bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular dynamics of HIV‐1 reverse transcriptase indicates increased flexibility upon DNA binding
Authors: Madrid Marcela , Lukin Jonathan A. , Madura Jeffry D. , Ding Jianping , Arnold Edward
Published: August 2002

HIV‐1 reverse transcriptase (RT) is one of the main targets for drugs used in the treatment of AIDS, among them, the non‐nucleoside RT inhibitors (NNRTIs). The flexibility of RT unliganded and complexed to double‐stranded DNA (RT/dsDNA), in water, has been studied by means of molecular dynamics. The simulations show that RT flexibility depends on its ligation state. The RT/dsDNA trajectories show larger fluctuations in the atomic positions than uncomplexed RT, particularly at the tips of the p66 fingers and thumb subdomains. This increased flexibility is consistent with the ability of the p66 fingers of the RT/dsDNA complex to close down after the binding of a deoxynucleoside triphosphate (dNTP) molecule, as observed in the crystal structures of RT/dsDNA bound to dNTP. The two complexation states present different patterns of concerted motions, indicating that the bound dsDNA alters RT flexibility. The motions of amino acid residues that form the non‐nucleoside RT inhibitor binding pocket upon complexation with a NNRTI are anticorrelated with the p66 fingers (in RT/dsDNA) and correlated to the RNase H subdomain (unliganded RT). These concerted motions indicate that binding of a NNRTI could alter the flexibility of the subdomains whose motions are correlated to those of the binding pocket. Proteins 2001;45:176–182. © 2001 Wiley‐Liss, Inc.
Involvement of cytochrome P‐450 enzyme activity in the selectivity and safening action of pyrazosulfuron‐ethyl
Authors: Yun Min Soo , Shim Ie Sung , Usui Kenji
Published: August 2002

To investigate the selectivity and safening action of the sulfonylurea herbicide pyrazosulfuron‐ethyl (PSE), pyrazosulfuron‐ethyl O‐demethylase (PSEOD) activity involving oxidative metabolism by cytochrome P‐450 was studied in rice (Oryza sativa L cv Nipponbare) and Cyperus serotinus Rottb. Cytochrome P‐450‐dependent activity was demonstrated by the use of the inducers 1,8‐naphthalic anhydride and ethanol, the herbicides PSE, bensulfuron‐methyl, dimepiperate and dymron, or the inhibitor piperonyl butoxide (PBO). Growth inhibition in C serotinus seedlings was more severe than that in rice seedlings. O‐Dealkylation activities of PSE were induced differently in rice and in C serotinus, with distinctly higher activity in rice seedlings. The induced PSEOD activities were slightly inhibited by PBO in rice seedlings, whereas they were strongly inhibited in C serotinus seedlings. Dimepiperate and dymron were effective safeners of rice against PSE treatment. Treatments with herbicide alone resulted in less induction of PSEOD activity compared with combined treatments of the herbicide and safener. PSEOD activity in rice seedlings induced with herbicide alone was strongly inhibited by PBO, whereas it was weakly inhibited in rice seedlings induced with combinations of PSE and two safeners. These results suggest that O‐demethylation by cytochrome P‐450 enzymes may be involved in the metabolism of PSE and may contribute to its selectivity and safening action. Furthermore, these results suggest the existence of a multiple form of cytochrome P‐450 in plants.

© 2001 Society of Chemical Industry
Photolysis of pesticides: influence of epicuticular waxes from Persica laevis DC on the photodegradation in the solid phase of aminocarb, methiocarb and fenthion
Authors: Pirisi Filippo M , Angioni Alberto , Cabizza Maddalena , Cabras Paolo , Cao Clara Falqui
Published: August 2002

Pesticides with N,N‐dimethyl and thiomethyl moieties (aminocarb, methiocarb and fenthion) were irradiated under artificial light (λ > 290 nm) in an amorphous wax phase from Persica laevis DC. The effect of the presence of the wax on the photolysis rate differed in the three pesticides, increasing it in aminocarb, having little effect in methiocarb and slowing it down in fenthion. The presence of the wax affected the qualitative photodegradation behaviour of all the pesticides. The data obtained were compared with those for pirimicarb, which had been studied earlier.

© 2001 Society of Chemical Industry
Neonicotinoid insecticides alter diapause behavior and survival of overwintering white grubs (Coleoptera: Scarabaeidae)
Authors: Grewal Parwinder S , Power Kevin T , Shetlar David J
Published: August 2002

The chloronicotinyl, imidacloprid, and the thianicotinyl, thiamethoxam, are effective insecticides against white grubs when applied as preventative treatments during or immediately after egg laying. Their efficacy sharply declines when the grubs reach late‐instar stage. As both imidacloprid and thiamethoxam act on post‐synaptic nicotinic acetylcholine receptors and modify insect behavior, we hypothesized that the two compounds will interfere with overwintering behavior of scarabs, thus reducing their ecological fitness and exposing them to increased winter mortality. We tested this hypothesis by applying the two compounds curatively against late second‐instar and early third‐instar Popillia japonica and Cyclocephala borealis grubs in turfgrass. Imidacloprid provided control of P japonica equivalent to the most widely used curative organophosphate, trichlorfon, by 14 days after treatment, but thiamethoxam had no affect. In contrast, both imidacloprid and thiamethoxam caused significant reductions in C borealis populations. Both insecticides altered the overwintering behavior of P japonica by significantly reducing the normal downward movement of grubs in October. Halofenozide, an ecdysone agonist, also caused rapid mortality of the late second‐instar C borealis equivalent to trichlorfon, but had no affect on P japonica. In another experiment on a site naturally infested with entomopathogenic nematodes, the exclusive treatment of third‐instar P japonica with imidacloprid resulted in no significant mortality in the autumn (up to 15 days after treatment), but caused a significant reduction in the survival of overwintered grubs. There was an increase in the numbers of grubs infected with nematodes in the imidacloprid and trichlorfon treatments compared with control, but these differences were significant only for trichlorfon. These results indicate that imidacloprid can effectively control late second‐instars of both P japonca and C borealis and can significantly reduce survival of overwintered third‐instar P japonica by altering their normal overwintering behavior.

