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We report infrared absorption spectroscopy and second-harmonic generation data for barium strontium titanate (BST) and lead zirconate-titanate (PZT) ceramic films in the 3000-5500 cm[sup -1] region. Second-harmonic generation experiments give temperature dependences in accord with oxygen vacancy cluster theory [S. A. Prosandeev, Sov. Phys. JETP 83, 747 (1996); S. A. Prosandeev, V. S. Vikhnin, and S. Kapphan, Integr. Ferroelectr. 32, 1047 (2001); J. Phys. Condens. Matter 14, 4407 (2002)]. A percolation model of vacancy ordering is discussed. The present work shows that earlier data interpreted as polaron spectra in these films were actually artifacts due to interference in the optical apparatus used [B. Guettler, U. Bismayer, P. Groves, and E. Salje, Semicond. Sci. Technol. 10, 245 (1950]; more recent “polaron” spectra in WO[sub 3] films may also be artifacts [L. Berggren, A. Azens, and G. A. Niklassson, J. Appl. Phys. 90, 1860 (2001)]. Numerical estimates of the polaron mass m**=16 m[sub e] in SrTiO[sub 3] and BST help prove that dielectric data in strontium titanate interpreted as bipolarons [A. Levstik et al., Appl. Phys. Lett. 81, 4046 (2002)] are also artifacts. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A modified method based on in situ chemical reduction was developed to prepare mono-dispersed polystyrene/silver (PS/Ag) composite microspheres. In this approach; mono-dispersed PS microspheres were synthesized through dispersion polymerization using poly-vinylpyrrolidone (PVP) as a dispersant at first. Then, poly-dopamine (PDA) was fabricated to functionally modify the surfaces of PS microspheres. With the addition of [Ag(NH3)2]+ to the PS dispersion, [Ag(NH3)2]+ complex ions were absorbed and reduced to silver nanoparticles on the surfaces of PS-PDA microspheres to form PS/Ag composite microspheres. PVP acted both as a solvent of the metallic precursor and as a reducing agent. PDA also acted both as a chemical protocol to immobilize the silver nanoparticles at the PS surface and as a reducing agent. Therefore, no additional reducing agents were needed. The resulting composite microspheres were characterized by TEM, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), XRD, UV-Vis and surface-enhanced Raman spectroscopy (SERS). The results showed that Ag nanoparticles (NPs) were homogeneously immobilized onto the PS microspheres' surface in the presence of PDA and PVP. PS/Ag composite microspheres were well formed with a uniform and compact shell layer and were adjustable in terms of their optical property. [ABSTRACT FROM AUTHOR]

The highly affinitive and selective binding processes of tetrasulfonated 1,5-dinaphtho-38-crown-10 (14-) and tetrasulfonated 1,5-dinaphtho-32-crown-8 (24-) with pyromellitic diimide and naphthalene diimide derivatives bearing cationic terminal groups (PMDI2+ and NDI2+) are comprehensively investigated in aqueous solution by ¹H NMR and UV/vis experiments, mass spectrometry, microcalorimetric titration, and crystallographic analysis. The binding process of host-guest complexation is thermodynamically driven by the large enthalpic gain and favorable entropic change with the high association constants in the range of 104-106 M-1 order of magnitude. Combined with our previously reported thermodynamic data of ethyl viologen (EV2+), it is found that the exclusively selective binding behaviors originate from the size/shape matching effect, as well as the electrostatic interaction between negatively charged hosts and positively charged guests and aromatic π-stacking interrelation between electron-rich donors and electron-deficient acceptors. [ABSTRACT FROM AUTHOR]

