bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vibrational spectroscopic investigations and density functional theory calculations on trans‐diaquabis(picolinato)zinc(II) dihydrate complex
Authors: Sinha P. K. , Bolboaca M. , Schlücker S. , Popp J. , Kiefer W. 
Published: April 2003

AbstractFT‐Raman and FT‐infrared spectra of pyridine‐2‐carboxylic acid (picolinic acid) and its corresponding trans‐diaquabis(picolinato)zinc(II) dihydrate complex were recorded. Density functional theory was used in order to calculate the optimized geometries and harmonic vibrational wavenumbers of the coordination compound and its isolated ligand. The calculation for the complex was performed under Ci symmetry constraints and all 93 vibrational modes were classified as either Raman active (ag symmetry) or infrared active (au symmetry). The assignment of the characteristic bands was performed by using the calculated harmonic wavenumbers and their Raman intensities. The agreement between the calculated and experimental values of both the structural parameters and the vibrational modes was fairly good. The influence of metal coordination on the picolinic acid was monitored by the wavenumber shift of certain marker bands and the appearance of new vibrational bands.Copyright © 2003 John Wiley & Sons, Ltd.
Fourier transform Raman spectral reconstruction of inorganic lead mixtures using a novel band‐target entropy minimization (BTEM) method
Authors: Ong Lih Ren , Widjaja Effendi , Stanforth Robert , Garland Marc 
Published: April 2003

AbstractA novel method of band‐target entropy minimization (BTEM) was successfully applied to spectral reconstruction of two sets of solid mixtures containing different species of lead compounds which were measured using Fourier transform (FT) Raman spectroscopy. As a first step, bands or regions containing significant spectral features in the vector‐space decomposition of the observations were identified and selected to untangle the superposition of the pure component spectra. The targeted bands were retained and the pure component spectra of lead oxide and lead arsenate, both common in the two sets, lead carbonate (in Set 1) and lead hydroxide and pyromorphite (both in Set 2) were all readily recovered. The BTEM algorithm results in (i) a fast computational speed since one spectrum is generated at a time and (ii) high‐quality spectral reconstructions. The algorithm allows maximum chemical information recovery from experimental data by utilizing more vectors in the vector‐space decomposition than the actual number of species present in the observations. The results further indicate that the BTEM algorithm is viable for detecting species at low concentrations or which have low intensity. Most important, there is no recourse to any libraries and no a priori information is required for spectral reconstruction. This approach holds promise for the rapid analysis and identification of solid mixtures by FT Raman spectroscopy. Copyright © 2003 John Wiley & Sons, Ltd.
Photoreduction of iron protoporphyrin IX chloride in ionic detergent micelles probed by resonance Raman spectroscopy
Authors: Shantha P. K. , Saini G. S. S. , Thanga H. H. , Verma A. L. 
Published: April 2003

AbstractPhotoinduced electron transfer from axially coordinated electron donor to hemin in aqueous cetyltrimethylammonium bromide and sodium dodecyl sulfate micelles under various pH conditions with and without hindered/unhindered imidazoles was investigated. Photoreduction of hemin in the former micelles under anaerobic conditions in alkaline and neutral aqueous medium takes place by electron transfer from axially coordinated hydroxyl ion to an FeIII atom in the photoexcited state. In sodium dodecyl sulfate micelles, hemin is photoreducible only at alkaline pH and under anaerobic conditions in the presence of alcohol and imidazoles. Photoreduction appears to depend on the immediate local environment of hemin in the micelles. Copyright © 2003 John Wiley & Sons, Ltd.
Spectra and structure of silicon‐containing compounds. XXXVI—Raman and infrared spectra, conformational stability, ab initio calculations and vibrational assignment of ethyldibromosilane
Authors: Guirgis Gamil A. , Klaboe Peter , Shen Shiyu , Powell David L. , Gruodis Alytis , Aleksa Valdemaras , Nielsen C. J. , Tao Jing , Zheng Chao , Durig James R. 
Published: April 2003

