Sampling of explosive residues: the use of a gelatine-based medium for the recovery of ammonium nitrate

Forensic scientists must be able to recover traces of any original explosive materials not consumed in the detonation, in a careful controlled manner to aid a crime reconstruction. In current sampling techniques, the collection efficiency of post-blast residue is highly variable and often dependent on the swabbing materials and solvent systems used. To address these method limitations, this study presents a gelatine-based sampling medium and assesses its capabilities for the collection of ammonium nitrate. Common surfaces were spotted with a known concentration of ammonium nitrate, the unset gel applied, allowed to set, and then peeled from the surface. The gel was dissolved, and solid phase extraction employed to isolate the target explosive compound and remove the constituents of the gel. The eluate was concentrated and subsequently analysed and quantified. Overall, the gel formulation was able to collect ammonium nitrate from all of the test surfaces, with recoveries ranging from 0.1% to 61.7%. This study presents a gelatine-based formulation that has the potential to become a valuable asset in the forensic tool kit for the collection of explosive traces. A key attribute of the gel is that it offers an alternative recovery tool to conventional swabbing and solvent extraction methods

Pollen viability and germination in Jatropha ribifolia and Jatropha mollissima (Euphorbiaceae): Species with potential for biofuel production

The aim of this work is to assess pollen viability using the staining  technique and in vitro germination with different concentrations of sucrose in Jatropha ribifolia and Jatropha mollissima, contributing to the knowledge of the reproductive biology and subsidizing their conservation,  management and utilization. Pollen viability was measured by dye method. Acetocarmine, acetic orcein and cotton-blue stain were used. The culture medium for pollen germination was solidificated by the addition of 1% agar combined with 0 (control), 10, 20, 30 and 40% of sucrose. The data were submitted to analysis of variance at 5% probability. All dyes used in this experiment allowed easy differentiation between fertileand non fertile pollen. The rate of formation of pollen tubes was higher in medium with 10% of sucrose for both species because the trend is that the sucrose concentration increases the supply of carbon, changes the osmotic potential and inhibits the formation of pollen tube in vitro.Key words: Plant reproduction, male gametophyte, hybridization, germplasm

Three-dimensional culture of single embryonic stem-derived neural/stem progenitor cells in fibrin hydrogels: neuronal network formation and matrix remodelling

In an attempt to improve the efficacy of neural stem/progenitor cell (NSPC) based therapies, fibrin hydrogels are being explored to provide a favourable microenvironment for cell survival and differentiation following transplantation. In the present work, the ability of fibrin to support the survival, proliferation, and neuronal differentiation of NSPCs derived from embryonic stem (ES) cells under monolayer culture was explored. Single mouse ES-NSPCs were cultured within fibrin (fibrinogen concentration: 6 mg/ml) under neuronal differentiation conditions up to 14 days. The ES-NSPCs retained high cell viability and proliferated within small-sized spheroids. Neuronal differentiation was confirmed by an increase in the levels of ßIII-tubulin and NF200 over time. At day 14, cell-matrix constructs mainly comprised NSPCs and neurons (46.5% ßIII-tubulin + cells). Gamma-aminobutyric acid (GABA)ergic and dopaminergic/noradrenergic neurons were also observed, along with a network of synaptic proteins. The ES-NSPCs expressed matriptase and secreted MMP-2/9, with MMP-2 activity increasing along time. Fibronectin, laminin and collagen type IV deposition was also detected. Fibrin gels prepared with higher fibrinogen concentrations (8/10 mg/ml) were less permissive to neurite extension and neuronal differentiation, possibly owing to their smaller pore area and higher rigidity. Overall, it is shown that ES-NSPCs within fibrin are able to establish neuronal networks and to remodel fibrin through MMP secretion and extracellular matrix (ECM) deposition. This three-dimensional (3D) culture system was also shown to support cell viability, neuronal differentiation and ECM deposition of human ES-NSPCs. The settled 3D platform is expected to constitute a valuable tool to develop fibrin-based hydrogels for ES-NSPC delivery into the injured central nervous system.The authors would like to acknowledge Prof. Domingos Henrique (Instituto de Medicina Molecular, Lisbon) for providing the ES 46C cell line. This work was supported by FEDER funds through the Programa Operacional Factores de Competitividade – COMPETE (FCOMP‐01–0124‐FEDER‐021125) and by National funds FCT – Fundação para a Ciência e a Tecnologia (PTDC/SAU‐BMA/118869/2010). A.R.B. and M.J. Oliveira are supported by FCT (SFRH/BD/86200/2012; Investigator FCT)

Biomimetic synthetic self-assembled hydrogels for cell transplantation

The development of three-dimensional matrices capable of recapitulating the main features of native extracellular matrix and contribute for the establishment of a favorable microenvironment for cell behavior and fate is expected to circumvent some of the main limitations of cell-based therapies. In this context, self-assembly has emerged as a promising strategy to engineer cell-compatible hydrogels. A wide number of synthetically-derived biopolymers, such as proteins, peptides and DNA/RNA, with intrinsic ability to self-assemble into well-defined nanofibrous structures, are being explored. The resulting hydrogels, in addition to closely resembling the architecture of native cellular microenvironments, present a versatile and dynamic behavior that allows them to be designed to undergo sol-to-gel transition in response to exogenous stimulus. This review presents an overview on the state-of-the-art of the different strategies being explored for the development of injectable synthetic self-assembled hydrogels for cell transplantation and/or recruitment of endogenous cells, with an emphasis on their biological performance, both in vitro and in vivo. Systems based on peptides are the most widely explored and have already generated promising results in pre-clinical in vivo studies involving different repair/regenerative scenarios, including cartilage, bone, nerve and heart. On the other hand, systems based on DNA and hybrid hydrogels are now emerging for application in the biomedical field with high potential. Finally, the main challenges hampering the translation of these systems to the clinic and the issues that need to be addressed for these to progress from bench-to-bedside are discussed.The authors would like to acknowledge the FEDER funds through the Programa Operacional Factores de Competitividade – COMPETE and the Portuguese funds through FCT – Fundação para a Ciência e a Tecnologia (HMSPICT/0020/2010, PTDC/SAU-BMA/118869/2010 and PEst/SAU/LA0002/2013) that supported this work. D Barros is supported by FCT (PD/BD/105953/2014) and I.F. Amaral by QREN through program ON.2, in the framework of "Project on Biomedical Engineering for Regenerative Therapies and Cancer” (NORTE-07-0124-FEDER-000005)

Processo de letramento a partir das escritas dos alunos sobre aulas de matemática

Este trabalho traz um recorte da dissertação que teve como objetivo principal abordar indícios de letramento do professor constituído a partir das reflexões sobre a escrita dos alunos sobre aulas de matemática. A pesquisa foi realizada em parceria com um grupo de professores, de uma escola pública da rede municipal de Atibaia - SP, onde ocorreram as reuniões para análise da escrita dos professores e dos alunos sobre aulas de matemática. Nesse recorte, vamos trazer o que consideramos evento de letramento na qual os professores discutiam a escrita dos alunos, de acordo com o ano escolar, em duplas discutiam e socializavam a discussão no final de cada encontro. Esses eventos nos ajudaram a compreender a questão de investigação: “que aprendizagens a “ESCRITA” do professor sobre a escrita dos alunos possibilita no processo de ensinar e de aprender matemática na perspectiva do letramento?”. Assim, os resultados evidenciaram o quanto é importante e formativa a participação dos professores em sua própria formação, tornando-os protagonista do processo de ensinar e de aprender matemática