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Extreme Conditions (extreme + condition)
Selected AbstractsAssociating Borate and Silicate Chemistry by Extreme Conditions: High-Pressure Synthesis, Crystal Structure, and Properties of the New Borates Ln3B5O12 (Ln: Er,Lu).CHEMINFORM, Issue 32 2005Holger Emme Abstract For Abstract see ChemInform Abstract in Full Text. [source] Rapid categorization of achromatic natural scenes: how robust at very low contrasts?EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2005Marc J.-M. Abstract The human visual system is remarkably good at categorizing objects even in challenging visual conditions. Here we specifically assessed the robustness of the visual system in the face of large contrast variations in a high-level categorization task using natural images. Human subjects performed a go/no-go animal/nonanimal categorization task with briefly flashed grey level images. Performance was analysed for a large range of contrast conditions randomly presented to the subjects and varying from normal to 3% of initial contrast. Accuracy was very robust and subjects were performing well above chance level (, 70% correct) with only 10,12% of initial contrast. Accuracy decreased with contrast reduction but reached chance level only in the most extreme condition (3% of initial contrast). Conversely, the maximal increase in mean reaction time was ,,60 ms (at 8% of initial contrast); it then remained stable with further contrast reductions. Associated ERPs recorded on correct target and distractor trials showed a clear differential effect whose amplitude and peak latency were correlated respectively with task accuracy and mean reaction times. These data show the strong robustness of the visual system in object categorization at very low contrast. They suggest that magnocellular information could play a role in ventral stream visual functions such as object recognition. Performance may rely on early object representations which lack the details provided subsequently by the parvocellular system but contain enough information to reach decision in the categorization task. [source] Naltrexone: report of lack of hepatotoxicity in acute viral hepatitis, with a review of the literatureADDICTION BIOLOGY, Issue 1 2004Colin Brewer Many clinicians appear to be concerned about the potential hepatotoxicity of the opiate antagonist naltrexone (NTX) and this may be one reason why it is not used more widely in treating both heroin and alcohol abusers. Some much-quoted early studies noted abnormalities in liver function tests (LFTs) in very obese patients taking high doses, although there was no evidence of clinically significant liver dysfunction. These concerns may be reinforced by advice in the UK product information sheet to perform LFTs before and during treatment, by high infection rates with hepatitis C virus (HCV) among injecting heroin addicts and by the frequency of abnormal LFTs in alcohol abusers. We describe a heroin abuser in whom clinical and laboratory manifestations of acute hepatitis B and C appeared a few days after the insertion of a subcutaneous naltrexone implant. A decision was made not to remove the implant but the hepatitis resolved completely and uneventfully well within the normal time-scale. A review of the literature indicates that even when given at much higher doses than are needed for treating heroin or alcohol abusers, there is no evidence that NTX causes clinically significant liver disease or exacerbates, even at high doses, serious pre-existing liver disease. During the past decade, NTX has been shown to be safe and effective in the treatment of pruritus associated with severe jaundice caused by severe and sometimes life-threatening cirrhosis and other liver diseases. Its safety, even in these extreme conditions, is particularly reassuring. We suggest that it may be more appropriate and economical to advise patients to report promptly any suspected side effects than to perform regular LFTs, which may be misleading. [source] Microstructure and Properties of an HfB2 -SiC Composite for Ultra High Temperature Applications,ADVANCED ENGINEERING MATERIALS, Issue 5 2004F. Monteverde An ultra-high-temperature ceramic (UHTC) based on HfB2 was produced. The microstructure consisted of fine and regular diboride grains (2 ,m average size), with SiC particulate distributed intergranularly, not rarely in clustered formation, and low levels of secondary phases were identified. The resulting thermo-mechanical properties proved interesting results for microhardness and fracture toughness. The microstructural alteration experienced within the explored temperature range renders the material unsuitable for service in extreme conditions of temperature and pressure. [source] The oxidation process of Antarctic