Caracterização química e mineralógica do granítico Mairi, complexo Mairi, Chapada Diamantina, ne Brasil / Chemical and mineralogical characterization of the Mairi granite, Chapada Diamantina, ne Brazil

O granito Mairi, Paleoproterozoico, está inserido no Complexo Mairi, na escarpa oriental da Chapada Diamantina. Encontra-se na porção nordeste do Estado da Bahia, no município de Jacobina, na região nordeste do Brasil. Técnicas de mapeamento geológico, análise petrográfica, através de seções delgadas, química mineral por Difração de Raios-X e de rocha total por Fluorescência de Raios-X, auxiliaram para a identificação dos minerais constituintes da rocha, composição química semi-quantitativa da amostra e verificação das fases minerais do granito através da estrutura cristalina do litotipo. O Complexo Mairi possui influência magmática, sendo representado por granitóides paleoproterózoicos associados ao Complexo Itapicuru, Grupo Jacobina e a Formações Superficiais. A granitogênese caracteriza-se por rochas do tipo tonalito-trondhjemito-granodiorito, constituído por ortognaisses migmatíticos, graníticos, tonalíticos e associado a esse complexo, encontra-se os Complexos Saúde e Ipirá. A compilação de dados ratifica trabalhos anteriores quanto a classificação metaluminosa a peraluminosa do Granito Mairi, evidenciados por minerais hidratados, tanto na fase óxido, quanto na fase silicatos. Também, pode-se inferir que a granitogênese está associada a um ambiente tectônico pós-colisional e comparar o baixo potencial metalogenéticotico do granito. 

Effect of surface treatment and glazing in the two-body wear resistance of a hybrid ceramic after polymeric staining application

The present study evaluated the wear resistance of the characterization layer applied over a hybrid ceramic with different surface treatments against a zirconia antagonist. Eighty hybrid ceramic discs were prepared, polished and distributed in eight groups, according to the surface treatment before characterization and presence of a glaze layer (P, polished specimens–used as a reference; PG, polished specimens with glaze; E, acid etching; EG, acid etching + glaze; A, sandblasting; AG, sandblasting + glaze; S, self-etching silane; SG, self-etching silane + glaze). The specimens were subjected to physiological wear simulation with zirconia applicators (n = 10). The parameters for the wear simulation were: 15 N, horizontal movement of 6 mm, 1.7 Hz and 5000 cycles in distilled water. With the aid of a contact profilometer, Rz roughness parameter was analyzed in different periods of evaluation (after 0, 10, 100, 500, 1000 and 5000 cycles). Rz mean values were statistically analyzed using 3-way ANOVA (surface treatment × glaze presence × number of cycles), followed by Tukey test (α = 5%). ANOVA showed statistically significant differences among the groups considering the wear depth. And, significant interaction between the factors. However, as isolated factors, only surface treatment and number of cycles affected the staining wear rate (p < 0.05). Acid etching followed by glaze application was the most durable surface treatment to maintain the external staining on the hybrid ceramic surface when subjected to the two-body wear test

Effect of Different Surface Treatments on the Bond Strength of the Hybrid Ceramic Characterization Layer

Purpose: Using the microshear bond strength (pSBS) test, this study investigated the bond strength between a hybrid ceramic and the extrinsic characterization layer after different ceramic surface treatments. Materials and Methods: Hybrid ceramic blocks (Vita Enamic, Vita Zahnfabrik) were sectioned and randomly divided into 4 groups (N = 120) according to the surface treatment and aging (n = 15): P: polishing; E: acid etching with HF; A: aluminum oxide blasting; S: self-etching ceramic primer. The specimens were silanized, then cylinders of light-curing characterization material (Vita Enamic Stain, 1.6 mm diameter x 2 mm height) were fabricated, followed by glazing. The specimens were subsequently immersed in distilled water for 24 h and subjected to the pSBS test using a universal testing machine (load cell 0.5 mm/min, 50 kgf) or tested after thermocycling for 10,000 cycles in water (5°C-55°C). After treatment, the specimen surfaces were analyzed using SEM, with failure types defined as adhesive, predominantly adhesive, or cohesive. The data were analyzed by two-way ANOVA followed by Tukey's test (p 0.05). For groups P and A, a sharp decrease in SBS was observed. Conclusion: The absence of surface treatment drastically reduced the microshear bond strength between the ceramic and the characterization layer. Conditioning with 5% hydrofluoric acid for 60 s is the most suitable treatment for adhesion of the characterization layer to hybrid ceramic

Nitinol biliary stent versus surgery for palliation of distal malignant biliary obstruction

