Marcio Mesquita Barros

Polymeric dental adhesives require the formation of densely crosslinked network structures to best ensure mechanical strength and durability in clinical service. Monomeric precursors to these materials typically consist of mixtures of hydrophilic and hydrophobic components that potentially undergo phase separation in the presence of low concentrati...

Due to the scarcity of information about patterns of spermatogenesis in bats, this study aimed to provide information on the testicular activity of the bat Sturnira lilium along the annual seasons. Thus, a series of morphometrical and stereological analyses were made using the testes of adult S. lilium in order to achieve a better understanding of...

Polymerization-induced phase separation from an all-monomeric system by direct copolymerization offers the formation of heterogeneous polymeric structures without reliance on polymer blends, block copolymers, or interpenetrating polymer networks. This study examines the potential for the formation of compositional heterogeneity in copolymer network...

Knowledge of the stages that compose the seminiferous epithelium cycle (SEC) and determination of the duration of spermatogenic processes are fundamental for the accurate quantification of the dynamics of spermatogenesis. The aim of this study was to characterize the stages that compose the SEC of the bat Sturnira lilium, including evaluation of th...

A series of nanogel compositions were prepared from urethane dimethacrylate (UDMA) and isobornyl methacrylate (IBMA) in the presence of a thiol chain transfer agent. The linear oligomer of IBMA was synthesized by a similar solution polymerization technique. The nanogels were prepared with different crosslinker concentrations to achieve varied branc...

The aim of this study was to evaluate the effect of different rates of nitrogen on production and quality of watermelon 'Crimson Sweet'. This research was conducted in the experimental area of the Federal University of Roraima, Boa Vista, from January to April 2010. The experimental design was in randomized blocks with 4 replications. The treatment...

Moisture/Temperature Effects on Cationic/Radical Dental Composite Polymerizations Objective: Analyze the influence of ambient conditions, such as oral cavity humidity/temperature on polymerization of dimethacrylate or oxirane-based dental composites. Methods: 250m films of EsthetXHD (EHD, dimethacrylate) or FiltekP90 (P90, oxirane-based) were a...

The organophosphorous (OP) pesticide fenthion is widely used in commercial fruit industry and orchards in South America. Among the metabolic effects in mammals caused by fenthion, hyperglycemia occurs via the activation of hepatic metabolic pathways, which may interfere with the function of several organs and systems. The purpose of this study was...

A new class of insecticide derived from fermentation of Sacharopolyspora spinosa - spinosad, has been indicated as being of low toxicity and a natural alternative to classical pesticides. In order to elucidate several aspects related to the morphophysiological changes induced by spinosad in Artibeus lituratus, the effects of a seven-day administrat...

Chelonoidis Dcarbonaria and C. denticulata are two tortoises which are widely distributed Brazil. Although they occur sympatrically in different areas, C. carbonaria prefers open areas, while C. denticulata chooses forest areas. Significant morphological variations can be observed in these species due to the fact that they occupy a vast and environ...

Forest fragmentation associated with the expansion of human development is a phenomenon that occurs worldwide. Studies reveal that there have been both a decline in species diversity and a decrease in Neotropical bat population size because of habitat loss. The aim of this study was to investigate whether human action has been affecting the food av...

Current challenges in adhesive dentistry include over-hydrophilic bonding formulations, which facilitate water percolation through the hybrid layer and result in unreliable bonded interfaces. This study introduces nanogel-modified adhesives as a way to control the material's hydrophobic character without changing the basic monomer formulation (keep...

The aim of this paper was to evaluate the effect of five nitrogen doses (50, 100, 150, 200 and 250 kg ha-1) on yield components and yield of watermelon cv. Crimson Sweet. The experiment was carried out under field conditions at Boa Vista, RR, on January to April 2010, under yellow oxisol. The experimental design was randomized blocks with four repl...

The present report describes the occurrence of skin metastasis in a dog with primary renal carcinoma. The clinical findings included progressive weight loss, inappetence, palpable abdominal mass and cutaneous tumor. The histopathological examination was carried out after unilateral nephrectomy and was confirmed by immunohistochemistry. The immunohi...

O trabalho objetivou avaliar o rendimento da alface (Lactuca sativa L.) cv. “Verônica’ cultivada sob ambiente protegido, em função de doses de nitrogênio aplicadas via fertirrigação. O delineamento estatístico foi de blocos casualizados, com cinco tratamentos (0; 60; 120; 180 e 240 kg ha-1 de N) e quatro repetições. A fonte de N foi a uréia, dividi...

Reactive nanogel additives have been shown to enhance bulk wet strength of dental adhesive resins. Objective: Investigate the effects of composition, molecular weight (MW) and intrinsic viscosity (IV) of nanogels as organic nanofillers on dentin shear bond strengths (SBS) in etch-and-rinse dentin adhesives. Methods: Five nanogels with co-polymeriza...

Nanogel additives have been used to significantly reduce polymerization shrinkage and stress in polymeric dental materials. Objectives: This study compares the synthesis and resultant properties of nanogel particles prepared with varied amounts of chain transfer agent (CTA) using photopolymerization and thermal polymerization techniques. Methods:...

Objectives: Polymerization stress reduction is critical to prolonging the clinical performance and lifetime of composite restoratives. Dental resins and composites have been modified by the addition of nanogel polymeric particles as a route to heterogeneous materials with reduced polymerization shrinkage and stress. This study investigates how nano...

Addition of nanogel prepolymer particles to dental monomers has been used to reduce polymerization shrinkage and stress. Objective: Physical isolation of photoinitiator (PI) within nanogel particles dispersed in and swollen by dental monomers can spatially localize initial polymerization to potentially delay macrogelation and vitrification while en...

