| 1. |
-
- 2017
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:2
-
Tidskriftsartikel (refereegranskat)
|
|
| 2. |
- Rauer, H., et al.
(författare)
-
The PLATO 2.0 mission
- 2014
-
Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 38:1-2, s. 249-330
-
Tidskriftsartikel (refereegranskat)abstract
- PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 s readout cadence and 2 with 2.5 s cadence) providing a wide field-of-view (2232 deg(2)) and a large photometric magnitude range (4-16 mag). It focuses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2 %, 4-10 % and 10 % for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50 % of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0. The PLATO 2.0 catalogue allows us to e. g.: - complete our knowledge of planet diversity for low-mass objects, - correlate the planet mean density-orbital distance distribution with predictions from planet formation theories,- constrain the influence of planet migration and scattering on the architecture of multiple systems, and - specify how planet and system parameters change with host star characteristics, such as type, metallicity and age. The catalogue will allow us to study planets and planetary systems at different evolutionary phases. It will further provide a census for small, low-mass planets. This will serve to identify objects which retained their primordial hydrogen atmosphere and in general the typical characteristics of planets in such a low-mass, low-density range. Planets detected by PLATO 2.0 will orbit bright stars and many of them will be targets for future atmosphere spectroscopy exploring their atmospheres. Furthermore, the mission has the potential to detect exomoons, planetary rings, binary and Trojan planets. The planetary science possible with PLATO 2.0 is complemented by its impact on stellar and galactic science via asteroseismology as well as light curves of all kinds of variable stars, together with observations of stellar clusters of different ages. This will allow us to improve stellar models and study stellar activity. A large number of well-known ages from red giant stars will probe the structure and evolution of our Galaxy. Asteroseismic ages of bright stars for different phases of stellar evolution allow calibrating stellar age-rotation relationships. Together with the results of ESA's Gaia mission, the results of PLATO 2.0 will provide a huge legacy to planetary, stellar and galactic science.
|
|
| 3. |
|
|
| 4. |
- Sumaila, U. Rashid, et al.
(författare)
-
WTO must ban harmful fisheries subsidies
- 2021
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 374:6567, s. 544-544
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 5. |
- Ozgen, H, et al.
(författare)
-
International Consensus Statement for the Screening, Diagnosis, and Treatment of Adolescents with Concurrent Attention-Deficit/Hyperactivity Disorder and Substance Use Disorder
- 2020
-
Ingår i: European addiction research. - : S. Karger AG. - 1421-9891 .- 1022-6877. ; 26:4-5, s. 223-232
-
Tidskriftsartikel (refereegranskat)abstract
- <b><i>Background:</i></b> Childhood attention-deficit/hyperactivity disorder (ADHD) is a risk factor for substance misuse and substance use disorder (SUD) in adolescence and (early) adulthood. ADHD and SUD also frequently co-occur in treatment-seeking adolescents, which complicates diagnosis and treatment and is associated with poor treatment outcomes. Research on the effect of treatment of childhood ADHD on the prevention of adolescent SUD is inconclusive, and studies on the diagnosis and treatment of adolescents with ADHD and SUD are scarce. Thus, the available evidence is generally not sufficient to justify robust treatment recommendations. <b><i>Objective:</i></b> The aim of the study was to obtain a consensus statement based on a combination of scientific data and clinical experience. <b><i>Method:</i></b> A modified Delphi study to reach consensus based upon the combination of scientific data and clinical experience with a multidisciplinary group of 55 experts from 17 countries. The experts were asked to rate a set of statements on the effect of treatment of childhood ADHD on adolescent SUD and on the screening, diagnosis, and treatment of adolescents with comorbid ADHD and SUD. <b><i>Results:</i></b> After 3 iterative rounds of rating and adapting 37 statements, consensus was reached on 36 of these statements representing 6 domains: general (<i>n</i> = 4), risk of developing SUD (<i>n</i> = 3), screening and diagnosis (<i>n</i> = 7), psychosocial treatment (<i>n</i> = 5), pharmacological treatment (<i>n</i> = 11), and complementary treatments (<i>n</i> = 7). Routine screening is recommended for ADHD in adolescent patients in substance abuse treatment and for SUD in adolescent patients with ADHD in mental healthcare settings. Long-acting stimulants are recommended as the first-line treatment of ADHD in adolescents with concurrent ADHD and SUD, and pharmacotherapy should preferably be embedded in psychosocial treatment. The only remaining no-consensus statement concerned the requirement of abstinence before starting pharmacological treatment in adolescents with ADHD and concurrent SUD. In contrast to the majority, some experts required full abstinence before starting any pharmacological treatment, some were against the use of stimulants in the treatment of these patients (independent of abstinence), while some were against the alternative use of bupropion. <b><i>Conclusion:</i></b> This international consensus statement can be used by clinicians and patients together in a shared decision-making process to select the best interventions and to reach optimal outcomes in adolescent patients with concurrent ADHD and SUD.
|
|
| 6. |
- Ozgen, H, et al.
