Determination of catechin in green tea using a catechol oxidase biomimetic sensor

A catechol oxidase biomimetic sensor, based on a novel copper(II) complex, was developed for the determination of catechin in green tea and the results were compared with those obtained by capillary electrophoresis. The dinuclear copper(II) complex, [Cu2(HL)(µ-CH3COO)](ClO4), containing the ligand N,N-[bis-(2-pyridylmethyl)]-N',N'-[(2-hydroxybenzyl)(2-hydroxy-3,5-di-tert-butylbenzyl)]-1,3-propanediamine-2-ol (H3L), was synthesized and characterized by IR, ¹H NMR and elemental analysis. The best conditions for the optimization of the biomimetic sensor were established by square wave voltammetry. The best performance for this sensor was obtained in 75:15:10% (m/m/m) of the graphite powder:nujol:copper(II) complex, 0.05 mol L-1 phosphate buffer solution (pH 7.5) and frequency, pulse amplitude, scan increment at 30 Hz, 80 mV, 3.3 mV, respectively. The analytical curve was linear in the concentration range 4.95 × 10-6 to 3.27 × 10-5 mol L-1 (r = 0.9993) with a detection limit of 2.8 × 10-7 mol L-1. This biomimetic sensor demonstrated long-term stability (9 months; 800 determinations) and reproducibility with a relative standard deviation of 3.5%. The recovery of catechin from green tea samples ranged from 93.8 to 106.9% and the determination, compared with that obtained using capillary electrophoresis, was found to be acceptable at the 95% confidence level

Di-μ-chlorido-bis­[chlorido(1,4,6-trimethyl-6-nitro-1,4-diazepine)copper(II)]

The title neutral copper complex, [Cu2Cl4(C8H17N3O2)2], shows a binuclear center with a Cu—(μ-Cl)2—Cu core, in which each copper ion is coordinated by the N,N,O donor atoms of the tridentate ligand 1,4,6-trimethyl-6-nitro-1,4-diazepine (meaaz-NO2) and three chloride exogenous ligands. Each metal ion is facially coordinated by meaaz-NO2 through N,N,O donor atoms, whereas two bridging and one terminal chloride ions occupy the other face of the highly Jahn–Teller-distorted octa­hedron. Two N atoms from tertiary amine groups of the meaaz-NO2 ligand and two exogenous Cl atoms with short Cu—N and Cu—Cl distances define the equatorial plane. The coordination around each CuII ion is completed by another Cl atom and an O atom from the NO2 group, in the axial positions. The binuclear complex exhibits a centrosymmetric structure with point symmetry

A realidade das aulas de Educação Física de uma escola da zona rural no interior de Minas Gerais

Este estudo objetivou analisar a realidade das aulas de Educação Física de uma escola da zona rural do interior de MG. Foi realizado um estudo de campo com abordagem quali-quantitativa com coleta de dados por meio de dois questionários, um aplicado a 24 (n=32,87%) alunos do ensino fundamental II, e outro a professora. Os dados foram tratados a partir de uma análise estatística descritiva. Na percepção da professora o número de aulas são poucas, uma por semana, o que vai de encontro ao pensamento dos alunos (95,83%). Os espaços e materiais da escola, mais de 50% julgam ser ruim, o que também é relatado pela professora. 52% vêm nas aulas de Educação Física uma forma de se distraírem, divertirem e recrearem. Conclui-se que na perspectiva dos alunos, a realidade das aulas de Educação Física na escola não os agrada

Thermal degradation kinetics and lifetime prediction of cellulose biomass cryogels reinforced by its pyrolysis waste

Degradation kinetics is an important tool in order to understand and improve energy conversion and the final application of a material. Cellulose cryogels (CC) are a new class of materials that can be reinforced by several types of particle, including biochar. Apart from it, degradation kinetics and lifetime prediction of biomass cellulose cryogels reinforced by cellulose pyrolysis waste (BC) has been investigated using TG techniques and iso-conversional model free methods. Additionally, the same study was applied to cellulose cryogels reinforced by graphene nanoplatelets (NPG) to compare the behavior of a filler from waste (BC) and a noble filler (NPG). Furthermore, the influence of the addition of the fillers into the cellulose biomass were evaluated in terms of thermal stability and crystallinity. BC and GNP led to higher values of activation energies (Ea) calculated from model-free isoconversional methods and all samples degraded in two-steps. Finally, lifetime prediction was successfully applied and the CC cryogel became more stable over time, maintaining almost 80% of the mass for 1 year exposed at 180 °C. The results of this study shown that only cellulose biomass cryogels are more suitable to produce thermal insulators due to it higher thermal stability

Deep neck infection after third molar extraction: A case report

Deep neck infections are associated with high morbidity rates in dentistry. Early diagnosis and intervention play an essential part in decreasing morbidity rates. The present study aims to report a case of odontogenic deep neck infection after third molar extraction. A 51-year-old male patient underwent extraction of the mandibular right third molar. Seven days later, the patient developed symptoms and signs of progressive infection. Laboratorial and radiologic examinations in association with clinical investigations confirmed deep neck infection. Extraoral drainage was performed under orotracheal intubation. Postoperative laboratory tests and clinical examinations revealed signs of complete remission within a follow-up period of 10 days. Considering the invasive nature of pathogens related to deep neck infections, it is possible to infer that a combination of accurate diagnosis and early intervention plays an essential role in the field of maxillofacial surgery and pathology