The effects of silica fillers on the gelation and vitrification of highly filled epoxy-amine thermosets

Highly filled thermosets are used in applications such as integrated circuit (IC) packaging. However, a detailed understanding of the effects of the fillers on the macroscopic cure properties is limited by the complex cure of such systems. This work systematically quantifies the effects of filler content on the kinetics, gelation and vitrification of a model silica-filled epoxy/amine system in order to begin to understand the role of the filler in IC packaging cure. At high cure temperatures (100 degreesC and above) there appears to be no effect of fillers on cure kinetics and gelation and vitrification times. However, a decrease in the gelation and vitrification times and increase the reaction rate is seen with increasing filler content at low cure temperatures (60-90 degreesC). An explanation for these results is given in terms of catalysation of the epoxy amine reaction by hydrogen donor species present on the silica surface and interfacial effects.

Apoptotic deletion of Th cells specific for the 19-kDa carboxyl-terminal fragment of merozoite surface protein 1 during malaria infection

Immunity induced by the 19-kDa fragment of merozoite surface protein 1 is dependent on CD4(+) Th cells. However, we found that adoptively transferred CFSE-labeled Th cells specific for an epitope on Plasmodium yoelii 19-kDa fragment of merozoite surface protein 1 (peptide (p)24), but not OVA-specific T cells, were deleted as a result of P. yoelii infection. As a result of infection, spleen cells recovered from infected p24-specific T cell-transfused mice demonstrated reduced response to specific Ag. A higher percentage of CFSE-labeled p24-specific T cells stained positive with annexin and anti-active caspase-3 in infected compared with uninfected mice, suggesting that apoptosis contributed to deletion of p24-specific T cells during infection. Apoptosis correlated with increased percentages of p24-specific T cells that stained positive for Fas from infected mice, suggesting that P. yoelii-induced apoptosis is, at least in part, mediated by Fas. However, bystander cells of other specificities also showed increased Fas expression during infection, suggesting that Fas expression alone is not sufficient for apoptosis. These data have implications for the development of immunity in the face of endemic parasite exposure.

A dileucine motif targets E-cadherin to the basolateral cell surface in Madin-Darby canine kidney and LLC-PK1 epithelial cells

E-cadherin is a major adherens junction protein of epithelial cells, with a central role in cell-cell adhesion and cell polarity. Newly synthesized E-cadherin is targeted to the basolateral cell surface, We analyzed targeting information in the cytoplasmic tail of E-cadherin by utilizing chimeras of E-cadherin fused to the ectodo- main of the interleukin-2 alpha (IL-2 alpha) receptor expressed in Madin-Darby canine kidney and LLC-PK1 epithelial cells, Chimeras containing the full-length or membrane-proximal half of the E-cadherin cytoplasmic tail were correctly targeted to the basolateral domain. Sequence analysis of the membrane-proximal tail region revealed the presence of a highly conserved dileucine motif, which was analyzed as a putative targeting signal by mutagenesis. Elimination of this motif resulted in the loss of Tac/E-cadherin basolateral localization, pinpointing this dileucine signal as being both necessary and sufficient for basolateral targeting of E-cadherin, Truncation mutants unable to bind beta -catenin were correctly targeted, showing, contrary to current understanding, that beta -catenin is not required for basolateral trafficking. Our results also provide evidence that dileucine mediated targeting is maintained in UC-PK, cells despite the altered polarity of basolateral proteins with tyrosine-based signals in this cell line, These results provide the first direct insights into how E-cadherin is targeted to the basolateral membrane.

