Origin of anomalous photoinduced transformations in amorphous Ge-based chalcogenide thin films

Anomalous photoinduced transformations in amorphous Ge-based chalcogenide thin films are established as being due to photochemical modification of the surfaces, by photoemission studies. Mass measurements indicate that the giant thickness reduction on irradiation is predominantly due to the loss of material as a result of photogenerated volatile high vapor pressure oxide fractions on the surface. This extrinsic contribution contradicts the models of the phenomenon proposed so far, which are based purely on intrinsic structural transformations.

Adsorption Of Methanol On The Surfaces Of Copper-Alloys - Ups And Eels Studies

Methanol adsorbs molecularly on the surfaces of Cu–Pd alloys at low temperatures and transforms to CH3O or CO on warming, depending upon the alloy composition. On oxygen presorbed Cu–Pd alloy surfaces, adsorption of methanol gives rise to H2O and H2CO. CH3OH adsorbed molecularly on the surfaces of Cu–Au alloys and CH3O is formed only at relatively high temperatures.

Sustainable conversion of cellulosic biomass to chemicals under visible-light irradiation

For the first time, the conversion of crystalline cellulose to valuable chemicals was enhanced by visible-light irradiation using zeolite-based gold nanoparticles (Au-NPs). This plasmon-enhanced photocatalytic conversion significantly improved processing efficiency and achieved a high yield of 60% at relatively low temperature. Moreover, the photocatalytic properties of the photocatalysts varied with the light intensity and the irradiation wavelength.

A study of the effect of N2 reservoir temperature on a 16 μm CO2-N2 downstream-mixing gasdynamic laser

A study of the effect of N2 reservoir temperature on the small-signal gain in a downstream-mixing 16 μm CO2-N2 GDL is presented. It is shown that the small-signal gain decreases with the increase of N2 reservoir temperature. The conditions for reversing this trend are discussed and the results are presented in the form of graphs.

Enhancement of organic phase controlled extraction of copper by activated carbon

The addition of activated carbon particles (Darco-G, average size 4.3,μm) is shown to enhance the initial rate of extraction of copper in a Lewis cell by a mixture of α- and β-hydroxyoximes, when the rate of extraction is controlled by resistances in the organic phase. It is likely that the copper complex is adsorbed by carbon near the interace and partially released in the bulk. The enhancing effect of carbon vanishes when toluene is used as a diluent instead of heptane, presumably because toluene preferentially adsorbs on its surface.

Skin damage to two new mango cultivars during irradiation and cold storage.

Mangoes can express several skin disorders following important postharvest treatments. Responses are often cultivar specific. This paper reports the responses of two new Australian mango cultivars to some of these treatments. 'Honey Gold' mango develops "under skin browning" early during cold storage. This is thought to be partly caused by a discolouration of the latex vessels which then spreads to the surrounding cells. The symptoms appear to be worse in fruit from hotter production areas and that have been cooled to temperatures below 18C soon after harvest. Current commercial recommendations are to cool fruit to 18C, which limits postharvest handling options. Recent trials have confirmed that delayed or slowed cooling after harvest can reduce under skin browning. The defect may also be associated with physical injury to the skin during harvesting and packing. Irradiation is potentially an important disinfestation treatment for fruit fly in Australian mangoes. The 'B74' mango cultivar develops significant skin damage following irradiation, mainly due to discolouration of the cells surrounding the lenticels. Recent results confirmed that fruit harvested directly from the tree into trays without exposure to water or postharvest chemicals are not damaged by irradiation, while commercially harvested and packed fruit are damaged. Several major harvest and postharvest steps appear to increase lenticel sensitivity to irradiation. Further work is required to develop commercially acceptable protocols to facilitate 'Honey Gold' and 'B74' mango distribution and marketing.

X-Ray Structure Of A Ternary Metal-Complex - Copper(Ii) Inosine 5'-Monophosphate Imidazole - Metal-Binding To The N(7) Atom Of The Nucleotide In A Mixed-Ligand System Containing An Aromatic Amine

A ternary metal-nucleotide complex, Na2[Cu(5’-IMP)2(im)o,8(H20)l,2(H20)2h]as~ 1be2e.n4 pHr2ep0a,r ed and its structure analyzed by X-ray diffraction (5’-IMP = inosine 5’-monophos hate; im = imidazole). The complex crystallizes in space group C222, with a = 8.733 (4) A, b = 23.213 (5) A, c = 21.489 (6) 1, and Z = 4. The structure was solved by the heavy-atom method and refined by full-matrix least-squares technique on the basis of 2008 observed reflections to a final R value of 0.087. Symmetry-related 5’-IMP anions coordinate in cis geometry through the N(7) atoms of the bases. The other cis positions of the coordination plane are statistically occupied by nitrogen atoms of disordered im groups and water oxygens with occupancies 0.4 and 0.6, respectively. Water oxygens in axial positions complete the octahedral coordination of Cu(I1). The complex is isostructural with C~S-[P~(S’-IMP),(NH~)~a] m”,o del proposed for Pt(I1) binding to DNA. The base binding observed in the present case is different from the typical ”phosphate only” binding shown from earlier studies on metal-nucleotide complexes containing various other ?r-aromatic amines.

