On the sensitivity of generic porous optical sensors

A porous material was considered as a platform for optical sensing. It was envisaged that the porous material was infiltrated by a fluid which contains an agent to be sensed. Changes in the optical properties of the infiltrated porous material provide the basis for detection of the agent to be sensed. Using a homogenization approach based on the Bruggeman formalism, wherein the infiltrated porous material was regarded as a homogenized composite material, the sensitivity of such a sensor was investigated. For the case of an isotropic dielectric porous material of relative permittivity $\epsilon^a$ and an isotropic dielectric fluid of relative permittivity $\epsilon^b$, it was found that the sensitivity was maximized when there was a large contrast between $\epsilon^a$ and $\epsilon^b$; the maximum sensitivity was achieved at mid-range values of porosity. Especially high sensitivities may be achieved for $\epsilon^b$ close to unity when $\epsilon^a >> 1$, for example. Furthermore, higher sensitivities may be achieved by incorporating pores which have elongated spheroidal shapes

Rapid antibody selection using surface plasmon resonance for high-speed and sensitive hazelnut lateral flow prototypes

Lateral Flow Immunoassays (LFIAs) allow for rapid, low-cost, screening of many biomolecules such as food allergens. Despite being classified as rapid tests, many LFIAs take 10–20 min to complete. For a really high-speed LFIA, it is necessary to assess antibody association kinetics. By using a label-free optical technique such as Surface Plasmon Resonance (SPR), it is possible to screen crude monoclonal antibody (mAb) preparations for their association rates against a target. Herein, we describe an SPR-based method for screening and selecting crude anti-hazelnut antibodies based on their relative association rates, cross reactivity and sandwich pairing capabilities, for subsequent application in a rapid ligand binding assay. Thanks to the SPR selection process, only the fast mAb (F-50-6B12) and the slow (S-50-5H9) mAb needed purification for labelling with carbon nanoparticles to exploit high-speed LFIA prototypes. The kinetics observed in SPR were reflected in LFIA, with the test line appearing within 30 s, almost two times faster when F-50-6B12 was used, compared with S-50-5H9. Additionally, the LFIAs have demonstrated their future applicability to real life samples by detecting hazelnut in the sub-ppm range in a cookie matrix. Finally, these LFIAs not only provide a qualitative result when read visually, but also generate semi-quantitative data when exploiting freely downloadable smartphone apps.</p

Consumer-friendly food allergen detection : moving towards smartphone-based immunoassays

In this critical review, we provide a comprehensive overview of immunochemical food allergen assays and detectors in the context of their user-friendliness, through their connection to smartphones. Smartphone-based analysis is centered around citizen science, putting analysis into the hands of the consumer. Food allergies represent a significant worldwide health concern and consumers should be able to analyze their foods, whenever and wherever they are, for allergen presence. Owing to the need for a scientific background, traditional laboratory-based detection methods are generally unsuitable for the consumer. Therefore, it is important to develop simple, safe, and rapid assays that can be linked with smartphones as detectors to improve user accessibility. Smartphones make excellent detection systems because of their cameras, embedded flash functions, portability, connectivity, and affordability. Therefore, this review has summarized traditional laboratory-based methods for food allergen detection such as enzyme-linked-immunosorbent assay, flow cytometry, and surface plasmon resonance, and the potential to modernize these methods by interfacing them with a smartphone readout system, based on the aforementioned smartphone characteristics. This is the first review focusing on smartphone-based food-allergen detection methods designed with the intention of being consumer-friendly. [Figure not available: see fulltext.

