bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of the reaction products of flavonols with 2,2‐diphenyl‐1‐picrylhydrazyl using liquid chromatography coupled with negative electrospray ionization tandem mass spectrometry
Authors: Hvattum Erlend , Stenstrøm Yngve , Ekeberg Dag 
Published: December 2004

AbstractThe products obtained after the reaction between flavonols and the stable free radical 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH•) in both methanol and acetonitrile were characterized using liquid chromatography coupled with negative electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) and NMR spectroscopy. The flavonols studied were quercetin, kaempferol and myricetin. In methanol, two reaction products of oxidized quercetin were identified using LC/ESI‐MS/MS and NMR. Quercetin was oxidized through a transfer of two H‐atoms to DPPH• and subsequently incorporated either two CH3OH molecules or one CH3OH‐ and one H2O molecule giving the products 2‐(3,4‐dihydroxyphenyl)‐3,5,7‐trihydroxy‐2,3‐dimethoxy‐2,3‐dihydrochromen‐4‐one and 2‐(3,4‐dihydroxyphenyl)‐3,3,5,7‐tetrahydroxy‐2‐methoxy‐2,3‐dihydrochromen‐4‐one, respectively. LC/ESI‐MS/MS analysis revealed that in methanol, kaempferol and myricetin also gave rise to methoxylated oxidation products similar to that identified for quercetin. Kaempferol, in addition, also exhibited products where a kaempferol radical, obtained by a transfer of one H‐atom to DPPH•, reacted with CH3OH through the addition of CH3O•, yielding two isomeric products. When the reaction took place in acetonitrile, LC/ESI‐MS/MS analysis showed that both quercetin and myricetin formed stable isomeric quinone products obtained by a transfer of two H‐atoms to DPPH•. In contrast, kaempferol formed two isomeric products where a kaempferol radical reacted with H2O through the addition of OH•, i.e. similar to the reaction of kaempferol radicals with CH3OH. Copyright © 2004 John Wiley & Sons, Ltd.
Donor–acceptor properties of isonitriles studied by photoelectron spectroscopy and electron transmission spectroscopy
Authors: Csonka István Pál , Szepes László , Modelli Alberto 
Published: December 2004

AbstractSome alkyl and aryl isonitriles, considered as CO analogue σ‐donor and π‐acceptor ligands in transition metal chemistry, were studied by means of HeI photoelectron spectroscopy and electron transmission spectroscopy, in order to evaluate their donor–acceptor properties from the measured ionization energies (IE) and vertical electron attachment energies (VAE). The investigated molecules were 2‐propyl, 1‐butyl, tert‐butyl, 1‐pentyl, cyclohexyl, 2,6‐dimethylphenyl, 4‐methoxyphenyl and 4‐chorophenyl isonitrile. By interpreting the spectra on the basis of literature data and quantum chemical calculations, the spectral features associated with the molecular orbitals mainly involved in coordination and back‐donation were identified. The results show that the IE (10.62–10.95 eV) of the σ electron pair (nc) responsible for the σ‐donor capability is substantially lower than that of CO. The VAEs of the empty π* orbitals involved in the d/π* back‐donation indicate that aryl isonitriles are better acceptors (VAE <0.3 eV) than their aliphatic counterparts (VAE >2.7 eV). In the case of aryl derivatives, the π‐donor ability could also play some role in metal–ligand bonding (IE 8.74–9.34 eV). Isonitrile coordination characteristics are also compared with those of CO, N2 and CH3CN. Copyright © 2004 John Wiley & Sons, Ltd.
Seasonal to interannual variations of soil moisture measured in Oklahoma
Authors: Illston Bradley G. , Basara Jeffrey B. , Crawford Kenneth C. 
Published: December 2004

