The objective of this study is to describe the experience of displaced women in Medellín, Colombia, and how this circumstance has an impact on the roles and perceptions of health/illness. This was a ...qualitative study using symbolic interactionism. Instruments from the Grounded Theory methodology were used. The study population was composed of adult women who have been displaced for at least 1 year and who live in 3 settlements in the city of Medellín. The instruments for data collection were 15 semi-structured interviews, 6 focus groups, and 6 in-depth interviews. Coding, categorization and interpretation, and, lastly, theorizing were used for analysis. What women go through displacement affects the roles they play both in relation to their family - one of the most significant components of their lives -, and in the social/community and health/illness processes, turning them into people with high degrees of vulnerability and social marginalization. Women who have been displaced face multiple obstacles, losses, and transformations, leading to a decline in their physical and mental health.
The synthesis of strained carbocyclic building blocks is relevant for Medicinal Chemistry, and methylenecyclobutanes are particularly challenging with current synthetic technology. Careful inspection ...of the reactivity of 1.1.1propellane and diboron reagents has revealed that bis(catecholato)diboron (B2cat2) can produce a bis(borylated) methylenecyclobutane in a few minutes at room temperature. This reaction constitutes the first example of B–B bond activation by a special apolar hydrocarbon and also the first time that propellane is electrophilically activated by boron. Mechanistic studies including in situ NMR kinetics and DFT calculations demonstrate that the diboron moiety can be directly activated through coordination with the inverted sigma bond of propellane, and reveal that DMF is involved in the stabilization of diboronate ylide intermediates rather than the activation of the B–B bond. These results enable new possibilities for both diboron and propellane chemistry, and for further developments in the synthesis of methylenecyclobutanes based on propellane strain release.
The synthesis of strained carbocyclic building blocks is relevant for Medicinal Chemistry, and methylenecyclobutanes are particularly challenging with current synthetic technology. Careful inspection ...of the reactivity of 1.1.1propellane and diboron reagents has revealed that bis(catecholato)diboron (B2cat2) can produce a bis(borylated) methylenecyclobutane in a few minutes at room temperature. This reaction constitutes the first example of B-B bond activation by a special apolar hydrocarbon and also the first time that propellane is electrophilically activated by boron. Mechanistic studies including in situ NMR kinetics and DFT calculations demonstrate that the diboron moiety can be directly activated through coordination with the inverted sigma bond of propellane, and reveal that DMF is involved in the stabilization of diboronate ylide intermediates rather than the activation of the B-B bond. These results enable new possibilities for both diboron and propellane chemistry, and for further developments in the synthesis of methylenecyclobutanes based on propellane strain release.The synthesis of strained carbocyclic building blocks is relevant for Medicinal Chemistry, and methylenecyclobutanes are particularly challenging with current synthetic technology. Careful inspection of the reactivity of 1.1.1propellane and diboron reagents has revealed that bis(catecholato)diboron (B2cat2) can produce a bis(borylated) methylenecyclobutane in a few minutes at room temperature. This reaction constitutes the first example of B-B bond activation by a special apolar hydrocarbon and also the first time that propellane is electrophilically activated by boron. Mechanistic studies including in situ NMR kinetics and DFT calculations demonstrate that the diboron moiety can be directly activated through coordination with the inverted sigma bond of propellane, and reveal that DMF is involved in the stabilization of diboronate ylide intermediates rather than the activation of the B-B bond. These results enable new possibilities for both diboron and propellane chemistry, and for further developments in the synthesis of methylenecyclobutanes based on propellane strain release.
Two-Phase Synthesis of (−)-Taxuyunnanine D Wilde, Nathan C; Isomura, Minetaka; Mendoza, Abraham ...
Journal of the American Chemical Society,
04/2014, Letnik:
136, Številka:
13
Journal Article
Recenzirano
Odprti dostop
The first successful effort to replicate the beginning of the Taxol oxidase phase in the laboratory is reported, culminating in the total synthesis of taxuyunnanine D, itself a natural product. ...Through a combination of computational modeling, reagent screening, and oxidation sequence analysis, the first three of eight C–H oxidations (at the allylic sites corresponding to C-5, C-10, and C-13) required to reach Taxol from taxadiene were accomplished. This work lays a foundation for an eventual total synthesis of Taxol capable of delivering not only the natural product but also analogs inaccessible via bioengineering.
