bluuebunny/crossref_metadata_2025 huggingface dataset:
Mikrobielle Verwertung von Mischsubstraten
Authors: Weide H.
Published: July 2010

Decomposition of substrates by heterotrophic microorganisms is accomplished in natural biotopes such as in soil and in waters, on or in macroorganisms but also in laboratory and industrial biotopes. The interest of man in these processes is manifold. Starting with the division of substrates into three groups of simple substrates, complex and mixed substrates with or without solid particles their qualitative and quantitative occurrence in nature and their significance in biotechnology will be discussed. In the decomposition of these substrates their utilization by pure cultures or mixed populations is to be exactly distinguished. Simple growth curves, di‐ or polyauxy, sequences of decomposition of simple substrates of a mixed substrate, population changes and successions are only some of the phenomena occurring in this process. The pathways of catabolism are subjected to manifold regulations on the three levels of stoichiometric regulation, the regulation of enzyme activity and the regulation of enzyme synthesis. In natural biotopes there is hardly a constant substrate supply over a longer period. That's why certain mechanisms of regulation are permanently acting. Thus the ‘normal’ physiological state for microorganisms is characterized by permanent transition situations – called ‘transients’. These reactions are also applied to many biotechnological processes.
Lysogenie und lysogene Konversion bei methylotrophen Bakterien I. Nachweis des lysogenen Zustandes des fakultativ methanolassimilierenden Stammes Acetobacter MB 58/1 und Charakterisierung seines temperenten Phagen MO 1
Authors: Wünsche L. , Fischer H. , Kiesel B.
Published: July 2010

Lysogeny could until now not be shown for methylotrophic bacteria or for Acetobacter. In this paper we demonstrate the lysogenic state in a methylotrophic strain of the genus Acetobacter. The responsible temperate phage MO 1 belongs to group A of BRADLEY's classification system and contains double stranded DNA. Phage MO 1 was characterized by the following properties: Host range, sensitivity against environmental factors, serological behaviour, burst size, and latent period in one‐step growth experiments, and especially by its response to inducing factors.
Elektronenmikroskopische Untersuchung an Komplexen von DNA mit der Restriktionsendonuclease SalGI
Authors: Johannssen W.
Published: July 2010

The binding properties of the type II restriction endonuclease SalGI to the plasmid DNA pGW 10 has been investigated by electron microscopic studies. Samples were spread by the BCA technique. In the presence of magnesium, SalGI binds as dimers and tetramers to the specific recognition site 5′‐G‐T‐C‐G‐A‐C‐3′ and with lower rate to the sequence 5′‐G‐T‐C‐A‐A‐C‐3′, which represents the recognition site of the restriction endonucleases Hind II and Hinc II.
Preparation and partial characterization of Xanthomonas oryzae phytotoxin
Authors: Dubey R. S.
Published: July 2010

A synthetic medium containing ammonium nitrate, urea, D‐glucose, glycerol, and sodium glutamate was developed for growth of Xanthomonas oryzae and preparation of its phytotoxin. Culture filtrates and partially purified toxin preparations caused blight symptoms when inoculated in leaves of 30 days old rice plant cv. T(N) I. Toxin elicited quicker response than living cells. This activity was due to a non‐dialysable, partial acid and heat labile glycopeptide. There was a sharp decrease in activity when culture filtrates and crude toxin preparations were heated at 100°C for 30 min. Maximum activity was observed in pH range of 6.0–7.0 and a gradual loss at lower pH (5.0–3.0) and higher pH values (8.0–10.0). Unlike living cells which caused continuous lesion enlargement, toxin inoculation caused maximum attainment of lesion length within 4–6 weeks. Toxin preparation in concentration of 45 μg glucose/ml failed to evoke response.

The study demonstrates that the purified toxin being easy in storage and causing quicker response than living cells when inoculated in rice leaves, may be used to screen rice varieties for bacterial blight resistance.
Protoplastenfreisetzung und Regeneration des Ascomyceten Hypomyces ochraceus (PERS.) TUL
Authors: Riemay K. H. , Ellrich Silvia , Tröger R.
Published: July 2010

A rapid and convenient method for producing protoplasts from 3 d old mycelium of the ascomycete Hypomyces ochraceus is described. The procedure involves a Helix pomatia enzyme preparation and sucrose (20%) for stabilization. Pretreatment with disulfide bond reducing agents reduced the amount of viable protoplasts. Formation of protoplasts and different stages of regeneration were observed by phase contrast microscopy. There was only one type of true regeneration from protoplasts to hyphae in 15–30% gelatine medium by direct forming a germ tube from the original protoplast. Cytological events and physiological conditions are discussed.
Fluoride‐induced filaments of Erwinia carotovora
Authors: Gashe B. A. , Grula M. M.
Published: July 2010

Sodium fluoride induces filamentous growth of Erwinia carotovora when it is grown in liquid media containing aspartic acid only as the sole source of nitrogen. It is proposed that a stable complex of F−‐Mg2+‐enzyme and PO, resulting in Mg2+ deficiency and consequent inability of E. carotovora cells to oxidize aspartic acid normally, is responsible for the formation of filaments in the presence of fluoride ions.
Growth ofCandida albicanson artificialD‐glucose derivatives
Authors: Hrmová M. , Šturdík E. , Košík M. , Gemeiner P. , Petruš L.
Published: July 2010

