Low-temperature bonding of surface-activated polyimide to Cu Foil in Pt-catalyzed formic acid atmosphere

Journal of Materials Science: Materials in Electronics - In this study, a two-step process involving oxygen plasma surface activation and thermos-compression in Pt-catalyzed formic acid gas was...     

Comparison of real time suspended sediment transport measurements in river environment by LISST instruments in stationary and moving operation mode

Suspended sediment and particle size measurements were in this study performed with two instruments based on laser diffraction. The measurements were conducted in the river Danube during a 1-year flood, which enabled measurements in a large scale and under conditions with high sediment load. The aim of this study was to compare LISST-SL stationary measurements with LISST-SL moving measurements to gain knowledge for extensive field surveys of large areas. The moving measurements were performed in four different depths along a transect and compared with stationary measurements in five verticals in the same depths. The results showed that the measured suspended sediment concentrations are smaller for the moving measurements compared to the stationary measurements. In addition thus the d₅₀ was smaller for the moving measurements, which is an indicator for the phenomena of non-isokinetic sampling. A comparison of the pump speed of the two operation modes proofed that during LISST-SL moving measurements a non-isokinetic sampling effect occurred. Hence, a suction effect happened, resulting in an underestimation of particles >63 µm. Beside the LISST-SL simultaneously a LISST-STX was used during the field survey to investigate the behavior and the results of the instrument under conditions where it is originally not designed for. However, the predominant suspended sediment concentrations in the river influenced the measurements and thus multiple scattering occurred. As a consequence the measurements of the suspended sediment concentrations showed lower values for the measured suspended sediment concentrations compared to the LISST-SL stationary measurements. It could also be seen that due to the high amount of fine particles, which were transported during the flood event, a re-scattering of light occurred also in case of measurements where the value for the optical transmission was with 0.38 above the standardized used limit of 0.3.     

Enhanced remediation of simulated wastewaters contaminated with 2-chlorophenol and other aquatic pollutants by TiO2-photoassisted ozonation in a sunlight-driven pilot-plant scale photoreactor

Solar photoassisted remediation of a simulated wastewater contaminated with 2-chlorophenol (2-CP) was carried out by various advanced oxidation processes in a pilot-plant-scale Pyrex glass tubular-type photoreactor using solar cell derived electricity to drive the whole setup. The UV-assisted degradation and mineralization (loss of total organic carbon, TOC) of 2-CP in the co-presence of TiO₂ and ozone (UV/TiO₂/O₃) was enhanced significantly compared with ozonation alone (UV/O₃) and conventional TiO₂ photocatalysis in oxygenated dispersions (UV/TiO₂/O₂). The mineralization process was monitored by TOC assays and chloride ion analyzes. The utilization of immobilized TiO₂ was also examined with a TiO₂-coated glass photoreactor and compared with dispersed TiO₂ in aqueous media. In addition, simulated wastewaters contaminated with the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), the endocrine disruptor bisphenol-A (BPA), the anionic surfactants sodium dodecylbenzenesulfonate (DBS) and sodium butylnaphthalenesulfonate (BNS), together with the cationic benzyldodecyldimethyl- ammonium bromide (BDDAB) surfactant were also efficiently remediated under otherwise identical conditions. The TiO₂-photoassisted ozonation of organic wastewater contaminants is a promising synergistic methodology to accelerate the remediation of such wastewaters, even when the TiO₂ is immobilized which can lead to reduced costs of operation.     

Dual-sensitive and folate-conjugated mixed polymeric micelles for controlled and targeted drug delivery

For this study, we prepared a new type of drug carrier with the characteristics of stimuli-responsive transition and tumor-specific recognition through the co-assembly of two series of amphiphilic block copolymers, poly(ε-caprolactone)-b-poly[triethylene glycol methacrylate-co-N-methacryloyl caproic acid] and poly(ε-caprolactone)-b-poly[triethylene glycol methacrylate-co-N-(2-(methacrylamido)ethyl) folatic amide]. The pH-dependent thermal transition and the content of the targeting ligands of the mixed polymeric micelles are well correlated with the chemical structures and compositions of these two copolymers. Doxorubicin-loaded mixed polymeric micelles are stable at body temperature in the neutral condition for prolonged circulation in blood vessels, and demonstrated rapid drug release at acidic pH levels. The cumulative drug release profiles showed a relatively slow release at pH 7.4, and a quick release of 85% in 3 h at pH 5.3. The cytotoxicity tests against FA-positive (HeLa) and FA-negative (HT-29) tumor cell lines suggest that this mixed polymeric micelle system has potential merits as a controlled and targeted drug delivery system.     

