Kinetics of aluminum dross dissolution in sec-butyl alcohol for aluminum sec-butoxide

Al sec-butoxide (ASB) has been used as a precursor for activated aluminas but its cost is higher than any other type of precursor. This study was carried out on the dissolution kinetics for synthesis of the ASB from Al dross waste. The reaction was performed under the molar ratio of Al dross and sec-butyl alcohol (SBA) of 3 mol SBA/mol Al with a catalyst of 10^?3 mol HgI₂/mol Al and three different dissolution temperatures of 80, 90 and 100 °C. The Al reactant was used with Al dross of 3–5 mm size range. As a result of the experiment, the dissolution reaction gave a 65% yield after 24 h. The dissolution mechanism was determined by the shrinking core model assumed by the shape of spherical particles. Especially, the kinetic data were well fitted by a chemical reaction in the model. By the Arrhenius equation, the apparent activation energy was determined to be 40.9 kJ mol^?1 at the given reaction temperatures.     

Flexible photodiodes constructed with CdTe nanoparticle thin films and single ZnO nanowires on plastics

We construct a flexible pn heterostructured photodiode using a CdTe nanoparticle thin film and a single ZnO nanowire (NW) on a plastic substrate. The photocurrent characteristics of the flexible photodiode are examined under illumination with 325 nm wavelength light and the photocurrent efficiencies at bias voltages of ± 2.5 V are estimated to be 8.0 and 2.1 μA W(-1) under forward and reverse bias conditions, respectively. The photocurrent generation of the pn heterostructured photodiode is dominantly associated with the transport of the photogenerated charge carriers in the single ZnO NW. Furthermore, the operations of our flexible photodiode are investigated in the upwardly and downwardly bent states, as well as in the flat state.     

Electrochemical sensing using quantum-sized gold nanoparticles

This paper describes the electrocatalytic activity of quantum-sized thiolate protected Au(25) nanoparticles and their use in electrochemical sensing. The Au(25) film modified electrode exhibited excellent mediated electrocatalytic activity that was utilized for amperometric sensing of biologically relevant analytes, namely, ascorbic acid and uric acid. The electron transfer dynamics in the Au(25) film was examined as a function of Au(25) concentration, which manifested the dual role of Au(25) as an electronic conductor as well as a redox mediator. The electron transfer study has further revealed the correlation between the electronic conductivity of the Au(25) film and the sensing sensitivity.     

In situ,quantitative characterization of gelation and fusion mechanism in poly(vinyl chloride) plastisols by small angle light scattering (SALS)

The present paper explores an effective means of characterizing structural changes of poly(vinyl chloride) (PVC) particles during gelation and fusion of PVC plastisols with small angle light scattering (SALS). The SALS method was shown to provide an in situ observation of swelling of PVC particles as well as quantitative information of average size of swollen particles while they are in progress of gelation and fusion. In addition, the SALS method enabled one to evaluate the relative solvent power of plasticizers from the manner of increase in the correlation distances.     

Effect of intravenous immunoglobulin G on natural killer cell cytotoxicity in vitro in women with recurrent spontaneous abortion

Intravenous immunoglobulin (IVIg) has been used to treat women with recurrent spontaneous abortion (RSA), particularly for women with elevated natural killer (NK) cells. We investigated the effect of IVIg on peripheral blood NK cell activity in vitro in women with RSA. 51Cr-release assays using K562 in the presence of varying concentrations of IVIg were performed using PBL from 16 women with RSA. Antibody dependent cellular cytotoxicity (ADCC) was evaluated using Daudi cells. Effectors and targets were preincubated with IVIg. Binding of IVIg to K562 and Daudi was evaluated by flow cytometry. The effect of K562 absorbed IVIg on NK activity was compared to that of non-absorbed IVIg. NK cytotoxicity and ADCC in the presence of F(ab')2 fragments were compared with those in the presence of intact IVIg. IVIg produced a significant, dose dependent inhibition of NK activity in vitro. Inhibition of NK activity occurred when effectors but not targets were preincubated with IVIg. IVIg binds to K562 and Daudi. IVIg increased ADCC when targets but not effectors were incubated with IVIg. K562 absorbed IVIg produced more inhibition of NK cytotoxicity than non-absorbed IVIg. Suppression of NK cytotoxicity by F(ab')2 was as effective as that of IVIg. However, F(ab')2 did not increase ADCC. IVIg effectively reduces peripheral blood NK cytotoxicity in vitro. Inhibition of NK cytotoxicity is mediated at the effector cell level through the antigen binding portion of the immunoglobulins. Women with RSA and elevated NK cells may benefit from IVIg treatment.     

