Quick and robust method for trace determination of MeHg in rice and rice products without derivatisation

Peer reviewed

Approximate ab initio calculations and the method of molecular fragments

A two stage approach to performing ab initio calculations on medium and large sized molecules is described. The first step is to perform SCF calculations on small molecules or molecular fragments using the OPIT Program. This employs a small basis set of spherical and p-type Gaussian functions. The Gaussian functions can be identified very closely with atomic cores, bond pairs, lone pairs, etc. The position and exponent of any of the Gaussian functions can be varied by OPIT to produce a small but fully optimised basis set. The second stage is the molecular fragments method. As an example of this, Gaussian exponents and distances are taken from an OPIT calculation on ethylene and used unchanged in a single SCF calculation on benzene. Approximate ab initio calculations of this type give much useful information and are often preferable to semi-empirical approaches, since the nature of the approximations involved is much better defined.

A deformation model of flexible, high area-to-mass ratio debris under perturbations and validation method

A new type of space debris was recently discovered by Schildknecht in near -geosynchronous orbit (GEO). These objects were later identified as exhibiting properties associated with High Area-to-Mass ratio (HAMR) objects. According to their brightness magnitudes (light curve), high rotation rates and composition properties (albedo, amount of specular and diffuse reflection, colour, etc), it is thought that these objects are multilayer insulation (MLI). Observations have shown that this debris type is very sensitive to environmental disturbances, particularly solar radiation pressure, due to the fact that their shapes are easily deformed leading to changes in the Area-to-Mass ratio (AMR) over time. This thesis proposes a simple effective flexible model of the thin, deformable membrane with two different methods. Firstly, this debris is modelled with Finite Element Analysis (FEA) by using Bernoulli-Euler theory called “Bernoulli model”. The Bernoulli model is constructed with beam elements consisting 2 nodes and each node has six degrees of freedom (DoF). The mass of membrane is distributed in beam elements. Secondly, the debris based on multibody dynamics theory call “Multibody model” is modelled as a series of lump masses, connected through flexible joints, representing the flexibility of the membrane itself. The mass of the membrane, albeit low, is taken into account with lump masses in the joints. The dynamic equations for the masses, including the constraints defined by the connecting rigid rod, are derived using fundamental Newtonian mechanics. The physical properties of both flexible models required by the models (membrane density, reflectivity, composition, etc.), are assumed to be those of multilayer insulation. Both flexible membrane models are then propagated together with classical orbital and attitude equations of motion near GEO region to predict the orbital evolution under the perturbations of solar radiation pressure, Earth’s gravity field, luni-solar gravitational fields and self-shadowing effect. These results are then compared to two rigid body models (cannonball and flat rigid plate). In this investigation, when comparing with a rigid model, the evolutions of orbital elements of the flexible models indicate the difference of inclination and secular eccentricity evolutions, rapid irregular attitude motion and unstable cross-section area due to a deformation over time. Then, the Monte Carlo simulations by varying initial attitude dynamics and deformed angle are investigated and compared with rigid models over 100 days. As the results of the simulations, the different initial conditions provide unique orbital motions, which is significantly different in term of orbital motions of both rigid models. Furthermore, this thesis presents a methodology to determine the material dynamic properties of thin membranes and validates the deformation of the multibody model with real MLI materials. Experiments are performed in a high vacuum chamber (10-4 mbar) replicating space environment. A thin membrane is hinged at one end but free at the other. The free motion experiment, the first experiment, is a free vibration test to determine the damping coefficient and natural frequency of the thin membrane. In this test, the membrane is allowed to fall freely in the chamber with the motion tracked and captured through high velocity video frames. A Kalman filter technique is implemented in the tracking algorithm to reduce noise and increase the tracking accuracy of the oscillating motion. The forced motion experiment, the last test, is performed to determine the deformation characteristics of the object. A high power spotlight (500-2000W) is used to illuminate the MLI and the displacements are measured by means of a high resolution laser sensor. Finite Element Analysis (FEA) and multibody dynamics of the experimental setups are used for the validation of the flexible model by comparing with the experimental results of displacements and natural frequencies.

