A new photoactive building block for investigation of DNA backbone interactions: photoaffinity labeling of human DNA polymerase beta

The cross-linking of target proteins or nucleic acids to light-activatable ligands is an important tool for elucidating molecular interactions. Through the use of photoaffinity-labeling reagents, several new insights into nucleic acid interactions have been obtained, for example in DNA replication and repair. In most known photoprobes, the applied light-sensitive functionalities are placed directly at the nucleobase or are attached via linkers to either the nucleobase or the phosphate backbone. Here we describe the first photoprobe that bears a light-sensitive aryl(trifluoromethyl)diazirine at the sugar moiety of a DNA oligonucleotide. We devised a route for the synthesis of the modified nucleoside and its incorporation into an oligonucleotide. The photoactive species was proven to be stable under the conditions employed in routine automated DNA synthesis. The modified oligonucleotide was shown by subsequent photolabeling studies of human DNA polymerase beta to form a covalent complex to the enzyme upon irradiation with near-UV light.     

Remediation of waters contaminated with MCPA by the yeasts Lipomyces starkeyi entrapped in a sol-gel zirconia matrix

A single-stage sol-gel route was set to entrap yeast cells of Lipomyces starkeyi in a zirconia (ZrO(2)) matrix, and the remediation ability of the resulting catalyst toward a phenoxy acid herbicide, 4-chloro-2-methylphenoxyacetic acid (MCPA), was studied. It was found that the experimental procedure allowed a high dispersion of the microorganisms into the zirconia gel matrix; the ZrO(2) matrix exhibited a significant sorption capacity of the herbicide, and the entrapped cells showed a degradative activity toward MCPA. The combination of these effects leads to a nearly total removal efficiency (>97%) of the herbicide at 30 °C within 1 h incubation time from a solution containing a very high concentration of MCPA (200 mg L(-1)). On the basis of the experimental evidence, a removal mechanism was proposed involving in the first step the sorption of the herbicide molecules on the ZrO(2) matrix, followed by the microbial degradation operated by the entrapped yeasts, the metabolic activity of which appear enhanced under the microenvironmental conditions established within the zirconia matrix. Repeated batch tests of sorption/degradation of entrapped Lipomyces showed that the removal efficiency retained almost the same value of 97.3% after 3 batch tests, with only a subsequent slight decrease, probably due to the progressive saturation of the zirconia matrix.     

Experimental evaluation of mechanical properties repeatability of SLA polymers for labs-on-chip and bio-MEMS

Microsystem Technologies - Stereolithography (SLA) is a rapid prototyping technique based on photo-polymerization of liquid resin by laser source. The process is well known for many prototyping...     

Low-temperature behavior of the spin-wave energy in the itinerant electron model of ferromagnetism

An exact microscopic formula for the transverse dynamical susceptibility is derived from the spin rotation invariance properties of the model. The same properties allow the definition on a microscopic basis of the effective magnon-magnon interaction. As a concrete application of the above general results we calculate the low-temperature behavior of the spin-wave energy due to magnon-magnon interaction in the long-wavelength limit. For Ni in the parabolic band approximation and strong ferromagnetism limit we haveC ₂ (K)=8.3×10^–5 T ^5/2 K ² meV.     

Study of the microstructure of inkjet-printed P3HT:PCBM blend for photovoltaic applications

Recently, great interest has been devoted to cost-effective alternative energy sources such as organic solar cells because of the mechanical flexibility and the versatility of chemical structure, the low cost of fabrication, and ease of processing. As regards this last point, the possibility to deposit organic materials from solutions at low temperatures makes them employable for fabricating printed solar cells by direct printing methods. In this study, we used the inkjet-printing technology to deposit P3HT blends with various fullerene acceptors ([60]PCBM, [70]PCBM and bis[60]PCBM) dissolved in single solvents, 1,2-dichlorobenzene (DCB) and chlorobenzene (CB), and their mixtures. After optimizing the printing parameters (printhead speed, drop emission frequency, and substrate temperature), the effect of the solvents on the morphology of the photoactive layers was analyzed through Raman spectroscopy and atomic force microscopy. Polymer solar cells with the structure glass/ITO/PEDOT:PSS/blend/Ca/Al were fabricated and characterized by current–voltage (I–V) measurements under 100 mW/cm² AM 1.5G illumination. A comparative study of the performances of the devices was performed based on three different fullerene derivatives, correlating them to the microstructure of the printed blend films. The optimal devices were obtained when the blend films were deposited from a mixture of DCB:CB 4:1 by volume: this was in agreement with the most favorable morphology of these films.     

