Simulations of extensional flow in microrheometric devices

We present a detailed numerical study of the flow of a Newtonian fluid through microrheometric devices featuring a sudden contraction–expansion. This flow configuration is typically used to generate extensional deformations and high strain rates. The excess pressure drop resulting from the converging and diverging flow is an important dynamic measure to quantify if the device is intended to be used as a microfluidic extensional rheometer. To explore this idea, we examine the effect of the contraction length, aspect ratio and Reynolds number on the flow kinematics and resulting pressure field. Analysis of the computed velocity and pressure fields show that, for typical experimental conditions used in microfluidic devices, the steady flow is highly three-dimensional with open spiraling vortical structures in the stagnant corner regions. The numerical simulations of the local kinematics and global pressure drop are in good agreement with experimental results. The device aspect ratio is shown to have a strong impact on the flow and consequently on the excess pressure drop, which is quantified in terms of the dimensionless Couette and Bagley correction factors. We suggest an approach for calculating the Bagley correction which may be especially appropriate for planar microchannels

d=3 Bosonic Vector Models Coupled to Chern-Simons Gauge Theories

We study three dimensional O(N)_k and U(N)_k Chern-Simons theories coupled to a scalar field in the fundamental representation, in the large N limit. For infinite k this is just the singlet sector of the O(N) (U(N)) vector model, which is conjectured to be dual to Vasiliev's higher spin gravity theory on AdS_4. For large k and N we obtain a parity-breaking deformation of this theory, controlled by the 't Hooft coupling lambda = 4 \pi N / k. For infinite N we argue (and show explicitly at two-loop order) that the theories with finite lambda are conformally invariant, and also have an exactly marginal (\phi^2)^3 deformation. For large but finite N and small 't Hooft coupling lambda, we show that there is still a line of fixed points parameterized by the 't Hooft coupling lambda. We show that, at infinite N, the interacting non-parity-invariant theory with finite lambda has the same spectrum of primary operators as the free theory, consisting of an infinite tower of conserved higher-spin currents and a scalar operator with scaling dimension \Delta=1; however, the correlation functions of these operators do depend on lambda. Our results suggest that there should exist a family of higher spin gravity theories, parameterized by lambda, and continuously connected to Vasiliev's theory. For finite N the higher spin currents are not conserved.Comment: 34 pages, 29 figures. v2: added reference

Microfluidic systems for the analysis of the viscoelastic fluid flow phenomena in porous media

In this study, two microfluidic devices are proposed as simplified 1-D microfluidic analogues of a porous medium. The objectives are twofold: firstly to assess the usefulness of the microchannels to mimic the porous medium in a controlled and simplified manner, and secondly to obtain a better insight about the flow characteristics of viscoelastic fluids flowing through a packed bed. For these purposes, flow visualizations and pressure drop measurements are conducted with Newtonian and viscoelastic fluids. The 1-D microfluidic analogues of porous medium consisted of microchannels with a sequence of contractions/ expansions disposed in symmetric and asymmetric arrangements. The real porous medium is in reality, a complex combination of the two arrangements of particles simulated with the microchannels, which can be considered as limiting ideal configurations. The results show that both configurations are able to mimic well the pressure drop variation with flow rate for Newtonian fluids. However, due to the intrinsic differences in the deformation rate profiles associated with each microgeometry, the symmetric configuration is more suitable for studying the flow of viscoelastic fluids at low De values, while the asymmetric configuration provides better results at high De values. In this way, both microgeometries seem to be complementary and could be interesting tools to obtain a better insight about the flow of viscoelastic fluids through a porous medium. Such model systems could be very interesting to use in polymer-flood processes for enhanced oil recovery, for instance, as a tool for selecting the most suitable viscoelastic fluid to be used in a specific formation. The selection of the fluid properties of a detergent for cleaning oil contaminated soil, sand, and in general, any porous material, is another possible application

Keratocystic odontogenic tumor overexpresses invadopodia-related proteins, suggesting invadopodia formation

