New Trends on Nonlocal and Functional Boundary Value Problems

In the last decades, boundary value problems with nonlocal and functional boundary conditions have become a rapidly growing area of research. The study of this type of problems not only has a theoretical interest that includes a huge variety of differential, integrodifferential, and abstract equations, but also is motivated by the fact that these problems can be used as a model for several phenomena in engineering, physics, and life sciences that standard boundary conditions cannot describe. In this framework, fall problems with feedback controls, such as the steady states of a thermostat, where a controller at one of its ends adds or removes heat depending upon the temperature registered in another point, or phenomena with functional dependence in the equation and/or in the boundary conditions, with delays or advances, maximum or minimum arguments, such as beams where the maximum (minimum) of the deflection is attained in some interior or endpoint of the beam. Topological and functional analysis tools, for example, degree theory, fixed point theorems, or variational principles, have played a key role in the developing of this subject. This volume contains a variety of contributions within this area of research. The articles deal with second and higher order boundary value problems with nonlocal and functional conditions for ordinary, impulsive, partial, and fractional differential equations on bounded and unbounded domains. In the contributions, existence, uniqueness, and asymptotic behaviour of solutions are considered by using several methods as fixed point theorems, spectral analysis, and oscillation theory

Estudio agroeconomico del proceso de produccion de frijol (Phaseolus vulgaris) en Colombia

A methodology is presented on how to study bean production processes and its on-farm application in Colombia. The main objectives are to identify the factors limiting production and productivity, availability and use of resources, credit, technical assistance, markets, pest and weed distribution and intensity, production costs, and crop profit. The study consists of various stages: definition of the problem, antecedents, interviews with technicians and administrators, bibliographic review, definition of objectives and variables, questionnaires, pilot and final surveys, selection of areas (Antioquia, Huila, Narino, and Valle del Cauca), municipalities, and producers (177 farms with an av. of 25 ha). The av. area of bean crops is 6 ha with great differences among states; more than 60 percent of the cultivation is shared with other crops such as maize, coffee, plantain, soybeans, cassava, aracacha, peas and potatoes. Except farmers of the Valle, and to a lesser extent, those that only cultivate beans in Huila, the great majority of cultivators did not have adequate mechanical equipment for preparation, planting, harvesting, and irrigation. Seventy percentage are landowners, 10 percent tenants, and 17 percent sharecroppers. It is considered that beans need less irrigation, should be harvested quickly, and that it is the crop that produces the greatest profit; however, it is considered to be the crop representing the highest risk. Planting systems are described: on flat rows; multiple cropping on ridges; multiple cropping without rows; multiple cropping in the same flat row; multiple cropping in different rows, and mixed multiple cropping. Only 12 percent of the cultivators use improved seed and during the study, 86, 48 and 34 percent planted red, black, and both types of beans, resp. Data are presented on the intensity of land use; principle pests, diseases, and weeds are evaluated. Information on costs, storage, and marketing are also included. (CIAT

Comparative sensitivity of tumor and non-tumor cell lines as reliable approach for in vitro cytotoxicity screening of lysine-based surfactants with potential pharmaceutical applications

Surfactants are used as additives in topical pharmaceuticals and drug delivery systems. The biocompatibility of amino acid-based surfactants makes them highly suitable for use in these fields, but tests are needed to evaluate their potential toxicity. Here we addressed the sensitivity of tumor (HeLa, MCF-7) and non-tumor (3T3, 3T6, HaCaT, NCTC 2544) cell lines to the toxic effects of lysine-based surfactants by means of two in vitro endpoints (MTT and NRU). This comparative assay may serve as a reliable approach for predictive toxicity screening of chemicals prior to pharmaceutical applications. After 24-h of cell exposure to surfactants, differing toxic responses were observed. NCTC 2544 and 3T6 cell lines were the most sensitive, while both tumor cells and 3T3 fibroblasts were more resistant to the cytotoxic effects of surfactants. IC50-values revealed that cytotoxicity was detected earlier by MTT assay than by NRU assay, regardless of the compound or cell line. The overall results showed that surfactants with organic counterions were less cytotoxic than those with inorganic counterions. Our findings highlight the relevance of the correct choice and combination of cell lines and bioassays in toxicity studies for a safe and reliable screen of chemicals with potential interest in pharmaceutical industry

Optimal scheduling of smart microgrids considering electric vehicle battery swapping stations

