bluuebunny/crossref_metadata_2025 huggingface dataset:
Polyrotaxanes by free‐radical polymerization of acrylate and methacrylate monomers in the presence of a crown ether
Authors: Gibson Harry W. , Bryant William S. , Lee Sang‐Hun
Published: August 2002

Poly[(methyl acrylate)‐rotaxa‐(30‐crown‐10)] (5) and poly[(methyl methacrylate)‐rotaxa‐(30‐crown‐10)] (6) were synthesized by azobisisobutyronitrile‐initiated free‐radical bulk polymerizations of the respective monomers in the presence of 30‐crown‐10 (1; equimolar; 5 times the monomer mass). For 5, 3.8 mass % (0.81 mol % with respect to the monomer) of the crown was incorporated versus 1.7 mass % (0.39 mol % with respect to the monomer) for 6. Control reactions with 18‐crown‐6, which is to small to be threaded, showed that chain transfer to the crown ethers was detectable only for the acrylate but was relatively negligible and spectroscopically distinct. The threading yields were much higher with these systems than with polystyrene, most likely because of the greater compatibility of the crown ether with these polar monomers and polymers and the consequent ability to carry out the polymerizations homogeneously in the absence of added solvent; however, the threading process was still essentially statistical. Therefore, the polymerization of methacrylate monomers 8a–8c based on tetraarylmethane moieties connected via diethyleneoxy or triethyleneoxy spacers was examined in the presence of 1 in the belief that the supramolecular semirotaxane monomer 9 formed statistically in situ could be captured more efficiently and produce higher threading yields, presumably of side‐chain polyrotaxanes, than the simple (meth)acrylate monomers. Azobisisobutyronitrile‐initiated polymerizations either neat or in toluene produced polyrotaxanes 10 with up to about 1.6 mass % and 2 mol % threaded crown ether, presumably trapped on the pendant stoppered side chains. Although primarily statistical in nature, the latter rotaxane syntheses afforded on a molar basis 3–7 times more efficient incorporation of 1 than styrene (0.33 mol %), methyl acrylate (0.81 mol %), or methyl methacrylate (0.39 mol %) monomers for the preparation of main‐chain polypseudorotaxanes and indeed even surpassed the 60‐crown‐20/polyacrylonitrile system (1.5 mol %). This was presumed to be due to the fact that the loss of the crown ether, once it was threaded onto the monomer to form 9 and the latter was polymerized, was either retarded (by the tetraphenylmethyl stopper in 10a) or prevented completely [by tris(p‐t‐butylphenyl)phenylmethyl stoppers in 10b and 10c]. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1978–1993, 2001
Copolymerization behavior of direct polycondensation of AB2 and AB monomers that forms hyperbranched aromatic polyamide copolymers
Authors: Jikei Mitsutoshi , Fujii Ken , Kakimoto Masa‐Aki
Published: August 2002

The copolymerization behavior of the one‐step direct polycondensation of 3,5‐bis‐(4‐aminophenoxy)benzoic acid (AB2 monomer) and 3‐(4‐aminophenoxy)benzoic acid (AB monomer) was investigated by IR and 13C NMR measurements. IR measurements revealed that the content of the AB2 units in the polymer was higher in the early stages of polymerization. 13C NMR spectra of the polymers indicated that the number of dendritic units increased slowly with increasing reaction time. The stepwise copolymerization of the AB2 and AB monomers was also carried out, and the structure was analyzed by 13C NMR measurements. Copolymer synthesized stepwise by adding AB2 monomer first (polymer II) had more dendritic units and less terminal units as compared with the one‐step copolymer (polymer I). Copolymer synthesized stepwise by adding AB monomer first gave a resulting copolymer (polymer III) composed of long AB chains. The solubility of the stepwise copolymers was low, and the inherent viscosity was high in comparison with the one‐step copolymer as a result of the difference in architecture of the copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3304–3310, 2001
Reversible melting in nanophase‐separated poly(oligoamide‐alt‐oligoether)s and its dependence on sequence length, crystal perfection, and molecular mobility
Authors: Di Lorenzo Maria Laura , Pyda Marek , Wunderlich Bernhard
Published: August 2002

The degree of reversibility of the melting of multiblock copolymers of alternating oligoamides and oligoethers was investigated with respect to the composition and molecular mass of the blocks. The analysis was conducted with temperature‐modulated calorimetry, and it revealed different degrees of reversibility of the melting process that depended on the block length, crystal perfection, and molecular mobility. For the oligoamide blocks, the amount of crystal that melts and crystallizes reversibly during quasi‐isothermal analysis increases with decreasing molar mass, and shorter amide sequences form poorer crystals that have a higher tendency toward reorganization. Reorganization of the oligoamides is also favored by the presence of the more mobile oligoether units. Reversible melting of the oligoether segments is influenced by the presence of glassy and crystalline oligoamide blocks in the adjacent nanophases. Because of the segmented nature of the copolymers, the oligoether segments are not free to flow as in an isotropic melt but are anchored to the oligoamide surfaces with different degrees of restriction that change the local equilibrium of melting and recrystallization. A comparison of the copolymers with the corresponding homopolymers provides information about the role of molecular nucleation and mobility in the reversibility of melting. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2969–2981, 2001
Energy storage and strain‐recovery processes in highly deformed semicrystalline poly(butylene terephthalate)
Authors: Ricco T. , Pegoretti A.
Published: August 2002

