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We combine liquid chromatography coupled with ion mobility spectrometry–mass spectrometry to elucidate how short exposure to corticosterone (Cort) alters the output of mouse pancreatic islet hormones. The workflow enables the robust separation of mouse insulin 1 (Ins1) and insulin 2 (Ins2) and the detection of major islet hormones in a homogenate equivalent to 100–150 islet cells. We show that Ins2 has a unique structure and is degraded much faster than Ins1. Further investigation indicates that Ins2 may populate both T and R states, whereas Ins1 may not. The assemblies of Ins1’s B-chain also introduce more structural heterogeneity than Ins2. Collectively, these features account for their unique degradation profiles, the diabetes risk associated with Ins1, and the protective effect of Ins2. In the same experiments, we observe that the ratio of amylin to Ins1 increased significantly in Cort-treated mice (15:1) compared to the control mice (42:1), correlating well with β-cell proliferation observed in immunoassays on the same animal model. We observe no increase in intact full-length insulin levels but more of the truncated forms, indicating that enzymatic activity is accelerated. Our data provide a molecular basis for reduced insulin action induced by Cort and connections between insulin turnover and insulin resistance.

Despite considerable efforts over the past decade, only 34 fast radio bursts—intense bursts of radio emission from beyond our Galaxy—have been reported1,2. Attempts to understand the population as a whole have been hindered by the highly heterogeneous nature of the searches, which have been conducted with telescopes of different sensitivities, at a range of radio frequencies, and in environments corrupted by different levels of radio-frequency interference from human activity. Searches have been further complicated by uncertain burst positions and brightnesses—a consequence of the transient nature of the sources and the poor angular resolution of the detecting instruments. The discovery of repeating bursts from one source3, and its subsequent localization4to a dwarf galaxy at a distance of 3.7 billion light years, confirmed that the population of fast radio bursts is located at cosmological distances. However, the nature of the emission remains elusive. Here we report a well controlled, wide-field radio survey for these bursts. We found 20, none of which repeated during follow-up observations between 185–1,097 hours after the initial detections. The sample includes both the nearest and the most energetic bursts detected so far. The survey demonstrates that there is a relationship between burst dispersion and brightness and that the high-fluence bursts are the nearby analogues of the more distant events found in higher-sensitivity, narrower-field surveys5.

Steroid-induced diabetes is the most common form of drug-induced hyperglycemia. Therefore, metabolic and immunological alterations associated with chronic oral corticosterone were investigated using male nonobese diabetic mice. Three weeks after corticosterone delivery, there was reduced sensitivity to insulin action measured by insulin tolerance test. Body composition measurements revealed increased fat mass and decreased lean mass. Overt hyperglycemia (>250 mg/dL) manifested 6 weeks after the start of glucocorticoid administration, whereas 100% of the mice receiving the vehicle control remained normoglycemic. This phenotype was fully reversed during the washout phase and readily reproducible across institutions. Relative to the vehicle control group, mice receiving corticosterone had a significant enhancement in pancreatic insulin-positive area, but a marked decrease in CD3+cell infiltration. In addition, there were striking increases in both citrate synthase gene expression and enzymatic activity in skeletal muscle of mice in the corticosterone group relative to vehicle control. Moreover, glycogen synthase expression was greatly enhanced, consistent with elevations in muscle glycogen storage in mice receiving corticosterone. Corticosterone-induced hyperglycemia, insulin resistance, and changes in muscle gene expression were all reversed by the end of the washout phase, indicating that the metabolic alterations were not permanent. Thus, male nonobese diabetic mice allow for translational studies on the metabolic and immunological consequences of glucocorticoid-associated interventions in a mouse model with genetic susceptibility to autoimmune disease.

