Ray class invariants over imaginary quadratic fields

Let $K$ be an imaginary quadratic field of discriminant less than or equal to -7 and $K_{(N)}$ be its ray class field modulo $N$ for an integer $N$ greater than 1. We prove that singular values of certain Siegel functions generate $K_{(N)}$ over $K$ by extending the idea of our previous work. These generators are not only the simplest ones conjectured by Schertz, but also quite useful in the matter of computation of class polynomials. We indeed give an algorithm to find all conjugates of such generators by virtue of Gee and Stevenhagen

Adaptive Changes of Some Enzyme Activities in Rats and Humans to Dietary Protein

A study of the adaptive changes of some enzyme activities to the dietary protein intake was made in the liver, kidney, and pancreas of rats and serum of humans. The rats fed the 40 per cent casein diet had a higher rate of weight gain and the weights of the liver and kidney were higher than in the rats fed the 10 per cent casein diet. Three enzymes involved in the elimination of excess nitrogen from the body were found to show a similar response to increased dietary protein intake. These enzymes were: D-amino acid oxidase in the kidneys, arginase in the liver and kidneys, and glutamic-pyruvic transaminase in the liver of rats. The rate of enzyme induction was detectable the second day, being high during the first four days and reaching the maximum value on the fourth day. Thereafter, the enzymatic activity did not change much. The alkaline phosphatase activities in the liver and kidneys of the rats did not show significant change during consumption of the diets containing 10 per cent or 40 per cent casein. Samples of pancreatic trypsinogen and chymotrypsinogen of the rats were not collected during the appropriate time to note any significant changes caused by the diets . A more appropriate experimental design, including proper timing for feedings and dissections, for the study of the adaptation of the proteolytic enzymes in the pancreas of the rats is desirable and recommended. The values for the circulating enzymes of the human serum, 0-amino acid oxidase, glutamic-pyruvic transaminase, and alkaline phosphatase were not found to be affected significantly by the diets containing 12 per cent and 30 per cent protein calories

Au-SN Flip-Chip Solder Bump for Microelectronic and Optoelectronic Applications

As an alternative to the time-consuming solder pre-forms and pastes currently used, a co-electroplating method of eutectic Au-Sn alloy was used in this study. Using a co-electroplating process, it was possible to plate the Au-Sn solder directly onto a wafer at or near the eutectic composition from a single solution. Two distinct phases, Au5Sn and AuSn, were deposited at a composition of 30at.%Sn. The Au-Sn flip-chip joints were formed at 300 and 400 degrees without using any flux. In the case where the samples were reflowed at 300 degrees, only an (Au,Ni)3Sn2 IMC layer formed at the interface between the Au-Sn solder and Ni UBM. On the other hand, two IMC layers, (Au,Ni)3Sn2 and (Au,Ni)3Sn, were found at the interfaces of the samples reflowed at 400 degrees. As the reflow time increased, the thickness of the (Au,Ni)3Sn2 and (Au,Ni)3Sn IMC layers formed at the interface increased and the eutectic lamellae in the bulk solder coarsened.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Experimental Evidence for a Metallohydrolase Mechanism in Which the Nucleophile Is Not Delivered by a Metal Ion: EPR Spectrokinetic and Structural Studies of Aminopeptidase from \u3cem\u3eVibrio proteolyticus\u3c/em\u3e

Metallohydrolases catalyse some of the most important reactions in biology and are targets for numerous chemotherapeutic agents designed to combat bacterial infectivity, antibiotic resistance, HIV infectivity, tumour growth, angiogenesis and immune disorders. Rational design of inhibitors of these enzymes with chemotherapeutic potential relies on detailed knowledge of the catalytic mechanism. The roles of the catalytic transition ions in these enzymes have long been assumed to include the activation and delivery of a nucleophilic hydroxy moiety. In the present study, catalytic intermediates in the hydrolysis of L-leucyl-L-leucyl-L-leucine by Vibrio proteolyticus aminopeptidase were characterized in spectrokinetic and structural studies. Rapid-freeze-quench EPR studies of reaction products of L-leucyl-L-leucyl-L-leucine and Co(II)-substituted aminopeptidase, and comparison of the EPR data with those from structurally characterized complexes of aminopeptidase with inhibitors, indicated the formation of a catalytically competent post-Michaelis pre-transition state intermediate with a structure analogous to that of the inhibited complex with bestatin. The X-ray crystal structure of an aminopeptidase–L-leucyl-L-leucyl-L-leucine complex was also analogous to that of the bestatin complex. In these structures, no water/hydroxy group was observed bound to the essential metal ion. However, a water/hydroxy group was clearly identified that was bound to the metal-ligating oxygen atom of Glu152. This water/hydroxy group is proposed as a candidate for the active nucleophile in a novel metallohydrolase mechanism that shares features of the catalytic mechanisms of aspartic proteases and of B2 metallo-b-lactamases. Preliminary studies on site-directed variants are consistent with the proposal. Other features of the structure suggest roles for the dinuclear centre in geometrically and electrophilically activating the substrate