The role of Alx-4 in the establishment of anteroposterior polarity during vertebrate limb development

We have determined that Strong's Luxoid (lstJ) [corrected] mice have a 16 bp deletion in the homeobox region of the Alx-4 gene. This deletion, which leads to a frame shift and a truncation of the Alx-4 protein, could cause the polydactyly phenotype observed in lstJ [corrected] mice. We have cloned the chick homologue of Alx-4 and investigated its expression during limb outgrowth. Chick Alx-4 displays an expression pattern complementary to that of shh, a mediator of polarizing activity in the limb bud. Local application of Sonic hedgehog (Shh) and Fibroblast Growth Factor (FGF), in addition to ectodermal apical ridge removal experiments suggest the existence of a negative feedback loop between Alx-4 and Shh during limb outgrowth. Analysis of polydactylous mutants indicate that the interaction between Alx-4 and Shh is independent of Gli3, a negative regulator of Shh in the limb. Our data suggest the existence of a negative feedback loop between Alx-4 and Shh during vertebrate limb outgrowth.     

An analysis of creep crack propagation on the basis of the plastic singular stress field

In order to gain an insight into creep crack propagation problems a mechanics approach is presented in this paper on the basis of the plastic singular stress field near a crack tip under the Mode III and I steady-state creep conditions, in combination with a generalized creep damage hypothesis. Closed form equations which predict rates of creep crack propagation are obtained analytically. According to this analysis, it is found that $\text{b}{}_1\text{(n + 1)}$ is the index which characterizes the effect of damage accumulation in front of a crack, where n is the creep exponent and b₁ is the exponent involved in the creep damage hypothesis used in this analysis. The tendency of the predicted crack propagation behaviors is consistent with experimental data available in the literature.     

The potential distribution in local cells on corroding metals

In the galvanic corrosion, the distribution of potential within the electrolyte was calculated for the condition that each local cell is independent and there is no interaction between the local cells. This analysis on the problem extended the Waber's treatment, and the distribution of potential was obtained for each local cell.     

Electrochemical and spectroscopic studies of molybdenum(VI) complexes with aminopolycarboxylic acids

The complexes of molybdenum(VI) with iminodiacetic acid (IDA), nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA) were investigated by means of polarographic and spectroscopic methods. The composition of the complexes was determined by the Job's method as following: 1Mo(VI)/1IDA; 1Mo(VI)/1NTA and 2Mo(VI)/1EDTA. The polarographic wave height was fairly dependent on the nature of the complexes. The overall reaction rate for the reduction of Mo(VI)-IDA complex was limited by diffusion. On the other hand, the polarographic reduction of Mo(VI)-NTA and - EDTA complexes were kinetically controlled by the preceding chemical reaction which was composed of protonation, dimerization and substitution of ligands, however, the rate-determining step was the substitution of ligands. The mechanism for the electroreduction of each complex was discussed.     

Solanesyl pyrophosphate synthetase from Micrococcus lysodeikticus

Solanesyl pyrophosphate synthetase from extracts of Micrococcus lysodeikticus was purified by DEAE-Sephadex, hydroxylapatite, and Sephadex G-100 chromatography. This enzyme was found to catalyze the trans condensation of isopentenyl pyrophosphate with geranyl pyrophosphate to afford all-trans-octaprenyl (C40) and alltrans-nonaprenyl (C45) pyrophosphate without accumulation of prenyl pyrophosphate with chain length shorter than C40. all-trans-Farnesyl and all-trans-geranylgeranyl pyrophosphate also were active as cosubstrates, though they were less effective than geranyl pyrophosphate. However, neither dimethylallyl nor cis,trans,trans-geranylgeranyl pyrophosphate was active. The molecular weight of this enzyme was estimated to be 78 000 by Sephadex G-100 filtration. An enzyme preparation from young shoots of potato was found to hydrolyze the polyprenyl pyrophosphates effectively to give the corresponding prenols.     

Development of Molecular Sieves‐Supported Palladium Catalyst and Chemoselective Hydrogenation of Unsaturated Bonds in the Presence of Nitro Groups

The chemoselective hydrogenation of unsaturated bonds and azide functionalities is achieved in the presence of nitro groups by a heterogeneous palladium catalyst supported on molecular sieves (MS3A). The present method shows a wide‐range of applicability with regard to substrates and the catalyst can be easily prepared and reused at least three times without any loss of activity.     

Potential Oscillations of a Stainless Steel Electrode during Galvanostatic Polarization in a Mixed Solution of Sulfuric and Chromic Acids

Potential oscillations of a stainless steel electrode galvanostatically anodized have been observed in amixture of chromic and sulfuric acids. The potential regularly oscillated between 1.6 V vs. SCE (lower) and 2.1V(upper) with a certain frequency. The potential values are affected neither by the composition of chromic and sulfu-ric acids nor by the magnitude of applied current density although the potential frequency is very sensitive to theseparameters. This phenomenon is interpreted in terms of the repeated formation and disappearance of the saturatedlayer of dichromate ions on the electrode surface. Such scheme is consistent with the in situ FTIR spectroscopicresult that the concentration of Cr2O ions on the electrode surface increased with time during the polarization atthe lower potential but the change in concenetion of Cr2O ions was negligible at the higher potential.