Growth ofCandida albicanson artificial D‐glucose derivatives (amino‐, methyl‐, acylglycosides and N‐acetyl‐D‐glucosamine derivatives) was examined with the aim to find new inducers of the mycelial growth form. For representatives of particular groups (α‐D‐glucopyranosylamine, D‐glucose and N‐acetyl‐D‐glucosamine) some physiological (growth, doubling time, specific growth rate, oxygen uptake and CO2production, respiration quotients), biochemical (dry weight yield, protein content, ethanol production), and morphological parameters (length‐width quotient, volume, percentage of budding cells) of cultures in different growth phases were determined with regard to the type and concentration of carbon source. The results obtained may be valuable for studies of the structure‐utilization relationships of carbohydrate derivatives as well as for the elucidation of yeast‐mycelial transition inCandida albicansinduced by unphysiological hexoses degradable intracellularly.
Verbesserung der Y‐Werte bei Wachstum von Hansenula polymorpha auf Methanol durch simultane Verwertung von Glucose
Authors: Müller R. , Markuske K. D. , Babel W.
Published: July 2010

The simultaneous utilization of methanol and glucose by Hansenula polymorpha MH20 was investigated in chemostat (C‐limited) cultivation. The mixed‐substrate utilization results in biomass yields which are greater up to 20 to 25% as expected assuming an additive growth on both substrates. This is referred to as an auxiliary‐substrate effect. Additionally, methanol can be utilized at higher growth rates in the presence of glucose compared to those obtained on this substrate alone. The extend of the auxiliary‐substrate effect and the optimum ratio of substrates to reach this effect depend on dilution rate. The greatest stimulation in yield is obtained at D ∼ 0.1 h−1, after raising the dilution rate this effect diminishes. At a rate of 0.1 h−1 the optimum mixed‐substrate ratio of methanol: glucose is 7: 1(g). By increasing the growth rate the ratio changes toward glucose and reached a value of 1:1 (g) at D = 0.3 h−1. This change in the optimum ratio correlates with diminution in yield coefficient of methanolp accomanying an increase in growth rate > 0.15 h−1. Energy balances of the utilization of the single substrates are used for interpretation of these results. From this it is evident that methanol does not play the role of an energy‐rich substrate in the metabolism of yeast. Rather glucose is the energy‐providing substrate in this combination.
Inhibition of photosystem II of nitrogen‐fixing blue‐green alga Nostoc linckia by the rice‐field herbicide benthiocarb
Authors: Singh R. K. , Singh B. D. , Singh H. N.
Published: July 2010

Effects of rice‐field herbicide benthiocarb (S‐(4‐chlorobenzyl)‐N,N‐diethyl thiolcarbamate) was studied on the nitrogen‐fixing blue‐green alga Nostoc linckia. The herbicide caused inhibition of growth and heterocyst formation, an increase in intensity of photoacoustic signals, and a four‐fold reduction in oxygen evolution, but did not affect dark O2‐uptake. The inhibition of growth and heterocyst formation was relieved by 500 μg/ml glucose. A Het−Nif− mutant of Nostoc muscorum failed to show an increase in reversion frequency after treatment with 10 μg/ml benthiocarb for 1 hr.
Effects of cycloheximide on the temperature profile ofSacharomyces cerevisiae
Authors: Madeira‐Lopes A. , van Uden N.
Published: July 2010

Tmax, the maximum temperature for growth ofSaccharomyces cerevisiae, decreased linearly with increasing concentrations of cycloheximide added to the medium, to about 20 °C at 2.5 μg ml−1. In this concentration range thermal death was not enhanced. The ARRHENIUS plot of growth was shifted to lower temperatures as a function of the cycloheximide concentrations and became dissociated from the ARRHENIUS plot of thermal death. It was concluded that the target site of cycloheximide, the cytoplasmic ribosome, is not identical with the physiologicalTmaxsite ofS. cerevisiaeand that the binding of cycloheximide to its target sites is strongly enhanced by the temperature.
Growth measurements by monitoring light scattering of a filamentous blue‐green alga which does not give uniform and stable suspension in culture vessels
Authors: Adhikary S. P.
Published: July 2010

It has been tried to adapt the light scattering technique to measure the growth of a filamentous blue‐green alga Westiellopsis profilica JANET which does not give stable and uniform suspension during its growth in culture vessels. Experiments were conducted to make stable suspensions of the organism and the results on the scattering and spectral studies were compared with that of Microcystis sp. which gives a uniform and stable suspension in culture vessels.

Some conventional experiments were performed to show that the growth of the blue‐green alga, Westiellopsis prolifica does not run with the rate of pigment metabolism. It has also been observed that the alterations in size, shape, swelling and shrinkage and average cell characteristics of the alga resulted from alterations in physical and chemical characteristics of the culture media, significantly change the scattering values without much or any change in their growth rate in term of dry weight values.
Bildung von Phaseolotoxin und Phosphosulfamylornithin durch Pseudomonas syringae pv. phaseolicola in Submerskultur
Authors: Bublitz F. , Völksch Beate
Published: July 2010

