A new redox-active coordination polymer with cobalticinium dicarboxylate

A new two-dimensional coordination polymer with cobalticinium 1,1'-dicarboxylate (ccdc) incorporated in the framework has been prepared, the ccdc functioning as unique monoanionic dicarboxylate ligands. The compound shows a high redox activity based on the ccdc units.     

Models and Inference for Corrosion Pit Depth Data

A new regression structure is introduced to several families of distributions, including the Generalized Extreme Value (GEV) distribution, which are available to explain the distribution of the maximum pit depth of a small sample. This regression structure depends on sample sizes, but under a simple assumption it is also available in the case of unknown sample sizes. GEV with the proposed regression structure provides us with a new extrapolation model for time. Compared to ordinary GEV models, effectiveness of our GEV model is demonstrated for our real data set. Also, comparisons are made with GEV and other two families of distributions with respect to the proposed regression structure.     

Practical asymmetric synthesis of the herbicide (S)-indanofan via lipase-catalyzed kinetic resolution of a diol and stereoselective acid-catalyzed hydrolysis of a chiral epoxide

Racemic indanofan [(+/-)-1] was efficiently converted to enantiopure (S)-indanofan [(S)-1] by a combination of enzymatic resolution and chemical inversion techniques. An additional important technique is the use of an o-xylene complex of a hemiketal (S)-3c as a precursor, which can be quantitatively converted to (S)-indanofan and easily purified by recrystallization from o-xylene.     

Rhodium-catalyzed approach to Mannich-type products using aldimine,alpha,beta-unsaturated ester,and hydrosilane

A rhodium-catalyzed method for the synthesis of beta-amino esters was accomplished in a one-pot procedure from aldimine, alpha,beta-unsaturated ester and hydrosilane.     

Re-revision of the stereo structure of piperidine lactone,an intermediate in the synthesis of febrifugine

The stereo structure of piperidine lactone (3), an intermediate of the antimalarial agent febrifugine ((+)-1) prepared by a synthetic method, was re-revised to the cis-form from the trans-form.     

The effect of various substances on the suppression of the bitterness of quinine-human gustatory sensation,binding, and taste sensor studies

The purpose of this study was to quantify the degree of suppression of the perceived bitterness of quinine by various substances and to examine the mechanism of bitterness suppression. The following compounds were tested for their ability to suppress bitterness: sucrose, a natural sweetener; aspartame, a noncaloric sweetener; sodium chloride (NaCl) as the electrolyte; phosphatidic acid, a commercial bitterness suppression agent; and tannic acid, a component of green tea. These substances were examined in a gustatory sensation test in human volunteers, a binding study, and using an artificial taste sensor. Sucrose, aspartame, and NaCl were effective in suppressing bitterness, although at comparatively high concentrations. An almost 80% inhibition of bitterness (calculated as concentration %) of a 0.1 mM quinine hydrochloride solution required 800 mM of sucrose, 8 mM of aspartame, and 300 mM NaCl. Similar levels of bitterness inhibition by phosphatidic acid and tannic acid (81.7, 61.0%, respectively) were obtained at much lower concentrations (1.0 (w/v)% for phosphatidic acid and 0.05 (w/v)% for tannic acid). The mechanism of the bitterness-depressing effect of phosphatidic acid and tannic acid was investigated in terms of adsorption and masking at the receptor site. With phosphatidic acid, 36.1% of the bitterness-depressing effect was found to be due to adsorption, while 45.6% was due to suppression at the receptor site. In the case of 0.05 (w/v)% tannic acid, the total bitterness-masking effect was 61.0%. The contribution of the adsorption effect was about 27.5% while the residual masking effect at the receptor site was almost 33%. Further addition of tannic acid (0.15 (w/v)%), however, increased the bitterness score of quinine, which probably represents an effect of the astringency of tannic acid itself. Finally, an artificial taste sensor was used to evaluate or predict the bitterness-depressing effect. The sensor output profile was shown to reflect the depressant effect at the receptor site rather well. Therefore, the taste sensor is potentially useful for predicting the effectiveness of bitterness-depressant substances.     

Synthesis of novel phosphinic acid-containing polymers

Three arylene difluoride monomers containing phosphine oxide ( 1 ), phosphinic acid ( 2 ), or phosphinate ester ( 3 ) groups were prepared and polymerized with bisphenol A to give novel poly-(arylene ether)s ( 4 , 5 , and 6 ). The polymers obtained had moderate molecular weights (η_inh: 0.14–0.30 dL g⁻¹ in N-methylpyrrolidinone) and glass-transition temperatures (T_g: 102–200 °C), depending on the phosphine group in the main chain. Using bis(4-fluorophenyl)sulfone as a comonomer improved the polymerization to give copolymers with higher solution viscosities. The stoichiometric investigation revealed that 7 mol % excess of fluoride monomer gave the highest molecular weight copolymer 8 with η_inh of 0.78 dL g⁻¹, which had a T_g of 176 °C, a T of 432 °C, and formed a hard film by casting from solution. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1854–1859, 2001     

Strain energy function of an uncross-linked butadiene rubber estimated from planar extension

The derivatives of the strain energy function u with respect to the invariants of the strain tensor (I₁ and I₂) are estimated for uncross-linked butadiene rubber by using the BKZ constitutive equation. The derivatives at small deformations show anomalous behavior; namely, an upturn for ∂u/∂I₁ and a downturn for ∂u/∂I₂ take place, as is the case of cross-linked rubbers. At large deformations, u is well described by u = A₁(I₁ −3) + A₂(I₂ −3) with numerical constants A₁ and A₂. This behavior is also quite similar to that for cross-linked rubbers. The non-zero positive constant A₂ for the melt suggests that the non-zero value is due to neither the inhomogeneity in network structure nor high extension of constituent polymer chains.