Different formation kinetics and photoisomerization behavior of self-assembled monolayers of thiols and dithiolanes bearing azobenzene moieties

Self-assembled monolayers (SAMs) containing azobenzene moieties are very attractive for a wide range of applications, including molecular electronics and photonics, bio-interface engineering and sensoring. However, very little is known about the aggregation and photoswitching behavior that azobenzene units undergo during the SAM formation process. Here, we demonstrate that the formation of thiol based SAMs containing azobenzenes (denoted as AzoSH) on gold surfaces is characterised by a two step adsorption kinetics, while a three-step assembly process has been identified for dithiolane-based SAMs containing azobenzenes (denoted AzoSS). The H-aggregation on the AzoSS SAMs was found to be remarkably dependent on the time of self-assembly, with less aggregation as a function of time. While photoisomerization of the AzoSH was suppressed for all different assembly times, the reversible trans–cis photoisomerization of AzoSS SAMs formed over 24 hours was clearly observed upon alternating UV and Vis light irradiation. We contend that detailed information on formation kinetics and related optical properties is of crucial importance for elucidating the photoswitching capabilities of azobenzene based SAMs

Defects of mitochondrial RNA turnover lead to the accumulation of double-stranded RNA in vivo

The RNA helicase SUV3 and the polynucleotide phosphorylase PNPase are involved in the degradation of mitochondrial mRNAs but their roles in vivo are not fully understood. Additionally, upstream processes, such as transcript maturation, have been linked to some of these factors, suggesting either dual roles or tightly interconnected mechanisms of mitochondrial RNA metabolism. To get a better understanding of the turn-over of mitochondrial RNAs in vivo, we manipulated the mitochondrial mRNA degrading complex in Drosophila melanogaster models and studied the molecular consequences. Additionally, we investigated if and how these factors interact with the mitochondrial poly(A) polymerase, MTPAP, as well as with the mitochondrial mRNA stabilising factor, LRPPRC. Our results demonstrate a tight interdependency of mitochondrial mRNA stability, polyadenylation and the removal of antisense RNA. Furthermore, disruption of degradation, as well as polyadenylation, leads to the accumulation of double-stranded RNAs, and their escape out into the cytoplasm is associated with an altered immune-response in flies. Together our results suggest a highly organised and inter-dependable regulation of mitochondrial RNA metabolism with far reaching consequences on cellular physiology

ANGEL2 phosphatase activity is required for non-canonical mitochondrial RNA processing.

Canonical RNA processing in mammalian mitochondria is defined by tRNAs acting as recognition sites for nucleases to release flanking transcripts. The relevant factors, their structures, and mechanism are well described, but not all mitochondrial transcripts are punctuated by tRNAs, and their mode of processing has remained unsolved. Using Drosophila and mouse models, we demonstrate that non-canonical processing results in the formation of 3\u27 phosphates, and that phosphatase activity by the carbon catabolite repressor 4 domain-containing family member ANGEL2 is required for their hydrolysis. Furthermore, our data suggest that members of the FAST kinase domain-containing protein family are responsible for these 3\u27 phosphates. Our results therefore propose a mechanism for non-canonical RNA processing in metazoan mitochondria, by identifying the role of ANGEL2

Myoglobinopathy is an adult-onset autosomal dominant myopathy with characteristic sarcoplasmic inclusions

Myoglobin, encoded by MB, is a small cytoplasmic globular hemoprotein highly expressed in cardiac myocytes and oxidative skeletal myofibers. Myoglobin binds O-2, facilitates its intracellular transport and serves as a controller of nitric oxide and reactive oxygen species. Here, we identify a recurrent c.292C>T ( p.His98Tyr) substitution in MB in fourteen members of six European families suffering from an autosomal dominant progressive myopathy with highly characteristic sarcoplasmic inclusions in skeletal and cardiac muscle. Myoglobinopathy manifests in adulthood with proximal and axial weakness that progresses to involve distal muscles and causes respiratory and cardiac failure. Biochemical characterization reveals that the mutant myoglobin has altered O-2 binding, exhibits a faster heme dissociation rate and has a lower reduction potential compared to wild-type myoglobin. Preliminary studies show that mutant myoglobin may result in elevated superoxide levels at the cellular level. These data define a recognizable muscle disease associated with MB mutation.Peer reviewe

