Conductive polyaniline/silica hybrids from sol-gel process

A hybrid material with a conductive organic network in an inorganic matrix has been prepared by in-situ hydrolysis/polycondensation of TEOS in an aqueous solution of a solubilized polyaniline. Due to intense hydrogen bonding (indicated by Si-29 NMR and FTIR) the conductive polymer is very well dispersed in the silica matrix. The Figure shows SEM images of a 46/54 wt.-% hybrid at two temperatures (left 20 degreesC, right 100 degreesC).

Preparation of poly(4-vinylpyridine)/silica hybrids supported cyclopentadienyltitanium trichloride (CpTiCl3) catalyst and styrene polymerization

Poly(4 - vinylpyridine)/silica( PVP/SiO2) organic - inorganic nanoscale hybrid was prepared using sol - gel method, in which PVP was used as an organic component and TEOS as a SiO2 precusor, This hybrid was used as CpTiCl3 support. The XPS and IR measurements showed that two kinds of catalytic active site were formed through analyzing the interaction mode between support and CpTiCl3. The results of styrene polymerization showed that syndiotactic was the highest at 50 degreesC. The catalytic activity was 1.09 x 10(6) g PS/ (mol Ti . h) at 70 degreesC when n(Al)/n(Ti) = 1500. GPC results showed a bimodal molecular weight distribution.

Helical single-lamellar crystals thermotropically formed in a synthetic nonracemic chiral main-chain polyester

Phase structures and transformation mechanisms of nonracemic chiral biological and synthetic polymers are fundamentally important topics in understanding their macroscopic responses in different environments. It has been known for many years that helical structures and morphologies can exist in low-ordered chiral liquid crystalline (LC) phases. However, when the chiral liquid crystals form highly ordered smectic liquid crystal phases, the helical morphology is suppressed due to the crystallization process. A double-twisted morphology has been observed in many liquid crystalline biopolymers such as dinoflaggellate chromosomes (in Prorocentrum micans) in an in vivo arrangement. Helical crystals grown from solution have been reported in the case of Bombyx mori silk fibroin crystals having the beta modification. This study describes a synthetic nonracemic chiral main-chain LC polyester that is able to thermotropically form helical single lamellar crystals. Flat single lamellar crystals can also be observed under the same crystallization condition. Moreover, flat and helical lamellae can coexist in one single lamellar crystal, within which one form can smoothly transform to the other. Both of these crystals possess the same structure, although translational symmetry is broken in the helical crystals. The polymer chain folding direction in both flat and helical lamellar crystals is determined to be identical, and it is always along the long axis of the lamellae. This finding provides an opportunity to study the chirality effect on phase structure, morphology, and transformation in condensed states of chiral materials. [S0163-1829(99)01042-5].

Investigation of a series of synthetic cationic porphyrins using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was used to study a series of synthetic cationic porphyrins as the perchlorate and bromide salts. This work presents the analytical results for the porphyrins obtained using 2,5-dihydroxybenzoic acid (DHB) and 1,8,9-anthratriol as matrices. The selective use of matrix affects ion formation from these porphyrins. By using DHB as the matrix, we not only observed [M - nCIO(4)](+) (n = 1-4) ions, but also obtained [2M - nCIO(4)](+) (n = 2-7) ions from the synthetic cationic porphyrins. The space volume of the side chains (R groups) and the nature of the anions (Br- or CIO4-) affected the relative importance of monomeric and dimeric ions of the porphyrin. The possible mechanisms of desorption and ionization of these cationic porphyrins were also considered in this study. MALDI-TOFMS proved to be a very useful method for obtaining structural information on these synthetic cationic porphyrins. Copyright (C) 1999 John Whey & Sons, Ltd.

A novel synthetic method to phenyl-capped penta- and hexaaniline

A new convenient method is reported for the synthesis of the phenyl-capped pentamer and hexamer of aniline. The method was accomplished by the reaction of the parent aniline tetramer in the pernigraniline oxidation state with diphenylamine and N-phenyl-1,4-phenylenediamine in the leucoemeraldine oxidation state, respectively. The mechanism probably involves the formation of cation radicals and their coupling.

Lanthanide binuclear macrocyclic complexes as synthetic enzymes for the cleavage of DNA

Lanthanide binuclear complexes can accelerate the cleavage of pUC19 plasmid DNA, yielding predominantly linear form. The saturation kinetics of the cleavage of pUC19 was studied. The observed rates with lanthanide binuclear complexes showed the expected increase with the catalyst concentration. The rate of cleavage is greater than that of lanthanide ions alone. (C) 1998 Elsevier Science B.V. All rights reserved.

