Localized probing of gas molecule adsorption energies and desorption attempt frequencies

© 2015 American Chemical Society. Gas-mediated electron beam induced etching (EBIE) and deposition (EBID) can be used to measure activation energies that are interpreted as the adsorption energies of surface-adsorbed precursor molecules. However, the measured quantities often disagree with adsorption energies measured by conventional analysis techniques such as thermally programmed desorption and have anomalous dependencies on parameters such as the electron beam current used to perform EBID. Here, we use the theory of EBIE and EBID rate kinetics to explain this behavior and identify conditions under which the activation energies and the associated pre-exponential factors correspond to gas molecule adsorption energies and desorption attempt frequencies, respectively. Under these conditions, EBIE and EBID can be used as robust, nanoscale techniques for the analysis of adsorbates

Robust Solid-State Quantum System Operating at 800 K

© 2017 American Chemical Society. Realization of quantum information and communications technologies requires robust, stable solid-state single-photon sources. However, most existing sources cease to function above cryogenic or room temperature due to thermal ionization or strong phonon coupling, which impedes their emissive and quantum properties. Here we present an efficient single-photon source based on a defect in a van der Waals crystal that is optically stable and operates at elevated temperatures of up to 800 K. The quantum nature of the source and the photon purity are maintained upon heating to 800 K and cooling back to room temperature. Our report of a robust high-temperature solid-state single photon source constitutes a significant step toward practical, integrated quantum technologies for real-world environments

First-principles investigation of quantum emission from hBN defects

© 2017 The Royal Society of Chemistry. Hexagonal boron nitride (hBN) has recently emerged as a fascinating platform for room-temperature quantum photonics due to the discovery of robust visible light single-photon emitters. In order to utilize these emitters, it is necessary to have a clear understanding of their atomic structure and the associated excitation processes that give rise to this single photon emission. Here, we performed density-functional theory (DFT) and constrained DFT calculations for a range of hBN point defects in order to identify potential emission candidates. By applying a number of criteria on the electronic structure of the ground state and the atomic structure of the excited states of the considered defects, and then calculating the Huang-Rhys (HR) factor, we found that the CBVN defect, in which a carbon atom substitutes a boron atom and the opposite nitrogen atom is removed, is a potential emission source with a HR factor of 1.66, in good agreement with the experimental HR factor. We calculated the photoluminescence (PL) line shape for this defect and found that it reproduces a number of key features in the experimental PL lineshape

Robust multicolor single photon emission from point defects in hexagonal boron nitride

© 2017 IEEE. We demonstrates engineering of quantum emitters in hBN multi-layers using either electron beam irradiation or annealing. The defects exhibit a broad range of multicolor room-temperature single photon emissions across the visible and the near-infrared ranges

Climacteric Lowers Plasma Levels of Platelet-Derived Microparticles: A Pilot Study in Pre-versus Postmenopausal Women

Background: Climacteric increases the risk of thrombotic events by alteration of plasmatic coagulation. Up to now, less is known about changes in platelet-(PMP) and endothelial cell-derived microparticles (EMP). Methods: In this prospective study, plasma levels of microparticles (MP) were compared in 21 premenopausal and 19 postmenopausal women. Results: No altered numbers of total MP or EMP were measured within the study groups. However, the plasma values of CD61-exposing MP from platelets/megakaryocytes were higher in premenopausal women (5,364 x 10(6)/l, range 4,384-17,167) as compared to postmenopausal women (3,808 x 10(6)/l, range 2,009-8,850; p = 0.020). This differentiation was also significant for the subgroup of premenopausal women without hormonal contraceptives (5,364 x 10(6)/l, range 4,223-15,916; p = 0.047; n = 15). Furthermore, in premenopausal women, higher plasma levels of PMP exposing CD62P were also present as compared to postmenopausal women (288 x 10(6)/l, range 139-462, vs. 121 x 10(6)/l, range 74-284; p = 0.024). This difference was also true for CD63+ PMP levels (281 x 10(6)/l, range 182-551, vs. 137 x 10(6)/l, range 64-432; p = 0.015). Conclusion: Climacteric lowers the level of PMP but has no impact on the number of EMP in women. These data suggest that PMP and EMP do not play a significant role in enhancing the risk of thrombotic events in healthy, postmenopausal women. Copyright (C) 2012 S. Karger AG, Base