The surface accessibility of the glycine receptor M2-M3 loop is increased in the channel open state

Mutations in the extracellular M2-M3 loop of the glycine receptor (GlyR) alpha1 subunit have been shown previously to affect channel gating. In this study, the substituted cysteine accessibility method was used to investigate whether a structural rearrangement of the M2-M3 loop accompanies GlyR activation. All residues from R271C to V277C were covalently modified by both positively charged methanethiosulfonate ethyltrimethylammonium (MTSET) and negatively charged methanethiosulfonate ethylsulfonate (MTSES), implying that these residues form an irregular surface loop. The MTSET modification rate of all residues from R271C to K276C was faster in the glycine-bound state than in the unliganded state. MTSES modification of A272C, L274C, and V277C was also faster in the glycine-bound state. These results demonstrate that the surface accessibility of the M2-M3 loop is increased as the channel transitions from the closed to the open state, implying that either the loop itself or an overlying domain moves during channel activation.

Horizontal transmission of entomopathogenic fungi by the diamondback moth

The relative potential of the pathogenic fungi Beauveria bassiana and Zoophthora radicans for use as autodisseminated biological control agents of the diamondback moth (Plutella xylostella) was compared. The LC50 of B. bassiana conidia to third instar larvae was 499 conidia/mm(2) of leaf surface and individual cadavers of mycosed fourth instar larvae yielded a mean of 67.5 X 10(6) (+/- 7.5 x 10(6)) conidia. All concentrations of B. bassiana tested in inoculation chambers (0.24, 2.4, and 6.2 mug/mm(2)) induced 100% mortality in adult male moths within 7 days. The times to death and sporulation were concentration and exposure duration dependent. A standard procedure for inoculating male moths resulted in > 85% mortality from Z. radicans and > 93% mortality from B. bassiana. Pairing of inoculated males with clean moths of both sexes yielded higher rates of passive transmission of B. bassiana than Z. radicans, but there was no evidence for sexual transmission of either pathogen. Similarly, B. bassiana was more effectively transmitted from inoculated male moths to larvae foraging on whole plants. Single sporulating cadavers producing B. bassiana or Z. radicans conidia placed on plants infested with larvae resulted in a similar rate of transmission for both pathogens. However, an increase of the density of sporulating cadavers from one to three/plant increased Z. radicans transmission (greater than fourfold) but had no effect on B. bassiana transmission. Simultaneous inoculations of larvae with conidia of both fungi reduced the mortality induced by each pathogen, the reduction being most acute for B. bassiana-induced mortality. Inoculation of adults with both fungi showed that, at concentrations required for effective passive transmission to larvae, B. bassiana severely inhibited Z. radicans mycosis in adults. (C) 2001 Academic Press.

Pre- and postsynaptic actions of ATP on neurotransmission in rat submandibular ganglia

The pre- and postsynaptic actions of exogenously applied ATP were investigated in intact and dissociated parasympathetic neurotics of rat submandibular ganglia. Nerve-evoked excitatory postsynaptic potentials (EPSPs) were not inhibited by the purinergic receptor antagonists, suramin and pyridoxal-phosphate-6-azophenyl-2 ' ,4 ' -disulphonic acid (PPADS), or the desensitising agonist, alpha,beta -methylene ATP. In contrast. EPSPs were abolished by the nicotinic acetylcholine receptor antagonists, hexamethonium and mecamylamine. Focal application of ATP (100 muM) had no effect on membrane potential of the postsynaptic neurone or on the amplitude of spontaneous EPSPs. Taken together, these results suggest the absence of functional purinergic (P2) receptors on the postganglionic neurone in situ. In contrast, focally applied ATP (100 muM) reversibly inhibited nerve-evoked EPSPs. Similarly, bath application of the non-hydrolysable analogue of ATP, ATP gammaS, reversibly depressed EPSPs amplitude, The inhibitory effects of ATP and ATP gammaS on nerve-evoked transmitter release were antagonised by bath application of either PPADS or suramin, suggesting ATP activates a presynaptic P2 purinoceptor to inhibit acetylcholine release from preganglionic nerves in the submandibular ganglia. In acutely dissociated postganglionic neurotics from rat submandibular ganglia. focal application of ATP (100 LM) evoked an inward current and subsequent excitatory response and action potential firing, which was reversibly inhibited by PPADS (10 muM). The expression of P2X purinoceptors in wholemount and dissociated submandibular ganglion neurones was examined using polyclonal antibodies raised against the extracellular domain of six P2X purinoceptor subtypes (P2X(1-6)). In intact wholemount preparations, only the P2X(5) purinoceptor subtype was found to be expressed in the submandibular ganglion neurones and no P2X immunoreactivity was detected in the nerve fibres innervating the ganglion. Surprisingly, in dissociated submandibular ganglion neurones, high levels of P2X(2) and P2X(4) purinoceptors immunoreactivity were found on the cell surface. This increase in expression of P2X(2) and P2X(4) purinoceptors in dissociated submandibular neurones could explain the increased responsiveness of the neurotics to exogenous ATP. We conclude that disruption of ganglionic transmission in vivo by either nerve damage or synaptic blockade may up-regulate P2X expression or availability and alter neuronal excitability. (C) 2001 IBRO. Published by Elsevier Science Ltd. All rights reserved.

