2,757 research outputs found

    Per la corretta attribuzione del "Romanzo delle donne contemporanee in Italia" (1863)

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    The use of free energy simulation techniques in the study of protein stability is critically evaluated. Results from two simulations of the thermostability mutation Asn218 to Ser218 in Subtilisin are presented. It is shown that components of the free energy change can be highly sensitive to the computational details of the simulation leading to the conclusion that free energy calculations cannot currently be used to reliably predict protein stability. The different factors that undermine the reliability are discussed

    Counterflow dielectrophoresis for trypanosome enrichment and detection in blood

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    Human African trypanosomiasis or sleeping sickness is a deadly disease endemic in sub-Saharan Africa, caused by single-celled protozoan parasites. Although it has been targeted for elimination by 2020, this will only be realized if diagnosis can be improved to enable identification and treatment of afflicted patients. Existing techniques of detection are restricted by their limited field-applicability, sensitivity and capacity for automation. Microfluidic-based technologies offer the potential for highly sensitive automated devices that could achieve detection at the lowest levels of parasitemia and consequently help in the elimination programme. In this work we implement an electrokinetic technique for the separation of trypanosomes from both mouse and human blood. This technique utilises differences in polarisability between the blood cells and trypanosomes to achieve separation through opposed bi-directional movement (cell counterflow). We combine this enrichment technique with an automated image analysis detection algorithm, negating the need for a human operator

    Effects of serum proteins on corrosion behavior of ISO 5832–9 alloy modified by titania coatings

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    Stainless steel ISO 5832–9 type is often used to perform implants which operate in protein-containing physiological environments. The interaction between proteins and surface of the implant may affect its corrosive properties. The aim of this work was to study the effect of selected serum proteins (albumin and γ-globulins) on the corrosion of ISO 5832–9 alloy (trade name M30NW) which surface was modified by titania coatings. These coatings were obtained by sol– gel method and heated at temperatures of 400 and 800 °C. To evaluate the effect of the proteins, the corrosion tests were performed with and without the addition of proteins with concentration of 1 g L−1 to the physiological saline solution (0.9 % NaCl, pH 7.4) at 37 °C. The tests were carried out within 7 days. The following electrochemical methods were used: open circuit potential, linear polarization resistance, and electrochemical impedance spectroscopy. In addition, surface analysis by optical microscopy and X-ray photoelectron spectroscopy (XPS) method was done at the end of weekly corrosion tests. The results of corrosion tests showed that M30NW alloy both uncoated and modified with titania coatings exhibits a very good corrosion resistance during weekly exposition to corrosion medium. The best corrosion resistance in 0.9 % NaCl solution is shown by alloy samples modified by titania coating annealed at 400 °C. The serumproteins have no significant effect onto corrosion of investigated biomedical steel. The XPS results confirmed the presence of proteins on the alloy surface after 7 days of immersion in proteincontaining solutions.The investigations were supported by the National Science Centre project No. N N507 501339. The authors gratefully acknowledge Dr. Janusz Sobczak and Dr. hab. Wojciech Lisowski from Institute of Physical Chemistry of PAS for XPS surface analyses

    Anomalous codeposition of cobalt and ruthenium from chloride-sulfate baths

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    Codeposition of Ru and Co was studied at room temperature and at 50oC with various Ru3+ and Co2+ concentrations in the electrolyte. The codeposition of Co and Ru proved to be anomalous since no pure Ru could be obtained in the presence of Co2+ in the electrolyte, but a significant Co incorporation into the deposit was detected at potentials where the deposition of pure Co was not possible. The composition of the deposits varied monotonously with the change of the concentration ratio of Co2+ and Ru3+. The deposition of Ru was much hindered and the current efficiency was a few percent only when the molar fraction of Co in the deposit was low. Continuous deposits could be obtained only when the molar fraction of Co in the deposit was at least 40 at.%. The deposit morphology was related to the molar fraction of Co in the deposit. The X-ray diffractograms are in conformity with a hexagonal close-packed alloy and indicate the formation of nanocrystalline deposits. Two-pulse plating did not lead to a multilayer but to a Co-rich alloy. Magnetoresistance of the samples decreased with increasing Ru content

    Diffraction problems for quasilinear parabolic systems with boundary intersecting interfaces

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    Stability of Unilateral Posterior Crossbite Correction in the Mixed Dentition - an RCT-study with 3-year Follow-Up. Aim: To compare and evaluate long-term stability of crossbite correction with Quad Helix or expansion plate in the mixed dentition. Methods: In this RCT-study 35 patients with unilateral posterior crossbite were randomized to be treated with either Quad Helix or expansion plate. The inclusion criteria were: mixed dentition, unilateral posterior crossbite, no sucking habits or previous orthodontic treatment. Stability was evaluated after 3 years by study cast measurements. Twenty subjects with normal occlusion were included as controls. Success rate, maxillary and mandibular transverse dimensions, overjet, overbite and arch length were registered. Results: Stability was equal for the two treatment methods. Small, albeit significant, differences between the groups were assessed with reference to transverse dimensions. No significant difference was seen for overjet and overbite. The treated patients never reached the same transversal width as the normal control group. Conclusions: The long-term stability of posterior crossbite correction with Quad helix and expansion plate was equal. The maxillary width was greater in the control group than the treated groups

    Mimetic-enzyme fluorescence immunoassay using a thermal phase separating polymer

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    Poly-N-isopropylacrylamide (PNIP), a water-soluble, thermally precipitated synthetic polymer, has been conjugated together with a monoclonal antibody and utilized as a novel separation method for an immunoassay. PNIP precipitates out of water above a critical temperature of 31 degrees C, enabling a polymer-bound immune complex to be separated from the solution. These characteristics were used to develop a novel polymer-mimetic enzyme immunoassay method for determination of alpha-1-fetoprotein (AFP) with hemin as a labeling reagent to catalyze the reaction of p-hydroxyphenyl acetic acid (HPA) and hydrogen peroxide in alkaline medium. After a one-step competitive immunoreaction, the polymer-antibody-antigen-hemin conjugate moiety was determined by coupling the fluorogenic reaction of HPA and hydrogen peroxide, The calibration graph for AFP was linear over the range of 0-380 ng cm(-3) with a detection limit of 1.0 ng cm(-3). This method combines some advantages of both homogeneous and heterogeneous immunoassays, and has been applied to determine AFP in human blood serum with satisfactory results
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