fish hemoglobinsFEBS JOURNAL, Issue 9 2004Luigi Vitagliano Analysis of the molecular properties of proteins extracted from organisms living under extreme conditions often highlights peculiar features. We investigated by UV-visible spectroscopy and X-ray crystallography the oxidation process, promoted by air or ferricyanide, of five hemoglobins extracted from Antarctic fishes (Notothenioidei). Spectroscopic analysis revealed that these hemoglobins share a common oxidation pathway, which shows striking differences from the oxidation processes of hemoglobins from other vertebrates. Indeed, simple exposure of these hemoglobins to air leads to the formation of a significant amount of the low-spin hexacoordinated form, denoted hemichrome. This hemichrome form, which is detected under a variety of experimental conditions, can be reversibly transformed to either carbomonoxy or deoxygenated forms with reducing agents. Interestingly, the spectra of the fully oxidized species, obtained by treating the protein with ferricyanide, show the simultaneous presence of peaks corresponding to different hexacoordinated states, the aquomet and the hemichrome. In order to assign the heme region state of the , and , chains, the air-oxidized and ferricyanide-oxidized forms of Trematomus bernacchii hemoglobin were crystallized. Crystallographic analysis revealed that these forms correspond to an ,(aquomet)-,(bishistidyl-hemichrome) state. This demonstrates that the , and , chains of Antarctic fish hemoglobins follow very different oxidation pathways. As found for Trematomus newnesi hemoglobin in a partial hemichrome state [Riccio, A., Vitagliano, L., di Prisco, G., Zagari, A. & Mazzarella, L. (2002) Proc. Natl Acad. Sci. USA99, 9801,9806], the quaternary structures of these ,(aquomet)-,(bishistidyl-hemichrome) forms are intermediate between the physiological R and T hemoglobin states. Together, these structures provide information on the general features of this intermediate state. [source] Lipid biomarkers, pigments and cyanobacterial diversity of microbial mats across intertidal flats of the arid coast of the Arabian Gulf (Abu Dhabi, UAE)FEMS MICROBIOLOGY ECOLOGY, Issue 3 2008Raeid M.M. Abed Abstract Variations in morphology, fatty acids, pigments and cyanobacterial community composition were studied in microbial mats across intertidal flats of the arid Arabian Gulf coast. These mats experience combined extreme conditions of salinity, temperature, UV radiation and desiccation depending on their tidal position. Different mat forms were observed depending on the topology of the coast and location. The mats contained 63 fatty acids in different proportions. The increased amounts of unsaturated fatty acids (12,39%) and the trans/cis ratio (0.6,1.6%) of the cyanobacterial fatty acid n- 18:1,9 in the higher tidal mats suggested an adaptation of the mat microorganisms to environmental stress. Chlorophyll a concentrations suggested lower cyanobacterial abundance in the higher than in the lower intertidal mats. Scytonemin concentrations were dependent on the increase in solar irradiation, salinity and desiccation. The mats showed richness in cyanobacterial species, with Microcoleus chthonoplastes and Lyngbya aestuarii morphotypes as the dominant cyanobacteria. Denaturing gradient gel electrophoresis patterns suggested shifts in the cyanobacterial community dependent on drainage efficiency and salinity from lower to higher tidal zones. We conclude that the topology of the coast and the variable extreme environmental conditions across the tidal flat determine the distribution of microbial mats as well as the presence or absence of different microorganisms. [source] Designing Polymers to Enable Nanoscale Thermomechanical Data StorageADVANCED FUNCTIONAL MATERIALS, Issue 8 2010B. Gotsmann Abstract Nanomechanics has been slow in entering nanotechnology because of extreme conditions resulting from scaling. This is an issue in particular for polymers, although widely used in macroscale applications. Highly repetitive nanoscale deformation cycling in combination with excellent shape retention and thermal stability is demonstrated. While generic principles described are pertinent to a range of applications, this demonstration is made on the example of polymer media in high-density data storage. The information, represented as indents, is written and erased using a heated tip. A high-performance polymer with a flexible aryletherketone backbone is designed with phenylethynyl crosslink chemistry. After optimization of crosslink density and topology, unprecedented performance is achieved in all relevant metrics. Demonstrations of endurance and retention are performed at 1 Tb in,2 density, showing 108 write cycles using the same tip, 103 erase cycles and 3,×,105 read cycles of the