A novel material obtained by electropolymerization of polypyrrole doped with [Sn(dmit)3]2−, [tris(1,3-dithiole-2-thione-4,5-dithiolato)-stannate]2−

The synthesis of a novel material obtained by electropolymerization of a solution of pyrrole and [NEt₄]₂[Sn(dmit)₃] (dmit = 1,3-dithiole-2-thione-4,5-dithiolato) in MeCN is reported. The material was characterized by cyclic voltammetry, UV–vis and FTIR spectroscopy and thermal analysis. Cyclic voltammetry at several scan rates showed that the material has electroactivity and undergoes redox processes associated with the conducting polymer and the anion in the same potential range found for [Sn(dmit)₃]²⁻. The coulombic efficiency (ratio Q_a/Q_c) is close to 1 for all scan rates, indicating that the material is electrically stable at several potential sweeps. The FTIR spectrum showed that the [Sn(dmit)₃]²⁻ anion had been inserted in the polypyrrole backbone. Modifications in the vibrational modes associated with the [Sn(dmit)₃]²⁻ complex anion suggest interaction with the polymer. The Ppy/[Sn(dmit)₃] exhibits good thermal stability which is an important feature for application as a material for devices.     

Interface structural defects and photoluminescence properties of epitaxial GaN and AlGaN/GaN layers grown on sapphire

Overall characterization of the GaN and AlGaN/GaN epitaxial layers by X-ray diffractometry and optical spectral analysis is carried out. The layers are grown by metalloorganic gas-phase epitaxy on (0001)-oriented single crystal sapphire wafers. The components of strains and the density of dislocations are determined. The effects of strains and dislocations on the photoluminescence intensity and spectra are studied. The results allow better understanding of the nature and mechanisms of the formation of defects in the epitaxial AlGaN/GaN heterostructures.     

Effects of inert gases on fatigue crack growth and their transportation into subsurface regions in titanium

To clarify the effects of inert gases on the fatigue behavior of titanium, fatigue crack growth tests were carried out in pure inert gases and in vacuum. Fatigue crack growth rates increased, and the fracture surface appearance was changed in inert gases, as compared to those in vacuum. The transportation of inert gases into subsurface regions of fracture surfaces was confirmed using Auger electron spectroscopy. This transportation is considered to be due to the reverse slip of slip planes on which inert gas atoms have adsorbed.     

Assessment and influence of operational parameters on the TiO2 photocatalytic degradation of sodium benzene sulfonate under highly concentrated solar light illumination

Sodium benzene sulfonate (BS) was decomposed in aqueous TiO₂ dispersions under highly concentrated solar light illumination to examine the photocatalytic characteristics of a parabolic round concentrator (PRC) reactor to degrade the pollutant without visible light absorption. The effects of such operational parameters as initial concentration, volume of the aqueous BS solution, oxygen purging, and TiO₂ loading on the kinetics of decomposition of BS were investigated. An effective photodegradation necessitates a suitable combination of initial volume and concentration of BS solution. Relative to atmospheric air, oxygen purging significantly accelerates the degradation process at high initial concentrations of BS (0.40 mM or 1.0 mM). Optimal TiO₂ loading was 9 g l⁻¹, greater than previously reported. Elimination of TOC (total organic carbon) followed pseudo first-order kinetics in the initial stages of the photodegradation process. The relative photonic efficiency for the photodegradation of BS is ζ_rel=1.0.     

Clustering rows and/or columns of a two-way contingency table and a related distribution theory

The row-wise multiple comparison procedure proposed in Hirotsu [Hirotsu, C., 1977. Multiple comparisons and clustering rows in a contingency table. Quality 7, 27–33 (in Japanese); Hirotsu, C., 1983. Defining the pattern of association in two-way contingency tables. Biometrika 70, 579–589] has been verified to be useful for clustering rows and/or columns of a contingency table in several applications. Although the method improved the preceding work there was still a gap between the squared distance between the two clusters of rows and the largest root of a Wishart matrix as a reference statistic for evaluating the significance of the clustering. In this paper we extend the squared distance to a generalized squared distance among any number of rows or clusters of rows and dissolves the loss of power in the process of the clustering procedure. If there is a natural ordering in columns we define an order sensitive squared distance and then the reference distribution becomes that of the largest root of a non-orthogonal Wishart matrix, which is very difficult to handle. We therefore propose a very nice χ²-approximation which improves the usual normal approximation in Anderson [Anderson, T.W., 2003. An Introduction to Multivariate Statistical Analysis. 3rd ed. Wiley Intersciences, New York] and also the first χ²-approximation introduced in Hirotsu [Hirotsu, C., 1991. An approach to comparing treatments based on repeated measures. Biometrika 75, 583–594]. A two-way table reported by Guttman [Guttman, L., 1971. Measurement as structural theory. Psychometrika 36, 329–347] and analyzed by Greenacre [Greenacre, M.J., 1988. Clustering the rows and columns of a contingency table. Journal of Classification 5, 39–51] is reanalyzed and a very nice interpretation of the data has been obtained.     

Preparation and properties of new tetrafunctional amphoteric surfactants bearing amino,carboxyl, and hydroxyl groups and an ether bond

New amphoteric surfactants of N-(3-alkoxy-2-hydroxypropyl)-N-(2-hydroxyethyl)-β-alanine (APA) have been synthesized. The fundamental surface-active properties (critical micelle concentration and isoelectric point) and hemolysis tests were also investigated to examine the effects of differences in chain length of the alkoxy moiety. The hemolysis result of APA exhibited low constant values irrespective of the alkyl chain length. The amphoteric APA surfactant was confirmed to have a mild effect on human microorganisms and to possess excellent surface-active properties. In addition, a speculative model of micelle configuration was estimated by semiempirical molecular orbital simulations.