Nonelastic deformation of semicrystalline poly(butylene terephtalate) (PBT) was investigated by calorimetric measurements and strain‐recovery tests. Differential scanning calorimetry on PBT specimens deformed both below and above their glass‐transition temperature (Tg ≈ 50 °C) showed the presence of a broad exothermal peak whose area represents the energy released for the nonelastic strain recovery. This energy became more and more pronounced as the strain level increased, and it decreased as the deformation temperature increased, even if a significant contribution was detected on specimens deformed at temperatures much higher than Tg. For two temperature conditions (21 and 100 °C), strain‐recovery master curves were built showing the following two distinct deformation components: one recoverable with time and another one irreversible, this latter one arising from relatively low levels of strain. The recoverable component can be erased by heating the material at temperatures much higher than its Tg, close to the onset of the melting process. On the other hand, the irreversible strain component does not recover even if the material is brought close to the onset of the crystals melting. The shift factor for the strain‐recovery master curves was compared with the shift factor for the construction of the dynamic storage modulus master curve obtained in the linear viscoelastic regime (small strain). © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 236–243, 2002
Morphology of ABC triblock copolymer/homopolymer blend systems
Authors: Suzuki Jiro , Furuya Motofumi , Iinuma Minobu , Takano Atsushi , Matsushita Yushu
Published: August 2002

Morphological variations of ABC triblock copolymers through the blending of B or A/C homopolymers, all with short chain lengths, were studied experimentally. The samples were symmetric ISP triblock copolymers, where I, S, and P denote polyisoprene, polystyrene, and poly(2‐vinylpyridine), and component homopolymers. Microphase‐separated structures of the solvent‐cast films were observed with transmission electron microscopy and small‐angle X‐ray scattering. For an ISP/S system, the lattice constant of the tricontinuous gyroid structure (G‐structure) increased with an increase in the volume fraction of S (ϕs) if the amount of added homopolymer was small, but it reached a certain limit, reflecting the fact that the midblock chain had a limit for chain stretching. For I/ISP/P blends, on the contrary, the lattice constant of the G‐structure continued increasing with decreasing ϕs. This result shows that the I and P domains did not have a limit for chain stretching because the two end blocks had free ends. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1135–1141, 2002
Discrepancies between attainment and importance of life values and anxiety and depression in gastrointestinal cancer patients and their spouses
Authors: Nordin Karin , Wasteson Elisabet , Hoffman Katarina , Glimelius Bengt , Sjödén Per‐Olow
Published: August 2002

Patients' satisfaction with life, viewed in terms of the discrepancy between the perceived attainment and subjective importance of various life values, is a less often studied phenomenon for understanding the psychological adaptation in cancer patients. The main aim of the present study is to investigate the relation between the degree of attainment and importance of life values on the one hand, and anxiety and depression, on the other. A consecutive series of 85 newly diagnosed patients with gastrointestinal (GI) cancers, 52 potentially cured and 33 with an advanced disease, and 26 spouses to the patients with an advanced disease participated. The patients and spouses of non‐cured patients filled out questionnaires twice, close to the diagnosis and after 1 (non‐cured patients) or 3 months. Overall, large discrepancies between the perceived attainment and importance of life values were associated with high anxiety and depression. For the patients (both cured and non‐cured), the discrepancies decreased for several life values over time, as did anxiety and depression. For the spouses of the non‐cured patients, there was no decrease either for life value discrepancies or for anxiety/depression. This suggests that patients, in contrast to their spouses, strive to achieve small discrepancies between the perceived attainment and importance of life values, as part of their adjustment to serious diseases, e.g. cancer. Copyright © 2001 John Wiley & Sons, Ltd.
Modelling the distribution of palsas in Finnish Lapland with logistic regression and GIS
Authors: Luoto Miska , Seppälä Matti
Published: August 2002

The location of palsas (peat mounds with a perennially frozen core) was mapped in an area of 3370 km2 in Finnish Lapland by interpreting aerial digital photographs. Using environmental variables derived from digital land cover data and an elevation model, the distribution of palsas was modelled using geographic information system (GIS) techniques and multiple logistic regression. The relative roles of eight environmental variables potentially affecting the distribution of the palsas were studied in a spatial grid system with 3370 grid squares of 1.0 km2, of which 172 were found to contain palsas. The altitudes of the palsas varied from 180 m to 390 m. In the logistic regression model the probability of the presence of a palsa in a 1.0 km2 square increased with 1) the area of mire, 2) the proportion of flat topography, 3) water cover and 4) elevation of the lowest point in the 1.0 km2 analysis square. The palsa distribution model was validated by fitting it to an independent test area of 300 squares bordering on the main study area: the overall classification rate was 97.67%. The application of GIS data and techniques with logistic regression modelling has potential for wide use in studies on distribution patterns in periglacial processes and landforms. Copyright © 2002 John Wiley & Sons, Ltd.
Defining an exacerbation of pulmonary disease in cystic fibrosis*
Authors: Dakin Carolyn , Henry R.L. , Field P. , Morton J.
Published: August 2002

Despite the importance of pulmonary exacerbations in CF in both clinical and research settings, both published evidence and consensus are lacking concerning the criteria used to define an exacerbation. The use of hospitalization as a surrogate measure presupposes uniformity among clinicians in diagnosis and treatment of exacerbations. Our aims were to evaluate consensus among clinicians about the variables considered helpful in diagnosing an exacerbation requiring treatment. A comprehensive list of symptoms, signs, and investigations used to define exacerbations was compiled from published trials. A written self‐administered questionnaire included the list in age‐appropriate groups to survey opinion about the helpfulness of each item, and the estimated proportion of patients admitted within a month of diagnosis of an exacerbation. This was sent to all clinicians managing CF patients in Australia.