media, and extrapolated to 10 years of retention at 85,°C. [source] High Plasticity and Substantial Deformation in Nanocrystalline NiFe Alloys Under Dynamic LoadingADVANCED MATERIALS, Issue 48 2009Sheng Cheng A nanocrystalline (NC) NiFe alloy is presented, in which both highly improved plasticity and strength are achieved by the dynamic-loading-induced deformation mechanisms of de-twinning (that is, reduction of twin density) and significant grain coarsening (see figure). This work highlights potential ingenious avenues to exploit the superior behavior of NC materials under extreme conditions. [source] Parents and infants in changing cultural context: Immigration, trauma, and riskINFANT MENTAL HEALTH JOURNAL, Issue 3 2003Marie Rose Moro "Entre les bibliothèques et les bébés en détresse, il y a un grand fossé" (S. Fraiberg). "Between library and at-risk infants themselves lies a great gulf" (Fraiberg, 1999, p. 416). Whether they are African or Asian, children of immigrant families live in at-risk situations where they may be exposed to serious trauma. Immigrant families often live in extreme conditions. Although research describes these conditions, the field of intervention remains weak. How many times have I heard that work among these families does not address treatment, but only basic needs, noting that the families are preoccupied with survival,where to find food, where to sleep, where to bury their dead. Yet, the psychological care of immigrant children and families has much to teach us. In this article I will describe work that attempts to bridge the gulf that Fraiberg referred to by sharing what I have learned regarding immigrant families with infants. ©2003 Michigan Association for Infant Mental Health. [source] Magnetic Materials: X-Ray Magnetic Circular Dichroism Picks out Single-Molecule Magnets Suitable for Nanodevices (Adv. Mater.ADVANCED MATERIALS, Issue 2 20092/2009) The surface sensitivity of X-ray magnetic circular dichroism in extreme conditions has been exploited to investigate the first layers of bulk single-molecule magnets (SMMs), as reported by Roberta Sessoli and co-workers on p. 167. Striking differences have emerged between two classes of SMM having different structural constraints, thus highlighting the importance of molecular design in the realization of molecular spintronic devices. [source] X-Ray Magnetic Circular Dichroism Picks out Single-Molecule Magnets Suitable for NanodevicesADVANCED MATERIALS, Issue 2 2009Matteo Mannini The surface sensitivity of X-ray Magnetic Circular Dichroism in extreme conditions is exploited to investigate the first layers of bulk single-molecule magnets (SMM). Striking differences emerge between two classes of SMM with different structural constraints, thus highlighting the importance of molecular design in the realization of molecular spintronic devices [source] Rigid, Self-Assembled Hydrogel Composed of a Modified Aromatic Dipeptide,ADVANCED MATERIALS, Issue 11 2006A. Mahler A simple dipeptide self-assembles into a biocompatible hydrogel (see figure and inside cover). This novel biomaterial is extremely simple to prepare and has a remarkable rigidity. It is very stable under extreme conditions, can be injected, and can be shaped according to the vessel it has been assembled in. The hydrogel allows a wide variety of possible biomedical applications including tissue engineering, axonal regeneration, and controlled drug release. [source] Lack of Interaction between Extreme High-Temperature Events at Vegetative and Reproductive Growth Stages in WheatJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2003B. Wollenweber Abstract Increased climatic variability and more frequent episodes of extreme conditions may result in crops being exposed to more than one extreme temperature event in a single growing season and could decrease crop yields to the same extent as changes in mean temperature. The developmental stage of the crop exposed to increased temperatures will determine the severity of possible damage experienced by the plant. It is not known whether or not the damaging effects of heat episodes occurring at different phenological stages are additive. In the present study, the interaction of high-temperature events applied at the stages of double ridges and anthesis in Triticum aestivum (L.) cv. Chablis was investigated. Biomass accumulation of control plants and that of plants experiencing high temperatures during the double-ridge stage were similar and were reduced by 40 % when plants were subjected to a heat event at anthesis. Grain number on the main and side tillers declined by 41 %, and individual grain weight declined by 45 % with heat stress applied at the double-ridge stage and anthesis or at anthesis alone. The harvest index was reduced from 0.53 to 0.33. Nitrogen