Optical tuning of exciton and trion emissions in monolayer phosphorene

Monolayer phosphorene provides a unique two-dimensional (2D) platform to investigate the fundamental dynamics of excitons and trions (charged excitons) in reduced dimensions. However, owing to its high instability, unambiguous identification of monolayer phosphorene has been elusive. Consequently, many important fundamental properties, such as exciton dynamics, remain underexplored. We report a rapid, noninvasive, and highly accurate approach based on optical interferometry to determine the layer number of phosphorene, and confirm the results with reliable photoluminescence measurements. Furthermore, we successfully probed the dynamics of excitons and trions in monolayer phosphorene by controlling the photo-carrier injection in a relatively low excitation power range. Based on our measured optical gap and the previously measured electronic energy gap, we determined the exciton binding energy to be ~0.3 eV for the monolayer phosphorene on SiO2/Si substrate, which agrees well with theoretical predictions. A huge trion binding energy of ~100 meV was first observed in monolayer phosphorene, which is around five times higher than that in transition metal dichalcogenide (TMD) monolayer semiconductor, such as MoS2. The carrier lifetime of exciton emission in monolayer phosphorene was measured to be ~220 ps, which is comparable to those in other 2D TMD semiconductors. Our results open new avenues for exploring fundamental phenomena and novel optoelectronic applications using monolayer phosphorene

Manipulation of photoluminescence of two-dimensional MoSe₂ by gold nanoantennas

Monolayer molybdenum diselenide (MoSe₂), a member of the TMDCs family, is an appealing candidate for coupling to gold plasmonic nanostructures as it has smaller bandgap and higher electron mobility in comparison to frequently studied molybdenum disulfide (MoS₂). The PL of MoSe₂ occurs in the near-infrared spectral range where the emissive properties do not suffer from the enhanced dissipation in the gold due to inter-band transitions. Here, we study the interaction between monolayer MoSe₂ and plasmonic dipolar antennas in resonance with the PL emission of MoSe₂. By varying the thickness of the spacer between the MoSe₂ layer and nanoantenna, we demonstrate manipulation of the PL intensity from nearly fourfold quenching to approximately threefold enhancement. Furthermore, we show that the coupled TMDC-nanoantenna system exhibits strong polarization-dependent PL, thus offering the possibility of polarization-based emission control. Our experimental results are supported by numerical simulations as well. To the best of our knowledge, this is the first study of Au-MoSe₂ plasmonic hybrid structures realizing flexible PL manipulation

The emergence and diversification of a zoonotic pathogen from within the microbiota of intensively farmed pigs

The expansion and intensification of livestock production is predicted to promote the emergence of pathogens. As pathogens sometimes jump between species, this can affect the health of humans as well as livestock. Here, we investigate how livestock microbiota can act as a source of these emerging pathogens through analysis of Streptococcus suis, a ubiquitous component of the respiratory microbiota of pigs that is also a major cause of disease on pig farms and an important zoonotic pathogen. Combining molecular dating, phylogeography, and comparative genomic analyses of a large collection of isolates, we find that several pathogenic lineages of S. suis emerged in the 19th and 20th centuries, during an early period of growth in pig farming. These lineages have since spread between countries and continents, mirroring trade in live pigs. They are distinguished by the presence of three genomic islands with putative roles in metabolism and cell adhesion, and an ongoing reduction in genome size, which may reflect their recent shift to a more pathogenic ecology. Reconstructions of the evolutionary histories of these islands reveal constraints on pathogen emergence that could inform control strategies, with pathogenic lineages consistently emerging from one subpopulation of S. suis and acquiring genes through horizontal transfer from other pathogenic lineages. These results shed light on the capacity of the microbiota to rapidly evolve to exploit changes in their host population and suggest that the impact of changes in farming on the pathogenicity and zoonotic potential of S. suis is yet to be fully realized

The emergence and diversification of a zoonotic pathogen from within the microbiota of intensively farmed pigs

