Design and characterisation of a single-reflection,solid-state detector with high discrimination against backscattered electrons for cathodoluminescence microscopy

Aportable solid-state detector (SSD) for cathodoluminescence (CL) has been constructed and tested. The detector geometry utilises a parabolic reflector to direct light towards the solid-state detection element. The photo-sensitive area of the solid-state photodiodes is situated at a level in line with or sightly below the top surface of the specimen to minimise the collection of backscattered electrons (BSEs) coming directly from the beam impact point. The components have been integrated into a single unit to enhance portability. In comparison with a commercial CL detection system, the new geometry shows excellent efficiency in rejecting BSE contribution during CL operation. A light collection solid angle close to 1.97π steradian is realised in this geometry, higher than other SSD-CL systems. A method for characterising CL detection system performance has been developed.     

Influence of joint eccentricity and rigidity on the load capacity of a space truss sub-assemblage

Experimental testing of bolted and welded space truss sub-assemblages with large joint eccentricities has displayed satisfactory performance. Tests have been carried out on five sub-assemblages from a double layer (plate-like) space truss configuration. The distinctive features of the configuration employed were chord member continuity and the resulting large joint eccentricities. The particular layout adopted furnished orthotropic behaviour for stiffness and strength, so two sub-assemblage configurations were adopted. To provide control and comparisons a welded concentrically jointed sub-assemblage was tested in addition to the bolted and welded sub-assemblages. Although the large joint eccentricities reduced sub-assemblages stiffness and peak load capacity, the continuity of chords largely offset these reductions even when bolted joint details were used; for the welded joint cases peak load capacities were at least 50 per cent higher again. The stiffness of such systems is seen to be sensitive to member and joint imperfections, and joint slip.     

Low-Coverage Whole Genome Sequencing Using Laser Capture Microscopy with Combined Digital Droplet PCR: An Effective Tool to Study Copy Number and Kras Mutations in Early Lung Adenocarcinoma Development

Defining detailed genomic characterization of early tumor progression is critical to identifying key regulators and pathways in carcinogenesis as potentially druggable targets. In human lung cancer, work to characterize early cancer development has mainly focused on squamous cancer, as the earliest lesions are more proximal in the airways and often accessible by repeated bronchoscopy. Adenocarcinomas are typically located distally in the lung, limiting accessibility for biopsy of pre-malignant and early stages. Mouse lung cancer models recapitulate many human genomic features and provide a model for tumorigenesis with pre-malignant atypical adenomatous hyperplasia and in situ adenocarcinomas often developing contemporaneously within the same animal. Here, we combined tissue characterization and collection by laser capture microscopy (LCM) with digital droplet PCR (ddPCR) and low-coverage whole genome sequencing (LC-WGS). ddPCR can be used to identify specific missense mutations in Kras (Kirsten rat sarcoma viral oncogene homolog, here focused on Kras Q61) and estimate the percentage of mutation predominance. LC-WGS is a cost-effective method to infer localized copy number alterations (CNAs) across the genome using low-input DNA. Combining these methods, the histological stage of lung cancer can be correlated with appearance of Kras mutations and CNAs. The utility of this approach is adaptable to other mouse models of human cancer.     

Anticonvulsants and congenital malformations

Earlier studies indicated that the prevalence of congenital anomalies is greater in infants of epileptic mothers treated with anticonvulsants than in infants of mothers without epilepsy. We carried out a study of women in the General Practice Research Database who delivered liveborn infants between January 1988 and March 1993 and who were exposed to an anticonvulsant drug during the first trimester of pregnancy, and women with epilepsy not treated with anticonvulsants during pregnancy. We matched two nonexposed women without epilepsy to each exposed woman for age at delivery, date of baby's birth, and general practice. Two hundred ninety-seven women treated for epilepsy had 10 liveborn infants with major anomalies (3.4%) compared with 6 of the 594 nonexposed women (1.0%, RR = 3.3, 95% CI 1.2-9.2). We conclude that the infants of women with epilepsy who are treated with an anticonvulsant during the first trimester of pregnancy have an increased risk of major congenital anomalies.     

Front- and backside investigations of thermal and electronic properties of semiconducting devices

Shrinking feature sizes of electronic devices are leading to an increase of the internal electrical fields resulting in an increased hot electron generation. Consequently, the investigation of the resulting electrical device degradation and breakdown mechanisms gain in significance. A powerful tool for these investigations is the photon emission microscope (PEM). A disadvantage of this technique, however, is the inability to image radiative recombination processes which are taking place underneath metallization layers. In this paper, we will show that PEM investigations from the backside overcome problems of failure localization caused by opaque metal contacts. A further scope of this work is to compare the information which is obtained by collecting the emitted light with thermal properties like failure induced hot spots inside a device. This thermal characterization is carried out with a scanning thermal microscope (SThM), which is used for the localization of failures in integrated devices and for backside measurements on thinned substrates.     