MUC13, a novel human cell surface mucin expressed by epithelial and hemopoietic cells

Transmembrane mucins are glycoproteins involved in barrier function in epithelial tissues. To identify novel transmembrane mucin genes, we performed a tblastn search of the GenBank(TM) EST data bases with a serine/ threonine-rich search string, and a rodent gene expressed in bone marrow was identified. We determined the cDNA sequence of the human orthologue of this gene, MUC13, which localizes to chromosome band 3q13.3 and generates 3.2-kilobase pair transcripts encoding a 512-amino acid protein comprised of an N-terminal mucin repeat domain, three epidermal growth factor-like sequences, a SEA module, a transmembrane domain, and a cytoplasmic tail (GenBank(TM) accession no. AF286113), MUC13 mRNA is expressed most highly in the large intestine and trachea, and at moderate levels in the kidney, small intestine, appendix, and stomach, In situ hybridization in murine tissues revealed expression in intestinal epithelial and lymphoid cells. Immunohistochemistry demonstrated the human MUC13 protein on the apical membrane of both columnar and goblet cells in the gastrointestinal tract, as well as within goblet cell thecae, indicative of secretion in addition to presence on the cell surface. MUC13 is cleaved, and the beta -subunit containing the cytoplasmic tail undergoes homodimerization, Including MUC13, there are at least five cell surface mucins expressed in the gastrointestinal tract.

Minimum acceptable standards for digital compression of a fetal ultrasound video-clip

If the Internet could be used as a method of transmitting ultrasound images taken in the field quickly and effectively, it would bring tertiary consultation to even extremely remote centres. The aim of the study was to evaluate the maximum degree of compression of fetal ultrasound video-recordings that would not compromise signal quality. A digital fetal ultrasound videorecording of 90 s was produced, resulting in a file size of 512 MByte. The file was compressed to 2, 5 and 10 MByte. The recordings were viewed by a panel of four experienced observers who were blinded to the compression ratio used. Using a simple seven-point scoring system, the observers rated the quality of the clip on 17 items. The maximum compression ratio that was considered clinically acceptable was found to be 1:50-1:100. This produced final file sizes of 5-10 MByte, corresponding to a screen size of 320 x 240 pixels, running at 15 frames/s. This study expands the possibilities for providing tertiary perinatal services to the wider community.

