bluuebunny/crossref_metadata_2025 huggingface dataset:
Specific interactions and phase behavior of ternary poly(2‐vinylpyridine)/poly(N‐vinyl‐2‐pyrrolidone)/bisphenol A blends
Authors: Li Xue‐Dong , Goh S. H.
Published: August 2002

Hydrogen‐bonding interactions between bisphenol A (BPA) and two proton‐accepting polymers, poly(2‐vinylpyridine) (P2VPy) and poly(N‐vinyl‐2‐pyrrolidone) (PVP), were examined by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The Flory–Huggins interaction‐energy densities of BPA/P2VPy and BPA/PVP blends were determined by the melting point depression method. The interaction parameters for both BPA/P2VPy and BPA/PVP blend systems were negative, demonstrating the miscibility of BPA with P2VPy as well as PVP. The miscibility of ternary BPA/P2VPy/PVP blends was examined by DSC, optical observation, and solid‐state nuclear magnetic resonance spectroscopy. The experimental phase behavior of the ternary blend system agreed with the spinodal phase‐separation boundary calculated using the determined interaction‐energy densities. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1125–1134, 2002
Diffusion mobility of reactants, phase equilibrium, and specific features of radical copolymerization kinetics in the nonyl acrylate/2‐methyl‐5‐vinyltetrazole system
Authors: Mikhailov Yu. M. , Ganina L. V. , Kurmaz S. V. , Smirnov V. S. , Roshchupkin V. P.
Published: August 2002

Combined analysis of experimental data on monomer diffusion, phase equilibrium, and copolymerization kinetics in systems of monomers (nonyl acrylate and 2‐methyl‐5‐vinyltetrazole) as well as their copolymers and homopolymers was carried out. The composition of the mixture in the vicinity of the growing macroradical can differ significantly from the average composition in the whole reactor volume because of consumption of the more‐reactive reactant 2‐methyl‐5‐vinyltetrazole. Nonyl acrylate exhibited limited compatibility with copolymers enriched in 2‐methyl‐5‐vinyltetrazole and its homopolymer. Phase diagrams were obtained for the latter homopolymer. The concentration plots of the diffusion coefficients of both monomers in their copolymers of various compositions were determined. Microphase separation was observed at specific conversions in the reaction system where the composition of a copolymer and its concentration in a monomer solution approached the binodal of the phase diagram. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1383–1389, 2002
Hydrophobicity of fluoro‐containing physical crosslinkage domains in hydrophobically modified poly(acrylic acid) gels
Authors: Tian Qin , Zhao Xian , Tang Xiaozhen , Zhang Yunxiang
Published: August 2002

A series of hydrophobically modified poly(acrylic acid) gels were prepared by the radical copolymerization of acrylic acid and small amounts of hydrophobic comonomers, 2‐(N‐ethylperfluorooctane‐sulfoamido)ethyl methacrylate and lauryl acrylate, in tert‐butanol. The effects of the fractions and species of hydrophobes on hydrophobic association were determined. The hydrophobic association within the hydrophobically modified gels was proven with measurements of swelling and fluorescence as well as Fourier transform infrared spectroscopy. Fluorocarbon‐modified hydrogels showed stronger hydrophobicity than hydrocarbon‐modified hydrogels. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1236–1244, 2002
Thermal shrinkage stress in high‐speed‐spun, high molecular weight poly(ethylene terephthalate) filaments
Authors: Lim Jung Yul , Kim Sang Yong
Published: August 2002

High‐speed spinning of poly(ethylene terephthalate) with an intrinsic viscosity of 0.98 dL/g was performed at a take‐up velocity of 2.5–5.5 km/min, and the effects of the fiber structure on the isothermal and nonisothermal shrinkage‐stress evolution in as‐spun filaments were investigated. In isothermal measurements, the peak shrinkage stress was consistent with the degree of amorphous orientation, whereas the so‐called frozen stress relaxation was rather constant with respect to the take‐up velocity. The maximum shrinkage stress in nonisothermal testing was also consistent with an amorphous orientation. A spontaneous elongation phenomenon took place for filaments spun at 2.5 and 3 km/min that resulted in the lowering of shrinkage stresses in both experiments. A simple calculation showed that the inertial force in the spin line was about half of the resultant shrinkage force. Filaments spun at 5.5 km/min had markedly lower shrinkage stresses and shrinkage with respect to the degree of amorphous orientation. This was attributed to the fiber structure, which gave a much lower loss‐tangent maximum for these filaments. In addition, a hypothetical model is proposed suggesting the possibility that filaments spun at 5.5 km/min may have narrow tie‐chain‐length distributions that provide relatively longer shortest tie molecules. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 964–972, 2001
Surgical experience in patients with cystic fibrosis: A 25‐year perspective
Authors: Saltzman Daniel A. , Johnson Eric M. , Feltis Brad A. , Wilienski Catherine , Warwick Warren J. , Leonard Arnold S.
Published: August 2002

The spectrum of surgical diseases in patients with cystic fibrosis (CF) has not been comprehensively studied. A retrospective review of 792 consecutive patients with CF presenting over a 25 year period (1970–1994) was made to determine the incidence of operations, procedures performed, complications encountered, and impact on physical development and pumonary function tests (PFTs).