Phaseolotoxin (Nδ‐phosphosulfamyl‐ornithyl‐alanyl‐homoarginine) from culture‐supernatants of Pseudomonas syringae pv. phaseolicola and Nδ‐phosphosulfamylornithine (PSOrn) obtained from phaseolotoxin by treatment with leucine aminopeptidase were compared in regard to their inhibition effects by means of the enzymatic toxin test as well as by bioassay. In the enzymatic toxin test PSOrn exhibits an inhibiting effect five times stronger than that of phaseolotoxin. The maximal inhibition due to PSOrn is also higher. On the other hand, only phaseolotoxin caused growth inhibition in the bioassays used (indicator organisms: Escherichia coli, Euglena gracilis). Tests are presented which allow to detect these compound selectively. Their application showed that the strain studied produced phaseolotoxin as well as PSOrn in submerged cultures.
Double or triple sets of replication functions as inverted and direct repeats on in vitro reconstructed streptococcal MLS resistance plasmids
Authors: Behnke D. , Klaus S.
Published: July 2010

In vitro rearrangement of plasmid pDB102 together with comparative studies of other streptococcal plasmids allowed the localization of replication and copy control functions on sequences which were present on pDB102 and its naturally occurring ancestor pSM19035 as duplicates in inverted orientation. Evidence is presented that neither the presence of duplicate replication regions nor their arrangement in inverted orientation was essential for plasmid survival. Among the in vitro reconstructed plasmids were several that stably carried two or three sets of replication and copy control functions either as inverted or direct repeats or both. A copy control mutation is described which led to a tenfold increase of copy number over that of the naturally occurring plasmid pSM19035.
Uncoupling of respiration in turimycin fermentations
Authors: Effenberger W. , Müller P. J. , Bocker H.
Published: July 2010

Results furnish evidence for a partial uncoupling of respiration at conditions of phosphate limitation in turimycin fermentations. The uncoupling was primarily caused by the high intracellular ATP hydrolase activity and probably also by the CN‐resistant respiration. The results support the idea that high dephoshorylating enzyme activities may have a regulatory effect on the secondary product biosynthesis.
Wirkung supraoptimaler Temperaturen auf Wachstum und Entwicklung einer Brennereihefe I. Wachstum und Entwicklung der HefeSaccharomyces cerevisiae, Stamm 193 bei diskontinuierlicher Kultur
Authors: Mavrina L. , Pozmogova I. , Schade W.
Published: July 2010

The influence of supraoptimal temperatures on a distillery yeast was investigated. Supraoptimal temperatures below 40 °C reduced the biomass production but did not cause the death of the culture after several generations.

At 42° to 44 °C the yeast cells lost their ability of propagation after one or two generations without showing an intracellular deficit of phosphorus‐containing repairing components. The separation of daughter cells from mother cells was rendered more difficult. The appearance of abundand doubled cells was characteristic. The contents of RNA and protein decreased to 41% or 80%, respectively. Rates of14C‐uracil and14C‐leucine incorporation showed that the synthesis of RNA was repressed stronger than that of proteins by the high temperature treatment at 42° to 44 °C. The effectivity of energy metabolism of the cultivated yeast cells was low at supraoptimal temperatures. The yeast showed a strongly enhanced activity of fermentation and an accumulation of polysaccharides.
Enzym‐Induktion in der Hefe Lodderomyces in Gegenwart von n‐Alkanen
Authors: Müller H.‐G. , Mauersberger S. , Schunck W.‐H. , Wiedmann B.
Published: July 2010

The utilization of n‐alkanes is connected with extensive modifications of the yeast cell, especially of the cytochrome P‐450‐containing membrane. Beside the cytochrome P‐450 the NADPH cytochrome P‐450 reductase, the cytochrome b5, long‐chain alcohol and long‐chain aldehyde dehydrogenases are induced. The activity of the alkane‐hydroxylating enzyme system grows more than the concentration of its terminal oxidase. The induction of the cytochrome P‐450 is inhibited by cycloheximide. A low concentration of oxygen in the culture medium amplifies the induction both of the alkane‐hydroxylating enzyme system and of catalase and cytochrome oxidase, which are localized in the peroxisomes and mitochondria, respectively.
Use of D‐glucosamine and 2‐deoxyglucose in the selective isolation of mutants of the yeast Lipomyces starkeyi derepressed for the production of extracellular endodextranase
Authors: Laires A. , Spencer‐Martins I. , van Uden N.
Published: July 2010

The glucose analogues 2‐deoxyglucose and D‐glucosamine repressed the production of extracellular endodextranase in the yeast Lipomyces starkeyi. Though both analogues were successfully used for the selective isolation of derepressed and hyperproductive mutants, 2‐deoxyglucose proved to be superior to D‐glucosamine with respect to effective concentration and the avoidance of background growth.
Production of oxalic acid by some fungi infected tubers
Authors: Faboya O. , Ikotun T. , Fatoki O. S.
Published: July 2010

Oxalic acid (as oxalate) was detected in four tubers commonly used for food in Nigeria – Dioscorea rotundata (White yam), Solanum tuberosum (Irish potato), Ipomoea batatas (Sweet potato), and Manihot esculenta (cassava). Whereas healthy I. batata had the highest oxalic acid content, healthy M. esculenta contained the lowest. When all tubers were artificially inoculated with four fungi — Penicillium oxalicum CURIE and THOM, Aspergillus niger VAN TIEGH, A. flavus and A. tamarii KITA, there was an increase in oxalate content/g of tuber tissue. The greatest amount of oxalate was produced by P. oxalicum in D. rotundata tuber. Consistently higher amounts of oxalate were produced by the four fungi in infected sweet potato tuber than in any other tuber and consistently lower amounts of oxalate were produced by the four fungi in Irish potato tuber. Differences in the carbohydrate type present in the tubers and in the biosynthesis pathway are thought to be responsible for variation in the production of oxalate in the different tubers by the four fungi used.
Wirkung von Ölen und Fettsäuren auf Wachstum und Enzymbildung bei Thermoactinomyces vulgaris III. Einfluß von Kulturgefäßen, Stammaterial und Medienzusammensetzung
Authors: Leuchtenberger A. , Ruttloff H.
Published: July 2010