AbstractThe Raman spectrum of liquid ethyldibromosilane, CH3CH2SiHBr2, was recorded at various temperatures between 298 and 218 K, and the spectrum of the crystal was obtained at 210 K from a sample sealed in a capillary. Additional spectra of the amorphous and annealed crystals, which were deposited on a copper finger cooled with boiling liquid nitrogen, were recorded. The infrared spectra were recorded of the vapor and amorphous and crystalline solid in the range 4000–50 cm−1 and mid‐infrared spectra isolated at 4.8 K in argon and nitrogen matrices were also observed. These vibrational spectra show that two conformers, anti and gauche, are present in the vapor and in the liquid, but only the anti conformer remains in the crystalline solid. Three conformer pairs in the Raman spectrum of the liquid phase were used to obtain the enthalpy difference, which gave an average value of 128 ± 17 cm−1 (1.53 ± 0.2 kJ mol−1) with the anti form lower in energy. At ambient temperature it is estimated that there is 52 ± 2% of the gauche conformer present in the liquid. The optimized geometries, infrared and Raman intensities, and scaled vibrational wavenumbers for the anti and gauche conformers were obtained from ab initio MP2/6–31G(d) calculations with full electron correlation. The conformational energy difference was also obtained from ab initio MP2/6–311 + G(d,p) calculations which gave a predicted energy difference of 97 cm−1 with the anti form the conformer of lower energy. These spectroscopic and theoretical results are discussed and compared with the corresponding quantities for some similar molecules. Copyright © 2003 John Wiley & Sons, Ltd.
Adsorption of 4,4′‐biphenyl diisocyanide on gold nanoparticle surfaces investigated by surface‐enhanced Raman scattering
Authors: Joo Sang‐Woo , Kim Wan‐Joong , Yoon Wan Soo , Choi Insung S. 
Published: April 2003

AbstractWe investigated the spectral features of the ν(NC) bands when 4,4′‐biphenyl diisocyanide (BPDNC) is adsorbed on gold nanoparticle surfaces by surface‐enhanced Raman scattering (SERS). The mode of adsorption of BPDNC on gold nanoparticles was found to change with the bulk concentration. At low concentrations of BPDNC, only the ν(NC)bound band was conspicuous at ∼2185 cm−1 and the free NC stretching band was barely detected in the SERS spectra. When the bulk concentration was increased, the ν(NC)free band became prominent at ∼2123 cm−1. BPDNC was assumed to bridge two different gold particles at low concentrations, but as the concentration was increased, the bridge appeared to be broken and bonded to the gold particle only via one of the two isocyanide groups. On the basis of the electromagnetic surface selection rule, we attempted to explain the orientation of the adsorbate on Au surfaces by determining the relative enhancement factor of each vibrational band. Copyright © 2003 John Wiley & Sons, Ltd.
Raman and DFT study of the vibrational properties of some para‐substituted benzohydroxamic acids: towards an interpretation of SER spectra
Authors: Blajiev Orlin , Hubin Annick , Tielens Frederik , Geerlings Paul 
Published: April 2003

AbstractThe vibrational properties of p‐chloro‐, p‐methoxy‐ and p‐nitrobenzohydroxamic acids (BHA) and of the unsubstituted BHA were investigated and the spectra were assigned. The assignment was made on the basis of the experimental information available about the Raman peaks of mono‐ and disubstituted benzenes and the procedure was greatly facilitated by the data obtained from high‐level DFT quantum‐chemical calculations. In order to support an intended assignment of the SER spectra of BHA on copper, the molecular electrostatic maps and Fukui functions were derived from ab initio calculations. Both quantum‐chemical descriptors were shown to provide similar information about the possible BHA molecule–copper surface interaction sites. Copyright © 2003 John Wiley & Sons, Ltd.
Pink pigment optimization by resonance Raman spectroscopy
Authors: Faurel Xavier , Vanderperre Anne , Colomban Philippe 
Published: April 2003

AbstractThe chromium‐doped tin‐based sphene (malayite) pink pigment was synthesized in different ways in the form of powder and single crystals. The usefulness of resonance Raman spectroscopy as a fast characterization technique for such ceramic pigments was evaluated with emphasis on the colour shift induced by second phases. Copyright © 2003 John Wiley & Sons, Ltd.
Raman spectroscopic characteristics of phthalocyanine and naphthalocyanine in sandwich‐type phthalocyaninato and porphyrinato rare earth complexes. Part 5—Raman spectroscopic characteristics of naphthalocyanine in mixed [tetrakis(4‐tert‐butylphenyl)porphyrinato] (naphthalocyaninato) rare earth double‐deckers
Authors: Sun Xuan , Rintoul Llew , Bian Yongzhong , Arnold Dennis P. , Wang Rongming , Jiang Jianzhuang 
Published: April 2003

