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Pronounced Differences (pronounced + difference)
Selected AbstractsAdvanced tilt correction from flow distortion effects on turbulent CO2 fluxes in complex environments using large eddy simulationTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 643 2009F. Griessbaum Abstract Measurement of the turbulent fluxes of gases, momentum and heat can be biased by obstacles such as buildings or instrument platforms distorting the flow of air to the flux instruments. Standard methods have long been used to account for non-horizontal mean flows. Here we demonstrate a novel approach to correct for the effects of flow distortion which combines numerical flow modelling with eddy covariance measurements of the fluxes. This approach applies a flow distortion correction to the data prior to the application of the standard planar-fit and double-rotation methods. This new direction-dependent flow correction allows the determination of the correct orthogonal wind vector components and hence the vertical turbulent fluxes. We applied the method to a 10 Hz dataset of 3D wind components, temperature, and the concentrations of carbon dioxide and water vapour, as measured on top of a military tower above the city of Münster in northwest Germany during spring and summer 2007. Significant differences appeared between the fluxes that were calculated with the standard rotation methods alone and those that underwent flow distortion correction prior to the application of the rotation methods. The highest deviations of 27% were obtained for the momentum flux. Pronounced differences of 15% and 8% were found for the diurnal net fluxes of carbon dioxide and water vapour, respectively. The flow distortion correction for the carbon dioxide fluxes yielded the same magnitude as the WPL (Webb,Pearman,Leuning) correction for density fluctuations. Copyright © 2009 Royal Meteorological Society [source] Influence of genotype and geography on shell shape and morphometric trait variation among North Atlantic blue mussel (Mytilus spp.) populationsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009JONATHAN P. A. GARDNER The influence of geography and genotype on shell shape (outline) and trait (morphometric) variation among North Atlantic blue mussels and their hybrids has been examined. Shape differences among reference taxa (Mytilus trossulus, Mytilus edulis and Mytilus galloprovincialis) were consistent with an association between taxon-specific genes and shape genes. Newfoundland M. edulis × M. trossulus populations and northern Quebec M. trossulus populations exhibited an uncoupling of taxon-specific genes from shape genes, whereas Nova Scotia M. trossulus populations and SW England M. edulis × M. galloprovincialis populations exhibited an association between taxon-specific genes and shape genes. We found no evidence of a geographic effect (NE versus NW Atlantic) for shape variation, indicating that the genotype effect is stronger than any geographic effect at macrogeographic scales. Pronounced differences were observed in trait variability consistent with an association between taxon-specific genes and trait genes in European populations, and trait divergence of New York M. edulis from all European mussels. Trait variability in mussels from Newfoundland, Nova Scotia and northern Quebec indicated an uncoupling of taxon genes from trait genes, whereas trait variability in SW England M. edulis × M. galloprovincialis populations was consistent with background genotype, indicating a strong association between taxon genes and trait genes. A pronounced macrogeographic split (NE versus NW Atlantic) regardless of taxonomy was observed, indicating that geography exerts a greater influence than genotype on trait variation at the macrogeographic scale. This is consistent with pronounced within-taxon genetic divergence, indicative of different selection regimes or more likely of different evolutionary histories of mussels on either side of the North Atlantic. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 875,897. [source] Quantitative analyses of the abundance and composition of ammonia-oxidizing bacteria and ammonia-oxidizing archaea of a Chinese upland red soil under long-term fertilization practicesENVIRONMENTAL MICROBIOLOGY, Issue 9 2007Ji-zheng He Summary The abundance and composition of soil ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) were investigated by using quantitative real-time polymerase chain reaction, cloning and sequencing approaches based on amoA genes. The soil, classified as agri-udic ferrosols with pH (H2O) ranging from 3.7 to 6.0, was sampled in summer and winter from long-term field experimental plots which had received 16 years continuous fertilization treatments, including fallow (CK0), control without fertilizers (CK) and those with combinations of fertilizer nitrogen (N), phosphorus (P) and potassium (K): N, NP, NK, PK, NPK and NPK plus organic manure (OM). Population sizes of AOB and AOA changed greatly in response to the different fertilization treatments. The NPK + OM treatment