Purcell Enhancement of a Single Silicon Carbide Color Center with Coherent Spin Control.

Silicon carbide has recently been developed as a platform for optically addressable spin defects. In particular, the neutral divacancy in the 4H polytype displays an optically addressable spin-1 ground state and near-infrared optical emission. Here, we present the Purcell enhancement of a single neutral divacancy coupled to a photonic crystal cavity. We utilize a combination of nanolithographic techniques and a dopant-selective photoelectrochemical etch to produce suspended cavities with quality factors exceeding 5000. Subsequent coupling to a single divacancy leads to a Purcell factor of ∼50, which manifests as increased photoluminescence into the zero-phonon line and a shortened excited-state lifetime. Additionally, we measure coherent control of the divacancy ground-state spin inside the cavity nanostructure and demonstrate extended coherence through dynamical decoupling. This spin-cavity system represents an advance toward scalable long-distance entanglement protocols using silicon carbide that require the interference of indistinguishable photons from spatially separated single qubits.

Biotic dissolution of autunite under anaerobic conditions: effect of bicarbonates and Shewanella oneidensis MR1 microbial activity.

Uranium is a contaminant of major concern across the US Department of Energy complex that served a leading role in nuclear weapon fabrication for half a century. In an effort to decrease the concentration of soluble uranium, tripolyphosphate injections were identified as a feasible remediation strategy for sequestering uranium in situ in contaminated groundwater at the Hanford Site. The introduction of sodium tripolyphosphate into uranium-bearing porous media results in the formation of uranyl phosphate minerals (autunite) of general formula {X1-2[(UO2)(PO4)]2-1·nH2O}, where X is a monovalent or divalent cation. The stability of the uranyl phosphate minerals is a critical factor that determines the long-term effectiveness of this remediation strategy that can be affected by biogeochemical factors such as the presence of bicarbonates and bacterial activity. The objective of this research was to investigate the effect of bicarbonate ions present in the aqueous phase on Ca-autunite dissolution under anaerobic conditions, as well as the role of metal-reducing facultative bacterium Shewanella oneidensis MR1. The concentration of total uranium determined in the aqueous phase was in direct correlation to the concentration of bicarbonate present in the solution, and the release of Ca, U and P into the aqueous phase was non-stoichiometric. Experiments revealed the absence of an extensive biofilm on autunite surface, while thermodynamic modeling predicted the presence of secondary minerals, which were identified through microscopy. In conclusion, the dissolution of autunite under the conditions studied is susceptible to bicarbonate concentration, as well as microbial presence.

A qualitative study on the breastfeeding experiences of first-time mothers in Vientiane, Lao PDR.

BACKGROUND: The benefits of breastfeeding are well-recognised. The majority of first-time mothers in the Lao People's Democratic Republic however do not follow WHO guidelines of exclusively breastfeeding for the first six months, and less than half breastfeed for two years. UNICEF identified lack of exclusive breastfeeding as the second highest risk factor for under 5 mortality in Lao PDR, closely following lack of skilled delivery care. This study explored the reasons and influences behind first-time mothers' breastfeeding practices, as well as the role of attitudes, beliefs and experiences in influencing those practices. METHODS: A qualitative research design was chosen for this exploratory study. Two districts in Vientiane were selected, and in each district four focus group discussions, two with six first-time mothers and two with health staff were undertaken. In addition, sixteen in-depth interviews with first-time mothers and seven individual key informants were conducted. RESULTS: Participants demonstrated positive attitudes towards breastfeeding and recognised its importance. Despite this, breastfeeding practices were suboptimal. Few exclusively breastfed for the first six months of the baby's life and most of the first-time mothers included in the sample had stopped or planned to stop breastfeeding by the time the infant was 18 months of age. Work was named as one of the main reasons for less than ideal breastfeeding practices. Traditional beliefs and advice from health staff and the first-time mothers' own mothers, were important influences on breastfeeding practices. First-time mothers also cited experiencing tension when there were differences in advice they received from different people. CONCLUSION: Overall, the mothers were well-informed on the benefits of breastfeeding, and displayed positive attitudes towards it. Nevertheless, few maintained optimal breastfeeding practices in the first two years of the infant's life. Further effort needs to be directed at addressing knowledge and non-knowledge barriers to optimal breastfeeding practices. Of particular importance is working with employers, developing supportive employment policies, providing postnatal support and working with lay people and health professionals. Research is also needed to identify the optimal combination of interventions to promote good breastfeeding practices.

Proteomic and targeted qPCR analyses of subsurface microbial communities for presence of methane monooxygenase.

The Test Area North (TAN) site at the Idaho National Laboratory near Idaho Falls, ID, USA, sits over a trichloroethylene (TCE) contaminant plume in the Snake River Plain fractured basalt aquifer. Past observations have provided evidence that TCE at TAN is being transformed by biological natural attenuation that may be primarily due to co-metabolism in aerobic portions of the plume by methanotrophs. TCE co-metabolism by methanotrophs is the result of the broad substrate specificity of microbial methane monooxygenase which permits non-specific oxidation of TCE in addition to the primary substrate, methane. Arrays of experimental approaches have been utilized to understand the biogeochemical processes driving intrinsic TCE co-metabolism at TAN. In this study, aerobic methanotrophs were enumerated by qPCR using primers targeting conserved regions of the genes pmoA and mmoX encoding subunits of the particulate MMO (pMMO) and soluble MMO (sMMO) enzymes, respectively, as well as the gene mxa encoding the downstream enzyme methanol dehydrogenase. Identification of proteins in planktonic and biofilm samples from TAN was determined using reverse phase ultra-performance liquid chromatography (UPLC) coupled with a quadrupole-time-of-flight (QToF) mass spectrometer to separate and sequence peptides from trypsin digests of the protein extracts. Detection of MMO in unenriched water samples from TAN provides direct evidence of intrinsic methane oxidation and TCE co-metabolic potential of the indigenous microbial population. Mass spectrometry is also well suited for distinguishing which form of MMO is expressed in situ either soluble or particulate. Using this method, pMMO proteins were found to be abundant in samples collected from wells within and adjacent to the TCE plume at TAN.