Ascent of open-circuit voltage on diamond-like carbon photovoltaic cell by infrared heating-assisted pulsed-laser deposition

Phosphorus-doped diamond-like carbon (DLC) films were deposited on quartz and p-type silicon (p-Si) substrates by pulsed-laser deposition. Open-circuit voltage (V _oc) and short-circuit density (I _sc/cm²) from a heating process converted from one type of electrode to another and the two types of electrode pattern are shown by the V–I characteristics. The first heating process was by a ceramic heater, and the other was by an infrared heater. We adopted two electrode patterns, from a bipectinate electrode and a plot pattern electrode, to measure electric photovoltaic characteristics. We were able to upgrade V _oc and I _sc/cm² to 35∼45 mV, and 0.24 μA/cm², respectively, under infrared heating. V _oc by the plot pattern electrode was over 2 V under infrared heating and ceramic heating did not match this on deposition by the PLD method.     

Second-harmonic-generation microscope using eight-segment polarization-mode converter to observe three-dimensional molecular orientation

We developed a compact polarization-mode converter for microscopy to control three-dimensional polarization at the focus. The converter consisted of two homogeneously aligned liquid-crystal spatial light modulators with eight independently controllable electrodes (segments), and a quarter-waveplate. The converter converted a linearly polarized beam to three polarization modes: two orthogonal linear polarizations and a pseudo-radial polarization. We applied the converter to second-harmonic-generation microscopy and demonstrated the detection of three-dimensional molecular orientation.     

M?ssbauer spectroscopic study on valence-detrapping and trapping of mixed-valence trinuclear iron(III, III, II) fluorine-substituted benzoate complexes

Magnetorheological (MR) fluids are new iron-based materials, whose applications include brakes, dampers, clutches, shock absorbers systems and polishing of optical surfaces (lens and mirrors). They are dependent on the size and shape of particles as the magnetic properties. Interested in the possibility of using iron-rich powders, commonly used in nondestructive testing, ranging in size from a few μm to about 200?μm and lower cost than those commercially used for MR fluids, a study of the structural and magnetic properties of iron-rich metallic particles by X-ray diffraction (XRD) and M?ssbauer spectroscopy (MS) at room temperature has been done. Powders, as received, were separated into particle sizes smaller than 20?μm (sample A) and in the range of 20–38?μm (sample B) because these are the sizes generally required for applications in MR fluids. The particles whose sizes exceed the above values were ground in a high energy planetary mill for 3?h, using different values of rotational speed/time: 200?rpm for one hour, a pause of 10?s, 140?rpm for one hour, pause 10?s and then 175?rpm during the last hour. These powders were sieved to obtain particles smaller than 20?μm (sample C). According XRD results, in all samples, only α-Fe (lattice parameter a = 2,867(2) ?) and Fe₂O₃ (lattice parameter a = 5,037(1) ? and c = 13,755(8) ?) were present. The M?ssbauer spectra were fitted with two sextets. The hyperfine parameters values allowed us to assign the highest relative area spectrum (sextet) corresponding to α-Fe and the second one to Fe₂O₃ in accord to the XRD results. Thus, the preparation method using mechanical milling for diminishing the size of the metallic particles allowed us to get particles with size and magnetic properties that could lead to potentially MR fluids applications.     

Stereoselective vinylogous Mukaiyama aldol reaction of α-haloenals

We have developed a high-yielding and stereoselective vinylogous Mukaiyama aldol reaction (VMAR) of α-haloenals. Contrary to the simple α,β-unsaturated aldehyde, α-haloenals were found to be reactive affording the corresponding VMAR adducts in excellent yields. Some transformations of VMAR adducts by Pd-mediated cross-coupling were also examined in order to demonstrate the synthetic utility of VMAR of α-haloenals.     

Cage-shaped borate esters with tris(2-oxyphenyl)methane or -silane system frameworks bearing multiple tuning factors: geometric and substituent effects on their Lewis acid properties