A total of 191 operations were performed on 130 (16%) of the 792 patients; 98 operations (51%) were abdominal, 58 (30%) thoracic, and 31 (16%) hernias; 64 were male, and 66 female; average age was 14 ± 10 years. Complications occurred in 12 (16%); 9 deaths were from progressive respiratory failure, 2 from superficial wound infections, and 1 from an episode of line sepsis. In the first 15 years, 9 complications occurred in 126 operations vs. 3 in 73 operations during the last 10 years. Operations were classified as emergent, urgent, or elective. Of the 9 deaths, 8 occurred after emergent or urgent operations (4 abdominal and 4 thoracic), while 1 death occured following elective herniorrhaphy. For each subgroup, (abdominal, thoracic, and hernia), there was no difference in height/weight indicies, peak flow, forced vital capacity (FVC), forced expired volume in 1 sec (FEV1), or FEV1/FVC ratio when comparing 1 year preoperation and 1 year postoperation.

In conclusion, patients in this high‐risk population were operated on with few complications, but when a complication occured it tended to be pulmonary and fatal (4.7% of all operations). Furthermore, operations did not cause significant deteriorations in PFTs and they did not cause these children to fall off their expected age‐adjusted growth curves. Pediatr Pulmonol. 2002; 33:106–110. © 2002 Wiley‐Liss, Inc.
Transition programs in cystic fibrosis centers: Perceptions of patients
Authors: Anderson Deborah L. , Flume Patrick A. , Hardy Kristina K. , Gray Sue
Published: August 2002

There is a growing population of adults with cystic fibrosis (CF) and a need for development of adult CF programs. Recommendations for transfer of patients from pediatric care to an adult program include a transition program. The purpose of this study was to survey adult CF patients to assess their own concerns regarding this issue.

A survey was sent to all 1,288 members of the International Association of Cystic Fibrosis Adults (IACFA), with a response rate of 25.9% (n = 334). The majority of patients (81.2%) received care from a CF center; the major difference between those seen at a CF center and those seen at another facility was proximity to a CF center. Nearly one‐fourth of patients seen at a CF center continued to receive care from a pediatrician even though a CF‐trained internist was available; though these patients were younger, their mean age was still about 30 years. Patients seen by a pediatrician were more like to be students and to live with their parents. Those patients seen in an adult program described a variety of criteria for their transfer to the adult pro‐gram, but there were no consistent findings to suggest a standard transition program. Indeed, many patients did not meet the adult team until the time of the transfer. Most importantly, the patients reported their level of concern about transfer as minimal, far less than what CF physicians had perceived.

These differences may impede the successful transition of patients into an adult program. Pediatr Pulmonol. 2002; 33:327–331. © 2002 Wiley‐Liss, Inc.
Alignments grow, secondary structure prediction improves
Authors: Przybylski Dariusz , Rost Burkhard
Published: August 2002

Using information from sequence alignments significantly improves protein secondary structure prediction. Typically, more divergent profiles yield better predictions. Recently, various groups have shown that accuracy can be improved significantly by using PSI‐BLAST profiles to develop new prediction methods. Here, we focused on the influences of various alignment strategies on two 8‐year‐old PHD methods. The following results stood out. (i) PHD using pairwise alignments predicts about 72% of all residues correctly in one of the three states: helix, strand, and other. Using larger databases and PSI‐BLAST raised accuracy to 75%. (ii) More than 60% of the improvement originated from the growth of current sequence databases; about 20% resulted from detailed changes in the alignment procedure (substitution matrix, thresholds, and gap penalties). Another 20% of the improvement resulted from carefully using iterated PSI‐BLAST searches. (iii) It is of interest that we failed to improve prediction accuracy further when attempting to refine the alignment by dynamic programming (MaxHom and ClustalW). (iv) Improvement through family growth appears to saturate at some point. However, most families have not reached this saturation. Hence, we anticipate that prediction accuracy will continue to rise with database growth. Proteins 2002;46:197–205. © 2001 Wiley‐Liss, Inc.
3′,5′‐Cyclic nucleotide phosphodiesterases class III: Members, structure, and catalytic mechanism
Authors: Richter Wito
Published: August 2002

3′,5′‐Cyclic nucleotide phosphodiesterases (PDEs) comprise a superfamily of enzymes that were previously divided by their primary structure into two major classes: PDE class I and II. The 3′,5′‐cyclic AMP phosphodiesterase from Escherichia coli encoded by the cpdA gene does not show any homology to either PDE class I or class II enzymes and, therefore, represents a new, third class of PDEs. Previously, information about essential structural elements, substrate and cofactor binding sites, and the mechanism of catalysis was unknown for this enzyme. The present study shows by computational analysis that the enzyme encoded by the E. coli cpdA gene belongs to a family of phosphodiesterases that closely resembles the catalytic machinery known from purple acid phosphatases and several other dimetallophosphoesterases. They share both the conserved sequence motif, D‐(X)n‐GD‐(X)n‐GNH[E/D]‐(X)n‐H‐(X)n‐GHXH, which contains the invariant residues forming the active site of purple acid phosphatases, a binuclear Fe3+‐Me2+‐containing center, as well as a βαβαβ motif as a typical secondary structure signature. Furthermore, the known biochemical properties of the bacterial phosphodiesterase encoded by the cpdA gene, such as the requirement of iron ions and a reductant for maintaining its catalytic activity, support this hypothesis developed by computational analysis. In addition, the availability of atomic coordinates for several purple acid phosphatases and related proteins allowed the generation of a three‐dimensional model for class III cyclic nucleotide phosphodiesterases. Proteins 2002;46:278–286. © 2002 Wiley‐Liss, Inc.
Enzymatic circularization of a malto‐octaose linear chain studied by stochastic reaction path calculations on cyclodextrin glycosyltransferase
Authors: Uitdehaag Joost C.M. , van der Veen Bart A. , Dijkhuizen Lubbert , Elber Ron , Dijkstra Bauke W.
Published: August 2002