Congenital thoracic vertebral malformations in brachycephalic “screw-tailed” dog breeds: Validation of a human classification scheme and a method of Cobb angle measurement in the assessment of vertebral column deformity

Congenital vertebral malformations are common in brachycephalic “screw-tailed” dog breeds such as French bulldogs, English bulldogs, Boston terriers, and Pugs. Those vertebral malformations disrupt the normal vertebral column anatomy and biomechanics, potentially leading to deformity of the vertebral column and subsequent neurological dysfunction. The initial aim of this work was to study and determine whether the congenital vertebral malformations identified in those breeds could be translated in a radiographic classification scheme used in humans to give an improved classification, with clear and well-defined terminology, with the expectation that this would facilitate future study and clinical management in the veterinary field. Therefore, two observers who were blinded to the neurologic status of the dogs classified each vertebral malformation based on the human classification scheme of McMaster and were able to translate them successfully into a new classification scheme for veterinary use. The following aim was to assess the nature and the impact of vertebral column deformity engendered by those congenital vertebral malformations in the target breeds. As no gold standard exists in veterinary medicine for the calculation of the degree of deformity, it was elected to adapt the human equivalent, termed the Cobb angle, as a potential standard reference tool for use in veterinary practice. For the validation of the Cobb angle measurement method, a computerised semi-automatic technique was used and assessed by multiple independent observers. They observed not only that Kyphosis was the most common vertebral column deformity but also that patients with such deformity were found to be more likely to suffer from neurological deficits, more especially if their Cobb angle was above 35 degrees.

Exploring New Material and Analytical Method for Characterization and Conservation of Artifacts

In this dissertation, we focus on developing new green bio-based gel systems and evaluating both the cleaning efficiency and the release of residues on the treated surface, different micro or no destructive techniques, such as optical microscopy, TGA, FTIR spectroscopy, HS-SPME and micro-Spatially Offset Raman spectroscopy (micro-SORS) were tested, proposing advanced analytical protocols. In the first part, a ternary PHB-DMC/BD gel system composed by biodiesel, dimethyl carbonate and poly-3 hydroxybutyrate was developed for cleaning of wax-based coatings applied on indoor bronze. The evaluation of the cleaning efficacy of the gel was carried out on a standard bronze sample which covered a layer of beeswax by restores of Opificio delle Pietre Dure in Florence, and a real case precious indoor bronze sculpture Pulpito della Passione attributed to Donatello. Results obtained by FTIR analysis showed an efficient removal of the wax coating. In the second part, two new kinds of combined gels based on electrospun tissues (PVA and nylon) and PHB-GVL gel were developed for removal of dammar varnish from painting. The electrospun tissue combined gels exhibited good mechanical property, and showed good efficient in cleaning over normal gel. In the third part, green deep eutectic solvent which consists urea and choline chloride was proposed to produce the rigid gel with agar for the removal of proteinaceous coating from oil painting. Rabbit glue and whole egg decorated oil painting mock-ups were selected for evaluating its cleaning efficiency, results obtained by ATR analysis showed the DES-agar gel has good cleaning performance. Furthermore, we proposed micro-SORS as a valuable alternative non-destructive method to explore the DES diffusion on painting mock-up. As a result, the micro-SORS was successful applied for monitoring the liquid diffusion behavior in painting sub-layer, providing a great and useful instrument for noninvasive residues detection in the conservation field.

Remistura de vídeo: um estudo exploratório de diferentes estilos

Dissertação apresentada à Escola Superior de Comunicação Social como parte dos requisitos para obtenção de grau de mestre em Audiovisual e Multimédia.

Cointegrase, a naturally occurring, truncated form of IS21 transposase, catalyzes replicon fusion rather than simple insertion of IS21.

