bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitration of Heteroaryltrimethyltins by Tetranitromethane and Dinitrogen Tetroxide: Mechanistic Aspects, Scope and Limitations
Authors: Fargeas Valérie , Favresse Fabien , Mathieu Didier , Beaudet Isabelle , Charrue Pierre , Lebret Bruno , Piteau Marc , Quintard Jean‐Paul 
Published: April 2003

AbstractThe nitration of 2‐(trimethylstannyl)heteroarenes by tetranitromethane (TNM) or dinitrogen tetroxide has been shown to be possible when the HOMO energy of the heteroaryltin is high enough to allow the formation of the corresponding radical cation. The reaction proceeds through a charge‐transfer complex between heteroaryltin and TNM, followed by a single‐electron transfer, which is enhanced under sunlamp irradiation. Accordingly, 2‐nitrobenzo[b]furan, 2‐nitrobenzo[b]thiophene, 2‐nitropyridine and 2‐nitroindoles were obtained by this method. However, the nitration of 2‐stannylated pyrimidine or of stannylated 1,3,5‐triazines has been shown to be impossible, due to the low energy of their HOMO orbitals. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
A flexible nudged elastic band program for optimization of minimum energy pathways using ab initio electronic structure methods
Authors: Alfonso Dominic R. , Jordan Kenneth D. 
Published: April 2003

AbstractA driver program for carrying out nudged elastic band optimizations of minimum energy reaction pathways is described. This approach allows for the determination of minimum energy pathways using only energies and gradient information. The driver code has been interfaced with the GAUSSIAN 98 program. Applications to two isomerization reactions and to a cluster model for H2 desorption from the Si(100)‐2x1 surface are presented. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 990–996, 2003
Pharmaceutical antibiotic compounds in soils – a review
Authors: Thiele‐Bruhn Sören 
Published: April 2003

AbstractAntibiotics are highly effective, bioactive substances. As a result of their consumption, excretion, and persistence, they are disseminated mostly via excrements and enter the soils and other environmental compartments. Resulting residual concentrations in soils range from a few μg upto g kg–1 and correspond to those found for pesticides. Numerous antibiotic molecules comprise of a non‐polar core combined with polar functional moieties. Many antibiotics are amphiphilic or amphoteric and ionize. However, physicochemical properties vary widely among compounds from the various structural classes. Existing analytical methods for environmental samples often combine an extraction with acidic buffered solvents and the use of LC‐MS for determination. In soils, adsorption of antibiotics to the organic and mineral exchange sites is mostly due to charge transfer and ion interactions and not to hydrophobic partitioning. Sorption is strongly influenced by the pH of the medium and governs the mobility and transport of the antibiotics. In particular for the strongly adsorbed antibiotics, fast leaching through soils by macropore or preferential transport facilitated by dissolved soil colloids seems to be the major transport process. Antibiotics of numerous classes are photodegraded. However, on soil surfaces this process if of minor influence. Compared to this, biotransformation yields a more effective degradation and inactivation of antibiotics. However, some metabolites still comprise of an antibiotic potency. Degradation of antibiotics is hampered by fixation to the soil matrix; persisting antibiotics were already determined in soils. Effects on soil organisms are very diverse, although all antibiotics are highly bioactive. The absence of effects might in parts be due to a lack of suitable test methods. However, dose and persistence time related effects especially on soil microorganisms are often observed that might cause shifts of the microbial community. Significant effects on soil fauna were only determined for anthelmintics. Due to the antibiotic effect, resistance in soil microorganisms can be provoked by antibiotics. Additionally, the administration of antibiotics mostly causes the formation of resistant microorganisms within the treated body. Hence, resistant microorganisms reach directly the soils with contaminated excrements. When pathogens are resistant or acquire resistance from commensal microorganisms via gene transfer, humans and animals are endangered to suffer from infections that cannot be treated with pharmacotherapy. The uptake into plants even of mobile antibiotics is small. However, effects on plant growth were determined for some species and antibiotics.
Influence of load on shrinkage behavior of peat soils
Authors: Oleszczuk Ryszard , Bohne Klaus , Szatylowicz Jan , Brandyk Tomasz , Gnatowski Tomasz 
Published: April 2003