Cyclodextrin glycosyltransferase (CGTase) is an enzyme belonging to the α‐amylase family that forms cyclodextrins (circularly linked oligosaccharides) from starch. X‐ray work has indicated that this cyclization reaction of CGTase involves a 23‐Å movement of the nonreducing end of a linear malto‐oligosaccharide from a remote binding position into the enzyme acceptor site. We have studied the dynamics of this sugar chain circularization through reaction path calculations. We used the new method of the stochastic path, which is based on path integral theory, to compute an approximate molecular dynamics trajectory of the large (75‐kDa) CGTase from Bacillus circulans strain 251 on a millisecond time scale. The result was checked for consistency with site‐directed mutagenesis data. The combined data show how aromatic residues and a hydrophobic cavity at the surface of CGTase actively catalyze the sugar chain movement. Therefore, by using approximate trajectories, reaction path calculations can give a unique insight into the dynamics of complex enzyme reactions. Proteins 2001;43:327–335. © 2001 Wiley‐Liss, Inc.
Finite dose diffusion studies: III. Effects of temperature, humidity and deposit manipulation on NAA penetration through isolated tomato fruit cuticles
Authors: Knoche Moritz , Bukovac Martin J
Published: August 2002

Effects of temperature, humidity, rewetting and removal of deposits on penetration of NAA [2‐(1‐naphthyl)acetic acid] through isolated tomato (Lycopersicon esculentum Mill) fruit cuticles were studied using a finite dose diffusion system. In this system, an aqueous 5‐µl droplet (0.1 mM NAA in 20 mM citric acid buffer) is applied to the outer surface of a cuticle, which is mounted in a glass diffusion half‐cell. The cell wall surface is in contact with a receiver solution (20 mM citrate). Penetration is monitored by repeated sampling of the receiver solution. Droplets appeared dry on visual inspection within 1 h of application, but significant NAA penetration continued after droplet drying. Maximum rates of NAA penetration increased exponentially as temperature was increased (from 5 ° to 35 °C), the energy of activation averaging 153 (±11.6) kJ mol−1. At 35 °C, penetration reached a plateau within 10 h of application (at 91.1 (±1.0)% of dose applied) while at 5 °C penetration after 800 h reached only 30.2 (±7.5)%. Increasing relative humidity from 20 to 80% increased maximum rates [from 1.0 (±0.21) to 2.7 (±0.80)% h−1] and penetration at 120 h after application [from 36.8 (±2.1) to 64.3 (±3.7)%]. Rewetting deposits at 120, 240 and 360 h after application resulted in increased NAA penetration. However, amounts and rates of NAA penetration progressively decreased with each subsequent rewetting. Removal of deposits by cellulose acetate stripping at various times after droplet application resulted in a rapid decrease in NAA penetration. NAA penetration following deposit removal was always less than 6.1% of the amount of NAA applied and averaged 0.5 (±0.2)% when deposits were removed immediately after droplet drying.

© 2001 Society of Chemical Industry
Biological properties of the novel fungicide cyazofamid against Phytophthora infestans on tomato and Pseudoperonospora cubensis on cucumber
Authors: Mitani Shigeru , Araki Satoshi , Yamaguchi Tomona , Takii Yasuko , Ohshima Takeshi , Matsuo Norifusa
Published: August 2002

Cyazofamid (ISO proposed common name), 4‐chloro‐2‐cyano‐N,N‐dimethyl‐5‐p‐tolylimidazole‐1‐sulfonamide is a novel fungicide exhibiting specific activity against diseases caused by Oomycetes. In tests, cyazofamid at 0.4–1.6 mg litre−1 exhibited excellent preventative activity against Phytophthora infestans on tomato and Pseudoperonospora cubensis on cucumber. Minimum inhibitory concentrations of cyazofamid against both diseases were over 63 times lower than those of mancozeb and at least 16 times lower than those of metalaxyl. Cyazofamid at 1.6–25 mg litre−1 exhibited not only preventative activity, but also stable residual activity and rainfastness. Cyazofamid at 6.3 mg litre−1 reduced zoosporangia formation of P infestans and P cubensis on host plants by 100 and 94% respectively. Cyazofamid also exhibited translaminar and curative activity. Cyazofamid has a new mode of action for fungicides and exhibits no cross‐resistance with other currently registered and commonly used fungicides. These properties lead to a high level control by cyazofamid in field.

© 2001 Society of Chemical Industry
The relative toxicities of insecticides to earthworms of the Pheretima group (Oligochaeta)
Authors: Mostert Magdel A , Schoeman At S , Merwe Mac van der
Published: August 2002

An artificial soil test was used to determine the LC50values of carbaryl, chlorpyrifos, imidacloprid, cyfluthrin and fipronil against earthworms of the Pheretima group. For a 24‐h interval, carbaryl was the most toxic to earthworms (LC50 = 77 mg kg−1), followed by imidacloprid (155 mg kg−1), cyfluthrin (351 mg kg−1), chlorpyrifos (390 mg kg−1) and fipronil (>8550 mg kg−1) as the least toxic. For the 48‐h and 7‐day intervals, imidacloprid was the most toxic to earthworms (LC50 = 5 mg kg−1and 3 mg kg−1respectively), followed by carbaryl (16 mg kg−1; 9 mg kg−1), cyfluthrin (128 mg kg−1; 110 mg kg−1), chlorpyrifos (330 mg kg−1; 180 mg kg−1) and the least toxic was fipronil (>8550 mg kg−1both intervals). The surface application rates required to achieve these values are compared with the rates recommended for the control of turfgrass pests.