(Borylmethyl)trimethylsilanes are important building blocks in organic synthesis displaying a unique reactivity. Yet, the synthesis of more advanced derivatives is limited by the advanced silicon ...intermediates required for their preparation. Herein, a one-pot synthesis of (borylmethyl)silanes is developed, sourced on available alkyl-, aryl-, alkoxy-, aryloxy-, and silyl-hydrosilane materials. The privileged reactivity of N-hydroxyphthalimidyl diazoacetate (NHPI-DA) in Si–H insertion and α-silyl redox-active esters in different decarboxylative borylation reactions are scrutinized.
The aim of this paper is to solve a multi-period supplier selection and inventory lot-sizing problem with multiple products in a serial supply chain. Compared to previous models proposed in the ...literature, our research incorporates a richer cost structure involving joint replenishment costs for raw material replenishment and production, and a more realistic description of the transportation costs represented as a vector of full-truck load costs for different size trucks. This problem can be displayed graphically as a time-expanded transshipment network defined by nodes and arcs that can be reached by feasible material flows. First, we propose an
integrated
mixed integer linear programming model that minimizes the cost over the entire supply chain for a given planning horizon. The model determines the optimal dynamic supplier selection, inventory lot-sizing, and production schedule simultaneously. Second, a
sequential
approach is proposed to solve the same problem. That is, a production schedule is determined first, and then a supplier selection and replenishment strategy is obtained according to that predetermined schedule. Sensitivity analysis comparing the two approaches is performed. Results show that, even though the integrated approach achieves the minimum cost, the sequential approach may be suitable for solving large-scale instances of the problem as it requires less information sharing and generates a near-optimal solution with shorter implementation time and computational effort.
Supply chain disruptions compel professionals all over the world to consider alternate strategies for addressing these issues and remaining profitable in the future. In this study, we considered a ...four-stage global supply chain and designed the network with the objectives of maximizing profit and minimizing disruption risk. We quantified and modeled disruption risk as a function of the geographic diversification of facilities called supply density (evaluated based on the interstage distance between nodes) to mitigate the risk caused by disruptions. Furthermore, we developed a bi-criteria mixed-integer linear programming model for designing the supply chain in order to maximize profit and supply density. We propose an interactive fuzzy optimization algorithm that generates efficient frontiers by systematically taking decision-maker inputs and solves the bi-criteria model problem in the context of a realistic example. We also conducted disruption analysis using a discrete set of disruption scenarios to determine the advantages of the network design from the bi-criteria model over the traditional profit maximization model. Our study demonstrates that the network design from the bi-criteria model has a 2% higher expected profit and a 2.2% lower profit variance under disruption than the traditional profit maximization solution. We envisage that this model will help firms evaluate the trade-offs between mitigation benefits and mitigation costs.
•Two Closed Loop Supply Chain configurations are modeled as Integer Linear Programs.•An integer relaxation allows less computational complexity.•Configurations are designed for different types of ...products in practice.•Analysis on case studies and hypothetical datasets show encouraging results.
Growing concern about environmental deterioration, manifested in new laws to protect the environment and business competition, has stimulated the idea of Closed Loop Supply Chains (CLSC). This paper develops strategic decision-making models for two different CLSCs with multiple products over multiple periods. One of the networks has six levels, while the other has four levels, and they can be applied to products with different levels of complexity during inspection and remanufacturing operations. The supply chain networks are modeled as Integer Linear Programs (ILP) designed to assist decision-making in terms of location/allocation, transportation, and inventory. Taking advantage of the properties of the formulations, we propose an integer relaxation approach to obtain the optimal solution to ILP. The proposed models and methodologies are illustrated with case studies from the literature and with hypothetical datasets. This research contributes with design standard configurations for CLSCs that can be used for different types of products. Directly using these configurations is advantageous because the models proposed can be quickly solved using the integer relaxation approach. The associated trials confirm the utility of the models for the case studies and demonstrate encouraging results for the hypothetical datasets.
Photoexcited dihydronicotinamides like NADH and analogues have been found to generate alkyl radicals upon reductive decarboxylation of redox-active esters without auxiliary photocatalysts. This ...principle allowed aliphatic photocoupling between redox-active carboxylate derivatives and electron-poor olefins, displaying surprising water and air-tolerance and unusually high coupling rates in dilute conditions. The orthogonality of the reaction in the presence of other carboxylic acids and its utility in the functionalization of DNA is presented, notably using visible light in combination with NADH, the ubiquitous reductant of life.
PDF
