bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vibrational spectroscopic studies, conformations and ab initio calculations of 1,1,1‐trifluoropropyltrifluorosilane
Authors: Gruodis A. , Aleksa V. , Powell D. L. , Klaeboe P. , Nielsen C. J. , Guirgis G. A. , Durig J. R. 
Published: September 2003

AbstractInfrared spectra of 1,1,1‐trifluoropropyltrifluorosilane (CF3CH2CH2SiF3) were obtained in the vapour, amorphous and crystalline solid phases in the range 4000–50 cm−1. Additional spectra in argon and nitrogen matrices at 4.8 K were recorded before and after annealing to temperatures of 20–36 K. Raman spectra of the compound as a liquid were recorded at various temperatures between 298 and 163 K and spectra of the amorphous and crystalline solids were obtained. The spectra revealed the existence of two conformers (anti and gauche) in the fluid phases and in the matrices. When the vapour was shock‐frozen on a cold‐finger at 78 K and subsequently annealed to 120–150 K, 12 mostly weak Raman bands vanished in the crystal. Much smaller variations were observed in the corresponding infrared spectra after annealing. However, the spectra indicated the existence of two different crystals, formed after annealing the amorphous solid to 120 and to 150 K; both crystals contained the same conformer (anti). Raman and IR spectra of 1,1,1‐trifluoropropyltrifluorosilane in cyclohexane, carbon tetrachloride and acetonitrile revealed conformational displacements with solvent polarity. From intensity variations between 298 and 223 K of the Raman pair 639/665 cm−1, ΔH° (gauche–anti) = 3.4 ± 0.3 kJ mol−1 was obtained in the liquid. Annealing experiments indicate that the anti conformer also has a lower energy in argon and nitrogen matrices; moreover, the low‐energy conformer is present in the crystal. The spectra of both conformers have been interpreted in detail. Ab initio calculations at the HF/6–311(d), HF/6–311 G (3df,3pd) and MP2/G–31(d) levels gave optimized geometries, infrared and Raman intensities and scaled vibrational wavenumbers for the anti and gauche conformers. The conformational energy difference derived was 5.3 kJ mol−1 with anti being the low‐energy conformer. Copyright © 2003 John Wiley & Sons, Ltd.
Detection of single lipid bilayers with coherent anti‐Stokes Raman scattering (CARS) microscopy
Authors: Potma Eric O. , Xie X. S. 
Published: September 2003

AbstractWe investigated vibrational imaging of phospholipid bilayers with CARS microscopy. Single lipid membranes of supported bilayers, giant unilamellar vesicles and intact erythrocyte membrane are detected with the strong resonant signal of the C–H stretching vibration. In addition, it is shown that the CARS signal field of the lipids near the glass/water interface is amplified through mixing with the back‐reflected non‐resonant CARS field of the glass coverslip. Furthermore, interference effects between two separate bilayers are observed, allowing intermembrane distances to be determined beyond the diffraction‐limited resolution of the microscope. Copyright © 2003 John Wiley & Sons, Ltd.
Tip‐enhanced Raman microscopy: practicalities and limitations
Authors: Richards D. , Milner R. G. , Huang F. , Festy F. 
Published: September 2003

AbstractThe feasibility of apertureless scanning near‐field Raman microscopy, exploiting the local enhancement in Raman scattering in the vicinity of a silver or gold tip, was investigated. Using the finite difference time domain method we calculated the enhancement of electric field strength, and hence Raman scattering, achieved through the resonant excitation of local modes in the tip. By modelling the frequency‐dependent dielectric response of the metal tip we were able to highlight the resonant nature of the tip‐ enhancement and determine the excitation wavelength required for the strongest electric field enhancement, and hence Raman scattering intensity, which occurs for the excitation of modes localized at the tip apex. It is demonstrated that a peak Raman enhancement of 107‐fold should be achievable with <5 nm spatial resolution. We show that surface‐enhanced Raman scattering from carbon contamination on a silver or gold tip can be significant. However, we find for a tip of radius of curvature 20 nm that the Raman enhancement should decay totally within 20 nm from the tip. Hence withdrawal of the tip by this distance should lead to the disappearance of the tip‐enhanced signal, leaving only that from carbon contamination on the tip itself and the intrinsic signal from the sample. Copyright © 2003 John Wiley & Sons, Ltd.
Local enhancement of coherent anti‐Stokes Raman scattering by isolated gold nanoparticles
Authors: Ichimura Taro , Hayazawa Norihiko , Hashimoto Mamoru , Inouye Yasushi , Kawata Satoshi 
Published: September 2003