Interferon-gamma enhances cytotoxic T lymphocyte recognition of endogenous peptide in keratinocytes without lowering the requirement for surface peptide

Keratinocytes expressing the human papillomavirus (HPV) type 16 E7 protein, as a transgene driven by the K14 promoter, form a murine model of HPV-mediated epithelial cancers in humans. Our previous studies have shown that K14E7 transgenic skin grafts onto syngeneic mice are not susceptible to immune destruction despite the demonstrated presence of a strong, systemic CTL response directed against the E7 protein. Consistent with this finding, we now show that cultured, E7 transgenic keratinocytes (KC) express comparable endogenous levels of E7 protein to a range of CTL-sensitive E7-expressing cell lines but are not susceptible to CTL-mediated lysis in vitro . E7 transgenic and non-transgenic KC are susceptible to conventional mechanisms of CTL-mediated lysis, including perforin and Fas/FasL interaction when an excess of exogenous peptide is provided. The concentration of exogenous peptide required to render a cell susceptible to lysis was similar between KC and other conventional CTL targets (e.g. EL-4), despite large differences in H-2D(b) expression at the cell surface. Furthermore, exposure of KC to IFN-gamma increased H-2D(b) expression, but did not substantially alter the exogenous peptide concentration required to sensitize cells for half maximal lysis. In contrast, the lytic sensitivity of transgenic KC expressing endogenous E7 is modestly improved by exposure to IFN-gamma. Thus, failure of CTL to eliminate KC expressing endogenous E7, and by inference squamous tumours expressing E7, may reflect the need for a sustained, local inflammatory environment during the immune effector phase.

On-line analysis of froth surface in coal and mineral flotation using JKFrothCam

The personal computer revolution has resulted in the widespread availability of low-cost image analysis hardware. At the same time, new graphic file formats have made it possible to handle and display images at resolutions beyond the capability of the human eye. Consequently, there has been a significant research effort in recent years aimed at making use of these hardware and software technologies for flotation plant monitoring. Computer-based vision technology is now moving out of the research laboratory and into the plant to become a useful means of monitoring and controlling flotation performance at the cell level. This paper discusses the metallurgical parameters that influence surface froth appearance and examines the progress that has been made in image analysis of flotation froths. The texture spectrum and pixel tracing techniques developed at the Julius Kruttschnitt Mineral Research Centre are described in detail. The commercial implementation, JKFrothCam, is one of a number of froth image analysis systems now reaching maturity. In plants where it is installed, JKFrothCam has shown a number of performance benefits. Flotation runs more consistently, meeting product specifications while maintaining high recoveries. The system has also shown secondary benefits in that reagent costs have been significantly reduced as a result of improved flotation control. (C) 2002 Elsevier Science B.V. All rights reserved.

The Antarctic nemertean Parborlasia corrugatus: an example of an extreme oxyconformer

The Antarctic nemertean worm, Parborlasia corrugatus, exhibits gigantism, reaching at least 100 g, yet lacks any specialised respiratory organs. The diffusion of oxygen into this worm occurs cutaneously. We examined the metabolic rate of P. corrugatus at -1degreesC in response to decreasing ambient PO2. As the PO2 of the water decreased. so did the metabolic rate of P. corrugatus, indicating that this nemertean worm is an extreme example of an oxyconformer. When the water PO2 decreased below about 120 mmHg, the normally short, round worms became elongated and extremely flattened. This behavioural mechanism would allow for an increase in surface area of the skin, thereby facilitating the diffusion of oxygen.

Repeatability of surface EMG variables in the sternocleidomastoid and anterior scalene muscles

In this study we examined the repeatability and reliability of the surface electromyographic (sEMG) signal mean frequency (MNF), average rectified value (ARV) and conduction velocity (CV) measured for the sternocleidomastoid (SCM) and the anterior scalene (AS) muscles in nine healthy volunteers during 15-s isometric cervical flexion contractions at 50% of the maximal voluntary contraction level over 3 non-consecutive days. Repeatability and reliability estimates were obtained for the initial values and rates of change of each sEMG variable by using both the Intraclass Correlation Coefficient (ICC) and the normalised standard error of the mean (nSEM). Results from SCM indicated good levels of repeatability for the initial value and slope of ARV (ICC > 65%). For the AS, high levels of repeatability were identified for the initial value of MNF (ICC > 70%) and the slope of ARV (ICC > 75%). Values of nSEM in the range 2.8-7.2% were obtained for the initial values of MNF and CV for both SCM and AS, indicating clinically acceptable measurement precision. The low value obtained for the nSEM of the initial value of MNF for the AS, in combination with the high ICC, indicates that of all of the variables examined, this variable could offer the best normative index to distinguish between subjects with and without neck pain, and represents the sEMG variable of choice for future evaluation purposes.