AbstractRaman spectra were recorded in the range 400–1800 cm−1 for a series of 15 mixed [tetrakis(4‐tert‐butylphenyl)porphyrinato](2,3‐naphthalocyaninato) rare earth double‐deckers M(TBPP)(Nc) (M = Y; La–Lu except Pm) using laser excitation at 632.8 and 785 nm. Comparisons with bis(naphthalocyaninato) rare earth counterparts reveal that the vibrations of the metallonaphthalocyanine M(Nc) fragment dominate the Raman features of M(TBPP)(Nc). When excited with radiation of 632.8 nm, the most intense vibration appears at about 1595 cm−1, due to the naphthalene stretching. These complexes exhibit the marker Raman band for Nc•− as a medium‐intense band in the range 1496–1507 cm−1, attributed to the coupling of pyrrole and aza stretching, while the marker Raman band of Nc2− in intermediate‐valence Ce(TBPP)(Nc) appears as a strong band at 1493 cm−1 and is due to the isoindole stretchings. By contrast, when excited with radiation of 785 nm that is in close resonance with the main Q absorption band of the naphthalocyanine ligand, the ring radial vibrations at ca 680 and 735 cm−1 for MIII(TBPP)(Nc) are selectively intensified and are the most intense bands. For the cerium double‐decker, the most intense vibration also acting as the marker Raman band of Nc2− appears at 1497 cm−1 with contributions from both pyrrole CC and aza CN stretches. The same vibrational modes show weak to medium intensity scattering at 1506–1509 cm−1 for MIII(TBPP)(Nc) and this is the marker Raman band of Nc•− when thus excited. The scatterings due to the Nc breathings, ring radial vibration, aza group stretchings, naphthalene stretchings, benzoisoindole stretchings and the coupling of pyrrole CC and aza CN stretchings in MIII(TBPP)(Nc) are all slightly blue shifted along with the decrease in rare earth ionic radius, confirming the effects of increased ring–ring interactions on the Raman characteristics of naphthalocyanine in the mixed ring double‐deckers. Copyright © 2003 John Wiley & Sons, Ltd.
Diamond as pressure sensor in high‐pressure Raman spectroscopy using sapphire and other gem anvil cells
Authors: Baonza Valentín García , Taravillo Mercedes , Arencibia Amaya , Cáceres Mercedes , Núñez Javier 
Published: April 2003

AbstractWe propose a new Raman pressure scale based on the shift with pressure of the fundamental Raman band of micrometer‐sized diamonds. First, we confirmed that the pressure slope of the triply degenerate diamond phonon behaves in a similar fashion to that of the bulk. Our measurements were calibrated Raman against the Sm:YAG fluorescence pressure scale up to 5 GPa using a gasketed sapphire anvil cell. The most relevant features regarding the design of the anvil cell are briefly outlined. Measurements were performed under hydrostatic conditions using 4 : 1 methanol–ethanol as pressure‐transmitting medium. The calibration pressures according to the relationship p(GPa) = 0.356[ν(cm−1) − 1332.3] are considered to be accurate within about 0.1 GPa. The convenience of using micrometer‐sized diamonds as pressure sensors in Raman studies using gem anvil devices is demonstrated with several examples. Copyright © 2003 John Wiley & Sons, Ltd.
High‐pressure Raman and infrared spectroscopy of polyacetylene
Authors: Balzaretti Naira Maria , Perottoni Cláudio Antônio , da Jornada João Alziro Herz 
Published: April 2003

AbstractA systematic study of the high‐pressure (HP) effect on the Raman and infrared (IR) spectra of the cis and trans isomers of polyacetylene (PA) is presented. The experiments were performed in a diamond anvil cell (DAC) up to 9.6 GPa. The pressure‐dependent Raman resonance effect observed for cis‐PA was used to estimate the pressure dependence of the energy gap (Eg) for this isomer. The calculated pressure derivative at zero pressure, dEg/dP = −0.12 eV GPa−1, is the same as that for the trans isomer, estimated from previous results for optical absorption measurements. This is consistent with the idea that the relevant effect of moderated pressures on the PA structure should be the reduction of the interchain distance, which leads to increased interchain coupling that would affect both isomers in a similar way. Furthermore, the IR spectra indicated the onset of structural modifications on both isomers at pressures above 5 GPa. These structural transitions are reversible in the case of trans‐PA and irreversible for cis‐PA. Copyright © 2003 John Wiley & Sons, Ltd.
Freezing/defrosting/frying of sardine fillets. Influence of slow and quick defrosting on protein quality
Authors: García‐Arias M Trinidad , Alvarez‐Pontes Esther , García‐Fernández M Camino , Sánchez‐Muniz Francisco J 
Published: April 2003