Intensifying Heat Using MOF-Isolated Graphene for Solar-Driven Seawater Desalination at 98% Solar-to-Thermal Efficiency

Photothermal materials are crucial for diverse heating applications, but it remains challenging to achieve high energy conversion efficiency due to the difficulty to concurrently improve light absorbance and suppress heat loss. Herein, a zeolitic imidazolate framework-isolated graphene (G@ZIF) nanohybrid is demonstrated that utilizes ultrathin, heat-insulating ZIF layers, and G@ZIF interfacial nanocavity to synergistically intensify light absorbance and heat localization. Under artificial sunlight illumination (≈1 kW m⁻²), the G@ZIF film attains a maximum temperature of 120 °C in an open environment with a 98% solar-to-thermal conversion efficiency. Importantly, the porous ZIF layer allows small molecules/media to enter and access the embedded hot graphene surface for targeted heat transfer in practical applications. As a proof-of-concept, the G@ZIF-based steam generator realizes 96% energy conversion from light to vapor with near-perfect desalination and water purification efficiencies (>99.9%). This design is generic and can be extended to other photothermal systems for advanced solar-thermal applications, including catalysis, water treatments, sterilization, and mechanical actuation.     

A portable scanning electron microscope column design based on the use of permanent magnets

A portable scanning electron microscope (SEM) column design is presented which makes use of permanent magnets. Simulation results predict that such an SEM column is feasible and that it can be compact. The column height is typically less than 12 cm. The column is designed to be modular, so that it can fit onto a wide range of different specimen chamber types, and can also be readily replaced.     

Random amplified polymorphic DNA (RAPD) fingerprints for identification of red meat animal species

The random amplified polymorphic DNA (RAPD) method was used to generate fingerprint patterns for 10 meat species: wild boar, pig, horse, buffalo, beef, venison, dog, cat, rabbit and kangaroo. A total of 29 10-nucleotide primers, with GC contents ranging from 50–80%, were evaluated for their specificity and efficiency. The fingerprint patterns that were generated were found in some cases to be species-specific, i.e. one species could be differentiated from another. The advantages and disadvantages of using RAPD-PCR for the identification of red meat species are also discussed.     

Fluorescein analogues inhibit SecA ATPase: the first sub-micromolar inhibitor of bacterial protein translocation

SecA is a central component of the general secretion system that is essential for bacterial growth and thus an ideal target for antimicrobial agents. A series of fluorescein analogues were first screened against the ATPase activity using the truncated unregulated SecA catalytic domain. Rose bengal (RB) and erythrosin B (EB) were found to be potent inhibitors SecA with IC(50) values of 0.5 μM and 2 μM, respectively. RB and EB inhibit the catalytic SecA ATPase more effectively than the F(1) F(0) -proton ATPase. We used three assays to test the effect of these compounds on full-length SecA ATPase: in solution (intrinsic ATPase), in membrane preparation, and translocation ATPase. RB and EB show the following trend in terms of IC(50) values: translocation ATPase相似文献   

Morphology and melt rheology of nylon 11/clay nanocomposites

Nylon 11 (PA11)/clay nanocomposites have been prepared by melt‐blending, followed by melt‐extrusion through a capillary. Transmission electron microscopy shows that the exfoliated clay morphology is dominant for low nanofiller content, while the intercalated one is prevailing for high filler loading. Melt rheological properties of PA11 nanocomposites have been studied in both linear and nonlinear viscoelastic response regions. In the linear regime, the nanocomposites exhibit much higher storage modulus (G′) and loss modulus (G″) values than neat PA11. The values of G′ and G″ increase steadily with clay loading at low concentrations, while the G′ and G″ for the sample with 5 wt % clay show an inverse dependence and lie between the modulus values of the samples with 1 and 2 wt % of clay. This is attributed to the alignment/orientation of nanoclay platelets in the intercalated nanocomposite induced by capillary extrusion. In the nonlinear regime, the nanocomposites show increased shear viscosities when compared with the neat resin. The dependence of the shear viscosity on clay loading has analogous trend to that of G′ and G″. Finally, a comparison has been made between the complex and steady viscosities to verify the applicability of the empirical Cox‐Merz rule. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 542–549, 2006