There were replies from 59/91 clinicians (65%), 41/60 (68%) from those managing children and 18/31 (58%) from those managing adults. Responses of those managing children and adults differed for 7/32 variables (Mann‐Whitney test, P < 0.05). Clinic grouping did not show greater consensus among responses of pediatricians (Kruskal‐Wallis test, P = 0.362). Consensus, >74% or <26% of respondents rating a variable helpful/very helpful, was found in only 50% of variables listed. Estimated admission rate within a month of diagnosis was 61% (30–100%) for those managing adults and 48% %5–100%) for pediatricians.

A lack of consensus was found among clinicians managing CF about the variables considered in diagnosing an exacerbation. The estimated proportion admitted within a month of diagnosis was very variable. This demonstrated inhomogeneity in approach to diagnosis and management of an exacerbation suggests a significant heterogeneity of clinical care. Pediatr Pulmonol. 2001; 31:436–442. © 2001 Wiley‐Liss, Inc.
Increased fatty acid synthase as a therapeutic target in androgen‐independent prostate cancer progression
Authors: Pizer Ellen S. , Pflug Beth R. , Bova G. Steven , Han Wan Fang , Udan Michael S. , Nelson Joel B.
Published: August 2002

BACKGROUND

Fatty acid synthase (FAS) performs the anabolic conversion of dietary carbohydrate or protein to fat. FAS expression is low in most normal tissues, but is elevated in many human cancers, including androgen‐sensitive and androgen‐independent prostate cancer.

METHODS

Immunohistochemical evaluation of FAS expression was performed in human prostate cancer specimens under various states of androgen ablation. In vitro and in vivo prostate cancer models were evaluated for FAS expression and activity under androgenic and androgen‐depleted conditions, and were tested for sensitivity to antimetabolite drugs that target fatty acid synthesis.

RESULTS

While FAS expression in the prostate was androgen responsive, it persisted or was reactivated in human prostate carcinoma after androgen ablation, and was high in 82% of lethal tumors examined at autopsy. Similar patterns of FAS expression and fatty acid synthesis were seen in cell culture and xenograft models of human prostate cancer. Pharmacologic inhibition of FAS resulted in a dose‐dependent reduction of tumor growth in these models, including fourfold inhibition of an androgen‐independent human prostate cancer xenograft with little associated toxicity.

CONCLUSIONS

The data suggest that FAS expression/FA synthesis provides an important functional aspect of the malignant phenotype in prostate cancer, perhaps supporting cell growth or survival. FAS expression may be upregulated by alternate signaling pathways important for prostate cancer growth under androgen withdrawal. The re‐emergence of FAS expression and activity during the development of androgen independence demonstrate that FAS may serve as a novel target for antimetabolite therapy in prostate cancer. Prostate 47:102–110, 2001. © 2001 Wiley‐Liss, Inc.
Altered expression of extracellular matrix and proteinases in noble rat prostate gland after long‐term treatment with sex steroids
Authors: Li S.C. , Chen G.F. , Chan Peter S.F. , Choi H.L. , Ho Shuk‐Mei , Chan Franky L.
Published: August 2002

BACKGROUND

Interactions between the epithelial cells and stromal tissues, which include the epithelial basement membrane, extracellular matrix, inducible factors, and various cell types, are believed to play a significant role in prostate gland carcinogenesis. Remodeling of extracellular matrix and degradation of basement membrane are the prerequisites for tumor cell invasion, and these changes are correlated with the expression of various proteinases.

METHODS

The present study examined the alterations of epithelial basement membrane, extracellular matrix, and proteinase activities in the Noble rat prostate gland after long‐term treatments with androgen and estrogen (T+DES or T+E2 for 4–12 months) by histochemistry, immunohistochemistry, electron microscopy, and gelatin‐gel zymography.

RESULTS

After hormonal treatments, defects of epithelial basement membranes, such as focal disruption, diffuse staining and multilayering, were observed by histochemistry and immunohistochemistry in the dysplastic and neoplastic lesions induced in the lateral (LP) and ventral prostates (VP) but not in dorsal prostate (DP). An increase in the amount of extracellular matrix components, including hyaluronan (HA), chondroitin sulfate proteoglycan (CSPG) and tenascin, in the stroma of hormone‐treated LP and VP was revealed by histochemistry and immunohistochemistry. Positive immunolabeling of matrix metalloproteinases 2 (MMP‐2) and 9 (MMP‐9) was detected in the fibromuscular layer surrounding the adenoma and adenocarcinoma induced in LP and VP after treatments with steroids for over 9–12 months. Zymography also detected an increase in activities of proteinases of apparent MW 120, 90, 86 and 68 kDa in the hormone‐treated LP and VP, and these proteinases were characterized as metalloproteinases. In addition, two serine proteinases of MW 100 and 30 kDa were identified as being overexpressed in the hormone‐treated LP and VP. Compared to LP and VP, there was no significant change in the proteinase activities in the hormone‐treated DP.

