25 research outputs found
Kinetic Theory Approach to Modeling of Cellular Repair Mechanisms under Genome Stress
Under acute perturbations from outer environment, a normal cell can trigger cellular self-defense mechanism in response to genome stress. To investigate the kinetics of cellular self-repair process at single cell level further, a model of DNA damage generating and repair is proposed under acute Ion Radiation (IR) by using mathematical framework of kinetic theory of active particles (KTAP). Firstly, we focus on illustrating the profile of Cellular Repair System (CRS) instituted by two sub-populations, each of which is made up of the active particles with different discrete states. Then, we implement the mathematical framework of cellular self-repair mechanism, and illustrate the dynamic processes of Double Strand Breaks (DSBs) and Repair Protein (RP) generating, DSB-protein complexes (DSBCs) synthesizing, and toxins accumulating. Finally, we roughly analyze the capability of cellular self-repair mechanism, cellular activity of transferring DNA damage, and genome stability, especially the different fates of a certain cell before and after the time thresholds of IR perturbations that a cell can tolerate maximally under different IR perturbation circumstances
Numerical Simulations of Boundary-Forced RLW Equation with Cubic B-Spline-based Differential Quadrature Methods
A new perspective for quintic B-spline based Crank-Nicolson-differential quadrature method algorithm for numerical solutions of the nonlinear Schrödinger equation
ON THE MATHEMATICAL THEORY OF VEHICULAR TRAFFIC FLOW I: FLUID DYNAMIC AND KINETIC MODELLING
Nanofibers of gelatin and polivinyl-alcohol-chitosan for wound dressing application: fabrication and characterization
Low temperature synthesis of bioactive materials SĂntese de materiais bioativos a baixas temperaturas
Bioactive materials possess properties that allow them to interact with natural tissues to induce reactions that favor the development and regeneration of those tissues. In this study, silica was prepared by the sol-gel method, using tetraethylorthosilicate as the precursor. The calcium and phosphor sources used here were calcium ethoxy and phosphoric acid, respectively, in ethanol solvent. The solid obtained was dried at 50 ÂşC. In vitro bioactivity assays were performed by soaking the materials in simulated body fluid (SBF). The samples were characterized by transmission electron microscopy (TEM), thermal analysis and photoluminescence. TEM images of the samples before contact with SBF revealed amorphous aggregates and after 12 days in SBF showed two phases, one amorphous with large quantities of Si and O, and the other a crystalline phase whose composition contained Ca and P. The electron diffraction pattern showed a planar distance of 2.86 Ă…, corresponding to 2θ = 32.2Âş. This was ascribed to hydroxyapatite. The Eu III was used as structural probe. The relative band intensity correspondent the transition 5D0 → 7F2 / 5D0 → 7F1 showed a high symmetry surrounding the Eu III ion. These materials, produced by the sol-gel route, open up new possibilities for obtaining bioactive biomaterials for medical applications.<br>Os materiais bioativos apresentam propriedades que permitem a sua interação com um tecido de origem natural podendo induzir a sua regeneração. Neste estudo, o mĂ©todo sol-gel foi utilizado para a preparação de sĂlica dopada com Ăons cálcio e fĂłsforo, partindo dos precursores tetraetilortosilicato, etĂłxido de cálcio e ácido fosfĂłrico em etanol como solvente. O sĂłlido obtido foi seco a 50 ÂşC. Ensaios de bioatividade foram realizados in vitro em uma solução que simula o fluido corpĂłreo (SBF). As amostras foram caracterizadas por microscopia eletrĂ´nica de transmissĂŁo (MET), análise tĂ©rmica e fotoluminescĂŞncia. As imagens de MET das amostras antes do contato com SBF revelou a presença de aglomerados amorfos. Depois de 12 dias em SBF a amostra apresentou duas fases, uma amorfa com grande quantidade de silĂcio e oxigĂŞnio, e outra cristalina contendo cálcio e fĂłsforo. A difração de elĂ©trons mostrou uma distância planar de 2,86 Ă…, correspondendo a 2θ = 32,2Âş. Esse ângulo foi atribuĂdo ao principal pico da hidroxiapatita. O Ăon Eu III foi usado como sonda estrutural, apresentando em seu espectro de emissĂŁo uma intensidade relativa entre as transições 5D0 → 7F2 / 5D0 →7F1 que indica um ambiente de alta simetria para este Ăon. Estes materiais obtidos pelo mĂ©todo sol-gel a baixa temperatura apresentam possibilidade de se obter biomateriais bioativos para aplicação em medicina