Modern strategies for protein quantification in proteome analysis: advantages and limitations

Over the last 3 years, a number of mass spectrometry-based methods for the simultaneous identification and quantification of individual proteins within complex mixtures have been reported. Most, if not all, of such strategies apply a two-step approach: the first for the separation of proteins or peptides, and the second uses mass spectrometry to identify and quantify the individual components. To simplify the outcome of both steps, certain chemicals and heavy-isotope-labeling are commonly used in the early stages of sample preparation (except in differential fluorescence labeling protocols). The ultimate goal of these strategies is to be able to identify every protein expressed in a cell or tissue, and to determine each protein's abundance, state of modification, and possible involvement in multi-protein complexes. In this review, an attempt is made to highlight the salient characteristics of the existing strategies with particular attention to their strengths and weaknesses.     

A cubic dual band near-field focused array antenna using composite right/left handed transmission lines

This paper proposes a new method for design of a dual-frequency near field-focused (NFF) antenna. A 4 × 4 array of dual-band patches and a dual-band feed network are designed to provide a phase distribution at 2.4 and 5.8 GHz. Rectangular patches with U-shaped slot be used as the double-band patches. The composite right/left handed transmission lines (CRLH TL) are used in design of a dual-band phase distribution network for the patches. Finally, a three-dimensional cubic structure is proposed to isolate the feed network and thereby improve the antenna performance. A prototype of a cubic dual band 4 × 4 near field focused array antenna is fabricated and tested. The measurement results have good agreement with simulation results.     

Surface Functionalization with Phosphazene Substrates. Part II. Theoretical and Experimental Investigations of the Interactions of Hexachlorocyclophosphazene with Hydroxylated Silicon-based Surfaces

The interaction of hexachlorocyclophosphazene (HCCP) with the hydroxylated silicon-based surfaces is studied by a combination of XPS experimental analysis and theoretical ab initio simulations, including the estimate of the energy barriers via CI-NEB method to determine the minimum energy reaction paths. Several possible, stable chemisorbed configurations are found to exist, whose structural, energetic, and electronic properties have been analyzed in detail. The theoretical results are in good qualitative agreement with available experimental data. In particular, we get indications that water plays a crucial role in the surface functionalization with HCCP, although the presence of a suitable solvent (e.g. tetrahydrofuran, THF) seems to be essential. This paper is dedicated to Prof. Harry R. Allcock and the pioneering discoveries of his research group particularly in polyphospazenes and generally in materials science.     

Monitoring cell substrate interactions in exopolysaccharide-based films reinforced with chitin whiskers and starch nanoparticles used as cell substrates

Exopolysaccharides (EPS) extracted from Nostoc commune cyanobacteria were used to prepare low-adhesion cell substrates for tumor-selective cell growth. The substrates were reinforced with chitin whiskers and starch nanoparticles and characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and tensile tests. Two anchorage independent cells, green fluorescent protein-modified HeLa and THP-1 cells were seeded on the samples to assess their interaction with the composites. The results confirmed the cell–surface interaction of EPS-based composites. The mechanical properties of these films can be tailored by controlling the type and concentration of the reinforcement, which can be used in the design of different types of biomaterials.     

SDS-PAGE under focusing conditions: an electrokinetic transport phenomenon based on charge compensation

A novel method is reported for mass separation of proteins, based on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Unlike conventional SDS-PAGE, in which separation by mass of SDS-laden polypeptide chains is obtained in constant concentration or porosity gradient gels, the present method, called "SDS-PAGE focusing", exploits a "steady-state" process by which the SDS-protein micelles are driven to stationary zones along the migration path against a gradient of positive charges affixed to the neutral polyacrylamide matrix. As the total negative surface charge of such complexes matches the surrounding charge density of the matrix, the SDS-protein complex stops migrating and remains stationary, as typical of steady-state separation techniques. As a result of this mechanism, the proteins are separated in an unorthodox way, with the smaller proteins/peptides staying closer to the application point and larger proteins migrating further down toward the anodic gel end. This results in a positive slope of the Mr vs migration plot, vs a negative slope in conventional SDS-PAGE. Moreover, such a plot is linear (by design), whereas in standard SDS-PAGE it is semi- or even double logarithmic. Particularly advantageous appears the ability of the present method to fine-tune the separation of small-size fragments and tryptic digests, where conventional SDS-PAGE usually fails. Additionally, by exploiting constant plateaus of charges, rather than gradients, it is possible to amplify the separation between species having closely spaced Mr values, down to a limit of approximately 150 Da. This increases the resolution by at least 1 order of magnitude as compared with standard SDS-PAGE, where for a proper separation of two adjacent species, an Mr increment of approximately 3000 Da is needed.     

On Stability of Cellular Neural Networks

The main results about stability of cellular neural networks (CNNs) are reviewed. Some of them are extended and reformulated, with the purpose of providing to the CNN designer simple criteria for checking the stability properties. A particular emphasis is given to the conditions for the stability of CNNs described by space-invariant templates.     

City as Political Form: Four Archetypes of Urban Transformation

Pier Vittorio Aureli focuses on the category of archetype as an alternative to the idea of type. Four examples – the axial streets of Renaissance Rome, the 17th-century Parisian place, the 19th-century independent block in Berlin and the 20th-century Viennese superblock – are explored here to describe the emergence of modern urban forms that explicitly embody power relations.     

采用实际模型对自动齿轮箱凸轮作动器的效率和磨损的研究

本文研究自动齿轮箱凸轮作动器的效率和磨损,着重于接触动力学。采用罚函数方法仿真凸轮和从动杆间接触,该模型基于有限元与连续弹性基础梁理论近似。采用Hertz理论考虑凸轮和从动杆间相对运动时主要曲率的变化计算基础模量。为比较接触力和不同凸轮轮廓的磨损,该模型仿真概括了整个档位。     

Development and characterization of an implantable biosensor for telemetric monitoring of ethanol in the brain of freely moving rats

Ethanol is one of the most widespread psychotropic agents in western society. While its psychoactive effects are mainly associated with GABAergic and glutamatergic systems, the positive reinforcing properties of ethanol are related to activation of mesolimbic dopaminergic pathways resulting in a release of dopamine in the nucleus accumbens. Given these neurobiological implications, the detection of ethanol in brain extracellular fluid (ECF) is of great importance. In this study, we describe the development and characterization of an implantable biosensor for the amperometric detection of brain ethanol in real time. Ten different designs were characterized in vitro in terms of Michaelis-Menten kinetics (V(MAX) and K(M)), sensitivity (linear region slope, limit of detection (LOD), and limit of quantification (LOQ)), and electroactive interference blocking. The same parameters were monitored in selected designs up to 28 days after fabrication in order to quantify their stability. Finally, the best performing biosensor design was selected for implantation in the nucleus accumbens and coupled with a previously developed telemetric device for the real-time monitoring of ethanol in freely moving, untethered rats. Ethanol was then administered systemically to animals, either alone or in combination with ranitidine (an alcohol dehydrogenase inhibitor) while the biosensor signal was continuously recorded. The implanted biosensor, integrated in the low-cost telemetry system, was demonstrated to be a reliable device for the short-time monitoring of exogenous ethanol in brain ECF and represents a new generation of analytical tools for studying ethanol toxicokinetics and the effect of drugs on brain ethanol levels.