Optimum contact conditions for miniaturized surface acoustic wave linear motor

This paper reports the successful operation of a 70 MHz driving surface acoustic wave (SAW) linear motor with a miniaturized stator transducer. This paper also deals with an investigation into an optimized slider design for the miniaturized SAW linear motor. The performance of three silicon type sliders, with different projection size, was compared. Output forces of the three sliders were measured with change of pre-load. It was found that the slider with smaller projection tended to produce greater output force.     

A cylindrical micro-ultrasonic motor (stator transducer size: 1.4 mm in diameter and 5.0 mm long)

Ultrasonic motors are suitable for a micro-actuator because of a direct drive, no brake and their simple construction. In order to fabricate micro-ultrasonic motors, a piezoelectric thin film is essential. In this study, a hydrothermal method was adopted to deposit a PZT thin film. The dimensions of the stator transducer were: outer diameter, 1.4 mm; inner diameter, 1.2 mm; and length, 5.0 mm. The resonance frequency of the stator transducer was 227 kHz, and the vibration amplitude was 58 nmp-p at an input voltage of 4.0 Vp-p. The maximum revolution speed was 680 rpm, and the maximum starting torque was 0.67 microNm. The experimental conditions were 20 Vp-p and 5.3 mN pre-load. The motor property versus scale was investigated using an equivalent circuit. The calculated results indicated that the output torque of the 100 microns diameter motor was 27 nNm.     

Fabrication of microstructures on paraffin substrate using laser heating

In this paper, a technique of forming convex microstructures on a paraffin substrate using laser heating is described. This technique makes use of a phenomenon that solid paraffin, melted by continuous laser irradiation, grows into a pillar-shaped structure with a high aspect ratio in a liquid. Two-dimensional structures, such as line- and wall-shaped structures, are available by scanning irradiation. Also, it is possible to fabricate oblique structures with an inclined laser irradiation. In addition, some characteristics of this fabrication method, such as the laser power and the material temperature, are investigated. Furthermore, the mechanism of this fabrication method is presented. PACS 07.10.Cm; 47.55.Pf; 65.40.De; 79.20.Ds; 81.05.-t     

Synthesis of a Hematoside Analog Containing Phytosphingosine and α-Hydroxyfatty Acid

Abstract

The hematoside analog 1 [NeuGcα(2→3)Galβ(1→4)Glcβ(1→1)Cer], which contains a phytosphingosine as a sphingoid base and an α-hydroxyfatty acid, has been synthesized. Coupling of the methyl (methyl 5-benzyloxyacetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero-α- and -β-D-galacto-2-nonulopyranosid)onate 5, prepared from the corresponding 5-acetamido derivative 2, with a lactose derivative 6 afforded sialolactoside 7, which was converted to the corresponding trichloroacetimidate 10. Glycosylation of 10 with the ceramide tribenzoate 12 gave the protected hematoside analog 13, which was deprotected to the hematoside analog 1.     

Liquid dependence of microstructuring on paraffin substrate using submerged laser heating

The dependence of the liquid properties for fabricating convex microstructures on paraffin substrates using laser heating is characterized. By analyzing the heat transfer from the material to the liquid, a highly linear relationship between the heights of the fabricated microstructures and the heat-transfer coefficients is confirmed. In addition, the impact factor of each liquid property is described. With this result, one can predict the features of the shapes of structures prior to fabrication. Moreover, other parameters, such as the buoyant force and the substrate thickness, are also discussed. PACS 07.10.Cm; 47.55.pf; 65.40.De; 79.20.Ds; 81.05.-t     

Constituents of ophiuroidea. 1. Isolation and structure of three ganglioside molecular species from the brittle star Ophiocoma scolopendrina.