OBJECTIVE: Keratocystic odontogenic tumor (KOT) is an odontogenic neoplasm that shows aggressive clinical behavior and local invasiveness. Invadopodia are actin-rich cellular protrusions exhibiting proteolytic pericellular activity, thereby inducing focal invasion in neoplastic cells and increasing neoplasms aggressiveness. Thus, this study aimed to evaluate immunoexpression of invadopodia-related proteins, cortactin, MT1-MMP, Tks4, and Tks5, in KOT. STUDY DESIGN: Immunohistochemistry of 16 cases of KOT, eight cases of calcifying cystic odontogenic tumor (CCOT), and eight samples of the oral mucosa (OM) was carried out to assess the expression of the above described invadopodia-related proteins in the basal and suprabasal layer. RESULTS: KOT samples showed higher and significant immunoexpression of cortactin, MT1-MMP, TKs4, and TKs5 compared with the CCOT and OM samples. Significant expression of all these proteins was observed in the basal layer compared with the suprabasal layer in KOT. CONCLUSIONS: Overexpression of cortactin, MT1-MMP, TKs4, and TKs5 was observed in KOT compared with samples of CCOT and OM. These proteins were also overexpressed in the basal over the suprabasal layer of KOT samples. Taken together, these results suggest the participation of invadopodia-related proteins on the pathogenesis of this lesion

Identification of novel esterase-active enzymes from hot environments by use of the host bacterium Thermus thermophilus

Functional metagenomic screening strategies, which are independent of known sequence information, can lead to the identification of truly novel genes and enzymes. Since E. coli has been used exhaustively for this purpose as a host, it is important to establish alternative expression hosts and to use them for functional metagenomic screening for new enzymes. In this study we show that Thermus thermophilus HB27 is an excellent screening host and can be used as an alternative provider of truly novel biocatalysts. In a previous study we constructed the mutant strain BL03 that was no longer able to grow on defined minimal medium supplemented with tributyrin as the sole carbon source and could be used as a host to screen for metagenomic DNA fragments that could complement growth on tributyrin. Several thousand single fosmid clones from thermophilic metagenomic libraries from heated compost and hot spring water samples were subjected to a comparative screening for esterase activity in both T. thermophilus strain BL03 and E. coli EPI300. We scored a greater number of active clones in the thermophilic bacterium than in the mesophilic E. coli. From all clones functionally screened in E. coli, only two thermostable α/β-fold hydrolase enzymes with high amino acid sequence similarity to already characterized enzymes were identifiable. In contrast, five further fosmids were found that conferred lipolytic activities in T. thermophilus. Four open reading frames (ORFs) were found which did not share significant similarity to known esterase enzymes. Two of the genes were expressed in both hosts and the novel thermophilic esterases, which based on their primary structures could not be assigned to known esterase or lipase families, were purified and preliminarily characterized. Our work underscores the benefit of using additional screening hosts other than E. coli for the identification of novel biocatalysts with industrial relevance

Nanostructured 3D Constructs Based on Chitosan and Chondroitin Sulphate Multilayers for Cartilage Tissue Engineering

Nanostructured three-dimensional constructs combining layer-by-layer technology (LbL) and template leaching were processed and evaluated as possible support structures for cartilage tissue engineering. Multilayered constructs were formed by depositing the polyelectrolytes chitosan (CHT) and chondroitin sulphate (CS) on either bidimensional glass surfaces or 3D packet of paraffin spheres. 2D CHT/CS multi-layered constructs proved to support the attachment and proliferation of bovine chondrocytes (BCH). The technology was transposed to 3D level and CHT/CS multi-layered hierarchical scaffolds were retrieved after paraffin leaching. The obtained nanostructured 3D constructs had a high porosity and water uptake capacity of about 300%. Dynamical mechanical analysis (DMA) showed the viscoelastic nature of the scaffolds. Cellular tests were performed with the culture of BCH and multipotent bone marrow derived stromal cells (hMSCs) up to 21 days in chondrogenic differentiation media. Together with scanning electronic microscopy analysis, viability tests and DNA quantification, our results clearly showed that cells attached, proliferated and were metabolically active over the entire scaffold. Cartilaginous extracellular matrix (ECM) formation was further assessed and results showed that GAG secretion occurred indicating the maintenance of the chondrogenic phenotype and the chondrogenic differentiation of hMSCs

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

Resposta terapêutica e profilática com ferro e ácido fólico na anemia em crianças de creches públicas em Goiânia, Goiás, Brasil: ensaio clínico randomizado

