Effects of double photoreactions on polycoumarate photomechanics

We established a polymerization condition of 3‐hydroxycinnamic acid, 3HCA, having photoreactive units over all the main chains. The polymers showed two types of photoreaction, that is, intramolecular E–Z isomerization and interchain [2 + 2] cycloaddition. Spectroscopic studies showed that the rate of the isomerization was higher than that of the cycloaddition. Although the original fiber was very brittle, the short‐time UV‐irradiation made the fiber softer and more elastic because the chain bending by the isomerization preferentially occurred. On the other hand, the long‐time irradiation made the fiber harder because of the cross‐linking by the cycloaddition, and simultaneously enhanced the elasticity. Besides we found that the cast film of P3HCA showed a photo‐bending behavior with the convex surface facing the UV‐lamp by the initial E–Z isomerization. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Various silicon‐containing polymers with Si(H)?CC units

Nine new kinds of thermosetting polymers with the Si(H)? C?C unit were synthesized by dehydrogenative polycondensation reactions between hydrosilanes and diethynyl compounds in the presence of a magnesia catalyst. Phenylsilane, silane, vinylsilane, and n‐octylsilane were used as the hydrosilanes, and 1,3‐diethynylbenzene, 1,4‐diethynylbenzene, 4,4′‐diethynyldiphenyl ether, and 1,3‐diethynyl‐1,1,3,3‐tetramethyldisiloxane were used as the diethynyl compounds. All the polymers were thermosetting, highly heat‐resistant, easily soluble in a solvent, and moldable. In particular, ? Si(R)H? C?C? C₆H₄? C?C? (R = H or CH?CH₂) showed high thermal stability; the temperature of 5% weight loss was greater than 800 °C, and the residue at 1000 °C was over 90%. The thermal stabilities of the polymers were attributed to the crosslinking reaction of the Si? H and C?C bonds. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2658–2669, 2001     

Comparison between simulated and experimental emission spectra of photoionizing nitrogen plasma

A computational model has been developed to provide a straightforward and rapid tool for the calculation of the ionization and population distributions in photoionizing plasmas. The simulated spectral results from this code are compared with experimental data and are found to be in reasonable agreement for photoionized plasmas created with high intensity short pulse lasers.     

High‐sensitivity simultaneous quantification of tacrolimus and 13‐O‐demethyl tacrolimus in human whole blood using ultra‐performance liquid chromatography coupled to tandem mass spectrometry

Blood concentrations of tacrolimus show large variability among patients and the narrow therapeutic range is related to adverse effects. Therefore, therapeutic drug monitoring is needed for strict management. 13‐O‐Demethyl tacrolimus (13‐O‐DMT) was reported as the major metabolite formed by cytochrome P450 (CYP)3A such as CYP3A5. In previous studies, the best lower limit of quantification (LLOQ) was 0.1 ng/mL for both substances. However, this LLOQ may not be low enough now because the dosage of tacrolimus has decreased in recent years. The purpose of this study was to develop and validate a high‐sensitivity and high‐throughput assay for simultaneous quantification of tacrolimus and 13‐O‐DMT in human whole blood using ultra‐performance liquid chromatography with tandem mass spectrometry (UPLC–MS/MS). Thirty‐five stable kidney transplant recipients receiving tacrolimus were recruited in this study. The calibration curve range was 0.04–40 ng/mL. All calibration samples and quality control samples fulfilled the requirements of the US Food and Drug Administration and the European Medicines Agency guidelines for assay validation. Trough concentrations of tacrolimus and 13‐O‐DMT in 35 stable kidney transplant recipients receiving tacrolimus were within the range of the respective calibration curve. Our novel UPLC–MS/MS method is more sensitive than previous methods for quantification of tacrolimus and 13‐O‐DMT.     

Evaluation of retention time for temperature-programmed gas chromatography by use of a closed-form integral

A closed-form integral for the Arrhenius exponential was obtained by using an approximate relation instead of the usual one in a linear temperature program. The closed-form integral can be applied to predict the retention time very well both for a packed column and for a capillary column, in constant the velocity mode.     

Controlled synthesis of colloidal silver nanoparticles in capillary micro-flow reactor

In this study, using a polytetrafluoroethylene (PTFE) capillary tube as a micro-flow reactor, well-dispersed colloidal silver nanoparticles were controllably synthesized with different flow rates of precursory solution. Scanning transmission electron microscopy images and UV–visible absorbance spectra showed that silver nanoparticles with large size can be prepared with slow flow rate in the PTFE capillary reactor. The effects of tube diameters on the growth of colloidal silver nanoparticles were investigated. Experiment results demonstrated that using tube with small diameter was more propitious for the controllable synthesis of silver nanoparticles with different sizes.

     

Total synthesis of (+)-myxothiazols A and Z

The first synthesis of (+)-myxothiazol A 1 was achieved based on a modified Julia olefination between (3,5R)-dimethoxy-(4R)-methyl-6-oxo-(2E)-hexenamide 3, corresponding to the left side of the final molecule, and 4-(2″-benzothiazolyl)sulfonylmethyl-2′-[(1′″R),6′″-dimethylhepta-(2′″E),(4′″E)-dienyl]-2,4′-bithiazole 6, corresponding to the right side. The synthesis of (+)-myxothiazol Z 2 was also achieved based on modified Julia olefination between (3,5R)-dimethoxy-(4R)-methyl-6-oxo-(2E)-hexenoate 4, corresponding to left side of the final molecule, and (S)-sulfone 6.     

Garsia–Haiman modules for hook partitions and Green polynomials with two variables

We consider Garsia–Haiman modules for the symmetric group, a doubly graded generalization of Springer modules. Our main interest lies in singly graded submodules of a Garsia–Haiman module. We show that these submodules satisfy a certain combinatorial property, and verify that this property is implied by a behavior of Macdonald polynomials at roots of unity.     

Studies of Light Neutron-Excess Systems from Bounds to Continuum

The generalized two-center cluster model, which can handle various single particle configurations in general two center systems, is applied to the light neutron-rich system, ¹²Be = α+α+4N. We discuss the change of the neutrons’ configuration around two α-cores as a variation of an excitation energy. We show that the excess neutrons form various chemical-bonding-like configurations around two α cores in the unbound region above the α decay threshold. The possibility of the α cluster formation in the heavier neutron-excess system, ²⁸Ne, is also discussed.