Binding and purification of plasmid DNA using multi-layered carbon nanotubes

We propose a new method for the separation of nucleic acids using multi-layered carbon nanotubes (CNTs) as an adsorbent. According to agarose gel electrophoresis, oxidized water-stable CNTs adsorb certain forms of nucleic acids, such as high molecular weight RNA, chromosomal DNA, linear and denatured forms of plasmid DNA. However, CNTs do not adsorb supercoiled form of plasmid DNA. Nucleic acids bound to CNTs can be readily removed by centrifugation whereas supercoiled plasmid DNA remains in solution. Upon the addition of divalent metal ions supercoiled plasmid DNA forms relatively stable complexes with CNTs due to chelation. Thus, new details about association of nucleic acids with CNTs were revealed and stoichiometry of the complexes was estimated. Our results can be used for fine purification of supercoiled plasmid DNA for gene therapy applications as well as manipulation of nucleic acids for biosensor design. © 2011 Elsevier B.V

Nanostructured Silver Substrates With Stable and Universal SERS Properties: Application to Organic Molecules and Semiconductor Nanoparticles

Nanostructured silver films have been prepared by thermal deposition on silicon, and their properties as SERS substrates investigated. The optimal conditions of the post-growth annealing of the substrates were established. Atomic force microscopy study revealed that the silver films with relatively dense and homogeneous arrays of 60–80-nm high pyramidal nanoislands are the most efficient for SERS of both organic dye and inorganic nanoparticles analytes. The noticeable enhancement of the Raman signal from colloidal nanoparticles with the help of silver island films is reported for the first time

Bipolar disorders

Bipolar disorder is characterized by (hypo)manic episodes and depressive episodes which alternate with euthymic periods. It causes serious disability with poor outcome, increased suicidality risk, and significant societal costs. This chapter describes the findings of the PET/SPECT research efforts and the current ideas on the pathophysiology of bipolar disorder. First, the cerebral blood flow and cerebral metabolism findings in the prefrontal cortex, limbic system, subcortical structures, and other brain regions are discussed, followed by an overview of the corticolimbic theory of mood disorders that explains these observations. Second, the neurotransmitter studies are discussed. The serotonin transporter alterations are described, and the variation in study results is explained, followed by an overview of the results of the various dopamine receptor and transporter molecules studies, taking into account also the relation to psychosis. Third, a concise overview is given of dominant bipolar disorder pathophysiological models, proposing starting points for future molecular imaging studies. Finally, the most important conclusions are summarized, followed by remarks about the observed molecular imaging study designs specific for bipolar disorder.</p

Comparability of Raman Spectroscopic Configurations: A Large Scale Cross-Laboratory Study

This is the final version. Available on open access from the American Chemical Society via the DOI in this recordThe variable configuration of Raman spectroscopic platforms is one of the major obstacles in establishing Raman spectroscopy as a valuable physicochemical method within real-world scenarios such as clinical diagnostics. For such real world applications like diagnostic classification, the models should ideally be usable to predict data from different setups. Whether it is done by training a rugged model with data from many setups or by a primary-replica strategy where models are developed on a 'primary' setup and the test data are generated on 'replicate' setups, this is only possible if the Raman spectra from different setups are consistent, reproducible, and comparable. However, Raman spectra can be highly sensitive to the measurement conditions, and they change from setup to setup even if the same samples are measured. Although increasingly recognized as an issue, the dependence of the Raman spectra on the instrumental configuration is far from being fully understood and great effort is needed to address the resulting spectral variations and to correct for them. To make the severity of the situation clear, we present a round robin experiment investigating the comparability of 35 Raman spectroscopic devices with different configurations in 15 institutes within seven European countries from the COST (European Cooperation in Science and Technology) action Raman4clinics. The experiment was developed in a fashion that allows various instrumental configurations ranging from highly confocal setups to fibre-optic based systems with different excitation wavelengths. We illustrate the spectral variations caused by the instrumental configurations from the perspectives of peak shifts, intensity variations, peak widths, and noise levels. We conclude this contribution with recommendations that may help to improve the inter-laboratory studies.COST (European Cooperation in Science and Technology)Portuguese Foundation for Science and TechnologyNational Research Fund of Luxembourg (FNR)China Scholarship Council (CSC)BOKU Core Facilities Multiscale ImagingDeutsche Forschungsgemeinschaft (DFG, German Research Foundation

MATERIALI IN TEHNOLOGIJE

The aim of this study is to determine the microstructure, superconducting and mechanical properties of YBa2Cu3O6 56 (YBCO) and YBCO thin films with a manganese (Mn) addition. All the YBCO superconducting films (undoped and Mn-doped) were dip-coated onto (001) SrTiO3 (STO) single-crystal substrates with a metalorganic deposition using the trifluoroacetate (TFA-MOD) technique. The phase analysis, microstructure, surface morphologies and critical temperature (T-c) of the superconducting thin films were determined with an X-ray diffractometer (XRD), a scanning electron microscope (SEM), an atomic force microscope (AFM) and an inductive T-c measurement system. Since the main issue of this study is to determine the mechanical-property variations of the superconducting thin films with/without a Mn addition, the adhesion strength of these films on a STO substrate was tested with a Shimadzu scratch tester. Depending on the Mn addition, the critical forces of pure films increase from 56.23 mN, 58.63 mN and 60.11 mN for pure YBCO, YBCO with 0.05 g and 0.10 g of Mn. Furthermore, Young's modulus and the hardness of the undoped and Mn-doped YBCO thin films were measured with a CSM Berkovich nanoindenter using the load-unload sensing analysis under a 0.3 mN applied load