© 2001 Society of Chemical Industry
An ecological risk assessment for spinosad use on cotton
Authors: Cleveland Cheryl B , Mayes Monte A , Cryer Steven A
Published: August 2002

Spinosad is a reduced‐risk insecticide with a novel mode of action that provides an alternative to older classes of insecticides such as organophosphates, carbamates and pyrethroids. A comprehensive ecological risk assessment for spinosad use in US cotton crops is presented within a framework of tiered levels of refinement following the guidelines of the US EPA for ecological risk assessments. Toxicity information for a variety of species is documented and utilized, environmental concentrations estimated, and risk characterizations in the form of risk quotients are quantified. Results indicate that spinosad use in cotton does not exceed the most conservative Tier I levels of concern (LOC) values for groundwater, mammals and birds or acute risk to aquatic organisms. Use of very conservative Tier I screening methods resulted in exceeding LOC values for chronic exposure for some aquatic organisms, thus prompting further refinement. When the exposure prediction was refined using less conservative, Tier II mechanistic environmental fate transport models to predict off‐site transport and environmental concentrations, chronic risk was not predicted for these species. Spinosad is acutely toxic to bees under laboratory conditions, but toxicity of residue studies and field studies indicate that under actual use conditions the impact on bees is minimal.

© 2001 Society of Chemical Industry
Fumigant activity of (E)‐anethole identified in Illicium verum fruit against Blattella germanica
Authors: Chang Kyu‐Sik , Ahn Young‐Joon
Published: August 2002

The insecticidal activities of materials derived from the fruit of star anise, Illicium verum, against adults of Blattella germanica were examined by direct contact application and fumigation methods, and compared with those of DDVP, deltamethrin and hydramethylnon. The biologically active constituent of the Illicium fruit was characterized as the phenylpropene, (E)‐anethole, by spectroscopic analysis. In a filter paper diffusion test with females, (E)‐anethole caused 80.3% mortality at 0.159 mg cm−2 at 1 and 3 days after treatment (DAT), whereas 16.7% mortality at 3 DAT was achieved at 0.079 mg cm−2. DDVP and deltamethrin gave >90% mortality at 0.019 mg cm−2 at 1 DAT. At 0.009 mg cm−2, DDVP and deltamethrin showed 73.3 and 60% mortality at 1 DAT, respectively, but 93.3 and 76.7% mortality at 3 DAT. Hydramethylnon exhibited 0 and 93.3% mortality at 0.159 mg cm−2 at 1 and 3 DAT, respectively, whereas 6.7% mortality at 3 DAT was observed at 0.079 mg cm−2. In a fumigation test with females, (E)‐anethole was much more effective in closed cups than in open ones, indicating that the insecticidal activity of the compound was largely attributable to fumigant action. (E)‐Anethole and DDVP caused 100% mortality at 0.398 and 0.051 mg cm−2 4 and 1 h after treatment, respectively. (E)‐Anethole showed 46.7% mortality at 0.199 mg cm−2 at 3 DAT, whereas deltamethrin and hydramethylnon at 0.796 mg cm−2 was ineffective for 3‐day period. As naturally occurring insect‐control agents, the I verum fruit‐derived materials described could be useful for managing populations of B germanica.

© 2001 Society of Chemical Industry
Discharge consents in Scotland
Authors: Rosie Andrew J , Singleton Peter T R
Published: August 2002

The Scottish Environment Protection Agency (SEPA) is charged with the protection of the Scottish environment, and this is achieved through the regulation of polluting discharges and through consulting, influencing and educating others who interact with it. This paper describes aspects of the agency's regulatory work as it applies to the Scottish fish‐farming industry. By far the largest sector of the industry in Scotland involves the rearing of fin‐fish in cages, presently still dominated by Atlantic salmon, and the paper is based on experiences gained within this sector. The present circumstances affecting its development are described with reference to the environmental impacts associated with cage‐rearing techniques used for production in marine waters. This paper briefly reviews the statutory background behind Scotland's system of discharge consents, including relevant aspects of European legislation. Methods developed to control the environmental risks posed by sea louse treatment chemicals are described. The concept of farming the sea is explored in relation to SEPA's ‘allowable zone of effects’ approach and the growing public concern about perceived environmental damage. Finally, the future prospects for the industry in Scotland are reviewed in relation to sea louse control.

