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Britto, Sylvia,Leskes, Michal,Hua, Xiao,Hé,bert, Claire-Alice,Shin, Hyeon Suk,Clarke, Simon,Borkiewicz, Olaf,Chapman, Karena W.,Seshadri, Ram,Cho, Jaephil,Grey, Clare P. American Chemical Society 2015 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.137 No.26
<P>Vanadium sulfide VS<SUB>4</SUB> in the patronite mineral structure is a linear chain compound comprising vanadium atoms coordinated by disulfide anions [S<SUB>2</SUB>]<SUP>2–</SUP>. <SUP>51</SUP>V NMR shows that the material, despite having V formally in the d<SUP>1</SUP> configuration, is diamagnetic, suggesting potential dimerization through metal–metal bonding associated with a Peierls distortion of the linear chains. This is supported by density functional calculations, and is also consistent with the observed alternation in V–V distances of 2.8 and 3.2 Å along the chains. Partial lithiation results in reduction of the disulfide ions to sulfide S<SUP>2–</SUP>, via an internal redox process whereby an electron from V<SUP>4+</SUP> is transferred to [S<SUB>2</SUB>]<SUP>2–</SUP> resulting in oxidation of V<SUP>4+</SUP> to V<SUP>5+</SUP> and reduction of the [S<SUB>2</SUB>]<SUP>2–</SUP> to S<SUP>2–</SUP> to form Li<SUB>3</SUB>VS<SUB>4</SUB> containing tetrahedral [VS<SUB>4</SUB>]<SUP>3–</SUP> anions. On further lithiation this is followed by reduction of the V<SUP>5+</SUP> in Li<SUB>3</SUB>VS<SUB>4</SUB> to form Li<SUB>3+x</SUB>VS<SUB>4</SUB> (<I>x</I> = 0.5–1), a mixed valent V<SUP>4+</SUP>/V<SUP>5+</SUP> compound. Eventually reduction to Li<SUB>2</SUB>S plus elemental V occurs. Despite the complex redox processes involving both the cation and the anion occurring in this material, the system is found to be partially reversible between 0 and 3 V. The unusual redox processes in this system are elucidated using a suite of short-range characterization tools including <SUP>51</SUP>V nuclear magnetic resonance spectroscopy (NMR), S K-edge X-ray absorption near edge spectroscopy (XANES), and pair distribution function (PDF) analysis of X-ray data.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2015/jacsat.2015.137.issue-26/jacs.5b03395/production/images/medium/ja-2015-03395v_0013.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja5b03395'>ACS Electronic Supporting Info</A></P>
Protective Effects of Grape Juice on Vascular Damage Induced by Chlorine Free Radical in Rats
Jose Britto Junior,Diego Antonio Costa Arantes,Karla Carnerio Siqueira Leite,Eric de Souza Gil,Matheus Lavorenti Rocha 한국식품영양과학회 2021 Preventive Nutrition and Food Science Vol.26 No.4
Grapes and their derivatives have antioxidant and cardioprotective properties. Therefore, we hypothesized that grape juice (GJ) could improve vascular oxidative damage caused by chlorine radicals (OCl<SUP>−</SUP>), which are excessively produced in vascular tissue during cardiovascular diseases (mainly diabetes and hypertension). The antioxidant capacity of GJ was analyzed by an electrochemical method, followed by administration in rats (100 or 300 mg/kg/d, via the oral) for seven days. Then, rats were sacrificed, and their aortas were isolated and subjected to isometric recordings or immunohistochemical analyses with or without exposure to OCl<SUP>−</SUP> (5, 20, or 100 μM, 60 min). Concentration-effect curves for acetylcholine (ACh) and sodium nitroprusside (SNP) were derived to analyze endothelium-dependent or independent vasorelaxation. The GJ presented with high antioxidant capacity, and treatment with GJ did not alter vascular relaxation induced by ACh or SNP. After exposure to OCl<SUP>−</SUP>, endothelium-denuded arteries showed preserved relaxation with SNP, whereas endothelium-intact arteries showed reduced relaxation with ACh. OCl<SUP>−</SUP> at various concentrations induced significantly decreased relaxation of arteries (80.6±4.2%, 55.4±4.7%, and 28.1±5.9%, respectively) vs. control arteries (96.8±2.4%). However, treatment with GJ prevented loss in relaxation caused by 5 and 20 μM OCl<SUP>−</SUP> and improved relaxation after exposure to 100 μM OCl<SUP>−</SUP>. Exposure to OCl<SUP>−</SUP> induced increased nitrotyrosine immunostaining of endothelial cell layers, which was improved by GJ treatment. Altogether, vascular damage caused by OCl<SUP>−</SUP> was prevented by treatment with GJ, and GJ prevented nitrosative stress in these vessels.
Green Synthesis and Radial Breathing Modes in Ti Nanoparticles
R. Britto-Hurtado,M. CORTEZ-VALADEZ,Ramón A. B. Alvarez,P. Horta-Fraijo,J.-G. BOCARANDO-CHACON,R. Gamez-Corrales,A. Perez-Rodríguez,F. Martínez-Suarez,F. Rodríguez-Melgarejo,H. Arizpe-Chavez,M. FLORES 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.5
This work presents the synthesis of metallic nanoparticles of titanium. The extract from the nopal (Opuntia ficus-indica) plant was used as the redactor agent. The results of transmission electronic microscopy (TEM) show that nanoparticles have a sphere-like shape with an approximate diameter of 1 – 4 nm. The presence of Ti in these particles was corroborated by energy dispersive X-ray spectroscopy (EDS). Optical properties were detected with the presence of absorption bands centered in 295 nm and 355 nm, similar to those reported in the literature. Two Raman bands centered at 359 cm-1 and 404 cm-1 were observed after the synthesis of titanium nanoparticles. Afterwards, structural and vibrational parameters of small clusters of Ti (Tin, n=3 – 13) were analyzed by the density functional theory (DFT) at the B3LYP level of approximation combined with the basis set LANL2DZ. Radial breathing modes (RBMs) were detected in the vibrational spectrum of each cluster, placed around 298 – 387 cm-1.