had the highest copy numbers of AOB and AOA amoA genes among the treatments that received mineral fertilizers, whereas the lowest copy numbers were recorded in the N treatment. Ammonia-oxidizing archaea were more abundant than AOB in all the corresponding treatments, with AOA to AOB ratios ranging from 1.02 to 12.36. Significant positive correlations were observed among the population sizes of AOB and AOA, soil pH and potential nitrification rates, indicating that both AOB and AOA played an important role in ammonia oxidation in the soil. Phylogenetic analyses of the amoA gene fragments showed that all AOB sequences from different treatments were affiliated with Nitrosospira or Nitrosospira- like species and grouped into cluster 3, and little difference in AOB community composition was recorded among different treatments. All AOA sequences fell within cluster S (soil origin) and cluster M (marine and sediment origin). Cluster M dominated exclusively in the N, NP, NK and PK treatments, indicating a pronounced difference in the community composition of AOA in response to the long-term fertilization treatments. These findings could be fundamental to improve our understanding of the importance of both AOB and AOA in the cycling of nitrogen and other nutrients in terrestrial ecosystems. [source] Mineralization of organic contaminants in sludge-soil mixturesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2001Bo Gejlsbjerg Abstract The mineralization of 14C-labeled linear alkylbenzene sulfonate (LAS), nonylphenol (NP), nonylphenol-di-ethoxylate (NP2EO), di-(2-ethylhexyl)phthalate (DEHP), pyrene, and 1,4-dichlorobenzene (DCB) was investigated in different sludge-soil mixtures and soils. Under aerobic conditions, the mineralization of LAS, NP, and NP2EO was between 50 and 81% of the added amounts after two months, while DEHP and pyrene were mineralized more slowly. The mineralization of the model chemicals was indirectly affected by the amount of sludge in the test mixtures. A higher content of sludge in the mixtures reduced the overall concentration of oxygen, which resulted in a decrease of the mineralization of several of the model chemicals. In sludge-soil mixtures with predominantly anaerobic conditions, the mineralization was slower for all of the chemicals with the exception of DEHP and DCB. The mineralization of DCB was enhanced in mixtures with a high sludge content. No pronounced difference in the mineralization of the model chemicals (except DEHP) was observed when the sludge was mixed with three different agricultural soils. [source] MDM2 SNP309 promoter polymorphism, an independent prognostic factor in chronic lymphocytic leukemiaEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 3 2010Kerstin Willander Abstract Background:, The single nucleotide polymorphism SNP309 with a change from T to G in the promoter region of the MDM2 gene is shown to increase the MDM2 protein levels and attenuate the p53 levels and associates with disease progression in several tumors. Objective:, In this study, the role of the polymorphism was investigated with regard to the clinical outcome in B-cell chronic lymphocytic leukemia (B-CLL). Patients:, A total of 210 patients with B-CLL were followed for up to 19 yr. Results:, The overall survival (OS) of patients with at least one G-allele was significantly shorter when compared with those with two T-alleles (P = 0.024) with a more pronounced difference in patients below the median age. Age at onset of B-CLL was similar irrespective of MDM2 status. The presence of a G-allele in combination with TP53 mutations or unmutated IgVH gene status resulted in an additive risk of death. Conclusion:, In this report, with a high proportion of B-CLL patients with an advanced Binet stage and with an unmutated IgVH gene, MDM2 SNP309 was found to be independently associated with OS. The survival difference was more pronounced in younger patients. [source] Monotonic and Cyclic Deformation Behaviour of the SiC Particle-Reinforced Aluminium Matrix Composite AMC225xe,ADVANCED ENGINEERING MATERIALS, Issue 4 2010Marek Smaga The monotonic and cyclic deformation behaviour of the aluminium matrix composite AMC225xe , i.e., the aerospace grade aluminium alloy AA 2124 reinforced with 25,vol.-% ultrafine SiC particles , is characterised in detail on the basis of mechanical stress,strain hysteresis curves as well as temperature and electrical resistance measurements. A pronounced difference in plastic strain response is observed between tension and compression under monotonic and cyclic loading. In fully reversed stress-controlled constant amplitude tests, negative plastic mean strains developed. The cyclic deformation behaviour of AMC225xe is characterised by pronounced initial cyclic hardening. The endurance limit is reliably estimated in continuous load increase tests. In particular, electrical resistance data are used as input parameters for fatigue life calculations analogous to the Basquin equation. Microstructural details are investigated by light and scanning electron microscopy. [source] Specific cleavage of