AbstractThe shrinkage of the peat soils that accompanies the soil moisture changes is an important feature of such soils and has strong influence on their physical attributes and soil water management. The relationships between soil moisture and volume are often described using shrinkage characteristic curves by relating void ratio (volume of voids per unit volume of solids) to moisture ratio (volume of water per volume of solids). For conversion of soil volume changes into cracks volume and subsidence, a dimensionless shrinkage geometry factor is used. The paper presents results of volumetric shrinkage behavior and the geometry factor at various loads in sedge and alder peat soils. The measurements were conducted on undisturbed soil samples without applying a load and with loads corresponding to field overburden. The shape of the shrinkage characteristics of such soils were completely different from those of clay soils. The application of loads did not significantly influence the shrinkage characteristics curve. The applied load strongly influenced on relationship between shrinkage geometry factor and the moisture ratio, showing higher values of subsidence and lower values of crack volume in comparison with unloaded conditions.
Nanocomposites from Layered Silicates: Graft Polymerization with Intercalated Ammonium Peroxides
Authors: Albrecht Martin , Ehrler Stefan , Mühlebach Andreas 
Published: April 2003

AbstractNanocomposites were prepared by butyl acrylate graft polymerization from montmorillonite‐type layered silicates. Successful polymer grafting required novel dialkyl peroxides comprising two cationic ammonium groups, which were intercalated in the layered silicate by cation exchange. Thermal cleavage of the peroxide functionality in the presence of butyl acrylate as monomer initiated polymerization and hence exfoliation of the layers. Detailed examination of this process shows that the polymerization cannot be controlled by external nitroxides.
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Alteration of O6‐methylguanine‐DNA methyltransferase in colorectal neoplasms in sporadic and familial adenomatous polyposis patients
Authors: Kim Sun Hee , Bae Soo In , Lee Hye Seung , Kim Woo Ho 
Published: April 2003

AbstractDNA repair failure is known to be a critical event during carcinogenesis of colorectal cancers. To investigate whether O6‐methylguanine‐DNA methyltransferase (MGMT) is altered during colorectal carcinogenesis, we performed immunohistochemical staining on 265 sporadic colorectal cancers, 113 sporadic adenomas, 33 familial adenomatous polyposis (FAP) colorectal cancers, and 93 FAP adenomas. Sixty‐seven of 265 sporadic colorectal cancer cases and five of 113 sporadic adenoma cases showed loss of MGMT expression (P < 0.001). Among FAP patients, four of 33 cancers and six of 93 adenomas showed loss of MGMT protein expression. When we compared the association between MGMT promoter hypermethylation and protein expression, almost all cases without a methylated allele were positive for the expression of MGMT. In contrast, cases with promoter methylation frequently showed loss of MGMT expression (P < 0.01). Loss of MGMT was correlated with some clinicopathological characteristics, i.e., tumor invasion (P = 0.013) and stage (P = 0.035) in sporadic colorectal cancer, and degree of atypism (P = 0.042) in sporadic adenoma. Our results show that loss of expression of MGMT occurs more frequently in cancer than in adenoma in both sporadic and FAP patients, and that loss of expression of MGMT is associated with hypermethylation of the promoter area of MGMT gene. © 2003 Wiley‐Liss, Inc.
Reaction Propagation Rates in HMX at High Pressure
Authors: Esposito Anthony P. , Farber Daniel L. , Reaugh John E. , Zaug Joseph M. 
Published: April 2003

AbstractWe have measured the reaction propagation rate (RPR), or deflagration rate, in octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) powder in a diamond anvil cell over the pressure range 0.7–35 GPa. Numerical simulations of the RPR of pressurized HMX were also performed for comparison to the experimental results obtained. The simulated RPR values closely approximate the observed rates at pressures up to 3 GPa, and serve as a bridge to lower‐pressure deflagration rates for HMX in the literature. However, at higher pressures the simulated RPR values deviate significantly from our experimental results. This suggests that further refinement to the computational model is required for the calculated RPR values to approach those observed at higher pressures.
QSAR and Mechanism of Action For Aquatic Toxicity of Cationic Surfactants
Authors: Roberts David W. , Costello Jayne 
Published: April 2003