© 2002 Society of Chemical Industry
Brain neurotransmitter receptor binding and nootropic studies on Indian Hypericum perforatum Linn.
Authors: Kumar Vikas , Khanna V. K. , Seth P. K. , Singh P. N. , Bhattacharya S. K.
Published: August 2002

The high affinity binding sites for serotonin and benzodiazepine in the frontal cortex, for dopamine in the striatum and muscarinic cholinergic receptors in the hippocampus were investigated in the brains of Charles Foster rats treated for 3 days. Transfer latency on elevated plus maze (TL), passive and active avoidance behaviour (PA and AA) and electroconvulsive shock (ECS) induced amnesia were also studied. Pilot studies indicated that single dose administration of Indian Hypericum perforatum (IHp) had little or no acute behavioural effects and hence the extract of IHp was administered orally at two dose levels (100 and 200 mg/kg, p.o.) once daily for 3 consecutive days, while piracetam (500 mg/kg, i.p.), a clinically used nootropic agent, was administered acutely to rats as the standard nootropic agent. Control rats were treated with an equal volume of vehicle (0.3% carboxymethyl cellulose). The results indicate that IHp treatment caused a significant decrease in the binding of [3H] spiroperone (DA‐D2 receptor) to the striatum and an increase in the binding of [3H] ketanserin (5‐HT2A receptor) and [3H] flunitrazepam (BDZ receptor) to the frontal cortex in rats. Preliminary pharmacological studies with IHp extract indicate the presence of two major behavioural actions, namely, antidepressant and anxiolytic. The present findings tend to elucidate the mechanism of earlier observations, the downregulation of the dopamine D2 receptor being consonant with anxiolytic and the upregulation of 5‐HT2A and BDZ receptors being consonant with antidepressant activity. Piracetam when given alone, shortened the TL on days 1, 2 and 9 day and also antagonized the amnesic effects of ECS on the TL significantly, whereas IHp antagonized the amnesia produced by ECS. IHp had no significant effect per se on the retention of the PA in rats but produced a significant reversal of ECS induced PA retention deficit. Piracetam showed a significant facilitatory effect per se on PA retention and also reversed the ECS induced impaired PA retention. In the AA test, piracetam facilitated the acquisition and retention of AA in rats but IHp had no effect per se. Both the doses of IHp and piracetam significantly attenuated the ECS induced impaired retention of AA. These results indicate a possible nootropic action of IHp in amnesic animals, which was comparable qualitatively to piracetam. Copyright © 2002 John Wiley & Sons, Ltd.
Rotundifuran, a labdane type diterpene from Vitex rotundifolia, induces apoptosis in human myeloid leukaemia cells
Authors: Ko W. G. , Kang T. H. , Lee S. J. , Kim Y. C. , Lee B. H.
Published: August 2002

The inhibitory effect of rotundifuran, a labdane type diterpene isolated from the fruit of Vitex rotundifolia, on the proliferation of human myeloid leukaemia HL‐60 cells was examined. The concentration required for 50% inhibition of the growth after 96 h was 22.5 µM. The mode of cell death induced by rotundifuran was found to be apoptosis, which was judged by the morphological alteration of the cells and by the detection of DNA fragmentation using agarose gel electrophoresis. The degree of apoptosis was quantified by a sandwich enzyme immunoassay and flowcytometric analysis. These results suggest that rotundifuran may be used as a potential chemopreventive and chemotherapeutic agent. Copyright © 2001 John Wiley & Sons, Ltd.
Anticonvulsant Activities of the FS‐1 Subfraction Isolated from Roots of Delphinium denudatum
Authors: Raza Mohsin , Shaheen Farzana , Choudhary M. I. , Suria Amin , Rahman Atta‐ur‐ , Sombati Sompong , DeLorenzo R. J.
Published: August 2002

Delphinium denudatum Wall. (Ranunculaceae) is a medicinal herb used for the treatment of epilepsy in the subcontinent. The present study reports the anticonvulsant activities in the maximal electroshock test (MEST) and subcutaneous pentylenetetrazole (PTZ), bicuculline (BIC), picrotoxin (PIC)‐induced seizures of the FS‐1 subfraction (FS‐1) that was obtained by purification of an aqueous fraction isolated from the roots of D. denudatum. In CF 1 mice, FS‐1 (600 mg/kg i.p.) exhibited very potent anticonvulsant activity that was comparable to the effects of the well‐known antiepileptic drug phenytoin (20 mg/kg) in MEST and protected 100% animals from hind limb tonic extension phase of this model. FS‐1 also suppressed PTZ‐induced threshold seizure and the loss of the righting reflex with tonic fore and hind limb extension by 100%, similar to the antiepileptic drug valproic acid (350 mg/kg). BIC‐induced seizures were suppressed in 80% of the animals. FS‐1 exhibited weak anticonvulsant effect on PIC‐induced seizures, however, it significantly reduced mortality and delayed the onset of seizures. FS‐1 had no effect on strychnine (STN)‐induced extensor seizures. The results demonstrate the broad and potent anticonvulsant activity of the compounds in FS‐1 of D. denudatum. Copyright © 2001 John Wiley & Sons, Ltd.
Coleonema album: studies of the pharmacological action on smooth muscle in vitro and antimicrobial action of its essential oil
Authors: Lis‐Balchin Maria , Hart Stephen L.
Published: August 2002

The mode of action of the essential oil of Coleonema album, a South African species from the Cape region, was studied on smooth muscle in vitro using field‐stimulated guinea‐pig ileum. The oil produced an initial spasmogenic activity followed by spasmolysis, both actions being dose‐dependent. The spasmolytic action was post‐synaptic and not atropine‐like and was unaffected by the adrenoceptor blockers phentolamine and propranolol. There was no evidence for the involvement of either cyclic guanosine monophosphate or cyclic adenosine monophosphate in the spasmolytic activity. The oil had some calcium channel blocking activity but this is not the primary explanation for its spasmolytic response.