CONCLUSIONS

The present study demonstrated that the epithelial basement membrane and stromal extracellular matrix were altered in dysplastic and neoplastic Noble rat prostates. Since HA and CSPG (or their complexes) are highly anionic molecules, their increased accumulation in the altered prostatic stroma would tend to hydrate this tissue. This would create an environment more favorable for tumor growth and invasion. These morphological changes were also correlated with the concurrent increase in gelatinolytic proteinase activities induced in these prostates. The results suggest that the remodeling of the stromal tissue might play a role in the early stage of prostate carcinogenesis as shown in the Noble rat model. Prostate 49:58–71, 2001. © 2001 Wiley‐Liss, Inc.
Denatured collapsed states in protein folding: Example of apomyoglobin
Authors: Tcherkasskaya Olga , Uversky Vladimir N.
Published: August 2002

Experimental approaches, including circular dichroism, small angle X‐ray scattering, steady‐state fluorescence, and fluorescence energy transfer, were applied to study the 3D‐structure of apomyolgobin in different conformational states. These included the native and molten globules, along with either less ordered conformations induced by the addition of anions or completely unfolded states. The results show that the partially folded forms of apomyoglobin stabilized by KCl and/or Na2SO4 under unfolding conditions (pH 2) exhibit a significant amount of secondary structure (circular dichroism), low packing density of protein molecules (SAXS), and native‐like dimensions of the AGH core (fluorescence energy transfer). This finding indicates that a native‐like tertiary fold of the polypeptide chain, i.e., the spatial organization of secondary structure elements, most likely emerges prior to the formation of the molten globule state. Proteins 2001;44:244–254. © 2001 Wiley‐Liss, Inc.
Interaction of dinotefuran and its analogues with nicotinic acetylcholine receptors of cockroach nerve cords
Authors: Mori Kazuki , Okumoto Takashi , Kawahara Nobuyuki , Ozoe Yoshihisa
Published: August 2002

To investigate the action of dinotefuran (MTI‐446, 1‐methyl‐2‐nitro‐3‐(tetrahydro‐3‐furylmethyl)guanidine), a recently developed insecticide, on insect nicotinic acetylcholine receptors (nAChRs), we determined the potencies of the compound and 15 analogues in inhibiting the specific binding of [3H]epibatidine (EPI), a nAChR agonist, and [3H]α‐bungarotoxin (α‐BGT), a competitive nAChR antagonist, to the nerve cord membranes of American cockroaches (Periplaneta americana). Racemic dinotefuran inhibited [3H]EPI binding with an IC50 of 890 nM and [3H]α‐BGT binding with an IC50 of 36.1 µM. Scatchard analysis indicated that the dinotefuran inhibition of [3H]EPI binding was a competitive one. Slight structural modification caused a drastic reduction in potency; only four analogues were found to be equipotent to or more potent than dinotefuran. Chloropyridinyl and chlorothiazolyl neonicotinoid insecticides displayed two or three orders of magnitude higher potency than dinotefuran. There was a good correlation between the IC50 values of tested compounds obtained with [3H]EPI and those obtained with [3H]α‐BGT. A better correlation was observed between 3‐h knockdown activities (KD50) against German cockroaches (Blattella germanica) and IC50 values obtained from [3H]EPI assays than between 24‐h lethal activities (LD50) and IC50 values. While the results indicate that dinotefuran and its analogues interact with the ACh‐binding site in cockroach nAChRs, it remains to be elucidated why they displayed lower potencies than those expected based on their insecticidal activities.

© 2001 Society of Chemical Industry
Using observed load distributions with a simple model to analyse the epidemiology of sea lice (Lepeophtheirus salmonis) on sea trout (Salmo trutta)
Authors: Murray Alexander G
Published: August 2002

Sea lice are ectoparasites of salmonids that have been associated with the recent decline in sea trout numbers in north‐west Europe. Observed patterns of louse load distribution between sea trout in the seas surrounding the UK, Ireland and Norway and a simple model have been used to analyse the epidemiology of lice. Loads are aggregated and deviate strongly from the Poisson distribution, although less than is observed with many other parasites. The louse numbers on fish from offshore sites are slightly less variable than for fish from coastal sites with comparable mean loads. Analysis of louse development stages and sexes shows that selection between hosts by sea lice plays a limited role. If host selection is absent, then associated poor condition would be caused by, not the cause of, high louse burdens; however the absence of such selection is not proved. Scenarios with infection that is patchy in space and time best generate the aggregated load patterns observed; these patches accord with observed swarms of copepodids. Prevalence patterns may indicate the movement of trout between environments. Control of copepodids in infection ‘hot spots’, either directly or through control of louse egg production in their catchment, may reduce louse loads on wild sea trout and, in particular, extreme and damaging loads.

