Synthesis and characterization of p-phenylenediamine derivatives bearing an electron-acceptor unit

[reaction: see text] Two series of aniline oligomers bearing fused heterocycles as an electron-acceptor unit were synthesized. They consist of aniline or its derivatives as an electron donor and benzothiadiazole (BT) or quinoxaline (QX) as an electron-acceptor unit. Benzothiadiazoles 1-3 were synthesized by palladium-catalyzed amination. Quinoxalines 4-6 were prepared by palladium-catalyzed amination or transformation from the benzothiadiazoles. These compounds showed a HOMO-LUMO gap smaller than those of their analogues such as thiophene-substituted BT/QXs. Cyclic voltammetry revealed that the electrochemical behavior is dependent on the position of the acceptor heterocycle. Chemical oxidation with Ag2O afforded the corresponding 1,4-quinonediimine derivatives as an E,E-isomer, stereoselectively. As for the BT pentamer analogues 2 and 3, the first oxidation selectively occurred at the amino group adjacent to the benzothiadiazole unit, giving the regiospecific half-oxidized derivatives. Furthermore, the fully oxidized derivative 24 was isolated and characterized.     

Glycoconjugated polymer. I. Synthesis and characterization of amphiphilic polystyrenes with glucose,maltose, and maltohexaose as hydrophilic segments

Glucosyl styrene ( 1a ), maltosyl styrene ( 1b ), and maltohexaosyl styrene ( 1c ) were prepared by the glycosylation of 4‐vinylbenzyl alcohol with the corresponding glycosyl trichloroacetimidates with boron trifluoride diethyl ether complex. The copolymerizations of 1a – 1c with styrene were carried out with 2,2′‐azobis(2‐methylpropionitrile) as an initiator in dry N,N‐dimethylformamide at 60 °C, and this was followed by deacetylation to produce amphiphilic polystyrenes with glucose ( 3a ), maltose ( 3b ), and maltohexaose ( 3c ) as hydrophilic segments. 3 showed various solubility characteristics that were dependent on the content of glucose residues, especially within a range of 20–50 wt %. The solubility characteristics of 3 , related to the copolymer composition, indicated that the hydrophilic property was remarkably improved with an increased number of glucose units, that is, in the order 3a < 3b ? 3c . The results described in this article provide useful information for the design of glycoconjugated architectures with desired amphiphilic properties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4061–4067, 2001     

Regioselective intramolecular [3+2] annulation of allene-nitrones

The regioselective intramolecular 1,3-dipolar cycloaddition of the phenylsulfonylallene-nitrone derivatives has been developed. This reaction showed that the distal double bond of the allene exclusively reacted with the nitrone group to produce the bicyclic isoxazolidine derivatives regardless of the substitution pattern on the allenyl moiety.     

Quantitative SNP genotyping by affinity capillary electrophoresis using PEG-oligodeoxyribonucleotide block copolymers with electroosmotic flow

Quantitative SNP detection was demonstrated with an ACE using a PEG-oligodeoxyribonucleotide block copolymer (PEG-b-ODN) as a probe in the presence of an EOF. The probe's PEG segment with large molecular weight and small polydispersity yielded a high resolution in the separation of a chemically synthesized 60-base ssDNA (WT) and its single-base-substituted mutant (MT). A mixture of WT and MT was clearly separated within 10 min by simultaneously using two types of PEG-b-ODN probes whose ODN segments were complementary to WT and MT and whose PEG segments were of different lengths. The peak area ratio between WT and MT was in good agreement with the feed ratio. The averaged difference between the feed and observed ratio of MT was determined to be 0.23%, which is lower than that of any other methods. The ACE using the PEG-b-ODN probes in the presence of EOF could be utilized as a facile method for estimating SNP allele frequency in various research fields.     

Low bending loss and effectively single-mode all-solid photonic bandgap fiber with an effective area of 650 μm2

A large-mode-area all-solid photonic bandgap fiber with a seven-cell core and five high-index rod rings is investigated. Numerical simulations show that an effective area of more than 500 μm(2), a bending loss of less than 0.1 dB/m at a bending radius of 10 cm and effectively single-mode operation can be achieved simultaneously. A core diameter of 44.8 μm and an effective area of 650 μm(2) at 1064 nm are achieved in a fabricated fiber. Bending loss at 1064 nm is 0.09 dB/m at a bending radius of 7 cm. Effectively single-mode operation is also realized at a bending radius of 10 cm.     