AbstractThe effect of sequential freezing/defrosting/frying on protein quality is not well known. With this in mind, fillets of fresh sardine were stored frozen, then thawed, either conventionally at 4 °C in a refrigerator or with the use of a microwave oven, and subsequently deep‐fried. Proximate and amino acid compositions, protein solubility in sodium dodecyl sulphate/β‐mercaptoethanol (SDS/β‐ME), total SH group content and amino acid chemical score were determined. The lowest protein concentration was observed in frozen/4 °C‐thawed sardines (CR), whilst the lowest fat content was found in both fresh/fried sardines (F) and 4 °C‐thawed/fried sardines (CF). Every step of each process studied caused a decrease in cyst(e)ine; the most important loss was recorded in CF samples and in frozen sardines fried without defrosting (Fro‐F). The lowest solubility in SDS/β‐ME and the lowest total SH group content were observed for Fro‐F samples and microwave‐thawed/fried sardines (MF). On the other hand, the lowest chemical score was found for Fro‐F, CF and MF samples. Although weight loss and proximate composition seemed to change less when defrosting sardine fillets using a microwave oven rather than at 4 °C, the results for SDS/β‐ME solubility and total SH group content suggest that a slow defrosting process (refrigerator at 4 °C) is preferable to a much quicker process (microwave oven) for thawing frozen sardine fillets before frying. Copyright © 2003 Society of Chemical Industry
Olive oil extractability index as a parameter for olive cultivar characterisation
Authors: Beltrán Gabriel , Uceda Marino , Jiménez Antonio , Aguilera Maria P 
Published: April 2003

AbstractExtractability, when applied to the olive oil extraction process is defined as the percentage of oil extracted from the total oil content of the fruit. In this work, extractability index (EI), a new parameter determined in a laboratory oil mill, has been studied for 24 olive (Olea europaea L) cultivars from the Olive Germplasm Bank Collection of Mengibar (Spain). In order to evaluate the genetic variability of this new parameter, the influence of cultivar and tree on EI variability has been analysed in olive fruits collected at the same ripening index. The results indicate that cultivar is the most important variation source. Thus olive oil extractability depends on extraction process variables and cultivar. Extractability index could be used together with pulp oil content (on a dry matter basis) as a parameter for olive cultivar characterisation and selection for breeding projects. Copyright © 2003 Society of Chemical Industry
Oxidative effects in uninfected tissue in leaves of French bean (Phaseolus vulgaris) containing soft rots caused by Botrytis cinerea
Authors: Muckenschnabel Ingo , Schulze Gronover Christian , Deighton Nigel , Goodman Bernard A , Lyon Gary D , Stewart Derek , Williamson Brian 
Published: April 2003

AbstractSeveral markers of oxidative processes have been measured in leaves of Phaseolus vulgaris infected with Botrytis cinerea, with the specific objective of investigating changes induced by this necrotrophic pathogen in tissue remote from the lesion. There was a progressive decrease with time in the contents of ascorbic acid (AA) in apparently healthy tissues from infected plants and non‐inoculated plants grown under identical high‐humidity conditions (abiotically stressed controls), and for periods >48 h this decrease was greater in the infected plants. This decline in AA content was accompanied by an elevation in the intensity of the electron paramagnetic resonance (EPR) signal from adducts of the spin trap α‐(4‐pyridyl‐1‐oxide)‐N‐t‐butylnitrone (POBN), a destabilisation of the (monodehydro) ascorbate radical (Asc·) signal in the presence of POBN, and an increase in the ratio of Asc· to AA in samples studied in the absence of the spin trap. These results are consistent with a shift in redox status to more oxidising conditions in apparently healthy tissue of infected plants and indicate the prevalence of chemical processes that are distinctly different from those in uninfected plants. However, no differences in lipid peroxidation products or the single‐peak free radical and Fe(III) (g = 4.27) EPR signals were observed between these tissues distant from the lesions and those from abiotically stressed controls. In addition, the pathogen‐derived sesquiterpene toxin botrydial and a second Mn(II) EPR signal, both of which are associated with Botrytis infection, were not detected in these ‘apparently healthy’ tissues. Copyright © 2003 Society of Chemical Industry
Effect of age of regrowth on chemical composition of chaya (Cnidoscolus aconitifolius) leaves
Authors: Sarmiento‐Franco Luis , Sandoval‐Castro Carlos A , McNab Jim M , Quijano‐Cervera Rosario , Reyes‐Ramirez Raúl R 
Published: April 2003