© 2002 Society of Chemical Industry
Synthesis and Application of Fmoc‐His(3‐Bum)‐OH
Authors: Mergler M. , Dick F. , Sax B. , Schwindling J. , Vorherr Th.
Published: August 2002

This paper presents a reevaluation of the synthesis and properties of Fmoc‐His(3‐Bum)‐OH regarding its application in SPPS with minimal racemization of histidine residues during coupling and esterification reactions. By‐product formation during the deprotection of the test peptides could be significantly reduced by scavenging the concomitantly formed HCHO, e.g. with methoxyamine. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
Fibre‐reinforced polymers in reinforced and prestressed concrete applications: moving forward
Authors: Lees J M
Published: August 2002

Recent developments in the use of fibre‐reinforced polymers (FRPs) in reinforced and prestressed concrete applications are reviewed. The influence of FRP material properties on the design of concrete structures is considered and applications are discussed in conjunction with the structural function of the FRP reinforcement. The review includes examples of the practical implementation of the technology and addresses important durability issues. A number of future considerations/research needs are identified and the requirement for the provision of standard, sustainable and cost‐effective FRP solutions is highlighted. It is concluded that although there have been significant advances in our knowledge of the behaviour of FRP‐concrete structures, the timeframe in which FRPs will no longer be considered as new materials remains ambiguous.
An overview of reinforced concrete core wall–steel frame hybrid structures
Authors: Shahrooz Bahram M , Gong Bingnian , Tunc Gokhan , Deason Jeremy T
Published: August 2002

An overview of a number of issues related to design of hybrid structures with reinforced concrete central core walls and perimeter steel frames is presented. Various design options for steel or steel–concrete composite coupling beams and their connections to core walls, and connections between outrigger beams and core walls are discussed. Design guidelines are presented and are evaluated with reference to previous experimental data from tests conducted by the authors. By following the recommended design procedures, it is possible to ensure satisfactory cyclic behaviour in terms of strength and energy dissipation characteristics.
Vibration serviceability of timber floors in residential construction
Authors: Hu Lin J , Chui Ying H , Onysko Donald M
Published: August 2002

The main focus of this review is the chronological development of design approaches to minimize excessive vibrations in residential timber floors. To aid readers in understanding the fundamental issues, factors affecting human response to floor vibrations are discussed. Discussion also covers the link between these factors and floor construction details. The final section of the review discusses unresolved codification issues. A general conclusion is that, while each of the design approaches reviewed has achieved certain degree of success, none appears to be robust enough to cover the full range of construction details and materials currently being used by the building industry.
Fracture toughness requirements for highway bridges: past and future trends
Authors: Wright W J
Published: August 2002

Fracture toughness requirements were implemented for bridge steels during the early 1970s. The philosophy behind these requirements was to provide sufficient material toughness to prevent lower‐shelf, brittle fracture at service temperatures and load rates experienced by bridges. These requirements do not alone prevent fracture, and designers must also consider proper fatigue design, fabrication quality control, and routine in‐service inspection to insure structural safety. This fracture control plan has been effective in preventing brittle fracture in most cases, but when any aspect of the plan is not performed correctly, fracture failure still can occur in bridges.

There have been significant advances in steel making practice since the 1970s, and new grades of high performance steel (HPS) are available with vastly superior toughness compared to conventional steels. Work is underway at the Federal Highway Administration to characterize the fracture performance of these new steels using test methods that quantify ductile fracture resistance. The goal is to develop an improved fracture control plan that essentially eliminates brittle fracture as a limit state for bridges. Ultimately, this level of performance will enable designers to consider less structurally redundant design concepts, resulting in more economical structures.
Antimicrobial activity of Streblus asper leaf extract
Authors: Wongkham Sopit , Laupattarakasaem Pisamai , Pienthaweechai Keskaew , Areejitranusorn Premjai , Wongkham Chaisiri , Techanitiswad Tipawan
Published: August 2002

Bactericidal activity was found in the 50% ethanol (v/v) extract of Streblus asper leaves. The extract possessed a selective bactericidal activity towards Streptococcus, especially to Streptococcus mutans which has been shown to be strongly associated with dental caries. The extract had no effect on cultures of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, Staphylococcus coagulase positive, Staphylococcus coagulase negative, Serratia marcescens, Klebsiella pneumoniae, Enterobacter, Pseudomonas aeruginosa, Burkholderia pseudomeallei and Candida albicans. The minimum growth inhibitory concentration and the minimum bactericidal concentration of S. asper extract against 108 CFU/mL of S. mutans was 2 mg/mL. The active compound is partially polar, partially heat labile, precipitated by 80% ammonium sulphate, and possesses a molecular weight larger than 10 000 Da. The potential for using S. asper extract as a natural product for controlling dental caries is discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Antimicrobial activity of some Pacific Northwest woods against anaerobic bacteria and yeast
Authors: Johnston W. H. , Karchesy J. J. , Constantine G. H. , Craig A. M.
Published: August 2002

