Sinusoidal normal stress measurements with the Weissenberg rheogoniometer

In measuring sinusoidal normal stress difference of concentrated polymer solutions in a Weissenberg rheogoniometer, the resistance to motion of the upper platen due to the sample between the cone and plate should be taken into account. Correction terms are derived. The theoretical predictions of Lodge and others concerning the relationship between oscillatory normal stress difference and oscillatory shear stress are found to agree with experimental data if these corrections are applied.     

Highly sensitive all-optical method for measuring magnetic fields

An all-optical method for measuring magnetic fields is described. This method uses a beam-guide type Faraday cell as the field sensor and optical fibers as the transmission line. A laser beam travels through the Faraday cell with multiple passes nearly in the direction of the magnetic field, so that the field sensitivity of the cell becomes very high. The minimum detectability is 0.1G for 50Hz magnetic fields.     

Reaction of carbonyl compounds with trialkylsilyl phenylselenide and tributylstannyl hydride under radical conditions

A novel method for the hydrosilylation of carbonyl compounds has been developed. When carbonyl compounds were allowed to react with trimethylsilyl phenylselenide and tributylstannyl hydride in the presence of a catalytic amount of AIBN as the radical initiator, hydrosilylation of the carbonyl compounds efficiently proceeded to give the corresponding silyl ethers in moderate to good yields. In the absence of carbonyl compounds, the triethylsilyl hydride was obtained by the reaction of PhSeSiEt(3) with Bu(3)SnH. Although the tributylgermyl phenylselenide instead of PhSeSiMe(3) was treated with tributylstannyl hydride in the presence of a benzaldehyde under radical conditions, hydrogermylated product was not obtained and tributylgermyl hydride was mainly formed.     

Cycloartane glycosides from the rhizomes of Cimicifuga racemosa and their cytotoxic activities

Phytochemical analysis of the rhizomes of Cimicifuga racemosa (Ranunculaceae) resulted in the isolation of twelve cycloartane glycosides (1--12), including four new ones (4--6, 12). The structures of the new compounds were determined by spectroscopic analysis, including two-dimensional (2D) NMR data, and chemical methods. The isolated compounds were evaluated for their cytotoxic activities against human oral squamous cell carcinoma (HSC-2) cells and normal human gingival fibroblasts (HGF).     

On Sylow Subgroups of Abelian Affine Difference Sets

An n-subsetD of a group G of order is called an affine difference set of G relativeto a normal subgroup N of G of order if the list of differences containseach element of G-N exactly once and no elementof N. It is a well-known conjecture that if Dis an affine difference set in an abelian group G,then for every prime p, the Sylow p-subgroupof G is cyclic. In Arasu and Pott [1], it was shownthat the above conjecture is true when . In thispaper we give some conditions under which the Sylow p-subgroupof G is cyclic.     

A new heptacoordinated organogermanium compound; trichlorogermyl[tris(2-methoxyphenyl)]methane

A new hypercoordinated organogermanium compound, trichlorogermyl[tris(2-methoxyphenyl)]methane (4) was prepared, and its tricapped tetrahedral structure was confirmed by X-ray crystallographic analysis. All interatomic oxygen?germanium distances are shorter than the sum of van der Waals radii of O and Ge (3.62 Å).     

Intermetallic phase formation in electrochemical alloy deposition

Three examples of the electrochemical deposition of intermetallic phases are shown. Electrodeposition of the single-phase -brass superlattice at underpotentials of Zn in Cu-Zn alloy plating is explained by an accumulative underpotential deposition (UPD) mechanism. Growth of the Cu-Sn intermetallic phase layer in the contact immersion deposition of Sn onto Cu is accounted for by a UPD/vertical solid-state diffusion mechanism. Ag₃Sn formation in the Sn/Ag-nanoparticle composite plating is illustrated by atomic site exchange at the interface between the deposited Sn matrix and the occluded Ag nanoparticles.