AbstractWe observed local enhancement of coherent anti‐Stokes Raman scattering (CARS) by isolated gold nanoparticles. CARS signals from adenine molecules of a DNA base attached to isolated gold nanoparticles were strongly enhanced owing to the electromagnetic enhancement at the local proximity of the particles. The localization of the enhancement was successfully observed by a CARS microscope using a collinear configuration of tightly focused lasers. The CARS spectrum of adenine was enhanced by a factor of 2000 and was in good agreement with the measured spontaneous Raman spectrum. Copyright © 2003 John Wiley & Sons, Ltd.
The electric field at the apex of a near‐field probe: implications for nano‐Raman spectroscopy
Authors: Hallen H. D. , Jahncke C. L. 
Published: September 2003

AbstractNear‐field or nano‐Raman spectroscopy is different from its far‐field counterpart in several important respects. We present a unified view of nano‐Raman spectroscopy that accounts for these differences, which include surface enhancement, propagation differences, the presence of z‐polarized light, and electric field gradients that give rise to new spectroscopic selection rules. We also discuss some of the recent advances in near‐field scanning optical microscopy (NSOM) and their positive impact on nano‐Raman spectroscopy. In particular, progress has been made in fabricating better probes, both apertured and apertureless, for NSOM, resulting in larger signal levels important for Raman spectroscopy. Larger signals result in shorter imaging times, the ability to achieve higher resolution and broader applicability of the technique. Copyright © 2003 John Wiley & Sons, Ltd.
Near‐field scanning Raman microscopy using apertureless probes
Authors: Sun W. X. , Shen Z. X. 
Published: September 2003

AbstractWe describe an apertureless near‐field scanning Raman microscope in reflection geometry developed by integrating a near‐field scanning optical microscope and a Raman spectrometer. This set‐up offers some unique features that make it applicable to more samples. The fabrication of the metal tips is also explained in detail. Near‐field Raman mappings have been realized on real silicon devices for the first time. The results illustrate the capability of our near‐field Raman microscope in 2D Raman imaging. The apertureless configuration is a breakthrough to the limitation set by the low optical throughput of metal‐coated optical fiber tips, reducing drastically the integration time for Raman spectra. The reflection scattering geometry makes the system applicable to any samples without preparation. Copyright © 2003 John Wiley & Sons, Ltd.
Cell wall composition of vascular and parenchyma tissues in broccoli stems
Authors: Müller S , Jardine WG , Evans BW , Viëtor RJ , Snape CE , Jarvis MC 
Published: September 2003

AbstractBroccoli stems can become tough and stringy owing to excessive development of the vascular ring. Thickened cell walls from the vascular ring were isolated and their composition was determined. They were derived principally from anatomically recognisable xylem vessels, fibres and tracheids but contained an assemblage of polysaccharides typical of primary cell walls. Their pectin content was particularly high and they contained only 6% lignin as estimated by solid state 13C NMR spectroscopy. They did not differ markedly in composition from parenchyma cell walls within the same stems. Thus, despite their thickness and anatomical appearance, these cell walls resembled the walls of non‐woody cells in their polymer composition. Copyright © 2003 Society of Chemical Industry
A chromametric method for the rapid assessment of deep frying oil quality
Authors: Xu Xin‐Qing 
Published: September 2003

