Image of a parametric optimization problem and continuity of the perturbation function

In this note, we consider the notion of the image of a parametric optimization problem and show that the lower semicontinuity and upper semicontinuity properties of its marginal function can be equivalently expressed as two geometric relations in the image space. These results generalize some existing statements in the literature.     

Extension of the CVBEM to higher-order trial functions

The higher-order trial functions, such as the parabolic, cubic, and Hermite cubic polynomial functions, for the complex boundary element method are derived and their computer programs are developed. Using the considered higher-order trial function, models obtained compatible results to the linear trial function model.     

Hole structures of polymers and zeolites probed by two-dimensional angular correlation of annihilation radiation

The two-dimensional angular correlation of annihilation radiation (2D-ACAR) technique has been developed to measure the hole structure of stretched and oriented polymers. The determination of polymer hole structure is demonstrated in a stretched semi-crystalline polyaryl-ether-ether-ketone (PEEK) sample. The atomic scale anisotropy is found to be consistent with the macroscopic scale stretch ratio. Applications of the 2D-ACAR method to image the three-dimensional hole, free-volume, and cavity structures of molecular systems are discussed.     

Fungal biomass with grafted poly(acrylic acid) for enhancement of Cu(II) and Cd(II) biosorption

The biomass of Penicillium chrysogenum was modified by graft polymerization of acrylic acid (AAc) on the surface of ozone-pretreated biomass. The sorption capacity for copper and cadmium increased significantly as a large number of carboxyl groups were present on the biomass surface, especially when the carboxylic acid group was converted to carboxylate ions using NaOH. When modeled using the Langmuir isotherm, the sorption capacities were 1.70 and 1.87 mmol g(-1) for copper and cadmium, respectively. The loaded biosorbent was regenerated using HCl solution and used repeatedly over five cycles with little loss of uptake capacity beyond the second cycle. The sorption of the two metals was time-dependent, and the kinetics fitted the pseudo-second-order equation well. The Freundlich, Langmuir, Temkin, and Dubinin-Redushkevich isotherms were used to model the metal sorption isotherms, and the thermodynamic parameters calculated show that the sorption was spontaneous and endothermic under the condition applied and that the biomass has similar sorption affinities for the two metals. Fourier transform infrared and X-ray photoelectron spectroscopy reveal that carboxyl, amide, and hydroxyl groups on the biomass surface were involved in the sorption of copper and cadmium and ion exchange and complexation dominated the sorption process.     

Flow Injection Analysis of Chloramphenicol by Using a Disposable Wall‐Jet Ring Disk Carbon Electrode

A preanodized screen‐printed ring disk carbon electrode was applied to the determination of chloramphenicol (Ph? NO₂, CAP) by flow injection analysis (FIA). By setting up the first irreversible reduction reaction of Ph? NO₂ to Ph? NHOH at the disk electrode, the following reversible oxidation of hydroxylamine (Ph? NHOH) to the nitroso (Ph? NO) derivative can be monitored/collected at the ring electrode for CAP analysis. The interference from dissolved oxygen and others can thus be avoided by using this approach and precise CAP determination can be easily performed by FIA under aerobic conditions. Preanodization treatment helps to lower the overpotential of the electrochemical reaction of CAP and favors the selective detection in aqueous medium. Under the optimum conditions, ten repetitive determinations at 1 μM and 10 μM CAP resulted in relative standard deviations of less than 4%, indicating good reproducibility of the system. A linear calibration range of 0.1–20 μM with a detection limit of 0.074 μM (S/N=3) was obtained. Veterinary pharmaceutics were finally analyzed by this sensor to validate its practical applicability.     

Production of a bioflocculant by Aspergillus parasiticus and its application in dye removal

Aspergillus parasiticus was found to produce a bioflocculant with high flocculating activity for Kaolin suspension and water-soluble dyes. Results showed that the carbon and nitrogen sources favorable for the production of the bioflocculant were corn starch and peptone, and an optimal condition of 28 °C, initial pH 5–6 and shaking speed of 150 rpm. The highest flocculating efficiency achieved for Kaolin suspension was 98.1%, after 72 h cultivation. The bioflocculant was mainly composed of sugar (76.3%) and protein (21.6%), and an average molecular weight of 3.2 × 10⁵ Da. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectra showed that amino, amide and hydroxyl groups were present in the bioflocculant molecules. The bioflocculant was effective in flocculating some soluble anionic dyes in aqueous solution, in particular Reactive Blue 4 and Acid Yellow 25 with a decolorization efficiency of 92.4 and 92.9%, respectively. The decolorization efficiency was dependent on the flocculant dosage and solution pH. XPS result shows that the amine groups in the bioflocculant were protonated at pH 5, and thus the positive bioflocculant was attracted to the negatively charged dye molecules. The amino and amide groups in the bioflocculant molecule are believed to play an important role in flocculation from the viewpoint of electrostatic interaction.     

The effects of preparation method on the characteristics of alumina-zirconia powders

Two series of Al₂O₃-ZrO₂ powders with various contents of ZrO₂ were synthesized by sol-gel (chemical polymerization) and coprecipitation methods. The effect of ZrO₂ content and preparation method on the structure and texture of the resultant powders were determined. The samples were characterized by nitrogen sorption, thermal gravimetric analysis, X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The sol-gel method yields more homogeneous powder and retards the aggregation of particles. It produces powders with a larger surface area, a smaller pore size, and a narrower pore size distribution than the coprecipitated one. The X-ray diffraction results show that the powders are amorphous at the calcination temperature below 700°C for both methods. Incorporation of zirconia into alumina greatly affects the surface properties of the powders upon heating, exerting a protective effect against sintering, and inhibiting both the crystallization of the -Al₂O₃ phase and the - to -phase transformation. Zirconia is dispersed in alumina matrix and does not form a new structure.     

Band distortions and inversions in FTIR spectra of silicon dioxide on silicon

We report the FTIR spectra as a function of incident angle and polarization of a 307 Å layer of silicon dioxide on silicon substrate. Bands normally obscured in transmission spectra are revealed and can dominate the reflection spectra at incident angles away from normal. Strong band distortions were observed as the incident angle and polarization were varied. Our experimental results are in excellent agreement with calculations based on published optical constants. Thus, quantitative interpretations of IR spectra of silicon dioxide on silicon should be made with caution.