Advanced Materials Research Vol. 222

Abstract: To realize a fine focused electron beam less than several ten nm in diameter, the initial emission angle must be narrowed as much as possible. To control the initial emission angle, we have introduced a suppressor gate below the extractor gate electrode. The paper describes the fabrication of the field emitter array with a built-in suppressor gate.

Abstract: We explored sources of random errors in intensity spectra measured with THz-TDS. Influences of detection accuracies, optical-delay scanning, atmospheric absorption, and intensity fluctuations of fs-laser on the detected THz pulses are discussed based on the standard deviations of measurement data. Those influences on the THz pulses are considerably small and not a predominant cause of the random error.

Abstract: Novel Sugar Dendritic Gd(III)-DTPA complexes for MRI Contrast Agents (CAs) were prepared and evaluated by in vitro and in vivo methods. The sugar dendritic MRI contrast agents had a good blood vessel pool character and drew blood vessels and liver cancers remarkably clearer and longer time enough than the clinically being used Gd(III)-DTPA complex (Magnevist). Phospha sugar derivatives or phosphorus heterocyclic derivatives provided by functional groups such as epoxide, bromide, etc., were prepared and evaluated by the MTT in vitro method. These phospha sugar derivatives showed excellent anti-proliferative effects of leukemia cell lines, e.g., K562 and U937, as well as solid cancer cells in fashions of (i) higher activity, (ii) wider spectra, and (iii) higher selectivity and specificity than Imatinib mesylate (Gleevec), which is one of the most frequently used chemotherapeutical molecular targeting anti-tumour agent.

Abstract: A model of elastic magnetic filaments is developed, which allows investigating the dependence of filament dynamics on such physical parameters as magnetoelastic number (Cm), frequency of magnetic field, coefficient of friction, etc. By numerical simulation of the dynamics of filament shaping under the action of magnetic field it is shown that a characteristic U-like stable shape (hairpins) can form. Such a shape of filament can exist in the case of low-frequency rotating magnetic field. At the frequency increasing the U-like shape transforms to the S-like one. In the present work it is shown that in unsteady magnetic field a flexible magnetic filament “swims” in the direction of magnetic field.

Abstract: The research report is devoted to the development of a new method of nanostructures formation in ITO/p-Si/Al structure with powerful laser radiation and study of its optical and electrical properties for solar cells applications. It was shown that after the structure irradiation by Nd:YAG laser second harmonic, dark current voltage characteristics become diode-like. Increase of ITO/p-Si/Al solar cell efficiency after irradiation by the laser, using photocurrent voltage characteristic method, was shown.

Abstract: CaYAlO4:Eu3+ phosphors have been synthesized by a solid state method, and characterized by X-ray powder diffraction and photoluminescence (PL). Under the excitation of 147 nm, the synthesized phosphors indicated PL characteristics of the Eu3+ center with the main emission peak at a wavelength of 611.5 nm. The emission intensity depended on synthesis temperature and Eu3+ doping concentration. The highest PL intensity was found for the Ca0.97Eu0.03YAlO4 synthesized at 1400°C for 2 h.

Abstract: In the present work, the sinterability and formation of nanosized yttrium iron garnet (Y3Fe5O12), yttrium perovskite ferrite (YFeO3), cobalt, nickel and zinc iron spinel (CoFe2O4, NiFe2O4 and ZnFe2O4, respectively) powders by an aqueous sol-gel processes are investigated. The phase purity of synthesized nano-compounds was characterized by powder X-ray diffraction analysis (XRD). The microstructural evolution and morphological features of obtained transition metal ferrites were studied by scanning electron microscopy (SEM). The possible application of these nanosized transition metal ferrites as ceramic pigments was demonstrated.

Abstract: In this work properties of potential brushite (CaHPO4•2H2O) and hydroxyapatite (Ca10(PO4)6(OH)2) compound cements are investigated. Calcium dihydrogenphosphate monohydrate (MCPM) and α-tricalcium phosphate (α-TCP) were the starting materials for investigated cements. Setting time is controlled by adding setting time retarder – citrate ions and initially unreactive filler - monetite (CaHPO4). Some compositions of obtained cements contain both brushite and hydroxyapatite. However a substantial amount of monetite was present even if it is not added as filler. There is a strong evidence of presence of octacalcium phosphate – a precursor phase for hydroxyapatite that lacks long range order.

Abstract: The decomposition of carbon fiber reinforced plastics (CFRP) was carried out to recover phenolic monomers and carbon fiber (CF) using subcritical water. The total yield of phenolic monomers reached 70.9% at 673K, 20MPa, 45min and 2.5wt% potassium carbonate catalyst. The tensile strength of the recovered CF was about 15% lower than that of a virgin one and it might be acceptable level for industrial use such as filler in polymers. The functional groups on the surface of the recovered CF decreased, comparing with a virgin one. Therefore the oxidation treatment of the recovered CF might be required, when we try to reuse it.

Abstract: A numerical simulation code was developed for estimating the surface temperature of POM wear test with different shapes. By using the developed code, the effect of sliding geometry with various contact areas on the surface temperature was numerically investigated. The simulation results show that the limiting sliding velocity depends on contact area and reaches a peak value at a certain geometry. It was also found that the simulation code leads an exact prediction of limiting velocity in the range of small contact area. This is important since the exact temperature measurement is very difficult in this range.