(författare)
-
[International Consensus Statement for the Screening, Diagnosis, and Treatment of Adolescents with Concurrent Attention-Deficit/Hyperactivity Disorder and Substance Use Disorder]
- 2022
-
Ingår i: Zeitschrift fur Kinder- und Jugendpsychiatrie und Psychotherapie. - : Hogrefe Publishing Group. - 1422-4917 .- 1664-2880. ; 50:1, s. 54-67
-
Tidskriftsartikel (refereegranskat)abstract
- Zusammenfassung. Hintergrund: Eine Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung (ADHS) im Kindesalter stellt einen Risikofaktor für Substanzmissbrauch und Störungen durch Substanzgebrauch (Substance Use Disorder, SUD) in der Pubertät und dem (frühen) Erwachsenenalter dar. ADHS und SUD treten auch häufig bei therapiesuchenden Jugendlichen auf, was die Diagnosestellung und Therapie erschwert sowie mit schlechten Behandlungsergebnissen verbunden ist. Forschungsergebnisse über die Wirkung der Behandlung von ADHS im Kindesalter auf die Prävention von SUD im Jugendalter sind nicht eindeutig und Studien über die Diagnose und Behandlung von Jugendlichen mit ADHS und SUD sind selten. Daher reicht die verfügbare Evidenz allgemein nicht aus, um starke Behandlungsempfehlungen zu rechtfertigen. Fragestellung: Ziel dieser Arbeit war es, eine Konsenserklärung auf der Grundlage von wissenschaftlichen Daten und klinischen Erfahrungen zu erhalten. Methodik: Es wurde eine modifizierte Delphi-Studie durchgeführt, um basierend auf der Kombination von wissenschaftlichen Daten und klinischer Erfahrung mit einer multidisziplinären Gruppe von 55 Expert_innen aus 17 Ländern einen Konsens zu erzielen. Die Expert_innen wurden gebeten, eine Reihe von Aussagen über die Wirkung der Behandlung von ADHS im Kindesalter auf die SUD bei Jugendlichen sowie über das Screening, die Diagnostik und die Behandlung von Jugendlichen mit komorbidem ADHS und SUD zu bewerten. Ergebnisse: Nach drei iterativen Bewertungsrunden und der Anpassung von 37 Aussagen wurde ein Konsens über 36 dieser Aussagen erzielt, die sechs Bereiche repräsentieren: allgemein ( n = 4), Risiko der Entwicklung einer SUD ( n = 3), Screening und Diagnostik ( n = 7), psychosoziale Behandlung ( n = 5), pharmakologische Behandlung ( n = 11) und komplementäre Behandlungen ( n = 7). Der Einsatz von Routinescreenings auf ADHS wird bei adoleszenten Patient_innen in einer Suchtbehandlung ebenso wie Routinescreenings auf SUD bei jugendlichen Patient_innen mit ADHS in allgemeinpsychiatrischen Therapiesettings empfohlen. Langwirksame Stimulanzien werden als Behandlung der ersten Wahl von ADHS bei Jugendlichen mit gleichzeitiger ADHS und SUD empfohlen. Die Pharmakotherapie sollte vorzugsweise in psychosoziale Behandlung eingebettet werden. Die einzige nichtkonsentierte Aussage betraf die Notwendigkeit von Abstinenz vor Beginn einer pharmakologischen Behandlung bei Jugendlichen mit ADHS und gleichzeitigem SUD. Im Gegensatz zur Mehrheit verlangten einige Expert_innen eine vollständige Abstinenz vor Beginn einer pharmakologischen Behandlung, einige waren gegen die Verwendung von Stimulanzien bei der Behandlung dieser Patient_innen (unabhängig von Abstinenz), während einige sich gegen die alternative Anwendung von Bupropion aussprachen. Schlussfolgerungen: Diese internationale Konsenserklärung kann von Kliniker_innen und Patient_innen zusammen in einem gemeinsamen Entscheidungsprozess genutzt werden, um die besten Interventionen auszuwählen und die bestmöglichen Ergebnisse bei adoleszenten Patient_innen mit gleichzeitiger ADHS und SUD zu erzielen.
|
|
| 7. |
- Quanz, S. P., et al.