Antimicrobial activity against Pseudomonas aeruginosa, Escherichia coli, Staphyloccocus aureus and Saccharomyces cerevisiae was very low and totally absent against Enterococcus hirae, suggesting that the oil has no worthwhile potential in this area. However, as the oil has a very disagreeable odour in its undiluted form, it could be a powerful insect repellent, as its local usage suggests, and this remains to be investigated. Copyright © 2002 John Wiley & Sons, Ltd.
A fraction defective based capability index
Authors: Borges Wagner de Souza , Ho Linda Lee
Published: August 2002

Two problems greatly affect the use of capability indices such as $C_p$, $C_{pk}$ and $C_{pkm}$: the lack of affinity with the process fraction defective π and the difficulty of dealing with the sampling distributions of their natural estimators. In this paper, a capability index which is in one‐to‐one correspondence with π is introduced and simple inferential procedures under a Bayesian perspective are developed to facilitate its use in industrial applications. Copyright © 2001 John Wiley & Sons, Ltd.
Incorporation of solvent effects into density functional predictions of molecular polarizabilities and hyperpolarizabilities
Authors: Zhu Weihua , Wu Guo‐Shi , Jiang Yuansheng
Published: August 2002

A study of the effect of the field, the basis set, the functional, and the cavity size on molecular polarizabilities and hyperpolarizabilities of substituted benzenes in liquid or solution is reported. The calculations have been performed using the density functional theory (DFT) within the conductor‐like screening model (COSMO). The optimized computational parameters are adopted to calculate molecular polarizabilities and hyperpolarizabilities of substituted benzenes in liquid or solution. The results show good agreement with the experimental values. From comparison of the different theoretical results, it is found that at the same theoretical level, the selection of the different solvation models may play an important role in the calculations of molecular solvation polarizability, and using the same solvation model, the effects of the different theoretical methods are relatively small. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Electron correlation effects in ionic hydrogen clusters
Authors: Bokes P. , Štich I. , Mitas L.
Published: August 2002

We employ density functional, post‐Hartree–Fock, and quantum Monte Carlo methods to study the electronic structure, geometries, and behavior of positively charged Hm+ clusters with m=3,5,…,17. Their structure consists of a tightly bound H3+ core ion surrounded by successive solvation shells of H2 molecules. For the largest clusters, we propose new geometries. We find that correlated methods yield the stepwise decrease of enthalpies for dissociation of H2 from the clusters observed in experiments. Our best results are obtained by the diffusion Monte Carlo method, and by including finite temperature entropic effects, we are able to reproduce the experimental dissociation enthalpies with an unprecedented accuracy of less than 0.5 kcal/mol. These benchmark results contrast with erroneous predictions discovered in the density functional approaches. Finally, our analysis of the cluster energy surfaces indicates that under quantum and thermal fluctuations, the outer solvation shells will exhibit pronounced fluctional behavior. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 86–95, 2001
Quantum mode phonon forces between chainmolecules
Authors: Bohr Jakob
Published: August 2002

A phenomenological description of the contributions of phonons to molecular force is developed. It uses an approximation to consider macromolecules as solid continua. The molecular modes of a molecule can then be characterized by a Debye‐like description of the partition function. The resulting bimolecular interaction is a truly many‐body force that is temperature dependent and can be of the order of 1 eV. These phonon forces depend on molecular shape, composition, and density. They may therefore also be important for large molecular conformational changes, including the unfolding of chain molecules. For the later case, a significant change in zero‐point energy is found. This may be the underlying cause for cold denaturation of proteins. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 249–252, 2001
Noncollinear spin density functional theory for spin‐frustrated and spin‐degenerate systems
Authors: Yamanaka S. , Yamaki D. , Shigeta Y. , Nagao H. , Yamaguchi K.
Published: August 2002

We have implemented ab initio linear combinations of Gaussian‐type orbital calculations with generalized localized spin density approximation (GLSDA) for a dimer of equilateral H3 as a model of the noncollinear magnetic clusters. It has been found that the GLSDA solution with the three‐dimensional noncollinear spin structure is, contrary to prior band calculations by other groups, the ground state near the Oh conformation. Further computational results are compared to that of ab initio generalized Hartree–Fock. The difference between them and the influence of the correlation correction were discussed. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
A cylindrical capacitor ionization source: droplet generation and controlled charge reduction for mass spectrometry
Authors: Ebeling Daniel D. , Westphall Michael S. , Scalf Mark , Smith Lloyd M.
Published: August 2002

A cylindrical capacitor ionization source was used in conjunction with corona discharge charge reduction for generation of singly charged ions for mass spectrometric analysis. The source consists of a fused‐silica capillary threaded with a platinum wire and placed inside a stainless steel tube. Application of an electric potential to the wire results in the production of a linear stream of charged droplets when an aqueous solution is pumped through the capillary. Subsequent solvent evaporation yields ions, providing a continuous ion source for mass spectrometry. Passage of the ions through a corona discharge charge reduction chamber permits reduction of the charge state to predominantly singly charged species, facilitating analysis of DNA and protein mixtures. The change from production of multiply charged ions to production of singly charged ions is extremely simple, requiring only modulation of the voltage applied to the corona discharge electrode. A simple technique for construction of the ionization source is reported. Copyright © 2001 John Wiley & Sons, Ltd.
High‐throughput cytochrome P450 (CYP) inhibition screening via a cassette probe‐dosing strategy. VI. Simultaneous evaluation of inhibition potential of drugs on human hepatic isozymes CYP2A6, 3A4, 2C9, 2D6 and 2E1
Authors: Bu Hai‐Zhi , Magis Lisa , Knuth Kim , Teitelbaum Philip
Published: August 2002