contents in leaves were reduced by 10 % at the double-ridge stage and by 25 % at anthesis. The maximum rates of CO2 assimilation increased with heat stress at the double-ridge stage and higher rates were maintained throughout the growing season. The results clearly indicate that an extreme heat event at the double-ridge stage does not affect subsequent growth or the response of wheat to heat stress at anthesis. [source] Confocal imaging of chromatographic fouling under flow conditionsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2007Sun Chau Siu Abstract BACKGROUND: The fouling impact of selected fouling species was assessed by utilising confocal scanning laser microscopy (CSLM) to image a packed chromatographic bed during operation. A custom-made flow cell was packed with Q Sepharose FF and loaded with partially clarified E. coli homogenate. Selective, multicoloured fluorescent dyes were used to label a bovine serum albumin (BSA) test protein (Cy5.5), dsDNA (PicoGreen) and host cell proteins (HCPs) (Cy3). The fouling caused by the various fluorescently labelled components was visualised as a result of the fluorescence emitted by the PicoGreen-labelled dsDNA and the Cy3-labelled protein in the foulant stream, and by testing the adsorptive capacity of a test protein (BSA) onto the resin prior to and post-fouling as well as following the application of a common CIP procedure. RESULTS: Values for the effective diffusivity of BSA (De) were derived from the confocal images and the fouling impact was assessed by comparing De values obtained from different fouling scenarios. Under the most extreme conditions examined, fouling caused a 20% reduction in capacity compared to a fresh bed. BSA diffusivity did not appear to be affected by the fouling conditions studied. Sequential CIP using 15 CVs of 1 mol L,1 NaCl then 15 CVs of 1 mol L,1 NaOH was shown to be effective in removing nucleic acids and HCPs. Subsequent BSA adsorption showed that the CIP regime successfully restored the column capacity to its original value. In contrast, 15 CVs of 1 mol L,1 NaCl were ineffective in removing dsDNA but substantially removed HCPs. CONCLUSION: CSLM was demonstrated to be a useful tool for visualising fouling mechanisms. Comparing the results obtained by this technique using different modes of chromatographic operation provided insights into the fouling characteristics of finite baths versus packed beds. Copyright © 2007 Society of Chemical Industry [source] Preface to the special issue on Raman spectroscopy under extreme conditionsJOURNAL OF RAMAN SPECTROSCOPY, Issue 7-8 2003Dr Guy Lucazeau No abstract is available for this article. [source] Energy-dispersive X-ray absorption spectroscopy at LNLS: investigation on strongly correlated metal oxidesJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2010Júlio C. Cezar An energy-dispersive X-ray absorption spectroscopy beamline mainly dedicated to X-ray magnetic circular dichroism (XMCD) and material science under extreme conditions has been implemented in a bending-magnet port at the Brazilian Synchrotron Light Laboratory. Here the beamline technical characteristics are described, including the most important aspects of the mechanics, optical elements and detection set-up. The beamline performance is then illustrated through two case studies on strongly correlated transition metal oxides: an XMCD insight into the modifications of the magnetic properties of Cr-doped manganites and the structural deformation in nickel perovskites under high applied pressure. [source] Achievements in high-pressure science at the high-brilliance energy-dispersive X-ray absorption spectrometer of ESRF, ID24JOURNAL OF SYNCHROTRON RADIATION, Issue 6 2009Giuliana Aquilanti Although the idea of an X-ray absorption spectrometer in dispersive geometry was initially conceived for the study of transient phenomena, the instrument at the European Synchrotron Radiation facility has been increasingly exploited for studies at extreme conditions of pressure using diamond anvil cells. The main results of investigations at high pressure obtained at beamline ID24 are reviewed. These concern not only fundamental topics, such as the local and the electronic structure as well as the magnetic properties of matter, but also geological relevant questions such as the behaviour of Fe in the main components of the Earth's interior. [source] ID20: a beamline for magnetic and resonant X-ray scattering investigations under extreme conditionsJOURNAL OF SYNCHROTRON RADIATION, Issue 4 2007L. Paolasini A new experimental station at ESRF beamline ID20 is presented which allows magnetic and resonant X-ray scattering experiments in the energy range 3,25,keV to be performed under extreme conditions. High magnetic field up to 10,T, high pressure up to 30,kbar