(författare)
-
Large Interferometer For Exoplanets (LIFE) I. Improved exoplanet detection yield estimates for a large mid-infrared space-interferometer mission
- 2022
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 664
-
Tidskriftsartikel (refereegranskat)abstract
- Context. One of the long-term goals of exoplanet science is the atmospheric characterization of dozens of small exoplanets in order to understand their diversity and search for habitable worlds and potential biosignatures. Achieving this goal requires a space mission of sufficient scale that can spatially separate the signals from exoplanets and their host stars and thus directly scrutinize the exoplanets and their atmospheres.Aims. We seek to quantify the exoplanet detection performance of a space-based mid-infrared (MIR) nulling interferometer that measures the thermal emission of exoplanets. We study the impact of various parameters and compare the performance with that of large single-aperture mission concepts that detect exoplanets in reflected light.Methods. We have developed an instrument simulator that considers all major astrophysical noise sources and coupled it with Monte Carlo simulations of a synthetic exoplanet population around main-sequence stars within 20 pc of the Sun. This allows us to quantify the number (and types) of exoplanets that our mission concept could detect. Considering single visits only, we discuss two different scenarios for distributing 2.5 yr of an initial search phase among the stellar targets. Different apertures sizes and wavelength ranges are investigated.Results. An interferometer consisting of four 2 m apertures working in the 4–18.5 μ.m wavelength range with a total instrument throughput of 5% could detect up to ≈550 exoplanets with radii between 0.5 and 6 R⊕ with an integrated S/N ≥ 7. At least ≈160 of the detected exoplanets have radii ≤1.5 R⊕. Depending on the observing scenario, ≈25–45 rocky exoplanets (objects with radii between 0.5 and 1.5 R⊕) orbiting within the empirical habitable zone (eHZ) of their host stars are among the detections. With four 3.5 m apertures, the total number of detections can increase to up to ≈770, including ≈60–80 rocky eHZ planets. With four times 1 m apertures, the maximum detection yield is ≈315 exoplanets, including ≤20 rocky eHZ planets. The vast majority of small, temperate exoplanets are detected around M dwarfs. The impact of changing the wavelength range to 3–20 μm or 6–17 μm on the detection yield is negligible.Conclusions. A large space-based MIR nulling interferometer will be able to directly detect hundreds of small, nearby exoplanets, tens of which would be habitable world candidates. This shows that such a mission can compete with large single-aperture reflected light missions. Further increasing the number of habitable world candidates, in particular around solar-type stars, appears possible via the implementation of a multi-visit strategy during the search phase. The high median S/N of most of the detected planets will allow for first estimates of their radii and effective temperatures and will help prioritize the targets for a second mission phase to obtain high-S/N thermal emission spectra, leveraging the superior diagnostic power of the MIR regime compared to shorter wavelengths.
|
|
| 8. |
- Gonzalez, RA, et al.
(författare)
-
Onset and Severity of Early Disruptive Behavioral Disorders in Treatment-Seeking Substance Use Disorder Patients with and without Attention-Deficit/Hyperactivity Disorder
- 2020
-
Ingår i: European addiction research. - : S. Karger AG. - 1421-9891 .- 1022-6877. ; 26:4-5, s. 211-222
-
Tidskriftsartikel (refereegranskat)abstract
- <b><i>Aims:</i></b> This study addressed the age of onset of conduct disorder (CD) and oppositional defiant disorder (ODD) in treatment-seeking substance use disorder (SUD) patients with and without adult attention-deficit/hyperactivity disorder (ADHD) and its association with early onset of SUD. <b><i>Methods:</i></b> We examined data from the 2nd <i>International ADHD in Substance Use Disorders Prevalence Study</i>, including 400 adults in SUD treatment from Puerto Rico, Hungary, and Australia. ADHD, SUD, and CD/ODD were assessed with the <i>Conners Adult ADHD Diagnostic Interview for DSM-IV</i>, the <i>MINI International Neuropsychiatric Interview</i>, and the K-SADS, respectively. Cox regression analyses modeled time to emergence of CD/ODD separately for SUD patients with and without adult ADHD. Linear regression models examined associations between age of onset of SUD and presence of ADHD and adjusted for sex, age, and country. To assess the mediating role of CD/ODD on the association of ADHD with onset of SUD, adjusted regression models were estimated. <b><i>Results:</i></b> Treatment-seeking SUD patients with ADHD presented an earlier onset of CD/ODD compared with those without ADHD. CD/ODD symptom loads were higher among the SUD and ADHD group. Age of first substance use and SUD were significantly earlier in SUD patients with ADHD, and these findings remained significant after adjustment for demographics and coexisting CD/ODD. <b><i>Conclusions:</i></b> ADHD is associated with earlier onset of SUD as well as with an earlier onset of more frequent and more severe disruptive behavioral disorders. These findings may inform preventive interventions to mitigate adverse consequences of ADHD.