The inhibition potential of drugs towards five major human hepatic cytochrome P450 (CYP) isozymes (CYP2A6, 3A4, 2C9, 2D6, and 2E1) was investigated via cassette dosing of the five probe substrates (coumarin, midazolam, tolbutamide, dextromethorphan, and chlorzoxazone) in human liver microsomes using a 96‐well plate format. After microsomal incubations had been terminated with formic acid, the five marker metabolites (7‐hydroxycoumarin, 1′‐hydroxymidazolam, 4‐hydroxytolbutamide, dextrorphan, and 6‐hydroxychlorzoxazone) were simultaneously quantified using direct injection/online guard cartridge extraction/tandem mass spectrometry (DI‐GCE/MS/MS). Several advantages resulted from the use of a short C18 guard cartridge (4 mm in length) for DI‐GCE/MS/MS, including minimal sample preparation, fast online extraction, short analysis time (2.5 min), and minimal source contamination. In addition, this method demonstrated an inter‐day accuracy range from −8.7 − 7.4% with a precision less than 8.3% for the quantification of all the marker metabolites. The inhibition assay for the five CYP isozymes was evaluated using their known selective inhibitors via individual and cassette dosing of the probe substrates. The IC50 values measured via cassette dosing were consistent with those observed via individual dosing, which were all in agreement with the reported values. In addition, the validated assay was used to evaluate the inhibitory potential of 23 generic drugs (randomly selected) towards the five CYP isozymes. The results suggest the integration of the cassette dosing strategy and the DI‐GCE/MS/MS method can provide a reliable in vitro approach to screening the inhibitory potential of new chemical entities, with maximal throughput and cost‐effectiveness, in support of drug discovery and development. Copyright © 2001 John Wiley & Sons, Ltd.
Ammonia chemical ionization tandem mass spectrometry in structural determination of alkaloids. II. Tetraponerines from pseudomyrmecine ants
Authors: Garraffo H. Martin , Spande Thomas F. , Jain Poonam , Kaneko Tetsuo , Jones Tappey H. , Blum Murray S. , Ali T. M. Musthak , Snelling Roy R. , Isbell Lynne A. , Robertson Hamish G. , Daly John W.
Published: August 2002

Chemical ionization tandem mass spectrometry (CI‐MS/MS) of alkaloids with ammonia reagent gas and collision‐activated dissociation as well as EI‐MS/MS were applied to the tetraponerine alkaloids in extracts from six pseudomyrmecine ants of the genus Tetraponera. The MS/MS techniques along with gas chromatography Fourier transform infrared (GC/FTIR) spectra allowed identification in two extracts of seven of the eight known tetraponerines. The EI‐MS/MS fragmentations proved diagnostic for the ring system and the CI‐MS/MS patterns for the C‐8 or C‐9 substitution, while the Bohlmann bands in FTIR spectra were diagnostic for the C‐8 or C‐9 configurations. An Indian ant (T. allaborans) had T–2, T–4 and T–8, while a Chinese ant (T. binghami) had T–5, T–6, T–7 and T–8. Four other ants, T. rufonigra (India), T. penzigi (Africa), T. clypeata (Africa) and T. sp. cf. emeryi (Africa), had no tetraponerines. Copyright © 2001 John Wiley & Sons, Ltd.
Direct determination of phosphorylated intracellular anabolites of stavudine (d4T) by liquid chromatography/tandem mass spectrometry
Authors: Pruvost Alain , Becher François , Bardouille Patrick , Guerrero Catherine , Creminon Christophe , Delfraissy Jean‐François , Goujard Cécile , Grassi Jacques , Benech Henri
Published: August 2002

The objective was to develop and validate a routine assay for active intracellular anabolites of stavudine (d4T), a nucleoside reverse transcriptase inhibitor in human PBMC, applicable to pharmacokinetic studies and treatment monitoring. This was achieved using liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS), which theoretically allies optimum sensitivity, specificity and high sample throughput. After cellular lysis in a Tris/methanol buffer, the extract spiked with 2[H8]‐ATP (internal standard) is directly injected into the LC/MS/MS system. Phosphorylated metabolites of d4T as well as deoxythymidine‐triphosphate, the competitor on the reverse transcriptase, are separated from d4T on a reverse‐phase microbore column with ion pairing. The detection is performed in the multiple reaction monitoring (MRM) mode after drug ionisation in negative mode electrospray. The limit of quantitation for d4T‐TP was 138 fmol per 7 mL blood (9.8 fmol per 106 cells) and CV% for repeatability and intermediate precision were lower than 15%. Stability of compounds was checked before and during the process of isolation of PBMC. Cellular samples from several d4T‐treated patients were successfully analysed using this method and d4T‐triphosphate and deoxythymidine triphosphate were recovered. In conclusion, we have developed and validated a routine LC/MS/MS method that allows the simultaneous determination of mono‐, di‐ and triphosphorylated anabolites of d4T in PBMC as well as the natural corresponding triphosphate in one analysis. For the first time, the chain terminator ratio (d4T‐TP/dT‐TP) could be directly measured. This method can be used simply and routinely on more than 35 samples per day. Extension to other nucleoside analogues is under development. Copyright © 2001 John Wiley & Sons, Ltd.
Structural analysis of oligosaccharides by atmospheric pressure matrix‐assisted laser desorption/ionisation quadrupole ion trap mass spectrometry
Authors: Creaser Colin S. , Reynolds James C. , Harvey David J.
Published: August 2002

