Impact of Short-Range Scattering on the Metallic Transport of Strongly Correlated 2D Holes in GaAs Quantum Wells

Understanding the non-monotonic behavior in the temperature dependent resistance, R(T), of strongly correlated two-dimensional (2D) carriers in clean semiconductors has been a central issue in the studies of 2D metallic states and metal-insulator-transitions. We have studied the transport of high mobility 2D holes in 20nm wide GaAs quantum wells (QWs) with varying short-range disorder strength by changing the Al fraction x in the Al_xGa_{1-x}As barrier. Via varying the short range interface roughness and alloy scattering, it is observed that increasing x suppresses both the strength and characteristic temperature scale of the 2D metallicity, pointing to the distinct role of short-range versus long-range disorder in the 2D metallic transport in this correlated 2D hole system with interaction parameter r_s~ 20.Comment: accepted for publication in Phys Rev

Anisotropic electrical resistance in mesoscopic LaAlO 3 /SrTiO 3 devices with individual domain walls

International audienceThe crystal structure of bulk SrTiO 3 (STO) transitions from cubic to tetragonal at around 105 K. Recent local scanning probe measurements of LaAlO 3 /SrTiO 3 (LAO/STO) interfaces indicated the existence of spatially inhomogeneous electrical current paths and electrostatic potential associated with the structural domain formation in the tetragonal phase of STO. Here we report a study of temperature dependent electronic transport in combination with the polarized light microscopy of structural domains in mesoscopic LAO/STO devices. By reducing the size of the conductive interface to be comparable to that of a single tetragonal domain of STO, the anisotropy of interfacial electron conduction in relationship to the domain wall and its direction was characterized between T = 10–300 K. It was found that the four-point resistance measured with current parallel to the domain wall is larger than the resistance measured perpendicular to the domain wall. This observation is qualitatively consistent with the current diverting effect from a more conductive domain wall within the sample. Among all the samples studied, the maximum resistance ratio found is at least 10 and could be as large as 10 5 at T = 10 K. This electronic anisotropy may have implications on other oxide hetero-interfaces and the further understanding of electronic/magnetic phenomena found in LAO/STO

Intrinsic Electron Mobility Exceeding 10³ cm²/(V s) in Multilayer InSe FETs

Graphene-like two-dimensional (2D) materials not only are interesting for their exotic electronic structure and fundamental electronic transport or optical properties but also hold promises for device miniaturization down to atomic thickness. As one material belonging to this category, InSe, a III–VI semiconductor, not only is a promising candidate for optoelectronic devices but also has potential for ultrathin field effect transistor (FET) with high mobility transport. In this work, various substrates such as PMMA, bare silicon oxide, passivated silicon oxide, and silicon nitride were used to fabricate multilayer InSe FET devices. Through back gating and Hall measurement in four-probe configuration, the device’s field effect mobility and intrinsic Hall mobility were extracted at various temperatures to study the material’s intrinsic transport behavior and the effect of dielectric substrate. The sample’s field effect and Hall mobilities over the range of 20–300 K fall in the range of 0.1–2.0 × 10³ cm²/(V s), which are comparable or better than the state of the art FETs made of widely studied 2D transition metal dichalcogenides

SYNBIOCHEM - A SynBio foundry for the biosynthesis and sustainable production of fine and speciality chemicals.

The Manchester Synthetic Biology Research Centre (SYNBIOCHEM) is a foundry for the biosynthesis and sustainable production of fine and speciality chemicals. The Centre's integrated technology platforms provide a unique capability to facilitate predictable engineering of microbial bio-factories for chemicals production. An overview of these capabilities is described

Comparison of the Genome Sequence of the Poultry Pathogen Bordetella avium with Those of B. bronchiseptica, B. pertussis, and B. parapertussis Reveals Extensive Diversity in Surface Structures Associated with Host Interaction

Bordetella avium is a pathogen of poultry and is phylogenetically distinct from Bordetella bronchiseptica, Bordetella pertussis, and Bordetella parapertussis, which are other species in the Bordetella genus that infect mammals. In order to understand the evolutionary relatedness of Bordetella species and further the understanding of pathogenesis, we obtained the complete genome sequence of B. avium strain 197N, a pathogenic strain that has been extensively studied. With 3,732,255 base pairs of DNA and 3,417 predicted coding sequences, it has the smallest genome and gene complement of the sequenced bordetellae. In this study, the presence or absence of previously reported virulence factors from B. avium was confirmed, and the genetic bases for growth characteristics were elucidated. Over 1,100 genes present in B. avium but not in B. bronchiseptica were identified, and most were predicted to encode surface or secreted proteins that are likely to define an organism adapted to the avian rather than the mammalian respiratory tracts. These include genes coding for the synthesis of a polysaccharide capsule, hemagglutinins, a type I secretion system adjacent to two very large genes for secreted proteins, and unique genes for both lipopolysaccharide and fimbrial biogenesis. Three apparently complete prophages are also present. The BvgAS virulence regulatory system appears to have polymorphisms at a poly(C) tract that is involved in phase variation in other bordetellae. A number of putative iron-regulated outer membrane proteins were predicted from the sequence, and this regulation was confirmed experimentally for five of these

SYNBIOCHEM Design-Build-Test-Learn pipeline

Quantified titers and peak values measured through different rounds of the SYNBIOCHEM Design-Build-Test-Learn (DBTL) pipeline for microbial production of fine chemicals. The pipeline was applied for the production of flavonoids and alkaloids in Escherichia coli. The flavonoids data contains cinnamate and (2S)-pinocembrin measurements for combinatorial libraries for: a) DBT round 1; b) DBT round 2; c) Chassis selection; d) Media screening; e) Optimization. The alkaloids data provides (S)-reticuline and (S)-scoulerine measurements for a combinatorial library corresponding to one DBTL round