|
|
| 9. |
- Douketis, J D, et al.
(författare)
-
Perioperative bridging anticoagulation during dabigatran or warfarin interruption among patients who had an elective surgery or procedure : Substudy of the RE-LY trial
- 2015
-
Ingår i: Thrombosis and Haemostasis. - : Georg Thieme Verlag KG. - 0340-6245 .- 2567-689X. ; 113:3, s. 625-632
-
Tidskriftsartikel (refereegranskat)abstract
- In patients with atrial fibrillation (AF) who require interruption of dabigatran or warfarin for an elective surgery/procedure, the risks and benefits of perioperative bridging anticoagulation is uncertain. We accessed the database from RE-LY, a randomised trial comparing dabigatran with warfarin for stroke prevention in AF, to assess the potential benefits and risks of bridging. In patients who had a first interruption of dabigatran or warfarin for an elective surgery/procedure, we compared the risk for major bleeding (MB), stroke or systemic embolism (SSE) and any thromboembolism (TE) in patients who were bridged or not bridged during the period of seven days before until 30 days after surgery/procedure. We used multivariable Cox regression to adjust for potential confounders. Bridging was used more during warfarin interruption than dabigatran interruption (27.5 % vs 15.4 %; p< 0.001). With dabigatran interruption, bridged patients had more MB (6.5 % vs. 1.8 %, P< 0.001) than those not bridged but bridged and not bridged groups did not differ for any TE (1.2 % vs 0.6 %, p=0.16) and SSE (0.5 % vs 0.3 %, p=0.46). With warfarin interruption, bridged patients had more MB (6.8 % vs 1.6 %, p< 0.001) and any TE (1.8 % vs 0.3 %, p=0.007) than those not bridged but bridged and not bridged groups did not differ for SSE (0.5 % vs 0.2 %, p=0.321). In conclusion, in patients who interrupted dabigatran or warfarin for a surgery/procedure in the RE-LY trial, use of bridging anticoagulation appeared to increase the risk for major bleeding irrespective of dabigatran or warfarin interruption.
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
- Borowski, Thomasz, et al.
(författare)
-
Mechanism of Selective Halogenation by SyrB2 : A Computational Study
- 2010
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 132:37, s. 12887-12898
-
Tidskriftsartikel (refereegranskat)abstract
- The mechanism of the chlorination reaction of SyrB2, a representative α-ketoglutarate dependent halogenase, was studied with computational methods. First, a macromolecular model of the Michaelis com- plex was constructed using molecular docking proce- dures. Based on this structure a smaller model com- prising the first- and some of the second shell residues of iron, and a model substrate was constructed and used in DFT investigations on the reaction mecha- nism. Computed relative energies and Mo ̈ssbauer iso- mer shifts and quadrupole splittings indicate that the two oxoferryl species observed experimentally are two stereoisomers resulting from an exchange of the coordi- nation sites occupied by the oxo and chloro ligands. In principle both FeIV =O species are reactive and decay to FeIIICl(OH)/carbon radical intermediates via C-H bond cleavage. In the final rebound step, which is very fast and thus precluding equilibration between the two forms of the radical intermediate, the ligand (oxo or chloro) placed closest to the carbon radical (trans to His235) is transfered to the carbon. For the native substrate (L-Thr) the lowest barrier for C-H cleavage was found for an isomer of the oxoferryl species favor- ing chlorination in the rebound step. CASPT2 cal- culations for the spin state splittings in the oxoferryl species support the conclusion that once the FeIV =O intermediate is formed, the reaction proceeds on the quintet potential energy surface.
|
|
| 15. |
- Cockell, C.S., et al.