The influence of rape‐oil as antifoam agent on growth and protease synthesis of T. vulgaris was studied. The turbulence and the aeration conditions caused by the culture vessel have a fundamental importance for the so‐called oil effect. A higher aeration rate induces an enhanced lysis of the mycelium and consequently a reduced enzyme synthesis. The tentency to lysis of the mycelium at different selectants is variable. The addition of oil to the culture medium reduces this tendency and promotes the protease production. The oil effect on the enzyme synthesis is higher in deficient medium than in full one.
Isolierung und Rekonstitution des Alkan‐Monooxygenase‐Systems der Hefe Lodderomyces elongisporus
Authors: Schunck W.‐H. , Riege P. , Honeck H. , Müller H.‐G.
Published: July 2010

It is generally assumed that the first step of alkane degradation in several yeast strains and bacteria is catalyzed by a monooxygenase system containing cytochrome P‐450 as the terminal oxidase and a NADPH‐cytochrome P‐450 reductase as the electron transfer component. To prove this hypothesis both proteins were purified to homogeneity from the microsomal fraction of the alkane‐assimilating yeast L. elongisporus and reconstituted in vitro.

The cytochrome P‐450, having a specific content of 12–17 nmoles/mg protein turned out to be a typical member of this class of hemoproteins with respect to the molecular weight (53 500) and spectral properties.

The reductase component with a molecular weight of 79000 contains FAD and FMN as prosthetic groups.

The recombination of the hemoprotein and the flavoprotein results in an enzyme system which catalyzes the monoterminal hydroxylation of hexadecane.

The activity of the reconstituted enzyme system is remarkably stimulated by nonionic detergents, suggesting the requirement of an additional lipid factor. The possible importance of other electron transfer systems and of substrate transport is discussed with respect ot the function of the alkane monooxygenase system under in vivo conditions.
The effect of varying concentrations of Mg2+ and ATP upon the kinetic behaviour of dihydroxyacetone kinase from the methanol‐assimilating yeast Candida methylica
Authors: Hofmann K. H. , Babel W.
Published: July 2010

The phosphorylation of dihydroxyacetone by means of the enzyme dihydroxyacetone kinase (DHAK) is a key reaction in the assimilation of methanol in yeasts. In the present paper the influence of varying concentrations of Mg2+ ions and ATP upon the reaction rate of DHAK from Candida methylica is described and the regulatory consequences for the assimilation of methanol by yeasts are discussed.
Konjugativer Plasmidtransfer von A‐, B und H‐Streptokokken auf N‐Streptokokken
Authors: Riemelt I. , Kirchhübel W. , Malke H.
Published: July 2010

Plasmid‐mediated resistance to erythromycin and chloramphenicol was successfully transferred from group A, B and H streptococci to group N streptococci by a process akin to conjugation. The results showed that plasmids from streptococcal groups other than N were able to replicate in lactic streptococci as well.

The transfer experiments were carried out by using a membrane filter mating technique. Four of the five plasmids used (pSM15346, pSM10419, pIP501, and pEL1) were transferred at frequencies ranging from 10−1 to 10−8 transconjugants per donor colony‐forming unit. The highest transfer frequencies were obtained when S. pyogenes strain 15346 (pSM15346) served as the donor strain. The identy of transconjugants was verified by testing for the presence of unselected markers of the recipient strains, and both transduction and transformation were ruled out as the mechanisms of transfer.
Effect of a focal articular defect on cartilage deformation during patello‐femoral articulation
Authors: Wong Benjamin L. , Sah Robert L.
Published: July 2010

The objective of this study was to determine cartilage strains near, and in apposition to, a focal defect during patello‐femoral articulation. Bovine osteochondral blocks from the trochlea (TRO) and patella (PAT) were apposed, compressed 12%, and subjected to sliding under video microscopy. Samples, lubricated with synovial fluid, were tested intact and then with a full‐thickness defect in PAT cartilage. Shear (Exz), axial (Ezz), and lateral (Exx) strains were determined locally for TRO and PAT cartilage. For articulation with a focal defect, the strain amplitudes of PAT cartilage near the surface were ∼2–8× lower in Exz and ∼1.4× higher in −Ezz than intact PAT cartilage. At 20% depth, Exz and Exx for PAT cartilage with a focal defect were ∼2× and ∼10–25× higher than intact PAT, respectively. For TRO articulating against a focal defect, Exz and −Ezz near the surface and at 20% depth were ∼2–4× lower than that for articulation against intact cartilage. The results elucidate dramatic region‐specific changes in strain due to lateral motion. In these regions, such altered cartilage mechanics during knee movement may cause focal defects to extend by induction of damaging levels of strain to bordering regions of cartilage. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1554–1561, 2010
Multimodal imaging guidance for laser ablation in tracheal stenosis
Authors: Murgu Septimiu D. , Colt Henri G. , Mukai David , Brenner Matt
Published: July 2010

Objective/Hypothesis:

Laser‐induced damage of tracheal wall microstructures might contribute to recurrence after bronchoscopic treatment of tracheal strictures. The purpose of this study was to demonstrate how multimodal imaging using white light bronchoscopy (WLB), endobronchial ultrasound (EBUS), and optical coherence tomography (OCT) might identify in vivo airway wall changes before and resulting from Nd:YAG laser ablation and dilation of tracheal stenosis.