© 2002 Society of Chemical Industry
Solid‐phase synthesis of a dendritic peptide related to a retinoblastoma protein fragment utilizing a combined boc‐ and fmoc‐chemistry approach
Authors: Cavallaro Vittoria , Thompson Philip , Hearn Milton
Published: August 2002

Dendritic peptides, often presented as multiple antigen peptides (MAPs), are widely used in immunological‐based fields of research, although their synthesis can be extremely challenging. In this paper, a tetrameric dendritic MAP‐like presentation of the retinoblastoma protein [649‐654] sequence (4RB649‐654) has been prepared using solid‐phase peptide synthesis (SPPS) methods. During the synthesis of this dendritic molecule, numerous modifications to the synthetic protocols were examined. These modifications included the introduction of a combination Boc‐ and Fmoc‐chemistry approach and also the use of 1,8‐diazabicyclo[5.4.0]‐undec‐7‐ene as a Fmoc‐deprotection agent. The use in combination of Boc‐ and Fmoc‐based synthetic strategies resulted in the production of the desired peptide molecule, 4RB649‐654, in high purity and acceptable yields following purification by reversed phase HPLC. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis of oligopeptides with the sequence SXWS and their chemotactic effects on a ciliated protozoan Tetrahymena pyriformis
Authors: Illyés Eszter , Hudecz Ferenc , Köhidai László , Láng Orsolya , Szabó Pál , Sebestyén Ferenc
Published: August 2002

In this paper, the solid phase synthesis and chemical characterization of members of an SXWS sub‐library (SAWS, SDWS and SKWS) as well as the comparison of their chemotactic properties with those of SEWS, which exhibits a prominent effect at 10−12 M on a ciliated protozoan, Tetrahymena pyriformis, are described. We found that the chemotaxis of cells induced with the SXWS peptides varied according to the nature of the amino acid residue (Ala, Asp, Lys) in position X. The chemotactic activity of SEWS was not surpassed by any of three new tetrapeptides, although SAWS was also chemoattractant. Interestingly, SDWS, with an acidic side chain at position X, could not elicit any chemotactic response. SKWS, however, showed mild but significant chemorepellent activity over a wide concentration range. Chemotactic selection studies showed that the two chemoattractant peptides (SAWS and SEWS) had an expressed ability to select high‐responder offspring cell populations. Peptides with neutral (SDWS) or chemorepellent (SKWS) properties were not able to select such subpopulations from the mixed cultures of Tetrahymena, indicating that the chemotactic response elicited by SXWS peptides is ligand‐specific. For ligand‐binding experiments N‐terminally labelled fluorescent derivatives of SXWS peptides were prepared, applying [4‐[7‐hydroxycoumaryl]]acetic acid (Hca‐OH) or 4‐ethoxymethylene‐2‐[1]‐naphthyl‐5(4H)‐oxazolone (naOx‐OEt) as markers. Hca‐OH was introduced using an active ester technique as the last step of SPPS, or after cleavage in solution. The oxazolone naOx‐OEt reacted with the amino group of the peptide by liberation of EtOH. The binding characteristics of fixed Tetrahymena cells with the naOx‐labelled peptides showed good correlation between binding profiles and chemotactic responsiveness (SEWS > SAWS > SDWS ∼ SKWS). A similar binding pattern was observed in the case of Hca‐peptides (SEWS > SAWS > SDWS). Hca‐SKWS, however, bound remarkably to the cell surface. The binding activity of the Hca‐peptides was less pronounced than that of the naOx‐peptides, indicating the importance of the fluorophores applied. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Passive control technologies for seismic‐resistant buildings in Europe
Authors: Mazzolani Federico M
Published: August 2002

A bird's‐eye view of the main passive control technologies used in European earthquake‐prone countries for seismic protection of civil buildings is presented. After some remarks on the general situation in Europe, which identify Italy as a leading country in this field, the special types of devices used in passive control technologies are analysed. Some relevant examples of applications are illustrated, both for seismic protection of new buildings and for rehabilitation of existing buildings. Current developments in codification (design codes and guidelines) are also examined. Finally, an overview of recent European research projects recognise some interesting issues, which promise future improvements in passive control technology.
Effect of the traditional medicinal plants Rhazya stricta, Balanitis aegyptiaca and Haplophylum tuberculatum on paracetamol‐induced hepatotoxicity in mice
Authors: Ali B. H. , Bashir A. K. , Rasheed R. A.
Published: August 2002

This work examines the effects of lyophilized extracts of the medicinal plants Rhazya stricta, Balanites aegyptiaca and Haplophylum tuberculatum on liver damage induced by paracetamol in mice. Rapid HPLC finger prints for some of these extracts were made. The hepatoprotective effects of the plant extracts were compared with that of the standard hepatoprotective agent silymarin. The extracts (1 g/kg) and silymarin (0.1 g/kg) were given orally for 5 consecutive days .On the last day of treatment a hepatotoxic oral dose of paracetamol (0.6 g/kg) was given, and 3 h later, the hepatic function of mice was evaluated using pentobarbitone ‐induced sleeping time, the concentration of reduced glutathione (GSH) in liver, and the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ‐glutamyl transferase (GGT) and cholesterol concentration in plasma. The livers were weighed and examined for macro‐ and microscopic changes. Pretreatment with R. stricta or with silymarin protected the livers of treated mice against paracetamol hepatotoxicity as evidenced by a significant improvement of the above liver function tests. B. Aegyptiaca had a relatively modest hepatoprotective activity, while H. tuberculatum was almost ineffective.