We present a test particle simulation on the injection and acceleration of low-energy suprathermal particles by parallel shocks with a focused transport model. The focused transport equation contains all necessary physics of shock acceleration, but avoids the limitation of diffusive shock acceleration (DSA) that requires a small pitch angle anisotropy. This simulation verifies that the particles with speeds of a fraction of to a few times the shock speed can indeed be directly injected and accelerated into the DSA regime by parallel shocks. At higher energies starting from a few times the shock speed, the energy spectrum of accelerated particles is a power law with the same spectral index as the solution of standard DSA theory, although the particles are highly anisotropic in the upstream region. The intensity, however, is different from that predicted by DSA theory, indicating a different level of injection efficiency. It is found that the shock strength, the injection speed, and the intensity of an electric cross-shock potential (CSP) jump can affect the injection efficiency of the low-energy particles. A stronger shock has a higher injection efficiency. In addition, if the speed of injected particles is above a few times the shock speed, the produced power-law spectrum is consistent with the prediction of standard DSA theory in both its intensity and spectrum index with an injection efficiency of 1. CSP can increase the injection efficiency through direct particle reflection back upstream, but it has little effect on the energetic particle acceleration once the speed of injected particles is beyond a few times the shock speed. This test particle simulation proves that the focused transport theory is an extension of DSA theory with the capability of predicting the efficiency of particle injection [ABSTRACT FROM AUTHOR]

We establish several Lyapunov-type inequalities for quasilinear difference systems, which generalize or improve all related existing ones. Applying these results, we also obtain some lower bounds for the first eigencurve in the generalized spectra. [ABSTRACT FROM AUTHOR]

A novel compound, 4-{1′-hydroxy-1′-mercapto-1′-[1′′-2′′(N→O)-isoquinolyl]}yl-1-benzoic acid ( 1), together with six known compounds, 6-hydroxykaempferol-3- O-β-D-glucopyranoside ( 2), rutin ( 3), quercetin-3- O-β-D-glucopyranoside ( 4), kaempferol-3- O-β-D-glucopyranoside ( 5), cartormin ( 6), hydroxysafflor yellow A ( 7), were isolated by chromatography from the n-BuOH fraction of 50% ethanol extraction of Flos carthami. Their structures were elucidated on the basis of spectral analysis and comparison with published data. Among them, compound 1 was shown to possess a weak protective effect against cerebral ischemic damage in rats. [ABSTRACT FROM AUTHOR]

The structural variations of synthetic zircon (ZrSiO4) single crystals irradiated at room temperature by 280 keV Pb+ ions (with fluences up to 1 × 1015 ions/cm2) were investigated using infrared (IR) spectroscopy. Like metamict zircon whose crystal structure is damaged and amorphized by naturally occurring α-decay events, the Pb+-irradiated zircon crystals show a dramatic decrease in reflectivity. However, no significant decrease in wavenumbers of the stretching vibrations of SiO4 tetrahedra in zircon was detected. The Pb+-implanted zircon exhibits new IR bands, indicating irradiation-induced new vibrations or domains, clusters or phases in addition to SiO2 and ZrO2. IR features consistent with those of Pb silicates (with a divalent state, i.e., Pb2+) are also found in the irradiated sample. This finding implies that some of the radiogenic Pb in natural zircon might not actually reside in the zircon lattice or in ZrSiO4 phases, but form new local domains or clusters. Infrared bands of OH-stretching vibrations were also detected in the irradiated synthetic zircon, which was originally free from OH features prior to the irradiation. These results indicate that H can easily diffuse into the irradiated layer or into irradiated-induced phases to form OH or and hydrous species after the irradiated material is damaged. The type and content of hydrous species vary with irradiation fluences. [ABSTRACT FROM AUTHOR]

Eight new cucurbitane glycosides, kuguaglycosides A–H (1–8, resp.), together with five known analogues, 3β,23-dihydroxycucurbita-5,24-dien-7β-yl β-D-glucopyranoside (9), karaviloside III (10), karaviloside V (11), karaviloside XI (12), and momordicoside K (13), were isolated from the root of Momordica charantiaL. The structures of the new compounds were determined on the basis of spectroscopic and chemical methods. [ABSTRACT FROM AUTHOR]

A new series of receptors were designed and synthesized, and their interactions with anions, such as F-, Cl-, Br-, I-, CH3COO-, HSO-4 , and NO-3 , in DMSO solvent were investigated using UV-Vis absorption spectroscopy. The results showed that hydrogen-bonding complexes were formed between the receptors and the tested anions, such as CH3COO- and F-. It was also found that the selectivity of the receptors for anions could be efficiently tuned by changing the place of the substituent group at the N-phenyl moiety. The recognition mechanism and binding mode are discussed. These findings were expected to be of significance for designing and developing a novel, highly selective receptor for the acetate anion in a strong polar solvent. [ABSTRACT FROM AUTHOR]

