Conformational analysis of ethylene oxide and ethylene imine oligomers by quantum chemical calculations: solvent effects

Summary  Conformational analyses using quantum chemical calculations were carried out for 1- to 4-mers of ethylene oxide (EO) and ethylene imine (EI) oligomer models (EO-x and EI-x, x = 1 - 4) in the liquid phase using four solvents (permittivity: ε = 2.0 ~80.1). The results were compared against those obtained in the gaseous phase. The calculations involved either RHF/6-31+G(d,p) or B3LYP/6-31G(d) // SCRF/IPCM, based on the observed and calculated results for the energy difference between trans- and cis-dichloroethane. The conformations repeated for a unit of X-C, C-C and C-X bonds (X: O or N) were examined. For both oligomers, the energies of every conformer decreased with increasing ε values, and were linear against the Kirkwood function (K_f = (ε-1)/(2ε+1)). For the EO oligomers, the (ttt)_x conformer was most stable in the gaseous phase. In liquid phases, however, the preference for the gauche-conformation (gauche preference) of the C-C bonds increased with higher values of ε. In the case of EO-3, the (tg⁺t)_x conformer was most stable above an ε value of 8.9, which were in good agreement with those observed for triglyme solutions using NMR analysis. For the EI oligomers, the (tg⁺t)_x conformer was most stable in either gaseous or liquid phase, and the gauche preference of the C-C bonds in both phases were comparable. These results were in good agreement with those observed for di-MEDA solutions using NMR analysis. It was estimated that such small solvent effects on gauche preferences of the EI oligomers result in weakening for hydrogen bonds (NH-N) of neighboring imino groups by solvents.     

Determination and confirmation of five phenolic antioxidants in foods by LC/MS and GC/MS

Identification and determination of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), nordihydroguaiaretic acid (NDGA), propyl gallate (PG) and tert-butylhydroquinone (TBHQ) by means of LC/MS and GC/MS were examined. These five phenolic antioxidants were detected as their pseudo-molecular ions [M-H]- by LC/MS using a Shim-pack FC-ODS column with drying gas. Moreover, BHA, BHT and TBHQ were detected based on their mass fragment ions by GC/MS. Decomposition of TBHQ, NDGA and PG during analysis could be prevented by the addition of L-ascorbic acid (AsA) to the extraction solvent. All five antioxidants were extracted from nikuman, olive oils, peanut butter, pasta sauce and chewing gum with a mixture of acetonitrile-2-propanol-ethanol (2:1:1) containing 0.1% AsA (AsA mixture), which had been cooled in a freezer and filtered. One part filtrate and 5 parts water were mixed and placed on a Mega-Bond Elut C18 cartridge, except in the case of chewing gum. Lipids in foods were removed on a C18 cartridge by washing with 5 mL of 5% acetic acid, and antioxidants were eluted with 5 mL of AsA mixture. The antioxidants spiked into nikuman, olive oil, peanut butter, pasta sauce and chewing gum were successfully identified and their concentrations determined by LC/MS, and GC/MS with good recoveries.     

Template-free synthesis and adsorption properties of microporous crystal AlPO4-H3

A microporous aluminophosphate molecular sieve, AlPO₄-H3, was prepared without using organic templates. It was crystallized at temperatures as low as 90 °C from aluminophosphate gels with a molar ratio of Al₂O₃/P₂O₅1; the addition of seed crystals was essential. AlPO₄-H3 was topotactically and irreversibly converted into AlPO₄-D at 300 °C, which adsorbed water up to 0.2 ml/g at 25 °C, although nitrogen gas was hardly adsorbed at liquid nitrogen temperature.     

Divergent consequences of success and failure in Japan and North America: An investigation of self-improving motivations and malleable selves.

Self-enhancing and self-improving motivations were investigated across cultures. Replicating past research, North Americans who failed on a task persisted less on a follow-up task than those who succeeded. In contrast, Japanese who failed persisted more than those who succeeded. The Japanese pattern is evidence for a self-improving orientation: Failures highlight where corrective efforts are needed. Japanese who failed also enhanced the importance and the diagnosticity of the task compared with those who succeeded, whereas North Americans did the opposite. Study 2 revealed that self-improving motivations are specific to the tasks on which one receives feedback. Study 3 unpackaged the cultural differences by demonstrating that they are due, at least in part, to divergent lay theories regarding the utility of effort. Study 4 addressed the problem of comparing cultures on subjective Likert scales and replicated the findings with a different measure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implementation of self-healing function in ATM networks

This paper proposes an implementation scheme for the self-healing function in ATM (Asynchronous Transfer Mode) networks and assesses its performance in a developed experimental system. First, our proposed ATM self-healing scheme is described. This scheme realizes more rapid restoration of failed Virtual Paths than other self-healing algorithms, supports the node failure case, and minimizes the spare resources required. Next, an implementation scheme is proposed. We propose that the self-healing function can be implemented as a software process, and that OAM (Operation, Administration, and Maintenance) cells be utilized for fast message transmission. Next, results of a prototype system that we implemented on an ATM cross-connect system are discussed. The fundamental characteristics of restoration performance are measured using the experimental system. Based on these results, restoration characteristics of real world scale networks are estimated by computer simulations. The simulation results indicate that any-one link failure is completely restored within 2 seconds.     

