Topologically‐based characterizations of the existence of solutions of optimization‐related problems

Necessary and sufficient conditions for the existence of solutions of optimization‐related problems, defined on general sets, are established by using topologically‐based structures, without the usual linear structure. First, we prove that the existence of solutions to a variational relation problem is equivalent to the existence of either a KKM‐structure or a connectedness structure, satisfying additionally some verifiable conditions. Then, applying these results, we obtain such full (two‐way) characterizations for the existence of invariant points, solutions of quasiequilibrium problems of the Stampacchia‐Minty type, saddle points, and Nash equilibria for noncooperative games. The main advantages of our scheme with the mentioned two structures are that full characterizations for existence are obtained in a unified way, with no convexity assumptions, and also that one has flexibility to choose a suitable structure in investigations. (This flexibility is decisive when the natural underlying structure of the given problem is scarcely employed.)     

Study of the isomeric ratios in 107Ag(γ, n)106m,gAg reaction of natural silver induced by bremsstrahlungs with endpoint energies in the giant dipole resonance region

We measured for the first time the isomeric ratios in ¹⁰⁷Ag(γ, n)^106m,gAg reaction by using the activation method and γ-ray spectroscopic method for the whole giant dipole resonance region. The high-purity natural Ag foils in disc shape were irradiated with bremsstrahlungs generated from an electron accelerator Microtron. The induced gamma spectra in the irradiated foils were measured by the high resolution γ-ray spectroscopic system which consists of a high-purity germanium detector and a multichannel analyzer. In order to improve the accuracy of the experimental results, necessary corrections were made in the γ-ray activity measurements and data analysis. The results were analyzed, discussed and compared with those of other authors. For the above mentioned reaction, the isomeric ratios in the energy range from 14 to 24 MeV bremsstrahlungs in this work (except the values at 14, 18 and 20) are new measurements.     

Investigation on the reaction of iron powder mixture as a portable heat source for thermoelectric power generators

This paper reports our investigation on the thermal behavior and ignition characteristics of iron powder and mixtures of iron with other materials such as activated carbon and sodium chloride in which iron is the main ingredient used as fuel. Thermal analysis techniques such as differential scanning calorimetry (DSC) and thermogravimetric analysis were used to characterize the materials and for further understanding of reaction kinetics of the pyrophoric iron mixtures. The experimental results demonstrated that iron micron particles react exothermically to the oxygen in atmosphere and produced iron oxide with ignition temperature of 427.87 °C and heat generation of 4,844 J g^?1. However, in this study, the pyrophoric iron mixture acts as a heat source for the thermoelectric power generators, the final mixture composition is determined to compose of iron powder, activated carbon, and sodium chloride with the mass ratio of approximately 5/1/1. The mixture generated two exothermic peaks DSC curves that showed ignition temperature of 431.53 and 554.85 °C and with a higher heat generation of 9,366 J g^?1 at higher temperature. The effects of test pan materials and heating rate on the ignition were also examined by DSC method. Kinetic data such as the activation energy (E _a), the entropy of activation (ΔS ^# ), enthalpy of activation (ΔH ^# ), and Gibbs energy of activation (ΔG ^# ) on the ignition processes was also derived from the DSC analysis. From the ignition temperature, heat generation, and kinetics test data, the mass ratio of 5/1/1 proved to generate the most amount of heat with high temperatures for the standalone thermoelectric power generators.     

Pure and cerium-doped zinc oxides: Hydrothermal synthesis and photocatalytic degradation of methylene blue under visible light irradiation

Pristine and cerium-doped zinc oxides with a different dopant concentration between 1 and 5% were fabricated using the hydrothermal method. Prepared materials show direct bandgaps of comparable values. Cerium-doped materials show UV-Vis spectra with broad tails toward the visible light range. Pure zinc oxide displays the flower-like form, while cerium-doped materials possess rod-shaped morphologies. The materials were tested for the degradation performance of methylene blue under visible light irradiation. To elucidate the difference in their performance, further measurements and experiments were conducted. Overall, 3%-cerium doped zinc oxide shows the greatest photocatalytic performance. This is possibly attributed to its rod shape with good uniformity and to the enrichment of oxygen vacancies in its surface layers. Finally, trapping experiments reveal that positive holes and hydroxyl radicals were the predominant active species during the photocatalytic degradation process.     