Cryogenics for CERN experiments: past, present and future

Use of cryogenics at CERN was originated (in the 1960s) by bubble chambers and the associated s.c. solenoids. Complex cryoplants were installed to provide cooling at LH2 and LHe temperatures. Continuity (in the 1970s) in He cryogenics for experiments was provided by spectrometer magnets for fixed target physics of the SPS accelerator. More recently (in the 1980s), large "particle-transparent" s.c. solenoids for collider experiments (LEP) have been built demanding new cryoplants. The LHC experiments (in the 2000s) will continue the tradition with s.c. dipoles (ALICE and LHCb), solenoids (CMS, ATLAS) and toroids (ATLAS) of unusual size. Cryogenics for experiments using noble liquids follows the same trend since the development (in the 1970s) of the first shower LAr detectors. A LKr calorimeter (about 10 m3) will be operated in 1996 and the ATLAS experiment foresees a set of three huge LAr calorimeters (almost 90 m3 total volume of liquid) to be installed underground

The Biological and Ethical Basis of the Use of Human Embryonic Stem Cells for In Vitro Test Systems or Cell Therapy

Human embryonic stem cells (hESC) are now routinely cultured in many laboratories, and differentiation protocols are available to generate a large variety of cell types. In an ongoing ethical debate opinions of different groups are based on varying sets of religious, historical, cultural and scientific arguments as well as on widely differing levels of general information. We here give an overview of the biological background for non-specialists, and address all issues of the current stem cell debate that are of concern in different cultures and states. Thirty-five chapters address embryo definition, potential killing and the beginning of human life, in addition to matters of human dignity, patenting, commercialisation, and potential alternatives for the future, such as induced pluripotent (reprogrammed) stem cells. All arguments are compiled in a synopsis, and compromise solutions, e.g. for the definition of the beginning of personhood and for assigning dignity to embryos, are suggested. Until recently, the major application of hESC was thought to be transplantation of cells derived from hESC for therapeutic use. We discuss here that the most likely immediate uses will rather be in vitro test systems and disease models. Major and minor pharmaceutical companies have entered this field, and the European Union is sponsoring academic research into hESC-based innovative test systems. This development is supported by new testing strategies in Europe and the USA focussing on human cell-based in vitro systems for safety evaluations, and shifting the focus of toxicology away from classical animal experiments towards a more mechanistic understanding.JRC.I.3-In-vitro method

Caracterização morfométrica da península Fildes, Ilha Rei George, Antártica Marítima

Na região da Antártica Marítima, apesar das severas condições climáticas, há vegetação, hidrografia e feições geomorfológicas que configuram os ecossistemas locais. Este trabalho tem como objetivo quantificar e analisar os parâmetros morfométricos da Península Fildes, localizada na Ilha Rei George, Antártica Marítima. O modelo digital do terreno (MDT) foi gerado a partir dos dados altimétricos da carta topográfica da Península Fildes e, a partir do MDT, foram gerados os produtos de hipsometria, declividade, orientação das vertentes e forma do terreno. A partir desses produtos foi possível analisar a morfometria da Península Fildes e, posterior- mente, quantificar a relação entre os produtos morfométricos e a geomorfologia local. Os resultados obtidos apontam que a altimetria média da Península Fildes é de 58,73 m, com predominância de relevo ondulado e suave ondulado. As vertentes orientadas para oeste possuem a maior representatividade, e não houve uma classe de forma do terreno com área destacadamente superior às outras. Os resultados desse estudo demons- tram que os produtos morfométricos podem ser utilizados para fins de análise das variáveis que compõem o relevo dos ambientes da Antártica Marítima. Esse estudo contribui para ampliar as informações de ambientes antárticos obtidos com escalas detalhadas