Extracts of woods commonly used for animal bedding were tested for antimicrobial activity. Essential oils from Alaska cedar (Chamaecyparis nootkatensis), western juniper (Juniperus occidentalis) and old growth Douglas fir (Pseudotsuga menziesii) as well as methanol extracts of wood from these trees plus western red cedar (Thuja plicata) and ponderosa pine (Pinus ponderosa) were tested for antimicrobial activity against anaerobic bacteria and yeast. The test microbes included Fusobacterium necrophorum, Clostridium perfringens, Actinomyces bovis and Candida albicans which are common to foot diseases and other infections in animals. The essential oils and methanol extracts were tested using a standardized broth assay. Only extracts of Alaska cedar and western juniper showed significant antimicrobial activity against each of the microbes tested. The essential oil of Douglas fir did show antimicrobial activity against A. bovis at the concentrations tested. The methanol extracts of the heartwood of Douglas fir and the sapwood of ponderosa pine showed no antimicrobial activity. The major chemical components of western juniper (cedrol and α‐ and β‐cedrene) and Alaska cedar (nootkatin) were also tested. In western juniper, α‐ and β‐cedrene were found to be active components. Nootkatin showed activity only against C. albicans. The inhibitory activity in Alaska cedar oil was high enough to justify further efforts to define the other chemical components responsible for the antimicrobial activity. Copyright © 2001 John Wiley & Sons, Ltd.
Antiviral activities of extracts isolated from Terminalis chebula retz., Sanguisorba officinalis L., Rubus coreanus miq. and Rheum palmatum L. against hepatitis B virus
Authors: Kim Tae Gyun , Kang Seog Youn , Jung Ki Kyung , Kang Ju Hye , Lee Euna , Han Hyung Mee , Kim Seung Hee
Published: August 2002

The antiviral effects of aqueous extracts of Terminalis chebula Retz., Sanguisorba officinalis L., Rubus coreanus Miq. and Rheum palmatum L. were examined by a cell culture system using a hepatitis B virus (HBV) producing cell line, HepG2 2.2.15. The extracts were assayed for the inhibition of HBV multiplication by measurement of HBV DNA and surface antigen (HBsAg) levels in the extracellular medium of HepG2 2.2.15 cells after an 8‐day treatment. All extracts decreased the levels of extracellular HBV virion DNA at concentrations ranging from 64 to 128 μg/mL and inhibited the secretion of HBsAg dose dependently. Of the four tested plants, Terminalis chebula exhibited the most prominent anti‐HBV activities. Copyright © 2001 John Wiley & Sons, Ltd.
Promising hypotensive effect of hawthorn extract: A randomized double‐blind pilot study of mild, essential hypertension
Authors: Walker Ann F. , Marakis Georgios , Morris Andrew P. , Robinson Paul A.
Published: August 2002

This pilot study was aimed at investigating the hypotensive potential of hawthorn extract and magnesium dietary supplements individually and in combination, compared with a placebo. Thirty‐six mildly hypertensive subjects completed the study. At baseline, anthropometric and dietary assessment, as well as blood pressure measurements were taken at rest, after exercise and after a computer ‘stress’ test. Volunteers were then randomly assigned to a daily supplement for 10 weeks of either: (a) 600 mg Mg, (b) 500 mg hawthorn extract, (c) a combination of (a) and (b), (d) placebo. Measurements were repeated at 5 and 10 weeks of intervention. There was a decline in both systolic and diastolic blood pressure in all treatment groups, including placebo, but ANOVA provided no evidence of difference between treatments. However, factorial contrast analysis in ANOVA showed a promising reduction (p = 0.081) in the resting diastolic blood pressure at week 10 in the 19 subjects who were assigned to the hawthorn extract, compared with the other groups. Furthermore, a trend towards a reduction in anxiety (p = 0.094) was also observed in those taking hawthorn compared with the other groups. These findings warrant further study, particularly in view of the low dose of hawthorn extract used. Copyright © 2002 John Wiley & Sons, Ltd.
Reliability evaluation for linear consecutively‐connected systems with multistate elements and retransmission delays
Authors: Levitin Gregory
Published: August 2002

A linear consecutively‐connected system consists of N linear ordered positions at which statistically‐independent multistate elements with different characteristics are allocated. Each element can provide propagation of a signal it receives from the previous positions to the next few positions. Each element can have different states determined by a number of adjacent nodes receiving the signal directly from this element. The signal retransmission process is associated with delays. The system fails if the signal generated at the first position (source) cannot reach the Nth position (receiver) within a specified time. An algorithm based on the universal generating function method is presented in this paper for determination of reliability of the linear consecutively‐connected system with delays. Copyright © 2001 John Wiley & Sons, Ltd.
Weighted least‐squares estimation of the shape parameter of the Weibull distribution
Authors: Hung Wen‐Liang
Published: August 2002

The purpose of this paper is to propose the weighted least‐squares procedure for estimating the shape parameter of the Weibull distribution. Results from simulation studies illustrate the mean‐squared error of the weighted least‐squares estimator is smaller than competing procedures in all cases considered. Copyright © 2001 John Wiley & Sons, Ltd.
Liquid chromatography ion trap mass spectrometric analysis of oligosaccharides using permethylated derivatives
Authors: Delaney Jeannine , Vouros Paul
Published: August 2002

