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1.
《Arabian Journal of Chemistry》2021,14(11):103421
Processing of Carapa guianensis seeds to obtain oil on an industrial scale generates a significant amount of by-product, approximately 66% w/w, which is called cake and is a potential source of biomolecules, including simple phenolic structures. For this reason, studies were carried out on the chemical profiles of hydrolyzed extract from this agro-industrial by-product through High Performance Thin-Layer Chromatography (HPTLC) and Gas Chromatography coupled to Mass Spectrometry (GC–MS). These techniques were used to detect metabolic classes and/or groups, and to identify, for the first time, thirteen simple phenolic acids in this by-product. The sample antioxidant capacity was determined by methods of 2,2-diphenyl-1-picrylhydrazyl (DPPH)and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS+) radicals direct sequestration. The hydrolyzed fraction showed a total of 63.47% in the relative abundance of the total of compounds, standing out: p-hydroxybenzoic acid (39.19%) and protocatechuic acid (3,4-dihydroxybenzoic acid) (5.62%), both from hydroxybenzoic acids and 3-(3,4-dihydroxyphenyl)lactic acid, (7.76%) hydroxycinnamic acids derivatives. In these results, the fraction rich in simple phenolic acids was obtained, attributing the prominent behavior of this matrix antioxidant activity, expressed by (IC50: of 16.42 µg/mL and 6.52 µg/mL for DPPH and ABTS+ radicals, respectively). The research demonstrated an alternative to applicability that involves sustainability from agro-industrial. These techniques were used to detect metabolic classes and/or groups, and to identify, for the first time, thirteen simple phenolic acids in this by-product, generating a process capable of converting biomass into a bioproduct, consisting of bioactive compounds, in addition to adding value to the industrial chain. 相似文献
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Efficient measurement of the performance index (the distance of a loading parameter from the voltage collapse point) is one of the key problems in power system operations and planning and such an index indicates the severity of a power system with regard to voltage collapse. There exist many interesting methods and ideas to compute this index. However, some successful methods are not yet mathematically justified while other mathematically sound methods are often proposed directly based on the bifurcation theory and they require the initial stationary state to be too close to the unknown turning point to make the underlying methods practical.This paper first gives a survey of several popular methods for estimating the fold bifurcation point including the continuation methods, bifurcation methods and the test function methods (Seydel's direct solution methods, the tangent vector methods and the reduced Jacobian method) and discuss their relative advantages and problems. Test functions are usually based on scaling of the determinant of the Jacobian matrix and it is generally not clear how to determine the behaviour of such functions. As the underlying nonlinear equations are of a particular type, this allows us to do a new analysis of the determinants of the Jacobian and its submatrices in this paper. Following the analysis, we demonstrate how to construct a class of test functions with a predictable analytical behaviour so that a suitable index can be produced. Finally, examples of two test functions from this class are proposed. For several standard IEEE test systems, promising numerical results have been achieved. 相似文献
4.
高效液相色谱切换波长法测定油菜内源激素 总被引:1,自引:0,他引:1
采用反相高效液相色谱法(HPLC)切换波长法同时测定油菜中的内源激素赤霉素(GA3)、3-吲哚乙酸(IAA)和脱落酸(ABA),以甲醇:水:乙腈(20:60:20)为流动相,结果显示其检出限分别为GA3:0.08mg/L;IAA:0.015mg/L;ABA:0.025mg/L,比单波长检测的检出限提高了4-10倍;相对标准偏差(RSD)分别为GA3:6.3%,IAA:4.34%,ABA:7.95%.本实验采用切换波长法,显著减低了各组分的检出限,建立了一种以高灵敏度对多组分体系同时进行检测的方法.同时为快速、准确测定油菜内源激素提供了可靠方法. 相似文献
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This paper examines the performance of Commodity Trading Advisors (CTAs) using fixed and variable benchmarking models. In
order to avoid the troublesome passive and active commodity and managed futures benchmarks (indices) when examining the performance
of CTAs, we innovate by using data envelopment analysis (DEA). Because this alternative class has non-linear returns due to
long/short positions, and derivatives (i.e., dynamic trading strategies), DEA can alleviate the problems usually associated
with these indices. The effectiveness of using benchmarking models in a DEA setting will provide investors with an alternative
technique in assessing the performance and identifying efficient CTAs. 相似文献
7.
The peeling of a d-dimensional set of points is usually performed with successive calls to a convex hull algorithm; the optimal worst-case convex hull algorithm, known to have an O(n˙ Log (n)) execution time, may give an O(n˙n˙ Log (n)) to peel all the set; an O(n˙n) convex hull algorithm, m being the number of extremal points, is shown to peel every set with an O(n-n) time, and proved to be optimal; an implementation of this algorithm is given for planar sets and spatial sets, but the latter give only an approximate O(n˙n) performance. 相似文献
8.
具有两台专用机,两台通用机的Q4//Cmax问题的近似算法 总被引:8,自引:1,他引:7
本文讨论具有两台专用机、两台通用机的两组工件的同种类平行机的Q4//Cmax问题,对这类特殊的排序问题,提出一种启发式算法,得到了最差情况下性能指标的严格的界. 相似文献
9.
We evaluate the financial performance of most of the branch offices of a large European savings bank for a recent accounting
period. We employ a complementary pair of nonparametric techniques to evaluate their financial performance, in terms of their
ability to conserve on the expenses they incur in building their customer bases and providing customer services. We find variation
in the ability of branch offices to perform this task, and agreement on the identity of the laggard branches. We then employ
parametric techniques to determine that the list of indicators on which their financial performance is evaluated can be reduced
without statistically significant loss of information to bank management. Both findings suggest ways in which the bank can
increase the profitability of its branch network.
A previous version of this paper was presented at CORE, Université Catholique de Louvain, Louvain-la-Neuve, Belgium, where
we received many helpful comments from the audience. We are grateful to three referees for their helpful comments as well. 相似文献
10.
将反相高效液相色谱法用于原油脱钙工艺排水体系中缓蚀剂浓度测定研究,建立了缓蚀剂的快速分离检测方法.使用C18柱,以乙腈∶二氯甲烷=9∶1(V/V)混合溶剂为流动相,采用紫外检测器在300 nm处对排水体系中的缓蚀剂进行测定,外标法进行定性定量分析.测定结果表明缓蚀剂浓度在100~900 mg/kg时其峰面积与相应的质量浓度有良好的线性关系,其线性相关系数为0.999 9,相对标准偏差(RSD)和相对误差(RD%)都小于2.0%.用二氯甲烷为萃取剂对排水体系中的缓蚀剂进行萃取,其平均回收率为100%±2%.最低检测线为0.75mg/kg.该方法具有测定结果准确可靠,操作简便快速,重现性好等特点. 相似文献