The local angular distortions around the impurity Co2+ in CdCl2, CdBr2 and PbI2 are theoretically studied from the perturbation formulas of the electron paramagnetic resonance (EPR) parameters, the g factors g// and g⊥ and the hyperfine structure constants A// and A⊥ for a 3d7 ion in trigonal symmetry. In these formulas, the contributions from the s-orbitals of the ligands, which were often ignored, are taken into account based on the cluster approach. By analyzing the EPR spectra, we find that the impurity-ligand bonding angles β related to the C3 axis in the Co2+ impurity centers are different from the corresponding metal-ligand bonding angles βH in the hosts, characterized by the local angular distortions Δβ (=β-βH). The calculated EPR parameters, especially the anisotropies of the g and A factors for the studied systems based on the local angular distortions Δ β, show reasonable agreement with the observed values. [ABSTRACT FROM AUTHOR]

Functionalized Fe3O4nanoparticles decorated with carboxymethylated chitosan were developed and used as a novel magnetic support for the covalent conjugation of papain, one of the most important industrial proteases. The analyses of transmission electron micrographs (TEM) and X-ray diffraction (XRD) showed that the size and structure of functionalized Fe3O4nanoparticles had no significant changes after conjugation with papain. Magnetic measurement revealed that the resultant papain-conjugated nanoparticles were superparamagnetic with a saturation magnetization of 59.3 emu/g. Analyses of Fourier transform infrared (FTIR) spectroscopy and measurement of potentials confirmed the conjugation of papain with the functionalized Fe3O4nanoparticles. Compared with the native papain, the conjugated papain was found to exhibit enhanced enzyme activity, better tolerance to the variations of medium pH and temperature, and improved storage stability as well as good reusability. Considering that the magnetic separation technique possesses the advantages of rapidity, high efficiency, cost-effectiveness, and lack of negative effect on biological activity, such a bioconjugate system may hold potential applications in food, pharmaceutical, leather, cosmetic, and textile industries. [ABSTRACT FROM AUTHOR]

A novel, clean biological transformation reaction by immobilized Rhodobacter sphaeroides has been developed for the synthesis of zinc sulfide (ZnS) nanoparticles with an average diameter of 8 nm. The nanoparticles were examined by X-ray diffraction, transmission electron microscopy, energy dispersive analyses of X-rays, UV–vis optical absorption and photoluminescence spectra. The average diameter of ZnS nanoparticles varied according to the culture time. [ABSTRACT FROM AUTHOR]

Teeth and bones consist of an apatite-type structure and such biogenic apatites usually occur in nano-crystalline form. Because of the small particle size in biological tissues, local structural details of biogenic apatite have still not been resolved in detail. Comparison of the phonon spectra of enamel apatite with those of inorganically formed apatite was carried out to improve our understanding of the vibrational behavior of biogenic apatite. In situ mid-infrared absorption spectra of dental enamel and geologic fluorapatite were recorded from 300 K to ca. 750 K. Lattice vibration modes were studied at low temperature in the infrared region of 150 to 650 cm[sup-1]. The IR excitations indicate that geologic apatite undergoes heavier thermal changes than enamel apatite at temperatures between 60 K and 300 K. In situ high-temperature IR spectra confirm the different thermal evolution of dental enamel and geologic fluorapatite. The P-O overtones or combinational vibrations and hydrous species of enamel apatite show two different thermal regions below and above 600 K. The thermal behavior in the region below 600 K corresponds to the loss of adsorbed and part of the lattice water, combined with an increase of structural OH groups. In the second thermal region (above 600 K), the similarity of thermal response of dental enamel to that of the geologic apatite from 300 K suggests the existence of a highly ordered system. This result may be explained by the dehydration and atomic rearrangements in the channels of enamel apatite structure below 600 K. [ABSTRACT FROM AUTHOR]

The article presents a study addressing ion beam irradiation versus quenching from a melt. Study shows a substantial evidence which indicates differences between the two types of aperiodic state such as the spectral and structural differences. It is noted that while IR-reflection technique is used, infrared spectroscopy has also shown to be useful in distinguishing differences between the crystalline and aperiodic structures.