Study Design:

Case study.

Methods:

Commercially available WLB, high frequency EBUS using a 20‐MHz radial probe and time‐domain, frontal imaging OCT systems were used to characterize the extent, morphology, and airway wall microstructures at the area of hypertrophic fibrotic tissue formation before, during and after treatment of postintubation tracheal stenosis.

Results:

WLB revealed the location of a complex, extensive, severe stricture. EBUS showed a homogeneous layer overlying a hyperechogenic layer corresponding to disrupted cartilage. OCT showed a homogeneous light backscattering layer and absence of layered microstructures, confirming absence in close proximity of normal airway wall. After laser ablation, OCT of charred tissue showed high backscattering and shadowing artifacts. OCT of noncharred tissue showed a thinner, homogeneous, light backscattering layer. EBUS showed thinner but persistent hypertrophic tissue suggesting incomplete treatment. WLB revealed improved airway patency postprocedure and recurrence 3 weeks later.

Conclusions:

EBUS identified cartilage disruption and residual hypertrophic tissue, the evidence of which might contribute to recurrence. OCT revealed homogeneous light backscaterring representing persistent noncharred hypertrophic tissues but it did not visualize cartilage disruption. Future studies are warranted to confirm whether these technologies can help guide bronchoscopic treatments.
The effects of human trampling on the microbiological properties of soil and vegetation in mediterranean mountain areas
Authors: Lucas‐Borja M. E. , Bastida F. , Moreno J. L. , Nicolás C. , Andres M. , López F. R. , Del Cerro A.
Published: July 2010

Increased tourist activity and recreational use of wilderness and other protected areas has endangered zones of high environmental value. The aim of this work was to evaluate the effects of trampling intensity (low, high use trails and untrampled trails) and distance from the trails (on the trails, at 10 and 20 m from the trails) on the vegetation, chemical, physical and microbiological properties of a soil in Mediterranean mountain areas. Trail type and distance from the trail significantly influenced several parameters. High use trails showed lower values of plant cover and diversity of vegetation species, as well as soil respiration and some enzyme activities (phosphatase, β‐glucosidase and dehydrogenase) than low use trails. In addition, the effects of trampling spatially extended further from these high use trails than from low use trails. Statistical analysis showed that some microbiological (basal respiration, dehydrogenase activity and β‐glucosidase activity) and vegetal parameters (plant cover and diversity) may be established as a set of indicators for the evaluation of soil quality on these areas subjected to human trampling. We concluded that trampling significantly impacts on soil microbial processes and vegetal communities, and visitor should be restricted from entering ecologically sensitive areas due to the effects of trampling. Copyright © 2010 John Wiley & Sons, Ltd.
Charge and Size Dependence of Liposome Diffusion in Semidilute Biopolymer Solutions
Authors: Rusu Laura , Lumma Dirk , Rädler Joachim O.
Published: July 2010

The diffusion of liposomes and PL/DNA complexes in mucin and collagen solutions, considered to model ‘in vivo’ colloidal gene delivery vector transport, is studied with FCS. The diffusion of defined liposomes is investigated as a function of particle size, surface charge, and the deviation from the Stokes‐Einstein behavior. In all cases the self‐diffusion coefficient decreases exponentially with polymer concentration. The same surface charge dependence of diffusion is observed in mucin for PL/DNA complexes with either positive or negative excess charge. Incubation of positively‐charged PL/DNA complexes in a natural lung surfactant lipid increases the diffusion coefficients to almost the same as for the negatively‐charged PL/DNA complexes.

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Photocurable Shape‐Memory Copolymers of ε‐Caprolactone and L‐Lactide
Authors: Nagata Minoru , Yamamoto Yu
Published: July 2010

Biodegradable and photocurable block copolymers of ε‐caprolactone and L‐lactide were synthesized by polycondensation of PLLA diol ($\overline {M} _{{\rm n}} $ = 10 000 g · mol−1), PCL diol ($\overline {M} _{{\rm n}} $ = 10 000 g · mol−1), and a chain extender bearing a coumarin group. The effect of copolymer composition on the thermal and mechanical properties of the photocured copolymers was studied by means of DSC and cyclic tensile tests. An increase in Young's modulus and a decrease in the tensile strain with increasing PLLA content was observed for the block copolymers. Block copolymers with high PCL content showed good to excellent shape‐memory properties. Random copolymers exhibited Rf and Rr values above 90% at 45 °C for an extremely large tensile strain of 1 000%.

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Indication of Local Phase Separation in Polyimide/Silica Hybrid Polymers
Authors: Bartolotta Antonino , Calandra Pietro
Published: July 2010

PI/SiO2 hybrid polymers involving the in situ generation of SiO2 particles through the sol/gel route have emerged as promising materials in many fields of modern technology thanks to their unique structural characteristics. In this paper their structural and dynamic properties were investigated by FT‐IR and DMTA as a function of SiO2 content. All data consistently highlight a loosening of polymeric structure due to the presence of SiO2 nanoparticles and suggest a silica‐induced structural change most probably due to a sub‐micrometer scale SiO2 phase separation. Our results demonstrate how the analysis of sub‐glass γ‐relaxation dynamics can be exploited to investigate sub‐micro phase segregation in such materials.