AbstractThis paper considers the mechanism of aquatic toxicity of cationic organic compounds and the relationship of toxicity with log P (P=octanol/water partition coefficient). The rather complex log P calculation method given by Leo and Hansch for cationics is reconsidered and the underlying solvation chemistry is reinterpreted. This reinterpretation is tested by application to micellisation data for cationic surfactants. It is found that in its micellisation potential, expressed as pCMC, a cationic surfactant is similar to the anionic surfactant with the same hydrophobe. Our modifications, derived from this finding, to the log P calculation for cationics, lead to a cationics fish toxicity QSAR whose slope and intercept are close to the range commonly found for polar narcosis QSARs. The compounds included in this QSAR include 2 non‐surfactants, indicating that for cationics, as already observed for anionics and nonionics, whether a compound is a surfactant or not is irrelevant to its toxicity. That the cationics act by a polar narcosis mechanism is supported by the results of mixture toxicity studies, indicating additive joint action for mixtures of a cationic with known polar narcotics and independent joint action for a mixture of a cationic with a known general narcotic.
Advances in Quantitative Ion Character‐Activity Relationships (QICARs): Using Metal‐Ligand Binding Characteristics to Predict Metal Toxicity
Authors: Ownby David R. , Newman Michael C. 
Published: April 2003

AbstractEnvironmental toxicologists readily adopted QSARs from pharmacology to predict organic contaminant toxicity. In contrast, models relating metal ion characteristics to their bioactivity remain poorly explored and underutilized. Quantitative Ion Character‐Activity Relationships (QICARs) have recently been developed to predict metal toxicity. The QICAR approach, based on metal‐ligand binding tendencies, has been applied successfully to a wide range of effects, species, and media on a single metal basis. In previous single metal studies, a softness parameter and the |log KOH| were among the ion qualities with the highest predictive value for toxicity.
Product ion scanning using a Q‐q‐Qlinear ion trap (Q TRAPTM) mass spectrometer
Authors: Hager James W. , Yves Le Blanc J. C. 
Published: April 2003

AbstractThe use of a Q‐q‐Qlinear ion trap instrument to obtain product ion spectra is described. The instrument is based on the ion path of a triple quadrupole mass spectrometer with Q3 operable as either a conventional RF/DC quadrupole mass filter or a linear ion trap mass spectrometer with axial ion ejection. This unique ion optical arrangement allows de‐coupling of precursor ion isolation and fragmentation from the ion trap itself. The result is a high sensitivity tandem mass spectrometer with triple quadrupole fragmentation patterns and no inherent low mass cut‐off. The use of the entrance RF‐only section of the instrument as accumulation ion trap while the linear ion trap mass spectrometer is scanning enhances duty cycles and results in increased sensitivities by as much as a factor of 20. The instrument is also capable of all of the triple quadrupole scans including multiple‐reaction monitoring (MRM) as well as precursor and constant neutral loss scanning. The high product ion scanning sensitivity allows the recording of useful product ion spectra near the MRM limit of quantitation. Copyright © 2003 John Wiley & Sons, Ltd.
The mystery of striated cloud heads in satellite imagery
Authors: Dixon R. S. , Browning K. A. , Shutts G. J. 
Published: April 2003

AbstractStriated cloud heads are associated with some of the most extreme cases of rapid cyclogenesis. Animations of two clear examples are presented and one is interpreted in detail in the light of a Limited Area Model analysis. Six alternative dynamical explanations are considered but none satisfactorily fits all the evidence. Copyright © 2000 Royal Meteorological Society.
Intracellular localization of the 90 kDA heat shock protein (HSP90α) determined by expression of a EGFP—HSP90α‐fusion protein in unstressed and heat stressed 3T3 cells
Authors: Langer Thomas , Rosmus Susann , Fasold Hugo 
Published: April 2003