Reactions of C-60 with R(3)SnH: A new synthetic route to C-60(RH)(n) and the property of C-60 to catalyze radical reactions

A new method for the preparation of polyalkyl and polyarenefullerene derivatives C-60(RH)(n)(R=Bu,n=1-3; R=Ph,n=1-10) by the reaction of C-60 with organotin hydride in toluene is described. Another series of products of stannanes R(a)Sn(b)H(c) (R=Bu, a=3-8, b=1-4, c=0-3 R=Ph, a=3-11, b=1-5, c=0-4) were also obtained, which shows that C-60 can catalyze polymerization of organic-tin. These products were determined by mass and infrared spectrometry. And the possible reaction mechanisms are discussed.

Studies on the synthetic, structural, electrical and magnetic properties of Ln(n)MCo(n)O(3n+1) (Ln=Sm, Gd; M=Sr, Ba; n=1,2)

Three new oxides Sm2SrCo2O7, Sm2BaCo2O7 and Gd2SrCo2O7 have been synthesized successfully by solid state reaction mathod. The X-Ray diffraction spectra show that they are all isostructural with Sr3Ti2O7, and Ln(2)SrCo(2)O(7)(Ln=Sm,Gd) crystallized in tetragonal system, Sm2BaCo2O7 in orthrhombic system. The Co-O bonds in CoO2 planes of Ln(2)SrCo(2)O(7) are shorter than those of LnSrCoO(4)(Ln=Sm, Gd), and so their delectrons are more delocalized and their electrical resistivities are smaller. The electrical resistivities versus temperature in the range 300 similar to 1100K showed that the five brides show the characters of weakly localized systems. In the lower temperature range, the magnetic behaviors of Gd2SrCo2O7 and GdSrCoO4 fit Curie-Weiss law well, and the magnetic exchange reaction in CoO2 sublattices of Gd2SrCo2O7 is ferromagnetic, but that of GdSrCoO4 is antiferromagnetic. The other three oxides with Sm3+ showed complex magnetic behaviors which is perhaps related with the complexity of Sm3+.

STUDIES ON THE SYNTHETIC, STRUCTURAL, ELECTRICAL, AND MAGNETIC-PROPERTIES OF THE NEW LAYERED OXIDES LN(2)MCO(2)O(7) (LN=SM, GD, M=SR, BA)

Three new oxides Ln(2)MCo(2)O(7) (Ln = Sm, Gd; M = Sr, Ba) have been synthesized in solid state reaction method. The powder X-ray diffraction spectra show that they are all isostructural with Sr3Ti2O7. The electrical resistivities in the temperature range 300-1100 K show that they are all semiconductors, and a transition to metals is observed at 1053, 1053, and 573 K for Sm2SrCo2O7, Gd2SrCo2O7, and Sm2BaCo2O7, respectively. The magnetic suspectivities of Gd2SrCo2O7 in the temperature range 300-673 K fit the Curie-Weiss law well. A plateau is observed in the curves of Sm(2)MCo(2)O(7) (M = Sr, Ba) which is attributed to the configuration state change of Co(III) from low spin to high spin. (C) 1995 Academic Press, Inc.

THE PHYSICAL AND CHEMICAL-PROPERTIES OF SYNTHETIC AND NATURAL JADEITE FOR JEWELRY

Jadeite was synthesized from its glass of stoichiometric composition NaAlSi2O6, and a colouring agent Cr2O3 (0.3-0.6 wt%) was added to achieve the emerald colour. The conditions employed were a pressure range of 3.0-5.0 GPa and a temperature range of 1150

Hybrids between olive flounder Paralichthys olivaceus and stone flounder Kareius bicoloratus: karyotype, allozyme and RAPD analyses

The hybrid between olive flounder Paralichthys olivaceus and stone flounder Kareius bicoloratus was produced by artificial insemination of olive flounder eggs with stone flounder sperm. Sinistral and dextral are two types of hybrid progeny after metamorphosis. Karyotypes of both hybrid flounders are the same as those of the two parental species. Of the 22 loci examined from 12 allozymes, 12 confirmed hybridization of the paternal and maternal loci in hybrids and no difference was found in allozyme patterns of sinistral and dextral hybrid fishes. RAPD patterns of these specimens were also studied with 38 primers selected from 104 tested. Among them, the PCR products of 30 primers showed hybridization of the paternal and maternal bands. Genetic variation between hybrids and their parental stocks was analyzed by RAPD using 10 of the above 38 primers. The average heterozygosity and genetic distance were calculated. The results suggested that the filial generation could inherit a little more genetic materials from paternal fish than that from maternal fish.

