Formation of a submicrocrystalline structure in metastable austenitic steels during severe plastic deformation and subsequent heating

The structure and the mechanical properties of metastable austenitic steels after severe plastic deformation by four or six passes of equal-channel angular pressing (ECAP) at a temperature of 400°C are studied. It is shown that ECAP results in strain hardening mainly due to the formation of a submicrocrystalline structure, which is retained after subsequent heating to 500°C.     

Identification and quantification of arsenolipids using reversed-phase HPLC coupled simultaneously to high-resolution ICPMS and high-resolution electrospray MS without species-specific standards

Although it has been known for decades that arsenic forms fat-soluble arsenic compounds, only recent attempts to identify the compounds have been successful by using a combination of fractionation and elemental and molecular mass spectrometry. Here we show that arsenolipids can directly be identified and quantified in biological extracts using reversed-phase high-performance liquid chromatography (RP-HPLC) simultaneously online-coupled to high-resolution inductively coupled plasma mass spectrometry (ICPMS) and high-resolution electrospray mass spectrometry (ES-MS) without having a lipophilic arsenic standard available. Using a methanol gradient for the separation made it necessary to use a gradient-dependent arsenic response factor for the quantification of the fat-soluble arsenic species in the extract. The response factor was obtained by using the ICPMS signal of known concentration of arsenic. The arsenic response was used to determine species-specific response factors for the different arsenic species. The retention time for the arsenic species was utilized to mine the ES-MS data for accurate mass and their tandem mass spectrometry (MS/MS) fragmentation pattern to give information of molecular formula and structure information. The majority of arsenolipids, found in the hexane phase of fish meal from capelin ( Mallotus villosus ) was in the form of three dimethylarsinoyl hydrocarbons (C(23)H(38)AsO, C(17)H(38)AsO, C(19)H(42)AsO) with minor amounts of dimethylarsinoyl fatty acids (C(17)H(36)AsO(3), C(23)H(38)AsO(3), C(24)H(38)AsO(3)). One of the dimethylarsinoyl fatty acids (C(24)H(38)AsO(3)), with an even number of carbon in the fatty acid chain, was identified for the first time in this work. This molecular formula is unusual and in contrast to all previously identified arsenic-containing fatty acids with odd numbers of carbon.     

Formation and transformation of hierarchical structure of β-nucleated polypropylene characterized by X-ray diffraction, differential scanning calorimetry and scanning electron microscopy

Commercial grade isotactic polypropylene has been modified with a specific β-nucleant (N,N′-dicyclohexylnaphthalene-2,6-dicarboxamide) in two concentrations (0.03 and 0.10 wt%). Specimens for structural characterization have been prepared by injection moulding, subsequent melting and re-crystallization or solid-state drawing at 100 °C. Individual levels of hierarchical structure, including molecular orientation, have been characterized by a combination of wide angle X-ray scattering (WAXS), differential scanning calorimetry and scanning electron microscopy. Based on the analysis of the azimuthal reflections (110) and (300), the Hermans orientation functions have been calculated separately for the crystalline phases α and β. Besides the longitudinal orientation along the injection-moulding direction, β-crystallites tilted to the injection-moulding direction have been found. Upon thermal treatment the fraction of the crystalline β-phase has decreased and molecular alignment within the crystalline regions has improved. During solid-state drawing the fraction of the crystalline β-phase was markedly decreasing with increasing draw ratio, while the overall crystallinity has not changed but slightly. The experiments have also revealed a disruption of molecular alignment at the beginning of the drawing process and subsequent distinct improvement of molecular orientation along the draw direction in crystallites α and β. The Hermans orientation functions provided by the WAXS analysis have been compared with recently published data obtained with similar specimens by polarized photoacoustic spectroscopy.     

The role of the general practitioner in the community care of people with HIV infection and AIDS: a comparative study of high- and low-prevalence areas in England

BACKGROUND: Policy for the care of people suffering from HIV and AIDS has changed over the past decade. Schemes for shared primary and secondary care have been met with varying success, and patients may be reluctant to become involved. No systematic evaluation comparing the views of primary care providers and users in areas of varying HIV prevalence has been published. AIM: To examine the role of general practice in areas of England with low and high human immunodeficiency virus (HIV) prevalence and to compare barriers to general practice care in each area. METHOD: We used focus groups, semistructured questionnaires and interviews in north London (high HIV prevalence) and Nottingham (low HIV prevalence). RESULTS: Four focus groups took place in London. A total of 411 general practitioners (GPs) in London and 405 in Nottingham replied to postal questionnaires. Overall, 121 primary care staff in 40 London practices and 26 staff in five Nottingham practices were interviewed. In all, 54 people infected with HIV were interviewed in London and 20 in Nottingham. Providers and users regarded the 24-hour availability and the familiar environment of general practice as its key assets. Lack of expertise and time were its disadvantages. Providers were concerned about inadequate communication with specialist services. Although providers were concerned about confidentiality, whether they had liberal and sympathetic attitudes was more important in deciding whether people with HIV used the service. In the low-prevalence area, general practice involvement was the result of individual initiatives, and practices were not integrated into specialist care. In the high-prevalence area, HIV care was more usual in general practice, but there was also little integration with HIV services. CONCLUSIONS: In high-prevalence districts, a strategy to make HIV care routine for all GPs may be appropriate. In low-prevalence areas, a network of selected, strategically located, relatively high-involvement practices may be more effective in meeting the primary care needs of people with HIV infection and acquired immunodeficiency syndrome (AIDS).     

