bluuebunny/crossref_metadata_2025_split huggingface dataset:
Summertime anomalous warming over the midlatitude western North Pacific and its relationships to the modulation of the Asian monsoon
Authors: Ueda Hiroaki , Kawamura Ryuichi 
Published: June 2004

AbstractAn anomalously warm sea‐surface temperature (SST) developed to the east of Japan in the midlatitude western North Pacific (WNP) during three consecutive years, from 1999 through to 2001. The anomalies in those years simultaneously reached a maximum deviation (>2.5 °C) during the boreal summer. Prior to this seasonal peaking, convective activity was significantly enhanced around the Philippine Sea, while Japan and the adjacent ocean were characterized by weak convection. Almost concurrently with this, the lower troposphere in the subtropical WNP exhibited an anomalous cyclonic flow slightly to the northwest of the Philippine convection. In contrast, anticyclonic anomalies prevailed over the midlatitude WNP in the area centred around 35 °N, 150 °E.The many changes observed in the convection and circulation fields can be explained by wave trains related to the stationary Rossby wave. In situ heat budget analysis at the ocean surface indicates that, in association with the midlatitude anticyclone, the combined effect of reduced evaporative cooling and intensified downward shortwave radiation flux can be responsible for the salient increase in SST. Furthermore, analysis of the subsurface water reveals that the anomalous state in the midlatitude WNP was limited in the near‐surface layer, which is consistent with the result of the heat exchange at the ocean surface.Finally, these anomalous years correspond to a cold episode of El Niño, suggesting the potential predictability of the Asian summer monsoon. In view of this, we also examine precursor signals in the pre‐monsoon season over the tropical Indian Ocean and their possible linkage to summertime climate conditions in the midlatitude WNP. Copyright © 2004 Royal Meteorological Society
Adsorption of phenylacetylene on gold nanoparticle surfaces investigated by surface‐enhanced Raman scattering
Authors: Joo Sang‐Woo , Kim Kwan 
Published: June 2004

AbstractThe adsorption of phenylacetylene (PA) on gold nanoparticle surfaces was investigated by means of surface‐enhanced Raman scattering (SERS). The aggregation behaviors were examined by UV–visible absorption spectroscopy and transmission electron microscopy. The phenyl ring of PA appeared to assume a perpendicular orientation with respect to the gold surface from the presence of the ν(CH) band at ∼3060 cm−1. Neither a substantial red shift nor a significant band broadening of the ring breathing modes implied that a direct ring π‐orbital interaction from the phenyl ring with gold substrates should be low. The SERS spectrum of PA on Au surfaces was analyzed by determining the relative enhancement factor of each vibrational band. The multiple peaks in the ν(CC) stretching region were found to vary in the presence of other ionic species. Copyright © 2004 John Wiley & Sons, Ltd.
Fourier transform Raman spectroscopic studies of the curing of cyanoacrylate glue
Authors: Edwards Howell G. M. , Day Joanna S. 
Published: June 2004

AbstractThe spontaneous polymerization of ethyl 2‐cyanoacrylate (‘superglue’) in a sealed glass tube was studied using Fourier transform Raman spectroscopy with 1064 nm excitation. The spectra of the monomer and the polymer were characterized and the polymerization process was monitored qualitatively over a time interval of 92 days. Even after this time lapse from initiation, the reaction had not proceeded to completion and 15% monomer remained in the polymerized specimen, based on ν(CC) band intensity depletion and on the evolution of the ν(CN) feature; the latter becomes asymmetric as the reaction proceeds owing to the appearance of the polymeric ν(CN) stretch at 2247 cm−1 and the diminution in intensity of the monomer band at 2239 cm−1. The results of this work are of relevance to the non‐destructive Raman spectroscopic analysis of cyanoacrylate‐fumed latent fingerprints at forensic crime scenes. Copyright © 2004 John Wiley & Sons, Ltd.
Raman spectroscopic signature of life in a living yeast cell
Authors: Huang Yu‐San , Karashima Takeshi , Yamamoto Masayuki , Ogura Takashi , Hamaguchi Hiro‐o 
Published: June 2004