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1H NMR Determination of the Doping Level of Doped Polyaniline
Authors: Wang Xing , Sun Taolei , Wang Chunyu , Wang Ce , Zhang Wanjin , Wei Yen
Published: July 2010

1H NMR spectroscopy is an important method to obtain detailed structural information about polymers. In this study, we demonstrate the assignment of a new set of triplet peaks (sharp, equal‐strength, and equidistant peaks at δ = 6.97, 7.07, and 7.17 with a coupling constant of 51.1 Hz) in 1H NMR spectra for doped PANI, which are directly correlated with the protonation of the PANI backbone. The H/D exchange, dedoping, and redoping procedures supply the experimental proofs. Analyses show that the integral area ratio of the triplet peak is dependent on the effective doping of PANI and has a clear relationship with the conductivity. It thus provides a quantitative tool to evaluate the doping nature of PANI.

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Quantitative assessment of left ventricular function in humans at 7 T
Authors: Brandts Anne , Westenberg Jos J. M. , Versluis Maarten J. , Kroft Lucia J. M. , Smith Nadine B. , Webb Andrew G. , de Roos Albert
Published: July 2010

The purpose of this study was to determine the ability of 7 T cardiac magnetic resonance imaging (MRI) to quantitatively assess left ventricular volumes, mass, and function from cine short‐axis series and left ventricular diastolic filling from velocity‐encoded MRI in 10 healthy volunteers. As comparative “gold standard,” the corresponding measures obtained at 1.5 T were taken. Left ventricular volumes, function, and mass were obtained by manual image segmentation. Trans‐mitral flow graphs were obtained from 2D one‐directional through‐plane velocity‐encoded MRI planned at the mitral valve in end‐systole. Imaging at 7 T MRI was successful in 80% of the examinations. Assessment of left ventricular volumes, function, and mass at 7 T showed good agreement with 1.5 T (no significant differences between variables describing volumes, function, and mass with intraclass correlation coefficients ranging from 0.77 to 0.96). Trans‐mitral stroke volume and the ratio between early and atrial peak filling rate showed strong agreement at both field strengths (no significant differences between stroke volumes and filling ratios with intraclass correlation coefficients 0.92 for stroke volumes and 0.77 for peak filling ratios). In conclusion, this study shows that assessing left ventricular volumes, function, and flow is feasible at 7 T MRI and that standardized MRI protocols provide similar quantitative results when compared with 1.5 T MRI. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Acoustic noise‐optimized verse pulses
Authors: Schmitter S. , Bock M.
Published: July 2010

Variable‐rate selective excitation RF pulses modulate the slice selection gradients during RF transmission, especially to reduce the total RF power. Amplitude‐modulated slice selection gradients can lead to increased gradient noise, in particular in high‐field MRI where variable‐rate selective excitation techniques are often used. In this work, an algorithm is presented that calculates a variable‐rate selective excitation pulse modulation from given RF pulses with constant slice selection gradient. The algorithm avoids the known acoustic resonance frequencies of the gradient system to minimize sound pressure levels. It was tested with four different slice‐selective RF pulse shapes (Sinc, Gaussian, and two Shinnar‐LeRoux). Sound measurements revealed a reduction of the mean sound pressure level by up to 13dB, and simultaneously, the specific absorption rate was reduced by 55%. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
A convexity‐based homotopy method for nonlinear optimization in model predictive control
Authors: Bonilla Julián , Diehl Moritz , Logist Filip , De Moor Bart , Van Impe Jan F. M.
Published: July 2010

This paper presents a convexity‐based homotopy solution procedure to non‐convex optimal control problems (OCPs) arising in model predictive control. The approach deals with a special class of OCP formulations, where the dynamic system involved is control‐affine and the objective is a penalty on deviations from a state reference trajectory. The non‐convex OCP is modified by introducing a penalized pseudo state and a homotopy parameter which gradually transforms the original problem into a convex one. The method solves first this convex formulation and uses the result to initialize the solution of the next problem on the zero path, recovering the original OCP. The proposed methodology is evaluated for the benchmark control problem of an isothermal chemical reactor with Van de Vusse reactions and input multiplicity. For the simple case with control horizon one, the method is able to find the global solution due to the convex initialization, while local optimization techniques only lead to a local minimum. Copyright © 2010 John Wiley & Sons, Ltd.
Preparation and characterization of polypyrrole with dispersed metallic rhodium particles
Authors: Stochmal Edyta , Hasik Magdalena , Turek Wincenty , Bernasik Andrzej , Adamczyk Anna , Plis Agnieszka , Litynska‐Dobrzynska Lidia
Published: July 2010

Polypyrrole (PPy) with dispersed metallic Rh particles has been prepared by all‐chemical route, i.e. reduction of Rh3+ ions existing in RhCl3 aqueous solutions with sodium borohydride (NaBH4) carried out in the presence of the previously obtained PPy doped with chloride ions (PPyCl). PPy–Rh composites thus formed have been characterized using X‐ray diffraction (XRD), scanning and transmission electron microscopies (SEM, TEM) combined with energy dispersive X‐ray (EDX) microanalysis, Rh3d X‐ray photoelectron (XPS), and IR spectroscopies. This has made it possible to find out that metallic Rh nanoparticles, mainly of sizes below 10 nm, have been present in the composites. Agglomerates, with sizes up to 0.7 µm, have been formed in the systems containing higher amounts of Rh. PPy serving as the matrix in the composites has been doped. However, its doping level has been lower than that of the starting PPyCl. This has been explained by partial reduction of the polymer occurring during preparation of the composites.