Oral pretreatment of mice for 5 consecutive days with an extract of R. stricta or silymarin protected about 57% and 92% of the treated mice, respectively, against the lethal effect of paracetamol (1 g/kg). B. aegyptiaca and H. tuberculatum protected only 27% and 16% of the animals, respectively. Copyright © 2001 John Wiley and Sons, Ltd.
The effect of Polbax extract on lipofuscin accumulation in cultured neonatal rat cardiac myocytes
Authors: Terman Alexei , Brunk Ulf T.
Published: August 2002

Polbax®, a water‐soluble extract of fresh pollen grains and pistils, was tested for its ability to influence the accumulation of lipofuscin (age pigment) in cultured neonatal rat cardiac myocytes. Exposure for 3 weeks to Polbax at concentrations of 0.1, 1.0 or 10 mg/L decreased lipofuscin accumulation morphometrically assayed using laser scanning microscopy images (green excitation light) of formaldehyde‐fixed cells, by 24%, 41% or 43%, respectively. Based on the knowledge that oxidative stress and iron‐catalysed peroxidation play an important role in lipofuscinogenesis, we suggest that Polbax may slow lipofuscin formation due to antioxidant activities, perhaps involving intralysosomal dismutation of superoxide produced by autophagocytosed mitochondria and/or iron‐chelation. Copyright © 2002 John Wiley & Sons, Ltd.
Antimicrobial properties of the essential oil of Artemisia asiatica Nakai
Authors: Kalemba D. , Kusewicz D. , Świa̧der K.
Published: August 2002

The antibacterial and antifungal activity of the essential oil of Artemisia asiatica Nakai, its main constituents: 1,8‐cineole and selin‐11‐en‐4α‐ol and monoterpene alcohols fraction were determined against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, Rhodotorula rubra and Aspergillus fumigatus. The oil exhibited a good inhibitory activity against bacteria and fungi. The monoterpene alcohols fraction showed the highest antibacterial activity. Copyright © 2002 John Wiley & Sons. Ltd.
Synthesis of plumbagin derivatives and their inhibitory activities against Ehrlich ascites carcinoma in vivo and Leishmania donovani Promastigotes in vitro
Authors: Hazra Banasri , Sarkar Rajes , Bhattacharyya Saswati , Ghosh Prabir K. , Chel Gautam , Dinda Biswanath
Published: August 2002

Plumbagin, a plant‐derived bioactive naphthoquinonoid compound, was converted to a hydroquinonoid derivative, which was studied for its tumour‐inhibitory and antileishmanial activities for the first time. A similar chemical transformation was undertaken on an analogous dimeric compound, diospyrin, and its bioassay results were compared with those of the plumbagin derivative. Synthesis of the derivative of plumbagin did not result in a marked enhancement of the tumour‐inhibitory activity, whereas the improvement was obvious in the case of diospyrin vis à vis its hydroquinonoid analogue. The conversion of diospyrin to the hydroquinonoid compound also led to a substantial increase in the antileishmanial activity, while a similar conversion of plumbagin failed to do so. Copyright © 2002 John Wiley & Sons, Ltd.
Antiulcerogenic and analgesic effects of the Austroplenckia populnea extracts in mice
Authors: Seito L. N. , Mazaro R. , Di Stasi L. C.
Published: August 2002

Austroplenckia populnea (Reiss.) Lund. is a Brazilian Cerrado plant belonging to the Celastraceae family. Hexane and methanol extracts of leaves were investigated for their antiulcerogenic (ethanol and indomethacin/bethanecol induced gastric damage) and analgesic (writhing and tail‐flick tests) activities in mice. Acute toxic effects also were evaluated. Oral administration of both extracts at a dose of 1000 mg/kg significantly reduced the total area of the lesion, the relative area of lesion and the ulcerative index in ethanol‐induced gastric damage, but both extracts were inactive in the indomethacin/bethanecol‐induced gastric damage test. A dose dependent effect was determined with the hexane extract in the ethanol‐induced lesions test. The hexane and methanol extracts reduced the number of contortions in the writhing test, but both extracts were inactive in the tail‐flick immersion test. Copyright © 2002 John Wiley & Sons, Ltd.
A new method for the determination of cushion curves
Authors: Sek Michael A. , Minett Merv , Rouillard Vincent , Bruscella Ben
Published: August 2002

A new method for the measurement of shock‐absorbing characteristics of cushioning materials and determination of ‘cushion curves’ is discussed in this paper. The method not only significantly reduces testing time but also improves the accuracy of the estimate of a cushion curve. Cushion curves are determined from the material's static compression characteristics and the impact data (static load/peak acceleration) obtained from a small number of impacts on a cushion tester. However, the method is capable of producing a cushion curve from the measurement of just a single impact. The process involves an iterative least mean squares (ILMS) minimisation of the discrepancy between peak acceleration values predicted from a theoretical model and measured in the impact tests. The algorithm of the ILMS method, examples demonstrating its application and the dynamic effect in impacts of various materials such as the EPU, the EPS and corrugated fibreboard are presented. Copyright © 2000 John Wiley & Sons, Ltd.
Determination of ϵ‐caprolactam migration from polyamide plastics: a new approach
Authors: Pogorzelska Z. , Mielniczuk Z.
Published: August 2002

A new gas chromatography method for determination of ϵ‐caprolactam (CPR) migration from packaging materials such as: polyamide (PA) films, PA granulates, PA/PE (polyethylene) laminates, PA casings, etc., to food simulants has been developed. Water, 3% w/v acetic acid, 15% and 95% v/v ethanol and olive oil have been used as a food simulants. Using the 1,4‐butanediol (BUG) as an internal standard (instead of aza‐2‐cyclononanone), calibration curves were constructed. Very good separation of CPR from BUG was achieved by using a Nukol fused silica capillary column (Supelco), 25 m × 0.32 mm. The time of analysis is shorter than 12 min: 7.69 min for BUG and 11.60 min for CPR. The regression line equation for CPR migration to water is: y = 0.080x + 0.14; to olive oil: y = 0.010x. The sensitivity of the developed method is appropriate for the quantitative determination of CPR in an analyte concentration of approximately 0.2 mg/kg, when the specific migration limit (SML) for this compound, according to Directive 90/128/EEC, is 15 mg/kg food simulant. Copyright © 2001 John Wiley & Sons, Ltd.
Standard operating procedures for clinical research personnel – Part 10
Authors: Bohaychuk Wendy , Graham Ball CD
Published: August 2002

