Effect of filler concentration on the phase separation in poly(vinyl acetate)-poly(methyl methacrylate) mixtures

The temperatures and kinetics of phase separation have been studied as a function of filler concentration in a polymer mixture of poly(vinyl acetate)-poly(methyl methacrylate). The filler was shown to have a marked effect on the cloud point position and the phase separation kinetics at various temperatures. The effects observed are dependent upon the component ratio.     

Hybrid FIB milling strategy for the fabrication of plasmonic nanostructures on semiconductor substrates

The optical properties of plasmonic semiconductor devices fabricated by focused ion beam (FIB) milling deteriorate because of the amorphisation of the semiconductor substrate. This study explores the effects of combining traditional 30 kV FIB milling with 5 kV FIB patterning to minimise the semiconductor damage and at the same time maintain high spatial resolution. The use of reduced acceleration voltages is shown to reduce the damage from higher energy ions on the example of fabrication of plasmonic crystals on semiconductor substrates leading to 7-fold increase in transmission. This effect is important for focused-ion beam fabrication of plasmonic structures integrated with photodetectors, light-emitting diodes and semiconductor lasers.     

Influence of Helium and Nitrogen Gases on the Properties of Cold Gas Dynamic Sprayed Pure Titanium Coatings

This study investigates the effect of propellant gas, helium, and nitrogen during cold spraying of titanium coatings. Coatings were characterized by SEM and were evaluated for their deposition efficiency (DE), microhardness, and porosity. In selected conditions, three particle velocities were investigated in which for each condition, the propelling gases?? temperature and pressure were attuned to attain similar particle velocities for each gas. Observations show that loosely bonded particles can be detached by high-pressure supersonic gas stream. Selected coatings were characterized by XPS to analyze the occurrence of oxidation and nitridation. Although generally accepted that coating characteristics can be affected by particle temperature, results show that for the same particle velocity, DE and coating density are also a function of substrate temperature. In addition, a thick and fully dense cold sprayed titanium coating was achieved with optimized spray parameters and nozzle using helium. The corresponding average particle velocity was 1173 m/s.     

Controlling the composition of welding fume in welding with coated electrodes for special applications

A technology of ultrasound seam welding of polyethylene terephthalate films has been developed and ultrasound welding equipment and waveguides with spherical working ends constructed. The amplitude–frequency characteristics of acoustic systems are analysed. The dependence of the strength of welded joints on frequency, welding pressure, welding speed and the amplitude of ultrasound oscillations is determined.     

Euromembrane 2000 highlights membrane-based water treatment technologies

The first instalment of our Euromembrane 2000 round-up, which was published in the January 2001 issue of Membrane Technology, looked at developments in liquid membranes and distillation. The conference also looked in detail at water treatment, and this article, the second in a series of three summaries covering the event that was held in Israel during September last year, considers the role which different types of membranes are now playing in this area.     

A new approach to solving problems of multi‐state system reliability optimization

Usually engineers try to achieve the required reliability level with minimal cost. The problem of total investment cost minimization, subject to reliability constraints, is well known as the reliability optimization problem. When applied to multi‐state systems (MSS), the system has many performance levels, and reliability is considered as a measure of the ability of the system to meet the demand (required performance). In this case, the outage effect will be essentially different for units with different performance rate. Therefore, the performance of system components, as well as the demand, should be taken into account. In this paper, we present a technique for solving a family of MSS reliability optimization problems, such as structure optimization, optimal expansion, maintenance optimization and optimal multistage modernization. This technique combines a universal generating function (UGF) method used for fast reliability estimation of MSS and a genetic algorithm (GA) used as an optimization engine. The UGF method provides the ability to estimate relatively quickly different MSS reliability indices for series‐parallel and bridge structures. It can be applied to MSS with different physical nature of system performance measure. The GA is a robust, universal optimization tool that uses only estimates of solution quality to determine the direction of search. Copyright © 2001 John Wiley & Sons, Ltd.     

Electronic equipment for reading and recording signals from the microstrip vertex detector of the SVD-2 setup

Electronic equipment developed for reading, shaping, and recording signals from microstrip sensors of the vertex detector of the SVD-2 setup is described. The configuration of the vertex detector sensors, construction of signal-reading cards, and structure and functions of the recording modules are considered. The obtained characteristics are analyzed.     