A novel investigation of vapor-phase charge-transfer complexes of halogens with n-donors by electron energy loss spectroscopy

Complexes of I2 with diethyl ether and triethylamine and of Br, with diethyl ether have been investigated in the vapor phase for the first time by employing electron energy loss spectroscopy. Besides the CT bands, blue-shifted vacuum-UV bands of the halogens have been assigned; the amine-I, system appears to exhibit two CT bands,associated with two different excited states of the complex.

A numerical study of thermocapillary flow in a rectangular cavity during laser melting

The surface tension gradient driven flow that occurs during laser melting has been studied. The vorticity-streamfunction form of the Navier-Stokes equations and the energy equation has been solved by the ‘Alternative Direction Implicit’ method. It has been shown that the inertia forces in the melt strongly influence the flow pattern in the melt. The convection in the melt modifies the isotherms in the melt at high surface tension Reynolds number and high Prandtl number. The buoyancy driven flow has been shown to be negligible compared to the surface tension gradient driven flow in laser melting.

Electron-Energy Loss Spectroscopy (Eels) Of Organic-Molecules In Vapor-Phase - Design And Fabrication Of An Indigenous Eel Spectrometer

An indigenous electron energy loss spectrometer has been designed and fabricated for the study of free molecules. The spectrometer enables the recording of low-resolution electronic spectra of molecules inthe vapour phase with ready access to the vacuum ultraviolet region. Electron energy loss spectra of aliphatic alcohols and carbonyl compounds as wellas of benzene derivatives have been recorded with the indigenous spectrometer and the electronic transitions in these molecules discussed.

Effects of Isothermal and Adiabatic Thermal Loadings on Size and Strain Rate Dependence of Copper Nanowire

In the present paper, the size and strain rate effects on ultra-thin < 100 >/{100} Cu nanowires at an initial temperature of 10 K have been discussed. Extensive molecular dynamics (MD) simulations have been performed using Embedded atom method (EAM) to investigate the structural behaviours and properties under high strain rate. Velocity-Verlet algorithm has been used to solve the equation of motions. Two different thermal loading cases have been considered: (i) Isothermal loading, in which Nose-Hoover thermostat is used to maintain the constant system temperature, and (ii) Adiabatic loading, i.e., without any thermostat. Five different wire cross-sections were considered ranging from 0.723 x 0.723 nm(2) to 2.169 x 2.169 nm(2) The strain rates used in the present study were 1 x 10(9) s(-1), 1 x 10(8) s(-1), and 1 x 10(7) s(-1). The effect of strain rate on the mechanical properties of copper nanowires was analysed, which shows that elastic properties are independent of thermal loading for a given strain rate and cross-sectional dimension of nanowire. It showed a decreasing yield stress and yield strain with decreasing strain rate for a given cross- section. Also, a decreasing yield stress and increasing yield strain were observed for a given strain rate with increasing cross-sectional area. Elastic modulus was found to be similar to 100 GPa, which was independent of processing temperature, strain rate, and size for a given initial temperature. Reorientation of < 100 >/{100} square cross-sectional copper nanowire into a series of stable ultra-thin Pentagon copper nanobridge structures with dia of similar to 1 nm at 10 K was observed under high strain rate tensile loading. The effect of isothermal and adiabatic loading on the formation of such pentagonal nanobridge structure has been discussed.

Laser flash photolysis study of triplets of cyclobutanethiones

Five cyclobutanethiones with different chromophores at the 3-position were examined for triplet state behaviour in benzene using laser excitation into their low lying nπ*1 band systems. A weak transient absorption attributable to the triplet state is observed in all these cases. Results concerning triplet lifetimes, intersystem crossing yields (S1 → T1), self-quenching kinetics and kinetics of energy transfer to all-trans-1,6-diphenyl-1,3,5-hexatriene and oxygen and quenching by di-t-butyl nitroxide (DTBN) are presented. Intersystem crossing yields estimated with reference to p,p′-dimethoxythiobenzophenone are roughly unity in all five cases. Self-quenching rates are found to be less than diffusion limited and this is attributed to steric crowding at the α positions (dimethyl group). The rates of oxygen and DTBN quenching compare well with those reported for several other thiones in the literature. No transients other than the triplet were detected in the above cyclobutane-thiones.

Investigation of Deep Defects Due to -Particle Irradiation in n-Silicon

Electrical properties of deep defects induced in n-silicon by -particles of about 10 MeV energy at a dose of 1014 and 1015 cm-2 are studied by DLTS. The levels at Ec -0.18 eV, Ec -0.26 eV, and Ec -0.48 eV are identified as A center, V2 (=/-) and V2 (-/0) on the basis of activation energy, electron capture cross section, and annealing behavior. Two other irradiation related levels at Ec -0.28 eV and Ec -0.51 eV could not be related to any known center.