Bubbling and bistability in two parameter discrete systems

We present a graphical analysis of the mechanisms underlying the occurrences of bubbling sequences and bistability regions in the bifurcation scenario of a special class of one dimensional two parameter maps. The main result of the analysis is that whether it is bubbling or bistability is decided by the sign of the third derivative at the inflection point of the map function.     

Use of phosphate glass detectors for study of curium-242 cluster radioactivity

The effect α particle fluences (3 × 10³−2 × 10¹⁵ cm ⁻²) on properties of the two types of phosphate glass detectors with different compositions was studied. It was shown that the registration properties of glass detectors depended on the α particle fluence, spatial distribution of the α particle paths, and glass type. The critical α particle fluences, above which the detector properties changed, were determined.     

Two Chiral Building Blocks for the Stereocontrolled Synthesis of Anti-and Syn-1,3-Diols

During the last decade, chiral building blocks for 1, 3-diols of various configurations have been synthesized and applied widely in the total synthesis of natural polyene macrolide antibiotics1 and 1(, 25-dihydroxyvitamin D3 analogues2,3. The synthesis of the building block has attracted much interest in recent years. Herein, we report the synthesis of two chiral building blocks 1 and 2 in 8 steps and 7 steps respectively, starting from the readily available and inexpensive D (+)-xylose 3 as o…     

CO_2 Adducts of the Amino and Imino Groups Studied by ~1HNMR and ~(13)CNMR

When isolating 1,4-dideoxy-1,4-imino-D-arabinitol using Dowex 1(2 (OH- form) or CM-Sephadex C-25 (NH4+ form), we found another compound always accompanied with it. It was apparent that the two compounds had similar structures from their 1HNMR and 13CNMR in D2O (Fig. 1). At first, we guessed the two compounds were isomerides. But when acid was added into the solution of the two compounds, the signals for the minor compound disappeared.Figure 1 13CNMR of 1,4-dideoxy-1,4-imino-D-arabin…     

CHEMICAL STRUCTURE DEPENDENCE OF THE INTERNAL ENERGY CONTRIBUTION IN RUBBER ELASTICITY

Conformational elasticity theory recently developed has been used to explore the internal energy contribution tothe elastic force f_e/f as a function of strain for poly(cis-1,4-isoprene) and poly(trans-1, 4-isoprene). Calculated f_e/f values arein good agreement with those obtained experimentally. Results show that behavior of f_e/f is mainly contributed by chemicalstructure, or intramolecular interaction, supporting the experimental observations, and that the internal energy contribution isstrain dependent.     

Stereoselective Synthesis of 2-(4-Hydroxyphenyl)-3-hydroxymethyl-1,4-benzodioxane-6-aldehyde—The Key Intermediate of Sinaiticin

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Complete NMR analysis of oxytocin in phosphate buffer

Complete NMR analysis of oxytocin (OXT) in phosphate buffer was elucidated by one‐dimensional (1D)‐ and two‐dimensional (2D)‐NMR techniques, which involve the assignment of peptide amide NH protons and carbamoyl NH₂ protons. The ¹H? ¹⁵N correlation of seven amide NH protons and three carbamoyl NH₂ protons were also shown by HSQC NMR of OXT without ¹⁵N enrichment. Copyright © 2009 John Wiley & Sons, Ltd.