Transient thermal stresses of solid and hollow spheres with spherically isotropic thermoelastic properties

Summary In this paper, we deal with transient thermal stress problems of a spherical region under the condition that the continuum medium possesses spherically isotropic thermoelastic properties. For illustrative purposes, we have analyzed the transient thermal stress problems of solid and hollow spheres. From the numerical calculations it is shown that the thermal stress distributions vary considerably in accordance with the variation of the thermoelastic compliance constants.

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Transiente Wärmespannungen in vollen und hohlen Kugeln mit sphärisch-isotropen thermoelastischen Eigenschaften

Übersicht Es werden transiente Wärmespannungsprobleme in Kugeln behandelt, wobei vorausgesetzt wird, daß das Material sphärisch-isotrope thermoelastische Eigenschaften hat. Zur Illustration werden Voll- und Hohlkugel untersucht. Die numerischen Ergebnisse zeigen, daß die Verteilung der Wärmespannungen sehr stark von den thermoelastischen Konstanten abhängt.

     

Calorimetric study on the electronic structure in UP-US system

The heat capacity of UP_1?xS_x (x = 0.0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0) has been measured from 80 to 670 K by laser-flash calorimetry. All samples exhibit an anomaly corresponding to the magnetic transition. The magnetic transition temperatures determined are in good agreement with literature values. UP_0.4S_0.6 shows an additional small peak at 86 K below T_c. It has been derived that the US-rich ferromagnetically ordered state should be divided into two phases in terms of the direction of the moments. Above 250 K, the heat capacities of all samples increase monotonically with temperature and are well represented in the form of C_p= 6R + AT ? BT^?2. The conduction band structure has been derived from the high-temperature linear term and has been compared with that in literature. It has been suggested that the magnetically ordering behavior such as the direction of the moments would be closely correlated with the band structure.     

Tong-type identity and the mean square of the error term for an extended Selberg class

In 1956, Tong established an asymptotic formula for the mean square of the error term of the summatory function of the Piltz divisor function d3(n). The aim of this paper is to generalize Tong's method to a class of Dirichlet series L(s) which satisfies a functional equation. Let a(n) be an arithmetical function related to a Dirichlet series L(s), and let E(x) be the error term of ′n xa(n). In this paper, after introducing a class of Diriclet series with a general functional equation(which contains the well-known Selberg class), we establish a Tong-type identity and a Tong-type truncated formula for the error term of the Riesz mean of the coefficients of this Dirichlet series L(s). This kind of Tong-type truncated formula could be used to study the mean square of E(x) under a certain assumption. In other words, we reduce the mean square of E(x) to the problem of finding a suitable constant σ*which is related to the mean square estimate of L(s). We shall represent some results of functions in the Selberg class of degrees 2–4.     

The Riemann problem for thermoelastic materials with phase change

We consider the Riemann problem for a system of conservation laws related to a phase transition problem. The system is nonisentropic and we treat the case where the latent heat is not zero. We study the cases where the initial data are given in the same phase and in the different phases. The role of the entropy condition is studied as well as the kinetic relation and the entropy rate admissibility criterion. We confine our attention to the case where the speeds of phase boundaries are close to zero. This is one interesting case in physics. We discuss the number of phase boundaries consistent with the above criteria and the uniqueness and nonuniqueness issue of the solution to the Riemann problem.     

In situ spatial-profile monitoring of beam flux of neutral free radicals produced by photo-deionization of negative ion beams

Ion-current difference measurement by light intensity modulation (ICD) is introduced as a convenient method to characterize a purified beam of momentum-controlled neutral free radicals produced by photo-deionization of a negative ion beam for the purpose of surface-reaction-selective device processing. The ICD setup developed in this study to estimate the number flux of the photo-deionized neutral particles exhibited the high precision, sensitivity, and spatial resolution.