The current Astra laser facility is capable of Terawatt operation at 10 Hz into one experimental area, and simultaneous 12 TW operation at 1 Hz into a second area. Both of these operational modes deliver a single beam with a pulse duration of 40 fs and a few times diffraction-limited quality. The Astra Gemini project will extend the capabilities of Astra to Petawatt level by providing two 0.5 PW beams in a completely new radiation-shielded interaction area. The new facility will be able to deliver two beams of 15 J in 30 fs at a rate of one shot per minute, and will support a wide range of experimental configurations, opening up many new possibilities for high-intensity laser-matter interaction studies.

Petawatt capability on the Vulcan laser facility has been available to the international plasma physics community for over two years. This has enabled novel experiments to be carried out and new regimes of physics to be explored. During that time, there have been 10 successful user experiments with 89% of shots delivered within the requested energy limits. In the autumn of 2004, pulses with powers of more than a petawatt (1015 Watts) were delivered to target with energies greater than 400 J and pulse widths shorter than 500 femtoseconds (10$^{ - 15})$on target. In parallel to the development of ultra-high intensity pulses is a programme to enhance Vulcan's long pulse capabilities. This paper will present an overview of the current capabilities of the Vulcan Petawatt facility and discuss some of the recent technological advances that have enabled the generation of Petawatt pulses.

FGF21 contributes to the metabolic response to dietary protein restriction, and prior data implicate GCN2 as the amino acid sensor linking protein restriction to FGF21 induction. Here, we demonstrate the persistent and essential role of FGF21 in the metabolic response to protein restriction. We show that Fgf21KO mice are fully resistant to low protein (LP)-induced changes in food intake, energy expenditure (EE), body weight gain, and metabolic gene expression for 6 months. Gcn2KO mice recapitulate this phenotype, but LP-induced effects on food intake, EE, and body weight subsequently begin to appear after 14 days on diet. We show that this delayed emergence of LP-induced metabolic effects in Gcn2KO mice coincides with a delayed but progressive increase of hepatic Fgf21expression and blood FGF21 concentrations over time. These data indicate that FGF21 is essential for the metabolic response to protein restriction but that GCN2 is only transiently required for LP-induced FGF21.

This paper summarises the main results obtained during the two experimental campaigns on TCE X-ray lasers that we have carried out since the last Kyoto X-ray laser Conference in 1998. A two-color ([MATH]) pumping configuration was tested and led to the observation of a strong lasing line at 16 nm, identified to a 4f-4d transition in Ni-like Ag. A strong x 300-400 enhancement of the 13.9 nm Ni-like 4d-4p lasing emission was obtained when a traveling wave short pulse pumping was applied. Finally the temporal history of the 13.9 nm laser pulse was measured with a high-resolution Streak camera. A very short, 2 ps X-ray laser pulse was directly demonstrated for the first time.

We report on a time-resolved study of a Ni-like transient collisionnal X-ray laser with a resolution as high as 1.9 ps. The FWHM duration of the Ni-like x-ray laser pulse at 13.99 nm [MATH] line is measured to be as short as [MATH] at optimum conditions of pump laser irradiation. This is about four times shorter than was estimated in previous experiments. The x-ray laser signal appears in the rising edge of the continuum emission. The x-ray laser duration rises significantly when the short (heating) pulse duration is increased and when doubling the peak-to-peak delay of the two irradiation pulses. It does not change when the short pulse energy is increased. The results presented are the first direct measurements of the temporal profile of the x-ray laser output at a high resolution.

In this paper we present details of a scalable design for a cryogenic helium gas cooled DPSSL amplifier based on a multislab Yb:YAG geometry. A prototype amplifier design capable of efficient amplification of 10 ns pulses to 10 J at 10 Hz is presented, which has been derived from computational fluid dynamic calculations and thermal modeling. Model predictions have also been used to design a suitable cryogenic gas cooling system, details of which are also presented. Experimental testing has confirmed stable amplifier temperatures are achievable from room temperature down to 88 K, with a gas coolant temperature stability of ±0.2  K. Single-pass transmission wave front measurements are in reasonable agreement with model predictions derived from thermal maps for two different YAG slab geometries. Slabs with a narrower width Cr-doped YAG absorptive cladding, added to suppress ASE, demonstrated a wave front error of ∼0.2 waves at 1030 nm (peak-to-valley) over the 20  mm×20  mm pumped region within the amplifier. The low level of optical distortion confirms that the amplifier design provides an acceptable level of temperature and flow uniformity and demonstrates the merit of a multislab geometry.