Smart microgrids belong to a set of networks that operate independently. These networks have technologies such as electric vehicle battery swapping stations that aim to economic welfare with own resources of smart microgrids. These resources should support other services, for example, the supply of energy at peak hours. This study addresses the formulation of a decision matrix based on operating conditions of electric vehicles and examines economically viable alternatives for a battery swapping station. The decision matrix is implemented to manage the swapping, charging, and discharging of electric vehicles. Furthermore, this study integrates a smart microgrid model to assess the operational strategies of the aggregator, which can act like a prosumer by managing both electric vehicle battery swapping stations and energy storage systems. The smart microgrid model proposed includes elements used for demand response and generators with renewable energies. This model investigates the effect of the wholesale, local and electric-vehicle markets. Additionally, the model includes uncertainty issues related to the planning for the infrastructure of the electric vehicle battery swapping station, variability of electricity prices, weather conditions, and load forecasting. This article also analyzes how both the user and the providers maximize their economic benefits with the hybrid optimization algorithm called variable neighborhood search - differential evolutionary particle swarm optimization. The strategy to organize the infrastructure of these charging stations reaches a reduction of 72% in the overall cost. This reduction percentage is obtained calculating the random solution with respect to the suboptimal solution

DNA gel particles: An overview

A general understanding of interactions between DNA and oppositely charged compounds forms the basis for developing novel DNA-based materials, including gel particles. The association strength, which is altered by varying the chemical structure of the cationic cosolute, determines the spatial homogeneity of the gelation process, creating DNA reservoir devices and DNA matrix devices that can be designed to release either single- (ssDNA) or double-stranded (dsDNA). This review covers recent developments on the topic of DNA gel particles formed in water-water emulsion-type interfaces. The degree of DNA entrapment, particle morphology, swelling/dissolution behaviour and DNA release responses are discussed as a function of the nature of the cationic agent used. On the basis of designing DNA gel particles for therapeutic purposes, recent studies on the determination of the surface hydrophobicity, the haemolytic and the cytotoxic assessments of the obtained DNA gel particles have been also reported

A synthetic alternative to natural lecithins with antimicrobial properties

Two soft biocompatible cationic surfactants from the amino acid arginine, 1,2-dilauroyl-3-acetylarginyl-rac-glycerol (1212RAc) and 1,2-dimirystoyl-3-acetylarginyl-rac-glycerol (1414RAc), were prepared. Their physicochemical properties show that they can be classified as multifunctional surfactants with self-aggregation behaviour comparable to that of short-chain lecithins. The two surfactants can simultaneously stabilise water-in-oil (W/O) droplets and oil-in-water (O/W) droplets, forming multiple emulsions. They have antimicrobial activity similar to that of conventional cationic surfactants and are as harmless as amphoteric betaines. These surfactants constitute an interesting alternative to the diglycerides and lecithins in formulations that require antimicrobial properties

Nanoparticles incorporating pH-responsive surfactants as a viable approach to improve the intracellular drug delivery

The pH-responsive delivery systems have brought newadvances in the field of functional nanodevices and might allow more accurate and controllable delivery of specific cargoes, which is expected to result in promising applications in different clinical therapies. Here we describe a family of chitosan TPP (tripolyphosphate) nanoparticles (NPs) for intracellular drug delivery, which were designed using two pH-sensitive amino acid-based surfactants fromthe family Nα,Nε-dioctanoyl lysine as bioactive compounds. Lowand mediummolecularweight chitosan (LMW-CS and MMW-CS, respectively) were used for NP preparation, and it was observed that the size distribution for NPs with LMW-CS were smaller (~168 nm) than that for NPs prepared with MMW-CS (~310 nm). Hemolysis assay demonstrated the pH-dependent biomembrane disruptional capability of the constructed NPs. The nanostructures incorporating the surfactants cause negligible membrane permeabilization at pH 7.4. However, at acidic pH, prevailing in endosomes, membrane-destabilizing activity in an erythrocyte lysis assay became evident. When pH decreased to 6.6 and 5.4, hemolytic capability of chitosan NPs increased along with the raise of concentration. Furthermore, studies with cell culture showed that these pH-responsive NPs displayed low cytotoxic effects against 3T3 fibroblasts. The influence of chitosan molecular weight, chitosan to TPP weight ratio, nanoparticle size and nature of the surfactant counterion on the membrane-disruptive properties of nanoparticleswas discussed in detail. Altogether, the results achieved here showed that by inserting the lysine-based amphiphiles into chitosan NPs, pH-sensitive membranolytic and potentially endosomolytic nanocarriers were developed, which, therefore, demonstrated ideal feasibility for intracellular drug delivery