AbstractThe chemical composition of chaya (Cnidoscolus spp) leaves, as a promissory edible tropical shrub for both humans and animals was evaluated. The chemical composition of C aconitifolius did not differ significantly with age of regrowth, with the exception of ether extractives and the oxalic acid content. Galactose, glucose and xylose were the most important sugars found in the insoluble fraction and, galactose and uronic acid were the main components in the soluble portion of non‐starch polysaccharides (NSP). There was a total content of 197.2 g kg−1 NSP, of which 68.72 and 31.26% corresponded to the insoluble and soluble components respectively. The amino acid composition of C aconitifolius ranged from 0.416 for lysine to 0.641 for valine relative to their contents in soyabean meal. Nevertheless, without exception, the concentrations of all the essential amino acids in C aconitifolius were higher than the corresponding values in alfalfa, a fibrous foodstuff widely acceptable in diets for farm animals. Copyright © 2003 Society of Chemical Industry
Amino acid profiles and protein quality of cooked cassava leaves or ‘saka‐saka’
Authors: Diasolua Ngudi Delphin , Kuo Yu‐Haey , Lambein Fernand 
Published: April 2003

AbstractCassava (Manihot esculenta Crantz) leaves form the main source of protein in a diet consisting of processed cassava roots as sole staple food in konzo‐affected areas of the Democratic Republic of Congo. Pounded cassava leaves were hydrolysed and analysed by HPLC before and after cooking to assess amino acid profiles and protein quality. An average of about 58% loss of total protein content was observed in five different cooked samples. The protein content in cassava leaves was high, an average of 285.9 g kg−1 dry weight in the raw and 119.2 g kg−1 dry weight in the cooked samples, but of poor quality, with sulphur amino acids as the most limiting amino acids. Lysine and leucine were also limiting amino acids in some of the raw samples. Lysine, histidine, leucine and isoleucine were limiting amino acids in the cooked samples besides the sulphur amino acids. The consumption of cassava leaves does not compensate the dietary deficiency of sulphur amino acids in the roots that are the staple food in konzo‐affected areas. Sulphur amino acids are essential for detoxification of the residual cyanogens remaining in insufficiently processed cassava roots. Cereals and legumes, as sources of sulphur amino acids and lysine respectively, should be promoted as part of the diet in those areas to prevent the paralytic neuro‐toxico‐nutritional disease konzo among the poor population. Copyright © 2003 Society of Chemical Industry
Compositional and degradative changes during the manufacture of dry‐cured ‘lacón’
Authors: Lorenzo José M , Prieto Bernardo , Carballo Javier , Franco Inmaculada 
Published: April 2003

AbstractThe gross and mineral composition, the main physicochemical parameters, the protein extractability and the proteolytic (nitrogen fractions and free amino acids) and lipolytic (acidity index and free fatty acids) changes were studied throughout the manufacturing process of five batches of dry‐cured ‘lacón’, a traditional Spanish meat product made from the fore‐ham of the pig following a similar technological process to that of dry‐cured ham. The main compositional characteristics of this product are the high NaCl content and the low moisture content at the end of the curing process. The pH remained fairly stable (around 6) throughout the whole process and a fall inawwas observed, reaching very low (0.767 ± 0.052) final average values. It was noted that 76% of the sarcoplasmic and 83% of the myofibrillar proteins became insoluble during the manufacturing process. The values of the different nitrogen fractions increased in a significant manner during manufacture, reaching low final values that indicate that ‘lacón’ undergoes a low level of proteolysis in comparison with other products manufactured by similar technologies. The high NaCl content and the intense dehydration suffered during the manufacturing process appear to be the principal causes of this reduced protein degradation. In accordance with the limited increase in the α‐amino acidic nitrogen during ripening, the total free amino acid content increased slightly but significantly from average values of 4371 mg kg−1dry matter in fresh pieces to average values of 13 020 mg kg−1dry matter in pieces at the end of the ripening process. The profile of free amino acids in the final product was similar to that observed by other authors in dry‐cured ham. The acidity of the fat increased by a factor of five. The final average values (49.9 g oleic acid kg−1) were lower than those determined in dry‐cured ham, which indicates that ‘lacón’ undergoes less lipolysis during the ripening process than dry‐cured ham. C18 : 1, C18 : 2 and C16 were the most intensively released fatty acids during curing. The profile of free fatty acids in the end product was in agreement with that observed by other authors in dry‐cured ham. Copyright © 2003 Society of Chemical Industry