(författare)
-
Habitability : a review
- 2016
-
Ingår i: Astrobiology. - : Mary Ann Liebert Inc. - 1531-1074 .- 1557-8070. ; 16:1, s. 89-117
-
Tidskriftsartikel (refereegranskat)abstract
- Habitability is a widely used word in the geoscience, planetary science, and astrobiology literature, but what does it mean? In this review on habitability, we define it as the ability of an environment to support the activity of at least one known organism. We adopt a binary definition of “habitability” and a “habitable environment.” An environment either can or cannot sustain a given organism. However, environments such as entire planets might be capable of supporting more or less species diversity or biomass compared with that of Earth. A clarity in understanding habitability can be obtained by defining instantaneous habitability as the conditions at any given time in a given environment required to sustain the activity of at least one known organism, and continuous planetary habitability as the capacity of a planetary body to sustain habitable conditions on some areas of its surface or within its interior over geological timescales. We also distinguish between surface liquid water worlds (such as Earth) that can sustain liquid water on their surfaces and interior liquid water worlds, such as icy moons and terrestrial-type rocky planets with liquid water only in their interiors. This distinction is important since, while the former can potentially sustain habitable conditions for oxygenic photosynthesis that leads to the rise of atmospheric oxygen and potentially complex multicellularity and intelligence over geological timescales, the latter are unlikely to. Habitable environments do not need to contain life. Although the decoupling of habitability and the presence of life may be rare on Earth, it may be important for understanding the habitability of other planetary bodies
|
|
| 16. |
- Ericson, Dan, et al.
(författare)
-
Minimally invasive dentistry : concepts and techniques in cariology
- 2003
-
Ingår i: Oral Health & Preventive Dentistry. - 1602-1622 .- 1757-9996. ; 1:1, s. 59-72
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The concept ‘Minimally Invasive Dentistry’ can be defined as maximal preservation of healthy dental structures. Within cariology, this concept includes the use of all available information and techniques ranging from accurate diagnosis of caries, caries risk assessment and prevention, to technical procedures in repairing restorations. Dentists are currently spending more than half their time replacing old restorations. The main reasons for restoration failures are secondary caries and fractures, factors that are generally not addressed in the technical process of replacing a restoration. Prevailing concepts on minimally invasive dentistry seem to be ‘product or technique-motivated’, challenging one technique or product with another, rather than focusing on a general concept. New knowledge of caries progression rates has also led to substantial modification of restorative intervention thresholds and further handling of the disease. New diagnostic tools for caries lesion detection, caries risk assessment and focused preventive treatments have decreased the need for early restorative interventions. In parallel to this, new techniques for cutting teeth and removing decay have evolved. This paper focuses on describing minimally invasive dentistry in cariology from a conceptual perspective, relating to clinical caries diagnosis, restorative intervention thresholds and operative procedures, with special reference to survival of tunnel and slot restorations and to repair vs. replacement of defective restorations.
|
|
| 17. |
- Georgiev, Valentin, et al.
(författare)
-
A DFT Study on the Catalytic Reactivity of a Functional Model Complex for Intradiol-Cleaving Dioxygenases
- 2010
-
Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 114:17, s. 5878-5885
-
Tidskriftsartikel (refereegranskat)abstract
- The enzymatic ring cleavage of catechol derivatives is catalyzed by two groups of dioxygenases: extradiol- and intradiol-cleaving dioxygenases. Although having different oxidation state of their nonheme iron sites and different ligand coordinations, both groups of enzymes involve a common peroxy intermediate in their catalytic cycles. The factors that lead to either extradiol cleavage resulting in 2-hydroxymuconaldehyde or intradiol cleavage resulting in muconic acid are not fully understood. Well-characterized model compounds that mimic the functionality of these enzymes offer a basis for direct comparison to theoretical results. In this study the mechanism of a biomimetic iron complex is investigated with density functional theory (DFT). This complex catalyzes the ring opening of catecholate with exclusive formation of the intradiol cleaved product. Several spin states are possible for the transition metal system, with the quartet state found to be of main importance during the reaction course. The mechanism investigated provides an explanation for the observed selectivity of the complex. First, a bridging peroxide is formed, which decomposes to an alkoxy radical by O−O homolysis. In contrast to the subsequent barrier-free intradiol C−C bond cleavage, the extradiol pathway proceeds via the formation of an epoxide, which requires an additional activation barrier.
|
|
| 18. |
- Hedlund, Jonas, et al.