AbstractA rapid chromametric method was developed for the assessment of deep frying oil quality based on the strong correlation between colour index and total polar compounds in deep frying oil. Colour indices of frying oil samples, measured by chromameter, decreased significantly during frying and were strongly correlated with frying time (r ≥ 0.95, p < 0.001). Colour indices of a set of oil samples taken from 0 to 80 h of deep frying were also significantly correlated with total polar compounds of the same samples determined using the official method of the American Oil Chemists' Society (r = 0.96, p < 0.001). The equation for conversion of the colour index (x) to the content of total polar compounds (y) in an oil sample is y = 0.0174x2 − 2.9506x + 124.34. In addition, colour indices of 10 different types of frying oils were strongly correlated with the corresponding contents of total polar compounds in the oils with samples taken from 0 to 80 h of deep frying in duplicate (r = 0.95, p < 0.001, n = 220). The results of colour index analyses agreed well with the results of chemical and sensory analyses of the frying oils tested. This chromametric method is rapid, convenient and reliable. Copyright © 2003 Society of Chemical Industry
Structural features of arabinoxylans from Sonalika variety of wheat: comparison between whole wheat flour and wheat bran
Authors: Nandini CD , Salimath PV 
Published: September 2003

AbstractArabinoxylans (AX) were extracted from Sonalika variety of wheat (whole wheat flour and wheat bran) with barium hydroxide and sodium hydroxide and purified by a combination of alcohol precipitation and glucoamylase digestion. Structural features of purified AX were elucidated by methylation analysis,13C NMR, FT‐IR, periodate oxidation and optical rotation measurements. The AX showed a backbone of xylose residues with β(1–4) linkages and were branched mainly through O‐3 of xylose residues. Completely branched xylosyl residues were also present. Copyright © 2003 Society of Chemical Industry
Aspergillus species from section Flavi isolated from soil at planting and harvest time in peanut‐growing regions of Argentina
Authors: Barros Germán , Torres Adriana , Palacio Gabriela , Chulze Sofía 
Published: September 2003

AbstractAspergillus species from section Flavi were isolated from soil samples in three peanut‐growing regions of Córdoba Province, Argentina. The samples were collected during the planting and harvest periods. Both total fungal population and Aspergillus species from section Flavi showed no significant differences between planting and harvest time in two of the regions evaluated. Only in one region were there significant differences in cfu g−1 of total fungal population and Aspergillus species from section Flavi. A flavus was the dominant species isolated in all three localities during the planting and harvest periods. There were significant differences (p < 0.05) in the ratio of toxigenic and atoxigenic strains dependent on the period and the region evaluated. In one region, higher frequencies of toxigenic A flavus and A parasiticus in soil were found and a high contamination level of aflatoxins was detected in peanut seeds. Copyright © 2003 Society of Chemical Industry
Texture changes in fresh cut celery during refrigerated storage
Authors: Viña Sonia Z , Chaves Alicia R 
Published: September 2003

AbstractThe effect of refrigerated storage temperature (0 or 10 °C) on variations in texture and lignin content of minimally processed celery was assessed. In addition, the evolution of soluble phenols was studied, as well as changes in other quality parameters, namely weight loss, surface colour and contents of chlorophyll and free sugars. To this end, celery cuts were packaged on PVC film‐covered polystyrene trays. The maximum shear force required to cut the strips transversally followed a similar tendency during storage at both temperatures tested. Increases in lignin content were observed which could be related to corresponding texture increases during the first few days in cold storage. There was no evidence that lignification occurred by a cicatrix‐forming process in the wounds caused during cutting. Copyright © 2003 Society of Chemical Industry
Can grafting in tomato plants strengthen resistance to thermal stress?
Authors: Rivero Rosa M , Ruiz Juan M , Romero Luis 
Published: September 2003

AbstractGrafted and non‐grafted tomato plants were grown at 25 and 35 °C for 30 days. In tomato leaves we analysed total phenols, o‐diphenols, enzymatic activities (PAL, PPO and GPX) and dry weight. Our results indicate that heat stress in both grafted and non‐grafted tomato plants occurred at 35 °C and resulted in (1) increased PAL activity, (2) increased total phenols and o‐diphenols, (3) decreased PPO and GPX activities and (4) decreased dry weight. These results show that high temperature induces the accumulation of phenolics in tomato plants by activating their biosynthesis as well as inhibiting their oxidation. However, the impact of high‐temperature stress was smaller in grafted than in non‐grafted tomato plants. This indicates that grafted plants have a higher degree of resistance against thermal stress if the rootstock is more resistant to thermal stress. Copyright © 2003 Society of Chemical Industry
Effects of Azadirachta excelsa on feeding behaviour, body weight and mortality of Crocidolomia binotalis Zeller (Lepidoptera: Pyralidae)
Authors: Teik Ng Lean , Mun Yuen Pak , Hong Loke Wai , Abdul Kadir Azizol 
Published: September 2003