the DNase-I binding loop dramatically decreases the thermal stability of actinFEBS JOURNAL, Issue 18 2010Anastasia V. Pivovarova Differential scanning calorimetry was used to investigate the thermal unfolding of actin specifically cleaved within the DNaseI-binding loop between residues Met47-Gly48 or Gly42-Val43 by two bacterial proteases, subtilisin or ECP32/grimelysin (ECP), respectively. The results obtained show that both cleavages strongly decreased the thermal stability of monomeric actin with either ATP or ADP as a bound nucleotide. An even more pronounced difference in the thermal stability between the cleaved and intact actin was observed when both actins were polymerized into filaments. Similar to intact F-actin, both cleaved F-actins were significantly stabilized by phalloidin and aluminum fluoride; however, in all cases, the thermal stability of the cleaved F-actins was much lower than that of intact F-actin, and the stability of ECP-cleaved F-actin was lower than that of subtilisin-cleaved F-actin. These results confirm that the DNaseI-binding loop is involved in the stabilization of the actin structure, both in monomers and in the filament subunits, and suggest that the thermal stability of actin depends, at least partially, on the conformation of the nucleotide-binding cleft. Moreover, an additional destabilization of the unstable cleaved actin upon ATP/ADP replacement provides experimental evidence for the highly dynamic actin structure that cannot be simply open or closed, but rather should be considered as being able to adopt multiple conformations. Structured digital abstract ,,MINT-7980274: Actin (uniprotkb:P68135) and Actin (uniprotkb:P68135) bind (MI:0407) by biophysical (MI:0013) [source] Ultrasonic velocities of North Sea chalk samples: influence of porosity, fluid content and textureGEOPHYSICAL PROSPECTING, Issue 4 2005Birte Røgen ABSTRACT We have studied 56 unfractured chalk samples of the Upper Cretaceous Tor Formation of the Dan, South Arne and Gorm Fields, Danish North Sea. The samples have porosities of between 14% and 45% and calcite content of over 95%. The ultrasonic compressional- and shear-wave velocities (VP and VS) for dry and water-saturated samples were measured at up to 75 bar confining hydrostatic pressure corresponding to effective stress in the reservoir. The porosity is the main control of the ultrasonic velocities and therefore of the elastic moduli. The elastic moduli are slightly higher for samples from the South Arne Field than from the Dan Field for identical porosities. This difference may be due to textural differences between the chalk at the two locations because we observe that large grains (i.e. filled microfossils and fossil fragments) that occur more frequently in samples from the Dan Field have a porosity-reducing effect and that samples rich in large grains have a relatively low porosity for a given P-wave modulus. The clay content in the samples is low and is mainly represented by either kaolinite or smectite; samples with smectite have a lower P-wave modulus than samples with kaolinite at equal porosity. We find that ultrasonic VP and VS of dry chalk samples can be satisfactorily estimated with Gassmann's relationships from data for water-saturated samples. A pronounced difference between the VP/VS ratios for dry and water-saturated chalk samples indicates promising results for seismic amplitude-versus-offset analyses. [source] Determination of intrathyroidal iodine by X-ray fluorescence analysis in 60- to 65-year olds living in an iodine-sufficient areaJOURNAL OF INTERNAL MEDICINE, Issue 1 2006M. MILAKOVIC Abstract. Objectives., X-ray fluorescence (XRF) is a non-invasive method for determining the iodine content of the thyroid gland in vivo. In spite of the obvious clinical value of such a method in situations of iodine deficiency or iodine overload, the method has not so far been widely used. The objective was to investigate the applicability of the XRF method in a larger number of subjects. Design and subjects., The study comprised 37 individuals, aged 60,65 years, who had spent their entire life with iodine supplementation through iodinated table salt. Individuals with (previous) thyroid disease were excluded. The individual thyroid function had previously been evaluated by measurements of thyroid-related hormones, thyroid volume and 131-Iodine (131I) uptake which indicated a sufficient iodine intake of the population in the area. Iodine in the right thyroid lobe in each subject was examined using XRF. Results., The mean thyroid iodine concentration was 0.4 mg mL,1, corresponding to a mean total iodine content of 5.2 mg (range 0.9,20.2). There was a pronounced difference between individuals. No correlation was found between iodine concentration and 131I uptake or thyroid volume. Neither was iodine content and 131I uptake correlated. Conclusions., In a population living under iodine-sufficient conditions, a large variation of iodine stored in the thyroid is compatible with euthyroidism. Determination of the iodine pool by XRF investigation is feasible in a clinical