combined with low temperatures down to 1.5,K are available and experiments can be performed at the M -edges of actinide elements, L -edges of lanthanides and K -edges of transition metals. [source] Adaptation of the antioxidant defence system in hydrothermal-vent mussels (Bathymodiolus azoricus) transplanted between two Mid-Atlantic Ridge sitesMARINE ECOLOGY, Issue 1 2007Rui Company Abstract The vent mussel Bathymodiolus azoricus is the dominant member of the Northern Mid-Atlantic Ridge (MAR) hydrothermal megafauna, and lives in an environment characterized by temporal and spatial variations in the levels of heavy metals, methane and hydrogen sulphide, substances which are known to increase reactive oxygen species levels in the tissues of exposed organisms. To evaluate the effects of two contrasting hydrothermal environments on the antioxidant defence system of this vent mussel species, a 2-week transplant experiment was carried out involving mussels collected from the relatively deep (2300 m), and chemical rich, Rainbow vent field. These were transplanted to the shallower (1700 m), and relatively less toxic, Lucky Strike vent field. To achieve this objective, levels of superoxide dismutase, catalase (CAT), total glutathione peroxidase (GPx), selenium-dependent glutathione peroxidase and lipid peroxidation (LPO) were measured in the gills and mantle tissues of resident and transplant mussels before and after the transplant experiment. With the exception of CAT, the gills of the transplanted mussels had significantly higher antioxidant enzyme activity compared with the basal levels in the donor (Rainbow) and recipient (Lucky Strike) populations; whereas the antioxidant enzyme levels in the mantle tissues of the transplants reflected the baseline levels of activity in the native Lucky Strike mussels after 2 weeks. In contrast, LPO levels were significantly higher in both tissue types in the transplants than in either the source or the recipient populations, which suggested a response to hydrostatic pressure change (note, the transplant animals were brought to the surface for transportation between the two vent fields). The fact that the Rainbow mussels survived the transplant experience indicates that B. azoricus has a very robust constitution, which enables it to cope behaviourally, physiologically and genetically with the extreme conditions found in its naturally contaminated deep-sea environment. [source] Laser-based in situ techniques: Novel methods for generating extreme conditions in TEM samples,MICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2009Mitra L. Taheri Abstract The dynamic transmission electron microscope (DTEM) is introduced as a novel tool for in situ processing of materials. Examples of various types of dynamic studies outline the advantages and differences of laser-based heating in the DTEM in comparison to conventional (resistive) heating in situ TEM methods. We demonstrate various unique capabilities of the drive laser, namely, in situ processing of nanoscale materials, rapid and high temperature phase transformations, and controlled thermal activation of materials. These experiments would otherwise be impossible without the use of the DTEM drive laser. Thus, the potential of the DTEM as a new technique to process and characterize the growth of a myriad of micro and nanostructures is demonstrated. Microsc. Res. Tech., 2009. Published 2009 Wiley-Liss, Inc. [source] Magnetar oscillations pose challenges for strange starsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2007Anna L. Watts ABSTRACT Compact relativistic stars allow us to study the nature of matter under extreme conditions, probing regions of parameter space that are otherwise inaccessible. Nuclear theory in this regime is not well constrained: one key issue is whether neutron stars are in fact composed primarily of strange quark matter. Distinguishing the two possibilities, however, has been difficult. The recent detection of seismic vibrations in the aftermath of giant flares from two magnetars (highly magnetized compact stars) is a major breakthrough. The oscillations excited seem likely to involve the stellar crust, the properties of which differ dramatically for strange stars. We show that the resulting mode frequencies cannot be reconciled with the observations for reasonable magnetar parameters. Ruling out strange star models would place a strong constraint on models of dense quark matter. [source] Gene expression profiling of Dunaliella sp. acclimated to different salinitiesPHYCOLOGICAL RESEARCH, Issue 1 2010Minjung Kim SUMMARY To investigate which genes may be important for growth under extreme conditions such as very low or high salinities, a survey of the Dunaliella sp. transcriptome was performed with a cDNA microarray which had been