Tuning Pd-nanoparticle@MIL-101(Cr) catalysts for tandem reductive amination

The authors thank the EPSRC (EP/L505079/1), SASOL Technology UK and the University of St Andrews for funding.The versatility of MOFs as highly porous Lewis acidic supports for precious metal nanoparticles has been exploited for one-pot tandem reductive amination catalysis. MIL-101(Cr) loaded with Pd nanoparticles ca. 3 nm in size at 0.2–1 wt% has been used to catalyse the reaction of 4′-fluoroacetophenone with benzylamine under 10 bar of H2 to give the secondary amine, 4′-fluoro-α-methyl-N-phenylmethylbenzenemethanamine. For the highest Pd loading, major hydrogenolysis of the secondary amine occurs in a second tandem reaction, but by changing the ratio of Pd to Lewis acidic Cr3+ active sites it is possible to tune the catalytic selectivity to the desired 2° amine product. An empirical kinetic analysis was performed to demonstrate this active site complementarity.Publisher PDFPeer reviewe

Probing the Density in the Galactic Center Region: Wind-Blown Bubbles and High-Energy Proton Constraints

Recent observations of the Galactic center in high-energy gamma-rays (above 0.1TeV) have opened up new ways to study this region, from understanding the emission source of these high-energy photons to constraining the environment in which they are formed. We present a revised theoretical density model of the inner 5pc surrounding Sgr A* based on the fact that the underlying structure of this region is dominated by the winds from the Wolf-Rayet stars orbiting Sgr A*. An ideal probe and application of this density structure is this high energy gamma-ray emission. We assume a proton-scattering model for the production of these gamma-rays and then determine first whether such a model is consistent with the observations and second whether we can use these observations to further constrain the density distribution in the Galactic center.Comment: 36 pages including 17 figures, submitted to ApJ, comments welcom

Circadian and wakefulness-sleep modulation of cognition in humans

Cognitive and affective processes vary over the course of the 24 h day. Time of day dependent changes in human cognition are modulated by an internal circadian timekeeping system with a near-24 h period. The human circadian timekeeping system interacts with sleep-wakefulness regulatory processes to modulate brain arousal, neurocognitive and affective function. Brain arousal is regulated by ascending brain stem, basal forebrain (BF) and hypothalamic arousal systems and inhibition or disruption of these systems reduces brain arousal, impairs cognition, and promotes sleep. The internal circadian timekeeping system modulates cognition and affective function by projections from the master circadian clock, located in the hypothalamic suprachiasmatic nuclei (SCN), to arousal and sleep systems and via clock gene oscillations in brain tissues. Understanding the basic principles of circadian and wakefulness-sleep physiology can help to recognize how the circadian system modulates human cognition and influences learning, memory and emotion. Developmental changes in sleep and circadian processes and circadian misalignment in circadian rhythm sleep disorders have important implications for learning, memory and emotion. Overall, when wakefulness occurs at appropriate internal biological times, circadian clockwork benefits human cognitive and emotion function throughout the lifespan. Yet, when wakefulness occurs at inappropriate biological times because of environmental pressures (e.g., early school start times, long work hours that include work at night, shift work, jet lag) or because of circadian rhythm sleep disorders, the resulting misalignment between circadian and wakefulness-sleep physiology leads to impaired cognitive performance, learning, emotion, and safety

Exposure to acetylcholinesterase inhibitors alters the physiology and motor function of honeybees

Cholinergic signalling is fundamental to neuro-muscular function in most organisms. Sub-lethal doses of neurotoxic pesticides that target cholinergic signalling can alter the behaviour of insects in subtle ways; their influence on non-target organisms may not be readily apparent in simple mortality studies. Beneficial arthropods such as honeybees perform sophisticated behavioural sequences during foraging that, if influenced by pesticides, could impair foraging success and reduce colony health. Here, we investigate the behavioural effects on honeybees of exposure to a selection of pesticides that target cholinergic signalling by inhibiting acetylcholinesterase (AChE). To examine how continued exposure to AChE inhibitors affected motor function, we fed adult foraging worker honeybees sub-lethal concentrations of these compounds in sucrose solution for 24 h. Using an assay for locomotion in bees, we scored walking, stopped, grooming, and upside down behaviour continuously for 15 min. At a 10nM concentration, all the AChE inhibitors caused similar effects on behaviour, notably increased grooming activity and changes in the frequency of bouts of behaviour such as head grooming. Coumaphos caused dose-dependent effects on locomotion as well as grooming behaviour, and a 1µM concentration of coumaphos induced symptoms of malaise such as abdomen grooming and defecation. Biochemical assays confirmed that the 4 compounds we assayed (coumaphos, aldicarb, chlorpyrifos, and donepezil) or their metabolites acted as AChE inhibitors in bees. Furthermore, we show that transcript expression levels of two honeybee acetylcholinesterase inhibitors were selectively upregulated in the brain and in gut tissues in response to AChE inhibitor exposure. The results of our study imply that the effects of pesticides that rely on this mode of action have subtle yet profound effects on physiological effects on behaviour that could lead to reduced survival

