatograms from the different licorice samples depending on their geographical origin, which can be used as a typical pattern that could potentially be related to their geographical location and authentication.  相似文献   

12.
A combined approach of subwindow factor analysis and orthogonal projection resolution was used to analyze the volatile components of cut tobacco samples from different sources. After extracted with simultaneous distillation and extraction method, the volatile components in cut tobacco from five different locations were detected by GC-MS. Then, the qualitative and quantitative analysis of the volatile components of cut tobacco from Changde area was completed with the help of subwindow factor analysis resolving two-dimensional original data into pure mass spectra and chromatograms. One hundred and two volatile components among 138 separated peaks were identified and quantified, accounting for about 88.90% of the total content. Finally, orthogonal projection method was used to extract the common peaks from different locations. Among the identified components, there were 74 components coexisting in five studied samples although the relative content of each component showed difference to some extent. The results showed a fair consistency in their GC-MS fingerprints. It was the first time to apply orthogonal projection method to compare different cut tobacco samples, and it reduced the burden of qualitative analysis as well as the subjectivity. The obtained results proved the combined approach powerful for the analysis of complex cut tobacco samples. The developed method can be used to compare the sameness and differences of cut tobacco from different sources and for quality control of cigarette production and materials.  相似文献   

13.
Cross-linked hyperbranched fluoropolymer (HBFP) and poly(ethylene glycol) (PEG) amphiphilic networks with PEG weight percentages of 14% (HBFP-PEG14), 29% (HBFP-PEG29), 45% (HBFP-PEG45), and 55% (HBFP-PEG55) were prepared on 3-aminopropyl)triethoxysilane (3-APS) functionalized microscope glass slides for marine antifouling and fouling-release applications. The surface-free energies (gamma(s)), polar (gamma(s)(p) and gamma(s)(AB)), and dispersion (gamma(s)(d) and gamma(s)(LW)) components were evaluated using advancing contact angles by two-liquid geometric-mean and three-liquid Lifshitz-van der Waals acid-base approaches. The HBFP coating exhibited a low surface energy of 22 mJ/m(2), while the gamma(s) and gamma(s)(p) of the cross-linked HBFP-PEG coatings increased proportionally with the PEG weight percentages in the networks. The adsorption of bovine serum albumin (BSA), lectin from Codium fragile (CFL), lipopolysaccharides from Escherichia coli (LPSE) and Salmonella minnesota (LPSS) upon glass, APS-glass, HBFP, PEG, and the cross-linked HBFP-PEG network coatings were investigated by fluorescence microscopy. The marine antifouling and fouling-release properties of the cross-linked HBFP-PEG coatings were evaluated by settlement and release assays involving zoospores of green fouling alga Ulva (syn. Enteromorpha; Hayden, H. S.; Blomster, J.; Maggs, C. A.; Silva, P. C.; Stanhope, M. J.; Waaland, J. R. Eur. J. Phycol. 2003, 38, 277). The growth and release of Ulva sporelings were also investigated upon the HBFP-PEG45 coating in comparison to a poly(dimethylsiloxane) elastomer (PDMSE) standard material. Of the heterogeneous cross-linked network coatings, the maximum resistances to protein, lipopolysaccharide, and Ulva zoospore adhesion, as well as the best zoospore and sporeling release properties, were recorded for the HBFP-PEG45 coating. This material also exhibited better performance than did a standard PDMSE coating, suggesting its unique applicability in fouling-resistance applications.  相似文献   

14.
The blending of a precursor polymer for poly(p‐phenylene benzobisthiazole) (PBZT) with various matrix polymers was attempted, followed by heat conversion of the PBZT precursor polymer to obtain molecular composites consisting of PBZT and the matrix polymers. A higher concentration of mixed solution using organic solvent and milder conditions to remove the solvent could be applied to blend the polymers using the precursor polymer in place of rodlike PBZT. The dispersibility of PBZT in the matrix polymer in the blended materials obtained depended on the ability to form intermolecular hydrogen bridges between the PBZT precursor and the matrix polymer. In particular, the blended material, obtained using a nonthermoplastic aromatic polyamide as the matrix polymer having a molecular structure similar to that of the PBZT prepolymer, was transparent and showed excellent reinforcing efficiency of PBZT. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 189–197, 1999  相似文献   

15.
Supercritical fluid extraction (SFE) provides an environmentally green technique to decontaminate chromium species from solid matrices using supercritical fluid carbon dioxide (ScCO2). Methanol and a small amount of water were found to significantly improve the extraction efficiency. The fluorinated chelating agent lithium bis(trifluoroethyl)-dithiocarbamate (LiFDDC) was effective in removing Cr ions in methanol-modified CO2 via in situ chelation/SFE technique. This paper indicates that the extraction efficiencies of Cr(III) and Cr(VI) from solid matrices can be greatly increased to more than 92% in the presence of a small amount of water, using 5% methanol-modified CO2 containing LiFDDC as an extractant. Chromium species in a wood waste sample in the form of chromated copper arsenate (CCA) can be extracted, but the extraction efficiency is not as good as expected, possibly due to the complications of the chemistry of Cr species in different oxidation states and to matrix effects.  相似文献   

