Chaotic mixing using source-sink microfluidic flows in a PDMS chip

We present an active fixed-volume mixer based on the creation of multiple source-sink microfluidic flows in a polydimethylsiloxane (PDMS) chip without the need of external or internal pumps. To do so, four different pressure-controlled actuation chambers are arranged on top of the 5μl volume of the mixing chamber. After the mixing volume is sealed/fixed by microfluidic valves made using ‘microplumbing technology', a virtual source-sink pair is created by pressurizing one of the membranes and, at the same time, releasing the pressure of a neighboring one. The pressurized air deforms the thin membrane between the mixing and control chambers and creates microfluidic flows from the squeezed region (source) to the released region (sink) where the PDMS membrane is turned into the initial state. Several schemes of operation of virtual source-sink pairs are studied. In the optimized protocol, mixing is realized in just a sub-second time interval, thanks to the implementation of chaotic advectio

O ensino público e a formação dos professores no Brasil: na direção de novas reformas curriculares

Este artigo examina a história da formação de professores no Brasil e aponta que o atual estado do processo de formação de docentes no país é produzido por meio de políticas públicas específicas. A baixa qualidade da educação pública expressa a falta de apoio aos profissionais de educação. Este artigo apresenta também um novo programa de formação de quadros de professores, na Suíça, baseado na estreita relação com as escolas locais

O ensino público e a formação dos professores no Brasil: na direção de novas reformas curriculares

Este artigo examina a história da formação de professores no Brasil e aponta que o atual estado do processo de formação de docentes no país é produzido por meio de políticas públicas específicas. A baixa qualidade da educação pública expressa a falta de apoio aos profissionais de educação. Este artigo apresenta também um novo programa de formação de quadros de professores, na Suíça, baseado na estreita relação com as escolas locais

Barium manganese(II) selenostannate(IV), BaMnSnSe4

The title compound, BaMnSnSe4, was obtained by reaction of the elements at 1123 K in an evacuated silica tube. It adopts the BaCdSnS4 structure type, which is a variant of the SrIn2Se4 structure type. Its structure consists of distorted edge-sharing tetra­hedra, alternating with Mn and Sn atoms as central atom. These [MnSnSe6] units display corner sharing, forming stacked infinite layers in the ac plane. The three different Ba2+ atoms are located between the [MnSnSe6] layers, two on twofold rotation axes, and exhibit distorted square-antiprismatic coordinations

Aqua­bis(3,5-dimethyl-1H-pyrazole-κN)(oxalato-κ2 O,O′)copper(II)

In the title compound, [Cu(C2O4)(C5H8N2)2(H2O)], the CuII atom is coordinated in a slightly distorted square-pyramidal geometry by two N atoms belonging to the two 3,5-dimethyl-1H-pyrazole ligands, two O atoms of the oxalate anion providing an O,O′-chelating coordination mode, and an O atom of the water mol­ecule occupying the apical position. The crystal packing shows a well defined layer structure. Intra-layer connections are realised through a system of hydrogen bonds while the nature of the inter-layer inter­actions is completely hydro­phobic, including no hydrogen-bonding inter­actions

The Odonata fauna of the Seybouse river catchment in Algeria as part of the Maghrebian biodiversity

An odonatological survey of the wadi Seybouse watershed, Northeastern Algeria, was carried out over a period of two years. Thirty five species were recorded in this previously uncharted region, including Calopteryx exul and Trithemis kirbyi. The former species, a Maghrebian endemic, has been rediscovered in Algeria after more than a century of apparent absence and the species, classified as “Endangered” in the IUCN Mediterranean Red List, is represented in Algeria by only the Seybouse population. An efficient conservation plan is needed to prevent the extinction of this emblematic species. T. kirbyi, a desert species, has considerably extended its range northward. Anthropogenic impacts were noted for the majority of sampled stations and this pressure does not bode well for the conservation of the biodiversity of wadi Seybouse. The distribution and status of each recorded species were also discussedUne étude odonatologique a été réalisée durant deux années consécutives dans le bassin-versant de la Seybouse, situé dans le nord-est algérien et pratiquement inexploré auparavant. Trente cinq espèces ont été enregistrées, dont Caloptervx exul et Trithemis kirbyi. La première, endémique du Maghreb, n'avait plus été observée en Algérie depuis plus d'un siècle et la population de l'oued Seybouse représente la seule actuellement connue en Algérie. Une protection efficace de ce bassin hydrographique est donc nécessaire afin de conserver cette espèce emblématique, en forte régression dans l'ensemble du Maghreb et considérée « en danger » par l'UICN. T kirbyi, espèce saharienne, a considérablement étendu son aire de répartition vers le nord. Une pression anthropique intense a été notée dans la majorité des stations échantillonnées. La répartition géographique et le statut de chaque espèce notée sont discutés

An autosomal recessive leucoencephalopathy with ischemic stroke, dysmorphic syndrome and retinitis pigmentosa maps to chromosome 17q24.2-25.3

Background Single-gene disorders related to ischemic stroke seem to be an important cause of stroke in young patients without known risk factors. To identify new genes responsible of such diseases, we studied a consanguineous Moroccan family with three affected individuals displaying hereditary leucoencephalopathy with ischemic stroke, dysmorphic syndrome and retinitis pigmentosa that appears to segregate in autosomal recessive pattern. Methods All family members underwent neurological and radiological examinations. A genome wide search was conducted in this family using the ABI PRISM linkage mapping set version 2.5 from Applied Biosystems. Six candidate genes within the region linked to the disease were screened for mutations by direct sequencing. Results Evidence of linkage was obtained on chromosome 17q24.2-25.3. Analysis of recombination events and LOD score calculation suggests linkage of the responsible gene in a genetic interval of 11 Mb located between D17S789 and D17S1806 with a maximal multipoint LOD score of 2.90. Sequencing of seven candidate genes in this locus, ATP5H, FDXR, SLC25A19, MCT8, CYGB, KCNJ16 and GRIN2C, identified three missense mutations in the FDXR gene which were also found in a homozygous state in three healthy controls, suggesting that these variants are not disease-causing mutations in the family. Conclusion A novel locus for leucoencephalopathy with ischemic stroke, dysmorphic syndrome and retinitis pigmentosa has been mapped to chromosome 17q24.2-25.3 in a consanguineous Moroccan family

Optical Microscopy in the Nano-World

Scanning near-field optical microscopy (SNOM) is an optical microscopy whose resolution is not bound to the diffraction limit. It provides chemical information based upon spectral, polarization and/or fluorescence contrast images. Details as small as 20 nm can be recognized. Photophysical and photochemical effects can be studied with SNOM on a similar scale. This article reviews a good deal of the experimental and theoretical work on SNOM in Switzerland