The bacterial insertion sequence IS21 contains two genes, istA and istB, which are organized as an operon. IS21 spontaneously forms tandem repeats designated (IS21)2. Plasmids carrying (IS21)2 react efficiently with other replicons, producing cointegrates via a cut-and-paste mechanism. Here we show that transposition of a single IS21 element (simple insertion) and cointegrate formation involving (IS21)2 result from two distinct non-replicative pathways, which are essentially due to two differentiated IstA proteins, transposase and cointegrase. In Escherichia coli, transposase was characterized as the full-length, 46 kDa product of the istA gene, whereas the 45 kDa cointegrase was expressed, in-frame, from a natural internal translation start of istA. The istB gene, which could be experimentally disconnected from istA, provided a helper protein that strongly stimulated the transposase and cointegrase-driven reactions. Site-directed mutagenesis was used to express either cointegrase or transposase from the istA gene. Cointegrase promoted replicon fusion at high frequencies by acting on IS21 ends which were linked by 2, 3, or 4 bp junction sequences in (IS21)2. By contrast, cointegrase poorly catalyzed simple insertion of IS21 elements. Transposase had intermediate, uniform activity in both pathways. The ability of transposase to synapse two widely spaced IS21 ends may reside in the eight N-terminal amino acid residues which are absent from cointegrase. Given the 2 or 3 bp spacing in naturally occurring IS21 tandems and the specialization of cointegrase, the fulminant spread of IS21 via cointegration can now be understood.

Sämpläys - leikkausta ja liimausta vai luovaa tulkintaa? : the Avalanches ja sämpläyksen varaan rakentuva tekijyys

[Abstract: Sampling - cut and paste or innovative creation? : the Avalanches and its sampling-based authorship]

Proposição dos modelos de expansão genômica dos elementos de transposição 412 e Bari no genoma de espécies do grupo melanogaster e em populações naturais de Drosophila melanogaster e de D. simulans

Pós-graduação em Genética - IBILCE

Regulated transposition of a fish transposon in the mouse germ line

Tc1/mariner elements are able to transpose in species other than the host from which they were isolated. As potential vectors for insertional mutagenesis and transgenesis of the mouse, these cut-and-paste transposons were tested for their ability to transpose in the mouse germ line. First, the levels of activity of several Tc1/mariner elements in mammalian cells were compared; the reconstructed fish transposon Sleeping Beauty (SB) was found to be an order of magnitude more efficient than the other tested transposons. SB then was introduced into the mouse germ line as a two-component system: one transgene for the expression of the transposase in the male germ line and a second transgene carrying a modified transposon. In 20% of the progeny of double transgenic male mice the transposon had jumped from the original chromosomal position into another locus. Analysis of the integration sites shows that these jumps indeed occurred through the action of SB transposase, and that SB has a strong preference for intrachromosomal transposition. Analysis of the excision sites suggests that double-strand breaks in haploid spermatids are repaired via nonhomologous end joining. The SB system may be a powerful tool for transposon mutagenesis of the mouse germ line.

Rolling-circle transposons in eukaryotes

All eukaryotic DNA transposons reported so far belong to a single category of elements transposed by the so-called “cut-and-paste” mechanism. Here, we report a previously unknown category of eukaryotic DNA transposons, Helitron, which transpose by rolling-circle replication. Autonomous Helitrons encode a 5′-to-3′ DNA helicase and nuclease/ligase similar to those encoded by known rolling-circle replicons. Helitron-like transposons have conservative 5′-TC and CTRR-3′ termini and do not have terminal inverted repeats. They contain 16- to 20-bp hairpins separated by 10–12 nucleotides from the 3′-end and transpose precisely between the 5′-A and T-3′, with no modifications of the AT target sites. Together with their multiple diverged nonautonomous descendants, Helitrons constitute ≈2% of both the Arabidopsis thaliana and Caenorhabditis elegans genomes and also colonize the Oriza sativa genome. Sequence conservation suggests that Helitrons continue to be transposed.

Bending of stochastic Kirchhoff plates on Winkler foundations via the Galerkin method and the Askey-Wiener scheme

In this paper, the method of Galerkin and the Askey-Wiener scheme are used to obtain approximate solutions to the stochastic displacement response of Kirchhoff plates with uncertain parameters. Theoretical and numerical results are presented. The Lax-Milgram lemma is used to express the conditions for existence and uniqueness of the solution. Uncertainties in plate and foundation stiffness are modeled by respecting these conditions, hence using Legendre polynomials indexed in uniform random variables. The space of approximate solutions is built using results of density between the space of continuous functions and Sobolev spaces. Approximate Galerkin solutions are compared with results of Monte Carlo simulation, in terms of first and second order moments and in terms of histograms of the displacement response. Numerical results for two example problems show very fast convergence to the exact solution, at excellent accuracies. The Askey-Wiener Galerkin scheme developed herein is able to reproduce the histogram of the displacement response. The scheme is shown to be a theoretically sound and efficient method for the solution of stochastic problems in engineering. (C) 2009 Elsevier Ltd. All rights reserved.

