Cancellation of spectral spread in highly-efficient optical fibrewavelength converters

A proposed novel technique for highly-efficient optical fibre wavelength converters based on four-wave mixing is demonstrated. The spread spectrum of pump light has been shown to be effective in suppressing stimulated Brillouin scattering, yet results in the spread of the converted spectrum. To avoid this, modulating the pump and signal lights synchronously is proposed. Cancellation of the spectral spread and the highly-efficient wavelength conversion is demonstrated experimentally     

Corrosion resistance of ultrasonic soldered aluminium joint using Zn-based solder alloy

In order to obtain high strength aluminium butt joints with high corrosion resistance, ultrasonic soldering of 1070 and 5056 rods was conducted using quasi-melting Zn–18Sn (mass%) alloy and Zn–38A1 alloy. Ultrasonic vibrations were applied at soldering temperature ranging 533–723 K through aluminium rods without using of a solder bath. To evaluate the corrosion resistance of solder joints, tensile tests were conducted after immersion in a 5% NaCl aqueous solution. Though joint strength decreased with an increase in immersion time in the NaCl aqueous solution because of corrosion in the joints, corrosion resistance of 5056 joints with Zn–38A1 alloy was higher than that of joints with Zn–18Sn alloy irrespective of aluminium base material. The strength of joints with Zn–18Sn alloy rapidly decreased by immersion in the NaCl aqueous solution. In these joints, corrosion occurred locally in the soldered interface. Corrosion potential of these joints was unusually lower than that of the solder alloy. In contrast, corrosion occurred slowly in the solder layer in 5056 joints with Zn–38A1 alloy. Corrosion potential of the joints was equivalent to that of the solder alloy.     

Investigations of anti-inflammatory,antinociceptive, antioxidant and aldose reductase inhibitory activities of phenolic compounds from Sideritis brevibracteata

The Sideritis species are widely used in the treatment of gastrointestinal disorders, rheumatism, cough, the common cold and as a diuretic, and they are commonly used as an herbal tea in folk medicine in Turkey. The teas of Sideritis have unique tastes, pleasant aromas and a transparent yellow colour, and are preferred as a hot beverage. In order to evaluate this information, the crude methanolic extract and the water soluble part of the methanolic extract after partition with chloroform and n-butanol were investigated for their anti-inflammatory and antinociceptive activities. Phytochemical studies performed on the n-butanol extract of the overground parts of Sideritis brevibracteata, which is rich in phenolic compounds with promising activities, resulted in the isolation of six acetylated allose containing 8-hydroxyflavone glycosides and a phenylethanoid glycoside. The structures of the compounds were established by spectroscopic evidence (UV, IR, NMR, MS). Furthermore, these phenolic compounds of S. brevibracteata were studied for anti-inflammatory, antinociceptive, antioxidant and aldose reductase inhibitory activities. The experimental data demonstrated that S. brevibracteata displayed remarkable anti-inflammatory, antinociceptive and antioxidant activities.     

Improvement of electrical characteristics of local BOX MOSFETs by heavily doped structures and elucidation of the related mechanism

We proposed heavily doped silicon between insulators (HDSBI) MOSFETs to improve electrical characteristics of local BOX MOSFETs by using simple structures that combine local BOX regions with additional doped regions. HDSBI MOSFETs have heavily doped regions between local BOX regions, in which acceptors or traps are introduced. Simulated electrical characteristics demonstrated that they can suppress the SCEs and the kink effect, as well as the self-heating effect (SHE), which is suppressed by conventional local BOX MOSFETs. We elucidated how the additional doped regions in HDSBI MOSFETs suppress the SCEs and the kink effect. We concluded that HDSBI MOSFETs are suitable for applications, such as multi-purpose system-on-chip on which both short-channel logic circuits and high drive current circuits are integrated.     