An ion source incorporating a fibre optic interface has been constructed for atmospheric pressure matrix‐assisted laser desorption/ionisation quadrupole ion trap mass spectrometry. The configuration has been applied to the study of linear and complex oligosaccharides. Multi‐stage tandem mass spectrometry (MSn, n = 2–4) experiments carried out in the ion trap enable extended fragmentation pathways to be investigated that yield structural information. Collisional activation of sodiated oligosaccharides, as demonstrated on the model compound maltoheptaose, produces primarily B and Y fragments resulting from cleavage of glycosidic bonds; fragments from cross‐ring cleavages are also observed following further stages of tandem mass spectrometry, providing additional linkage information. The analyses of mixtures of complex oligosaccharides are demonstrated for N‐linked glycans from chicken egg glycoproteins and a ribonuclease glycan mixture. Mass spectrometric and tandem mass spectrometric data for sugars with molecular weights up to 4000 Da is shown for mixtures of linear dextrans and N‐linked glycans. The use of MSn (n = 3, 4) on these complex molecules enabled structural information to be elucidated that confirms data observed in the MS/MS spectra. Copyright © 2001 John Wiley & Sons, Ltd.
Quantitation in gradient high performance liquid chromatography/inductively coupled mass spectrometry investigated using diclofenac and chlorpromazine
Authors: Duckett Catherine J. , Bailey Nigel J. C. , Walker Heather , Abou‐Shakra Fadi , Wilson Ian D. , Lindon John C. , Nicholson Jeremy K.
Published: August 2002

The use of directly coupled high performance liquid chromatography/inductively coupled plasma mass spectroscopy (HPLC/ICPMS) employing chlorine (35Cl/37Cl) detection has been investigated with respect to the detection and quantitation of the drugs diclofenac and chlorpromazine. By integration of peak areas in the ‘chloratogram’ (the chlorine‐specific HPLC chromatogram), a calibration curve was constructed, from which the concentrations could be determined. Chlorine‐detected HPLC/ICPMS is quantitative over a wide range of concentrations of pharmaceutical relevance for metabolite detection and the results reproducible (standard deviation ± 0.43%) over multiple injections. Application of gradient chromatography and variation in the bulk mobile phase physicochemical properties has little effect on the ICPMS detection response for these compounds. This work indicates that the use of HPLC/ICPMS is likely to be quantitatively reliable for metabolism studies for a range of chlorinated xenobiotics. Copyright © 2002 John Wiley & Sons, Ltd.
Molecular techniques should not now replace cell culture in diagnostic virology laboratories
Authors: Ogilvie Marie
Published: August 2002

The value of molecular techniques for virology is not in dispute; the issue debated here is whether or not to abandon virus isolation altogether. Modern clinical virology relies on rapid virus detection for timely infection control and antiviral therapy. The role of virus isolation, inevitably a slower process as it involves replication in cell cultures, is most significant in providing epidemiological data, in the diagnosis of new or unexpected infection, and in yielding infectious virus for further study. Examples include identification of enterovirus serotypes in outbreaks, diagnosis of atypical virus infections, and provision of virus isolates for phenotypic antiviral susceptibility assays. Many viruses can be detected after overnight culture using the centrifugation‐enhanced (shell vial) technique. In contrast to this established track record, the commercial development of molecular assays has been concentrated on blood‐borne viruses, and standardisation of procedures for other viruses is lacking. Accreditation of molecular techniques is just beginning, and few external quality assurance schemes are available yet. In my view, it is premature to abandon routine virus isolation, although as molecular diagnosis expands, the facilities for cell culture and isolation work may become more centralised to retain expertise and to provide the range and quality of service required. Copyright © 2001 John Wiley & Sons, Ltd.
Flow management strategies to control blooms of the cyanobacterium, Anabaena circinalis, in the River Murray at Morgan, South Australia
Authors: Maier Holger R. , Burch Michael D. , Bormans Myriam
Published: August 2002

The Murray–Darling river system is highly regulated and is Australia's major surface water resource. It is subject to blooms of the toxic cyanobacterium Anabaena circinalis, which present significant water quality problems. As a result of these blooms, an algal management strategy has been developed for the Murray–Darling basin. One of the major objectives of the strategy is the development of flow management strategies for key reaches of the river system. Intensive studies in the Murrumbidgee River, Australia, have indicated that persistent thermal stratification is a requirement for blooms of this cyanobacterium to occur. In the lower Murray, mean wind speed was found to be the major factor affecting the degree of thermal stratification under low flow conditions, which generally exist during the months of December to March. In this paper, the effect of various flow management scenarios on the likelihood of the occurrence of blooms in the River Murray at Morgan, South Australia, are assessed. A frequency analysis is carried out on 30 years of wind speed data to determine the probability of occurrence of persistent thermal stratification under a number of flow regimes. The scenarios evaluated include existing base flow conditions, altered base flow regimes, temporary releases from an upstream storage (Lake Victoria) and the temporary reduction of weir pool levels. The results obtained indicate that the dispersal of existing blooms by simultaneously reducing the weir pool levels at Locks 1–3 is the most effective and economical strategy for combating bloom formation by A. circinalis in the River Murray at Morgan. Copyright © 2001 John Wiley & Sons, Ltd.
“It's harder than we thought it would be”: A comparative case study of expert–novice experimentation strategies
Authors: Hmelo‐Silver Cindy E. , Nagarajan Anandi , Day Roger S.
Published: August 2002