This is the tenth in a series of articles containing proposals for wording and content of standard operating procedures (SOPs) for clinical research activities conducted by sponsors and Contract Research Organisations (CROs). The procedures include those required by the International Conference on Harmonisation (ICH), the Food and Drug Administration (FDA), many other guidelines and regulations, and ‘best practice’ observed by the authors. The model forms require modification for actual use. In this article, SOPs are presented for various agreements and contracts which must be in place before studies begin, including protocol agreements (SOP 320), investigator responsibility agreements (SOP 321), financial agreements (SOP 322), payments to study subjects (SOP 323), confidentiality agreements (SOP 324), and insurance and indemnity agreements (SOP 325). (The full text of all 101 SOPs is available from the authors.) Copyright © 2002 John Wiley & Sons, Ltd.
What's new?
Authors: Bohaychuk Wendy
Published: August 2002

The What's New? section in the Quality Assurance Journal aims to draw attention to items of importance to QA professionals. Each item will be linked to the relevant internet address which might be added to a ‘favorites’ folder. If there is any other new information which should be brought to the attention of readers, please let us know by e‐mailing wbohaychuk@gcrpc.com Copyright © 2002 John Wiley & Sons, Ltd.
Effect of bond‐length alternation on the dipole hyperpolarizability of phenol blue
Authors: Serrano Agostinho , Canuto Sylvio
Published: August 2002

Phenol blue is a merocyanine dye that may exist in resonance between two extreme forms, a neutral keto form and a zwitterionic, charge‐separated eno form. The keto form is stable in the gas phase, while the eno form can be stabilized by solvents. In this work, the bond‐length alternation is used to monitor the change of the dipole hyperpolarizability of phenol blue continuously from the extreme eno to the other extreme keto forms. Intermediate structures were found to give the largest value for the first dipole hyperpolarizability. These values are compatible with the experimental results in different solvents and suggest that phenol blue undergoes structural changes in polar solvents. © 2002 Wiley Periodicals, Inc.; DOI 10.1002/qua.10120
Semiempirical simulation of a theta‐class glutathione S‐transferase‐catalyzed glutathione attack to the allelochemical DIMBOA
Authors: Sant'Anna Carlos Mauricio R. , De Souza Vivian Passos , Santos De Andrade Deogenes
Published: August 2002

We evaluated by the semiempirical method PM3 possible mechanisms of a putative interaction between a cereal allelochemical, the cyclic hydroxamic acid 2,4‐dihydroxy‐7‐metoxy‐2H‐1,4‐benzoxazin‐3(4H)‐one (DIMBOA), and the tripeptide glutathione (GSH) inside the active site of a theta‐class glutathione S‐transferase. Based on a preliminary study of transition states from DIMBOA reactions with methanethiolate as a simple model of GSH, we investigated the roles of catalytic residues of the enzyme during nucleophilic additions of GSH to the carbonyl groups of DIMBOA and of its phenol/aldehyde isomer inside the active site model. Our results suggest that a tyrosine residue, Tyr113, makes the most important contributions for the catalytic mechanism. In the modeled reaction steps, Tyr113 behaves as a double hydrogen bond donor catalyst for nucleophilic additions of GSH to substrates: It initially helps stabilize the strongly nucleophilic reduced GSH with a hydrogen bond intermediated by a water molecule; during substrate approach, small conformational changes enable the residue to make a direct hydrogen bond to the substrate group that develop negative charge after addition of reduced GSH. © 2002 Wiley Periodicals, Inc.; Int J Quantum Chem, 2002
E ⊗ ϵ Jahn–Teller anharmonic coupling for an octahedral system
Authors: Avram N. M. , Drăgănescu Gh. E. , Kibler M. R.
Published: August 2002

The coupling between doubly degenerate electronic states and doubly degenerate vibrations is analyzed for an octahedral system on the basis of the introduction of an anharmonic Morse potential for the vibronic part. The vibrations are described by anharmonic coherent states and their linear coupling with the electronic states is considered. The matrix elements of the vibronic interaction are built and the energy levels corresponding to the interaction Hamiltonian derived. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
A Lie group method for molecular rovibrational spectra via the broken symmetry of U(r)(2)⊗U(υ)(4)
Authors: Meng Qingtian , Yi Xizhang , Guan Daren , Ding Shiliang
Published: August 2002

A special group chain that is appropriate for describing the rovibrational spectra of linear triatomic molecules with respect to both the vibration and the rotation of molecules as harmonic oscillators is given, and the corresponding Hamiltonian is constructed. The eigenvalue expression of the Hamiltonian is similar to the formula commonly used to calculate the rovibrational spectra of linear triatomic molecules. This method eliminates the physical uncertainty brought about by a variety of group chains. The relationships between parameters in the present expression and those in the commonly used expressions are given. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 53–59, 2001
Electronic and magnetic properties of (tetrakis(2‐pyridylmethyl)‐ ethylenediamine)iron(II) perchlorate. A comparison of different computational methods
Authors: Chen Guangju , Liu Ruozhuang , Silaghi‐Dumitrescu I. , Espinosa‐Perez G. , Zentella‐Dehesa A. , Lara‐Ochoa F.
Published: August 2002

