Investigations of geometrical structure and morphology of samples made of hard machinable materials after wire electrical discharge machining and vibro‐abrasive finishing

In this article the results concerned influence of processing conditions of the wire electrical discharge machining and vibro‐abrasive machining on the surface layer and morphology of samples made of hard machinable materials used in aircraft industry like: Titanium 5553 β, Inconel 617, Hastelloy X and Magnesium AZ31 have been presented. For this purpose the cubic and cylindrical samples made of hard machinable alloys have been prepared using optimal electric parameters of wire‐cut electrical discharge machining and finally they have been polished using circular vibratory finishing technology and different ceramic shaped stones.     

Switchable Fluorescence of Doxorubicin for Label-Free Imaging of Bioorthogonal Drug Release

Monitoring the release and activation of prodrug formulations provides essential information about the outcome of a therapy. While the prodrug delivery can be confirmed by using different imaging techniques, confirming the release of active payload by using imaging is a challenge. Here, we have discovered that the switchable fluorescence of doxorubicin can validate drug release upon its uncaging reaction with a highly specific chemical partner. We have observed that the conjugation of doxorubicin with a trans-cyclooctene (TCO) diminishes its fluorescence at 595 nm. This quenched fluorescence of the doxorubicin prodrug is recovered upon its bond-cleaving reaction with tetrazine. Clinically assessed iron oxide nanoparticles were used to formulate a doxorubicin nanodrug. The release of doxorubicin from the nanodrug was studied under various experimental conditions. A fivefold increase in doxorubicin fluorescence is observed after complete release. The studies were carried out in vitro in MDA-MB-231 breast cancer cells. An increase in Dox signal was observed upon tetrazine administration. This switchable fluorescence mechanism of Dox could be employed for fundamental studies, that is, the reactivity of various tetrazine and TCO linker types under different experimental conditions. In addition, the system could be instrumental for translational research where the release and activation of doxorubicin prodrug payloads can be monitored by using optical imaging systems.     

Dielectric properties of cubic bismuth based pyrochlores containing lithium and fluorine

In this work dielectric properties of Bi_1.5Zn_1?xLi_xNb_1.5O_7?xF_x with x = 0.25 were investigated in a 20 Hz–12 GHz frequency and 120–500 K temperature range and compared to that of regular cubic BZN (when x = 0). Measurements showed that both ceramics have dipolar glass type dielectric dispersion with wide relaxation time distributions. Mean relaxation time follows Arrhenius law in the investigated frequency range, although Vogel–Fulcher law was anticipated.     

Oxidation-abrasion of TiC-based cermets in SiC medium

The aim of the current study was to investigate the effect of oxidation on abrasive wear behaviour of TiC based cermets at temperatures ranging from 20 to 900 °C. Three types of material performance maps were constructed: oxidation rate maps, wear rate maps and maps showing the effect of oxidation on abrasion. Discussion on the performance of different cermet grades is supported by the SEM images combined with EDS and XRD analysis. The results should facilitate the selection of TiC-based cermets providing optimum composition of cermets for high temperature applications.     

Comparative characterization of particle emissions from asbestos and non-asbestos cement roof slates

The first aim of this study was to characterise total and size-fractionated particulate matter (PM) aerosol, including fibres, released from the processing operations of cement roofing slates. The second aim was to compare particle emissions from asbestos-cement and non-asbestos cement sheets, with respect to total and size-fractionated particulate matter as well as fibres emissions. Asbestos and cellulose-based cement sheets were compared during slate treatment processes, namely crushing, rubbing, rasping and scrubbing. Generated PM and fibres were classified by a variety of methods (PM_2.5 and PM₁₀ cyclones, aerodynamic particle spectrometer and optical particle counter). A substantial variation in the mass of generated particles has been noticed, both within each PM fraction and between different treatment processes. The PM₁₀/PM_total concentration ratio ranged from 70 to 98% and PM_2.5/PM_total ratio equalled to ∼20%. The new generation non-asbestos sheets produced three times higher PM emissions than asbestos-cement sheets during crushing operation. Particle size distribution of number concentrations was mostly bimodal (two modes at 0.5 and 2.5 μm). With respect to fibres, the release of cellulose fibres from non-asbestos slates was from 1.8 to 13 times lower in comparison with asbestos fibres. At the same time, cellulose fibre length was 1.4–1.6 times lower. Hence, new generation non-asbestos roofing slates were proved to be less hazardous from the point of view of fibre release, but more hazardous with respect to total particle release.     

Transitioning From Micro to Nano-photonics with Photonic Crystal Fibers

Maksim Skorobogatiy是麻省理工学院物理学博士、加拿大光子晶体研究主席，目前主要研究领域为实际应用的光学纤维的微观结构、纳米光学和电浆子。今年10月Maksim Skorobogatiy博士将应邀出席“2009第八届中国国际纳米科技（湘潭）研讨会”，并做大会特邀报告，报告摘要如下：     

Surface Structure,Spectroscopic and Photocatalytic Activity Study of Polyaniline/TiO2 Nanocomposites

PANI （polyaniline） as a promising conducting polymer and photosensitizer has been used to prepare PANI/TiO2 （polyaniline/TiO2） nanocomposite as photocatalyst. TiO2 nanoparticles with size of 5-100 nm were encapsulated by PANI via the ＂in situ＂ polymerization of aniline on the surface of TiO2 nanoparticles. IR, SEM, EPR techniques were used to characterize the mechanism of electron interaction in PANI/TiO2 nanocomposite. The resulting PANI-modified TiO2 composites exhibit significantly higher photocatalytic activity than that of neat PANI on degradation of MB （methylen blue） aqueous solution under UV irradiation.