Three ganglioside molecular species, OSG-0 (1), OSG-1 (2), and OSG-2 (3) have been obtained from the polar lipid fraction of the chloroform/methanol extract of the brittle star Ophiocoma scolopendrina. The structures of these gangliosides have been determined on the basis of chemical and spectroscopic evidence as 1-O-[(N-glycolyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyl]-ceramide (1), 1-O-[8-O-sulfo-(N-acetyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyll-ceramide (2) and 1-O-[(N-glycolyl-alpha-D-neuraminosyl)-(2-->8)-(N-acetyl- and N-glycolyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyl]-ceramide (3). The ceramide moieties were composed of heterogeneous unsubstituted fatty acid, 2-hydroxy fatty acid and phytosphingosine units. Compounds 2 and 3 represent new ganglioside molecular species.     

Crystal Structures of Mono-, Di-, and Tri(p-tert-butyl)-thiacalix[4]arenes: Dimeric Self-inclusion Behavior

X-Ray crystal structures of the mono-, di-, and tri(p-tert-butyl)-substituted thiacalix[4]arenes (TC4As; 1, 2, and 3, respectively) have beendetermined. TC4As 1–3 adopt a cone conformation and form dimeric self-inclusion units in such a manner that phenol moieties are inserted into the cavity of each molecule. In all the crystal structures of 1–3, lateralface-to-face interactions exist between the phenol rings that do not bear a tert-butyl substituent, and seemingly, this molecular assembly stabilizes the formation of self-inclusion. TC4As 1 and 2 adopt a cone conformation with C₂ symmetry, leading to the formation of rim-to-rim intermolecular hydrogenbonds so as to link the dimeric units up and down. On the other hand, 3 adopts a regular cone conformation with C₄ symmetry to form cyclic hydrogen bonds withinthe rim part of TC4A.     

Inverse electron demand asymmetric cycloadditions of cyclic carbonyl ylides catalyzed by chiral Lewis acids—Scope and limitations of diazo and olefinic substrates

High enantioselectivities (94-96% ee) were obtained for the inverse electron-demand 1,3-dipolar cycloadditions between cyclohexyl vinyl ether and 2-benzopyrylium-4-olate generated via Rh₂(OAc)₄-catalyzed decomposition of o-methoxycarbonyl-α-diazoacetophenone. The reactions were effectively catalyzed by Eu(OTf)₃, Ho(OTf)₃, or Gd(OTf)₃ complexes (10 mol %) of chiral 2,6-bis[(4S,5S)-4,5-diphenyl-2-oxazolinyl]pyridine. The reactions with the other electron-rich dipolarophiles such as allyl alcohol, 2,3-dihydrofuran, and butyl-tert-butyldimethylsilylketene acetal showed moderate enanantioselectivities (60-73% ee). Good to high enantioselectivities (73-97% ee) were also obtained for the cycloadditions between 3-acyl-2-benzopyrylium-4-olates, generated from methyl 2-(2-diazo-1,3-dioxoalkyl)benzoates and butyl or cyclohexyl vinyl ethers, in the presence of binaphthyldiimine (BINIM)-Ni(II) complexes (10 mol %). Under similar conditions, the reaction between methyl 2-(2-diazo-1,3-dioxohexyl)benzoate and 2,3-dihydrofuran was highly endo-selective, and moderately enantioselective (70% ee). For the BINIM-Ni(II)-catalyzed reactions of cyclohexyl vinyl ether, the use of an epoxyindanone as the 3-acyl-2-benzopyrylium-4-olate precursor revealed that the chiral Lewis acid can function as a catalyst for asymmetric induction. The scope of the cyclic carbonyl ylides was extended to those generated from 1-diazo-2,5-pentanedione derivatives, which were reacted with butyl or TBS vinyl ether and catalyzed using the (4S,5S)-Pybox-4,5-Ph₂-Lu(OTf)₃ complex to give good levels of asymmetric inductions (75-84% ee).     

Preparation of 2,2-disubstituted 1,2-dihydro-3H-indol-3-ones via oxidation of 2-substituted indoles and Mannich-type reaction

A novel preparative method for 2,2-disubstituted 1,2-dihydro-3H-indol-3-ones through the oxidation of 2-arylindoles followed by a Mannich-type reaction with carbon nucleophiles is described.