Phosphorene nanoribbons (PNRs) can be synthesised in intrinsically scalable methods from intercalation of black phosphorus (BP), however, the mechanism of ribbonisation remains unclear. Herein, to ...investigate the point at which nanoribbons form, we decouple the two key synthesis steps: first, the formation of the BP intercalation compound, and second, the dissolution into a polar aprotic solvent. We find that both the lithium intercalant and the negative charge on the phosphorus host framework can be effectively removed by addition of phenyl cyanide to return BP and investigate whether fracturing to ribbons occurred after the first step. Further efforts to exfoliate mechanically with or without solvent reveal that the intercalation step does not form ribbons, indicating that an interaction between the amidic solvent and the intercalated phosphorus compound plays an important role in the formation of nanoribbons.
Phosphorene nanoribbons can be synthesised in by intercalation of black phosphorus with Li followed by dissolution in amides. Our result suggest that the first step does not cut the sheets to ribbons, indicating they are cut by solvent interactions.
We describe an approach to generating and verifying well-defined redox states in metalloprotein single crystals by combining electrochemical control with synchrotron infrared microspectroscopic ...imaging. For NiFe hydrogenase 1 from Escherichia coli we demonstrate fully reversible and uniform electrochemical reduction from the oxidised inactive to the fully reduced state, and temporally resolve steps during this reduction.
ABSTRACT
Following frequency and mode identification of two candidate γ Doradus stars, HD 103257 and HD 109799, both can be categorized as bona-fide members of the class. Over 250 high-resolution ...spectra of the two stars were collected at University of Canterbury Mount John Observatory (UCMJO) using the High Efficiency and Resolution Canterbury University Large Echelle Spectrograph (HERCULES) spectrograph. The spectra were cross-correlated with a synthetic δ-function template to produce line-profiles and further augmented with high-quality photometry from the Transiting Exoplanet Survey Satellite (TESS) mission, the Wide Angle Search for Planets (WASP) archive, and HIPPARCOS catalogue for frequency and mode analysis. Frequency analysis was carried out using FAMIAS and SigSpec. Two pulsation frequencies were identified in the spectra for HD 103257: 1.22496 ± 0.00001 and 1.14569 ± 0.00002 d−1, explaining 58.9 ${{\ \rm per\ cent}}$ of the variation across the line profiles. Both frequencies were characterized with best-fitting modes of (ℓ, m) = (1, 1). Two pulsation frequencies were identified in the spectra for HD 109799: 1.48679 ± 0.00002 and 1.25213 ± 0.00002 d−1, explaining 32.6 ${{\ \rm per\ cent}}$ of the variation across the line profiles. Both frequencies also yielded individual mode fits of modes (ℓ, m) = (1, 1). The excellent quality photometry from TESS observations has proven complementary to the work herein, and will provide a meaningful opportunity for deeper analysis of additional stars in the HERCULES catalogue. This will be a key component in the continued development of models relating to the processes within γ Doradus stars.
Numerous layered materials are being recognized as promising candidates for high-performance alkali-ion battery anodes, but black phosphorus (BP) has received particular attention. This is due to its ...high specific capacity, due to a mixed alkali-ion storage mechanism (intercalation-alloying), and fast alkali-ion transport within its layers. Unfortunately, BP based batteries are also commonly associated with serious irreversible losses and poor cycling stability. This is known to be linked to alloying, but there is little experimental evidence of the morphological, mechanical, or chemical changes that BP undergoes in operational cells and thus little understanding of the factors that must be mitigated to optimize performance. Here the degradation mechanisms of BP alkali-ion battery anodes are revealed through operando electrochemical atomic force microscopy (EC-AFM) and ex situ spectroscopy. Among other phenomena, BP is observed to wrinkle and deform during intercalation but suffers from complete structural breakdown upon alloying. The solid electrolyte interphase (SEI) is also found to be unstable, nucleating at defects before spreading across the basal planes but then disintegrating upon desodiation, even above alloying potentials. By directly linking these localized phenomena with the whole-cell performance, we can now engineer stabilizing protocols for next-generation high-capacity alkali-ion batteries.
Black phosphorene quantum dots (BPQDs) are most commonly derived from high‐cost black phosphorus, while previous syntheses from the low‐cost red phosphorus (Pred) allotrope are highly oxidised. ...Herein, we present an intrinsically scalable method to produce high quality BPQDs, by first ball‐milling Pred to create nanocrystalline Pblack and subsequent reductive etching using lithium electride solvated in liquid ammonia. The resultant ~25 nm BPQDs are crystalline with low oxygen content, and spontaneously soluble as individualized monolayers in tertiary amide solvents, as directly imaged by liquid‐phase transmission electron microscopy. This new method presents a scalable route to producing quantities of high quality BPQDs for academic and industrial applications.
Black phosphorene quantum dots can now be made at remarkably low cost in a simple two step process. Ball milling cheap abundant red phosphorus creates quantu dots trapped in bulk, which can then be freed by etching the surrounding amorphous phosphorus with lithium electride solution.
Objectives
This study aimed to evaluate the association between outdoor ambient air pollution and emergency department (ED) visits for epistaxis.
Design
Cross‐sectional study, case–crossover design.