AbstractHeat shock protein 90 (Hsp90) is an abundant protein and essential for all eukaryotic cells. The expression of Hsp90 is further enhanced after exposure to stress factors, e.g. a heat shock. Many proteins interacting with Hsp90 as well as the various functions for Hsp90 have been described. In this study, an Hsp90α fusion protein along with the enhanced green fluorescence protein (EGFP) was expressed under the control of the human cytomegalovirus immediate early promoter. EGFP—Hsp90α was mainly localized in the cytoplasm, with only minor amounts inside the nuclei. No EGFP—Hsp90α could be detected inside the nucleoli. Following exposure to elevated temperatures, higher amounts of EGFP—Hsp90α are inside the nucleus, but not within the nucleoli. As the most remarkable finding under these conditions, an association of EGFP—Hsp90α with the nuclear membrane became visible.
Does cognitive-behavioural therapy influence the long-term outcome of generalized anxiety disorder? An 8–14 year follow-up of two clinical trials
Authors: DURHAM R. C. , CHAMBERS J. A. , MACDONALD R. R. , POWER K. G. , MAJOR K. 
Published: April 2003

Background. Generalized anxiety disorder is a common condition of excessive worry and tension which tends to run a chronic course associated with significant psychiatric and medical problems. Cognitive behaviour therapy (CBT) has been shown to be of clinical value in about 50% of cases with treatment gains maintained over follow-up periods ranging from 6 to 12 months. The potential value of CBT over the longer term has not been subject to rigorous investigation.Method. Results are reported of 8–14 year follow-up of two randomized controlled trials of cognitive-behaviour therapy for generalized anxiety disorder employing structured interview with an assessor blind to initial treatment condition. Comparison groups included medication and placebo in one study based in primary care, and analytical psychotherapy in the other based in secondary care. Follow-up samples (30% and 55% of trial entrants) were broadly representative of the original cohorts.Results. Overall, 50% of participants were markedly improved of whom 30–40% were recovered (i.e. free of symptoms). Outcome was significantly worse for the study based in secondary care in which the clinical presentation of participants was more complex and severe. For a minority (30–40%), mainly from the secondary care study, outcome was poor. Treatment with CBT was associated with significantly lower overall severity of symptomatology and less interim treatment, in comparison with non-CBT conditions, but there was no evidence that CBT influenced diagnostic status, probability of recovery or patient perceptions of overall improvement.Conclusions. Both CBT and the complexity and severity of presenting problems appear to influence the long-term outcome of GAD.
A demonstration of attentional bias, using a novel dual task paradigm, towards clinically salient material in recovering alcohol abuse patients?
Authors: WATERS HELEN , GREEN MICHAEL W. 
Published: April 2003

Background. This study examined whether alcohol abuse patients are characterized either by enhanced schematic processing of alcohol related cues or by an attentional bias towards the processing of alcohol cues.Method. Abstinent alcohol abusers (N=25) and non-clinical control participants (N=24) performed a dual task paradigm in which they had to make an odd/even decision to a centrally presented number while performing a peripherally presented lexical decision task. Stimuli on the lexical decision task comprised alcohol words, neutral words and non-words. In addition, participants completed an incidental recall task for the words presented in the lexical decision task.Results. It was found that, in the presence of alcohol related words, the performance of patients on the odd/even decision task was poorer than in the presence of other stimului. In addition, patients displayed slower lexical decision times for alcohol related words. Both groups displayed better recall for alcohol words than for other stimuli.Conclusions. These results are interpreted as supporting neither model of drug cravings. Rather, it is proposed that, in the presence of alcohol stimuli, alcohol abuse patients display a breakdown in the ability to focus attention.
Does ‘errorless learning’ compensate for neurocognitive impairments in the work rehabilitation of persons with schizophrenia?
Authors: KERN R. S. , GREEN M. F. , MINTZ J. , LIBERMAN R. P. 
Published: April 2003

