Chiral N-phosphonyl imine chemistry: asymmetric additions of glycine enolate to diphenyl diamine-based phosphonyl imines

Diphenyl diamine-based phosphonyl imines attached by the N-isopropyl group in the auxiliary have been synthesized in good yields under convenient reaction conditions. These new chiral N-phosphonyl imines can react with glycine enolate smoothly to give chiral α-β diamino esters in good yields (72%–90%) and up to excellent diastereoselectivity (>99:1 dr). By treatment with HBr, the chiral auxiliary can be readily removed. The absolute structure has been unambiguously determined by converting a product to a known sample.     

Reticular Sn nanoparticle-dispersed PAN-based carbon nanofibers for anode material in rechargeable lithium-ion batteries

Reticular tin nanoparticle-dispersed carbon (Sn/C) nanofibers were fabricated by stabilization of electrospun SnCl₄/PAN composite fibers and subsequent carbonization at different temperatures. These Sn/C composite nanofibers used as anode materials for rechargeable lithium-ion batteries (LIBs) show that the Sn/C nanofibers at 700 and 850 °C present much higher charge (785.8 and 811 mA h g^?1) and discharge (1211.7 and 993 mA h g^?1) capacities than those at 550 and 1000 °C and the as-received CNFs at 850 °C, corresponding to coulombic efficiencies of 64.9% and 81.7%, respectively. The superior electrochemical properties of the intriguing Sn/C nanofibers indicate a promising application in high performance Li-ion batteries.     

Dissipative particle dynamic simulation study of lipid membrane

The lipid membrane plays crucial roles in countless biologic processes, ranging from cell motility, endo- and exocytosis, and cell division to protein aggregation and trafficking. To gain a molecular insight in these biologic processes, the recently developed mesoscale simulation technique, dissipative particle dynamics (DPD) simulation, has become an invaluable tool. By providing a brief survey of existing atomistic and popular coarse-grained models used today in studying the dynamics (including vesicle formation and (protein-mediated) vesicle fusion) and phase behavior of lipid bilayers, this review illustrates how mesoscopic DPD models can be used to obtain a better understanding of these biologic processes currently inaccessible to atomistic and most coarse-grained models.     

Cd13−xInySb10 (x≈2.7, y≈1.5): An Interstitial‐Free Variant of Thermoelectric β‐Zn4Sb3

Although free from structural disorder , the new intermetallic compound Cd_13?xIn_ySb₁₀ (see figure) displays similarly low thermal conductivity values as disordered thermoelectric β‐Zn₄Sb₃ with an isostructural framework.

     

Performance improvement of electrochromic display devices employing micro-size precipitates of tungsten oxide

In this paper, we studied the effect of micro-size WO₃ precipitates on the electrochromic characteristics based on aging test. The electrochromic mechanism can be effectively investigated by a solid-state TaN/WO₃/ITO capacitor. The experimental results reveal that WO₃ electrochromic devices with optimized aging time of 4 days exhibit a higher optical contrast and longer retention time, which is mainly attributed to the formation of micro-size WO₃ precipitates during aging process. The performance improvement using micro-size WO₃ precipitates has the potential in future large-area window or energy efficient display applications.     

DNA Degradation of Genetically Modified Cottonseed Meal During Feed Processing

The effects of dry heating, wet heating, and extrusion on the degradation of DNA in cottonseed meal (CSM) were studied using polymerase chain reaction (PCR) and real-time PCR approach. Both the sad1 DNA, ranging between 128 and 883 bp in size, and the cry1Ab/c gene, ranging between 183 and 652 bp in size, were detectable in all dry-heated CSM and cottonseed. During wet heating, the sad1 gene (≥883 bp) and the cry1Ab/c (≥952 bp) gene were thoroughly degraded at 105 and 120 °C, respectively. Sizes from 128 to 530 bp for the sad1 gene and sizes from 183 to 652 bp for the cry1Ab/c gene were detected during extrusion at temperatures ranging from 75 to 135 °C. Fragments ≤883 bp for the sad1 gene and ≤952 bp for the cry1Ab/c gene were detected in all of the extruded samples with water content varying between 26 and 34 %. The copy number ratio of cry1Ab/c to sad1 in samples of Bt cottonseed meal decreased rapidly when the temperature increased during the heating process. In conclusion, feed processing markedly degrades the larger DNA fragments of sad1 and cry1Ab/c, with high temperature and water content being the main factors for that degradation.     