MATERIALI IN TEHNOLOGIJE

Superconducting films with poor mechanical properties are useless even if they possess good transport and flux-pinning properties. Since additive particles as pinning centers are important changes in a microstructure, their effect on the micromechanical properties such as Young's modulus and hardness have to be investigated with respect to the additional-particle type and quantity, using experimental and numerical methods. In this study, films were dip-coated onto (001) SrTiO3 (STO) single-crystal substrates with metalorganic deposition using the trifluoroacetate (TFA-MOD) technique. The phase analysis and the microstructure of the superconducting thin films were determined with an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). The mechanical-property variations of the pure YBCO and the YBCO thin films with Mn (reacting as BaMnO3) were experimentally obtained with nanoindentation techniques. Thus, the BaMnO3 nanoparticle effects on the structural and mechanical properties of the films were observed. According to the nanoindentation results, the Young's modulus and indentation hardness of the films decreased from 88.54 GPa to 76.47 GPa and from 12.51 GPa to 3.88 GPa, respectively, depending on the additive particles. In addition, the finite-element modeling (FEM) of the indentation was applied to estimate the failure stress/stress distribution relation at the contact region between the indenter and the surface of a YBCO-based thin film, obtaining the same force/penetration depth curve as with the indentation experiment. According to these main aims of FEM, the mesh-design effect, material properties and the boundary condition of the axisymmetric model were chosen and optimized to obtain the mechanical results of the instrumented indentation

MATERIALI IN TEHNOLOGIJE

Metallurgical welding joints are extensively used in the fabrication industry, including ships, offshore structures, steel bridges and pressure vessels. The merits of such welded structures include a high joint efficiency, water and air tightness, and low fabrication costs. However, residual stresses and distortions can occur near the weld bead due to localized heating by the welding process and subsequent rapid cooling. This paper is focused on deriving a simulation solution to predict the design parameters, such as the temperature-stress distribution, the approximate gradient and the nodal displacement on the plates during the process of submerged arc welding (SAW). During the construction of an AH 36 quality T-beam profile using the SAW process, thermal residual stress and distortion occurs due to heat fusion from the source to the joint part of the symmetric T-beam. The value of the design parameter is achieved by performing a thermal elasto-plastic analysis using finite-element techniques. Furthermore, this investigation provides an available process analysis to enhance the fabrication process of welded structures

JOURNAL OF MATERIALS PROCESSING TECHNOLOGY

The aim of this study is to obtain microstructural characteristics and investigate the mechanical properties such as hardness, Young's modulus and fracture toughness of the boride layer depending on process time and temperature. The produced double layers (FeB and Fe2B) were extensively analyzed with respect to X-ray, diffraction (XRD) and scanning electron microscopy (SEM). The XRD pattern of the boride layers, which were formed on SAE 1020 and 1040 quality steel at 900 degrees C for 2 h, 4 h and 6 h, include only FeB phase on surface with (111), (2 10), (10 1) and (111) planes. SEM cross-sectional investigations show that double-phase boride layer existence from surface to inside of substrate. The structural compositions of layers consist of boron rich phase (FeB) and iron rich phase (Fe2B), respectively. Surface roughness value of samples is important parameter for micro-indentation test with Dynamic Ultra Micro Hardness Tester. After diffusion controlled boriding process, material surface roughness can be high for micro-indentation test. So, surface polishing process is applied for decreasing roughness of FeB layers. Surface roughness values of 2 h, 4 h and 6 b borided SAE 1020 and SAE 1040 quality steel were decreased from 0.9 mu m to 0.05 mu m by polishing process. Mechanical properties of layers were examined by Shimadzu Dynamic Ultra-microhardness test machine for estimating Young's modulus due to load-unload sensing analysis and in addition to mechanical investigation hardness-depth curves of the layer were obtained for estimating indentation depth and load dependency of mechanical properties. Load depended elastic modulus (12S-624 GPa) and hardness (17-33 GPa) were obtained at 80 mN, 160 mN, 320 mN and 640 mN applied peak loads depending on boriding process time. Fracture toughness proper-ties of FeB surface layers were calculated by Vickers Fracture Toughness method for 1 N applied peak load with measuring crack length after loading stage was finished. (c) 2007 Elsevier B.V. All rights reserved

Estimation of FeB layer's yield strength by comparison of finite element modeling with experimental data

In this study, low alloy steel substrates were borided by pack boriding process, for 2, 4 and 6 h at 900 degrees C. Microstructural observations were conducted by using SEM. The structural composition of layers consists of boron rich phase (FeB) and iron rich phase (Fe2B). First, experimental indentation studies were carried out to determine the load-unload curves of FeB layers at different peak loads. Important parameters such as hardness and Young's modulus of FeB layers, and contact area were obtained from experimental indentation test sample data. After the mechanical characterization of samples, finite element modeling was applied to simulate the mechanical response of FeB layer on low alloy steel substrate by using ABAQUS software package program. The unique contribution of this study different from previous methods is the estimation of the yield strength of FeB layer by combining the experimental indentation works and finite element modeling (FEM). (C) 2009 Elsevier Ltd. All rights reserved