Catalytic properties of the PPy–Rh systems have been investigated using isopropyl alcohol conversion as a test reaction. It has been established that the composites are active redox catalysts. This makes them promising materials for applications as catalysts of various redox processes. Copyright © 2010 John Wiley & Sons, Ltd.
Utilization of the smoking cessation medicine varenicline: an intensive post‐marketing study in New Zealand
Authors: Harrison‐Woolrych Mira , Ashton Janelle
Published: July 2010

Purpose

To examine the utilization of varenicline during the first year of marketing in New Zealand (NZ) and to examine how this compares with the dosing instructions recommended in the Champix® product information.

Methods

Dispensing records for all NZ patients prescribed varenicline were collected by the Intensive Medicines Monitoring Programme (IMMP) during the first year this medicine was available in this country. Analyses of these data included patient characteristics and patterns of usage—in particular the duration of treatment dispensed as the first course. An assessment of the effectiveness of varenicline in post‐marketing use was also performed on a sub‐group of the cohort for whom follow‐up information was available.

Results

Of 3415 patients in the first year IMMP cohort, only 125 patients (4%) were dispensed the recommended 12 weeks varenicline treatment. 1299 (38%) were dispensed 14 days treatment (most often as a Starter Pack), 766 (22%) were dispensed 6 weeks, 411 (12%) were dispensed 4 weeks and 332 (8%) patients were dispensed more than 12 weeks treatment as a continuous course. The most common reasons for stopping varenicline prematurely were adverse reactions and cost of treatment. In a subgroup of 1299 patients, varenicline was reported to have been effective for 359 (28%) patients.

Conclusions

In ‘real‐life’ post‐marketing use, most patients did not receive 12 weeks varenicline treatment as recommended in the Champix product information. This observation may have implications for the effectiveness of this smoking cessation medicine. Copyright © 2010 John Wiley & Sons, Ltd.
The experiences, needs and concerns of younger women with breast cancer: a meta‐ethnography
Authors: Adams Eike , McCann Lisa , Armes Jo , Richardson Alison , Stark Daniel , Watson Eila , Hubbard Gill
Published: July 2010

Objective: This meta‐ethnography synthesises the evidence on the experiences, needs and concerns of younger women with breast cancer.

Methods: Using a method called ‘reciprocal translation’ we developed a conceptual model to reflect the local and social contexts, issues, processes, needs and concerns of importance in this literature.

Findings: Key findings relate to the particular point in the life‐course at which young women with breast cancer stand. Issues for these women relate to feeling different as a result of cancer, fear of recurrence, feeling ‘out of sync’ and altered embodied subjectivity. Young women with breast cancer use three processes to integrate the changes that cancer brings, namely, balancing, normalising and changing. Our conceptual model also highlights young women's needs, primarily for support, information, childcare, counselling and spiritual support. Areas of reproduction, fertility and sexuality were also of particular concern. The included papers have methodological limitations that impact on our findings, such as opportunistic data analyses, lack of theoretical frameworks and limited reference to socio‐cultural factors.

Conclusion: The conceptual model developed as a result of this meta‐ethnography provides a basis for practitioners to address these young women's concerns more adequately and comprehensively. Copyright © 2010 John Wiley & Sons, Ltd.
Measurement of airway ion transport assists the diagnosis of cystic fibrosis
Authors: Middleton Peter G. , House Hugh H.
Published: July 2010

The nasal potential difference (PD) demonstrates the increased Na absorption and decreased Cl secretion typically found in cystic fibrosis (CF). It provides useful information for diagnostic purposes and measures the effect of new treatments on the ion transport defects found in CF. This study summarizes the nasal PD results in the respiratory tract of different groups of subjects, examines the responses in squamous epithelia and evaluates new ways to consider nasal PD results.

Nasal PD was tested using the standard protocol of baseline, amiloride, low chloride, and isoproterenol solutions in 40 healthy non‐CF volunteers, 46 CF subjects, and 78 subjects referred for investigation of possible CF. Nasal PD was also measured in the squamous epithelium at the anterior nares in six non‐CF subjects.

Baseline PD was elevated in the CF (47.5 (1.7) mV) compared with non‐CF subjects: (14.0 (0.8) mV, P < 0.00001). Combined [Cl + Isop] responses were smaller in the CF (−0.1 (0.4) mV) compared with the non‐CF subjects (26.2 (1.2) mV, P < 0.00001). In the diagnostic cohort 58 were given a non‐CF diagnosis, 16 had CF confirmed, but 4 remained indeterminate. Separate consideration of Na and Cl transport was easily portrayed through X–Y plots. Finally, the nasal PD responses of squamous epithelium showed high baseline values, but little response to amiloride and low chloride solutions.

