Enhancing oil–solid and oil–water separation in heavy oil recovery by CO2-responsive surfactants

Interfacial properties are of critical importance to various separation applications. In heavy oil recovery, for example, a low oil–water interfacial tension (IFT) benefits the separation of heavy oil from their host rocks, which becomes problematic in the later stage of oil–water separation. CO₂-responsive surfactants were investigated to enhance the overall heavy oil recovery by switching their interfacial activity to the desired state in each stage. The surfactants at interfacially active state greatly enhanced the separation of heavy oil from hosting solids, as demonstrated by measuring contact angle and oil liberation using a custom-designed on-line visualization system. Meanwhile, the resulting heavy oil-in-water emulsions could also be easily demulsified by the bubbling of CO₂ gas, which switched off the interfacial activity of the surfactants. Furthermore, CO₂-responsive surfactants could be partially recycled in process water to improve sustainability, making CO₂-responsive surfactants to be promising chemical aids in heavy oil production and many other vital industries.     

Brazilian scientific production in science education

In the present study we analyzed the Brazilian scientific production in the area of science education. The study was structured on: data by research groups registered in Conselho Nacional de Desenvolvimento Científico e Tecnológico; analysis of the post-graduate strictu sensu programs; analysis of theses and dissertations linked to post-graduate programs; and papers in international databases. Our research was conducted strictly via world wide web, from December 2009 to September 2010. It was found that both number of research groups, researchers, post-graduate programs, thesis, dissertations and papers presented a marked increase, especially in the last decade (from 2000 onwards). The major research centers were found to be located in public universities from Brazilian southeast and south regions. However, it was observed a tendency of decentralization, due to a recent investment in new public universities in the other Brazilian regions. So, this study sought to present an overview of the scientific production about science education and we expect that this information can help to expand the vision about the development of this research area in Brazil.     

Heat stress affects the expression of key genes in the placenta,placental characteristics,and efficiency of Saanen goats and the survival and growth of their kids

Heat stress is detrimental during gestation; however, the effects of heat stress on goat placental characteristics and kid survival remain unclear. The objective of this study was to evaluate the effects of heat stress at final gestation on cortisol concentration, placenta characteristics, and the expression of genes related to placenta. Forty-six primiparous and multiparous Saanen goats were subjected to control (CT; under a thermoneutral environment: air temperature between 12°C and 25°C and the relative humidity from 45 to 73%, n = 23) or heat stress (HS; under a climatic chamber: air temperature at 37°C and the relative humidity at 60 to 70% from 0800 to 1600 h, n = 23) from the last 60 d of pregnancy until the first colostrum suckling. The heat challenge imposed on HS goats during the prepartum period increased their rectal temperature, respiratory frequency, and cortisol levels in plasma and amniotic fluid versus CT goats. In the placenta, HS treatment also increased the expression of the HSPA1A gene. Heat-stressed goats also showed significantly lower expression of HSD11B2 and greater expression of MC2R and NR3C1 than CT goats, suggesting that heat stress decreased the effectiveness by which the HSD11B2 enzyme converts cortisol to cortisone and increased placental responsiveness to cortisol. The HS goats took longer to release the placenta with lighter placental cotyledons, and HS goats had a lower ratio between the kid's weight at birth and placenta weight than CT goats. There was no treatment effect on the kids' survival or weights at birth, but the kids from goats subjected to HS presented lesser cortisol concentration and greater mortality rates at weaning than kids from CT goats. Finally, the overexpression of HSPA1A by HS goats suggests a protective response of placenta. However, the heat stress negatively affected the placenta's expulsion length, placental cotyledons number, weight and area, the ratio between kid's weight and placenta weight, and cortisol signaling. Indeed, the upregulation of MC2R and NR3C1 and downregulation of HSD11B2 on placenta caused by heat stress were associated with greater cortisol concentrations in the amniotic fluid of HS goats. Although HS and CT kids had adequate weights and survival rate during the first weeks of life, the heat stress increased the mortality at weaning of HS kids versus CT kids, suggesting that the heat stress effect persists and can change the ability of kids to respond to weaning challenge.     

Thixoforging of 332 aluminum alloy in a mechanical eccentric press

Journal of Materials Science - This study sought to analyze the semi-solid behavior of commercial 332 aluminum alloy during thixoforming in a mechanical eccentric press (thixoforging). The...     

Polymeric Nanoparticle-Based Photodynamic Therapy for Chronic Periodontitis in Vivo

Antimicrobial photodynamic therapy (aPDT) is increasingly being explored for treatment of periodontitis. Here, we investigated the effect of aPDT on human dental plaque bacteria in suspensions and biofilms in vitro using methylene blue (MB)-loaded poly(lactic-co-glycolic) (PLGA) nanoparticles (MB-NP) and red light at 660 nm. The effect of MB-NP-based aPDT was also evaluated in a clinical pilot study with 10 adult human subjects with chronic periodontitis. Dental plaque samples from human subjects were exposed to aPDT—in planktonic and biofilm phases—with MB or MB-NP (25 µg/mL) at 20 J/cm² in vitro. Patients were treated either with ultrasonic scaling and scaling and root planing (US + SRP) or ultrasonic scaling + SRP + aPDT with MB-NP (25 µg/mL and 20 J/cm²) in a split-mouth design. In biofilms, MB-NP eliminated approximately 25% more bacteria than free MB. The clinical study demonstrated the safety of aPDT. Both groups showed similar improvements of clinical parameters one month following treatments. However, at three months ultrasonic SRP + aPDT showed a greater effect (28.82%) on gingival bleeding index (GBI) compared to ultrasonic SRP. The utilization of PLGA nanoparticles encapsulated with MB may be a promising adjunct in antimicrobial periodontal treatment.     