The expansion and intensification of livestock production is predicted to promote the emergence of pathogens. As pathogens sometimes jump between species, this can affect the health of humans as well as livestock. Here, we investigate how livestock microbiota can act as a source of these emerging pathogens through analysis of Streptococcus suis, a ubiquitous component of the respiratory microbiota of pigs that is also a major cause of disease on pig farms and an important zoonotic pathogen. Combining molecular dating, phylogeography, and comparative genomic analyses of a large collection of isolates, we find that several pathogenic lineages of S. suis emerged in the 19th and 20th centuries, during an early period of growth in pig farming. These lineages have since spread between countries and continents, mirroring trade in live pigs. They are distinguished by the presence of three genomic islands with putative roles in metabolism and cell adhesion, and an ongoing reduction in genome size, which may reflect their recent shift to a more pathogenic ecology. Reconstructions of the evolutionary histories of these islands reveal constraints on pathogen emergence that could inform control strategies, with pathogenic lineages consistently emerging from one subpopulation of S. suis and acquiring genes through horizontal transfer from other pathogenic lineages. These results shed light on the capacity of the microbiota to rapidly evolve to exploit changes in their host population and suggest that the impact of changes in farming on the pathogenicity and zoonotic potential of S. suis is yet to be fully realized.This work was primarily funded by an EU Horizon 2020 grant “PIGSs” (727966) and a ZELS BBSRC award “Myanmar Pigs Partnership (MPP)” (BB/L018934/1). G.G.R.M., E.L.M., and L.A.W. were supported by a Sir Henry Dale Fellowship to L.A.W. jointly funded by the Wellcome Trust and the Royal Society (109385/Z/15/Z). N.H. was supported by a Challenge grant from the Royal Society (CH16011) and an Isaac Newton Trust Research Grant [17.24(u)]. G.G.R.M. was also supported by a Research Fellowship at Newnham College. S.B. is supported by the Medical Research Council (MR/V032836/1). PIC North America provided part of the funds for the sequencing of the isolates from the USA. A.J.B. and M.M. were funded by Medical Research Council and Biotechnology and Biological Sciences Research Council studentships respectively, and M.M. was co-funded by the Raymond and Beverly Sackler Fund. We would like to acknowledge Susanna Williamson at the APHA for providing samples, Oscar Cabezón for sampling of the wild boar population in Spain, Mark O’Dea for access to sequence data from Australian isolates, the PIGSs and MPP consortiums for providing samples and helpful discussions, Julian Parkhill and John Welch for helpful discussions, and two anonymous reviewers for their valuable suggestions for improving the manuscript. This research was funded in whole or in part by the Wellcome Trust. For the purpose of Open Access, the author has applied a CC BY public copyright license to any Author Accepted Manuscript (AAM) version arising from this submission.info:eu-repo/semantics/publishedVersio

First Report of Lumpy Skin Disease in Myanmar and Molecular Analysis of the Field Virus Isolates

Lumpy skin disease virus (LSDV) causes lumpy skin disease in cattle and buffaloes, which is associated with significant animal production and economic losses. Since the 2000s, LSDV has spread from Africa to several countries in the Middle East; Europe; and Asia; including, more recently, several south-east Asian countries. In November 2020, Myanmar reported its first LSD outbreak. This study reports on the first incursion of LSD in Myanmar and the molecular analysis of the LSDV detected. Staff from the Livestock Breeding and Veterinary Department (LBVD) of the Ministry of Agriculture, Livestock, and Irrigation collected samples from cattle with suspected LSD infection. The Food and Agriculture Organization (FAO) of the United Nations’ Emergency Centre for Transboundary Animal Diseases (ECTAD) and the Joint International Atomic Energy Agency (IAEA)/FAO program’s Animal Health and Production laboratory provided LSDV diagnostic support to two regional veterinary diagnostic laboratories in Myanmar. Samples from 13 cattle tested positive by real-time PCR. Selected samples underwent sequence analysis in IAEA laboratories. The results show that the Myanmar LSDV sequences clustered with LSDV isolates from Bangladesh and India, LSDV Kenya, and LSDV NI-2490. Further characterization showed that the Myanmar LSDV is 100% identical to isolates from Bangladesh and India, implying a common source of introduction. These findings inform diagnosis and development of control strategies

Robust Excitons and Trions in Monolayer MoTe2

Molybdenum telluride (MoTe2) has emerged as a special member in the family of two-dimensional transition metal dichalcogenide semiconductors, owing to the strong spin-orbit coupling and relatively small energy gap, which offers new applications in valleytronic and excitonic devices. Here we successfully demonstrated the electrical modulation of negatively charged (X-), neutral (X0), and positively charged (X+) excitons in monolayer MoTe2 via photoluminescence spectroscopy. The binding energies of X+ and X- were measured to be -24 and -27 meV, respectively.The exciton binding energy of monolayer MoTe2 was measured to be 0.58 ± 0.08 eV via photoluminescence excitation spectroscopy, which matches well with our calculated value of 0.64 eV

Empowering health workers and leveraging digital technology to improve access to mental health and epilepsy care: A longitudinal quasi-experimental study in Hlaing Thar Yar Township

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Haematophagous mites on poultry farms in the Republic of the Union of Myanmar

Haematophagous ectoparasites of poultry, such as Ornithonyssus sylviarum, northern fowl mites (NFMs), Dermanyssus gallinae, poultry red mites (PRMs), and Ornithonyssus bursa, tropical fowl mites (TFMs) are prevalent worldwide. Although poultry farming is a major industry in Southeast Asia, there are only a few reports concerning the prevalence of avian mites in this region. In this study, we sampled twenty farms in four major poultry farming areas in Myanmar. We detected the mites on six farms, and they showed morphological similarities to NFMs and TFMs. The nucleotide sequences of cytochrome c oxidase subunit I indicated that some mites were NFMs. This is the first report confirming the presence of NFMs and TFMs among the hematophagous mites infesting chickens on Myanmar poultry farms