This study demonstrates the effects of nano-scale prepolymer particles as additives to model dental monomer and composite formulations. Discrete nanogel particles were prepared by solution photopolymerization of isobornyl methacrylate and urethane dimethacrylate in the presence of a chain transfer agent, which also provided a means to attach reacti...

Metabolic adaptations induced by 24 and 48 hours of fasting were investigated in male and female insectivorous bats (Molossus molossus Pallas, 1766). For this purpose, plasma glucose, non esterified fatty acids (NEFA), glycogen, protein and lipids concentrations in liver and muscles were obtained. Data presented here demonstrate that fed bats showe...

Objectives: With the longer-term goal of designing new heterogeneous copolymer systems, the current study focuses on development of new mono- and di-methacrylate monomers with extended aliphatic structures. The relationship between monomer structure and its homo- or co-polymerization kinetics is examined here. Methods: Several versions of isosteary...

Free radical photocuring is used extensively due to the inherent advantages of temporal and spatial control over polymerization. Unlike ionic polymerizations, where direct termination reactions between polymer chains are restricted, radical polymerizations are prone to various biradical reactions leading to efficient termination. As a result, radic...

Objectives: This investigation probes the potential for structurally and functionally varied thiol chain-transfer agents (CTA) to delay gelation and reduce polymerization stress in model dimethacrylate restorative resins. Methods: Ethoxylated bisphenol A dimethacrylate (BisEMA; control) was combined with mono-, di- or tetra-thiols: dodecanethiol...

Hepatocellular carcinoma (HCC) is the fifth most common cancer in the world and the third leading cause of cancer-related death. In this study, we sought to assess the outcome of patients with HCC who underwent orthotopic liver transplantation (OLT) in a center in the northeast of Brazil. Between May 2002 and July 2008, 294 OLTs were performed at o...

Hepatic artery thrombosis (HAT) is a serious complication after orthotopic liver transplantation (OLT) and remains a significant cause of graft loss. HAT following OLT has been reported in 3% to 9% of patients. Among the surgical factors considered to be associated with HAT, arterial reconstruction might be the most important. The goal of this stud...

Disperse blue 106 is one of the most important allergenic textile dyes. We reviewed all the patients that proved to be allergic to this dye, in 10 contact clinics, in Portugal, from 01/2000 to 06/2003. In the first 2 years disperse blue 106 was only tested in suspected cases, while in 2002/2003 it was routinely tested in our standard series. A tota...

Arterial complications after liver transplantation are frequent. Hepatic artery thrombosis (HAT) is usually associated with biliary complications. Herein we have reported a case of a patient who was admitted for jaundice, itch, and elevated aspartate aminotransferase and alanine aminotransferase levels at 6 weeks after liver transplantation. HAT as...

Sequential or domino liver transplantation is a well-established procedure for patients with familial amyloidotic polyneuropathy (FAP). Donation for domino liver transplantation imposed the resection of the inferior vena cava along with the liver, requiring complete suprarenal vena cava clamping and usually the use of venovenous bypass. We describe...

Belzer and Collins are solutions used in liver transplantation. The purpose of this study was to compare liver function after utilization of two different schemes of graft preservation using both solutions. Between December 2004 and September 2005, 43 liver transplantations were performed. Twenty-three of these used 2 L of Collins solution and 2 L...

The authors report a study allergic contact dermatitis in 329 Portuguese children of 14 years or younger. 170 children (64 male and 106 female) reacted to 1 or more allergens. Most of these were in the 11–14 years group. The main allergens were nickel, thimerosal, cobalt, mercury, fragrance-mix and potassium dichromate. Nickel reactivity predominat...

6 female patients with allergic contact dermatitis from textile dyes are described. Lesions were confined to areas in direct contact with the offending garment, mainly where friction and/or pressure occurred. Patch tests were positive to 2 or more disperse dyes. Thin-layer chromatography was carried out on the dyes extracted from fabrics of 3 patie...

The authors report a study of allergic contact dermatitis in 329 Portuguese children of 14 years or younger. 170 children (64 male and 106 female) reacted to 1 or more allergens. Most of these were in the 11-14 years group. The main allergens were nickel, thimerosal, cobalt, mercury, fragrance-mix and potassium dichromate. Nickel reactivity predomi...

562 schoolchildren from Oporto were patch tested with the standard series of the Portuguese Contact Dermatitis Group (GPEDC). 13.3% of the children had positive reactions, the most common being to neomycin, thimerosal, para-tertiary-butylphenol-formaldehyde (PTBPF) resin and fragrance-mix. Thus contact allergy in children seems not to be as unusual...

Let M be a complete 4n-dimensional quaternion Kaehlerian manifold isometrically immersed in the (4 n + d (-dimensional Euclidean space. In this note we prove that if d < n, then M is a Riemannian product Qm × P, where Qm is the m-dimensional quaternion Euclidean space (m ≥ n-d) and P is a Ricci flat quaternion Kaehlerian manifold.

Let M be a complete 4n-dimensional quaternion Kaehlerian manifold isometrically immersed in the (4n + d)-dimensional Euclidean space. In this note we prove that if $d

Some characterizations of complex quadrics in terms of the spectrum are given.

The authors study quaternion CR-submanifolds (i.e. submanifolds which admit a differentiable quaternion distribution D such that its orthogonal complementary distribution is totally real). The integrability of the two natural distributions of such a submanifold is studied. Then, some results are obtained when the submanifold admits a totally geodes...