Deux alliages à mémoire de forme, NiTi et Ni47Ti50Co3ont fait l'objet d'une étude comparative vis à vis des transformations structurales intervenant sous l'effet de la température. Les résultats obtenus par calorimétrie différentielle à balayage (DSC) et par mesures de frottement intérieur (FI) permettent de définir de façon certaine la chronologie des transformations : "austénite"→phase-R→"martensite" au refroidissement et martensite→phase-R→austénite au chauffage, lorsque les hystérésis des transformations le permettent. Des expériences de cyclages thermiques montrent qu'il peut y avoir une inversion apparente dans le séquence des transformations au chauffage mais cela résulte d'une transformation martensitique directe partielle. La différence majeure entre ces deux alliages est le décalage en température, des hystérésis et donc des transformations M ↔ R et R ↔ A.

We present a 2D P‐wave velocity model from the outer rise region of the Lesser Antilles island arc, the first wide‐angle seismic study of outer rise processes at an Atlantic subduction zone. The survey consists of 46 OBS receivers over a 174 km profile with velocities resolved to 15 km below top basement. The final velocity model, produced through tomographic inversion, shows a clear decrease in the velocity of the lower crust and upper mantle of the incoming plate as it approaches the trench. We attribute this drop to outer rise bend‐related hydration, similar to Pacific cases, but superimposed on spatial variations in hydration generated at the slow‐spreading ridge axis. In thin, tectonically controlled crust formed under magma‐poor spreading conditions the superposition of these sources of hydration results in compressional velocities as low as 6.5 km s−1beneath the PmP reflector. In contrast, segments of crust interpreted as having formed under magma‐rich conditions show velocity reductions and inferred hydrous alteration more like that observed in the Pacific. Hence, variations in the style of crustal accretion, which is observed on 50–100 km length scales both along and across isochrons, is a primary control over the distribution of water within the slab at Atlantic subduction systems. This heterogeneous pattern of water storage within the slab is likely further complicated by along strike variations in outer rise bending, subducting fracture zones and deformation at segment ends and may have important implications for our understanding of long‐term patterns of hazard at Atlantic subduction systems. Subduction zones are locations where one of the Earth's tectonic plates is dragged below the other into the mantle. These are locations of significant seismic and volcanic hazard. Water present in the down‐going plate plays an important role in determining the distribution of these hazards. In well‐studied Pacific subduction zones much of this water enters the down‐going plate as it is deformed just prior to subduction in a region known as the outer rise. This hydration can be estimated using seismic techniques which measure the time energy takes to travel through the plate, with altered “wet” rocks shown to be anonymously slow. As the structure of the crust in the Pacific is relatively uniform this hydration is evenly distributed. At Atlantic subduction zones such as the Lesser Antilles the structure of the subducting plate is more variable due to a poor magma supply at the ridge where it forms, leading to highly deformed and thinner crust. Our seismic experiment shows the subducting plate is extremely wet, having been exposed to two distinct phases of hydration, one during its formation and another across the outer rise. This may be the root‐cause for many of the unusual characteristics of this subduction system. We identify very low mantle P‐wave velocities on the order of 6.5 km s−1in the outer rise region of the Lesser Antilles subduction zoneVelocities are the result of two phases of hydrous alteration during accretion at the Mid‐Atlantic Ridge and bending at the outer riseOur results imply that water distribution within the slab is heterogeneous on 50–100 km length scales We identify very low mantle P‐wave velocities on the order of 6.5 km s−1in the outer rise region of the Lesser Antilles subduction zone Velocities are the result of two phases of hydrous alteration during accretion at the Mid‐Atlantic Ridge and bending at the outer rise Our results imply that water distribution within the slab is heterogeneous on 50–100 km length scales