Background. Because neurocognitive impairments of schizophrenia appear to be ‘rate limiting’ in the acquisition of skills for community functioning, it is important to develop efficacious rehabilitative interventions that can compensate for these impairments. Procedures based on errorless learning may facilitate work rehabilitation because they effectively automate training of work and other skills, thereby reducing the cognitive burden on persons with schizophrenia.Method. The present study examined the ability of a training method based on errorless learning to compensate for neurocognitive deficits in teaching two entry-level job tasks (index card filing and toilet-tank assembly) to a sample of 54 unemployed, clinically stable schizophrenic and schizoaffective disorder out-patients. Participants were randomly assigned to one of two training groups, errorless learning v. conventional trial-and-error type instruction. Prior to randomization, all subjects were administered a neurocognitive battery. Job task performance was assessed by percentage accuracy scores immediately after training.Results. For three of the six inter-relationships among neurocognitive functioning and training condition, the pattern was the same: the errorless learning group scored high in job task performance regardless of neurocognitive impairment, whereas the conventional instruction group showed a close correspondence between job task performance and degree of neurocognitive impairment.Conclusions. These findings support errorless learning as a technique that can compensate for neurocognitive deficits as they relate to the acquisition of new skills and abilities in the work rehabilitation of persons with schizophrenia.
Effect of neuroticism, response style and information processing on depression severity in a clinically depressed sample
Authors: LAM D. , SMITH N. , CHECKLEY S. , RIJSDIJK F. , SHAM P. 
Published: April 2003

Background. It is postulated that individuals who score high on neuroticism would ruminate when faced with stress. A ruminative response style to depression is associated with faulty attribution and higher dysfunctional beliefs, which in turn is associated with a higher level of depression and hopelessness. Distraction is associated with less severe depression. Evidence supporting these hypotheses mainly comes from a non-clinical population. Hence it is not clear if these theories apply to clinical depression.Method. One hundred and nine out-patients suffering from unipolar major depressive disorder were recruited to test these theories, using model-fitting analysis technique.Results. Certain rumination responses to depression were associated with higher levels of depression and hopelessness, faulty attribution and dysfunctional attitudes when gender and the level of depression were controlled. Principal component analysis of the Rumination Scale yielded four factors: ‘symptom-based rumination’, ‘isolation/introspection’, ‘self-blame’ and ‘analyse to understand’. Unlike the other factors, ‘analyse to understand’ did not correlate with the level of depression. Model fitting analysis, though not reflecting entirely the true model, captures most of the hypothesized relationships between important variables. Neuroticism was associated with stress. Rumination was associated with an increased level of dysfunctional beliefs and faulty attribution, which in turn was associated with increased severity of depression. Distraction, in contrast, was associated with lower levels of negative mood.Conclusion. The results of our study support the importance of teaching depressed patients to manage their depressive symptoms by avoiding rumination about their symptoms and engaging in distracting and pleasurable activities.
Changing management in Scottish birch woodlands: a potential threat to local invertebrate biodiversity
Authors: Woodcock B.A. , Leather S.R. , Watt A.D. 
Published: April 2003

AbstractThe silvicultural management of Scottish birch woodlands for timber production is replacing traditional low intensity management practices, such as domesticated livestock grazing. These new management practices involve thinning of existing woodlands to prescribed densities to maximize biomass and timber quality. Although presently infrequent, the wide scale adoption of this practice could affect invertebrate community diversity. The impact of these changes in management on Staphylinidae and Carabidae (Coleoptera) in 19 woodlands in Aberdeenshire, north-east Scotland was investigated. Grazing and logging practices were important determinants of beetle community structure. Woodland area had no effect on any measure of beetle community structure, although isolation did influence the abundance of one carabid species. Changes towards timber production forestry will influence the structure of invertebrate communities, although the scale at which this occurs will determine its effect.
Toll-like receptor ligand links innate and adaptive immune responses by the production of heat-shock proteins
Authors: Kumaraguru Udayasankar , Pack Christopher D , Rouse Barry T 
Published: April 2003

Abstract
The report shows that CpG can exert additional adjuvant effects by inducing cells that are normally inferior antigen (Ag)-presenting cells to participate in immune induction by cross-priming. Macrophages (Mφ) exposed to protein Ag in the presence of bioactive CpG DNA released material that induced primary CD8+ T cell responses in DC-naïve T cell cultures. This cross-priming event was accompanied by up-regulation of the stress protein response as well as inflammatory cytokine expression in treated Mφ. The material released was indicated to contain inducible heat shock protein-70 and epitope peptide, which in turn, were presented by dendritic cells (DCs) to responder T cells. Such an adjuvant effect by CpG may serve to salvage immunogenic material from otherwise inert depot cellular sites and additionally stimulate DCs to effectively cross-prime. The cross-priming, shown also to occur in vivo, may be particularly useful when Ag doses are low and have minimal opportunity for delivery to DCs for consequent direct priming.