Boron complexes that contain new tridentate ligands, tris(o‐oxyaryl)methanes and ‐silanes, were prepared. These complexes had a cage‐shaped structure around a boron center and showed higher Lewis acidity and catalytic activity than open‐shaped boron compounds. The cage‐shaped ligands determined the properties of the borates by altering the geometry and were consistently bound to the metal center by chelation. The synthesized compounds were L?B(OC₆H₄)₃CH, L?B(OC₆H₄)₃SiMe, and its derivatives (L=THF or pyridine as an external ligand). Theoretical calculations suggested that the cage‐shaped borates had a large dihedral angle (C_ipso‐O‐B‐O) compared with open‐shaped borates. The geometric effect due to the dihedral angle means that compared with open‐shaped, the cage‐shaped borates have a greater Lewis acidity. The introduction of electron‐withdrawing groups on the aryl moieties in the cage‐shaped framework increased the Lewis acidity. Substitution of a bridgehead Si for a bridgehead C decreased the Lewis acidity of the boron complexes because the large silicon atom reduces the dihedral angle of C_ipso‐O‐B‐O. The ligand‐exchange rates of the para‐fluoro‐substituted compound B(OC₆H₃F)₃CH and the ortho‐phenyl‐substituted compound B(OC₆H₃Ph)₃CH were less than that of the unsubstituted borate B(OC₆H₄)₃CH. The ligand‐exchange rate of B(OC₆H₄)₃SiMe was much faster than that of B(OC₆H₄)₃CH. A hetero Diels–Alder reaction and Mukaiyama‐type aldol reactions were more effectively catalyzed by cage‐shaped borates than by the open‐shaped borate B(OPh)₃ or by the strong Lewis acid BF₃?OEt₂. The cage‐shaped borates with the bulky substituents at the ortho‐positions selectively catalyzed the reaction with less sterically hindered substrates, while the unsubstituted borate showed no selectivity.     

Collision-induced dissociation of glycoside–alkali metal adduct ions in fast atom bombardment mass spectrometry

The collision-induced dissociation (CID) spectra of glycoside–alkali metal adduct ions [M + C]⁺ (C = Li, Na, K and Rb) produced under fast atom bombardment (FAB) conditions are reported. The results obtained suggested that the CID spectra of the [M + C]⁺ ions of some flavonoid glycosides reflect the coordination structures because the CID patterns generally changed with the metal cation size. In diglycosides, the CID spectra showed that the relatively small cations Li⁺ and Na⁺ rather bind to the sugar moiety, whereas the large cations K⁺ and Rb⁺ rather bind to the aglycone moiety. In monoglycosides, the cations C⁺ rather bind to the aglycone moiety. It was concluded that the CID technique combined with FAB is useful for the structural elucidation of [M + C]⁺ ions and, in principle, the CID spectra reflect the coordination structures in the gas phase.     

Molecular weight between entanglements for linear d-glucans

Dynamic viscoelasticity measurements were carried out for concentrated solutions of linear d-glucans in BmimCl to examine the effect of the linkage between repeating units of glucose on the rheological properties. The values of molecular weight between entanglements (M _e) were determined for four d-glucans: curdlan, pullulan, cellulose, and amylose. From the concentration dependence of M _e, the value of M _e in the molten state (M _e,melt) for each d-glucan was estimated as a material constant. The order of M _e,melt became cellulose?<?pullulan?<?curdlan?<?amylose, indicating that the linkage is actually influential in M _e,melt for the linear d-glucans. The relationship between M _e,melt and the molecular structure of the d-glucans were discussed assuming that the values of M _e,melt for the d-glucans primarily reflect the chain stiffness such as the characteristic ratio C _∞ on the analogy of synthetic polymers. Although the trend was not so clear, it was shown that N _unit is a decreasing function of C _∞ .     

Analysis of reaction products of cocaine and hydrogen peroxide by high-performance liquid chromatography/mass spectrometry

The change of chemical structure of cocaine in the presence of hydrogen peroxide, a main component of hair dye and decolorant treatments, was studied. High-performance liquid chromatography/mass spectrometry (LC/MS) was used for the separation and identification of cocaine derivatives. After a mixture of cocaine and hydrogen peroxide solutions was incubated at 39 degrees C (this temperature is commonly used when the hair is treated with hair dye or decolorant) for 24 h, six reaction products were detected by LC/MS. Two of them were ecgonine methyl ester and benzoylecgonine, which are metabolites of cocaine. The other reaction products were assumed to be ortho-, meta- and para-hydroxycocaines and dihydroxycocaine, in each of which the benzene ring was hydroxylated by the reaction. These five reaction products (except for dihydroxycocaine) were found immediately after mixing cocaine and hydrogen peroxide. Therefore, the above reaction products might be present in the hair of cocaine users that had treated their hair with hair dye or decolorant.     

An efficient procedure for preparation of 2-monoalkyl or 2-monoaryl-3-ethoxycyclobutanones

Optimized reaction conditions for the preparation of various 2-monosubstituted 3-ethoxycyclobutanones are described. 2-Monoalkyl 3-ethoxycyclobutanones were efficiently prepared by the reaction of the corresponding carboxylic acid chlorides and an excess amount of ethyl vinyl ether in the presence of diisopropylethylamine at 90 °C in a sealed tube. 2-Monoaryl 3-ethoxycyclobutanones were prepared by using 2,6-lutidine as a base in the above-mentioned procedure.