Particle spectra directly measured by a plasma or low-energy particle experiment on spacecraft often contain instrumental effects due to a limited field of view or angular resolution. It is because the particle distribution function at low energies is highly anisotropic in the spacecraft frame of reference, in which the measurements are made. In this paper, we present a new mathematical method of transforming the particle spectrum to the solar wind frame of reference, where the particle distribution can be assumed to be nearly isotropic. The transformed particle spectrum allows us to investigate the properties of the solar wind, pickup ions, and suprathermal particles without concern for instrumental effects. We apply the method to the measurements made by the Solar Wind Ion Composition Spectrometer on Ulysses. Our results demonstrate that the transformed spectrum can improve the determination of the solar wind density and temperature from the previously published methods. A brief survey of Ulysses data shows that suprathermal ions in the slow solar wind frequently display a velocity distribution very close to the v−5 power law. [ABSTRACT FROM AUTHOR]

Two stable supramolecular loops (1 and 2) were successfully constructed by the molecular recognition of cucurbit[8]uril (CB[8]) and the homoditopic bispyridinium derivatives (3 and 4). Interestingly, the interconversion of molecular loops and [2]pseudorotaxanes could be reversibly switched under neutral and acidic condition, exhibiting the controlled electrochemical and spectroscopic behaviors. [ABSTRACT FROM AUTHOR]

We produced epitaxial graphene under a moderate pressure of 4 mbar (about 400 Pa) at temperature 1600 °C. Raman spectroscopy and optical microscopy were used to confirm that epitaxial graphene has taken shape continually with slight thickness variations and regularly with a centimeter order of magnitude on 4H-SiC (0001) substrates. Then using X-ray photoelectron spectroscopy and Auger electron spectroscopy, we analyzed the chemical compositions and estimated the layer number of epitaxial graphene. Finally, an atomic force microscope and a scanning force microscope were used to characterize the morphological structure. Our results showed that under 4-mbar pressure, epitaxial graphene could be produced on a SiC substrate with a large area, uniform thickness but a limited morphological property. We hope our work will be of benefit to understanding the formation process of epitaxial graphene on SiC substrate in detail. [ABSTRACT FROM AUTHOR]

Breast cancer is one of the leading cancers of women. Ultrasound is often used for breast cancer diagnosis because it is harmless, portable, and low-cost. However, the segmentation of breast ultrasound (BUS) images is a difficult task due to their low contrast and speckle noise. Neutrosophy studies the origin, nature, and scope of neutralities and their interactions with different ideational spectra. It is a new philosophy to extend fuzzy logic and is the basis of neutrosophic logic, neutrosophic probability theory, neutrosophic set theory, and neutrosophic statistics. In this paper, we employ neutrosophy and develop a fully automatic algorithm for BUS image segmentation. By using neutrosophy, we integrate two conflicting opinions about speckle in ultrasound image: speckle is noise and speckle includes pattern information. The experiments demonstrate that the proposed approach is accurate, effective, and robust. [ABSTRACT FROM AUTHOR]

Temperature dependencies and thermal dynamical behavior of vibrational phonons related to different bonds/motions (e.g., K-O, Si-O, and Al-O) and O-H stretching, bending, and combinations bands, as well as those of NH4 ions, of muscovite have been investigated in detail at high temperatures using in situ infrared spectroscopy. Phonon modes of muscovite show a complex response to heating and dehydroxylation. The mode Grüneisen parameters of muscovite are largest for low-frequency bands and some bands have negative values. Approaching dehydroxylation, bands associated with K-O stretching, Al-OH bending, and Al-O vibrations exhibit significant variations, indicating modifications of local configurations related to these ions. The O-H stretching feature near 3627 cm-1 shows a change in temperature dependence of the peak position near or during dehydroxylation, and this is attributed to a dramatic loss of OH and changes in local environments. The infrared spectroscopic analyses carried out in situ or on quenched samples do not record the characteristic bands of dehydroxylation-induced H2O and these findings suggest that H2O is unlikely to be the principal diffusing species. The results suggest that de-ammoniation or loss of NH4 in muscovite takes place at temperatures near dehydroxylation. [ABSTRACT FROM AUTHOR]