HiPER is the European Project for Laser Fusion that has been able to join 26 institutions and signed under formal government agreement by 6 countries inside the ESFRI Program of the European Union (EU). The project is already extended by EU for two years more (until 2013) after its first preparatory phase from 2008. A large work has been developed in different areas to arrive to a design of repetitive operation of Laser Fusion Reactor, and decisions are envisioned in the next phase of Technology Development or Risk Reduction for Engineering or Power Plant facilities (or both). Chamber design has been very much completed for Engineering phase and starting of preliminary options for Reactor Power Plant have been established and review here.

HiPER (High Power laser Energy Research) is the first European plan for international cooperation in developing inertial fusion energy. ICF activities are ongoing in a number of nations and the first ignition experiments are underway at the National Ignition Facility (NIF) in the USA. Although HiPER is still in the preparatory phase, it is appropriate for Europe to commence planning for future inertial fusion activities that leverage the demonstration of ignition. In this paper we shall detail some of the key points of the laser design. Some of the main topics of the laser architecture are presented and discussed.

HiPER (High Power laser Energy Research) is the first European plan for international cooperation in developing inertial fusion energy. ICF activities are ongoing in a number of nations and the first ignition experiments are underway at the National Ignition Facility (NIF) in the USA. Although HiPER is still in the preparatory phase, it is appropriate for Europe to commence planning for future inertial fusion activities that leverage the demonstration of ignition. In this paper we shall detail some of the key points of the laser design and the way this design is connected to the capsule requirements.

To generate petawatt pulses using the Vulcan Nd:glass laser requires a broad bandwidth high-gain preamplifier. The preamplifier used is an optical parametric amplifier that provides a total gain of 10^8 in three amplification stages. We report on a detailed investigation of the effect of the Vulcan optical parametric chirped pulse amplification (OPCPA) preamplifier on contrast caused by the amplified spontaneous emission (ASE) pedestal that extends up to 2 ns before the arrival of the main pulse. The contrast after compression is improved to 4×10^8 of the intensity of the main pulse using near-field apertures between the stages of the OPCPA preamplifier. Further reduction of the level of the ASE pedestal can be achieved at the cost of a reduction in amplified bandwidth by solely phosphate glass amplification after initial preamplification rather than a mixed glass amplification scheme.

With the increasing number of multi-terawatt (1012W) and petawatt (1015W) laser interaction facilities being built, the need for a detailed understanding of the potential radiological hazards is required and their impact on personnel is of major concern. Experiments at a number of facilities are being undertaken to achieve this aim. This paper describes the recent work completed on the Vulcan petawatt laser system at the CCLRC Rutherford Appleton Laboratory, where photon doses of up to 43 mSv at 1 m per shot have been measured during commissioning studies. It also overviews the shielding in place on the facility in order to comply with the Ionising Radiation Regulations 1999 (IRR99), maintaining a dose to personnel of less than 1 mSv yr?1and as low as reasonably practicable (ALARP).

The current Astra laser facility is capable of Terawatt operation at 10?Hz into one experimental area, and simultaneous 12 TW operation at 1?Hz into a second area. Both of these operational modes deliver a single beam with a pulse duration of 40 fs and a few times diffraction-limited quality. The Astra Gemini project will extend the capabilities of Astra to Petawatt level by providing two 0.5 PW beams in a completely new radiation-shielded interaction area. The new facility will be able to deliver two beams of 15 J in 30 fs at a rate of one shot per minute, and will support a wide range of experimental configurations, opening up many new possibilities for high-intensity laser-matter interaction studies.

Petawatt capability on the Vulcan laser facility has been available to the international plasma physics community for over two years. This has enabled novel experiments to be carried out and new regimes of physics to be explored. During that time, there have been 10 successful user experiments with 89% of shots delivered within the requested energy limits. In the autumn of 2004, pulses with powers of more than a petawatt (1015 Watts) were delivered to target with energies greater than 400?J and pulse widths shorter than 500 femtoseconds (10 - 15) on target. In parallel to the development of ultra-high intensity pulses is a programme to enhance Vulcan's long pulse capabilities. This paper will present an overview of the current capabilities of the Vulcan Petawatt facility and discuss some of the recent technological advances that have enabled the generation of Petawatt pulses.