PEGylated and poloxamer-modified chitosan nanoparticles incorporating a lysine-based surfactant for pH-triggered doxorubicin release

The growing demand for efficient chemotherapy in many cancers requires novel approaches in target-delivery technologies. Nanomaterials with pH-responsive behavior appear to have potential ability to selectively release the encapsulated molecules by sensing the acidic tumor microenvironment or the low pH found in endosomes. Likewise, polyethylene glycol (PEG)- and poloxamer-modified nanocarriers have been gaining attention regarding their potential to improve the effectiveness of cancer therapy. In this context, DOX-loaded pH-responsive nanoparticles (NPs) modified with PEG or poloxamer were prepared and the effects of these modifiers were evaluated on the overall characteristics of these nanostructures. Chitosan and tripolyphosphate were selected to form NPs by the interaction of oppositely charged compounds. A pH-sensitive lysine-based amphiphile (77KS) was used as a bioactive adjuvant. The strong dependence of 77KS ionization with pH makes this compound an interesting candidate to be used for the design of pH-sensitive devices. The physicochemical characterization of all NPs has been performed, and it was shown that the presence of 77KS clearly promotes a pH-triggered DOX release. Accelerated and continuous release patterns of DOX from CS-NPs under acidic conditions were observed regardless of the presence of PEG or poloxamer. Moreover, photodegradation studies have indicated that the lyophilization of NPs improved DOX stability under UVA radiation. Finally, cytotoxicity experiments have shown the ability of DOX-loaded CS-NPs to kill HeLa tumor cells. Hence, the overall results suggest that these pH-responsive CS-NPs are highly potent delivery systems to target tumor and intracellular environments, rendering them promising DOX carrier systems for cancer therapy

Determination of Methotrexate in pH-Sensitive Chitosan Nanoparticles by Validated RP-LC and UV Spectrophotometric Methods

Nanotechnology-based drug delivery systems are in constant development and, therefore, it is of great importance to have rapid, efficient and accurate analytical methodology to quantify the encapsulated drugs. Here, simple and fast methods, by reversed-phase liquid chromatography (RP-LC) and UV spectrophotometry, were developed and validated for the determination of methotrexate (MTX) in pH-sensitive chitosan nanoparticles (CS-NPs). NPs were prepared using a modified ionotropic complexation process, in which was included a surfactant derived from Nα,Nε-dioctanoyl lysine with an inorganic sodium counterion. The RP-LC method was carried out on a Waters XBridgeTM C18 column (250 mm x 4.6 mm I.D., 5μm), with mobile phase consisted of potassium phosphate buffer (0.05 M, pH 3.2): acetonitrile (86:14, v/v), and UV detection set at 303 nm. The analyses of MTX content by the UV method were also accomplished at 303 nm, using 0.1 M sodium hydroxide as diluent. The measurements were linearly correlated with concentration for both methods in the 1 - 30 μg/mL range (r > 0.9999). The specificity tests showed that there was no interference of the NP components on the quantitative analyses. Precision (repeatability and intermediate precision) was demonstrated by a relative standard deviation lower than 1.5%, whereas the accuracy was assessed by the recovery of MTX from sample matrices, given mean value of ~99%. The proposed methods were applied for the analyses of MTX in different batches of NPs, and the results showed non-significant differences (p > 0.05) between the values obtained with both methodologies. Moreover, the RP-LC method was successfully used to determine the drug entrapment efficiency, and to quantify MTX during in vitro release assays and photolytic degradation studies. In conclusion, the validated methods are suitable to assay MTX in pH-sensitive CS-NPs without any interference from the polymer or surfactant

Termómetros Clínicos

Na prática clínica, várias decisões relacionadas com o diagnóstico e tratamento resultam da análise dos valores da temperatura corporal, sendo a medição deste parâmetro habitualmente realizada com instrumentos de medição, designados por termómetros clínicos. A correta medição da temperatura corporal assume relevância na prática diária dos cuidados de saúde, sendo um parâmetro regularmente avaliado no diagnóstico e monitorização do estado de saúde de um indivíduo.info:eu-repo/semantics/publishedVersio