AbstractAgriculture is a $2 billion component of the state economy in Oklahoma. As a result, meteorological, climatological, and agricultural communities should benefit from an improved understanding of soil moisture conditions and how those conditions vary spatially and temporally. The Oklahoma Mesonet is an automated observing network that provides real‐time hydrometeorological observations at 115 stations across Oklahoma. In 1996, sensors were installed at 60 Mesonet sites to provide near‐real‐time observations of soil moisture.This study focuses on 6 years of soil moisture data collected between 1997 and 2002 to analyse the annual cycle and temporal characteristics of soil moisture across Oklahoma. The statewide analysis of the annual cycle of soil moisture revealed four distinct soil moisture phases. In addition, the four statewide phases were also observed in each of the nine climate divisions across Oklahoma, although the temporal characteristics of each phase were unique for each division. Further analysis demonstrated that, at shallow soil depths (5 and 25 cm), the spatial variability of soil moisture across Oklahoma was most homogeneous during the winter and spring periods and most heterogeneous during the summer and autumn periods. Conversely, at greater depths (60 and 75 cm), soil moisture was most heterogeneous during the winter period and the most homogeneous during the late spring. Copyright © 2004 Royal Meteorological Society
Temperature trends in South Africa: 1960–2003
Authors: Kruger A. C. , Shongwe S. 
Published: December 2004

AbstractTime series of South African temperatures were investigated for temporal and spatial trends for the period 1960 to 2003. For this purpose a total of 26 climate stations were utilized, with each having sufficient data available and not having undergone major moves or changes in exposure that would influence the homogeneity of their data series. The vast majority, a total of 23 stations, showed positive trends in their annual mean maximum temperature series, 13 of them significant, with trends higher for central stations than those closer to the coast. Annual mean minimum temperatures showed 21 stations having positive trends, with 18 significant. Stations not showing significantly positive trends in annual mean minimum temperatures were mostly situated in the central interior. The annual average temperature data series of 24 of the stations showed positive trends, with 18 of them significant. Trends of mean seasonal temperature showed that temperature trends are not consistent throughout the year, with the average trend for autumn showing a maximum and spring a minimum. Monthly trends of average annual temperatures showed large differences in trend between stations, and for each station between months, but similar tendencies in trend between months were found to exist for stations close by and also for groups of stations on a regional basis. Trends in diurnal temperature range are almost equally divided between positive and negative, with the positive trends in the central interior mainly being caused by large positive trends in maximum temperature. It is also shown that, in general, days and nights with relatively high temperatures have increased, while days and nights with relatively low temperatures have decreased. The effects of urbanization on temperature trends are investigated, and the conclusion is that most stations regarded as urban stations are still useful for trend analysis; being situated on the outskirts of cities they are, therefore, not substantially influenced by the urban heat island. El Niño and La Niña events do not seem to play a significant role in the increasing temperatures observed. Copyright © 2004 Royal Meteorological Society
Trends in precipitation on the wettest days of the year across the contiguous USA
Authors: Michaels Patrick J. , Knappenberger Paul C. , Frauenfeld Oliver W. , Davis Robert E. 
Published: December 2004

AbstractOver the course of the 20th century, average annual precipitation for the contiguous USA has increased by nearly 10%. This increase has been described as being dominated by ‘disproportionate’ increases in extreme precipitation events. However, methodological constraints have confounded detailed interpretation of such results. Here, we briefly describe those limitations and re‐evaluate the nature of the observed precipitation changes using a method that allows for a more accurate examination of changes in the proportion of precipitation delivered in extreme daily events. We focus our analysis only on the trends in precipitation on the 10 wettest days of the year and compare the trends observed on those days with the trend in overall precipitation. When averaged across the USA, we find that the precipitation trends on the 10 wettest days of the year are not significantly different from the trend in total overall precipitation. On a regional level, in the northeast and southeast there is some evidence that the rate of precipitation increase on the wettest days exceeds that of total precipitation, whereas in the rest of the country the precipitation on the wettest days is increasing at a rate less than the increase in total precipitation. Copyright © 2004 Royal Meteorological Society
Characterizing regional‐scale variations in monthly and seasonal surface air temperature over Mexico
Authors: Englehart Phil J. , Douglas Arthur V. 
Published: December 2004