Health risks associated with the inhalation of potentially toxic materials have been a topic of great public concern. In vitrocellular analyses can provide mechanistic information on the molecular-level responses of lung-derived cell lines to a variety of these hazards. This understanding may be used to develop methods to reduce the damage from such toxins or to detect early stages of their effects. Here we describe an evaluation of the alterations in gene expression of an immortalized lung cell line (A549, human type II epithelia) to a variety of inhalation health hazards including etoposide, gliotoxin, streptolysin O, methyl methansesulfonate (MMS), and Triton X-100. The A549 cells display a dose–response relationship to each toxin with initial responses including alterations in metabolic activity, increases in membrane permeability, and initiation of response genes. In general, membrane-damaging agents (streptolysin O and Triton X-100) induce production of new ion channel proteins, structural proteins, and metabolic enzymes. Gliotoxin impacted the metabolic machinery, but also altered ion channels. Etoposide and MMS caused alterations in the cell cycle, induced DNA repair enzymes, and initiated apoptotic pathways, but MMS also induced immune response cascades. The mechanism of cell response to each toxin is supported by physiological analyses that indicated a fairly slow initiation of cell response to all compounds tested, except for Triton, which caused rapid decline in cell function due to solubilization of the cell membrane. However, Triton does induce production of a number of cell membrane-associated proteins and so its effects at low concentrations are likely translated throughout the cell. Together these results indicate a broader array of cellular responses to each of the test toxins than have previously been reported.Health risks associated with the inhalation of potentially toxic materials have been a topic of great public concern. In vitrocellular analyses can provide mechanistic information on the molecular-level responses of lung-derived cell lines to a variety of these hazards. This understanding may be used to develop methods to reduce the damage from such toxins or to detect early stages of their effects. Here we describe an evaluation of the alterations in gene expression of an immortalized lung cell line (A549, human type II epithelia) to a variety of inhalation health hazards including etoposide, gliotoxin, streptolysin O, methyl methansesulfonate (MMS), and Triton X-100. The A549 cells display a dose–response relationship to each toxin with initial responses including alterations in metabolic activity, increases in membrane permeability, and initiation of response genes. In general, membrane-damaging agents (streptolysin O and Triton X-100) induce production of new ion channel proteins, structural proteins, and metabolic enzymes. Gliotoxin impacted the metabolic machinery, but also altered ion channels. Etoposide and MMS caused alterations in the cell cycle, induced DNA repair enzymes, and initiated apoptotic pathways, but MMS also induced immune response cascades. The mechanism of cell response to each toxin is supported by physiological analyses that indicated a fairly slow initiation of cell response to all compounds tested, except for Triton, which caused rapid decline in cell function due to solubilization of the cell membrane. However, Triton does induce production of a number of cell membrane-associated proteins and so its effects at low concentrations are likely translated throughout the cell. Together these results indicate a broader array of cellular responses to each of the test toxins than have previously been reported.

A de novo peptide that self-assembles into fibrillar structures and serves as a substrate for the cross-linking enzyme tissue transglutaminase was developed (Ac-QQKFQFQFEQQ-Am). Congo red staining, circular dichroism, and FTIR spectroscopy showed that this 11-amino acid peptide produced predominantly β-sheet structures. TEM with negative staining and quick-freeze deep etch (QFDE) TEM showed that the peptide structures were composed of a highly entangled fibrillar network. These β-sheet fibrillar nanostructures were then covalently coupled to pendant amine-containing biomolecules via tissue transglutaminase. MALDI-TOF mass spectrometry and HPLC were utilized to monitor the extent of the transglutaminase modification of the peptide, showing that as many as five glutamines in the peptide were reactive via transglutaminase for covalent conjugation. This strategy, based on the post-assembly modification of a self-assembling peptide, has potential applications for tailoring supramolecular structures for drug delivery, tissue engineering, or other biomedical applications.

