Numerical prediction of fraction of eutectic phase in Sn−Ag−Cu soldring using the phase-field method

A combination of macroscale solidification simulation and phase-field calculation is employed to predict the volume fraction of the eutectic phase in Sn-4.0 mass% Ag-XCu solder alloys (X=0.5–1.1 mass%). The solidification simulation incorporates the cooling rate in the phase-field simulation. We assume the residual liquid solidifies as eutectic phase when the driving force for the nucleation of Cu₆Sn₅ amounts to a critical value, which is determined based on the experimental data. Though the calculation results depend on the experimental data, the obtained fractions are about 40% for 0.5 mass% Cu and more than 90% for 1.1 mass% Cu alloy, which shows good agreement with the experimental data.     

Changes in the surface structure of the hamster sperm head associated with maturation, in vitro capacitation and acrosome reaction: an atomic force microscopic study

Structural changes of the hamster sperm head surface associated with maturation, capacitation and acrosome reaction were examined by atomic force microscopy. Spermatozoa were taken from the initial segment and distal cauda of the epididymis, washed in a modified Tyrode solution and fixed by glutaraldehyde. Some sperms taken from distal cauda epididymides were incubated with the capacitation medium before fixation. All samples were attached on the glass slide, dried in a critical point drier and observed by atomic force microscopy. The sperm head surface was characterized by the presence of numerous round particles, approximately 40 and 60 nm in diameter. The distribution and density of these particles on the sperm surface were significantly different between the equatorial segment and post-acrosomal region in each sperm, and also between sperms under different conditions. The surface of the equatorial segment was rather smooth in sperms from the initial segment of the epididymis, but had many large (60 nm) particles in sperms from the distal cauda epididymides, suggesting that the large particles were glycoproteins which were secreted from the epididymis and attached to the sperm surface during maturation. The number of these particles dramatically decreased in both capacitated acrosome-unreacted and acrosome-reacted sperms. This finding supports the idea that glycoproteins are removed from the sperm surface during capacitation. Atomic force microscopic studies of the sperm head surface are expected to be used for future molecular studies on the cell surface components involved in the mechanism of maturation, capacitation and acrosome reaction.     

Universal Functions on Complex General Linear Groups

In 1929, Birkhoff proved the existence of an entire function F on with the property that for any entire function f there exists a sequence {a_k} of complex numbers such that {F(ζ+a_k)} converges to f (ζ) uniformly on compact sets. Luh proved a variant of Birkhoff's theorem and the second author proved a theorem analogous to that of Luh for the multiplicative group *. In this paper extensions of the above results to the multi-dimensional case are proved. Let M(n,  ) be the set of all square matrices of degree n with complex coefficients, and let G=GL(n,  ) be the general linear group of degree n over . We denote by (G) the set of all holomorphic functions on G. Similarly, we define ( ). Let K be the (G)-hull of a compact set K in G. Finally we denote by B(G) the set of all compact subsets K of G with K=K such that there exists a holomorphic function f on M(n,  ) with f(0)(f(K)), where (f(K)) is the ( )-hull of f(K). Our main result is the following. There exists a holomorphic function F on G such that for any KB(G), for any function f holomorphic in some neighbourhood of K, and for any >0, there exists CG with max_ZK |F(CZ)−f(Z)|<.     

Synthesis of novel liquid crystals having the perfluoropyrrolidino group

Novel liquid crystals which have the perfluoropyrrolidino group, a heterocyclic perfluoroalkyl group, and which show smectic phases have been synthesized with perfluoro-(2-pyrrolidinopropionyl fluoride) as one of the starting materials. Analogues with a polymerizable functional group also have been prepared and polymerized to give side chain liquid crystal polymers.     

Thin oxide films of silicon by high pressure oxidation

High pressure oxidation of silicon was performed at an oxidation temperature range of 650 to 800°C for thin oxide films with about 300 å thickness. The index of refraction was dependent on an oxidation temperature but independent of the oxidation pressure as 1.475 at 750°C. The dielectric breakdown strength of the oxide film was measured by the voltage ramping,method. The fixed oxide charge about 1.0 × 10¹¹ cm^?2 was also measured from the high frequency C-V measurement. The pulse scanning C-V measurement technique was used to measure the minority carrier generation rate in the depleted surface. The surface generation velocity was slightly dependent on the oxidation temperature and indicated that the fast surface states increased with decreasing oxidation temperature.     

Nuclear size dependence of inclusive particle production

The inclusive production of π⁺, π^?, K⁺, K^?, p and $\text{p}$ for protons incident on carbon and tungsten targets was studied at the Internal Target Area of the Fermilab. We assume an A^α dependence for the inclusive cross sections and report here on the variation of α with incident momentum, transverse momentum and particle species.     

Supplementary Observations on the Chemistry of the Alkaloids of Berberine Series and Related Compounds. III. Fluorescence Spectra of the Alkaloids of Berberine Series and Their Related Compounds

The absorption maxima of the fluorescence spectra of the berberine series alkaloids are broadly distributed between 360 and 560 mμ. The fluorescence spectra of most substances of this series are very monotonous one having a single peak, the spectra of tetrahydrocoptisine and tetrahydroepiberberine are quite exceptional and consist of two wavy bands. The introduction of the auxochrome group into the molecule of “proto” compounds causes the decreasing of the fluorescence intensity and this effect is strongest in case of transition from protoberberine to berberine. That, tetrahydropalmatine does not show the distinct fluorescence spectrum band is the only incomprehensible fact.     

Search for nucleon resonances of mass up to 8.5 GeV

Missing mass spectra were obtained by measuring recoil protons from the reaction p+p→p+X in the Jacobian peak region. Data were taken during the acceleration ramp of the Fermilab machine using an internal hydrogen gas jet target. We observe the well known N¹(1688) and N¹(2190) resonances but no significant structures at higher mass.     

Further evidence for the intramolecular charge-transfer interaction between tropylium ion and remote benzene rings in 9,10-dihydro-9,10-(1,2-tropylio)anthracene tetrafluoroborate and its methyl derivatives

A series of 9,10-dihydro-9,10-(1,2-tropylio)anthracene tetrafluoroborates

has been prepared. The intramolecular charge-transfer interactions in

were confirmed by their UV spectra and pK_R+ values. As a model compound 1,2,3,4-tetrahydro-1,4-(1,2-tropylio)naphthalene tetrafluoroborate ($\text{5}$)_was also examined.     

Ein zus?tzlicher Test zur modernen Theorie der Molekulargewichts-Fraktionierung auf Grund der L?slichkeits-Differenz

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