The nasal PD provides useful information in the diagnostic algorithm of CF, and in the delineation of the two ion transport defects characteristically found in the respiratory epithelium. Avoidance of the squamous epithelium remains an important consideration for those performing and interpreting nasal PD responses. Pediatr. Pulmonol. 2010; 45:789–795. © 2010 Wiley‐Liss, Inc.
The respiratory management of patients with duchenne muscular dystrophy: A DMD care considerations working group specialty article
Authors: Birnkrant David J. , Bushby Katharine M.D. , Amin Raouf S. , Bach John R. , Benditt Joshua O. , Eagle Michelle , Finder Jonathan D. , Kalra Maninder S. , Kissel John T. , Koumbourlis Anastassios C. , Kravitz Richard M.
Published: July 2010

In 2001, the Muscular Dystrophy Community Assistance, Research and Education Amendments (MD‐CARE Act) was enacted, which directed federal agencies to coordinate the development of treatments and cures for muscular dystrophy. As part of the mandate, the Centers for Disease Control and Prevention (CDC) initiated surveillance and educational activities, which included supporting development of care considerations for Duchenne muscular dystrophy (DMD) utilizing the RAND/UCLA Appropriateness Method (RAM). This document represents the consensus recommendations of the project's 10‐member Respiratory Panel and includes advice on necessary equipment, procedures and diagnostics; and a structured approach to the assessment and management of the respiratory complications of DMD via assessment of symptoms of hypoventilation and identification of specific thresholds of forced vital capacity, peak cough flow and maximum expiratory pressure. The document includes a set of Figures adaptable as “pocket guides” to aid clinicians. This article is an expansion of the respiratory component of the multi‐specialty article originally appearing in Lancet Neurology, comprising respiratory recommendations from the CDC Care Considerations project. Pediatr. Pulmonol. 2010; 45:739–748. © 2010 Wiley‐Liss, Inc.
Surface plasmons with phase singularities and their effects on matter
Authors: Andrews D. L. , Babiker M. , Lembessis V. E. , Al‐Awfi S.
Published: July 2010

We explain how a surface plasmon optical vortex can be created when a laser beam with a phase singularity such as Laguerre–Gaussian light is totally internally reflected at the planar surface of a dielectric on which a metallic thin film is deposited. The light field in the vacuum region is evanescent in that it decays with distance perpendicular to the film surface, but significantly, it retains the phase singularity of the original light beam and also the orbital angular momentum carried by that beam. We describe the essential features of such surface optical vortices and discuss how they can, in principle, be used to influence atoms localised in the vicinity of the surface. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Erratum: Modelling c‐Si/SiNx interface recombination by surface damage
Authors: Steingrube Silke , Altermatt Pietro P. , Schmidt Jan , Brendel Rolf
Published: July 2010

Due to an unfortunate conversion error during typesetting, Figure 1 of the Rapid Research Letter by Silke Steingrube et al., published in Phys. Status Solidi RRL 4, No. 3–4, 91–93 (2010), was reproduced with partly wrong labels (especially the assignment of curves in Fig. 1a, b). The correct Figure 1 is presented here. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Using Hidden Markov Model to detect rogue access points
Authors: Shivaraj Gayathri , Song Min , Shetty Sachin
Published: July 2010

One of the most challenging security concerns for network administrators is the presence of rogue access points (RAPs). The challenge is to detect and disable a RAP before it poses a serious security risk. In this paper, we propose a statistical based approach to detect RAPs using a Hidden Markov Model (HMM), which is applied to passively measure packet‐header data collected at a gateway router. The main idea is to process the sequence of packet traces in order to distinguish the normal packets from the abnormal ones. Our approach utilizes variations in packet inter‐arrival time to differentiate between authorized access points and RAPs. We used the inter‐arrival time of a packet as a distinguishing parameter because it varies drastically for a normal activity and an intrusive activity. We developed our HMM by analyzing Denial of Service (DoS) attacks of 802.11 based wireless local area networks. Our trained HMM can detect the presence of a RAP promptly within a second with extreme accuracy (very low false positive and false negative ratios are obtained). The success of our approach lies in the fact that it leverages knowledge about the behavior of the traffic characteristics of 802.11 based wireless local area networks and the properties of DoS attacks. Experiments were also performed to improve the accuracy of our HMM model. Our approach is scalable and non‐intrusive, requiring little deployment cost and effort, and is easy to manage and maintain. Copyright © 2010 John Wiley & Sons, Ltd.
Assignment of grouped exposure levels for trend estimation in a regression analysis of summarized data
Authors: Takahashi Kunihiko , Tango Toshiro
Published: July 2010

For performing regression analysis of summarized response data containing grouped intervals of exposure, many researchers use pre‐assigned doses such as the median values of each interval. However, the trend estimate is considerably sensitive to the choice of the assigned values. In this paper, we propose a method to assign the values to obtain a more accurate regression coefficient applying the likelihood approach. Numerical illustrations and comparisons through simulations showed that the proposed dose assignment can yield better estimates of trend in the regression analysis of two variants than that obtained by the conventional assignment methods such as those that use median values. In particular, for the data of a case–control study, the proposed dose improved the accuracy of the procedures such as that developed by Greenland and Longnecker (1992) compared with the conventional pre‐assigned dose. Copyright © 2010 John Wiley & Sons, Ltd.
Post BWT stages of the Burrows–Wheeler compression algorithm
Authors: Abel Jürgen
Published: July 2010

The lossless Burrows–Wheeler compression algorithm has received considerable attention over recent years for both its simplicity and effectiveness. It is based on a permutation of the input sequence—the Burrows–Wheeler transformation (BWT)—which groups symbols with a similar context close together. In the original version, this permutation was followed by a Move‐To‐Front transformation and a final entropy coding stage. Later versions used different algorithms, placed after the BWT, since the following stages have a significant influence on the compression rate. This paper describes different algorithms and improvements for these post BWT stages including a new context‐based approach. The results for compression rates are presented together with compression and decompression times on the Calgary corpus, the Canterbury corpus, the large Canterbury corpus and the Lukas 2D 16‐bit medical image corpus. Copyright © 2010 John Wiley & Sons, Ltd.