Halogenated hydrocarbon exposure is associated with changes in gene expression in adult and embryonic tissue. Our study was undertaken to identify differentially expressed mRNA transcripts in embryonic hearts from Sprague‐Dawley rats exposed to trichloroethylene (TCE) or potential bio‐transformation products dichloroethylene (DCE) and trichloroacetic acid (TCAA).cDNA subtractive hybridization was used to selectively amplify expressed mRNA obtained from control or halogenated hydrocarbon exposed rat embryos. The doses used were 1100 and 110 ppm (8300 and 830 μM) TCE, 110 and 11 ppm (1100 and 110 μM) DCE, and 27.3 and 2.75 mg/ml (100 and 10 mM) TCAA. Control animals were given distilled drinking water throughout the period of experiments.Sequencing of over 100 clones derived from halogenated hydrocarbon exposed groups resulted in identification of numerous differentially regulated gene sequences. Up‐regulated transcripts identified include genes associated with stress response (Hsp 70) and homeostasis (several ribosomal proteins). Down‐regulated transcripts include extracellular matrix components (GPI‐p137 and vimentin) and Ca2+ responsive proteins (Serca‐2 Ca2+‐ATPase and β‐catenin). Two possible markers for fetal TCE exposure were identified: Serca‐2 Ca2+‐ATPase and GPI‐p137, a GPI‐linked protein of unknown function. Differential regulation of expression of both markers by TCE was confirmed by dot blot analysis and semi‐quantitative RT‐PCR with levels of TCE exposure between 100 and 250 ppb (0.76 and 1.9 μM) sufficient to decrease expression.Sequences down‐regulated with TCE exposure appear to be those associated with cellular housekeeping, cell adhesion, and developmental processes, while TCE exposure up‐regulates expression of numerous stress response and homeostatic genes. Birth Defects Research (Part A) 67488–495, 2003. © 2003 Wiley‐Liss, Inc.

Tibial hearings of total knee replacements are generally made from ultra-high molecular weight polyethylene (UHMWPE). Failure of those hearings has been found to result in many cases from subsurface crack initiation and propagation. Two types of subsurface-originated failure modes are investigated in this study: macroscopic contact fatigue and microscopic pitting. The cracks responsible for both modes of failure initiate in polyethylene material that has been embrittled by oxidation; this oxidation is an undesirable outcome of the gamma irradiation (in air) used to sterilize the tibial bearings. Accelerated aging was used in this work to achieve oxidation levels similar to those found in retrieved bearings. Tribotesting of the aged bearing materials was carried out under simulated service conditions using a rolling/sliding tester. Macroscopic fatigue cracks and microscopic surface pitting developed in UHMWPE specimens tested on the rolling/sliding tester, and the damage was similar to that found in retrieved tibial bearings. The fatigue cracks invariably initiated in the embrittled oxidized layer, and the number of cycles before initiation of the fatigue cracks was dependent on the oxidation level and on the contact stress.

