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231.
The risk response development phase is a major phase in the project risk management process. We present a model that integrates project work contents, risk events, and risk reduction actions and their effects into a comprehensive framework. The model allows the representation of the overlapping effects of multiple risk reduction actions and of the impacts of secondary risk events, and supports the evaluation of the total risk exposure of the project under various combinations of risk reduction actions. The model can be treated with optimisation techniques in order to generate the most cost-effective combination of risk reduction actions. In this work we describe the model, outline a solution procedure and illustrate its application with an example taken from the software industry. 相似文献
232.
Sheldon Yoshio Okada Raz Jelinek Deborah Charych 《Angewandte Chemie (International ed. in English)》1999,38(5):655-659
A blue to red color change is induced on addition of phospholipase A2 to modified PDA vesicles 1 (PDA=polydiacetylene). This bathochromic transition results from chemical modification of the vesicles by hydrolysis of the enzyme substrate embedded in the PDA matrix. Addition of a known phospholipase inhibitor or removal of Ca2+ ions suppresses the color change, which suggests the potential for applications in high‐throughput screening assays. 相似文献
233.
Dr. Ashley J. Winter Dr. R. Nisha Khanizeman Dr. Abigail M. C. Barker-Mountford Dr. Andrew J. Devine Dr. Luoyi Wang Dr. Zhongshu Song Dr. Jonathan A. Davies Prof. Paul R. Race Dr. Christopher Williams Prof. Thomas J. Simpson Prof. Christine L. Willis Prof. Matthew P. Crump 《Angewandte Chemie (International ed. in English)》2023,62(47):e202312514
Mupirocin is a clinically important antibiotic produced by a trans-AT Type I polyketide synthase (PKS) in Pseudomonas fluorescens. The major bioactive metabolite, pseudomonic acid A (PA−A), is assembled on a tetrasubstituted tetrahydropyran (THP) core incorporating a 6-hydroxy group proposed to be introduced by α-hydroxylation of the thioester of the acyl carrier protein (ACP) bound polyketide chain. Herein, we describe an in vitro approach combining purified enzyme components, chemical synthesis, isotopic labelling, mass spectrometry and NMR in conjunction with in vivo studies leading to the first characterisation of the α-hydroxylation bimodule of the mupirocin biosynthetic pathway. These studies reveal the precise timing of hydroxylation by MupA, substrate specificity and the ACP dependency of the enzyme components that comprise this α-hydroxylation bimodule. Furthermore, using purified enzyme, it is shown that the MmpA KS0 shows relaxed substrate specificity, suggesting precise spatiotemporal control of in trans MupA recruitment in the context of the PKS. Finally, the detection of multiple intermodular MupA/ACP interactions suggests these bimodules may integrate MupA into their assembly. 相似文献
234.
Madison L. Williams Aghogho Abigail Olomukoro Ronald V. Emmons Nipunika H. Godage Emanuela Gionfriddo 《Journal of separation science》2023,46(23):2300571
Matrix effects can significantly impede the accuracy, sensitivity, and reliability of separation techniques presenting a formidable challenge to the analytical process. It is crucial to address matrix effects to achieve accurate and precise measurements in complex matrices. The multifaceted nature of matrix effects which can be influenced by factors such as target analyte, sample preparation protocol, composition, and choice of instrument necessitates a pragmatic approach when analyzing complex matrices. This review aims to highlight common challenges associated with matrix effects throughout the entire analytical process with emphasis on gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry, and sample preparation techniques. These techniques are susceptible to matrix effects that could lead to ion suppression/enhancement or impact the analyte signal at various stages of the analytical workflow. The assessment, quantification, and mitigation of matrix effects are necessary in developing any analytical method. Strategies can be implemented to reduce or eliminate the matrix effect by changing the type of ionization, improving extraction and clean-up methods, optimization of chromatography conditions, and corrective calibration methods. While development of an effective strategy to completely mitigate matrix effects remains elusive, an integrated approach that combines sample preparation, analytical extraction, and effective instrumental analysis remains the most promising avenue for identifying and resolving matrix effects. 相似文献
235.
Grace W. Muna Emily Barrera Lucas Robinson Hiba Majeed Keon Jones Abigail Damschroder Andrew Vila 《Electroanalysis》2023,35(8):e202300019
This work reports on the electroanalytical performance of a glassy carbon electrode (GCE) modified with antimony and bismuth (Sb/Bi-GCE) in detecting heavy metal ions using lead and cadmium as model analytes. The electroanalytical performance of the Sb/Bi-GCE surface was compared to the bismuth modified glassy carbon electrode (Bi-GCE) as well as the antimony modified glassy carbon electrode (Sb-GCE). The Sb/Bi-GCE exhibited excellent figures of merit compared to Bi-GCE and Sb-GCE surfaces. For example, the limit of detection for lead was 0.01 ppb using Sb/Bi-GCE and 0.1 and 1 ppb on Bi-GCE and Sb-GCE, respectively. 相似文献
236.
James F. Ponder Jr. Shawn A. Gregory Amalie Atassi Abigail A. Advincula Joshua M. Rinehart Guillaume Freychet Gregory M. Su Shannon K. Yee John R. Reynolds 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202211600
Herein, a route to produce highly electrically conductive doped hydroxymethyl functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) films, termed PEDOT(OH) with metal-like charge transport properties using a fully solution processable precursor polymer is reported. This is achieved via an ester-functionalized PEDOT derivative [PEDOT(EHE)] that is soluble in a range of solvents with excellent film-forming ability. PEDOT(EHE) demonstrates moderate electrical conductivities of 20–60 S cm−1 and hopping-like (i.e., thermally activated) transport when doped with ferric tosylate (FeTos3). Upon basic hydrolysis of PEDOT(EHE) films, the electrically insulative side chains are cleaved and washed from the polymer film, leaving a densified film of PEDOT(OH). These films, when optimally doped, reach electrical conductivities of ≈1200 S cm−1 and demonstrate metal-like (i.e., thermally deactivated and band-like) transport properties and high stability at comparable doping levels. 相似文献