Products, cones, and suspensions of spaces with the measure contraction property

This article concerns several geometric properties of metricmeasure spaces satisfying the measure contraction property (MCP),which can be considered as a generalized notion of lower Riccicurvature bounds. We prove that the MCP of spaces descends totheir products and Euclidean cones. We also show that a positivelycurved space in terms of the MCP with a maximal diameter canbe represented as the spherical suspension of some topologicalmeasure space.     

Exiguolide, a new macrolide from the marine sponge Geodia exigua

A new 20-membered macrolide designated exiguolide has been isolated from the marine sponge Geodia exigua, and its structure determined by interpretation of spectroscopic data. Exiguolide specifically inhibited fertilization of sea urchin (Hemicentrotus pulcherrimus) gametes but not embryogenesis of the fertilized egg.     

Effect of Ru crystal orientation on the adhesion characteristics of Cu for ultra-large scale integration interconnects

The adhesion of Cu on Ru substrates with different crystal orientations was evaluated. The crystal orientation of sputter deposited Ru could be changed from (1 0 0) to (0 0 1) by annealing at 650 °C for 20 min. The adhesion of Cu was evaluated by the degree of Cu agglomeration on Ru. Cu films on annealed Ru films with the (0 0 1) crystal orientation showed 28% lower RMS values and 50% lower Ru surface coverage than Cu as-deposited on Ru having the (1 0 0) crystal orientation after annealing at 550 °C for 30 min, which suggest that Cu wettability on the Ru(0 0 1) was better than that on the Ru(1 0 0) plane. The low lattice misfit of 4% between Cu(1 1 1) and Ru(0 0 1) may be the reason for this good adhesion property.     

Mechanical stress control in a VLSI-fabrication process: a method for obtaining the relation between stress levels and stress-induced failures

An ideal fabrication process is designed to minimize mechanical stress in semiconductor devices and to improve device reliability. Mechanical stress levels were predicted by in-house simulations supported by a thin-film database. These stress levels were correlated with stress-induced defects by TEM analysis supported by fail bit addressing on matured megabit SRAMs. Amorphous-doped silicon film with various annealing temperatures were used for the gate electrode to change the mechanical stress in devices and to get the direct relationship between predicted stress levels and stress related defects. The authors describe brief guidelines for suppressing dislocations in the small geometry shallow-trench isolation process utilizing this system. Polysilicon thickness in the W-polycide gate electrode is designed to minimize mechanical stress in the gate oxide and to suppress the gate oxide failure in probe and class tests. Moreover, critical stress generates dislocations during post source/drain ion implantation anneal obtained by a ball indentation method. This indicated that lower temperature anneal is effective in suppressing the dislocations. A two-step anneal was introduced to suppress dislocations and to enable higher ion activation.     

Photochemical deprotection of nitro-substituted benzenesulfenates via photoinduced electron transfer

The photochemical deprotection of alkyl 2,4-dinitrobenzenesulfenate or alkyl 2-nitrobenzenesulfenate was successfully achieved by addition of triethylamine, while it was unsuccessful without triethylamine. The sulfur-oxygen bond cleavage is thought to occur heterolytically in the sulfenate anion radical produced by photoinduced electron transfer with triethylamine.     

Magneto-Optical Measurement of Organic Conductor Using Rotational Cavity System

We have developed a new magneto-optical measurement system using a rotational cavity system equipped with a millimeter vector network analyzer and a 14 T solenoid type super conducting magnet. The measurement can be performed in the transmission configuration down to 1.6 K. The results of the precise angular dependence measurement of quasi-one-dimensional organic conductor (DMET)₂I₃ using the new system are shown, and its Fermi surface will be discussed in connection with the previous reports.     

Accelerated glycosylation under frozen conditions

O-Glycosylations using thiomethyl glycosides as donors were compared under both frozen and unfrozen conditions. In the presence of MeOTf as a promoter, enormous rate acceleration was observed when the glycosylation was conducted in p-xylene below its freezing point.     

Threshold voltage uniformity and characterization of microwaveperformance for GaAs/AlGaAs high electron-mobility transistors grown onSi substrates

We report on DC and microwave characteristics for high electron-mobility transistors (HEMT's) grown on Si substrates by metal-organic chemical vapor deposition (MOCVD). Threshold voltage (V _th) distribution in a 3-in wafer shows standard deviation of V_th (σV_th) of 36 mV with V_th of -2.41 V for depletion mode HEMT's/Si and σV_th of 31 mV with V_th of 0.01 V for enhancement mode, respectively. The evaluation of V_th in a 1.95×1.9 mm² area shows high uniformity for as-grown HEMT's/Si with σV_th of 9 mV for V_th of -0.10 V, which is comparable to that for HEMT's/GaAs. Comparing the V_th distribution pattern in the area with that for annealed HEMT's/Si, it is indicated that the high uniformity of V_th is obtained irrelevant of a number of the dislocations existing in the GaAs/Si. From microwave characteristic evaluation for HEMT's with a middle-(10~50 Ω·cm) and a high-(2000~6000 Ω·cm) resistivity Si substrate using a new equivalent circuit model, it is demonstrated that HEMT's/Si have the disadvantage for parasitic capacitances and resistances originated not from the substrate resistivity but from a conductive layer at the Si-GaAs interface. The parasitic parameters, especially the capacitances, can be overcome by the reduction of electrode areas for bonding pads and by the insertion of a dielectric layer under the electrode, which bring high cut-off frequency (f_T) and maximum frequency of operation (f_max) of 24 GHz for a gate length of 0.8 (μm). These results indicate that HEMT's/Si are sufficiently applicable for IC's and discrete devices and have a potential to be substituted for HEMT's/GaAs     

Estimates for Hyperbolic Equations of Space Dimension 3

We discuss the problem of boundedness fromL^p(Rⁿ) toL^p′(Rⁿ) (1/p+1/p′=1, 1?p?2) of operators of the typeM=F⁻¹e^i?(ξ)a(ξ) F, which is related to the study of hyperbolic equations with constant coefficients. The boundedness is dependent on a geometrical property ofΣ=?⁻¹(1), and its dependence has been exactly determined in the casesn=2, 1?p?2 andn?3,p=1, 2 (M. Sugimoto,Math. Z.215(1994), 519–531;222(1996), 521–531). This paper is devoted to the unsolved case 1<p<2, and a strange phenomenon is exhibited in the simplest casen=3.     

WIDE RANGE DETECTOR USING PARABOLIC CYLINDRICAL MIRROR FOR THz APPLICATIONS

A new, wide-band, high-speed and high-sensitivity THz detector has been developed. The prototype detector consists of a parabolic cylindrical mirror, a long wire antenna and a Schottky barrier diode. Direct detection measurements have shown a stable sensitivity of 150 ± 50 V/W for 1–2 THz without any adjustments. The long wire antenna was fixed at the focus of parabolic cylindrical mirror then it has been realized less operation steps, easy coupling to the external THz signals and a dramatic enhancement in the practicality of this system. The optically polished mirror and frosted surface one showed comparable sensitivities, thus easy polishing and less cost mirror fabrication can be applied for this system. The radiation pattern showed a maximum radiation angle of approximately 23° with its dominant main lobe, which was attributed to the wire antenna character and confirmed good agreements with classical antenna theory.