AbstractWe investigated the effects of methanolic extracts of Azadirachta excelsa wood (SWE) at concentrations of 5, 10 and 20 g l−1 against Crocidolomia binotalis. Second instars were fed a diet of cabbage leaves treated with SWE or were contacted topically with SWE. The results indicated that SWE produced significant (p < 0.05) antifeedant and contact toxicity effects. However, among the different treatments, a lesser effect on pupal weight was noted in the contact toxicity test. In most instances, untreated leaves were severely damaged, whereas leaves treated with SWE were not attacked or were only slightly damaged. Although both methods of SWE treatment caused a significantly high mortality rate, there was no difference in dose response in the range studied. Thus SWE at a concentration of 5 g l−1 was shown to be as active as that at 20 g l−1. The results indicate that SWE is a potent antifeedant and also has toxicity against C binotalis. Copyright © 2003 Society of Chemical Industry
Discrimination of cucumber cultivars using a multiple‐point sheet sensor to measure biting force
Authors: Dan Haruka , Okuhara Kazutake , Kohyama Kaoru 
Published: September 2003

AbstractTo define the textural differences among three cucumber cultivars, we combined two different mechanical measurements: a direct measurement of mastication force using a multiple‐point sheet sensor (MSS), and a uniaxial compression test. For mastication force measurement, subjects bit a sample placed on the sheet sensor with their upper and lower incisors. During a single bite, masticatory force was measured using a computerised MSS device called the ISCAN system with a TSCAN sheet sensor. Values of maximum bite force, the time at which maximum bite force appeared, area under the force–time curve, contact area and maximum pressure point for one cultivar were significantly higher than those for the other two. For all the parameters, lower values corresponded to crispness and higher values to toughness. Overall tendencies were the same in the compression test, though the compression test tends to yield smaller standard deviations. The MSS masticatory test is suitable for analysing masticatory properties with respect to each individual, while the instrument test is suitable for analysing physical properties inherent in each sample. Combination of the actual mastication test performed in the human oral cavity and conventional mechanical tests provides the most reliable objective analysis of food texture. Copyright © 2003 Society of Chemical Industry
Bouillon cubes: assessment of the state of degradation of the lipid fraction
Authors: Caponio Francesco , Gomes Tommaso , Bilancia Maria Teresa 
Published: September 2003

AbstractAn experimental investigation was carried out to assess the oxidative and hydrolytic quality of the lipid fraction of bouillon cubes. Besides the routine analyses prescribed by EC regulations, determinations of fatty acid composition and unsaturated fatty acid trans isomers were also performed. From the lipid fraction extracted from each cube, polar compounds were separated by silica gel column chromatography and then submitted to HPSEC (high‐performance size exclusion chromatography) analysis to determine the classes of substances deriving from oxidation, polymerisation and hydrolysis of triglycerides. The data obtained showed that the determination of trans isomers and the subsequent HPSEC analysis of polar compounds enable one to ascertain the actual degradation of the lipid fraction of such food preparations. The degree of degradation of the lipid fraction of bouillon cubes was similar to that normally found in olive‐pomace oil, which is the poorest olive oil commercial class. Finally, the contents of trans isomers and triglyceride oligopolymers are shown to be significantly higher in hydrogenated than in non‐hydrogenated vegetable fats. Copyright © 2003 Society of Chemical Industry
Analytical composition and rumen degradability of isogenic and transgenic corn varieties
Authors: Rossi F , Moschini M , Fiorentini L , Masoero F , Piva G 
Published: September 2003