Scientific inquiry is a complex skill. Aspiring physicians need to learn these skills so that they can be educated consumers of medical research as well as being collaborators in different kinds of clinical trials. But school science often fails to provide the kind of authentic tasks needed to help students develop appropriate reasoning skills and epistemological beliefs. In this study, we compared a group of expert cancer researchers with four groups of fourth year medical students (the “novice” groups) engaged in the task of designing a clinical trial to test a new cancer drug using a computer‐based modeling tool, the Oncology Thinking Cap. Although the experts and novices reached similar endpoints, their reasoning processes differed considerably. For the experts, this was a task that required learning about the drug they were testing. The novices needed to learn about designing clinical trials, particularly about how variables interacted with each other, as well as learning about the drug. One of the major lessons learned by the novice student groups was just how complex clinical trial design really is. © 2002 Wiley Periodicals, Inc. Sci Ed 86:219–243, 2002; DOI 10.1002/sce.10002
The role of ideational networks in laboratory inquiry learning and knowledge of evolution among seventh grade students
Authors: Anderson O. Roger , Randle David , Covotsos Tom
Published: August 2002

Ideational networks were assessed based on written narrative of seventh grade students who had begun a unit on evolution. The amount of ideational network linkages in narrative, elicited by showing the students a diagram of an evolutionary branching tree of life, was analyzed using flow‐map techniques. The number of network linkages in the students' narrative was positively correlated with mean scores on subsequent inquiry laboratory work on evolution (r = 0.5, p ≪ .01). final unit test score on knowledge of biological evolution (r = 0.35, p < .01), and the extent of correct conceptions about evolution contained in the students' written essays as determined by content analyses (r = 0.7, p ≪ .01). Students, who scored high on the content analyses of their written narrative and whose narrative contained extensive ideational network linkages, also tended to use a logical sequential rule of ordering their thoughts based on a phylogenetic principle of evolutionary change accompanying increasing complexity of life (i.e., progression from one‐celled organisms to complex multicelled organisms). Moreover, the mean frequency of occurrences of higher level categorical thought in narrative increased with increasing amount of ideational linkages in recall. © 2001 John Wiley & Sons, Inc. Sci Ed 85:410–425, 2001.
Non‐equilibrium intergranular segregation and embrittlement in neutron‐irradiated ferritic alloys
Authors: Kameda J. , Nishiyama Y. , Bloomer T. E.
Published: August 2002

This study describes intergranular segregation and embrittlement in several model ferritic alloys doped with Mn, P, S and/or Cu subjected to neutron irradiation, irradiation‐equivalent thermal ageing (ETA) and post‐irradiation annealing (PIA). Neutron irradiation produced a larger amount of intergranular phosphorus segregation than sulfur segregation. Irradiation‐induced phosphorus segregation became more prominent with decreasing bulk phosphorus content. Intergranular carbon segregation remained small in all the as‐irradiated alloys, which was enhanced by the ETA except for the high phosphorus‐containing alloy. A PIA study has shown that the phosphorus segregation in phosphorus‐doped alloys subjected to lower temperature PIA proceeds via mobile phosphorus–interstitial complexes, whereas the sulfur segregation, which occurs over a wide PIA temperature range, is controlled by vacancy‐enhanced diffusion. The mechanisms of non‐equilibrium intergranular segregation induced by neutron irradiation are discussed in light of coupled fluxes of point defects and impurities and changes in the segregation capacity of grain boundaries. Small punch tests demonstrated how the impurity segregation or desegregation and hardening or softening induced by the irradiation, ETA and PIA influence intergranular embrittlement in the various ferritic alloys. Copyright © 2001 John Wiley & Sons, Ltd.
X‐ray photoelectron spectroscopy study of the interface formed between chromium and 4,4′‐bis (4‐dimethylaminostyryl) benzene
Authors: deVos S. A. , Nguyen T. P. , Ip J. , Rendu P. Le , Tran V. H.
Published: August 2002

Chromium interfaces with 4,4′‐bis(4‐dimethylaminostyryl) benzene (DMASB) were examined using x‐ray photoelectron spectroscopy (XPS). Deposition of the metal on the organic or the organic on the metal under different physical conditions caused major differences in the chemical composition of the interface that could have implications in the injection of charge via the interface into the organic. There is evidence of the formation of a form of chromium carbide or chromium–oxygen–carbon complex and a form of chromium oxynitride at the DMASB/Cr interface. At the Cr/DMASB interface, only a form of chromium oxynitride was observed. Copyright © 2001 John Wiley & Sons, Ltd.
Infrared microspectroscopic studies on the pitting of AA2024‐T3 induced by acetone degreasing
Authors: Chidambaram Devicharan , Halada Gary P.
Published: August 2002

Acetone degreasing of aluminum alloy AA2024‐T3, as per the ASTM E1078‐97 cleaning protocol, showed that copper‐rich intermetallic particles acted as a photocatalyst in the presence of moisture to convert the acetone remaining on the surface to acetic acid. In this work, using synchrotron infrared microspectroscopy (SIRMS), we have investigated further the acetone‐induced pitting of AA2024‐T3 that was shown earlier using XPS. Using SIRMS prior to sodium chloride mist exposure shows the presence of carboxyl groups at sites where pitting is initiated, indicating that pitting is induced by acetone. The infrared linescan and mapping performed on acetone‐degreased AA2024‐T3 exposed to sodium chloride mist shows the presence of acetyl groups surrounding the pits. Based on this work, acetone is not recommended for degreasing aluminum–copper alloys. Copyright © 2001 John Wiley & Sons, Ltd.