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1.
A simple spectrofluorimetric method for the determination of the fungicide benomyl in grapes is described. Benomyl is rapidly solvolysed in organic solvents to give the highly fluorescent metabolite carbendazim. Solvent effects on the spectral shape and their influence on analytical performance are studied. DMF was found to be the best solvent. The method is sensitive to 12 ng/ml benomyl, and has an RSD at the 0.5 g/ml level of 2.2%. The method is suitable for determining benomyl in spiked grapes, with recoveries in the range 97 to 104%. 相似文献
2.
The use of pesticides is a necessary practice in the modern era. Therefore, it is impossible to ignore the pesticide market, which has developed into one of the most lucrative in the world. Nowadays, humans are subjected to many potential risks, and significant amounts of toxic compounds enter their bodies through food, drink, and the air itself. Identification and quantification of these hazardous compounds is crucial for the sustainable development of an increasing world population which poses high climatic and political constraints on agricultural production systems. The maximum residue limits for pesticides have been regulated by the Codex Alimentarius Commission and European Union to protect human health. In this review, we have summarized and explained the analytical methods for pesticide extraction and determination. Also, sustainable viticulture practices like organic vineyards, tillage, biopesticides, nanobiopesticides, and precision viticulture are briefly discussed. These new techniques allow wine growers to be more profitable and efficient, while contributing to the reduction of pests and increasing the quality of wines. 相似文献
3.
二甲基黄褪色光度法测定微量碘 总被引:7,自引:0,他引:7
在硫酸介质中,溴化钾催化下,碘酸根对二甲基黄有褪色作用,且褪色的程度与碘酸根的量有关,从而建立了光度法测定碘的新方法。方法的最大吸收波长为515nm,表观摩尔吸光系数为3.1×104L·mol-1·cm-1,碘浓度在0~20μg/10ml范围内符合比耳定律,检出限为1.02×10-8g·ml-1。方法简单、快速、选择性好、灵敏度高,用于测定碘盐中碘的含量,结果满意。 相似文献
4.
This article presents the implementation and application, to two complex machines, of two holography methods called CIBNAH (Complex Intensity Based Near-field Acoustic Holography) and MRNAH (Multi Reference Near-field Acoustic Holography) based on residual spectra. The first is a newly developed method that uses complex sound intensity as its basis and hence bypasses the need for reference signals. Here, several approaches are presented to validate both methods and to investigate each method’s advantages and limitations. 相似文献
5.
Hashing is a widely used technique for data organization. Hash tables enable a fast search of the stored data and are used in a variety of applications ranging from software to network equipment and computer hardware. One of the main issues associated with hashing are collisions that cause an increase in the search time. A number of alternatives have been proposed to deal with collisions. One of them is separate chaining, in which for each hash value an independent list of the elements that have that value is stored. In this scenario, the worst case search time is given by the maximum length of that list across all hash values. This worst case is often referred to as Longest Length Probe Sequence (llps) in the literature. Approximations for the expected longest length probe sequence when the hash table is large have been proposed and an exact analytical solution has also been presented in terms of a set of recurring equations. In this paper, a novel analytical formulation of the expected longest length probe sequence is introduced. The new formulation does not require a recursive computation and can be easily implemented in a symbolic computation tool. 相似文献
6.
Glassy carbon electrode modified with phosphotungstate‐doped‐glutaraldehyde‐cross‐linked poly‐L ‐lysine (PLL‐GA‐PW) film was employed for iodate determination. The PLL‐GA‐PW film electrode shows excellent electrocatalytic activity towards iodate reduction with significant reduction of overpotential. Under optimized experimental conditions, a linear range from 5×10?8 to 2.27×10?2 M with a sensitivity of 61.75 μA mM?1 was obtained. Possible interfering species, in iodate determination, were evaluated and the applicability of proposed sensor for iodate estimation in table salt was also demonstrated. The PLL‐GA‐PW film electrode shows fast response, wider linear range, and good selectivity and stability. 相似文献
7.
Ana C. Correia 《Natural product research》2015,29(5):438-440
The aim of this study was to investigate the antioxidant capacity, radical scavenger activity, lipid oxidation protection and antimicrobial activity of grape extracts from 12 different red grape varieties cultivated in Portugal. The mean values of total phenolic content quantified in grape extracts varied from 833.7 to 2005.6 mg/L gallic acid. Antioxidant capacity results showed different values for each grape variety ranging from 3.96 to 32.96 mm/L Fe(II). The scavenger activity values ranged from 15.99% to 54.82% for the superoxide radical and from 11.79% to 29.67% for the hydroxyl radical. The grape extracts with the highest antioxidant capacity had a positive effect on the lipid oxidation protection and induced low peroxide values in butter samples. Finally, concerning antimicrobial activity, grape extracts from Touriga Nacional and Tinta Roriz grape varieties had significant antimicrobial activity, especially notable for total mesophilic aerobics. 相似文献
8.
Eric J. Beh 《Computational Statistics》2005,20(3):415-438
An exploration of the application of S-PLUS code designed to perform classical correspondence analysis is made in this paper.
This code allows for the “classical” analysis to be performed on categorical data consisting of two or more variables. For
multi-way contingency tables, correspondence analysis can be performed by considering either the indicator matrix or the Burt
matrix. The code also allows the user to incorporate into the analysis confidence circles (to identify categorical responses
that deviate from the hypothesis of independence) and for an asymmetrical analysis to be performed. The function includes
various warnings and stoppages to help the user properly analyse their data. 相似文献
9.
Zhang Guangxiang 《数学年刊B辑(英文版)》1996,17(4):411-420
§1.IntroductionZ.AradandH.Blauintroducedin[1]theconceptoftablealgebrasandusedthistodiscussthecharacteralgebraandthecentralclassalgebraofafinitegroupinauniformway.ThisideagoesbacktoI.Schur.AlittleextendednotionofC-algebraforeshadowedthedevelopmentofcommuta… 相似文献
10.
Bangteng Xu 《代数通讯》2013,41(12):5249-5263
A problem that has been open for a long time is whether an automorphism of the center of the integral group ring of a finite group permutes the class sums. As a generalization, the similar problem for integral table algebras has also been studied in a few papers. In this paper we further the investigation of the problem for integral C-algebras and table algebras. We will first present some necessary and sufficient conditions under which an algebra isomorphism between integral C-algebras is monomial, and as an application, obtain a conceptual proof of the class sum correspondence theorem of group rings of finite groups. Then we prove that an algebra isomorphism compatible with degree maps between standard integral nilpotent table algebras over the ring of algebraic integers is exact. As a direct consequence, we get Hertweck's result [6] for finite nilpotent groups. An application to association schemes is also presented. 相似文献