(författare)
-
ZSM-5 membranes synthesized without organic templates using a seeding technique
- 1999
-
Ingår i: Journal of Membrane Science. - 0376-7388 .- 1873-3123. ; 159:1-2, s. 263-273
-
Tidskriftsartikel (refereegranskat)abstract
- Porous α-alumina supports were seeded with colloidal TPA-silicalite-1 crystals and calcined. The supports were treated in a synthesis solution to grow the seed crystals into ZSM-5 films. The synthesis solution was free from organic template molecules in order to avoid the calcination step which often introduces cracks in the synthesized zeolite film. An SEM investigation indicated that the zeolite films on the supports were defect free and that the film thickness was approximately 1.5 μm. XRD data showed that the film consisted of well-crystallized ZSM-5. The permeance in single gas experiments decreased in the order H2O, H2, CO2, O2, N2 and CH4. The difference in permeance between each molecular species in the series was almost one order of magnitude which indicated that the membranes were of a high quality. Molecules larger than CH4 permeated with similar and low rates, independent of their kinetic diameters, indicating a non-selective permeation path through defects in the zeolite films. However, the permeance of these larger molecules was less than 1/10 000 of that for H2O. The highest measured separation factors for binary mixtures of N2/SF6 and H2/i-C4 were 110 and 99.
|
|
| 19. |
|
|
| 20. |
- Johannes, A., et al.
(författare)
-
Enhanced sputtering and incorporation of Mn in implanted GaAs and ZnO nanowires
- 2014
-
Ingår i: Journal of Physics D: Applied Physics. - Bristol : IOP Publishing. - 1361-6463 .- 0022-3727. ; 47:39
-
Tidskriftsartikel (refereegranskat)abstract
- We simulated and experimentally investigated the sputter yield of ZnO and GaAs nanowires, which were implanted with energetic Mn ions at room temperature. The resulting thinning of the nanowires and the dopant concentration with increasing Mn ion fluency were measured by accurate scanning electron microscopy (SEM) and nano-x-Ray Fluorescence (nanoXRF) quantification, respectively. We observed a clearly enhanced sputter yield for the irradiated nanowires compared to bulk, which is also corroborated by iradina simulations. These show a maximum if the ion range matches the nanowire diameter. As a consequence of the erosion thinning of the nanowire, the incorporation of the Mn dopants is also enhanced and increases non-linearly with increasing ion fluency.
|
|
| 21. |
|
|
| 22. |
- Johansson, Adam Johannes, 1976-, et al.
(författare)
-
Observed enhancement of the reactivity of a biomimetic diiron complex by the addition of water - mechanistic insights from theoretical modeling
- 2009
-
Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 34, s. 6741-6750
-
Tidskriftsartikel (refereegranskat)abstract
- The biomimetic diiron complex [FeIIIFeIV(m-O)2(5-Me3-TPA)2](ClO4)3 (TPA = tris(2- pyridylmethyl)amine) has been found to be capable of oxidizing 9,10-dihydroanthracene in a solution of acetonitrile. Addition of water up to 1 M makes the reaction 200 times faster, suggesting that the water molecule in some way activates the catalyst for more efficient substrate oxidation. It is proposed that the enhanced reactivity results from the coordination of a water molecule to the iron(III) half of the complex, converting the bis-m-oxo structure of the diiron complex to a ring-opened form where one of the bridging oxo groups is transformed into a terminal oxo group on iron(IV). The suggested mechanism is supported by DFT (B3LYP) calculations and transition state theory. Two different computational models of the diiron complex are used to model the hydroxylation of cyclohexane to cyclohexanol. Model 1 has a bis-m-oxo diiron core (diamond core) while model 2 represents the “open core” analogue with one bridging m-oxo group, a terminal oxo ligand on iron(IV), and a water molecule coordinated to iron(III). The computational results clearly suggest that the terminal oxo group is more reactive than the bridging oxo group. The free energy of activation is 7.0 kcal mol-1 lower for the rate limiting step when the oxidant has a terminal oxo group than when both oxo groups are bridging the irons.
|
|
| 23. |
|
|
| 24. |
|
|
| 25. |
|
|