Based on the X‐ray diffraction data, electronic and magnetic properties of the (tetrakis(2‐pyridylmethyl)ethylenediamine)iron(II) perchlorate complex have been studied using three different unrestricted computational methods. The changes of energy versus temperature obtained by different computational methods are compared. The extent of spin contaminant and its influence on the energy, the spin, the charge populations, and the characteristics of molecular orbitals are analyzed in detail. Comparison of the computational results and spin‐state transition phenomena of this complex demonstrates that the B3LYP method is the most satisfactory, leading to an excellent correlation with experimental data. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 60–69, 2001
Rules on pair electron correlation in MOH (M=H, Li, Na)
Authors: Zhuo Shuping , Wei Jichong , Shen Changsheng , Ju Guanzhi
Published: August 2002

In this article, the transferable property of pair correlation energies of OH components is discussed for a series of OH containing compounds MOH (M=H, Li, Na). In this series of compounds, from OH free radicals through HOH, LiOH, NaOH to OH−, both the intra‐ and interpair correlation energies and intra‐ and intershell correlation energies of the inner orbital electrons change little. The 1s\documentclass{article}\pagestyle{empty}\begin{document}$_{\mathrm{O}}^{2}$\end{document} is very much alike in all the above OH containing systems and such a pair correlation is transferable. But the interpair correlation and intrashell correlation energies of the valence electrons are large and change a lot in all systems. In MOH molecules, the OH correlation energy contribution increases with the increase of the ionic bond strength of the compound and this contribution is always between the correlation energy values of OH free radicals and OH− atomic groups. For strong ionic compounds, we present a very simple method to estimate the correlation energy by adding the correlation energies of its component ions within the chemical accuracy (2 kcal/mol). © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 311–317, 2001
A theory of shift operators with applications to nonharmonic systems
Authors: Burrows B. L. , Cohen M. , Feldmann T.
Published: August 2002

We present a theory of shift operators (i.e., operators which shift given solutions into other solutions), including their relationship with deformed algebras and describe a general constructive method which enables us to calculate such operators for a wide class of problems. These include the classical linear differential equations of the hypergeometric and confluent hypergeometric functions, a number of soluble nonrelativistic Schrödinger equations (including one with a non‐Hermitian Hamiltonian), and a simple master equation. In general, the resulting shift‐up and shift‐down operators are level dependent but allow for the sequential generation of all required solutions. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Inner‐sphere reorganization for redox pairs M(NH3)62+/3+ (M=Mn, Fe, and Co): Models and calculations
Authors: Zhang Dongju , Liu Yongjun , Hu Haiquan , Liu Chengbu
Published: August 2002

The inner‐shell reorganization and activation models of the electron‐transfer reactions of transition‐metal hexammine complexes are presented. The inner‐shell reorganization and activation energies of several hexammine redox pairs M(NH3)62+/3+ (M=Mn, Fe, and Co) in self‐exchange reactions are studied by different formalisms. The extent of the anharmonicities in the vibration between the metal–ion and the ligands in the reorganization process of these complexes is determined. The inner‐shell barriers of these redox pairs are dependent on reorganization model used. The contribution of the individual reactants to the inner‐shell barrier is sensitive to the model used. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
A study of the molecular structure and spectroscopic properties of polycyclic polyaza‐compounds with diamond‐lattice conformations
Authors: Galasso V. , Benedetti F. , Jones D. , Modelli A.
Published: August 2002

The equilibrium structures of a selection of polycyclic polyaza‐compounds, characterized by diamond‐lattice arrangements and conformational flexibility, were investigated with the density functional method B3LYP/6‐31G(d,p). The 10‐ or 12‐membered central ring in two tricyclic tetraaza‐compounds, formally derived from tricyclo‐hexadecane and tricyclo‐octadecane, respectively, prefers a “square” geometry. The 16‐ or 24‐membered central ring in nonacyclic octaaza‐compounds, related to pentacyclo‐octacosane, and in nonacyclic dodecaaza‐ and hexadecaaza‐compounds, both related to nonacyclo‐tetratetracontane, can instead adopt two or three alternative conformations with “square” or “rectangular” geometry. The theoretical structural models are consistent with evidence from NMR and X‐ray spectroscopy. In addition, they provide a satisfactory account of the 13C NMR chemical shifts, which were predicted with a continuous set of gauge transformation calculations performed with the B3LYP/6‐311+G(2d,p) formalism. The electronic structure was also studied by means of ab initio outer valence Green function calculations, which give a consistent, overall description of the different manifolds of photoionizations, associated with the nitrogen lone pair orbitals. Electron transmission spectroscopy was employed to detect the low‐lying temporary anion states of some representative compounds. © 2001 John Wiley & Sons, Inc. Int J Quant Chem, 2001
Selective catalytic reduction of nitric oxide with ammonia: A theoretical ab initio study
Authors: Zhanpeisov Nurbosyn U. , Higashimoto Shinya , Anpo Masakazu
Published: August 2002

Ab initio quantum chemical studies at the HF/Lanl2dz level were carried out to investigate the interaction of ammonia, NO, and a mixture of the two with vanadia/titania. It was found that the replacement of Ti6c by V6c is the only feasible way to form highly dispersed vanadia over the titania. The VO species thus formed will be in octahedral symmetry with the axial distortions, and no tetrahedrally coordinated V species can be formed. Ammonia fully covers the catalyst surface either through the associative interaction with the Lewis acid site of Ti5c or the dissociative adsorption channels. The dissociation of ammonia on the O site bridging the Ti6c and V6c octahedra and on the VO group can proceed with the highest gain in energy. The formation of an adsorbed ammonium ion was found to be an energetically highly unfavorable process. The VO group is no longer expected to play a major role in the stabilization of the surface ammonium ion. NO can be activated on the Ti5c site of the catalyst containing predissociated ammonia on the bridging O site and VO group. It can be expected that the SCR reaction products are formed through the reactions of both adsorbed NO and NH2 or the desorbed NH2 group with NO in the gas phase. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Electron ionisation induced fragmentation of fused norbornene analogues containing SiMe2 or GeMe2 and oxygen bridges. Migration of SiMe2 and GeMe2 groups
Authors: Eckert‐Maksić Mirjana , Kazazić Sas̆a , Kazazić Snjez̆ana , Kirin Srećko I. , Klasinc Leo , Srzić Dunja , Z̆igon Dus̆an
Published: August 2002