Preparation of nm-sized BaO3 particles using a new 2-step thermal decomposition of barium titanyl oxalate

To obtain inpurity-free and nm-sized barium titanate (BaTiO₃) particles, a new 2-step thermal decomposition method from barium titanyl oxalates (BaTiO(C₂O₄)₂ · 4H₂O) was proposed. At the 1st step, BaTiO(C₂O₄)₂ · 4H₂O was annealed at 400°C for 1 h in the O₂ flow. The annealing temperature of 400°C was chosen for the following reasons; (1) no formation of BaCO₃ and TiO₂ and (2) the complete removal of H₂O and other carbon species. This compound obtained at 400°C was amorphous phase, and its chemical composition was BaCO₃-TiO₂. When this compound was annealed in air at higher temperatures, the large BaTiO₃ particles were prepared with by-products such as BaCO₃. Thus, at the 2nd step, to prevent the crystal growth and the formation of BaCO₃, this compound was annealed above 600°C in vacuum. Finally, the BaTiO₃ single crystals with a size with 16.5 nm were prepared around 620°C. These BaTiO₃ fine particles were characterized using various methods to investigate defects and impurities in the particles. As a result, it was confirmed that there was no impurity in the BaTiO₃ lattices.     

Sequence distribution of polyisoprenes

The ¹³C n.m.r. spectra of hydrogenated polyisoprenes were investigated. Polyisoprenes were prepared with n-BuLiEt₂O, Ti(OBu)₄AlEt₃, Col₂ROHPhMgBr, Alfin, and radical catalysts. These polymer were hydrogenated with p-toluenesulphonylhydrazide. ¹³C n.m.r. signals were assigned for triad sequences of

arising respectively from 1,4- and 3,4-units. Signals due to head-to-head and tail-to-tail linkages of 1,4- and 3,4-units were also assigned. It is disclosed that 1,4- and 3,4-units were randomly distributed in n-BuLiEt₂O, Col₂ROHPhMgBr, and radical catalysed polyisoprenes, rather alternating in Ti(OBu)₄AlEt₃ catalysed polyisoprene, and slightly in blocks in Alfin polyisoprene. It is also confirmed that Alfin, radical, and cobalt catalysed polyisoprenes contained significant amounts of head-to-head and tail-to-tail linkages of 1,4- and 3,4- units. Signals due to the tacticity of the polyads of 3,4-units were also discussed.     

Synthesis and viscoelastic properties of new thermosetting resins having isocyanurate and oxazolidone rings in their molecular structures

A new type of thermosetting resin can be obtained from solventless varnishes composed of polyfunctional isocyanates and epoxides. The IR spectra show that the cured resins have isocyanurate and oxazolidone rings in their chemical structure, hence their name, isocyanurate–oxazolidone resins. The viscoelastic behavior of the cured resins can be varied considerably by selecting an appropriate reactant species and changing the equivalent ratio of the isocyanate and epoxy groups in the varnishes. Three relaxations, labeled α, β, and γ, characterize their dynamic mechanical spectra. The α-dispersion is due to the glass transition, the β-dispersion, to local mode motions of the backbone chains of resins, and the γ-dispersion, to the molecular motions of long alkyl chains. If certain additives are mixed into the varnishes before curing, microphase separation takes place during the reactions. The resins finally obtained have a peculiar physical structure in which rubber particles are dispersed throughout a matrix phase as confirmed by scanning electron-microscopic analysis and viscoelastic behavior.     

Characterization of Nonlinear Transmission Lines for Short Pulse Amplification

Pulse propagation on nonlinear transmission lines (NLTLs), which are transmission lines with regularly spaced Schottky varactors, is investigated for the amplification of short pulses. We recently found that the soliton developed in an NLTL experiences an exponential amplitude growth, when it couples with an existing voltage edge. This paper clarifies how the pulse gain depends on the device parameters, including the line inductance, capacitance, and gradient of voltage edge, and describes the design criteria of an NLTL as a pulse amplifier, together with several results of calculations that examine the potential of the NLTL.