setting and the method offers a unique possibility to study the intrathyroidal iodine pool in subjects with thyroid disease. The low radiation dose enables the use of the method in pregnant women and also in young individuals. [source] HPLC of humic substances fractionated by Flow FFFJOURNAL OF SEPARATION SCIENCE, JSS, Issue 5 2003Maria-Anna Benincasa Abstract This communication reports a study of the effect of ionic strength and electrolyte composition on fractions, separately collected by flow FFF, of a mixture of humic substances. Reverse phase HPLC analysis of three early eluting fractions suggests that the components released by the column behave as organic acids. The baseline-resolved peaks of the first two fractions, subject to higher retention in solutions of lower pH and/or higher polarity, substantiate this suggestion. The fraction with larger components, as measured by flow FFF, also appears to contain acidic species. Their retention level, however, may not be accurately modulated by varying the mobile phase properties as these species are either totally retained in acidic phases or released before the void peak at pH , 4.2. Besides showing the effective separation achieved in the flow FFF channel, this study reveals the pronounced difference in the physicochemical properties of some components of a humic mixture even with very close particle size. [source] Density functional study of graphene overlayers on SiCPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2008Alexander Mattausch Abstract Despite the ongoing "graphene boom" of the last three years our understanding of epitaxial graphene grown on SiC substrate is only beginning to emerge. Along with experimental methods such as low energy electron diffraction (LEED), scanning tunneling microscopy (STM) and angle resolved photoemission spectroscopy (ARPES), ab initio calculations help to uncover the geometric and electronic structure of the graphene/SiC interface. In this chapter we describe the density-functional calculations we performed for single and double graphene layers on Si- and C-terminated 6H-SiC surfaces. Experimental data reveal a pronounced difference between the two surface terminations. On a Si-terminated surface the interface adopts a 6,3 × 6,3 unit cell whereas the C-face supports misoriented (turbostratic) graphene layers. It has been recently realized that, on the Si-face, the large commensurate cell is subdivided into patches of coherently matching to the substrate carbon atoms. In our calculations we assumed the "coherent match" geometry for the whole interface plane. This reduces the periodic unit to the ,3 × ,3R 30° cell but requires a substantial stretching of the graphene sheet. Although simplified, the model provides a qualitative picture of the bonding and of the interface electron energy spectrum. We find that the covalent bonding between the carbon layer and the substrate destroys the massless "relativistic" electron energy spectrum, the hallmark of a freestanding graphene. Hence the first carbon layer cannot be responsible for the graphene-type electron spectrum observed by ARPES and rather plays a role of a buffer between the substrate and the subsequent carbon sheets. The "true" graphene spectrum appears with the second carbon layer which exhibits a weak van der Waals bonding to the underlying structure. For Si-terminated substrate, we find that the Fermi level is pinned by the interface state at 0.45 eV above the graphene Dirac point, in agreement with experimental data. This renders the interface metallic. On the contrary, for a C-face the "coherent match" model predicts the Fermi level exactly at the Dirac point. However, this does not necessarily apply to the turbostratic graphene layers that normally grow on the C-terminated substrate. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Genotoxicity and physicochemical characteristics of traffic-related ambient particulate matterENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2005Theo M. de Kok Abstract Exposure to ambient particulate matter (PM) has been linked to several adverse health effects. Since vehicular traffic is a PM source of growing importance, we sampled total suspended particulate (TSP), PM10, and PM2.5 at six urban locations with pronounced differences in traffic intensity. The mutagenicity, DNA-adduct formation, and induction of oxidative DNA damage by the samples were studied as genotoxicological parameters, in relation to polycyclic aromatic hydrocarbon (PAH) levels, elemental composition, and radical-generating capacity (RGC) as chemical characteristics. We found pronounced differences in the genotoxicity and chemical characteristics of PM from the various locations, although we could not establish a correlation between traffic intensity and any of these characteristics for any of the PM size fractions. Therefore, the differences between locations may be due to local sources of PM, other than traffic. The concentration of total (carcinogenic) PAHs correlated positively with RGC, direct and S9-mediated mutagenicity, as well as the induction of DNA adducts