Skeletal and cardiac myocytes cease division within weeks of birth. Although skeletal muscle retains limited capacity for regeneration through recruitment of satellite cells, resident populations of adult myocardial stem cells have not been identified. Because cell cycle withdrawal accompanies myocyte differentiation, we hypothesized that C2C12 cells, a mouse myoblast cell line previously used to characterize myocyte differentiation, also would provide a model for studying cell cycle withdrawal during differentiation. C2C12 cells were differentiated in culture medium containing horse serum and harvested at various time points to characterize the expression profiles of known cell cycle and myogenic regulatory factors by immunoblot analysis. BrdU incorporation decreased dramatically in confluent cultures 48 hr after addition of horse serum, as cells started to form myotubes. This finding was preceded by up-regulation of MyoD, followed by myogenin, and activation of Bcl-2. Cyclin D1 was expressed in proliferating cultures and became undetectable in cultures containing 40% fused myotubes, as levels of p21^WAF1/Cip1 increased and α-actin became detectable. Because C2C12 myoblasts withdraw from the cell cycle during myocyte differentiation following a course that recapitulates this process in vivo, we performed a genome-wide screen to identify other gene products involved in this process. Using microarrays containing ~10,000 minimally redundant mouse sequences that map to the UniGene database of the National Center for Biotechnology Information, we compared gene expression profiles between proliferating, differentiating, and differentiated C2C12 cells and verified candidate genes demonstrating differential expression by RT-PCR. Cluster analysis of differentially expressed genes revealed groups of gene products involved in cell cycle withdrawal, muscle differentiation, and apoptosis. In addition, we identified several genes, including DDAH2 and Ly-6A, whose expression specifically was up-regulated during cell cycle withdrawal coincident with early myoblast differentiation. 2002 Wiley-Liss, Inc.

Two series of broiler chicken feeding experiments quantified the differences in growth performance of broiler chickens fed either six different U.K. wheat cultivars from one harvest year or six wheat samples that comprised two cultivars (Dean and Beaver) each grown in three harvest years. Differences in broiler growth performance were compared to four rapid tests of wheat quality (specific weight, Hagberg falling number, water-extract viscosity and endosperm hardness) and the determined true metabolisable energy. Broilers fed the cultivar Dean had higher (P<0·001) weight gains and lower (P<0·05) feed conversion ratios compared to those fed Beaver. Samples from a harvest year (1992) in which there was high rainfall in the month during which harvest occurred resulted in lower (P<0·05) broiler feed conversion ratios. Endosperm hardness and water-extract viscosity were both linearly related (P<0·05) to differences in broiler feed conversion ratios but there was no (P>0·05) reduction in unaccountable variation from including both variables in a multiple regression analysis. The measurement of endosperm hardness by near infra-red spectroscopy is rapid and has the potential to be used to discriminate nutritive value between wheat samples on their arrival at poultry feed mills.

We present the design of a single-shot third-order autocorrelator that can be used to measure optical pulse lengths of ultrashort pulses within a fixed time window on a single-shot basis. It has a number of advantages over traditional second-order autocorrelation devices, namely a more direct and accurate measurement of pulse shape, the ability to differentiate temporal activity ahead and behind the pulse, and an increased dynamic range. The design is linear and is, in principle, no more difficult to construct and operate than a second-order autocorrelator.

Effective elongational viscosities were measured for high- and low-density polyethylene samples using a capillary rheometer fitted with semihyperbolic dies. These dies establish a purely elongational flow field at constant elongational strain rate. The effective elongational viscosities were evaluated under the influence of the process strain rate, Hencky strain, and temperature. Enthalpy and entropy changes associated with the orientation development of semihyperbolic-processed melts were also estimated. The results showed that elongational viscosities were primarily affected by differences in the weight-average molecular weight rather than in the degree of branching. This effect was process-strain-rate- as well as temperature-dependent. An investigation of the melt-pressure relaxation and the associated first decay time constants revealed that with increasing strain rate the molecular field of the melt asymptotically gained orientation in approaching a limit. As a result of this behavior, molecular uniqueness became much less distinct at high process strain rates, apparently yielding to orientation development and the associated restructuring of the melt's molecular morphology. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2170–2184, 2001

Preparation and shear and elongational rheology of cellulose solutions of different degrees of polymerization (DP) in N-methylmorpholine oxide monohydrate (lyocell) were investigated. The dissolution process takes place in two stages, depending on the content of low and high DP fractions from the dissolving pulp blends. The influence of the DP of cellulosic chains on elongational and shear viscosity is greater at low deformation rates. Low DP solutions behave more like viscous fluids and the increase of the chain length brings about an increase of the elastic component. Orientation induced by the convergence flow is enhanced by the higher DP cellulosic chains. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 396–405, 2001