Comparative growth and viability of hybrids between two populations of Chinese shrimp (Fennropenaeus chinensis)

Fenneropenaeus chinensis is confined to the Yellow Sea and Bohai Sea in China and the West Coast of the Korean Peninsula. Intra- and intercross populations were produced between Rushany (YP) and Korean (KN) populations. Seven traits were recorded. The heterosis of hybrids was computed and comparison between treatments was performed by ANOVA. At the fourth month after post-larvae, six indexes of growth trait and viability showed a range of heterosis, ranging from 0.514% to 14.950%. At the fifth month after post-larvae, six indexes of growth trait and viability ranged from -9.000% to 19.090%. The negative heterosis was observed in CL, HST and viability. The heterosis of KN female xYP male tended generally to increase as the age of the Chinese shrimp increased while the heterosis of YP female xKN male tended to decrease. The results indicated that the viability of reciprocal hybrids were not significantly different (P > 0.05) from their parents during the experiment. The result of ANOVA indicated that the F1 hybrids were significantly different (P < 0.05) in WST and TW at the fourth month. The multiple comparisons of LSD test indicated that the hybrids of YP female xKN male were significantly different (P < 0.05) from their parents in TW. The hybrids of YP female xKN male were significantly different (P < 0.05) from the other three combinations in WST. At the fifth months, the F1 hybrids had significant difference (P < 0.05) in body weight while other traits showed no significant differences (P > 0.05) from their parents. The multiple comparisons of LSD test indicated that the hybrids of KN female xYP male were significantly different (P < 0.05) from the KN parents in TW. The results indicate that in experimental conditions, the F-1 hybrids created from two populations of Chinese shrimp showed a certain level of heterosis for growth performance and viability. The crossing scheme may improve growth performance and viability in Chinese shrimp, but the improvement may be limited because effective crossbreeding requires the maintenance of pure, preferably inbred, lines and possibly involves specialized sire and dam lines. Therefore, the exploitation of heterosis through single crossbreeding in Chinese shrimp is of limited utility in practical commercial shrimp aquaculture in spite of the potential of significant heterosis. The crossbreeding of different populations can be applied in the establishment of base populations.

Remote sensing of ocean waves by along-track interferometric synthetic aperture radar

A new wave retrieval method for the Along-Track Interferometric Synthetic Aperture Radar (AT-InSAR) phase image is presented. The new algorithm, named parametric retrieval algorithm (PRA), uses the full nonlinear mapping relations. It differs from previous retrieval algorithms in that it does not require a priori information about the sea state or the wind vector from scatterometer data. Instead, it combines the observed AT-InSAR phase spectrum and assumed wind vector to estimate the wind sea spectrum. The method has been validated using several C-band and X-band HH-polarized AT-InSAR observations collocated with spectral buoy measurements. In this paper, X-band and C-band HH-polarized AT-InSAR phase images of ocean waves are first used to study AT-InSAR wave imaging fidelity. The resulting phase spectra are quantitatively compared with forward-mapped in situ directional wave spectra collocated with the AT-InSAR observations. Subsequently, we combine the parametric retrieval algorithm (PRA) with X-band and C-band HH-polarized AT-InSAR phase images to retrieve ocean wave spectra. The results show that the ocean wavelengths, wave directions, and significant wave heights estimated from the retrieved ocean wave spectra are in agreement with the buoy measurements.

On the nonlinear integral transform of an ocean wave spectrum into an along-track interferometric synthetic aperture radar image spectrum

We present a new nonlinear integral transform relating the ocean wave spectrum to the along-track interferometric synthetic aperture radar (AT-INSAR) image spectrum. The AT-INSAR, which is a synthetic aperture radar (SAR) employing two antennas displaced along the platform's flight direction, is considered to be a better instrument for imaging ocean waves than the SAR. This is because the AT-INSAR yields the phase spectrum and not only the amplitude spectrum as with the conventional SAR. While the SAR and AT-INSAR amplitude spectra depend strongly on the modulation of the normalized radar cross section (NRCS) by the long ocean waves, which is poorly known, the phase spectrum depends only weakly on this modulation. By measuring the phase difference between the signals received by both antennas, AT-INSAR measures the radial component of the orbital velocity associated with the ocean waves, which is related to the ocean wave height field by a well-known transfer function. The nonlinear integral transform derived in this paper differs from the one previously derived by Bao et al. [1999] by an additional term containing the derivative of the radial component of the orbital velocity associated with the long ocean waves. By carrying out numerical simulations, we show that, in general, this additional term cannot be neglected. Furthermore, we present two new quasi-linear approximations to the nonlinear integral transform relating the ocean wave spectrum to the AT-INSAR phase spectrum.