Tetraspanin (TSP-17) Protects Dopaminergic Neurons against 6-OHDA-Induced Neurodegeneration in <i>C. elegans</i>

Parkinson's disease (PD), the second most prevalent neurodegenerative disease after Alzheimer's disease, is linked to the gradual loss of dopaminergic neurons in the substantia nigra. Disease loci causing hereditary forms of PD are known, but most cases are attributable to a combination of genetic and environmental risk factors. Increased incidence of PD is associated with rural living and pesticide exposure, and dopaminergic neurodegeneration can be triggered by neurotoxins such as 6-hydroxydopamine (6-OHDA). In C. elegans, this drug is taken up by the presynaptic dopamine reuptake transporter (DAT-1) and causes selective death of the eight dopaminergic neurons of the adult hermaphrodite. Using a forward genetic approach to find genes that protect against 6-OHDA-mediated neurodegeneration, we identified tsp-17, which encodes a member of the tetraspanin family of membrane proteins. We show that TSP-17 is expressed in dopaminergic neurons and provide genetic, pharmacological and biochemical evidence that it inhibits DAT-1, thus leading to increased 6-OHDA uptake in tsp-17 loss-of-function mutants. TSP-17 also protects against toxicity conferred by excessive intracellular dopamine. We provide genetic and biochemical evidence that TSP-17 acts partly via the DOP-2 dopamine receptor to negatively regulate DAT-1. tsp-17 mutants also have subtle behavioral phenotypes, some of which are conferred by aberrant dopamine signaling. Incubating mutant worms in liquid medium leads to swimming-induced paralysis. In the L1 larval stage, this phenotype is linked to lethality and cannot be rescued by a dop-3 null mutant. In contrast, mild paralysis occurring in the L4 larval stage is suppressed by dop-3, suggesting defects in dopaminergic signaling. In summary, we show that TSP-17 protects against neurodegeneration and has a role in modulating behaviors linked to dopamine signaling

Association of Types of Dietary Fats and All-Cause and Cause-Specific Mortality: A Prospective Cohort Study and Meta-Analysis of Prospective Studies with 1,148,117 Participants

Background: Associations between dietary fats and mortality are unclear. Methods: We evaluated the relationship between quartiles of total fat, mono-unsaturated (MUFA), polyunsaturated (PUFA) and saturated fatty acid (SFA) consumption, and all-cause, coronary heart disease (CHD), stroke, and type 2 diabetes (T2D)-associated mortality in 24,144 participants from the National Health and Nutrition Examination Surveys (NHANES) 1999-2010. We added our results to a meta-analysis based on searches until November 2018. Results: In fully adjusted Cox-proportional hazard models in our prospective study, there was an inverse association between total fat (HR: 0.90, 95% confidence interval 0.82, 0.99, Q4 vs Q1) and PUFA (0.81, 0.78-0.84) consumption and all-cause mortality, whereas SFA were associated with the increased mortality (1.08, 1.04-1.11). In the meta-analysis of 29 prospective cohorts (n=1,148,117) we found a significant inverse association between total fat (0.89, 0.82-0.97), MUFA (0.93, 0.87-0.99) and PUFA (0.86, 0.80-0.93) consumption and all-cause mortality. No association was observed between total fat and CVD (0.92, 0.79-1.08) or CHD mortality (1.03 0.99-1.09). A significant association between SFA intake and CHD mortality (1.10, 1.01-1.20) was observed. Neither MUFA nor PUFA were associated with CVD or CHD mortality. Inverse associations were observed between MUFA (0.80, 0.67-0.96) and PUFA (0.84, 0.80-0.90) intakes and stroke mortality. Conclusions: We showed differential associations of total fat, MUFA and PUFA with all-cause mortality, but not CVD or CHD mortalities. SFA was associated with higher all-cause mortality in NHANES and with CHD mortality in our meta-analysis. The type of fat intake appears to be associated with important health outcomes