AbstractMonthly and seasonal variations in surface air temperature (SAT) over Mexico have not received much research attention, a situation partly reflecting the lack of a coherent historical data set. As a step toward rectifying the data gap, this study outlines the development of a gridded monthly (2.5° × 2.5°lat.–long.) SAT data set (1940–2001) for Mexico. Using the data set, we investigate several basic dimensions of SAT variability. Our analysis demonstrates that much of the variability can be compactly expressed in terms of four regions which are physically plausible with respect to the country's climatology. Not surprisingly, persistence is an important component of regional SAT variability. Evaluated month to month, persistence tends to be greatest during the warm season, whereas across seasons there is evidence for persistence of warm season anomalies into the following cool season, behaviour that is consistent with positive feedback relationships between SAT, rainfall and land surface conditions. The regional time series display longer period variability that is partially linked to the state of the large‐scale, slowly evolving climate modes of the Atlantic multidecadal oscillation and the Pacific decadal oscillation. Analyses are also presented to describe teleconnections between SAT and the El Niño–southern oscillation phenomena, and SAT and other large‐scale atmospheric modes, such as the Pacific North American pattern and the North Atlantic oscillation. Copyright © 2004 Royal Meteorological Society
Honey‐bee products in prevention and/or therapy of murine transplantable tumours
Authors: Oršolić Nada , Terzić Svjetlana , Šver Lidija , Bašić Ivan 
Published: December 2004

AbstractWe investigated the effects of water‐soluble derivative of propolis (WSDP), caffeic acid, honey, royal jelly and bee venom on tumour development and metastasis in murine tumour models. Transplantable murine tumours were used: a spontaneous mammary carcinoma (MCa) and a methylcholanthrene–induced fibrosarcoma (FS) of CBA mouse. Metastases in the lung were generated by injecting 105 or 2 × 105 viable tumour cells intravenously. Tumours in the hind leg were generated by subcutaneous injection of 104 or 105 mammary carcinoma cells. Oral application of WSDP or caffeic acid significantly reduced subcutaneous tumour growth and prolonged survival of mice. Honey also exerted a pronounced antimetastatic effect (p < 0.01 or p < 0.001) when applied before tumour cell inoculation (2 g kg−1 orally once a day for 10 consecutive days). Royal jelly did not affect the formation of metastases when given intraperitoneally or subcutaneously. However, synchronous application of tumour cells and royal jelly intravenously significantly (p < 0.001) inhibited the formation of metastases. When bee venom was injected intratumourally, tumours decreased in size. These findings demonstrated that honey‐bee products given orally or systemically may have an important role controlling tumour growth and metastasis. Copyright © 2004 Society of Chemical Industry
A note on equity ownership and corporate value in Greece
Authors: Karathanassis G.A. , Drakos A.A. 
Published: December 2004

AbstractThis study attempts to investigate whether corporate performance is affected by the ownership structure, using data from companies quoted on the Athens Stock Exchange for the period 1996–1998. Given such an objective, the basic hypothesis examined, is that corporate performance as measured by Tobin's Q ratio is a function of ownership and other control variables. Our econometric approach relies on the use of a combination of time series and cross section data (panel‐data analysis), a procedure that avoids many statistical problems. After examining the role of each identifiable shareholder, we find a positive relationship between institutional investors and corporate performance. Copyright © 2004 John Wiley & Sons, Ltd.
Falls and injuries resulting from falls among patients with Parkinson's disease and other parkinsonian syndromes
Authors: Wielinski Catherine L. , Erickson‐Davis Cordelia , Wichmann Rose , Walde‐Douglas Maria , Parashos Sotirios A. 
Published: December 2004