AbstractWe have discovered a Raman spectroscopic signature that sharply reflects the metabolic activity of a mitochondrion in a living yeast cell. Raman mapping experiments on a GFP‐labeled yeast cell showed that this signature originated exclusively from mitochondria. Addition of KCN caused a rapid decrease and subsequent disappearance of the signature followed by gradual changes of the phospholipid Raman bands, indicating that respiration was first inhibited by KCN and then lowered metabolic activity gradually deteriorated the double‐membrane structure of a mitochondrion. We can now monitor the life and death of a single cell by time‐ and space‐resolved Raman spectroscopy. Copyright © 2004 John Wiley & Sons, Ltd.
Separation and characterisation of sphingoceramides by high‐performance liquid chromatography‐electrospray ionisation mass spectrometry
Authors: Camera Emanuela , Picardo Mauro , Presutti Carla , Catarcini Paolo , Fanali Salvatore 
Published: June 2004

AbstractWe developed a simple and reliable analytical method for the quantification and the characterization of ceramides extracted from biological samples by high‐performance liquid chromatography (HPLC) coupled to electrospray ionisation tandem mass spectrometry (ESI/MS/MS). The chromatographic separation of analytes was carried out in a RP8 column, eluting with a methanol‐water mixture in gradient elution mode. The separated lipids were detected by total ion monitoring and characterised by MS/MS spectra; quantitative analysis was performed by integrating the extracted ion peaks obtained in the negative ion mode. Good repeatability was obtained for retention time (0.3–2%), peak area ratio (A S/A IS, 2–8%), as well as limit of detection (LOD, 5–26 pg) and quantification (LOQ, 13–53 pg). The method was validated for the analysis of N‐palmitoyl‐D‐erythro‐sphingosine (Cer16), N‐stearoyl‐D‐erythro‐sphingosine (Cer18), N‐tetracosanoyl‐D‐erythro‐sphingosine (N24 : 0, lignoceric ceramide, Cer24:0), and N‐tetracos‐15 ´‐enoyl‐D‐erythro‐sphingosine (N24 : 1, nervonic ceramide, Cer24 : 1), giving good results. Lipid mixtures, extracted from skin and epidermal cells, were analysed for their content of the studied ceramides.
Dynamic solid phase microextraction for sampling of airborne sarin with gas chromatography‐mass spectrometry for rapid field detection and quantification
Authors: Hook Gary L. , Jackson Lepage Carmela , Miller Stephen I. , Smith Philip A. 
Published: June 2004

AbstractA portable dynamic air sampler and solid phase microextraction were used to simultaneously detect, identify, and quantify airborne sarin with immediate analysis of samples using a field portable gas chromatography‐mass spectrometry system. A mathematical model was used with knowledge of the mass of sarin trapped, linear air velocity past the exposed sampling fiber, and sample duration allowing calculation of concentration estimates. For organizations with suitable field portable instrumentation, these methods are potentially useful for rapid onsite detection and quantification of high concern analytes, either through direct environmental sampling or through sampling of air collected in bags.
Rapid and sensitive determination of morphine in street opium samples by thermal desorption gas chromatography using a microfurnace pyrolyzer
Authors: Hida Minemasa , Mitsui Toshiyuki , Tsuge Shin , Ohtani Hajime 
Published: June 2004

AbstractThermal desorption of the alkaloids in opium samples at 300°C using a vertical microfurnace pyrolyzer was followed by their on‐line gas chromatographic (GC) analysis on a large‐bore glass capillary column. This method permitted rapid and sensitive determination of the content of the main alkaloid, morphine, in the small (ca. 100 μg) opium samples with a relative standard deviation within 4% for 5 runs. The observed morphine contents of about 12 to 15 w/w% in the given opium samples were in fairly good agreement with those estimated by a conventional GC‐MS method.
Oxidation of niobium particles embedded in a sintered ceramic matrix
Authors: Tommaselli M. A. G. , Mariano N. A. , Pallone E. M. J. A. , Kuri S. E. 
Published: June 2004

AbstractThe toughness of ceramic materials can be improved through the inclusion of metallic particles in the ceramic matrix. The plastic deformation of the particles limits the rupture of the ceramic matrix. Al2O3‐Nb composites show the ability of niobium to form a strong bond with Al2O3, but the poor resistance to oxidation of niobium hinders the use of niobium for high temperature applications. The study of the oxidation mechanism was done using thermogravimetric analysis under an oxygen atmosphere in order to obtain the oxidation reaction rate constants of the Al2O3‐Nb composite. At the beginning the oxidation kinetics are linear, probably due to a great availability of oxygen. Later on, the oxidation mechanism showed to be parabolic, indicating that the process depends on the oxygen diffusion through the ceramic matrix.
Investigations of an ethanolamine‐based corrosion inhibitor system for surface treatment of reinforced concrete
Authors: Ngala V. T. , Page C. L. , Page M. M. 
Published: June 2004