Differences in mouse strain influence leukocyte and immunoglobulin phenotype response to Porphyromonas gingivalis

This study examined the nature of the infiltrating cells in Porphyromonas gingivalis-induced lesions and immunoglobulins in the serum samples of BALB/c (H-2(d)), C57BL6 (H-2(b)), DBA/2J (H-2(d)) and CBA/CaH (H-2(k)) mice. Mice were immunized intraperitoneally with P. gingivalis outer membrane antigens or sham-immunized with phosphate-buffered saline followed by subcutaneous challenge with live organisms 1 week after the final immunization. The resulting skin abscesses were excised 7 days later, cryostat sections cut and an immunoperoxidase method used to detect the presence of CD4(+) and CD8(+) T-cell subsets, CD14(+) macrophages and CD19(+) B cells. Peroxidase positive neutrophils and IgG1- and IgG2a-producing plasma cells were also identified. Anti P. gingivalis IgG1 and IgG2a subclass antibodies were determined in serum obtained by cardiac puncture. Very few CD8(+) T cells and CD19(+) B cells were found in any of the lesions. The percentages of CD4(+) cells, CD14(+) cells and neutrophils were similar in lesions of immunized BALB/c and C57BL6 mice, with a trend towards a higher percentage of CD14(+) cells in sham-immunized mice. The percentage of CD14(+) cells was higher than that of CD4(+) cells in immunized compared with sham-immunized DBA/2J mice. The percentages of CD4(+) and CD14(+) cells predominated in immunized CBA/CaH mice and CD4(+) cells in sham-immunized CBA/CaH mice. The percentage of neutrophils in immunized CBA/CaH mice was significantly lower than that of CD14(+) cells and CD4(+) cells in sham-immunized mice. IgG1(+) plasma cells were more dominant than IgG2a(+) cells in immunized BALB/c, C57BL6 and DBA/2J mice, whereas IgG2a(+) plasma cells were more obvious in sham-immunized mice. IgG2a(+) plasma cells were predominant in immunized and sham-immunized CBA/CaH mice. In the serum, specific anti-P. gingivalis IgG2a antibody levels (Th1 response) were higher than IgG1 levels (Th2 response) in sham-immunized CBA/CaH and DBA/2J mice. In immunized BALB/c mice, IgG2a levels were lower than IgG1 levels, while IgG2a levels were higher in immunized C57BL6 mice. In conclusion, this study has shown differences in the proportion of infiltrating leukocytes and in the subclasses of immunoglobulin produced locally and systemically in response to P. gingivalis in different strains of mice, suggesting a degree of genetic control over the response to P. gingivalis.

A single method to stain Malassezia furfur and Corynebacterium minutissimum in scales

A single and practical method to slain Malassezia furfur and Corynebacterium minutissimum in lesions' scales is described. The scales are collected by pressing small pieces of scotch tape (about 4 cm lenght and 2 cm width) onto the lesions and following withdrawl the furfuraceous scales will remain on the glue side. These pieces are then immersed for some minutes in lactophenol-cotton blue stain. Following absorption of the stain the scales are washed in current water to remove the excess of blue stain, dried with filter paper, dehydrated via passage in two bottles containing absolute alcohol and then placed in xylene in a centrifugation tube. The xylene dissolves the scotch tape glue and the scales fall free in the tube. After centrifugation and decantation the scales concentrated on the bottom of the tube are collected with a platinum-loop, placed in Canada balsam on a microscopy slide and closed with a cover slip. The preparations are then ready to be submitted to microscopic examination. Other stains may also be used instead of lactophenol-cotton blue. This method is simple, easily performed, and offers good conditions to study these fungi as well as being useful for the diagnosis of the diseases that they cause.