Novel miniaturized systems in high-throughput screening

High-throughput screening (HTS) using high-density microplates is the primary method for the discovery of novel lead candidate molecules. However, new strategies that eschew 2D microplate technology, including technologies that enable mass screening of targets against large combinatorial libraries, have the potential to greatly increase throughput and decrease unit cost. This review presents an overview of state-of-the-art microplate-based HTS technology and includes a discussion of emerging miniaturized systems for HTS. We focus on new methods of encoding combinatorial libraries that promise throughputs of as many as 100 000 compounds per second.

Monitoring the composition and form of urban environments based on the vegetation-impervious surface-soil (VIS) model by sub-pixel analysis techniques

The majority of the world's population now resides in urban environments and information on the internal composition and dynamics of these environments is essential to enable preservation of certain standards of living. Remotely sensed data, especially the global coverage of moderate spatial resolution satellites such as Landsat, Indian Resource Satellite and Systeme Pour I'Observation de la Terre (SPOT), offer a highly useful data source for mapping the composition of these cities and examining their changes over time. The utility and range of applications for remotely sensed data in urban environments could be improved with a more appropriate conceptual model relating urban environments to the sampling resolutions of imaging sensors and processing routines. Hence, the aim of this work was to take the Vegetation-Impervious surface-Soil (VIS) model of urban composition and match it with the most appropriate image processing methodology to deliver information on VIS composition for urban environments. Several approaches were evaluated for mapping the urban composition of Brisbane city (south-cast Queensland, Australia) using Landsat 5 Thematic Mapper data and 1:5000 aerial photographs. The methods evaluated were: image classification; interpretation of aerial photographs; and constrained linear mixture analysis. Over 900 reference sample points on four transects were extracted from the aerial photographs and used as a basis to check output of the classification and mixture analysis. Distinctive zonations of VIS related to urban composition were found in the per-pixel classification and aggregated air-photo interpretation; however, significant spectral confusion also resulted between classes. In contrast, the VIS fraction images produced from the mixture analysis enabled distinctive densities of commercial, industrial and residential zones within the city to be clearly defined, based on their relative amount of vegetation cover. The soil fraction image served as an index for areas being (re)developed. The logical match of a low (L)-resolution, spectral mixture analysis approach with the moderate spatial resolution image data, ensured the processing model matched the spectrally heterogeneous nature of the urban environments at the scale of Landsat Thematic Mapper data.

Boundary-layer transition measurements in hypervelocity flows in a shock tunnel

Experiments to investigate the transition process in hypervelocity boundary layers were performed in the T4 free-piston shock tunnel. An array of thin-film heat-transfer gauges was used to detect the location and extent of the transitional region on a 1500 mm long x 120 turn wide flat plate, which formed one of the walls of a duct. The experiments were performed in a Mach 6 flow of air with 6- and 12-MJ/kg nozzle-supply enthalpies at unit Reynolds numbers ranging from 1.6 x 10(6) to 4.9 x 10(6) m(-1). The results show that the characteristics typical of transition taking place through the initiation, growth, and merger of turbulent spots are evident in the heat-transfer signals. A 2-mm-high excrescence located 440 turn from the leading edge was found to be capable of generating a turbulent wedge within an otherwise laminar boundary layer at a unit Reynolds number of 2.6 x 10(6) m(-1) at the 6-MJ/kg condition. A tripping strip, located 100 mm from the leading edge and consisting of a line 37 teeth of 2 rum height equally spaced and spanning the test surface, was also found to be capable of advancing the transition location at the same condition and at the higher enthalpy condition.