In vitro selection of peptides acting at a new site of NMDA glutamate receptors

Oligomeric N-methyl D-aspartate receptor (NMDAR) in brain is a ligand-gated ion channel that becomes selectively permeable to ions upon binding to ligands. For NMDAR channel, the binding of glutamate and glycine results in opening of the calcium permeable channel. Because the calcium influx mediated by NMDAR is important for synaptic plasticity and excitotoxicity, the function of NMDA receptors has been implicated in both health and disease. Native NMDA receptors are thought to be heteromeric pentamers with a central ion conduction pathway. There are five genes (NR1, 2A, 2B, 2C, and 2D) encoding various subunits that have been cloned, and NR1 is thought to be the essential subunit since it forms a functional channel by itself. To study NMDAR structure and function, we have searched for peptide modulators of NR1 using random peptide bacteriophage libraries. The peptides were identified based on their specific association with a purified receptor fusion protein that contains the putative ligand binding domain. We report the identification of one group of cyclic peptides (Mag-1) with a consensus sequence of CDGLRHMWFC. Using biochemical binding analysis and patch clamp electrophysiological recording, we show that the synthetic Mag-1 peptides cause noncompetitive inhibition of the receptor channel activity.     

Interlayer bonding of binder,base and subbase layers of asphalt pavements: Long-term performance

With bond testing of asphalt layers becoming a more important topic as well as in research as in every day pavement construction, the question of long term behaviour of bonding properties has come up. In recent research it has been shown that the bonding properties between surface and binder courses seem to improve with time considering that the surface course does not show distress phenomena and that the traffic volume does not exceed the traffic considered for pavement design. That bond failure is not only a question of the top layers is a well known fact; therefore the long term properties of the lower layers are also of interest. The paper focuses on the effect of long term behaviour of bonding properties of the lower pavement layers (binder or base and subbase courses) presenting the results of an extensive Swiss study. The study compares the bonding properties determined with the layer parallel shear test (LPDS) according to Leutner of high volume roads after a 9–13 years period. It was found that for rehabilitations or old constructions an improvement cannot be expected and especially in case of old constructions seems to depend on their service life. For the bond between lower layers decreases of shear force values down to 50% are possible.     

Thermal design and analysis of a multi-stage 30 K radiative cooling system for EPIC

The Experimental Probe of Inflationary Cosmology (EPIC) is an implementation of the NASA Einstein Inflation Probe mission, to answer questions about the physics of Inflation in the early Universe by measuring the polarization of the Cosmic Microwave Background (CMB). The mission relies on a passive cooling system to cool the enclosure of a telescope to 30 K; a cryocooler then cools this enclosure to 18 K and the telescope to 4 K. Subsequently, an Adiabatic Demagnetization Refrigerator further cools a large Focal Plane to ∼100 mK. For this mission, the telescope has an aperture of 1.4 m, and the spacecraft’s symmetry axis is oriented ∼45° relative to the direction of the sun. The spacecraft will be spun at ∼0.5 rpm around this axis, which then precesses on the sky at 1 rph. The passive system must both supply the necessary cooling power for the cryocooler and meet demanding temperature stability requirements. We describe the thermal design of a passive cooling system consisting of four V-groove radiators for shielding of solar radiation and cooling the telescope to 30 K. The design realizes loads of 20 and 68 mW at the 4 K and 18 K stages on the cooler, respectively. A lower cost option for reaching 40 K with three V-groove radiators is also described. The analysis includes radiation coupling between stages of the radiators and sunshields, and parasitic conduction in the bipod support, harnesses, and ADR leads. Dynamic effects are also estimated, including the very small variations in temperature due to the scan motion of the spacecraft.     

Reconstructive surgery for ischemic-type lesions at the bile duct bifurcation after liver transplantation

Cholestatic liver injury appears to result from the induction of hepatocyte apoptosis by toxic bile salts such as glycochenodeoxycholate (GCDC). Previous studies from this laboratory indicate that cathepsin B is a downstream effector protease during the hepatocyte apoptotic process. Because caspases can initiate apoptosis, the present studies were undertaken to determine the role of caspases in cathepsin B activation. Immunoblotting of GCDC-treated McNtcp.24 hepatoma cells demonstrated cleavage of poly(ADP-ribose) polymerase and lamin B1 to fragments that indicate activation of effector caspases. Transfection with CrmA, an inhibitor of caspase 8, prevented GCDC-induced cathepsin B activation and apoptosis. Consistent with these results, an increase in caspase 8-like activity was observed in GCDC-treated cells. Examination of the mechanism of GCDC-induced caspase 8 activation revealed that dominant-negative FADD inhibited apoptosis and that hepatocytes isolated from Fas-deficient lymphoproliferative mice were resistant to GCDC-induced apoptosis. After GCDC treatment, immunoprecipitation experiments demonstrated Fas oligomerization, and confocal microscopy demonstrated DeltaFADD-GFP (Fas-associated death domain-green fluorescent protein, aggregation in the absence of detectable Fas ligand mRNA. Collectively, these data suggest that GCDC-induced hepatocyte apoptosis involves ligand-independent oligomerization of Fas, recruitment of FADD, activation of caspase 8, and subsequent activation of effector proteases, including downstream caspases and cathepsin B.