Alternating copolymers of hexafluoroisobutylene with vinyl trifluoroacetate and vinyl pentafluorobenzoate

Copolymerizations of hexafluoroisobutylene (HFIB) with vinyl pentafluorobenzoate (VPFB) and vinyl trifluoroacetate (VTFA) were carried out in bulk using perfluorodibenzoyl peroxide as the radical initiator. The copolymers obtained were characterized by proton and fluorine NMR spectroscopy. The monomer reactivity ratios in the polymerization of HFIB with VPFB were r₁ (HFIB) = 0, r₂ (VPFB) = 0.373, and r₁r₂ = 0. The results indicated that these copolymers have alternating structures. Similarly, the copolymers of HFIB and VTFA also showed alternating structures. The films of HFIB‐co‐VPFB were prepared by casting THF solution of polymers. Films obtained were flexible and transparent. The refractive indices of copolymers were 1.4549, 1.4490, and 1.4438 at 532, 633, and 839 nm, respectively. The average T_gs of HFIB‐co‐VTFA and HFIB‐co‐VPFB were 52 and 71 °C, respectively. From these results, the T_g of the hypothetical HFIB homopolymer is postulated to be in between 70 and 90 °C, which may be useful in the assessment of T_gs of HFIB copolymers with other vinyl monomers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Physical,hydrochemical and isotopic characteristics of springs in Beijing,China, compared to historical properties

A physical, hydrochemical and isotopic evaluation of springs in Beijing was conducted in 2009 to reveal apparent changes in the properties of those springs. The results showed that most of the 2nd class springs and more than 50 % of the 1st class springs recorded in the early 1980s were depleted, while the discharges of existing springs have also decreased sharply. In addition, the majority of springs were of the HCO₃–Ca–Mg type and good water quality, with the quality indices changing slightly compared to those recorded 30 years ago. The abundances of ²H, ¹⁸O, and ³H in the springs indicated that most of the springs were of meteoric origin with a relatively close connection to modern atmospheric precipitation. As a result, the springs have a relatively strong renewability within a shallow circulation.     

Complex dynamic behavior in a viral model with state feedback control strategies

With the consideration of mechanism of prevention and control for the spread of viral diseases, in this paper, we propose two novel virus dynamics models where state feedback control strategies are introduced. The first model incorporates the density of infected cells (or free virus) as control threshold value; we analytically show the existence and orbit stability of positive periodic solution. Theoretical results imply that the density of infected cells (or free virus) can be controlled within an adequate level. The other model determines the control strategies by monitoring the density of uninfected cells when it reaches a risk threshold value. We analytically prove the existence and orbit stability of semi-trivial periodic solution, which show that the viral disease dies out. Numerical simulations are carried out to illustrate the main results.     

Synthesis,structural characterization and catalytic activity of benzimidazole‐functionalized Pd(II) N‐heterocyclic carbene complexes

Two Pd(II)–NHC complexes bearing benzimidazole and pyridine groups have been successfully prepared and fully characterized by NMR and X‐ray diffraction analysis. The structure of palladium complexes are a typical square‐planar with palladium surrounded by two pairs of trans‐arranged benzimidazole and carbene ligands. The Pd–NHC complexes have been proved to be a highly efficient catalyst for the Mizoroki–Heck coupling reaction of aryl halides with various substituted acrylates under mild conditions in excellent yields. Copyright © 2013 John Wiley & Sons, Ltd.