AbstractLaboratory investigations were performed to assess the efficacy of a proprietary ethanolamine‐based corrosion inhibitor system when applied to the surface of reinforced concrete specimens that were chloride‐contaminated to varying extents in the presence or absence of carbonation. The corrosion responses of embedded steel bars at various depths of cover were monitored electrochemically during a controlled programme of cyclic wetting and drying undertaken for several months prior to the inhibitor treatment and for approximately eighteen months thereafter. Gravimetric measurements of the quantities and distribution of corrosion on the steel were also made on completion of the exposure tests. Analysis of aqueous extracts from treated concrete revealed that the ethanolamine component of the inhibitor system penetrated to depths of more than 15 mm within the concrete. It was found that, for inhibitor‐treated specimens, there was some reduction in the corrosion rate of pre‐corroding steel at low cover depths in non‐carbonated concrete with modest levels of chloride contamination. At higher levels of chloride contamination and in carbonated specimens, however, the ethanolamine‐based inhibitor was apparently ineffective under the conditions investigated.
Preparation of Scratch‐ and Abrasion‐Resistant Polymeric Nanocomposites by Monomer Grafting onto Nanoparticles, 4
Authors: Bauer Frank , Sauerland Volker , Ernst Horst , Gläsel Hans‐Jürgen , Naumov Sergej , Mehnert Reiner 
Published: June 2004

AbstractTo obtain transparent, scratch‐ and abrasion‐resistant coating materials a high content of nanosized silica and alumina filler was embedded in radiation‐curable acrylate formulations by acid catalyzed silylation using trialkoxysilanes. 29Si magic angle spinning (MAS) NMR spectroscopy and matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOF MS) were used to elucidate the structure of the surface‐grafted methacryloxypropyl‐, vinyl‐, and n‐propyltrimethoxysilane. 29Si MAS NMR measurements revealed a predominance of T2 and T3 structures of silicon atoms, i.e., silane oligomers have been formed by an extensive loss of water. For methacryloxypropyltrimethoxysilane, the proportion of the highly condensed T3 silicon atoms was estimated to be 75%. In accordance with these NMR findings, MALDI‐TOF MS showed highly condensed oligomeric siloxanes of more than 20 monomeric silane units. The degree of silane condensation is higher on alumina than on silica, irrespective to the addition of maleic acid as catalyst. Moreover, completely condensed silsesquioxanes, e.g., octamers, decamers, and dodecamers, were detected. Based on the observed MS pattern, a ladder‐like arrangement of two linked siloxane chains forming connected eight‐membered rings is proposed, which is similar for all of the condensed organosilanes under study. The grafted polysiloxanes lead to an organophilation of inorganic nanofillers and improve their dispersibility in acrylate suspensions.
Proposed ladder‐like arrangement of the T3 structure of silicon atoms in polysiloxanes grafted on the silica surface.imageProposed ladder‐like arrangement of the T3 structure of silicon atoms in polysiloxanes grafted on the silica surface.
Self‐Assembly of Porphyrin‐Centered Amphiphilic Star Block Copolymer into Polymeric Vesicular Aggregates
Authors: Jin Ren‐Hua 
Published: June 2004

AbstractPolymeric vesicular aggregates with spherical and tubular shapes were formed from the self‐assembly of a porphyrin‐centered amphiphilic star poly(oxazoline) [poly(phenyloxazoline)‐block‐poly(methyloxazoline)] in an DMF/water mixture containing excess DMF. The aggregates were evaluated by means of UV‐Vis, fluorescent, 1H NMR spectroscopies, and optical microscopy. The driving force to induce the vesicular aggregates is the interactions between poly(phenyloxazoline) segments which were insoluble in DMF rich aqueous medium.
Polymeric vesicular aggregates with spherical and tubular shapes were formed from the self‐assembly of a porphyrin‐centered amphiphilic star poly(oxazoline) [poly(phenyloxazoline)‐block‐poly(methyloxazoline)] in an DMF/water mixture.imagePolymeric vesicular aggregates with spherical and tubular shapes were formed from the self‐assembly of a porphyrin‐centered amphiphilic star poly(oxazoline) [poly(phenyloxazoline)‐block‐poly(methyloxazoline)] in an DMF/water mixture.
Characterization of Solvation Environment Provided by Dilute Poly(sulfonyl maleic anhydride‐co‐dodecyl vinyl ether) Solutions at Various pH Using Pyrene and 1,3‐Bis(1‐pyrenyl)propane as Fluorescence Probes
Authors: Pandey Siddharth , Redden Rebecca A. , Fletcher Kristin A. , Palmer Christopher P. 
Published: June 2004