Considering the energy,water and food nexus: Towards an integrated modelling approach

The areas of energy, water and food policy have numerous interwoven concerns ranging from ensuring access to services, to environmental impacts to price volatility. These issues manifest in very different ways in each of the three “spheres”, but often the impacts are closely related. Identifying these interrelationships a priori is of great importance to help target synergies and avoid potential tensions. Systems thinking is required to address such a wide swath of possible topics. This paper briefly describes some of the linkages at a high-level of aggregation – primarily from a developing country perspective – and via case studies, to arrive at some promising directions for addressing the nexus. To that end, we also present the attributes of a modelling framework that specifically addresses the nexus, and can thus serve to inform more effective national policies and regulations. While environmental issues are normally the ‘cohesive principle’ from which the three areas are considered jointly, the enormous inequalities arising from a lack of access suggest that economic and security-related issues may be stronger motivators of change. Finally, consideration of the complex interactions will require new institutional capacity both in industrialised and developing countries.     

Source Reconstruction of Atmospheric Releases with Limited Meteorological Observations Using Genetic Algorithms

A genetic algorithm is paired with a Lagrangian puff atmospheric model to reconstruct the source characteristics of an atmospheric release. Observed meteorological and ground concentration measurements from the real-world Dipole Pride controlled release experiment are used to test the methodology. A sensitivity study is performed to quantify the relative contribution of the number and location of sensor measurements by progressively removing them. Additionally, the importance of the meteorological measurements is tested by progressively removing surface observations and vertical profiles. It is shown that the source term reconstruction can occur also with limited meteorological observations. The proposed general methodology can be applied to reconstruct the characteristics of an unknown atmospheric release given limited ground and meteorological observations.     

Secondary sulphate aerosols and cirrus clouds detection with SEVIRI during Nabro volcano eruption

Secondary sulphate aerosols (SSAs) and cirrus clouds in the upper troposphere–lower stratosphere (UTLS) are two key atmospheric constituents that can modulate the Earth’s radiative balance. In this article, we present a new preliminary detection algorithm for UTLS SSAs with the Spinning Enhanced Visible and Infrared Imager (SEVIRI) geostationary instrument. This algorithm is used in combination with a well-established existing clouds classification algorithm, to provide, in perspective, a combined tool to better characterize the aerosol–cirrus interactions at the regional scale and at very high temporal resolution, thus potentially contributing to the understanding of the SSAs’ direct–indirect impact on the Earth’s radiative balance. This new combined tool is tested on the Nabro volcano eruption of June–July 2011, which is known to have emitted a great amount of SSA gaseous precursors in the UTLS and to have interacted with the peculiar Asian monsoon dynamics during summer 2011. Although volcanic aerosol–cirrus interactions are not analysed in details at this stage, this work demonstrates that this can be carried out with SEVIRI by introducing a new dedicated SSA product. First results of the new SSA detection algorithm are encouraging towards the use of this combined product.     

Comparative numerical study of FEM methods solving gas damping in perforated MEMS devices

Three different numerical strategies are presented for the estimation of the damping force acting on perforated movable MEMS dampers. Results from the 2D Perforated Profile Reynolds (PPR) method and the simplified 2D ANSYS method are compared with accurate full 3D flow simulations. Altogether, 32 different topologies are compared varying, e.g., the dimensions of the square damper and the square holes, and the number of holes. The case of uniform perforation and perpendicular motion is studied. Oscillation in the low frequency regime is assumed, that is, the compressibility and inertia of the gas are ignored in the study. While the PPR method is in good agreement with the 3D simulations, the forces given by the ANSYS method were considerably smaller. The reasons for this are studied, and a compact expression to explain the small forces is derived.     

Carbohydrate moieties on the in vitro immunoreactivity of soy β-conglycinin

β-Conglycinin is a functional glycoprotein and one of the most important soybean allergens. The aim of the present research was to investigate the role of the N-glycans moieties of β-conglycinin on its in vitro immunoreactivity. The soy allergen was obtained by isoelectric precipitation from commercial soy protein isolate and was enzymatically deglycosylated by PNGase F (Peptide N-Glycosidase F EC 3.5.1.52). In order to optimize deglycosylation conditions different reaction times and allergen concentrations were tested. The extent of deglycosylation was estimated by SDS–PAGE, CZE, RP-HPLC, and MALDI-TOF MS analyses, which provided information related to changes in protein structure. The antigenicity of both native β-conglycinin and its deglycosylated form was evaluated by western-blotting and indirect ELISA employing polyclonal rabbit anti-soybean sera and horseradish peroxidase-labeled goat anti-rabbit IgG while the in vitro allergenicity was assessed by means of indirect competitive inhibition ELISA employing human sera (IgE) of soy allergics. β-Conglycinin was effectively deglycosylated by PNGase F. Data on immunological tests suggested that glycosyl moieties forming this glycoprotein might be involved in its immunoreactivity.