Doxorubicin Encapsulation Investigated by Capillary Electrophoresis with Laser-Induced Fluorescence Detection

Doxorubicin (DOX) belongs to the group of anthracycline antibiotics with very effective anticancer properties. On the other hand, the cardiotoxic effects limit its application over the maximum cumulative dose. To overcome this obstacle, encapsulation of this drug into the protective nanotransporter such as apoferritin is beneficial. In this study, fluorescent behavior of DOX in various solvents was determined by fluorescence spectrometry, demonstrating the fluorescence quenching effect of water, which is often used as a solvent. It was found that by increasing the amount of the organic phase in the DOX solvent the dynamic quenching is significantly suppressed. Ethanol, acetonitrile and dimethyl sulfoxide were tested and the best linearity of the calibration curve was obtained when above 50 % of the solvent was present in the binary mixture with water. Moreover, pH influence on the DOX fluorescence was also observed within the range of 4–10. Two times higher fluorescence intensity was observed at pH 4 compared to pH 10. Further, the DOX behavior in capillary electrophoresis (CE) was investigated. Electrophoretic mobilities (CE) in various pH of the background electrolyte were determined within the range from 16.3 to ?13.3 × 10 ^?9 m^?2 V^?1 s^?1. Finally, CE was also used to monitor the encapsulation of DOX into the cavity of apoferritin as well as the pH-triggered release.     

Neurotransmitter Transporter Family Including SLC6A6 and SLC6A13 Contributes to the 5‐Aminolevulinic Acid (ALA)‐Induced Accumulation of Protoporphyrin IX and Photodamage,through Uptake of ALA by Cancerous Cells

δ‐Aminolevulinic acid (ALA)‐induced protoporphyrin accumulation is widely used in the treatment of cancer, as photodynamic therapy (PDT). To clarify the mechanisms of ALA uptake by tumor cells, we have examined the ALA‐induced accumulation of protoporphyrin by the treatment of colon cancer DLD‐1 and epithelial cancer HeLa cells with γ‐aminobutyric acid (GABA)‐related compounds. When the cells were treated with GABA, taurine and β‐alanine, the level of protoporphyrin was decreased, suggesting that plasma membrane transporters involved in the transport of neurotransmitters contribute to the uptake of ALA. By transfection with neurotransmitter transporters SLC6A6, SLC6A8 and SLC6A13 cDNA, the ALA‐ and ALA methylester‐dependent accumulation of protoporphyrin markedly increased in HEK293T cells, dependent on an increase in the uptake of ALA. When ALA‐treated cells were exposed to white light, the extent of photodamage increased in SLC6A6‐ and SLC6A13‐expressing cells. Conversely, knockdown of SLC6A6 or SLC6A13 with siRNAs in DLD‐1 and HeLa cells decreased the ALA‐induced accumulation. The expression of SLC6A6 and SLC6A13 was found in some cancer cell lines. Immunohistochemical studies revealed that the presence of these transporters was elevated in colon cancerous cells. These results indicated that neurotransmitter transporters including SLC6A6 and SLC6A13 mediate the uptake of ALA and can play roles in the enhancement of ALA‐induced accumulation of protoporphyrin in cancerous cells.     

Microwave-Assisted Facile and Rapid Friedel–Crafts Benzoylation of Arenes Catalyzed by Bismuth Trifluoromethanesulfonate

The catalytic activity of metal triflates was investigated in Friedel–Crafts benzoylation under microwave irradiation. Friedel–Crafts benzoylation with benzoyl chloride of a variety of arenes containing electron-rich and electron-poor rings using bismuth triflate under microwave irradiation is described. This method allows the preparation of aryl ketones under solventless conditions in good to excellent yields and short reaction time. Bismuth triflate was easily recovered and reused five times without significant loss of the catalytic activity.     

Electrochemically Controlled Growth of AuPt Alloy Nanowires and Nanodendrites

The ability to control the morphology and phase structure of alloy nanowires is essential for the exploitation of their unique functional properties. This report describes the findings of an investigation of the growth mechanism in the electrochemically controlled growth of Au? Pt alloy nanostructures. By using a template‐free alternating‐current deposition method with different combinations of waveform, voltage, and frequency, controllability over the alloy morphology, composition, and phase structure has been clearly demonstrated for the growth of the nanostructures across the gap of two microelectrodes. The growth is proposed to involve an initial facet‐selective nucleation–growth process followed by two competing nucleation–growth pathways that are highly tunable by the applied frequency and voltage. The findings provided new insights into the mechanism that underlies the controlled fabrication of alloy nanowires and nanodendrites with structurally tailorable functional properties.