The objective of this study was to assess the prevalence of anemia and the therapeutic and prophylactic response to ferrous sulfate and folic acid. A double-blind, randomized, controlled clinical trial was conducted with 196 children 6 to 24 months of age enrolled in municipal daycare centers in Goiânia, Goiás State, Brazil. The children were assigned to two treatment groups that received a daily dose (5 times a week) of either 4.2mg/kg/day of ferrous sulfate + folic acid (50µg) or 4.2mg/kg/day of ferrous sulfate + folic acid placebo. One of the prevention groups received 1.4mg/kg/day of ferrous sulfate + folic acid (50µg/day) and the other 1.4mg/kg/day of ferrous sulfate + folic acid placebo. Supplementation lasted approximately three months. Baseline anemia prevalence was 56.1% (95%CI: 48.9-63.1). After treatment, anemia prevalence in the folic acid group (14%) was lower than in the placebo group (34.9%) (p = 0.02). After prophylaxis in the non-anemic children, the incidence of anemia did not differ between the groups, but there was an increase in hemoglobin level in the folic acid group (p = 0.003). Iron plus folic acid was effective for the treatment of anemia and improvement of hemoglobin level in non-anemic children.Avaliar a prevalência de anemia e a resposta terapêutica e profilática do sulfato ferroso e ácido fólico. Realizou-se um ensaio clínico controlado randomizado, duplo-cego, com 196 crianças de 6 a 24 meses, dos Centros Municipais de Educação Infantil de Goiânia, Goiás, Brasil. As crianças foram alocadas em dois grupos de tratamento que receberam dose diária (5x/semana) com 4,2mg/kg/dia de sulfato ferroso + ácido fólico (50µg) ou 4,2mg/kg/dia de sulfato ferroso + placebo de ácido fólico. Um dos grupos de prevenção recebeu 1,4 mg/kg/dia de sulfato ferroso + ácido fólico (50µg/dia) e o outro 1,4mg/kg/dia de sulfato ferroso + placebo de ácido fólico. A suplementação durou cerca de três meses. A prevalência de anemia inicial foi de 56,1% (IC95%: 48,9-63,1). Após o tratamento, a prevalência de anemia no grupo ácido fólico (14%) foi menor que no grupo placebo (34,9%; p = 0,02). Após profilaxia dos não anêmicos, a incidência de anemia não diferiu entre os grupos, porém, houve incremento da hemoglobina no grupo ácido fólico (p = 0,003). O ferro associado com ácido fólico foi eficaz no tratamento da anemia e na melhoria da hemoglobina nos não anêmicos.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de Goiás Faculdade de NutriçãoUniversidade Federal de São Paulo (UNIFESP)Universidade Federal de Goiás Instituto de Patologia Tropical e Saúde PúblicaVila São José Bento CotolengoUNIFESPSciEL

Continuous fungal treatment of non-sterile veterinary hospital effluent: pharmaceuticals removal and microbial community assessment

Source point treatment of effluents with a high load of pharmaceutical active compounds (PhACs), such as hospital wastewater, is a matter of discussion among the scientific community. Fungal treatments have been reported to be successful in degrading this type of pollutants and, therefore, the white-rot fungus Trametes versicolor was applied for the removal of PhACs from veterinary hospital wastewater. Sixty-six percent removal was achieved in a non-sterile batch bioreactor inoculated with T. versicolor pellets. On the other hand, the study of microbial communities by means of DGGE and phylogenetic analyses led us to identify some microbial interactions and helped us moving to a continuous process. PhAC removal efficiency achieved in the fungal treatment operated in non-sterile continuous mode was 44 % after adjusting the C/N ratio with respect to the previously calculated one for sterile treatments. Fungal and bacterial communities in the continuous bioreactors were monitored as well.Authors want to acknowledge the UAB veterinary hospital staff for their kind permission and help for the samplings. This work has been funded by the Spanish Ministry of Economy and Competitiveness and FEDER (projects CTM2013-48545-C2 and AIB2010PT-00169) and supported by the Generalitat de Catalunya (Consolidated Research Groups 2014-SGR-476 and 2014-SGR-291). The Department of Chemical Engineering of the Universitat Autonoma de Barcelona (UAB) is a member of the Xarxa de Referencia en Biotecnologia de la Generalitat de Catalunya. M. Badia-Fabregat and D. Lucas acknowledge the predoctoral grants from UAB and from the Spanish Ministry of Education, Culture and Sports (AP-2010-4926), respectively. The authors also thank the Portuguese Foundation for Science and Technology (FCT) Strategic Project PEst-OE/EQB/LA0023/2013, Project FCOMP-01-0124-FEDER-027462 co-funded by Operational Competitiveness Programme, FEDER, and Project "BioEnv-Biotechnology and Bioengineering for a sustainable world," REF. NORTE-07-0124-FEDER-000048, co-funded by Programa Operacional Regional do Norte (ON.2 - O Novo Norte), QREN, FEDER