AbstractSolubilization environments afforded by dilute aqueous solutions of poly(sulfonyl maleic anhydride‐co‐dodecyl vinyl ether) [PSMADVE, 1 wt.‐%] at pH 4, 7, and 10 are investigated using pyrene and 1,3‐bis(1‐pyrenyl)propane as fluorescence probes. While pyrene is a common polarity probe, intramolecular excimer formation in 1,3‐bis(1‐pyrenyl)propane makes it an interesting cybotactic region microviscosity probe. Results for pyrene II/IIII indicate that the most hydrophobic solubilization site is afforded at pH 4 followed by pH 10 and pH 7. The dipolarity indicated by pyrene is similar to that observed in m‐ and o‐xylene, toluene, and butyl benzoate. The solvation microenvironment afforded by the PSMADVE solutions is more hydrophobic than that observed within sodium dodecyl sulfate micellar solution. Additionally, further investigation of the relative size of the solubilization site revealed that the polymer solutions promoted intermolecular pyrene excimer formation at relatively low pyrene concentrations, indicating the possibility of localized concentration enhancement within the solvation pockets and/or compartmentalization of the solute molecules. This observation was most prominent at pH 10 and least at pH 7. 1,3‐Bis(1‐pyrenyl)propane intramolecular excimer formation efficiency at pH 4 is slightly higher than that for neat ethylene glycol, while at pH 10 is similar to that observed in 1‐octanol or dimethyl sulfoxide. Anomalously high excimer‐to‐monomer intensity ratio at pH 7 could be due to probe ground state heterogeneity, i.e., the existence of probe moieties in the ground state where the two pyrenyl groups are already aggregated. This is demonstrated by the fluorescence excitation data. Presence of the ground state aggregated form may give rise to anomalously high excimer formation efficiency.
Structures of fluorescence probes pyrene and 1,3‐bis(1‐pyrenyl)propane.imageStructures of fluorescence probes pyrene and 1,3‐bis(1‐pyrenyl)propane.
Effect of a Polymeric Additive on the Pore‐Size Distribution and Shrinking Process of a Hydrogel Network
Authors: Lynch Isuelt , Dawson Kenneth A. 
Published: June 2004

AbstractA systematic comparison of the effect of architectural modifications to the network structure on the internal microstructure of N‐isopropylacrylamide (NIPA) based hydrogels showed that the addition of a second component to the network significantly increased the proportion of macropores in the network. The second components considered were short poly(N‐isopropylacrylamide) (PNIPAM) chains grafted to the network backbone, high‐molecular‐weight polyacrylamide (PAM) chains, or microsphere particles of PNIPAM. Structures are proposed for each of the modified gel networks taking into account the new structural information. Through a combination of the pore size and network structure data reported here, and with the shrinking data obtained previously, shrinking mechanisms are proposed for each of the modified network structures. In all cases, the enhanced shrinking rates were directly caused by the presence of the second component, which acted as nuclei for shrinking (graft‐PNIPAM and PNIPAM microspheres) or as water‐release channels (PAM gel), and indirectly caused by the second components via their affect on the network microstructure.
Proposed structures for the architecturally modified gels based on the pore‐size information. Graft‐PNIPAM gel. The freely mobile graft chains prevent chains from meeting resulting in larger pores.imageProposed structures for the architecturally modified gels based on the pore‐size information. Graft‐PNIPAM gel. The freely mobile graft chains prevent chains from meeting resulting in larger pores.
NMR Characterization of Carbazole‐Substituted Norbornene Comonomer 9‐(Bicyclo[2.2.1.]hept‐5‐en‐2‐ylmethyl)‐9H‐carbazole (BHMCZ) and Poly(ethylene‐co‐BHMCZ) Copolymer
Authors: Mustonen Ilpo , Hukka Terttu , Pakkanen Tuula T. 
Published: June 2004