Background Curative resection of pancreatic and biliary malignancies is rare. Most tumors are inoperable at presentation, and palliation of jaundice often is the goal. Biliary decompression can be achieved by surgical diversion or endoscopic biliary stents. This study aimed to compare clinical outcomes between surgical bypass and endoscopic uncovered nitinol stents in the palliation of patients with malignant distal common bile duct obstruction. Methods A multicenter, retrospective, cohort study investigated 86 patients with inoperable malignant distal common bile duct strictures at tertiary referral centers in Medellin, Colombia. These patients had undergone surgery (group 1) or placement of an uncovered 30-Fr self-expandable nitinol stent produced locally in Medellin, Colombia (group 2). The main outcome measurements included cumulative biliary patency, hospital stay, and patient survival. Results The study enrolled 86 patients (mean age, 66 years; range, 43-78 years) including 40 patients in group 1 and 46 patients in group 2. Both groups were similar in terms of age, gender, liver metastasis, and diagnosis. Technical success was achieved for 38 patients in group 1 (95%) and 43 patients in group 2 (93%). Functional biliary decompression was obtained in for 35 of the surgical patients (88%) and 42 of the stented patients (91%). Group 2 had lower rates for procedure-related mortality (2 vs. 7.5%; p = 0.01), a lower frequency of early complications (8.7 vs. 45%; p = 0.02), and a shorter hospital stay (median, 6 vs. 12 days; p = 0.01). Recurrent jaundice occurred for three patients in group 1 (7.5%) and eight patients in group 2 (17.3%) (p = 0.198). Late gastric outlet obstruction occurred for 12.5% of the patients in group 1 and 13% of the patients in group 2 (p = 0.73). Despite the early benefits of stenting, no significant difference in the median overall survival between the two groups was found (group 1, 163 days; group 2, 178 days; p = 0.11). The limitations of this study included the small number of patients and the retrospective design. Conclusions Endoscopic stenting and surgery are effective palliation. The former is associated with fewer early complications and the latter with fewer late complications. Patients who do not qualify for curative resection may be better managed by stent placement. Surgery should be reserved for patients more likely to survive longer

Tratamento coadjuvante da arterite de Takayasu através de angioplastia transluminal percutânea com stents: relato de caso e revisão de literatura

Os autores fazem uma breve revisão de literatura sobre o uso coad-juvante de stents na arterite de Takayasu e apresentam um relato de caso de uma mulher jovem, 27 anos de idade, com quadro de cefaléia holocraniana acompanhada de náuseas, síncopes e tonturas. Concomitantemente apresentou turvação visual e claudicação de membros superiores. Entre as várias possibilidades, aventou-se a hipótese diagnóstica de arterite de Takayasu, confirmada posteriormente, sendo então realizado tratamento coadjuvante através de angioplastia transluminal percutânea com stents

A spectroelectrochemical investigation of the heme-based sensor DevS from Mycobacterium tuberculosis: a redox versus oxygen sensor

Tuberculosis is one of the oldest known infectious diseases, responsible for millions of deaths annually around the world. The ability of Mycobacterium tuberculosis (Mtb) to enter into a dormant state has been considered integral to the success of this bacterium as a human pathogen. One of the key systems involved in regulating the entrance into dormancy is the differentially expressed in virulent strain sensor protein (DevS) [(dormancy survival sensor protein (DosS)]. However, the physiological signal for DevS has remained unclear since it was first shown to be a heme-based sensor with conflicting reports on whether it is a redox or an oxygen sensor. To address this question and provide a better understanding of the electronic properties of this protein, we present here, for the first time, a series of spectroelectrochemistry measurements of the full-length holo DevS in anaerobic conditions as well as bound to CO, NO, imidazole (Imz), cyanide, and O-2. An interesting feature of this protein is its ability to bind Imz even in the ferrous state, implying small-molecule analogues could be designed as potential regulators. Nonetheless, a midpoint potential (E-m) value of +10 mV [vs normal hydrogen electrode (NHE)] for DevS as measured under anaerobic conditions is much higher than the expected cytosolic potential for Mtb or even within stimulated macrophages (similar to -270 mV vs NHE), indicating this sensor works in a reduced ferrous state. These data, along with the high oxygen affinity and very slow auto-oxidation rate of DevS, provides evidence that it is not a redox sensor. Overall, this study validates the biological function of DevS as an oxygen sensor directly involved in the dormancy/latency of Mtb

Effect of Finishing Protocols on the Surface Roughness and Fatigue Strength of a High-Translucent Zirconia

Purpose. In case of need for esthetical improvement of zirconia restorations, an individualization using extrinsic staining can be applied. This study aimed to evaluate the surface roughness and fatigue strength (survival) of high-translucency zirconia (3Y-TZP, YZ®HT, Vita Zanhfabrik) with extrinsic characterization and/or glaze. Methods. Sixty (60) zirconia discs (12 × 1.2 mm) were obtained, sintered, and randomly distributed among three groups (n = 20) according to the surface finishing protocol: C (control), C + G (extrinsic characterization followed by a glaze layer), and G (glaze layer). The surface roughness (Ra) was analyzed with a contact profilometer. Subsequently, the specimens were subjected to a fatigue load profile starting at 120 N during 20,000 cycles at 4 Hz frequency, with a 5% increase at each step until failure. The failed specimens were evaluated under a stereomicroscope. Surface roughness analysis was evaluated by using one-way ANOVA and post hoc Tukey tests (95%); while fatigue survival probability was analyzed with Kaplan–Meier and Mantel–Cox (log- rank, 95%). Results. One-way ANOVA revealed that surface roughness was affected by the finishing protocol, where C + G showed the highest mean value (0.46 ± 0.18 µm)A followed by G (0.30 ± 0.10 µm)B, and C (0.19 ± 0.02 µm)C. While for fatigue strength, the G protocol presented a higher mean value (243.00, and 222.36–263.63)A, followed by C + G (192.75 and 186.61–198.88)B and C (172.50 and 159.43–185.56)C. Conclusion. Surface finishing protocols modify the surface roughness and fatigue strength of high-translucent zirconia. Regardless of the surface roughness, both glazing protocols improved the ceramic fatigue strength, favoring the restoration’s long-term survival