AbstractTwo different corn cultivars were compared with their genetically modified counterparts containing the gene coding for the Cry1A(b) protein of Bacillus thuringiensis (Bt). There were no analytical differences between the conventional and transgenic genotype kernels, whereas stovers from Bt+ plants had higher sugar (148.3 g kg−1 versus 115.9 g kg−1; P < 0.01) and lower NDF (592.7 g kg−1 versus 631.5 g kg−1; P < 0.05) contents than Bt− maize. A comparison of the amino acid profiles showed higher phenylalanine content in kernels from the Bt+ plants (49.1 g kg−1 vs 47.8 g kg−1; P < 0.05) which was, however, not reflected in the protein content. The initial dry matter rumen degradability of the isogenic kernels was higher than that of Bt+ varieties (569.5 g kg−1 vs 543.7 g kg−1; P < 0.05), whereas the lower fibre content increased the dry matter (548.6 g kg−1 vs 526.6 g kg−1; P < 0.01) and protein (695.6 g kg−1 vs 647.9 g kg−1; P < 0.01) degradability after 24 h of incubation in stovers from Bt+ plants. The NDF degradability was higher in Bt− corn varieties because of the higher proportion of hemicellulose in the total fibre. Copyright © 2003 Society of Chemical Industry
Uptake of fluoride by tea plant (Camellia sinensis L) and the impact of aluminium
Authors: Ruan Jianyun , Ma Lifeng , Shi Yuanzhi , Han Wenyan 
Published: September 2003

AbstractTea plant (Camellia sinensis L) accumulates large amounts of fluoride in mature leaves from soils of normal fluoride availabilities, but the properties of fluoride absorption by this plant species are not well understood. The present study examined the characteristic of fluoride uptake by tea plants and the impact of Al with solution and soil experiments. The results showed that the fluoride taken up by tea plants was largely and readily transported, in particular to the leaves. The fluoride in leaves increased linearly with fluoride concentrations in the uptake solution (R2 = 0.75, P < 0.001) or in the soil (R2 = 0.88, P < 0.001), whereas those in root and stem were only marginally influenced. Including Al in solution or adding Al to the soil apparently increased the uptake and translocation of fluoride to the leaves. The concentrations of fluoride in the leaves were significantly (P < 0.05) increased by 19.1% or 37.7% when 18.5 µmol l−1 Al or 74.1 µmol l−1 Al respectively was included in the uptake solution, compared with the control without Al during an uptake period of 22 h. Similarly, Al application (100 mg kg−1) to soil led to significantly higher fluoride concentrations in mature leaves and new shoots (one bud with three leaves). By contrast, the concentrations of Al in leaves in solution and soil experiments were not affected by fluoride and Al treatments. Nevertheless, higher Al concentrations after Al and fluoride additions were observed in the new shoots in soil experiments. Copyright © 2003 Society of Chemical Industry
Supercritical CO2 extraction of Chilean hop (Humulus lupulus) ecotypes
Authors: del Valle José M , Rivera Oscar , Teuber Osvaldo , Palma M Teresa 
Published: September 2003

AbstractHops (Humulus lupulus L) have very stringent requirements of diurnal light hours during flowering. Thus, the beer industry is permanently assessing new agricultural land to grow hops, southern Chile being an excellent candidate for their introduction. Supercritical carbon dioxide extraction procedures were implemented to assess Chilean hop ecotypes. Based on results of a preliminary study with commercial samples (cv Nugget), 200 bar and 40 °C were selected as extraction conditions. Very limited increases in extraction rate were observed when applying pressures >200 bar; such pressures did not speed up the extraction of α‐acids (bitter flavor principles), but rather increased the co‐extraction of undesirable compounds (hard resins and chlorophyll pigments). On the other hand, the effects of retrograde condensation phenomena were just starting to subside at 200 bar, and thermal damage of samples could increase at >40 °C. Ground cone samples of five local hop ecotypes, originating from Osorno, La Junta, Coyhaique and Elizalde Lake, were subsequently tested. Osorno exhibited a higher yield (65 g kg−1 oleoresin/substrate) than other Chilean ecotypes. Moreover, Osorno extract had a light yellowish color, as well as a higher content of bitter flavors (157 g kg−1 α‐acid/extract) and 1.5–7.1 times more representative aroma compounds than extracts of the other ecotypes. However, all these indicators were very low compared with the commercial Nugget sample (134 g kg−1 oleoresin/substrate, 383 g kg−1 α‐acid/extract, 14 times more aroma compounds than Osorno ecotype). Copyright © 2003 Society of Chemical Industry