Iron substitution into sphalerite, ZnS, has been studied systematically by infrared spectroscopy. A range of natural and synthetic compositions, (Zn1-xFex)S, 0 ≤ x ≤ 0.24, were examined. The IR spectrum of pure ZnS contains a single strong absorption band at 320 cm-1. With addition of FeS, the spectra become broader and shoulders appear. For compositions ≥9 mol% FeS, a splitting of the main peak occurs, and the spectra show two absorption maxima at approximately 300 and 315 cm-1, respectively. The observation of such extra features does not correspond to the usual behavior observed in other ternary mixed crystals, where either one-, two-, or mixed-mode behavior is observed. The spectra can be deconvoluted into up to three peaks, main Peaks A and B at around 300 and 315 cm-1, respectively, and a shoulder at around 330 cm-1 (Peak C). The positions and area of the peaks do not change significantly with increasing Fe content. The peak at 315 cm-1 is the main absorption peak of the host ZnS structure, and the peak at 300 cm-1 is an impurity induced mode. An effective linewidth parameter Δcorr was determined by autocorrelation analysis for each spectrum, but there are no obvious trends in the values of Δcorr that can be interpreted in terms of an inhomogeneous distribution of Fe within the sphalerite structure. [ABSTRACT FROM AUTHOR]

The high-temperature dehydroxylation and structural change of talc, Mg3 (Si2O5)2(OH) 2, has been investigated in detail using infrared (IR) spectroscopy. The data (in the region of 20-12000 cm-1) on quenched samples show that absorptions from structurally incorporated OH and OD, as well as NH4- like species, have similar temperature dependences in dehydroxylation. The OH species exhibit weak variation in frequency on heating, which is inconsistent with thermally induced weakening of O-H bonds. Dehydroxylation in talc is a complex process that involves proton migrations and formation of new OH species. Additional fundamental OH bands near 3665 and 3745 cm-1 became detectable near 900 °C. On further heating the former disappear near 1200 °C, whereas the latter became undetectable near 1350 °C. The occurrence of CO2 is observed in samples quenched between 600 and 1250 °C. The phonon spectrum (20-500 cm-1) of the dehydroxylate (obtained by annealing the sample at 1000 °C) gives features significantly different from that of talc, indicating the loss of the original layer structure. The IR data imply that the talc dehydroxylate consists of disordered SiO2 and enstatite (MgSiO3). Although MgSiO3 exists dominantly in the form of orthoenstatite, the characteristic bands of clinoenstatite phase are found to coexist in the samples treated at 1000 °C. The IR data from in situ measurements show that protons become mobile at temperatures below the dehydroxylation and an extra OH species near 3500 cm-1 develops on heating. This new species is not quenchable, and it decreases intensity on cooling and disappears at room temperature. The in situ results also indicate external carbon-related substances can diffuse into talc during dehydroxylation. [ABSTRACT FROM AUTHOR]

To reveal the nature of the zinc(II)-ion-induced ionochromic effect of bipyridine (bpy)-containing -conjugated polymers, we proposed an electrostatic interaction mechanism to illustrate our recent experimental findings Tian, L., et al. J. Phys. Chem. B2005109(15), 6944. Our theoretical analysis was based on the semiempirical (INDO/2) calculation of spectral properties and electronic structures of difluorene-substituted bpy model compounds. Our calculations show that the zinc(II)-induced ionochromic effect can be attributed to the electrostatic interaction between the zinc(II) ion and the polymer. Zinc(II) ion acts as a positive point charge with varied charge quantities, which is responsible for the red-shifted absorption spectra compared with those of the metal-free compound. The counterion ionochromic effect of the zinc(II) ion is also discussed. The proposed mechanism is possibly applied to the ionochromic effect induced by other metal ions such as Cd(II) and Hg(II). [ABSTRACT FROM AUTHOR]

Surface enhanced Raman scattering (SERS) spectroscopy was first utilized to study the photo-orientation behaviour of the photoreactive groups on a novel photo-alignment film surface and elucidate the generation mechanism of pretilt angle. The novel photo-alignment film was prepared by spin-coating a solution of ladderlike polysiloxane (LPS) bearing dual photoreactive group on an ITO surface and by irradiation with linear-polarized ultraviolet (LPUV) light. A Si- H terminal compound (M) containing an identical photosensitive part has been used to fabricate a model film for SERS investigation. [ABSTRACT FROM AUTHOR]