Trends and correlates of marijuana use among late middle-aged and older adults in the United States, 2002–2014

BACKGROUND: Recent trend studies suggest that marijuana use is on the rise among the general population of adults ages 18 and older in the United States. However, little is known about the trends in marijuana use and marijuana-specific risk/protective factors among American adults during the latter part of adulthood. METHOD: Findings are based on repeated, cross-sectional data collected from late middle-aged (ages 50–64) and older adults (ages 65 and older) surveyed as part of the National Survey on Drug Use and Health between 2002 and 2014. RESULTS: The prevalence of past-year marijuana use among late middle-aged adults increased significantly from a low of 2.95% in 2003 to a high of 9.08% in 2014. Similarly, the prevalence of marijuana use increased significantly among older adults from a low of 0.15% in 2003 to a high of 2.04% in 2014. Notably, the upward trends in marijuana use remained significant even when accounting for sociodemographic, substance use, behavioral, and health-related factors. We also found that decreases in marijuana-specific protective factors were associated with the observed trend changes in marijuana use among late middle-aged and older adults, and observed a weakening of the association between late-middle aged marijuana use and risk propensity, other illicit drug use, and criminal justice system involvement over the course of the study. CONCLUSIONS: Findings from the present study provide robust evidence indicating that marijuana use among older Americans has increased markedly in recent years, with the most evident changes observed between 2008 and 2014

Firearm injury among people experiencing homelessness: Cross-sectional evidence from a national survey of United States emergency departments

OBJECTIVES: Persons experiencing homelessness (PEH) are at high risk for violent victimization. This study leverages unique data from a national study in the United States of America to provide estimates of non-fatal firearm injury among PEH and to describe the contexts related to injury, such as substance use, intent of the injury, and precipitating interpersonal factors. STUDY DESIGN: Cross-sectional. METHODS: Data from the 1993-2020 National Electronic Injury Surveillance System-Firearm Injury Surveillance Study (NEISS-FISS) were used to describe the context and characteristics of non-fatal firearm injury among PEH aged 16 years or older. Homeless status and substance use data were extracted from a de-identified narrative field. Estimates were weighted to account for the NEISS-FISS complex sampling design. RESULTS: Probable homelessness was identified in 0.10% of cases (n = 3,225). Substance use was documented in 22.73% of cases. Assault comprised 82.64% of injuries. Patients were mostly male (81.38%). Missing data were common on contextual variables: verbal argument (64.62%), physical fight (54.48%) or other criminal activity (62.33%). CONCLUSIONS: Assault is a leading cause of non-fatal firearm injury for PEH and is greater than rates of assault in non-fatal firearm injuries in the general population. Substance use was documented in nearly one quarter of patients, although this is less than expected given prior evidence. Reliance on narrative fields for key variables likely underestimates rates of PEH and substance use

Characterizing Sediment from Riverton, WY

Riverton, Wyoming is home to the seventh-largest Native American Reservation by area and a former uranium processing facility. Milling activities at this site have left the sediments and groundwater with elevated concentrations of uranium that occasionally disrupt water quality to the 12,000 residents of the reservation. The floodplain becomes seasonally wet and sometimes flooded from snowmelt that can be amplified by El Niño events. As a result, the sediments of this area experience periodic droughts and floods. There is concern that a decreased water stage can have major impacts on the geochemical makeup of this ecosystem as 1) a decreased water volume may result in an increase of pollutant concentrations and 2) a decreased water stage can have a significant impact the redox cycling within the subsurface and affect major biogeochemical cycles. This study addresses the need to understand current subsurface elemental distributions in Riverton, Wyoming. Overall, the project explores the sediment characteristics of several Riverton cores in response to drought and flood conditions. Samples for this study were taken over the course of twelve months - at three different time points. This summer, 105 Riverton sediment samples from August 2016 (the final time point) were geochemically characterized and compared to samples from dry conditions (August 2015) prior to the second largest flood on record at this location. We expect the sediments collected prior to the flood to vary greatly from the sediments collected after the flood because the activity of microbial communities is affected by differences in the physical structure of the soil. This data, along with an analysis of the microbial communities present in these sediments, will help the Francis Lab understand what factors shape the distribution and diversity of microbial communities present in order to better understand the subsurface biogeochemistry at Riverton