Geoambientes da Península Potter, Ilha Rei George, Antártica Marítima

The scientific community has great attention in the region of the Antarctic Maritime because of the climate changes detected since 1950. Mapping studies of Antarctic environments on detailed scales are limited, mainly due to the limitations of financial resources and logistics. The information generated by mappings makes it possible to detect environmental variations and contribute to the management of land use and occupation. The aim of this work was to identify and to map the geoenvironments of the Potter Peninsula, King George Island, Maritime Antarctica. For that, multi-criteria based analysis of geomorphology, landforms, vegetation and susceptibility to wind action were used to cluster their environmentalcharacteristics. Seven geoenvironments were identified and mapped: Marine terraces, Proglacial area with glaciofluvialaction, Marine terraces with anthropic influence, Marine terraces with vegetation colonization, Proglacial area with paraglacial action, Periglacial area and Glacier area. The ice-free area of the Peninsula has 668 ha and comprises six geoenvironments, with a predominance of terrains with convergent and concave forms and little or inexistent susceptibility to wind action. The seventh geoenvironment is located on the Polar Club glacier. In general, the geoenvironments of the marine terraces have greater fauna and flora biodiversity, while those in the inner part of the peninsula showed predominance of old and young moraines, exposed rocks and lakes.Com as mudanças climáticas na Antártica Marítima detectadas a partir de 1950, essa região tem apresentado grande interesse científico. Estudos de mapeamento dos ambientes antárticos em escalas detalhadas são limitados, principalmente devido às restrições orçamentárias e de logística. As informações geradas por mapeamentos são fundamentais para detectar variações ambientais e auxiliam na gestão do uso e ocupação da superfície terrestre.O objetivo deste trabalho foi identificar e mapear os geoambientes da Península Potter, Ilha Rei George, Antártica Marítima. Para isso, foram utilizadas análises multicritério com base em dados geomorfológicos, modelo de curvatura das vertentes, cobertura de vegetação e suscetibilidade à ação eólica, o que possibilitou a elaboração do zoneamento de suasprincipais características ambientais. Foram identificadas sete unidades geoambientais: Terraços marinhos, Área proglacial com atividade glaciofluvial, Terraços marinhos com ação antrópica, Terraços marinhos com cobertura de vegetação, Áreaproglacial com intensa atividade paraglacial, Áreaperiglacial e Área glacial. A área livre de gelo da Península tem 668 ha e engloba seis geoambientes, com predomínio de relevos com formas convergentes e côncavas e vertentes com pouca ou nenhuma suscetibilidade à ação eólica. O sétimo geoambiente está localizado na geleira Polar Club. Os geoambientesdos terraços marinhos exibem maior biodiversidade de fauna e flora antártica, enquanto aqueles da porção interna da exibem predomínio de morainas, rochas expostas e lagos decorrentes da ablação da neve e gelo da superfície e da geleira Polar Club

Metabolism and hydrophilicity of the polarised 'Janus face' all-cis tetrafluorocyclohexyl ring, a candidate motif for drug discovery

This work was supported by the Initial Training Network, FLUOR21, funded by the FP7 Marie Curie Actions of the European Commission (FP7-PEOPLE-2013-ITN-607787). JM is supported by a University Research Fellowship from the Royal Society. The research leading to these results has received funding from the European Research Council under the EU 7th Framework Programme (FP7/2007-2013)/ERC No 336289.The metabolism and polarity of the all-cis tetra-fluorocyclohexane motif is explored in the context of its potential as a motif for inclusion in drug discovery programmes. Biotransformations of phenyl all-cis tetra-, tri- and di- fluoro cyclohexanes with the human metabolism model organism Cunninghamella elegans illustrates various hydroxylated products, but limited to benzylic hydroxylation for the phenyl all-cis tetrafluorocyclohexyl ring system. Evaluation of the lipophilicities (Log P) indicate a significant and progressive increase in polarity with increasing fluorination on the cyclohexane ring system. Molecular dynamics simulations indicate that water associates much more closely with the hydrogen face of these Janus face cyclohexyl rings than the fluorine face owing to enhanced hydrogen bonding interactions with the polarised hydrogens and water.Publisher PDFPeer reviewe

Cleavage of a model DNA replication fork by a Type I restriction endonuclease

Cleavage of a DNA replication fork leads to fork restoration by recombination repair. In prokaryote cells carrying restriction–modification systems, fork passage reduces genome methylation by the modification enzyme and exposes the chromosome to attack by the restriction enzyme. Various observations have suggested a relationship between the fork and Type I restriction enzymes, which cleave DNA at a distance from a recognition sequence. Here, we demonstrate that a Type I restriction enzyme preparation cleaves a model replication fork at its branch. The enzyme probably tracks along the DNA from an unmethylated recognition site on the daughter DNA and cuts the fork upon encountering the branch point. Our finding suggests that these restriction–modification systems contribute to genome maintenance through cell death and indicates that DNA replication fork cleavage represents a critical point in genome maintenance to choose between the restoration pathway and the destruction pathway