generated previously representing 778 expressed sequence tags. The comparative microarray analysis indicated that 142 genes differed in expression levels by more than twofold in cells grown at extreme salinities (0.08 M and 4.5 M NaCl) when compared with cells grown at intermediate salinity (1.5 M NaCl). Of these genes, 28 had increased expression and 57 were suppressed in cells grown at low salinity. In cells grown at high salinity, 43 genes showed increased expression and 69 genes showed suppressed expression. However, we did observe a large overlap in the expression of extreme salinity-responsive genes based on Venn diagram analysis, which found 55 genes that responded to both of the two extreme salinity conditions. Further, we found that several genes had similar expression levels under low and high salinities, including some general stress response genes that were upregulated in both extreme salinity conditions. For confirmation of the validity of the cDNA microarray analysis, expression of several genes was independently confirmed by the use of gene-specific primers and real-time polymerase chain reaction. The present study is the first large-scale comparative survey of the transcriptome from the microalga Dunaliella sp. acclimated to extreme salinities, thus providing a platform for further functional investigation of differentially expressed genes in Dunaliella. [source] Prediction of electronic, structural and elastic properties of the hardest oxide: TiO2PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2009M. A. Caravaca Abstract This work combines the theory of elasticity with first principles quantum mechanic calculations to predict the electronic, structural and elastic properties: elastic constants, bulk moduli of the TiO2 (Titania) in the Pnma phase. Band-structure shows a direct gap in , which increases its value under hydrostatic pressure. It has two regimes: in the range 0,50 GPa the band-gap has a negative second pressure derivative and changes its sign in the range 50,100 GPa. The band gap becomes indirect at pressures above 150 GPa. This phase improves its mechanical stability and insulator properties under extreme conditions of hydrostatic pressures. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Simulation and validation of resin flow during manufacturing of composite panels containing embedded impermeable inserts with the VARTM processPOLYMER COMPOSITES, Issue 4 2007Jeffrey M. Lawrence Modern composite materials are becoming more and more advanced as engineers are better able to take advantage of their properties. In addition to their lighter weight and net-shape manufacturing, current interest is to make these materials multifunctional. This may require one to insert various objects into the composite to achieve a variety of different goals. It is important to understand how these embedded objects will affect both the manufacturing and the structural integrity of the component. In this work, the effects of impermeable embedded inserts on the infusion stage of vacuum-assisted resin transfer molding (VARTM) will be explored. In VARTM, one places a distribution media on top of the preform to aid the filling as the resin will first fill the face of the preform in contact with the distribution media and will then infuse the preform in the thickness direction. However, if one has an embedded impermeable insert in the thickness direction, it will obstruct the flow in the region below the embedded object. Several case studies are conducted to understand the effect of the geometry and placement of the embedded insert and the distribution media lay out and properties on the impregnation of the resin into the fiber preform. Finally, an approach is outlined to modify the layout of the distribution media in order to ensure a complete saturation of the preform under all but the most extreme conditions. The approach is validated with experiments. POLYM. COMPOS., 28:442,450, 2007. © 2007 Society of Plastics Engineers [source] Recovery of Growth of Hyphochytrium catenoides after Exposure to Environmental StressTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 4 2008FRANK H. GLEASON ABSTRACT. The survival of an isolate of Hyphochytrium catenoides collected from soil in the Blue Mountains in eastern New South Wales, Australia, was tested under extreme conditions in the laboratory. This isolate recovered growth after being subjected to drying on filter paper, to heat while desiccated, to hypersalinity, to strict anaerobic conditions, to freezing temperatures, and to a short period in solutions at pH 2.8,11.2. The capacity to survive under these conditions in the laboratory suggests adaptation to fluctuating conditions in the soil. The partial DNA sequence of the 28S ribosomal RNA gene in the isolate from New South Wales