Development of a small X-ray source using an ultraviolet laser and pyroelectric crystal

We investigate a miniaturized X-ray source using an ultraviolet (UV) laser and a pyroelectric crystal and discuss potential applications in medicine. The UV laser is the fourth harmonic of a Nd:YAG laser with a wavelength of 266 nm, repetition rate of 10 Hz, and pulse energy of 40 mJ. The pyroelectric crystal is a LiNbO₃ cylinder of diameter 10 mm and length 6 mm. The prototype X-ray source we fabricated is an aluminum parallelepiped of dimensions 3 × 3 × 5 cm. The X-ray count rate of the X-ray source is maximized at approximately 1,400 cps for UV laser irradiation of approximately 5 min. After 30 min of irradiation by the UV laser, the temperature of the pyroelectric crystal rose from 295 K to 312 K. The principles of X-ray generation ensure that X-ray sources using UV lasers and pyroelectric crystals offer ample opportunity for miniaturization. We believe the X-ray source developed in this work is suitable for medical applications, although further study is needed to address points such as increasing the X-ray count rate and adjusting the temperature of the pyroelectric crystal.     

Surface analysis of nitride layers formed on Fe‐based alloys through plasma nitride process

Nitriding phenomena that occur on the surfaces of pure Fe and Fe? Cr alloy (16 wt% Cr) samples were investigated. An Ar + N₂ mixture‐gas glow‐discharge plasma was used so that surface nitriding could occur on a clean surface etched by Ar⁺ ion sputtering. In addition, the metal substrates were kept at a low temperature to suppress the diffusion of nitrogen. These plasma‐nitriding conditions enabled us to characterize the surface reaction between nitrogen radicals and the metal substrates. The emission characteristics of the band heads of the nitrogen molecule ion (N₂⁺) and nitrogen molecule from the glow‐discharge plasma suggest that the active nitrogen molecule is probably the major nitriding reactant. AES and angle‐resolved XPS were used to characterize the thickness of the nitride layer and the concentration of elements and chemical species in the nitride layer. The thickness of the nitride layer did not depend on the metal substrate type. An oxide layer with a thickness of a few nanometers was formed on the top of the nitride layer during the nitriding process. The oxide layer consisted of several species of N_x‐Fe_y‐O, NO⁺, and NO₂^?. In the Fe? Cr alloy sample, these oxide species could be reduced because chromium is preferentially nitrided. Copyright © 2009 John Wiley & Sons, Ltd.     

Acylglycerols (=Glycerides) from the Glandular Trichome Exudate on the Leaves of Paulownia tomentosa

Chemical investigations of the glandular trichome exudates on the leaves of Paulownia tomentosa (Scrophulariaceae) led to the identification of the thirty acylglycerols (=glycerides) 1 – 30 , including five known ones ( 2, 3, 6, 9 , and 15 ) (Fig. 1). Spectroscopic analysis combined with GC/MS studies of the glycerides and the liberated fatty acids, in the form of trimethylsilyl ether derivatives and trimethylsilylated methyl esters, respectively, established that the constituents belonged to 1,3‐di‐O‐acetyl‐2‐O‐(fatty acyl)glycerols, 1‐O‐acetyl‐2‐O‐(fatty acyl)‐sn‐glycerols, and 2‐O‐(fatty acyl)glycerols, wherein the fatty acyl moiety was either an eicosanoyl or an octadecanoyl group bearing OH and/or AcO groups at the 3‐, 3,6‐, 3,7‐, 3,8‐, or 3,9‐positions. The 1‐O‐acetyl‐2‐O‐[(3R,6S)‐3‐(acetyloxy)‐6‐hydroxyeicosanoyl]‐sn‐glycerol ( 12 ; 20% of the total glycerides), 2‐O‐[(3R,8R)‐3,8‐bis(acetyloxy)eicosanoyl]glycerol ( 17 ; 14%), 2‐O‐[(3R,9R)‐3,9‐bis(acetyloxy)eicosanoyl]glycerol ( 18 ; 12%), and 2‐O‐[(3R)‐3‐(acetyloxy)eicosanoyl]glycerol ( 10 ; 12%) were relatively abundant constituents. The configurations of the stereogenic centers of the fatty acyl moieties were determined by ¹H‐NMR analysis of the monoesters obtained from (R)‐ and (S)‐2‐(naphthalen‐2‐yl)‐2‐methoxyacetic acid ((R)‐ and (S)‐2NMA? OH and the hydroxy‐substituted fatty acid methyl esters (Fig. 2). The configuration at C(2) of the glycerol moiety of the 1‐O‐acetyl‐2‐O‐(fatty acyl)glycerols was determined to be (2S) by chemical conversion of, e.g., G‐2 (= 2 / 3 1 : 10) to (+)‐3‐O‐[tert‐butyl)diphenylsilyl]‐sn glycerol of known absolute configuration.     

Molecular Ionics in Supramolecular Assemblies with Channel Structures Containing Lithium Ions

A novel trilithium compound, Li₃[B(C₆H₄O₂){O(CH₂CH₂O)₃CH₃}₂][N(SO₂CF₃)₂]₂ ( 1 ‐2.0), with solid‐state ionic conductivity was synthesized. The crystal structure of 1 ‐2.0 consists of the one‐dimensional ionic conduction paths. The paths were afforded as a result of the self‐assembled stacking of the component molecules of 1 ‐2.0 with channel structures containing lithium ions. In this supramolecule, one lithium ion holds the component molecules in specific positions to construct a supramolecular structure with thermally stable ionic conduction paths and the others behave as carrier ions exhibiting selective lithium‐ion conductivity. Owing to the existence of both roles for the lithium ions, this electrolyte shows selective lithium‐ion conductivity.     

Uncertainty relations for joint measurements of noncommuting observables

Universally valid uncertainty relations are proven in a model independent formulation for inherent and unavoidable extra noises in arbitrary joint measurements on single systems, from which Heisenberg's original uncertainty relation is proven valid for any joint measurements with statistically independent noises.     

Second-order necessary conditions for domain optimization problems in elastic structures,part 1: Surface traction given as a field

In this paper, domain optimization problems for both linear and nonlinear elastic structures are studied. The first variation and the second variation of the objective function are calculated in terms of the solution, of the first variation of the solution for the primal elastic system, and of the adjoint variables introduced. The adjoint variables obey a (fictitious) linear elastic system in contrast with the nonlinear adjoint systems introduced by Dems and Mróz, and by Dems and Haftka. From these results, the first-order and the second-order necessary conditions that an optimal domain should satisfy are immediately derived.Portions of this paper were presented at the 5th IFAC Symposium on Control of Distributed Parameter Systems, Perpignan, France, 1989. The authors would like to express their sincere thanks to the referees for their critical readings.     

Flavonol glycosides in leaves of two Diospyros species

Fourteen flavonol glycosides including two new compounds were isolated from the leaves of two Diospyros plants (D. cathayensis and D. rhombifolia). The structures of isolated compounds were determined by spectroscopic analysis. The scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical of the isolated compounds was also investigated.     

Effects of manifold components on peak profiles in flow-injection analysis

The effects of pumps, mixing coils and joints on the peak profiles in flow-injection analysis are described. Four reciprocating pumps, three peristaltic pumps, single coils and double coils with helix diameters of 0.4–3 cm and two types of mixing joint were examined. When pumps yielding small pulsations and double coils with small helix diameter were used, well defined and reproducible peaks were obtained and the effects of mixing joints were small.