...Setting
ED visit data were obtained for Edmonton, Alberta, Canada, for a period of 10 years starting 1 April 1992 and ending March 31st of 2002. The data on ED visits were supplied by Capital Health for the five major acute care hospitals in the Edmonton area.
Participants
The analysis was performed for the population as a whole (N = 15 038) and split by sex: males (N = 8587) and females (N = 6451).
Main outcome measures
We explored associations between ambient concentrations of air pollutants (CO, NO2, SO2, O3, PM10, PM2.5) lagged by 0–4 days and ED visits for epistaxis in Edmonton, Alberta, Canada.
Results
Odds ratios (ORs) and their 95% confidence intervals (CI) were reported for an increase in an interquartile range (IQR) of pollutant concentration. We obtained positive and statistically significant results for all patients with epistaxis; exposure to O3 with IQR = 14 ppb, OR = 1.05 (95% CI: 1.00–1.09, lag 0), and for males (age < 25 years), OR = 1.16 (1.03–1.30), lag 4; and to PM10 with IQR = 15 μg/m3, OR = 1.02 (1.00–1.05, lag 3). These results were stronger for older (age > 24 years) females.
Conclusions
These findings suggest that there may be an association between air pollutant exposure, specifically ozone and PM10, and the number of ED visits for epistaxis.
Quasi-1D nanoribbons provide a unique route to diversifying the properties of their parent 2D nanomaterial, introducing lateral quantum confinement and an abundance of edge sites. Here, a new family ...of nanomaterials is opened with the creation of arsenic–phosphorus alloy nanoribbons (AsPNRs). By ionically etching the layered crystal black arsenic–phosphorus using lithium electride followed by dissolution in amidic solvents, solutions of AsPNRs are formed. The ribbons are typically few-layered, several micrometers long with widths tens of nanometers across, and both highly flexible and crystalline. The AsPNRs are highly electrically conducting above 130 K due to their small band gap (ca. 0.035 eV), paramagnetic in nature, and have high hole mobilities, as measured with the first generation of AsP devices, directly highlighting their properties and utility in electronic devices such as near-infrared detectors, quantum computing, and charge carrier layers in solar cells.
Regardless of the effectiveness of nonhuman animal programs to reduce recidivism among offenders, such programs are popular and used widely in the United States correctional system. Proponents cite ...measured improvements in attitudes and behaviors among prisoners, and report benefits from building trust with local and national organizations. The present study compared responses from inmates and staff associated with dog training programs in Pennsylvania's Department of Corrections. Generally, all participants viewed the dog training program positively, agreeing that it reduced recidivism and inmate misconduct, and increased morale and positive social interactions. Inmates perceived the programs to be more effective than staff for reducing recidivism and for improving marketable skills. Female participants and participants from female institutions agreed more that the programs decreased recidivism and non-violent incidents in prison, and brought all inmates together as a community, compared to male participants and those from male institutions, respectively. Policy implications are also discussed.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract
The relative vast abundance and more equitable global distribution of terrestrial sodium makes sodium-ion batteries (NIBs) potentially cheaper and more sustainable alternatives to commercial ...lithium-ion batteries (LIBs). However, the practical capacities and cycle lives of NIBs at present do not match those of LIBs and have therefore hindered their progress to commercialisation. The present drawback of NIB technology stems largely from the electrode materials and their associated Na
+
ion storage mechanisms. Increased understanding of the electrochemical storage mechanisms and kinetics is therefore vital for the development of current and novel materials to realise the commercial NIB. In contrast to x-ray techniques, the non-dependency of neutron scattering on the atomic number of elements (
Z
) can substantially increase the scattering contrast of small elements such as sodium and carbon, making neutron techniques powerful for the investigation of NIB electrode materials. Moreover, neutrons are far more penetrating which enables more complex sample environments including
in situ
and
operando
studies. Here, we introduce the theory of, and review the use of, neutron diffraction and quasi-elastic neutron scattering, to investigate the structural and dynamic properties of electrode and electrolyte materials for NIBs. To improve our understanding of the actual sodium storage mechanisms and identify intermediate stages during charge/discharge,
ex situ, in situ
, and
operando
neutron experiments are required. However, to date there are few studies where
operando
experiments are conducted during electrochemical cycling. This highlights an opportunity for research to elucidate the operating mechanisms within NIB materials that are under much debate at present.
The RHIC magnet system Anerella, M; Cottingham, J; Cozzolino, J ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2003, Letnik:
499, Številka:
2
Journal Article
Recenzirano
The magnet system of the collider consists of superconducting dipole, quadrupole and correction magnets for guiding and focusing the beams through the regular arcs of the machine lattice as well as ...into collision at the six interaction points. It is designed to allow operation in the energy range 30–100
GeV/
u. Operation with either equal or unequal ion species in the colliding beams is possible, imposing a ratio of up to 2.5:1 in the magnetic fields of the two rings. There are 1740 superconducting magnets in the machine. They were designed to meet stringent requirements on field quality, reproducibility, and long-term reliability while being inexpensive to produce. Wherever feasible, production of magnets and components was carried out in industry, always with build-to-print designs. After several years of operation, no magnet has failed and the magnet system has proven reliable and functional.
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