The Electromagnetic Form Factor of the Kaon in the Light-Front Approach

The kaon electromagnetic form factor is calculated within a light-front constituent quark model (LFCQM). The electromagnetic components of the current are extracted from the Feynman triangle diagram within the light-front approach. We also obtain the electroweak decay constant and the charge radius for the kaon in the light-front approach. In this work, the kaon observables are calculated and a fairly good agreement is obtained with a very higher accuracy when compared with the experimental data.Comment: Paper with 4 pages, 1 figure, reference: XII HADRON PHYSICS Conference - to appear in AIP Conference Proceeding

Electromagnetic Structure of the Pion

In this work, we analyze the electromagnetic structure of the pion. We calculate its electromagnetic radius and electromagnetic form factor in low and intermediate momentum range. Such observables are determined by means of a theoretical model that takes into account the constituent quark and antiquark of the pion within the formalism of light-front field theory. In particular, we consider a nonsymmetrical vertex in this model, with which we calculate the electromagnetic form factor of the pion in an optimized way, so that we obtain a value closer to the experimental charge radius of the pion. The theoretical calculations are also compared with the most recent experimental data involving the pion electromagnetic form factor and the results show very good agreement.Comment: Paper with 4 pages, 1 figure, presented in XII HADRON PHYSICS Conference - to appear in AIP Conference Proceeding

Vortex-Antivortex annihilation dynamics in a square mesoscopic superconducting cylinder

The dynamics of the annihilation of a vortex-antivortex pair is investigated. The pair is activated magnetically during the run of a simulated hysteresis loop on a square mesoscopic superconducting cylinder with an antidot inserted at its center. We study the nucleation of vortices and antivortices by first increasing the magnetic field, applied parallel to the axis of the sample, from zero until the first vortex is created. A further increase of the field pulls the vortex in, until it reaches the antidot. As the polarity of the field is reversed, an antivortex enters the scene, travels toward the center of the sample and eventually the pair is annihilated. Depending on the sample size, its temperature, and Ginzburg-Landau parameter, the vortex-antivortex encounter takes place at the antidot or at the superconducting sea around it. The position and velocity of the vortex and antivortex singularities were evaluated as a function of time. The current density, magnetization and order parameter topology were also calculated.Comment: One REVTeX file and 5 EPS figure

Use of Cellulosic Materials as Dye Adsorbents — A Prospective Study

Cellulose is the most abundant biopolymer of nature, and it is widely used in the synthesis of new materials as well as in the adsorption of dye. This study reports a literature review (articles) and technology review (patents) about publications and product invention, which contain information on the use of cellulose on the adsorption of dyes in the period 2004–2014. For this work, research database and keywords were used to find articles and patents related to the subject under review. Specific words were used to find articles and patents related to the subject under review. After a demanding research, 1 patent and 23 articles that contain the words “cellulose,” “dye,” and “adsorption or sorption” in their titles were assessed, and annual evolution studies were performed for publications and countries that publish more

Pion and kaon elastic form factors in a refined light-front model

Within the framework of light-front field theory, we reassess the electromagnetic form factors of the pion and kaon. Comparison with experiment is made for the full range of momentum transfer, q^2<0, including recent data. The light-front model's single regulator mass, m_R, of the \bar qq bound-state vertex function is initially adjusted to reproduce the weak decay constants, f_\pi\ and f_K, and both meson's charge radii, r_\pi\ and r_K. We study the behavior of these observables under variation of the quark masses and find an optimized parameter set, m_u=m_d, m_s and m_R, for which they are in sensibly better agreement with experiment than in a previous analysis; a feature also observed for the elastic form factors, in particular at small q^2. This model refinement is important in view of an extension to vector and heavy-light mesons.Comment: 5 pages, 8 figures; minor corrections, version published in PRC C86, 038202 (2012

Chemical Functionalization of Cellulosic Materials — Main Reactions and Applications in the Contaminants Removal of Aqueous Medium

The cellulose is the most abundant biopolymer in the world and presents a higher chemical variability for presence of several hydroxyl groups. These hydroxyl groups allow surface modification of biomaterials, with insertion of several chemical groups which change cellulose characteristics. This natural biopolymer and its derivatives have been used a lot as adsorbent, from several contaminants of aqueous medium due to biocompatibility, chemical degradability, and variability. Therefore, this chapter has the objective to review the literature about several cellulose surfaces or cellulosic material (incorporation of carboxymethyl, phosphorus, carboxyl, amines, and sulfur), presenting the main characteristics of reactions and showing its adsorption in application of aqueous medium (metals, dyes, and drugs), locating the main interactions between biomaterial/contaminant