A Call for Action: The Application of the International Health Regulations to the Global Threat of Antimicrobial Resistance

Stephen Harbarth and colleagues argue that the International Health Regulations (IHR) should be applied to the global health threat of antimicrobial resistance

Atherosclerosis profile and incidence of cardiovascular events: a population-based survey

<p>Abstract</p> <p>Background</p> <p>Atherosclerosis is a chronic progressive disease often presenting as clinical cardiovascular disease (CVD) events. This study evaluated the characteristics of individuals with a diagnosis of atherosclerosis and estimated the incidence of CVD events to assist in the early identification of high-risk individuals.</p> <p>Methods</p> <p>Respondents to the US SHIELD baseline survey were followed for 2 years to observe incident self-reported CVD. Respondents had subclinical atherosclerosis if they reported a diagnosis of narrow or blocked arteries/carotid artery disease without a past clinical CVD event (heart attack, stroke or revascularization). Characteristics of those with atherosclerosis and incident CVD were compared with those who did not report atherosclerosis at baseline but had CVD in the following 2 years using chi-square tests. Logistic regression model identified characteristics associated with atherosclerosis and incident events.</p> <p>Results</p> <p>Of 17,640 respondents, 488 (2.8%) reported having subclinical atherosclerosis at baseline. Subclinical atherosclerosis was associated with age, male gender, dyslipidemia, circulation problems, hypertension, past smoker, and a cholesterol test in past year (OR = 2.2) [all p < 0.05]. Incident CVD was twice as high in respondents with subclinical atherosclerosis (25.8%) as in those without atherosclerosis or clinical CVD (12.2%). In individuals with subclinical atherosclerosis, men (RR = 1.77, p = 0.050) and individuals with circulation problems (RR = 2.36, p = 0.003) were at greatest risk of experiencing CVD events in the next 2 years.</p> <p>Conclusion</p> <p>Self-report of subclinical atherosclerosis identified an extremely high-risk group with a >25% risk of a CVD event in the next 2 years. These characteristics may be useful for identifying individuals for more aggressive diagnostic and therapeutic efforts.</p

Increased susceptibility to cardiovascular effects of dihydrocapcaicin in resuscitated rats. Cardiovascular effects of dihydrocapsaicin

<p>Abstract</p> <p>Background</p> <p>Survivors of a cardiac arrest often have persistent cardiovascular derangements following cardiopulmonary resuscitation including decreased cardiac output, arrhythmias and morphological myocardial damage. These cardiovascular derangements may lead to an increased susceptibility towards the external and internal environment of the cardiovascular system as compared to the healthy situation.</p> <p>Methods</p> <p>Here we tested the hypothesis that the cardiovascular system in healthy rats and rats resuscitated from a cardiac arrest may be differentially affected by a transient receptor potential vanilloid type 1 agonist, by continuous intravenous infusion of dihydrocapsaicin (DHC).</p> <p>Results</p> <p>Compared to baseline, infusion of DHC caused an initial increase in mean arterial blood pressure in both healthy and resuscitated rats of 25% and 10%, respectively. Also, we observed an initial response of tachycardia in both healthy and resuscitated rats of 30% and 20%, respectively. Then, at high levels of DHC infusion (> 2.0 mg/kg/hr) we observed two single episodes of transient bradycardia and hypotension in 33% of the healthy rats, which was consistent with a TRPV1 agonist induced Bezold-Jarisch reflex. In contrast, in resuscitated rats we observed multiple episodes of bradycardia/hypotension in 100% of the rats and at a dose of DHC of 0.65 mg/kg/hr. Notably, this DHC effect could be completely blocked in the resuscitated rats by pre-treatment with atropine, a muscarinic acetylcholine antagonist.</p> <p>Conclusions</p> <p>Our results indicate that the susceptibility of the rats towards TRPV1 agonist induced Bezold-Jarisch reflex is increased in those resuscitated from cardiac arrest compared to the healthy situation.</p