Influence of woody biomass (cedar chip) addition on the emissions of PM10 from pulverised coal combustion

Co-combustion of pulverised coal with a woody biomass, cedar chip was conducted in a lab-scale drop-tube furnace (DTF) to investigate the synergetic interaction between the inorganic elements of different fuels and the emissions of sub-micron particles (particles smaller than 1.0 μm in size, PM₁) and super-micron particles (particles in the size range of 1.0-10 μm, PM₁₊) during co-firing. The mass fraction of cedar chip in fuel blend ranged from 10% to 50%. All the fuels were burnt in air at two furnace temperatures, 1200 and 1450 °C. The results indicate that, under an identical calorific input, combustion of cedar chip alone favored the emission of sub-micron PM₁, which is dominated by volatile elements including K, Ca, Fe, Na and P. A large fraction of K and Na were most probably present as gaseous vapors in the furnace. The other metals mainly condensed into nano-scale nuclei which subsequently coagulated into a variety of sizes in flue gas. Coal combustion alone favored the release of super-micron particles rich in Al and Si. Emission of PM upon co-firing was a function of both cedar chip share and furnace temperature. At a small mass fraction for cedar chip in fuel blend, e.g. 10% tested here, interaction between the inorganic elements of single fuels was insignificant at either furnace temperature. Accordingly, the quantities of PM₁ and PM₁₊ emitted from co-firing at 10% cedar chip were slightly higher than from the combustion of coal alone, due to the contribution of cedar chip. Significant interaction between the inorganic elements of single fuels was observed for co-firing of coal with >10% cedar chip at the furnace temperature of 1450 °C. As has been confirmed, adding 20-30% cedar chip to coal resulted in the shift of approximately 90% of PM₁ and 50% PM₁₊ into coarse ash particles. For the cedar chip-derived alkali vapors and nano-scale/sub-micron particles, the rates of their shift into larger particles were influenced by two competing routes, homogeneous coagulation and surface reaction with coal-derived kaolin. In contrast, the shift of super-micron particles was primarily determined by their collision probability with the coal-derived mineral grains in bulk gas. A sticky surface for particles is also essential. The shift of individual metals into coarse ash differed distinctly from one another.     

A CdTe detector with a Gd converter for thermal neutron detection

A CdTe detector with a Gd converter has been developed and investigated as a neutron detector for neutron imaging. The fabricated Gd/CdTe detector with the 25 μm thick Gd was designed on the basis of simulation results of thermal neutron detection efficiency and spatial resolution. The energy resolution of the Gd/CdTe detector is less than 4 keV, which is enough to discriminate neutron capture gamma rays from background gamma emission. The Gd/CdTe detector shows the detection of neutron capture gamma ray emission in the ¹⁵⁵Gd(n, γ)¹⁵⁶Gd, ¹⁵⁷Gd(n, γ)¹⁵⁸Gd and ¹¹³Cd(n, γ)¹¹⁴Cd reactions and characteristic X-ray emissions due to conversion-electrons generated inside the Gd film. The observed efficient thermal neutron detection with the Gd/CdTe detector shows its promise in neutron radiography application.     

Frequency-selective surface for microwave power transmission

Using an equivalent-circuit model, frequency-selective surfaces (FSS's) with gridded- and double-square elements have been designed and tested for suppressing the harmonics radiation in microwave power transmission system. It is shown that the angular sensitivity of the frequency response of the FSS arrays can be reduced with a combination of TE- and TM-polarized incident waves or a circularly polarized incident waves instead of a single TE- or TM-polarized incident wave. The FSS arrays have also been measured in a microwave anechoic chamber and a good agreement is obtained between the theoretical calculations and experimental results     

Influence of Ni and Co on methanogenic activity and the amounts of coenzymes involved in methanogenesis

The requirement of Ni²⁺ and Co²⁺ addition on methanogenic activity and the coenzymes involved in methanogenesis were investigated in anaerobic continuous cultivation with synthetic wastewater using acetate as the sole carbon source. Addition of Ni²⁺ and Co²⁺ to the synthetic wastewater drastically increased the maximum dilution rate of the cultivation. The concentrations of coenzymes F₄₃₀ and corrinoids in the biomass increased to 0.62 μmol-Ni/g-VSS and 0.67 μmol-Co/g-VSS, respectively with the increase of the dilution rate. Methanogenic activity of the culture broth also increased with an increase of dilution rate. However, without addition of Ni²⁺ and Co²⁺, F₄₃₀ and corrinoids were not detected in the biomass and methanogenic activity was only a trace level at a dilution rate of 0.025 d⁻¹. When the amounts of Ni²⁺ and Co²⁺ added at a dilution rate of 0.6 d⁻¹ were lowered in steps, the concentrations of F₄₃₀ and corrinoids in the biomass and methanogenic activity decreased with decreasing amounts of Ni²⁺ and Co²⁺ added. These results suggest that Ni²⁺ and Co²⁺ were required for the methane-producing reactions via increases of coenzymes F₄₃₀ and corrinoids.