Adsorption of carbon dioxide onto BDA-CP-MS41

Carbon dioxide was adsorbed onto mesoporous adsorbent of butylene diamine immobilized CP-MS41 (BDA-CP-MS41), which was synthesized by chloropropyl functionalized MCM-41 (CP-MS41) with butylene diamine in a laboratory-scale packed-bed. The adsorber was operated batchwise with the charge of adsorbent in the range of 1–3 g to obtain the breakthrough curves of CO₂. Experiments were carried out at different adsorption temperatures (20–40 °C) and flow rates of nitrogen (10–20 cm³/min) to investigate the effects of these experimental variables on the breakthrough curves. The deactivation model was tested for these curves by combining the adsorption of CO₂ and the deactivation of adsorbent particles. The observed values of the adsorption rate constant and the deactivation rate constant were evaluated through analysis of the experimental breakthrough data using a nonlinear least squares technique. The experimental breakthrough data fitted very well to the deactivation model than the adsorption isotherm models in the literature.     

Surface functionalization of SBA-15 particles for ibuprofen delivery

We have synthesized SBA-15 particles and functionalized their surface with different functional groups (amine, diamine, and sulfonic acid groups) to use them as carrier materials in drug delivery. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen sorption, and zeta potential measurements were used to characterize the synthesized particles. After surface functionalization, the surface of the sulfonic acid-functionalized particles was more acidic than that of the other particles. Using ibuprofen as a model drug, we found that the release rate increased at higher pH. Furthermore, the particles with the sulfonic acid groups exhibited higher release rate than those with the amine and diamine groups. We explained the difference in the release rate using different electrostatic interaction between drug and particle surface that was caused by the surface functionalization. These results should enable design of drug carrier materials based on the SBA-15 particles with the desired release rate.     

Homogeneously distributed magnetite in the polystyrene spherical particles using the miniemulsion polymerization

The polystyrene spherical particles with homogeneously distributed magnetites were prepared using the conventional miniemulsion polymerization. In the first, the magnetite nanoparticles were coated with oleic acid in aqueous Fe³⁺/Fe²⁺ solution using excess ammonium hydroxide via co-precipitation method. In the second, the miniemulsion polymerization of styrene was carried out using various concentrations of potassium persulfate (KPS) as an initiator, H-08E as an emulsifier, hexadecane as a co-emulsifier and acrylic acid as a dispersing agent in the presence of oleic acid coated magnetite at 70 °C for 24 h. The particle size and its distribution of the homogeneously embedded magnetites were influenced by the concentration of the initiator (KPS) and acrylic acid (AAc). In addition, the emulsifier, H-08E, affects the size and the shape of the PS particles. The optimum conditions for the homogeneously distributed magnetite in the spherical PS particles with the narrow distribution were 5 wt.% styrene, 0.2 g KPS, 0.2 g AAc, and 0.12 g H-08E by inducing 364 nm in diameter, 12.04% in the coefficient of variation (C_v) and 22.1% of the maximum magnetite content.     

Fracture behavior of Cu-cored solder joints

Copper-cored solder can be regarded as the next-generation solder for microelectronic semiconductors exposed to harsh operating conditions owing to its excellent sustainability under extreme thermal conditions, e.g., in microelectronic semiconductors used in transportation systems. Cu-cored solder joints with two different coating layers, Sn–3.0Ag and Sn–1.0In, were compared with the baseline Sn–3.0Ag–0.5Cu solder. The fracture strength and failure mode were examined using the high-speed ball-pull and normal-speed shear tests. The Cu-cored solder joint with the Sn–1.0In plating layer exhibited the highest ball-pull and shear strengths. In addition, it showed a much lower percentage of interface fracture between the Cu-core and plating layer than the interface fracture percentage in the Sn–3.0Ag plating layer due to the improved wettability between the Cu-core and Sn–1.0In plating layer.     

Control of serial sampling systems

In industrial multivariable plants, it is often the case that the plant outputs are detected not simultaneously but serially. The problem of estimating the state vector of the plant based on the data obtained from such a detection scheme is considered, and a special type of observer (referred to as a serial-sampling type) which renews its internal state whenever new data are obtained is proposed. The constructability of a serial-sampling observer and the stability of the closed-loop system which includes such an observer are theoretically studied     

Cloning and sequencing of the pyrG encoding cytidine 5''-triphosphate synthetase from Mycobacterium bovis BCG

Treatment of estrogen receptor (ER)-negative MDA-MB-468 human breast cancer cells with 10 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced formation of a nuclear aryl hydrocarbon (Ah) receptor complex as determined by ligand-binding and gel electrophoretic mobility shift assays. TCDD also induced CYP1A1-dependent activity in MDA-MB-468 cells, which represents the first ER-negative Ah receptor-positive human breast cancer cell line that has been identified. Treatment of this cell line with TCDD and related compounds also caused a 50% inhibition of cell growth, which resembled the growth inhibitory effects previously reported for epidermal growth factor (EGF). However, EGF expression is minimal in this cell line and is not induced by TCDD; moreover, EGF and TCDD induced a different pattern of oncogene expression and apoptosis in MDA-MB-468 cells. In contrast, TCDD caused a rapid and sustained induction of transforming growth factor alpha (TGF alpha) gene expression and secreted protein (nearly 2-fold); moreover, the growth-inhibitory effects of TCDD could be blocked by antibodies to the EGF receptor. In a separate experiment, it was shown that TGF alpha also inhibited growth of MDA-MB-468 cells. The results of this study indicate that the mechanism of growth inhibition of MDA-MB-468 cells by TCDD is due to induction of TGF alpha, which is a potent antimitogen in this cell breast cancer line.     

Kinetics for Singlet Oxygen Formation by Riboflavin Photosensitization and the Reaction between Riboflavin and Singlet Oxygen

ABSTRACT: The formation of singlet oxygen by riboflavin and the kinetics and mechanisms of riboflavin degradation in aqueous solution under light were determined. The singlet oxygen formation rate by riboflavin was 2.31 μmole oxygen/mL headspace/h of serum bottle. The degradations of riboflavin were 66% in D₂O and 40% in H₂O, respectively, under light after 24 h. The results indicate that singlet oxygen is involved in riboflavin destruction under light. The riboflavin destructions were 94.0% and 15.7% with 0 mM or 160 mM ascorbic acid, respectively, under light after 96 h. The reaction rate between riboflavin and singlet oxygen was 1.01 × 10¹⁰/M/s, which is a diffusion-controlled reaction rate. This explains the extremely fast degradation of riboflavin in foods under light. Ascorbic acid and sodium azide reduce the degradation of riboflavin under light with different quenching mechanisms. Ascorbic acid quenched both singlet oxygen and excited triplet riboflavin. Sodium azide quenched only the singlet oxygen in riboflavin solution with a quenching rate of 1.547 × 10⁷/M/s. With the involvement of both the Type-I and Type-II mechanisms in the riboflavin degradation under light, singlet oxygen quencher alone could not protect the riboflavin from degradation completely. Addition of ascorbic acid can protect riboflavin oxidation in foods exposed to light.