Tolerance to water deficit of cowpea genotypes

Objetivou-se, neste trabalho, avaliar o efeito do déficit hídrico sobre as características fisiológicas e produtivas do feijão-caupi e selecionar genótipos tolerantes à seca. Avaliaram-se a condutância estomática, o potencial hídrico foliar, a temperatura das folhas e a produtividade de grãos de 20 genótipos de feijão-caupi nas condições de solo e clima de Teresina, Piauí, no ano de 2008 e se conduziram dois experimentos em delineamento de blocos ao acaso com 20 tratamentos e quatro repetições, um sob déficit hídrico durante a fase reprodutiva e outro sob irrigação plena, para fins de comparação. O déficit hídrico, que foi obtido aplicando-se aproximadamente metade da lâmina requerida pelo feijão-caupi, reduziu em 72% a condutância estomática, 62% o potencial de água nas folhas, 60% a produção de grãos e aumentou em 11,7% a temperatura foliar. Nas condições de déficit hídrico treze genótipos produziram acima da média (466 kg ha-1), com destaque para o BRS-Paraguaçu, Pingo-de-ouro-1-2 e Pingo-de-ouro-2, que produziram 712 kg ha-1, 667 kg ha-1 e 642 kg ha-1, respectivamente. Em média, a produtividade de grãos dos genótipos sob irrigação plena foi 150% superior.The objective of this study was to evaluate physiological and productive characteristics of cowpea under water deficit and total irrigation, under soil and climate conditions of Teresina, Piauí State, in 2008. The stomatal conductance, leaf water potential, leaf temperature and grain yield of twenty cowpea cultivars were evaluated. Two experiments were carried out in a randomized block design with 20 treatments and four replications, one under water deficit during the reproductive phase and another one under total irrigation. The water deficit was obtained applying half of the water depth required by cowpea. The water deficit reduced 72% of the stomatal conductance, 40% the leaf transpiration, 62% of the leaf water potential, 60% of the grain yield and increased 11.7% the leaf temperature. Under water deficit, 13 genotypes produced above average (466 kg ha-1), and BRS-Paraguaçu, Pingo-de-ouro-1-2 and Pingo-de-ouro-2 presented the best grain yield with712 kg ha-1, 667 kg ha-1 and 642 kg ha-1, respectively. The average grain yield of the experiment under total irrigation was 150% higher

Biopolymeric materials used as nonviral vectors: a review

Bacterial transformation and gene transfection can be understood as being the results of introducing specific genetic material into cells, resulting in gene expression, and adding a new genetic trait to the host cell. Many studies have been carried out to investigate different types of lipids and cationic polymers as promising nonviral vectors for DNA transfer. The present study aimed to carry out a systematic review on the use of biopolymeric materials as nonviral vectors. The methodology was carried out based on searches of scientific articles and applications for patents published or deposited from 2006 to 2020 in different databases for patents (EPO, USPTO, and INPI) and articles (Scopus, Web of Science, and Scielo). The results showed that there are some deposits of patents regarding the use of chitosan as a gene carrier. The 16 analyzed articles allowed us to infer that the use of biopolymers as nonviral vectors is limited due to the low diversity of biopolymers used for these purposes. It was also observed that the use of different materials as nonviral vectors is based on chemical structure modifications of the material, mainly by the addition of cationic groups. Thus, the use of biopolymers as nonviral vectors is still limited to only a few polysaccharide types, emphasizing the need for further studies involving the use of different biopolymers in processes of gene transfer.info:eu-repo/semantics/publishedVersio

Potential wound healing effect of gel based on chicha gum, chitosan, and mauritia flexuosa oil

Wounds are considered a clinically critical issue, and effective treatment will decrease complications, prevent chronic wound formation, and allow rapid healing. The development of products based on naturally occurring materials is an efficient approach to wound healing. Natural polysaccharides can mimic the extracellular matrix and promote cell growth, thus making them attractive for wound healing. In this context, the aim of this work was to produce a gel based on chicha gum, chitosan, and Mauritia flexuosa oil (CGCHO) for wound treatment. TG and DTG analyzed the thermal behavior of the materials, and SEM investigated the surface roughness. The percentages of total phenolic compounds, flavonoids, and antioxidants were determined, presenting a value of 81.811 ± 7.257 µmol gallic acid/g Mauritia flexuosa oil, 57.915 ± 0.305 µmol quercetin/g Mauritia flexuosa oil, and 0.379 mg/mL, respectively. The anti-inflammatory was determined, presenting a value of 10.35 ± 1.46% chicha gum, 16.86 ± 1.00% Mauritia flexuosa oil, 10.17 ± 1.05% CGCHO, and 15.53 ± 0.65% chitosan, respectively. The materials were tested against Gram-negative (Klebsiella pneumoniae) and Gram-positive (Staphylococcus aureus) bacteria and a fungus (Candida albicans). The CGCHO formulation showed better antimicrobial activity against Gram-positive bacteria. In addition, an in vivo wound healing study was also performed. After 21 days of treatment, the epidermal re-epithelialization process was observed. CGCHO showed good thermal stability and roughness that can help in cell growth and promote the tissue healing process. In addition to the good results observed for the antimicrobial, antioxidant, anti-inflammatory activities and providing wound healing, they provided the necessary support for the healing process, thus representing a new approach to the wound healing process.info:eu-repo/semantics/publishedVersio