and oxidative DNA damage. The interaction between total PAHs and transition metals correlated positively with DNA-adduct formation, particularly from the PM2.5 fraction. RGC was not associated with one specific PM size fraction, but mutagenicity and DNA reactivity after metabolic activation were relatively high in PM10 and PM2.5, when compared with TSP. We conclude that the toxicological characteristics of urban PM samples show pronounced differences, even when PM concentrations at the sample sites are comparable. This implies that emission reduction strategies that take chemical and toxicological characteristics of PM into account may be useful for reducing the health risks associated with PM exposure. Environ. Mol. Mutagen., 2005. © 2005 Wiley-Liss, Inc. [source] Marine diatom species harbour distinct bacterial communitiesENVIRONMENTAL MICROBIOLOGY, Issue 6 2005Hans-Peter Grossart Summary We examined bacterial dynamics in batch cultures of two axenic marine diatoms (Thalassiosira rotula and Skeletonema costatum). The axenic diatoms were inoculated with natural bacterial assemblages and monitored by 4,6-diamidino-2-phenolindole (DAPI) counts, denaturing gradient gel electrophoresis (DGGE) with subsequent analysis of excised, sequenced 16S rRNA gene fragments, and fluorescence in situ hybridization (FISH) with group-specific 16S rRNA oligonucleotide probes. Our results show that algal growth exhibited pronounced differences in axenic treatments and when bacteria were present. Bacterial abundance and community structure greatly depended on species, growth and physiological status of even closely related algae. Free-living and phytoplankton-associated bacteria were very different from each other and were dominated by distinct phylogenetic groups. The diatom-associated bacteria mainly belonged to the Flavobacteria,Sphingobacteria group of the Bacteroidetes phylum whereas free-living bacteria, which were rather similar in both cultures, comprised mainly of members of the Roseobacter,group ,of ,,- Proteobacteria. ,Presence and disappearance of specific bacteria during algal growth indicated pronounced differences in environmental conditions over time and selection of bacteria highly adapted to the changing conditions. Tight interactions between marine bacteria and diatoms appear to be important for the decomposition of organic matter and nutrient cycling in the sea. [source] Feeding by short-snouted weevils on seedlings of seven tree species planted beneath Norway spruce at differing stand densitiesAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2009M. Löf Abstract 1,Short-snouted weevils, including Strophosoma spp. and related species, may damage tree seedlings. We investigated the damage caused by these weevils feeding on seedlings of seven tree species planted in clear-cuts and under shelterwoods with three densities (control, dense, and sparse). 2,There were no pronounced differences in damage caused by short-snouted weevils in the various shelterwood densities. Most feeding occurred in the clear-cuts during the first year, whereas more seedlings were damaged in the shelterwoods of all densities in the second year. In the third year, virtually no feeding occurred in either the clear-cuts or shelterwoods. We cannot explain this pattern of damage, but a fallow period of 2 years seems to prevent short-snouted weevil damage. 3,We determined the general feeding preferences for short-snouted weevils to be cherry, lime > beech, oak, spruce > maple, ash. However, although Strophosoma mellanogrammum [Correction added after online publication 8 December 2008: Strophosoma melanogrammum corrected to Strophosoma mellanogrammum] was observed feeding on seedlings, no full short-snouted weevil inventory was conducted, so caution must be exercised when drawing conclusions from this study regarding weevil damage patterns and feeding preferences. 4,Short-snouted weevils can sometimes occur in large numbers and may destroy entire reforestation projects, but in our study their influence on seedling growth and survival was minor. [source] A cognitive load approach to lie detectionJOURNAL OF INVESTIGATIVE PSYCHOLOGY AND OFFENDER PROFILING, Issue 1-2 2008Aldert Vrij Abstract We present two lie detection approaches based on cognitive theory. The first approach, ,measuring cognitive load', assumes that the mere act of lying generates observable signs of cognitive load. This is the traditional cognitive lie detection approach formulated by Zuckerman, DePaulo, & Rosenthal (1981). The second approach, ,imposing cognitive load', was developed by us (Vrij, Fisher, Mann, & Leal, 2006) and goes one step further. Here, the lie detector attempts to actively increase the differences between lying and truth telling by introducing mentally taxing interventions. We assume that people require more cognitive resources when they lie than when they tell the truth to produce their statements, and therefore will have fewer cognitive resources left over to address these mentally taxing interventions when they lie than when they tell the truth. This should result in