Reversed phase liquid chromatography was combined with the multiple stage mass analysis capability of an ion trap mass spectrometer for the characterization of permethylated oligosaccharide mixtures. The new method was used to separate the components of an unlabeled permethylated maltooligomer ladder, a 2‐aminobenzamide‐labeled (2‐AB) maltooligomer ladder, a complex mixture of 2AB‐labeled bi‐ (B), tri‐ (T), and tetraantennary (Q) standards, and a mixture of recombinant glycoprotein carbohydrates from soluble CD4 with varying sialic acid (S) content. Using reversed phase HPLC, permethylated mixture components including α and β anomers were separated based on their structures. Fluorescent labeling with 2‐aminobenzamide prior to permethylation was employed for off‐line method development, but was not necessarily required for mass spectral analysis, as permethylation alone improved the ionization and fragmentation characteristics of the molecules. Antennae composition of permethylated derivatives was determined in MS2 where the fragmentation patterns of the Y‐ and B‐ion series predominated, and then further evaluated in MS3, which provided additional information on branching obtained from A and X cross‐ring fragmentation. Copyright © 2001 John Wiley & Sons, Ltd.
m/z‐Selective infrared multiphoton dissociation in a Penning trap using sidekick trapping and an rf‐tickle pulse
Authors: Hofstadler Steven A. , Sannes‐Lowery Kristin A. , Griffey Richard H.
Published: August 2002

We present a novel scheme for performing m/z‐selective infrared multiphoton dissociation (IRMPD) in a Penning trap. Ions are injected into the trapped ion cell of a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer and trapped using the ‘sidekick’ approach. Because this mode of ion trapping can result in an ion cloud precessing about the central axis of the cell with a significant magnetron radius, the effectiveness of conventional on‐axis IRMPD schemes can be adversely affected. Here we demonstrate that the non‐zero magnetron radius of the ion ensemble can be exploited with rf‐tickle pulses which excite, either in an m/z‐selective or broadband mode, the cyclotron frequency of the orbiting ions such that their flight path intercepts the on‐axis laser beam resulting in effective IRMPD. This approach has potential utility in the tandem mass spectrometric characterization of complex mixtures, suggests new approaches for two‐dimensional FTICR studies and, most importantly, represents a straightforward approach to improve the effectiveness of IRMPD for ions captured using sidekick trapping protocols. Copyright © 2001 John Wiley & Sons, Ltd.
Improved thermal decomposition of sulfates to SO2 and mass spectrometric determination of δ34S of IAEA SO‐5, IAEA SO‐6 and NBS‐127 sulfate standards
Authors: Halas Stanislaw , Szaran Janina
Published: August 2002

We describe a significant improvement to our low‐temperature thermal decomposition of sulfates to SO2 for isotopic analysis (Halas S, Szaran J. Anal. Chem. 1999; 71: 3254) that has led to better reproducibility and efficiency of measurements. In the present approach we use a mixture of two reagents, NaPO3 + V2O5, mixed in a weight ratio of 3:5. The addition of V2O5 prevents overboiling of NaPO3 at temperatures, T, increased to 800 °C. Using this modified method we obtained the following δ34S values (in ‰): +21.17 ± 0.12 for NBS‐127, +0.15 ± 0.06 for IAEA SO‐5, and −34.12 ± 0.11 for IAEA SO‐6. Copyright © 2001 John Wiley & Sons, Ltd.
Phytoremediation of arsenic‐contaminated soil as affected by the chelating agent CDTA and different levels of soil pH
Authors: Bagga Davinderjit K. , Peterson Scott
Published: August 2002

Elevated levels of arsenic can pose a major threat to both human health and the environment. The
phytoremediation of heavy metals from soil is emerging as a cost‐effective technology for the
remediation of contaminated soils. The present greenhouse study was undertaken to identify plants capable of
tolerating and accumulating high concentrations of arsenic. Asparagus fern and rye grass were found to tolerate
and accumulate more than 1,100 ppm of arsenic in plant tissue. Arsenic uptake as affected by different levels
of the chelating agent trans‐1, 2‐ cyclohexylenedinitrilotetraacetic acid (CDTA) and
soil pH were also studied. The application of 5 mmol kg−1 of CDTA to
arsenic‐contaminated medium loam field soil enhanced the accumulation of arsenic by the test plants.
Under these conditions, plants accumulated up to 1,400 ppm of arsenic as compared to 950 ppm by the plants
grown in soil containing 1,200 ppm of arsenic but without any amendment of the chelating agent. Plants grown in
field soil of pH 5 containing 300 ppm of arsenic absorbed higher concentrations of arsenic than at other tested
pH levels. Corresponding reductions in arsenic content of soil after plant harvests were observed. © 2001
John Wiley & Sons, Inc.
Human herpesvirus‐6 and ‐7 in transplantation
Authors: Dockrell David H. , Paya Carlos V.
Published: August 2002

Infections with the β‐herpesviruses human herpesvirus‐6 (HHV‐6) and human herpesvirus‐7 (HHV‐7) are ubiquitous in childhood. The immunosuppression secondary to organ or bone marrow transplantation together with posttransplantation management may favour viral replication and reactivation. HHV‐6 and ‐7 induce immunosuppression by targeting lymphocytes, natural killer cells and monocytes. HHV‐6 is commonly detected posttransplantation but variability in definitions of clinical syndromes related to this virus and detection methods have complicated understanding of the clinical relevance of HHV‐6 posttransplantation. Clinical symptoms associated with HHV‐6 include febrile illness, pneumonitis, hepatitis, encephalitis and bone marrow suppression. However, the majority of HHV‐6 infections are asymptomatic. The incidence of HHV‐7 infection and its clinical manifestations posttransplantation are even less well characterised. In addition, HHV‐6 and HHV‐7 are related to CMV disease or acute graft‐versus‐host disease and, indirectly, to increases in resource utilisation. Based on the potential relevance of these two β‐herpesviruses in transplant recipients, further studies are required to establish their real impact in transplantation. For this, sensitive and specific molecular diagnostic techniques allowing for the rapid detection and quantitation of virus and for the analysis of susceptibility to current antiviral agents are required. Copyright © 2001 John Wiley & Sons, Ltd.
RobustH∞control of phase‐locked loops with polytopic type uncertainties
Authors: Suplin V. , Shaked U.
Published: August 2002