AbstractWe sought to ascertain frequency, type, risk factors of falling, and resulting injuries among parkinsonian patients. A survey was mailed to all patients treated at our center between 1/1/2000 and 4/30/2002 (N = 1,417). Information was collected on falls within the past 2 years, related injuries, and use of health care services. A total of 1,131 responses (response rate, 79.8%) were received. After the exclusion of nonparkinsonian disorders, statistics for the remaining group (n = 1,092) and predictive statistics for those diagnosed before 1/1/2000 (n = 1,013) were calculated. Outcomes included falls, fractures, injuries, surgery, and related use of health care services. Explanatory variables included sex, age, age at diagnosis, disease duration, atypical parkinsonism, and dementia. Most patients (55.9%) were men; 12.2% had atypical parkinsonism; 12.5% had dementia; median age was 74.7 years; median disease duration was 7 years; 55.9% had at least one fall in the past 2 years; 65.0% of them sustained an injury; 33.0% sustained a fracture; 75.5% of injuries required health care services; 40.6% of fractures required surgery. Older age, atypical parkinsonism, longer disease duration, and dementia were risk factors for falling; female sex and older age were predictors of fractures. Need for health care services after an injury was higher among older patients. Further prospective studies will be necessary to elucidate the specific prognostic outcomes of injuries due to falls among parkinsonian patients, and the impact of these injuries on disease progression and quality of life. © 2004 Movement Disorder Society
Methadone for refractory restless legs syndrome
Authors: Ondo William G. 
Published: December 2004

AbstractMost cases of restless legs syndrome (RLS) initially respond well to dopaminergic agonists. However, an unknown percentage of patients is intolerant of dopaminergic adverse events, initially or subsequently refractory, or develops limiting augmentation. We administered methadone 5 to 40 mg/day (final dose, 15.6 ± 7.7) to 29 RLS patients who failed dopaminergics. They were currently taking or had previously tried 5.9 ± 1.7 (range, 3–9) different medications for RLS and 2.9 ± 0.8 (range, 2–4) different dopaminergics. Of the 27 patients who met inclusion criteria, 17 have remained on methadone for 23 ± 12 months (range, 4–44 months) at a dose of 15.5 ± 7.7 mg/day; 2 dialysis RLS patients died while on methadone, and 8 stopped the treatment (5 for adverse events, 2 for lack of efficacy, and 1 for logistical reasons). All patients who remain on methadone report at least a 75% reduction in symptoms, and none have developed augmentation. Methadone should be considered in RLS patients with an unsatisfactory dopaminergic response. © 2004 Movement Disorder Society
Challenging conventional wisdom: The etiologic role of dopamine oxidative stress in Parkinson's disease
Authors: Ahlskog J. Eric 
Published: December 2004

AbstractOxidative stress is well documented in Parkinson's disease (PD) and has been attributed to dopamine oxidative metabolism. However, evidence of oxidative stress is found in a variety of neurodegenerative disorders, suggesting that more general factors are responsible or that cytodestructive processes secondarily generate oxyradical products. Increasing evidence points away from dopamine metabolism as an important contributor to PD neurodegeneration. Predictions from the dopamine oxidative stress hypothesis of PD reveal multiple inconsistencies. Although the clinical and therapeutic importance of the nigrostriatal dopaminergic system is undeniable, PD neuropathology is much more widespread. © 2004 Movement Disorder Society
Functional impairment as a risk factor for urinary incontinence among older Americans
Authors: Jenkins Kristi Rahrig , Fultz Nancy H. 
Published: December 2004

AbstractAimsUsing a large nationally representative sample of older Americans we investigate four domains of functional impairment as possible risk factors for the subsequent development of urinary incontinence (UI) symptoms.MethodsData from three waves (1993, 1995, 1998) of the Asset and Health Dynamics among the Oldest Old (AHEAD) survey were used to model the effects of functional impairment on the onset of UI symptoms.ResultsA greater number of serious chronic conditions and functional impairment in the lower body mobility domain increased the odds of the onset of mild UI (vs. remaining continent). Factors that contributed to greater odds of the onset of severe UI (vs. remaining continent) were older age, being represented by a proxy respondent, and functional impairment in the strength domain.ConclusionsUnderstanding the possible relationship between functional impairment and UI is an important step toward developing appropriate interventions for the prevention, treatment, or management of urine loss. © 2004 Wiley‐Liss, Inc.
Synthesis and photoinduced transformation of helical aromatic polyamides containing atropisomeric biphenylene units and azobenzene segments in the main chain
Authors: Agata Yuya , Kobayashi Motoyasu , Kimura Hiroshi , Takeishi Makoto 
Published: December 2004