was 98% similar to that in an isolate from Arizona with a similar morphology. [source] Physiological responses of lupin genotypes to terminal drought in a Mediterranean-type environmentANNALS OF APPLIED BIOLOGY, Issue 3 2007J.A. Palta Abstract Field experiments concerning lupin grown in a low-rainfall environment of the Mediterranean climatic region of Western Australia were conducted over three seasons to identify and evaluate the characteristics that maximise yield per unit of rainfall. The characteristics of early flowering and podding, high pod retention, fast rates of seed filling, osmotic adjustment and the degree of dry matter transfer from stem to the seed were studied in 12 lupin genotypes differing in seed yield under conditions of terminal drought. To allow recently released cultivars and advanced breeding lines to be evaluated, five to six genotypes were included in the first and the third year and nine in the second year. The genotypes were grown rainfed until pod set and then under a rainout shelter. Flowering and podding dates, pod retention, seed growth rate and osmotic adjustment were measured in detail, together with leaf water potential, seed yield and its components. The timing and intensity of development of the terminal drought varied from average in 1998 and 1999 to extreme in 2000. In each year, the seed yield under terminal drought showed genotypic differences, which appeared consistent with the timing and intensity of the development of terminal drought. Early flowering and podding were significantly correlated with seed yield. Fast rates of seed growth were highly and significantly correlated with high yields regardless of the intensity of development of terminal drought. Pod retention was highly correlated with yield in seasons in which the intensity of the development of terminal drought was average but not under extreme conditions of terminal drought. This was because the seed number per pod was markedly reduced to compensate for the high number of pods retained. Osmotic adjustment did not occur during the development of terminal drought in any of the genotypes. Dry matter transfer from stems to seeds was insignificant and not related to seed yield, suggesting that it is not a useful characteristic in screening for high yield under terminal drought. [source] "Enzyme Test Bench," a high-throughput enzyme characterization technique including the long-term stabilityBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2009Kirill Rachinskiy Abstract A new high throughput technique for enzyme characterization with specific attention to the long term stability, called "Enzyme Test Bench," is presented. The concept of the Enzyme Test Bench consists of short term enzyme tests in 96-well microtiter plates under partly extreme conditions to predict the enzyme long term stability under moderate conditions. The technique is based on the mathematical modeling of temperature dependent enzyme activation and deactivation. Adapting the temperature profiles in sequential experiments by optimal non-linear experimental design, the long term deactivation effects can be purposefully accelerated and detected within hours. During the experiment the enzyme activity is measured online to estimate the model parameters from the obtained data. Thus, the enzyme activity and long term stability can be calculated as a function of temperature. The engineered instrumentation provides for simultaneous automated assaying by fluorescent measurements, mixing and homogenous temperature control in the range of 10,85,±,0.5°C. A universal fluorescent assay for online acquisition of ester hydrolysis reactions by pH-shift is developed and established. The developed instrumentation and assay are applied to characterize two esterases. The results of the characterization, carried out in microtiter plates applying short term experiments of hours, are in good agreement with the results of long term experiments at different temperatures in 1 L stirred tank reactors of a week. Thus, the new technique allows for both: the enzyme screening with regard to the long term stability and the choice of the optimal process temperature regarding such process parameters as turn over number, space time yield or optimal process duration. The comparison of the temperature dependent behavior of both characterized enzymes clearly demonstrates that the frequently applied estimation of long term stability at moderate temperatures by simple activity measurements after exposing the enzymes to elevated temperatures may lead to suboptimal enzyme selection. Thus, temperature dependent enzyme characterization is essential in primary screening to predict its long term behavior. Biotechnol. Bioeng. 2009;103: 305,322. © 2008 Wiley Periodicals, Inc. [source] | ||||||||||||||||||||||