more pronounced differences between lying and truth telling in terms of displaying stronger signs of cognitive load. We provide empirical support for this approach: Observers can discriminate better between lying and truth telling when interviewers actively impose mentally taxing interventions. Copyright © 2008 John Wiley & Sons, Ltd. [source] Event-Related fMRI of Inhibitory Control in the Predominantly Inattentive and Combined Subtypes of ADHDJOURNAL OF NEUROIMAGING, Issue 3 2009Mary V. Solanto PhD ABSTRACT BACKGROUND AND PURPOSE To examine the neurophysiological basis for the pronounced differences in hyperactivity and impulsiveness that distinguish the predominantly inattentive type of attention-deficit/hyperactivity disorder (ADHD-PI) from the combined type of the disorder (ADHD-C). METHODS Event-related brain responses to a go/no-go test of inhibitory control were measured with functional magnetic resonance imaging (fMRI) in 11 children with ADHD-C and 9 children with ADHD-PI, aged 7 to 13 years, who were matched for age, sex, and intelligence. RESULTS There were no significant group differences in task performance. Children with ADHD-C and ADHD-PI activated overlapping regions of right inferior frontal gyrus, right superior temporal lobe, and left inferior parietal lobe during inhibitory control. However, the magnitude of the activation in the temporal and parietal regions, as well as in the bilateral middle frontal gyrus, was greater in children with ADHD-PI than those with ADHD-C. Conversely, children with ADHD-C activated bilateral medial occipital lobe to a greater extent than children with ADHD-PI. CONCLUSIONS The results provide preliminary evidence that phenotypic differences between the ADHD-C and ADHD-PI subtypes are associated with differential activation of regions that have previously been implicated in the pathophysiology of ADHD and are thought to mediate executive and attentional processes. [source] Alkynyl Ethers of Glucans: Substituent Distribution in Propargyl-, Pentynyl- and Hexynyldextrans and -amyloses and Support for Silver Nanoparticle Formation,MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2010M. Nazir Tahir Abstract Alkynyldextrans with a DS in the range 0.1,1.67 have been prepared as reactive intermediates for further polymer-analogous functionalisation. DS and substituent distribution were determined by GLC and GLCMS after hydrolysis and acetylation, or methanolysis and trimethylsilylation. Reactivity was in the order O-2,>,O-4,,,O-3 with pronounced differences in the distinct patterns for propargyl ethers and its higher homologous. A large deviation from a random substituent distribution was observed. Propargyldextrans were not stable during long-time storage in the solid state, while terminal pentynyl and hexynyl ethers are. Pentynyldextrans showed structure formation of various geometries. They bound silver efficiently, yielding silver nanoparticles by reduction. [source] QSAR of Human Steroid 5,-Reductase Inhibitors: Where are the differences between isoenzyme type 1 and 2?MOLECULAR INFORMATICS, Issue 6 2004Michael Abstract Quantitative Structure Activity Relationships have been established for inhibitors of human steroid 5,-reductase including 6-azasteroids and non-steroidal compounds. From the applied descriptors, those related to the molecular geometry, electronic properties, and the electrostatic surface were derived from semi-empirical AM1 calculations. A chemical reaction as part of the inhibitory action is indicated by the presence of the ionization potential in the descriptor space. Strong similarities between the variables for the prediction of the binding affinity to the type 1 and IC50 values for the type 2 isoform of the 5,-reductase were observed. The most pronounced differences in the linear regression QSAR equations were found for the descriptors accounting for the hydrogen-bonding interaction, suggesting a different hydrogen-bonding pattern in the binding pocket of both isoforms. Furthermore, the topological indices together with the surface related descriptors point towards a lower content of aromatic amino acids in the binding site of the type 2 isoenzyme. Consequences for the design of new inhibitors are discussed. [source] Impact of traveling phonon wave packets on the optical response of quantum dotsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2009J. Huneke Abstract The influence of phonon wave packets created by the optical excitation of a quantum dot (QD) structure on four-wave-mixing (FWM) signals is analyzed theoretically. Two different structures are compared: a single QD in a half-space geometry located close to the surface, where the emitted phonon wave packet after reflection at the surface reenters the QD and a pair of QDs in an infinite medium, where the phonon wave packet created in one QD travels across the other QD. Although the strain fields are very similar pronounced differences in the FWM polarizations are found. In the single QD system we observe clear signatures of the reflected wave packet in the FWM signal at positive delay times, which can also be observed in the time-integrated FWM signal from an inhomogeneously broadened ensemble of such QDs. In the two QD case no signatures of the traveling wave packet are seen in the signal at positive delays and, consequently, in the ensemble signal. However, they are clearly seen in the FWM signal at negative delay times. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Exchanging the active site between phytases for altering the functional properties of the enzymePROTEIN SCIENCE, Issue 10 2000Martin Lehmann Abstract By using a novel consensus approach, we have previously managed to generate a fully synthetic phytase, consensus phytase-1, that was 15-26 °C more thermostable than the parent fungal phytases used in its design (Lehmann et al., 2000). We now sought to use the backbone of consensus phytase-1 and to modify its catalytic properties. This was done by replacing a considerable part of the active site (i.e., all the divergent residues) with the corresponding residues of Aspergillus niger NRRL 3135 phytase, which displays pronounced differences in specific activity, substrate specificity, and pH-activity profile. For the new protein termed consensus phytase-7, a major,although not complete,shift in catalytic properties was observed, demonstrating that rational transfer of favorable catalytic properties from one phytase to another is possible by using this approach. Although the exchange of the active site was associated with a 7.6 °C decrease in unfolding temperature (Tm) as measured by differential scanning calorimetry, consensus phytase-7 still was >7 °C more thermostable than all wild-type ascomycete phytases known to date. Thus, combination of the consensus approach with the selection of a "preferred" active site allows the design of a thermostabilized variant of an enzyme family of interest that (most closely) matches the most favorable catalytic properties found among its family members. [source] Multivariate analysis of protein profiles of metal hyperaccumulator Thlaspi caerulescens accessionsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 12 2006Marjo H. Tuomainen Abstract Thlaspi caerulescens is increasingly acknowledged as one of the best models for studying metal hyperaccumulation in plants. In order to study the mechanisms underlying metal hyperaccumulation, we used proteomic profiling to identify differences in protein intensities among three T.,caerulescens accessions with pronounced differences in tolerance, uptake and root to shoot translocation of Zn and Cd. Proteins were separated using two-dimensional electrophoresis and stained with SYPRO Orange. Intensity values and quality scores were obtained for each spot by using PDQuest software. Principal component analysis was used to test the separation of the protein profiles of the three plant accessions at various metal exposures, and to detect groups of proteins responsible for the differences. Spot sets representing individual proteins were analysed with the analysis of variance and non-parametric Kruskal-Wallis test. Clearest differences were seen among the Thlaspi accessions, while the effects of metal exposures were less pronounced. The 48,tentatively identified spots represent core metabolic functions (e.g. photosynthesis, nitrogen assimilation, carbohydrate metabolism) as well as putative signalling and regulatory functions. The possible roles of some of the proteins in heavy metal accumulation and tolerance are discussed. [source] Mineralogical And Chemical Investigations Of Bloomery Slags From Prehistoric (8th Century Bc To 4th Century Ad) Iron Production Sites In Upper And Lower Lusatia, GermanyARCHAEOMETRY, Issue 2 2001R. B. Heimann More than 400 fayalitic bloomery slags from prehistoric iron production sites in Upper and Lower Lusatia, eastern Germany, as well as bog iron ore samples and intermediary samples of the smelting process, were analysed by chemical and mineralogical techniques. While the precursor bog iron ores exploited in the two regions under investigation were very similar in composition, consisting of low-manganese/low-barium as well as high-manganese/high-barium types of ore, pronounced differences in slag composition were detected. Slags from 17 investigated sites in Upper Lusatia showed average P2O5 contents between 1 and 3 mass%, whereas slags from 15 investigated sites in Lower Lusatia were generally much richer in phosphorus, reaching values as high as 7 mass% P2O5. Since a reasonable correlation exists between calcium and phosphorus contents in the slags of the latter sites, it is conjectured that deliberate addition of CaO to the ore/charcoal charge of the bloomery furnace may have taken place in order to fix the phosphorus in the slags effectively. In many samples, this conjecture is being supported by the detection of a slag mineral Ca,Fe phosphate Ca9,xFe1+x(PO4)7 that presumably crystallized from a residual phosphorus-rich melt and shows a cotectic relationship to both Ca-rich fayalite and wustite, as well as to members of the solid solution series magnetite,hercynite. [source] | |||||||||||||||||||||||||