Influence of Drying Techniques on the Characteristics of Chitosan and the Quality of Biopolymer Films

In this work, spouted bed and tray-drying techniques were employed at different drying air temperatures to produce dried chitosan, and the chitosan powder was used to produce biofilms. The products obtained from each drying technique were compared in relation to quality aspects (molecular weight, lightness, and hue angle). The results found for chitosan in spouted bed drying (90°C) showed lower alteration and best quality aspects in relation to the chitosan powder. However, in tray drying under the best condition (60°C) the chitosan molecular weight increased about 50% in relation to the initial value and browning was observed. The biofilms produced from chitosan dried in the spouted bed showed the best mechanical properties (tensile strength of 42 MPa and elongation of 29%) and lower water vapor permeability (3.95 g mm m^?2 kPa^?1 day^?1).     

Ant colony optimisation for tree-searching-based synthesis of monopulse array antenna

The design of simple feed networks is of great interest in synthesising monopulse radar array antennas in order to reduce the complexity of the antenna architecture, the costs as well as the occupied physical space (e.g. on aircraft). Sub-arraying techniques have been proposed to properly address such a task. Starting from the formulation of the sub-arraying problem in terms of a combinatorial one, the final compromise solution is obtained by looking for the minimum cost path inside a binary tree graph through an ant colony optimiser.     

Structural Characterization of Doped GaSb Single Crystals by X-ray Topography

We characterized GaSb single crystals containing different dopants (Al, Cd, and Te), grown by the Czochralski method, using x-ray topography and high-angular-resolution x-ray diffraction. Lang topography revealed dislocations parallel and perpendicular to the crystal surface. Double-crystal GaSb 333 x-ray topography showed dislocations and vertical stripes that could be associated with circular growth bands. We compared our high-angular- resolution x-ray diffraction measurements (rocking curves) with findings predicted by the dynamical theory of x-ray diffraction. These measurements show that our GaSb single crystals have a relative variation in the lattice parameter (Δd/d) on the order of 10⁻⁵. This means that they can be used as electronic devices (e.g., detectors) and as x-ray monochromators.     

Chromogenic anionic chemosensors based on protonated merocyanine solvatochromic dyes: Influence of the medium on the quantitative and naked-eye selective detection of anionic species

Three merocyanine solvatochromic dyes, Brooker's merocyanine, Reichardt's dye and 4-(2,4,6-triphenylpyridinium-1-yl)phenolate were solubilized in acetonitrile. Although solutions of each of the compounds are colored, the color disappears after protonation. Addition of various anions to solutions of the protonated dyes revealed that only CN^?, F^?, and H₂PO₄^? led to the reappearance of the original color of protonated Reichardt's dye, and only CN^? and F^? ions caused the original color of the solutions containing the other two protonated dyes to reappear. Addition of small amounts of water to solutions containing the protonated compounds made them useful only for detecting CN^? among all the other anions. A model was used to explain the experimental results, which considers proton transfer from the protonated dye to the anion through three dye:anion stoichiometries, namely 1:1, 1:2, and 1:3.     

Enhanced visualization of histological samples with an adjustable RGB contrast system with application for tissue used in photodynamic therapy

The analysis of histological sections has long been a valuable tool in the pathological studies. The interpretation of tissue conditions, however, relies directly on visual evaluation of tissue slides, which may be difficult to interpret because of poor contrast or poor color differentiation. The Chromatic Contrast Visualization System (CCV) combines an optical microscope with electronically controlled light-emitting diodes (LEDs) in order to generate adjustable intensities of RGB channels for sample illumination. While most image enhancement techniques rely on software post-processing of an image acquired under standard illumination conditions, CCV produces real-time variations in the color composition of the light source itself. The possibility of covering the entire RGB chromatic range, combined with the optical properties of the different tissues, allows for a substantial enhancement in image details. Traditional image acquisition methods do not exploit these visual enhancements which results in poorer visual distinction among tissue structures. Photodynamic therapy (PDT) procedures are of increasing interest in the treatment of several forms of cancer. This study uses histological slides of rat liver samples that were induced to necrosis after being exposed to PDT. Results show that visualization of tissue structures could be improved by changing colors and intensities of the microscope light source. PDT-necrosed tissue samples are better differentiated when illuminated with different color wavelengths, leading to an improved differentiation of cells in the necrosis area. Due to the potential benefits it can bring to interpretation and diagnosis, further research in this field could make CCV an attractive technique for medical applications.