Intracavity Laser Absorption Spectroscopy for flame diagnostics

Intracavity Laser Absorption Spectroscopy (ICLAS) is one of the most sensitive techniques in absorption spectroscopy. Application of this technique to combustion diagnostics offers many important advantages. Since ICLAS is an absorption-based method, it is not limited by the quenching and predissociation effects that compromise the sensitivity of Laser Induced Fluorescence (LIF), one of the most sensitive and widespread techniques applied in combustion diagnostics. For that reason, radicals that are subject to strong collisional quenching or predissociation, such as ¹CH₂ and HCO, can be measured by ICLAS with sensitivity much greater than that of LIF. For the same reason, ICLAS also possesses better sensitivity for NH and HNO. The present paper overviews the ICLAS measurements performed during the last decade in our laboratory and also presents recent results: first-time detection of the HSO radical in flames by ICLAS and application of Fiber Laser Intracavity Absorption Spectroscopy (FLICAS) based on Er-doped fiber laser for in-situ detection of ammonia and hydrogen cyanide in a low-pressure methane/air flame doped with a small amount of ammonia. Avenues for future research are discussed.     

Non‐covalently crosslinked hydrogels displaying a unique combination of water‐absorbing,elastic and adhesive properties

BACKGROUND: Stringent requirements must be satisfied by biomedical adhesives, including biocompatibility, adhesion, cohesiveness and processability. The ability to change mechanical properties in response to environmental changes may also be desirable. In the present work the water‐absorbing, adhesive and mechanical properties of blends based on hydrogen bonding complexes between poly(N‐vinyl pyrrolidone), poly(ethylene glycol) (PEG) and poly[(methacrylic acid)‐co‐(ethyl acrylate)] were investigated. These blends, consisting of pharmaceutical‐grade components, exhibit pH‐sensitive swelling and dissolution, along with rubber‐like elasticity and bioadhesion. RESULTS: Polymer blend films remained intact at pH = 5.6 but underwent dissolution at pH = 7.4, the difference being attributed to deprotonation of acidic side‐chains, with loss of hydrogen bonding and development of charge repulsion. Sol release was primarily due to PEG. Films swelled at low pH instead of dissolving, in a manner that was pH‐dependent but PEG‐independent. Films displayed elastic properties comparable to cured elastomers when mildly swollen, with modulus and ultimate strength decreasing with increasing PEG content. Dry films were nearly tack‐free, but became more adhesive with increasing water content, up to a point where the film dissolved. CONCLUSION: Due to their biocompatibility and dissolution/mechanical properties, the bioadhesive polymer blends investigated may be suitable for numerous biomedical applications. Copyright © 2008 Society of Chemical Industry     

Anti-Inflammatory Activity of N-Docosahexaenoylethanolamine and N-Eicosapentaenoylethanolamine in a Mouse Model of Lipopolysaccharide-Induced Neuroinflammation

The search for methods of cognitive impairment treatment and prevention in neurological and neurodegenerative diseases is an urgent task of modern neurobiology. It is now known that various diseases, accompanied by dementia, exhibit a pronounced neuroinflammation. Considering the significant docosahexaenoic and eicosapentaenoic polyunsaturated fatty acids’ therapeutic potential, we decided to investigate and compare anti-inflammatory activity of their N-acylethanolamine derivatives. As a result, we found that both N-docosahexaenoylethanolamine (synaptamide) and N-eicosapentaenoylethanolamine (EPEA) prevents an LPS-mediated increase in the proinflammatory cytokines TNF-α and IL-6 production in the SIM-A9 microglia culture. In an in vivo experiment, synaptamide reversed an increase in LPS-mediated hippocampal TNF-α and IL-1β, but EPEA did not. However, both compounds contributed to the microglia polarization towards the M2-phenotype. Synaptamide, rather than EPEA, inhibited the Iba-1-positive microglia staining area increase. However, both synaptamide and EPEA prevented the LPS-mediated astrogliosis. A study of BDNF immunoreactivity showed that synaptamide, but not EPEA, reversed an LPS-mediated decrease in BDNF production. Despite the more pronounced anti-inflammatory activity of synaptamide, both compounds were effective in maintaining a normal level of hippocampal long-term potentiation in neuroinflammation. The results indicate a high therapeutic potential for both compounds. However, some tests have shown higher activity of synaptamide compared to EPEA.