A robustH∞control method is applied in the design of loop filters for phase‐locked loop (PLL) carrier phase tracking. The proposed method successfully copes with large S‐curve slope uncertainty and with a significant decision delay in the closed loop that may stem from the decoder and/or the equalizer there. The design problem is transformed into a state‐feedback control problem where phase and gain margins should be guaranteed in spite of the uncertainty. Of all the loop filters that achieve the required margins the one that minimizes an upper bound on the effect of the phase and the measurement noise signals is derived. Copyright © 2001 John Wiley & Sons, Ltd.
H∞control for nonlinear affine systems: a chain‐scattering matrix description approach
Authors: Hong Jang‐Lee , Teng Ching‐Cheng
Published: August 2002

This paper combines an alternative chain‐scattering matrix description with (J,J′)‐lossless and a class of conjugate (−J, −J′)‐lossless systems to design a family of nonlinearH∞output feedback controllers. The present systems introduce a new chain‐scattering setting, which not only offers a clearer expression for the solving process of the nonlinearH∞control problem but also removes the fictitious signals introduced by the traditional chain‐scattering approach. The intricate nonlinear affine control problem thus can be transformed into a simple lossless network and is easy to deal with in a network‐theory context. The relationship among these (J,J′) systems,L2‐gain, and Hamilton–Jacobi equations is also given. Block diagrams are used to illustrate the central theme. Copyright © 2001 John Wiley & Sons, Ltd.
Linear matrix inequality conditions for robustness and control design
Authors: D'Andrea Raffaello
Published: August 2002

In this paper, well‐known stability conditions for linear, time‐invariant systems subject to structured uncertainty are extended to encompass matrix valued and affine integral constraints on the system inputs and outputs. Necessary and sufficient analysis conditions are derived in terms of linear matrix inequalities. For a large class of these problems, the synthesis question can also be expressed as a linear matrix inequality. Copyright © 2001 John Wiley & Sons, Ltd.
Discrete‐time low‐gain control of linear systems with input/output nonlinearities
Authors: Fliegner T. , Logemann H. , Ryan E. P.
Published: August 2002

Discrete‐time low‐gain control strategies are presented for tracking of constant reference signals for finite‐dimensional, discrete‐time, power‐stable, single‐input, single‐output, linear systems subject to a globally Lipschitz, non‐decreasing input nonlinearity and a locally Lipschitz, non‐decreasing, affinely sector‐bounded output nonlinearity (the conditions on the output nonlinearities may be relaxed if the input nonlinearity is bounded). Both non‐adaptive and adaptive gain sequences are considered. In particular, it is shown that applying error feedback using a discrete‐time ‘integral’ controller ensures asymptotic tracking of constant reference signals, provided that (a) the steady‐state gain of the linear part of the plant is positive, (b) the positive gain sequence is ultimately sufficiently small and (c) the reference value is feasible in a very natural sense. The classes of input and output nonlinearities under consideration contain standard nonlinearities important in control engineering such as saturation and deadzone. The discrete‐time results are applied in the development of sampled‐data low‐gain control strategies for finite‐dimensional, continuous‐ time, exponentially stable, linear systems with input and output nonlinearities. Copyright © 2001 John Wiley & Sons, Ltd.
Forward decomposition algorithms for optimal control of a class of hybrid systems
Authors: Cho Young C. , Cassandras Christos G. , Pepyne David L.
Published: August 2002

This paper considers optimal control problems for a class of hybrid systems motivated by the structure of manufacturing environments that integrate process and operations control. We derive new necessary and sufficient conditions that allow us to determine the structure of the optimal sample path and hence decompose a large non‐convex, non‐differentiable problem into a set of smaller convex, constrained optimization problems. Using these conditions, we develop two efficient, low‐complexity, scalable algorithms for explicitly determining the optimal controls. Several numerical examples are included to illustrate the efficacy of the proposed algorithms. Copyright © 2001 John Wiley & Sons, Ltd.
GuaranteedH∞robustness bounds for Wiener filtering and prediction
Authors: Bolzern P. , Colaneri P. , De Nicolao G. , Shaked U.
Published: August 2002

The paper deals with special classes ofH∞estimation problems, where the signal to be estimated coincides with the uncorrupted measured output. Explicit bounds on the difference between nominal and actualH∞performance are obtained by means of elementary algebraic manipulations. These bounds are new in continuous‐time filtering and discrete‐time one‐step ahead prediction. As for discrete‐time filtering, the paper provides new proofs that are alternative to existing derivations based on the Krein spaces formalism. In particular, some remarkableH∞robustness properties of Kalman filters and predictors are highlighted. The usefulness of these results for improving the estimator design under a mixedH2/H∞viewpoint is also discussed. The dualization of the analysis allows one to evaluate guaranteedH∞robustness bounds for state‐feedback regulators of systems affected by actuator disturbances. Copyright © 2001 John Wiley & Sons, Ltd.