gem-Dibromocyclopropanes and enzymatically derived cis-1,2-dihydrocatechols as building blocks in alkaloid synthesis

The application of the title building blocks, the 6,6-dibromobicyclo[3.1.0]hexanes and the cis-1,2-dihydrocatechols, to the total synthesis of crinine and lycorinine alkaloids is described.We thank the Australian Research Council and the Institute of Advanced Studies for generous financial support

Semi-classical States in Homogeneous Loop Quantum Cosmology

Semi-classical states in homogeneous loop quantum cosmology (LQC) are constructed by two different ways. In the first approach, we firstly construct an exponentiated annihilation operator. Then a kind of semi-classical (coherent) state is obtained by solving the eigen-equation of that operator. Moreover, we use these coherent states to analyze the semi-classical limit of the quantum dynamics. It turns out that the Hamiltonian constraint operator employed currently in homogeneous LQC has correct classical limit with respect to the coherent states. In the second approach, the other kind of semi-classical state is derived from the mathematical construction of coherent states for compact Lie groups due to Hall.Comment: 13 pages, submitted to CQ

Alternative quantization of the Hamiltonian in loop quantum cosmology II: Including the Lorentz term

Since there are quantization ambiguities in constructing the Hamiltonian constraint operator in isotropic loop quantum cosmology, it is crucial to check whether the key features of loop quantum cosmology are robust against the ambiguities. In this paper, we quantize the Lorentz term of the gravitational Hamiltonian constraint in the spatially flat FRW model by two approaches different from that of the Euclidean term. One of the approaches is very similar to the treatment of the Lorentz part of Hamiltonian in loop quantum gravity and hence inherits more features from the full theory. Two symmetric Hamiltonian constraint operators are constructed respectively in the improved scheme. Both of them are shown to have the correct classical limit by the semiclassical analysis. In the loop quantum cosmological model with a massless scalar field, the effective Hamiltonians and Friedmann equations are derived. It turns out that the classical big bang is again replaced by a quantum bounce in both cases. Moreover, there are still great possibilities for the expanding universe to recollapse due to the quantum gravity effect.Comment: 8 pages, 2 figure

Manipulating the enone moiety of levoglucosenone: 1,3-Transposition reactions including ones leading to isolevoglucosenone

This research was part-funded by Circa Group Pty Ltd

Movement of Atrazine and Nitrate in Sharkey Clay Soil: Evidence of Preferential Flow (Bulletin #846)

Incidence of groundwater contamination by agrichemicals in the United States and elsewhere is of concern in terms of the health effects associated with chemical contaminants present in drinking water. The major objectives of this study were: (1) to quantify the mobility of atrazine and nitrates in a Sharkey clay soil in the presence of a shallow water table, and (2) to determine evidence of preferential flow patterns on the mobility of agricultural chemicals in such soils.https://digitalcommons.lsu.edu/agcenter_bulletins/1016/thumbnail.jp

Developmental Analysis of Mimulus Seed Transcriptomes Reveals Functional Gene Expression Clusters and Four Imprinted, Endosperm-Expressed Genes

The double fertilization of the female gametophyte initiates embryogenesis and endosperm development in seeds via the activation of genes involved in cell differentiation, organ patterning, and growth. A subset of genes expressed in endosperm exhibit imprinted expression, and the correct balance of gene expression between parental alleles is critical for proper endosperm and seed development. We use a transcriptional time series analysis to identify genes that are associated with key shifts in seed development, including genes associated with secondary cell wall synthesis, mitotic cell cycle, chromatin organization, auxin synthesis, fatty acid metabolism, and seed maturation. We relate these genes to morphological changes in Mimulus seeds. We also identify four endosperm-expressed transcripts that display imprinted (paternal) expression bias. The imprinted status of these four genes is conserved in other flowering plants, suggesting that they are functionally important in endosperm development. Our study explores gene regulatory dynamics in a species with ab initio cellular endosperm development, broadening the taxonomic focus of the literature on gene expression in seeds. Moreover, it is the first to validate genes with imprinted endosperm expression in Mimulus guttatus, and will inform future studies on the genetic causes of seed failure in this model system

Physical representation of hillslope leaky barriers in 2D hydraulic models: A case study from the Calder Valley

The resources of small-scale community-based flood risk action groups are often limited, hence studies to model and predict the effects of Natural Flood Management are often restrained by time and lack of empirical data to validate results. As a result, representations of hillslope leaky barriers are largely modelled as several equifinal approaches, often without survey data. The geometrical characteristics of hillslope leaky barriers were surveyed for the first time at Hardcastle Crags, Calder Valley. This data informed six 2D hydraulic model representation scenarios with varying combinations of topography modification and roughness increase, allowing the sensitivity of their results to be tested. Results from Scenario 3 (topography modification and roughness increase) estimated total hillslope runoff peak flow to reduce by 16.6% in a 1:1-year design return period; however, this reduction diminished as rainfall intensity increased. Return periods of over 1:30 year estimated peak flow reductions of <5%. Only 14.3%–21.7% (98–148 m3) of the total additional storage provided by the barriers is mobilised during simulated events. A multi-peaked rainfall event from December 2015 was also simulated. Although the initial peak flow was reduced by 22.7%, as storage became mobilised, effectiveness reduced significantly for subsequent peaks within the same event

Association between Diagnosed Anxiety and Depression and Exposure to Life Stressors during the COVID-19 Pandemic

Research suggests that mental health disorders heighten the risk of exposure to life stressors. Drawing on a sample of 754 adults from a survey distributed at six primary care clinics, we examine whether adults who reported ever being diagnosed with depression or anxiety were more likely to experience an employment disruption, a housing disruption, and/or report more COVID-19-related stressors during the COVID-19 pandemic. Individuals who reported ever being diagnosed with depression reported a greater burden (B=.75) of COVID-19-related stressors. Those who reported ever being diagnosed with anxiety had higher odds of experiencing an employment disruption (OR=1.90) and a housing disruption (OR=2.92) and reported about one (B=.97) additional COVID-19-related stressor. Our results suggest that the COVID-19 pandemic may have deepened existing mental health disparities by exposing those with a depression or anxiety diagnosis to additional life stressors

Correlating Agricultural Use of Organophosphates with Outdoor Air Concentrations: A Particular Concern for Children

For the organophosphate pesticide chlorpyrifos, median inhalation noncancer, acute children’s exposures in agricultural communities are elevated above reference doses; for diazinon, similar exposures are nearly elevated. We used multivariate linear regression analysis to examine the temporal and spatial associations between agricultural use and measured air concentrations of chlorpyrifos, chlorpyrifos oxon, diazinon, and malathion. Agricultural use within a 3-mile radius on the monitoring day and use on the 2–4 prior days were significantly associated with air concentrations (p < 0.01) for all analytes except malathion; chlorpyrifos oxon showed the strongest association (p < 0.0001). In the final models, which included weather parameters, the proportion of variance (r (2), adjusted for the number of model variables) for all analytes ranged from 0.28 (p < 0.01) for malathion to 0.65 (p < 0.0001) for diazinon. Recent cellular, animal, and human evidence of toxicity, particularly in newborns, supports the public health concern indicated by initial risk estimates. Agricultural applications of organophosphates and their oxon products may have substantial volatization and off-field movement and are a probable source of exposures of public health concern