The main electron ionisation induced fragmentation processes of fused norbornene analogues containing SiMe2 or GeMe2 and oxygen bridges, as well as their dependence on substitution, were investigated using mass (MS) and tandem mass (MS/MS) spectrometric analysis. Formation of the rearrangement ions of m/z 176 in the mass spectra of fused norbornene analogues containing SiMe2 and m/z 222 in the mass spectrum of norbornene analogues containing GeMe2 provides firm evidence for the migration of a SiMe2 and GeMe2 bridge, respectively. Copyright © 2001 John Wiley & Sons, Ltd.
Tandem mass spectrometric accurate mass performance of time‐of‐flight and Fourier transform ion cyclotron resonance mass spectrometry: a case study with pyridine derivatives
Authors: Hau Jörg , Stadler Richard , Jenny Titus A. , Fay Laurent B.
Published: August 2002

The interpretation of mass spectra is a key process during compound identification, and the combination of tandem mass spectrometry (MS/MS) with high‐accuracy mass measurements may deliver crucial information on the identity of a compound. Obtaining accurate mass data of fragment ions in MS/MS reveals the particular problem of mass calibration when a lockmass, which is frequently used to obtain accurate masses in MS, is absent. An alternative technique is to recalibrate the MS/MS spectrum using a reference MS/MS spectrum acquired under the same conditions. We have tested and validated this approach using a hybrid quadrupole/orthogonal acceleration reflectron‐type time‐of‐flight (TOF) mass spectrometer. The results were compared with those obtained under similar conditions on a Fourier transform ion cyclotron resonance (FT‐ICR) instrument. We found that the mass accuracy observed with such an ‘external’ recalibration on the TOF instrument in MS/MS is identical to what can be obtained on a similar instrument operating in one‐dimensional MS mode using the lockmass technique. However, mass accuracy in both cases is one order of magnitude inferior to that obtained using FTMS, and also inferior to that observed using sector field MS when operated at comparable resolution. Nevertheless, for small (<200 Da) molecules, this mass accuracy was still sufficient to have the ‘true’ elemental composition identified as the first hit in about 70% of all cases. It was possible to elucidate the fragmentation mechanism of eight azaheterocycles containing a pyridine moiety, where the accurate mass data from the TOF instrument allowed distinction between two alternative fragmentation pathways. Copyright © 2001 John Wiley & Sons, Ltd.
On‐target endoglycosidase digestion matrix‐assisted laser desorption/ionization mass spectrometry of glycopeptides
Authors: Colangelo Jennifer , Orlando Ron
Published: August 2002

The digestion of glycopeptides with endoglycosidases can be used in the process of their structural characterization, and matrix‐assisted laser desorption/ionization‐mass spectrometry (MALDI‐MS) is often used to analyze the products of these digestions. In the currently accepted protocol for the endoglycosidase digestion of glycopeptides on the MALDI target, the target must be incubated at 37 °C, and an hour or more is needed for digestion. We have modified the procedure so that the process can be performed at room temperature in 5 to 15 min, and digestions are performed in the presence of a MALDI matrix. The endoglycosidases used for digestion were endoglycosidase H and peptide‐N‐glycosidase F. Glycopeptides from asialofetuin and endopolygalacturonase (EPG) II were used as standards because their glycan structures have been previously characterized. Glycopeptides with unknown glycan structures were also digested, including glycopeptides from pectate lyase, EPG I, and pectin methylesterase from Aspergillus niger. Copyright © 2001 John Wiley & Sons, Ltd.
Comparative analysis of glycosylinositol phosphorylceramides from fungi by electrospray tandem mass spectrometry with low‐energy collision‐induced dissociation of Li+ adduct ions
Authors: Levery Steven B. , Toledo Marcos S. , Straus Anita H. , Takahashi Helio K.
Published: August 2002