AbstractOptically active helical polyamides were synthesized by condensation of axially dissymmetric (R)‐ or (S)‐6,6′‐diamino‐2,2′‐dimethylbiphenyl with aromatic dicarbonyl chlorides. The wholly aromatic polyamides obtained were soluble in various low‐polarity organic solvents such as tetrahydrofuran and chloroform, as well as in polar N,N‐dimethylacetamide. Excellent thermal stability of the helical structure was observed for the polyamide obtained with 4,4′‐dicarbonylbiphenyl chloride in refluxing N,N‐dimethylacetamide. Chiroptical data obtained from the circular dichroism spectra showed that the helical conformation of the polyamide containing azobenzene segments in the main chain can be transformed reversibly on irradiation with UV–visible light because of the trans–cis isomerization of the segments. Copyright © 2004 Society of Chemical Industry
NMR imaging of the diffusion of water at 310 K into poly[(2‐hydroxyethyl methacrylate)‐co‐(tetrahydrofurfuryl methacrylate)] containing vitamin B12 or aspirin
Authors: Chowdhury Mohammad A , Hill David JT , Whittaker Andrew K 
Published: December 2004

AbstractThe ingress of water into copolymers of 2‐hydroxyethyl methacrylate (HEMA) and tetrahydrofurfuryl methacrylate (THFMA) loaded with either one of two model drugs, ie vitamin B12 or aspirin, was studied at 310 K using three‐dimensional nuclear magnetic resonance (3D NMR) imaging. The poly(HEMA) was loaded with 5 wt% of the drugs. From the imaging profiles it was observed that incorporation of vitamin B12 into the polymers rich in HEMA resulted in crack formation at the interface between the rubbery region and the glassy core on sorption of water, although these cracks were ‘healed’ behind the diffusion front. However, for the copolymers with low HEMA contents and for those containing aspirin, no evidence for similar crack formation was found. For the copolymers loaded with 5 wt% of aspirin or vitamin B12 the values of the water diffusion coefficients, determined by curve‐fitting the relative water concentration profiles from magnetic resonance imaging (MRI) measurements, were found to be smaller than those obtained from a mass uptake study. Copyright © 2004 Society of Chemical Industry
Complex formation of montmorillonite clay with polymers. Part 2: The use of montmorillonite clay–vinyl monomer complex as a comonomer in the copolymerization reaction of styrene–acrylonitrile monomers
Authors: Khalil Hanaa , Mahajan Devinder , Rafailovich Mariam 
Published: December 2004

AbstractThe bulk copolymerization of styrene–acrylonitrile monomers using styrene‐N+–montmorillonite complex as a comonomer in the polymerization was studied. The X‐ray diffraction (XRD) analysis showed that part of the styrene‐N+–montmorillonite complex remained non‐dispersed (immiscible) and the copolymer was excluded from the interlayer of the immiscible part of the clay. The successive chemical extraction process revealed that a reasonable amount of the styrene–acrylonitrile copolymer was directly attached to the styrene‐N+–montmorillonite complex and enveloped the clay. Highly exfoliated clay lamella and nanospheres (3–5 nm) were observed by transmission electron microscopy (TEM). The montmorillonite clay assume two different morphologies, immiscible and exfoliated, on the basis of the XRD and TEM data. A simple method of calculation of the ratio of the exfoliated/immiscible amounts of the clay indicated that the amount of the styrene‐N+–montmorillonite complex exfoliated into separate lamella was 40 % (w/w) of the amount of the clay samples containing 2 % of the (styrene‐N+–montmorillonite complex) clay. This amount of exfoliated clay decreases with the increase of the concentration of the clay. The presence of the styrene‐N+–montmorillonite clay in the copolymerization reaction had a minor effect on both the copolymer composition and the molecular weight. Modification of the clay with the derivatized styrene monomer can achieve a nanocomposite using a percentage no more than 4 % (w/w) of complex in the copolymer. Copyright © 2004 Society of Chemical Industry