AbstractCarbazole‐substituted norbornene comonomer 9‐(bicyclo[2.2.1.]hept‐5‐en‐2‐ylmethyl)‐9H‐carbazole (BHMCZ) can be copolymerized with ethylene using the [Ph2C(Ind)(Cp)ZrCl2] catalyst and methylaluminoxane (MAO) cocatalyst system. The microstructures of BHMCZ comonomer and of ethylene–BHMCZ copolymer containing 4.6 mol‐% BHMCZ units in the chain were characterized by one‐dimensional 13C DEPT and two‐dimensional homonuclear 1H‐1H COSY and heteronuclear 1H‐13C HXCO NMR spectroscopy. The BHMCZ comonomer appears as endo and exo stereoisomers, which were identified on the basis of chemical shifts, signal multiplicities, and coupling in the 2D NMR spectra. The NMR information on the BHMCZ isomers was used to assist in the determination of the chemical shifts and microstructure of ethylene–BHMCZ copolymer. The NMR analysis of ethylene–BHMCZ copolymer indicated that exo‐BHMCZ polymerizes with ethylene slightly more readily than does endo‐BHMCZ under the polymerization conditions employed.
Isolated segments of exo(2)‐exo(5)‐exo(6) and endo(2)‐exo(5)‐exo(6) ethylene‐BHMCZ copolymer showing carbon atom numbering.imageIsolated segments of exo(2)‐exo(5)‐exo(6) and endo(2)‐exo(5)‐exo(6) ethylene‐BHMCZ copolymer showing carbon atom numbering.
Surface‐Enhanced Raman Scattering on Molecularly Imprinted Polymers in Water
Authors: Kostrewa Stefan , Emgenbroich Marco , Klockow Dieter , Wulff Günter 
Published: June 2004

AbstractMolecularly imprinted polymer layers were prepared on SERS‐active surfaces in order to directly monitor the uptake and release of certain substances to this polymer layer by surface enhanced Raman‐scattering (SERS). The imprinting system consisted of either (2S,3S)‐(+)‐di‐O‐benzoyl‐tartaric acid (1) or N‐benzyloxycarbonyl‐(L)‐aspartic acid (2) as templates. As binding site N,N′‐diethyl‐4‐vinylbenzamidine (3) was used which binds in a 2:1 complex to the templates. The release and uptake of the templates to the imprinted polymer could be followed in aqueous solution under physiological conditions (aqueous buffer, ambient temperature). The recorded SERS bands can be unequivocally assigned to the substances taken up, and it is therefore possible to directly detect a certain substance in the imprinted layer. Release and uptake are quick processes occurring within minutes. This method also offers the opportunity to use these layers in chemosensors in which case the stability has to be further increased.
SERS spectra of polymer coatings containing the template N‐benzyloxycarbonyl‐(L)‐aspartic acid (2) on gold and on silver surfaces, Raman spectra of pure 2 (template) and of a HEPES buffer solution (0.1 M, pH 7.3) which was used for the adsorption measurement.imageSERS spectra of polymer coatings containing the template N‐benzyloxycarbonyl‐(L)‐aspartic acid (2) on gold and on silver surfaces, Raman spectra of pure 2 (template) and of a HEPES buffer solution (0.1 M, pH 7.3) which was used for the adsorption measurement.
Synthesis, Characterization, and Polymerization Kinetics of Novel Ladder‐Like Polysilsesquioxanes Containing Side‐Chain Propyl Methacrylate Groups
Authors: Gopala Krishnan P. Santhana , He Chaobin 
Published: June 2004

AbstractThree ladder‐like polysilsesquioxanes containing side‐chain propyl methacrylate groups have been synthesized successfully by stepwise coupling polymerization. The prepared ladder‐like polymers are polysilsesquioxanes containing 100 mol‐% propyl methacrylate side groups and two copolymers containing 70 mol‐% methyl or phenyl groups and 30 mol‐% propyl methacrylate side groups. They were characterized by FT‐IR, 1H NMR, proton‐decoupled 13C NMR, and 29Si NMR spectroscopies, gel‐permeation chromatography (GPC), wide‐angle X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and thermo‐gravimetric analysis (TGA). Characterization data indicate that these polymers have ordered ladder‐like structures with possible defects. At appropriate conditions, crystals of homopolymer were grown and are in the shape of a parallelogram. All three polymers were cured by 2,2′‐azoisobutyronitrile (1% w/w) and the kinetics for the bulk polymerization of these polysilsesquioxanes was followed by dynamic DSC method. Ozawa and Kissinger methods were used to calculate the activation energy for curing. Both the frequency factor and the activation energy of the homopolymer were found to be higher than the copolymers. Cured samples had a higher thermal stability than uncured samples.
Chemical structure of LPS.imageChemical structure of LPS.