Chief S.O. Alonge: Photographer to the Royal Court of Benin, Nigeria

“Chief S.O. Alonge: Photographer to the Royal Court of Benin, Nigeria” explores several overlapping historical relationships: between colonialism, postcolonialism, and photography; between the medium of photography and classic Benin Kingdom metal plaques and hip ornaments; and between photography as a mode of documenting and constituting interior domestic life and photography as a technology of royal ritual action. The exhibition emerges out of a collection of 3,000 images, including many glass plates and silver gelatin prints by Chief Solomon Osagie Alonge, the first official photographer to the royal court of Benin, now housed at the Eliot Elisofon Photographic Archives at the National Museum of African Art. The photographs are juxtaposed with works drawn from the Museum\u27s significant collection of classic Benin art

Ultrasonic Evaluation of Transient Liquid Phase Bonding in Single Crystal Superalloy Castings

Transient liquid phase bonding (TLPB) is an effective means for joining high performance metal components. It differs from welding and conventional brazing in that it produces very little chemical segregation or microstructural demarcation at the bond-line. The method of transient liquid phase bonding was originally developed in the 1970’s [1] and has been used in the joining of titanium and nickel based superalloy components. In this method, a bonding alloy containing a melting point suppressing element is sandwiched between the parent metals to be joined. The temperature is raised to a point where the bonding alloy melts but the parent metals remain solid. The melting point suppressing element then diffuses away from the bondline, thus raising the melting point and solidifying the bond. Since the temperature never exceeds the melting point of the parent metal, single crystals may be joined without destroying their crystalline structure.</p

PVP2010-25736 SIMULATION AND MEASUREMENT OF THROUGH-WALL RESIDUAL STRESSES IN A STRUCTURAL WELD OVERLAID PRESSURIZER NOZZLE

ABSTRACT Full structural weld overlays (FSWOLs) have been used extensively as a repair/mitigation technique for primary water stress corrosion cracking (PWSCC) in pressurizer nozzle dissimilar metal (DM) welds. To support an approved FSWOL design and safety submission for British Energy pressurized water reactor (PWR) nozzles, an in-depth evaluation was performed to assess the effects of a FSWOL on the throughwall residual stress distribution in safety/relief pressurizer nozzles. Two safety/relief pressurizer nozzle mockups were fabricated based on British Energy&apos;s PWR nozzle design. One mockup included the nozzle to safe-end DM weld and the safe-end to stainless steel weld while the second mockup included the DM weld, the stainless steel weld and a Westinghouse-designed structural weld overlay. The mockups were fabricated utilizing materials and techniques that represented the plant-specific nozzles as closely as possible and detailed welding parameters were recorded during fabrication. All welds were subsequently nondestructively evaluated (NDE). A thorough review of the detailed fabrication records and the NDE results was performed and several circumferential positions were selected on each mockup for subsequent residual stress measurement. The through-wall residual stress profiles were experimentally measured through the DM weld centerline at the selected circumferential positions using both the deep hole drilling (DHD) and incremental deep hole drilling (iDHD) measurement techniques. In addition to experimental residual stress measurements, the through-wall residual stress profiles were simulated using a 2-D axisymmetric ANSYS™ finite element (FE) model. The model utilized kinematic strain hardening and the temperature constraint method which greatly simplified the simulation as compared to detailed heat source modeling methods. A range of residual weld stress profiles was calculated by varying the time at which the temperature constraints were applied to the model. The simulation results were compared to the measurement results. It was found that the effects of the FSWOL were principally three fold. Specifically, the FSWOL causes a much deeper compressive stress field, i.e., the overlay shifts tension out towards the outside diameter surface. Further, the FSWOL reduces tension in the underlying dissimilar metal weld, and finally, the FSWOL causes higher peak compressive and tensile residual stresses, both of which move deeper into the nozzle wall after the overlay is applied. Relatively good agreement was observed between the FE results and the measurements results. BACKGROUND The project involved multi-disciplinary team members from British Energy

Visual and phonological pathways to the lexicon: Evidence from Chinese readers

In this study, we investigated the role of visual and phonological information in lexical access of Chinese characters. Homophonic English words have been the main source of stimuli for word recognition research. However, since these stimuli also often look alike, visual and phonological information may be confounded in reported experiment. In contrast, many homophonic Chinese characters are visually distinct. In addition, visually similar characters often have very different pronunciations. These characteristics allow a more controlled investigation of the roles of visual and phonological information in activation of meaning. In the present study, two types of Chinese characters were used in a semantic categorization paradigm: integrated characters, which contain strokes that are not separable; and compound characters, which contain at least two clearly identifiable components. The results show that the recognition of a Chinese integrated character depends primarily on visual information, whereas the recognition of a Chinese compound character relies on visual, phonological, and semantic information. It is concluded that visual information plays a greater role in Chinese character recognition than has previously been documented.link_to_subscribed_fulltex