Glycosylinositol phosphorylceramides (GIPCs) are a class of acidic glycosphingolipids (GSLs) expressed by fungi, plants, and certain parasitic organisms, but not found in cells or tissues of mammals or other higher animals. Recent characterizations of fungal GIPCs point to an emerging diversity which could rival that already known for mammalian GSLs, and which can be expected to present a multitude of challenges for the analytical chemist. Previously, the use of Li+ cationization, in conjunction with electrospray ionization mass spectrometry (ESI‐MS) and low‐energy collision‐induced dissociation tandem mass spectrometry (ESI‐MS/CID‐MS), was found to be particularly effective for detailed structural analysis of monohexosylceramides (cerebrosides) from a variety of sources, including fungi, especially minor components present in mixtures at extremely low abundance. In applying Li+ cationization to characterization of GIPCs, a substantial increase in both sensitivity and fragmentation was observed on collision‐induced dissociation of [M + Li]+ versus [M + Na]+ for the same components analyzed under similar conditions, similar to results obtained previously with cerebrosides. Molecular adduct fragmentation patterns were found to be systematic and characteristic for both the glycosylinositol and ceramide moieties with or without phosphate. Interestingly, significant differences were observed in fragmentation patterns when comparing GIPCs having Manα1 → 2 versus Manα1 → 6Ins core linkages. In addition, it was useful to perform tandem product ion scans on primary fragments generated in the orifice region, equivalent to ESI‐(CID‐MS)2 mode. Finally, precursor ion scanning from appropriate glycosylinositol phosphate product ions yielded clean molecular ion profiles in the presence of obscuring impurity peaks. The methods were applied to detailed characterization of GIPC fractions of increasing structural complexity from a variety of fungi, including a non‐pathogenic Basidiomycete (mushroom), Agaricus blazei, and pathogenic Euascomycete species such as Aspergillus fumigatus, Histoplasma capsulatum, and Sporothrix schenckii. The analysis confirmed a remarkable diversity of GIPC structures synthesized by the dimorphic S. schenckii, as well as differential expression of both glycosylinositol and ceramide structures in the mycelium and yeast forms of this mycopathogen. Mass spectrometry also established that the ceramides of some A. fumigatus GIPC fractions contain very little 2‐hydroxylation of the long‐chain fatty‐N‐acyl moiety, a feature that is not generally observed with fungal GIPCs. Copyright © 2001 John Wiley & Sons, Ltd.
Characterization of low molecular weight hydrocarbon oligomers by laser desorption/ionization time‐of‐flight mass spectrometry using a solvent‐free sample preparation method
Authors: Pruns Julia K. , Vietzke Jens‐Peter , Strassner Manfred , Rapp Claudius , Hintze Ulrich , König Wilfried. A.
Published: August 2002

A new solvent‐free sample preparation method using silver trifluoroacetate (AgTFA) was developed for the analysis of low molecular weight paraffins and microcrystalline waxes by laser desorption/ionization time‐of‐flight mass spectrometry (LDI‐TOFMS). Experiments show that spectral quality can be enhanced by dispersing AgTFA directly in liquid paraffins without the use of additional solvents. This preparation mixture is applied directly to the MALDI probe. Solid waxes could be examined by melting prior to analysis. The method also provides sufficiently reproducible spectra that peak area ratios between mono‐ and bicyclic alkane peaks indicated variations in the cycloalkane content of paraffin samples. Dehydrogenation of hydrocarbons observed during the desorption/ionization process was studied by analysis of alkane standards. Copyright © 2002 John Wiley & Sons, Ltd.
Getting There from Here: New Environmental Insurance Policies Can Make Deals Work
Authors: Smith Diane R.
Published: August 2002

This article illustrates the way environmental insurance policies can be used, and discusses some of the
major considerations that must or should be taken into account when making a decision both as to coverage and as
to the structure of a transaction. Diane Smith has been practicing environmental law for over 25 years. In this
article, she discusses using the new environmental insurance policies to facilitate deals. The issues raised
have come up in one or more recent transactions that have utilized the new policy forms to make otherwise
difficult or impossible transactions work. © 2001 John Wiley & Sons
A Practical Guide to Estimating Cleanup Costs
Authors: Goldstein Mike L. , Ritterling Jon M.
Published: August 2002

Cost estimates are frequently developed to evaluate hazardous‐waste‐site cleanup options in
support of a site investigation, remedy selection decision, or assessment of environmental liabilities. The
accuracy of the cost estimate depends largely on the quality of the information available at the time it is
prepared. This article presents a practical guide to developing a cleanup cost estimate. It includes information
on how to document assumptions, use the latest technical resources, and perform basic adjustments to account for
uncertainty and the time value of money. The content is based upon a recent guidance document issued by the U.S.
Environmental Protection Agency and U.S. Army Corps of Engineers entitled A Guide to Developing and
Documenting Cost Estimates during the Feasibility Study (USEPA, 2000). © 2001 John Wiley
& Sons, Inc.
A note on a theorem of Rantzer
Authors: Dzhafarov V. , Koçak Ş. , Azcan H.
Published: August 2002

In this note we fill the missing cases of a theorem of Rantzer on the relationship between n‐convex directions and the growth condition. We mainly show that if a second or a third order polynomial is a 3‐convex direction, then it satisfies the growth condition. Copyright © 2002 John Wiley & Sons, Ltd.
Size and path length of Patricia tries: Dynamical sources context
Authors: Bourdon Jérémie
Published: August 2002

Digital trees, such as tries, and Patricia tries are data structures routinely used in a variety of computer and communication applications including dynamic hashing, partial match retrieval, searching and sorting, conflict resolution algorithms for communication broadcast, data compression, and so forth. Here, we consider tries and Patricia tries built from n words emitted by a probabilistic dynamical source. Such sources encompass classical and many models such as memoryless sources and finite Markov chains. The probabilistic behavior of its main parameters, namely, the size and the path length, appears to be determined by some intrinsic characteristics of the source, such as Shannon entropy and entropy‐like constants, that depend on the spectral properties of specific transfer operators of Ruelle type. © 2001 John Wiley & Sons, Inc. Random Struct. Alg., 19: 289–315, 2001
Parking with density
Authors: Marckert Jean‐François
Published: August 2002

We study parkings with n places, where m(n) cars are placed according to a nonuniform probability. The aim of this paper is to show a threshold function (depending on the distribution) for the emergence of a giant component. The size of the largest blocks of consecutive occupied places and the total displacement of the cars are also studied. ©2001 John Wiley & Sons, Inc. Random Struct. Alg., 18: 364–380, 2001.