16.
Black pepper (Piper nigrum; BP), known as the ‘king of spices’, imported from various countries is widely available in Saudi Arabian markets, as its demand as a food as well as a medicine for minor ailments is increasing in the country. However, there is a lack of appropriate information regarding these samples in terms of quality variation and standardization. We thus aimed to evaluate the quality and standardize the BP sample with respect to its physicochemical characters, active principle variation [i.e. piperine (PPN)], toxicity, and biological activity. The main focus is to validate whether any difference exists in the quality and quantity of active principle in these samples. For this purpose, physicochemical (chemical tests and ash values) and instrumental analyses [accelerated solvent extraction (ASE), ultra-high-pressure liquid chromatography (UHPLC)-diode array detector, infrared (IR), nuclear magnetic resonance (NMR), and inductively coupled plasma-MS (ICP-MS)] and biological evaluation {in vitro antioxidant activity [2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] and cytotoxicity assay} were performed. An extract yield (g) with %recovery of 2.26 ± 4.24 (11.3) was obtained for the Vietnamese sample, using a fast and rapid method of extraction (ASE). These values were 1.22 ± 2.64 (6.1) and 0.75 ± 1.69 (3.75) for the Pakistani and Indian samples. Physicochemical tests revealed the presence of flavonoids and phenolic compounds in all samples; however, in the Vietnamese sample a low amount of total, acid-insoluble, and high water-soluble ash value was noted. IR and NMR was applied to further standardize the samples. Results of ICP-MS analysis showed a high amount of macronutrients and micronutrients in the samples tested while UHPLC analysis revealed a high amount of PPN (ng/mL) in the Pakistani sample (1,362,614.09); these values were 1,051,848.04 and 768,512.81 for the Vietnamese and Indian samples, respectively. In vitro antioxidant and cytotoxicity activities revealed higher potential for the Vietnamese sample. The samples were properly standardized and effectively differentiated in terms of quality and biological activities using a fast and reliable method, however it certainly does not mean that a particular geographical region is more better or productive in terms of herbal products.  相似文献   

17.
Fructus Xanthii (Cang-Er-Zi) is a traditional Chinese medicine that is used in curing nasal diseases and headache according to the Chinese Pharmacopoeia. For the effective quality control of its medicinal values, reflected by chemical variation patterns, in addition to the relationship with genetic diversity, analyses based on UV spectrophotometry, HPLC fingerprinting and inter-simple sequence repeat (ISSR) molecular markers were carried out, involving 16 Xanthium populations from different locations in China. The HPLC data showed considerable variation of chemical constituents among the 16 Xanthium populations, and they were classified to three chemotypes by hierarchical clustering analysis. Abundant genetic diversity was detected among the Xanthium populations, which were also clustered into three groups based on their ISSR data and varied according to different species. Combining the genetic divergence and chemical differences showed an important result that, in the two chemotypes, the higher contents of total phenolic acids (TPA) in Fructus Xanthii showed greater genetic diversity (I). We suggest that genetic diversity affects the contents of TPA. Since variable phenolic acid contents may affect therapeutic efficacy, it is important to point out that combining the use of genetic base with chemotype will help control the favourable chemotypes and breed new cultivars with more desirable chemical constituents.  相似文献   

18.
脂肪醛和脂肪酮的沸点与分子结构关系的拓扑化学研究   总被引:7,自引:0,他引:7  
王克强 《有机化学》1998,18(5):419-424
根据分子拓扑学原理,通过采用信息量丰富的染色分子图代替隐氢图,借助于距离矩阵表征分子图中顶点的连接性和标识分子图中顶点性质的差异,发展了一种适用于含杂原子分子体系结构性能研究的新方法,据此探讨了脂肪醛和脂肪酮的沸点与分子结构之间的关系,提出一个既能合理表征结构性能关系、又能预测沸点的定量关系式。结果表明,沸点预测值与实验值的一致性令人满意,平均误差0.21%。  相似文献   

19.
Different structures have been found for poly(α-tetrathiophene) [poly(α-4TF)] electrosynthesized on Pt by anodic oxidation of 1.0 mM monomer solutions in media such as 45:35:20 (v/v/v) acetonitrile/THF/DMF, 45:35:20 (v/v/v) acetonitrile/ethanol/DMF and 72:28 (v/v) acetonitrile/DMF containing 0.1 M LiClO4; as well as 72:28 (v/v) acetonitrile/DMF with 0.1 M NaClO3, under dynamic and static conditions at 25 °C. In all cases the polymer was generated by chronoamperometry at 1.000 V vs. Ag∣AgCl, corresponding to the first oxidation peak detected by cyclic voltammetry. Uniform, adherent, insoluble and black polymer films were obtained under these conditions. The resulting structures have been elucidated by combining the information of their IR spectrum, nox-value and doping level of the counterion. The degree of crosslinking of every polymer has been quantified and related to the molecular flow of monomer on the Pt electrode. A monomer concentration flow between 4 × 10−6 and 5 × 10−6 mmol cm−2 s−1 was determined as the limiting value below which the polymer grows with crosslinking. This value corresponds to the electropolymerization rate of α-4TF by Pt area unit at 25 °C.  相似文献   

20.
Research on Chemical Intermediates - The 1-phenyl-2-(α-pyridyl)ethanol [or 1-phenyl-2-(2-pyridyl)ethanol] compound was obtained from the Knoevenagel condensation reaction between...  相似文献   

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