Robust control of robot manipulator by model-based disturbance attenuation

In this letter, a model-based disturbance attenuator (MBDA) for robot manipulators is proposed and the stability of the MBDA in robot positioning problems is proved via Liapunov's direct method. This method does not require an accurate model of a robot manipulator and takes care of disturbances or modeling errors so that the plant output remains relatively unaffected by them. The output error due to the gravity or constant disturbance can be effectively eliminated by this method.     

Aromatization of propane over Zn/HZSM-5 catalysts prepared by chemical vapor deposition

Zinc was introduced into HZSM-5 by chemical vapor deposition (CVD) to investigate the catalytic properties of Zn/HZSM-5 for propane conversion. Irrespective of catalytic precursor or ion exchange method, protons were found to be replaced by Zn ions. However, Zn species in the zeolite were different depending on the precursors used. Although the addition of Zn decreased the intensity of the BrÕnsted acidity, it did not caused the apparent formation of Lewis acid sites unlike Ga/HZSM-5 catalysts. On Zn/HZSM-5, both Zn and protons intervene in propane activation step.     

The First Inert and Photostable Encapsulated Lanthanide(III) Complexes Based on Dendritic 9,10‐Diphenylanthracene Ligands: Synthesis,Strong Near‐Infrared Emission Enhancement,and Photophysical Studies

A series of inert and photostable encapsulated lanthanide(III) complexes—based on dendritic anthracene ligands—is shown for the first time to exhibit strong near‐IR emission bands via efficient energy transfer from the excited states of the peripheral antenna to the Ln³⁺ ions (Er³⁺, Yb³⁺, and Nd³⁺). A significant decrease in the fluorescence of the anthracene ligand is accompanied by a strong increase in the near‐IR emission of the Ln³⁺ ions. The near‐IR emission intensities of Ln³⁺ ions in the encapsulated Ln³⁺–dendrimer complexes are dramatically enhanced on increasing the generation number (n) of dendrons, owing to site‐isolation and light‐harvesting effects. Furthermore, a first attempt is made to distinguish between the site‐isolation and light‐harvesting effects in the present complexes. Photophysical studies indicate the sensitization of Ln³⁺ luminescence by energy transfer through the excited singlet state of the anthracene ligands, and the energy‐transfer efficiency between the dendritic anthracene ligands and the Ln³⁺ ion is evaluated to be in the range of 90 to 97 %. Their energy‐transfer efficiency is in good agreement with the result that the biexponential decays contain a radiative decay of anthracene units (< ca. 10 %) and an energy‐transfer component (> ca. 90 %) from the excited state of anthracene ligands to the Ln³⁺ ions. Time‐resolved luminescence spectra show monoexponential decays with a lifetime of 2 μs for the Er³⁺ ion 11 μs for the Yb³⁺ ion and 0.7 μs for the Nd³⁺ ion in thin films, and calculated intrinsic quantum yields of the Ln³⁺ ions are in the range of ca. 0.025 to 0.55 %.     

The analysis of ultrasonic signals by partial discharge and noise from the transformer

This paper presents the analysis of ultrasonic signals by the partial discharge in a model transformer as well as by corona in the air at a shielded high-voltage laboratory. In addition, various noises onsite, a 345-kV substation, were measured and analyzed, for example, the vibration by core magnetostriction, cooling pump, cooling fan, onload tap changer (OLTC) operation, OLTC filtering unit operation, and air discharge pulse by corona on the transmission line. Therefore, electrical and mechanical noises onsite were removed using the proper narrow bandpass filter and the noise discrimination algorithm. Also, the developed online ultrasonic detector was applied to detect partial discharge in a 154-kV transformer with a warning level in C/sub 2/H/sub 2/ gas. As a result of an internal inspection, the source of partial discharge was found at the estimated position based on ultrasonic detection and its reliability was verified.