Chiral cis-cyclopropanes are strained rigid analogues of alkyl chains, whose study and application are limited by their difficult synthesis. A modular approach from olefin materials is enabled by the ...discovery of the electron donor–acceptor (EDA) interaction between 2-substituted benzothiazolines and N-hydroxyphthalimide esters. These complexes are activated by visible light without photocatalysts, and the benzothiazoline reagent plays a triple role as a photoreductant, a stereoselective hydrogen-atom donor, and a Brønsted acid. Beyond the enantioselective synthesis of cis-cyclopropanes, these results introduce benzothiazolines as accessible and easily tunable self-sensitized photoreductants.
The design of drug nanocarriers is a topic of current interest. To achieve a desirable efficiency, the preparation of a new nanocarrier must tune multiple complicated factors. Polyethylene glycol ...(PEG) has demonstrated the ability to evade biological barriers of living matter. In this work, the synthesis of nanocomposites prepared with PEG and carbon nanotubes (CNTs) functionalized with amine ending groups (named CNTs
amine
), which could be used as nanocarriers is described. A thorough characterization of prepared nanocomposites using Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) is presented. To explore the possibility of using the PEG/CNTs
amine
nanocomposites as suitable carriers its toxicity to HeLa cells was evaluated, their ability to release the anti-cancer drug cisplatin was determined, and their capacity to inhibit the growth of bacteria Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli as well as the fungus Candida albicans was studied. Although the PEG/CNTs
amine
nanocomposites have the ability to release the drug cisplatin with better efficacy than pure PEG, the evidence that produces a toxic effect on HeLa cells limit their practical use as suitable nanocarriers.
Ozone is a harmful tropospheric pollutant, causing the formation of reactive oxygen and nitrogen species that lead to oxidative damage in living beings. NF-κB can be activated in response to ...oxidative damage, inducing an inflammatory response. Nowadays, there are no reliable results that consolidate the use of antioxidants to protect from damage caused by ozone, particularly in highly polluted cities. Curcumin has a strong antioxidant activity and is a potent inhibitor of NF-κB activation with no side effects. The aim of this study is to evaluate the effect of curcumin in preventive and therapeutic approaches against oxidative damage, NF-κB activation, and the rise in serum levels of IL-1β and TNF-α induced by acute and chronic exposure to ozone in rat hippocampus. One hundred male Wistar rats were distributed into five groups; the intact control, curcumin-fed control, the ozone-exposed group, and the preventive and therapeutic groups. These last two groups were exposed to ozone and received food supplemented with curcumin. Lipid peroxidation was determined by spectrophotometry, and protein oxidation was evaluated by immunodetection of carbonylated proteins and densitometry analysis. Activation of NF-κB was assessed by electrophoretic mobility shift assay (EMSA), and inflammatory cytokines (IL-1β and TNF-α) were determined by ELISA. Curcumin decreased NF-κB activation and serum levels of inflammatory cytokines as well as protein and lipid oxidation, in both therapeutic and preventive approaches. Curcumin has proven to be a phytodrug against the damage caused by the environmental exposure to ozone.
Supplier selection and order quantity allocation have a strong influence on a company’s profitability and the total cost of finished products. From an optimization perspective, the processes of ...selecting the right suppliers and allocating orders are modeled through a cost function that considers different elements, such as the price of raw materials, ordering costs, and holding costs. Obtaining the optimal solution for these models represents a complex problem due to their discontinuity, non-linearity, and high multi-modality. Under such conditions, it is not possible to use classical optimization methods. On the other hand, metaheuristic schemes have been extensively employed as alternative optimization techniques to solve difficult problems. Among the metaheuristic computation algorithms, the Grey Wolf Optimization (GWO) algorithm corresponds to a relatively new technique based on the hunting behavior of wolves. Even though GWO allows obtaining satisfying results, its limited exploration reduces its performance significantly when it faces high multi-modal and discontinuous cost functions. In this paper, a modified version of the GWO scheme is introduced to solve the complex optimization problems of supplier selection and order quantity allocation. The improved GWO method called iGWO includes weighted factors and a displacement vector to promote the exploration of the search strategy, avoiding the use of unfeasible solutions. In order to evaluate its performance, the proposed algorithm has been tested on a number of instances of a difficult problem found in the literature. The results show that the proposed algorithm not only obtains the optimal cost solutions, but also maintains a better search strategy, finding feasible solutions in all instances.
The Stern–Gerlach experiment (SGE) is one of the foundational experiments in quantum physics. It has been used in both the teaching and the development of quantum mechanics. However, for various ...reasons, some of its quantum features and implications are not fully addressed or comprehended in the current literature. Hence, the main aim of this paper is to demonstrate that the SGE possesses a quantum nonlocal character that has not previously been visualized or presented before. Accordingly, to show the nonlocality into the SGE, we calculate the quantum correlations C ( z , θ ) by redefining the Banaszek–Wódkiewicz correlation in terms of the Wigner operator, that is C ( z , θ ) = ⟨ Ψ | W ^ ( z , p z ) σ ^ ( θ ) | Ψ ⟩ , where W ^ ( z , p z ) is the Wigner operator, σ ^ ( θ ) is the Pauli spin operator in an arbitrary direction θ and | Ψ ⟩ is the quantum state given by an entangled state of the external degree of freedom and the eigenstates of the spin. We show that this correlation function for the SGE violates the Clauser–Horne–Shimony–Holt Bell inequality. Thus, this feature of the SGE might be interesting for both the teaching of quantum mechanics and to investigate the phenomenon of quantum nonlocality.
A Distribution Centre (DC) is considered a critical node in providing optimal customer service levels in a supply chain network. Therefore, improving order fulfilment time at DCs becomes critical to ...achieve world-class operations. One of the key processes involved in order fulfilment is that of picking, the activity that consumes most time when fulfilling an order. This article presents the analysis of an actual system that stores products in a random fashion and releases orders following FIFO rules. A simulation model is built, and two scenarios analysed. The first one (baseline) reflects the current DC operation. The second scenario (projected) includes the implementation of three picking strategies aimed at improving system performance: slotting, wave picking, and expedite picking (balancing picker's workload). The following KPIs are used to compare both scenarios: order fulfilment lead-time, picks per man-hour, average picking time per order, average time to pack an order. Simulation results show that the systematic implementation of the proposed strategies achieves substantial improvements, not only in the order fulfilment time (54% reduction), but also in the number of orders completed in less than 8 hours, the number of orders picked per man hour and a reduction of pickers idle time.
El artículo describe algunos encargos y prácticas cosméticas corporales a las cuales se ve sometida la niñez, considerando que el mercado se dirige incisivamente al infante como consumidor ...preeminente y decisorio. Mediante una investigación documental y etnográfica en Ciudad Juárez, Chihuahua, México, se analizó información recuperada por documentos impresos y gráficos, observaciones, entrevistas y un grupo focal. El infante funge como cliente inédito dentro del mercado de la belleza que le oferta una plétora de productos, servicios personalizados y escenarios para su exhibición. Así, el cuerpo infantil se encuentra investido en un conjunto de signos que lo determinan incipientemente al mercado corporal, donde predominan justipreciaciones y miradas adultas, cuestionando los límites etarios y generacionales en las maneras de los niños.
Functionalized furoquinoline derivatives are easily obtained in a one‐pot three‐component coupling process that involves the reaction of 4‐pentyn‐1‐ol derivatives and N‐arylaldimines in the presence ...of catalytic amounts of a platinum(II) complex (see scheme).
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