John Britto X.,Muthuraj M.P. 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.70 No.6
This paper examines the applicability of artificial neural network (ANN) and multivariate adaptive regression splines (MARS) to predict the compressive strength of bacteria incorporated geopolymer concrete (GPC). The mix is composed of new bacterial strain, manufactured sand, ground granulated blast furnace slag, silica fume, metakaolin and fly ash. The concentration of sodium hydroxide (NaOH) is maintained at 8 Molar, sodium silicate (Na2SiO3) to NaOH weight ratio is 2.33 and the alkaline liquid to binder ratio of 0.35 and ambient curing temperature (28°C) is maintained for all the mixtures. In ANN, back-propagation training technique was employed for updating the weights of each layer based on the error in the network output. Levenberg-Marquardt algorithm was used for feed-forward back-propagation. MARS model was developed by establishing a relationship between a set of predictors and dependent variables. MARS is based on a divide and conquers strategy partitioning the training data sets into separate regions; each gets its own regression line. Six models based on ANN and MARS were developed to predict the compressive strength of bacteria incorporated GPC for 1, 3, 7, 28, 56 and 90 days. About 70% of the total 84 data sets obtained from experiments were used for development of the models and remaining 30% data was utilized for testing. From the study, it is observed that the predicted values from the models are found to be in good agreement with the corresponding experimental values and the developed models are robust and reliable.
G.Britto Antony Xavier,S.Gokulakrishnan,V.Chandrasekar 장전수학회 2014 Advanced Studies in Contemporary Mathematics Vol.24 No.3
In this paper, we derive the numerical-comlete solution of the generalized higher order difference equation and obtain the value of sum of partial sums of product of polynomials and polynomials factorials in the field of finite difference methods. Suitable examples are provided to illustrate the main results.
( Pradima J Britto ),( Rajeswari M Kulkarni ),( Archna Narula ),( Sunaina Poonacha ),( Rakshita Honnatagi ),( Sneha Shivanathan ),( Waasif Wahab ) 한국화학공학회 2022 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.60 No.1
Biodiesel production has attracted attention as a sustainable source of fuel and is a competitive alternate to diesel engines. The glycerol that is produced as a by-product is generally discarded as waste and can be converted to green chemicals such as acetins to increase bio-diesel profitability. Acetins find application in fuel, food, pharmaceutical and leather industries. Batch experiments and analysis have been previously conducted for synthesis of acetins using glycerol esterification reaction aided by sulfated metal oxide catalysts (SO<sub>4</sub> <sup>2-</sup>/CeO<sub>2</sub>-ZrO<sub>2</sub>). The aim of this study was to optimize process parameters: effects of mole ratio of reactants (glycerol and acetic acid), catalyst concentration and reaction temperature to maximize glycerol conversion/acetin selectivity. The optimum conditions for this reaction were determined using response surface methodology (RSM) designed as per a five-level-three-factor central composite design (CCD). Statistica software 10 was used to analyze the experimental data obtained. The optimized conditions obtained were molar ratio - 1:12, catalyst concentration - 6 wt.% and temperature -90 ℃. A packed bed reactor was fabricated and column studies were performed using the optimized conditions. The breakthrough curve was analyzed.
Douglas de Britto,Marcia R. de Moura,Fauze A. Aouada,Flávia G. Pinola,Lícia M. Lundstedt,Odilio B. G. Assis,Luiz H. C. Mattoso 한국고분자학회 2014 Macromolecular Research Vol.22 No.12
Nanoencapsulation is a process suitable for use in reducing degradation of instable components. In thisstudy, chitosan and trimethyl chitosan with tripolyphosphate were used to nanoencapsulate vitamins C, B9, and B12. Analysis of the particle size showed that for a fix proportion of the polymer tripolyphosphate, the system showed awide variation in size with the amount of added vitamins: e.g., for vitamin B9, the particle size varied from 150±5nm to 809±150 nm. The zeta potential confirmed that trimethyl chitosan nanoparticles generally had a lower net positivecharge (20 mV) than chitosan nanoparticles (40 mV). The encapsulation efficiency was found to be dependenton nanoparticle structure and vitamin solubility, with vitamin B9 the most efficiently encapsulated (approximately40%). UV-Visible spectroscopy indicated different release profiles for vitamins C, B9, and B12 in a neutral PBSsolution with release rates of 36%, 52%, and 16% after 2, 24, and 4 h, respectively. In conclusion the liberation wasfound to be slower in acidic media.
Maria Isabel de Oliveira e Britto Villalobos,Thaisa Cristina Gomes Ferreira Leite,Samila Gonçalves Barra,Daniela Teresa Pinto da Cunha Werneche,Flavio Ricardo Manzi,Claudia Assunção e Alves Cardoso 대한영상치의학회 2017 Imaging Science in Dentistry Vol.47 No.1
Some complications can arise with the usage of local anesthesia for dental procedures, including the fracture of needles in the patient. This is a rare incident, usually caused by the patient’s sudden movements during anesthetic block. Its complications are not common, but can include pain, trismus, inflammation in the region, difficulty in swallowing, and migration of the object, which is the least common but has the ability to cause more serious damage to the patient. This report describes a case in which, after the fracture of the anesthetic needle used during alveolar nerve block for exodontia of the left mandibular third molar, the fragment moved significantly in the first 2 months, before stabilizing after the third month of radiographic monitoring.