A computational study of 1061 experimentally determined crystal structures of 508 polymorphic organic molecules has been performed with state-of-the-art lattice energy minimisation methods, using a ...hybrid method that combines density functional theory intramolecular energies with an anisotropic atom–atom intermolecular model. Rigid molecule lattice dynamical calculations have also been performed to estimate the vibrational contributions to lattice free energies. Distributions of the differences in lattice energy, free energy, zero point energy, entropy and heat capacity between polymorphs are presented. Polymorphic lattice energy differences are typically very small: over half of polymorph pairs are separated by less than 2 kJ mol −1 and lattice energy differences exceed 7.2 kJ mol −1 in only 5% of cases. Unsurprisingly, vibrational contributions to polymorph free energy differences at ambient conditions are dominated by entropy differences. The distribution of vibrational energy differences is narrower than lattice energy differences, rarely exceeding 2 kJ mol −1 . However, these relatively small vibrational free energy contributions are large enough to cause a re-ranking of polymorph stability below, or at, room temperature in 9% of the polymorph pairs.
The frequency and intensity of disasters continue to increase. Following large-scale and catastrophic disasters, local organisations integrate with other responding organisations to form hastily ...disaster relief supply chain networks. Such supply networks are infrequently activated in a single location, generate unparalleled uncertainty, change quickly, and are driven by the urgency of saving lives and restoring livelihoods. Unfortunately, even where sound supply chain management practices are used, supply networks have encountered diverse levels of resilience and adequate disaster relief performance has remained elusive. In this paper, several unique characteristics that disaster relief efforts exhibit are examined as compared with demand-driven, steady-state supply chains. Important differences in the flows of resource, money, and information are identified. A complex adaptive supply network (CASN) lens is used to frame what existing literature has uncovered regarding disaster relief efforts, showing how relief organisations, their interactions, and their environmental context help determine the level of resilience that supply networks experience following disasters. This CASN characterisation is leveraged to help explain why traditional supply chain management practices lead to varied results in disaster relief. Finally, complexity science theory is drawn on to set forth eight testable propositions that may help to enhance supply network resilience.
Wind blowing over sand on Earth produces decimeter-wavelength ripples and hundred-meter— to kilometer-wavelength dunes: bedforms of two distinct size modes. Observations from the Mars Science ...Laboratory Curiosity rover and the Mars Reconnaissance Orbiter reveal that Mars hosts a third stable wind-driven bedform, with meter-scale wavelengths. These bedforms are spatially uniform in size and typically have asymmetric profiles with angle-of-repose lee slopes and sinuous crest lines, making them unlike terrestrial wind ripples. Rather, these structures resemble fluid-drag ripples, which on Earth include water-worked current ripples, but on Mars instead form by wind because of the higher kinematic viscosity of the low-density atmosphere. A reevaluation of the wind-deposited strata in the Burns formation (about 3.7 billion years old or younger) identifies potential wind-drag ripple stratification formed under a thin atmosphere.
Background Apremilast works intracellularly to regulate inflammatory mediators. Objective ESTEEM 1 evaluated efficacy/safety of apremilast at 30 mg twice a day for moderate to severe plaque ...psoriasis. Methods This phase III, multicenter, double-blind, placebo-controlled study randomized adults (2:1) to apremilast or placebo. At week 16, the placebo group switched to apremilast through week 32, followed by a randomized treatment withdrawal phase to week 52. Binary end points were analyzed using χ2 test; continuous end points used analysis of covariance. Results In all, 844 patients were randomized (n = 282, placebo; n = 562, apremilast). At week 16, significantly more patients taking apremilast achieved 75% or greater reduction from baseline Psoriasis Area and Severity Index score (PASI-75) (33.1%) versus placebo (5.3%, P < .0001; primary end point). Most (61.0%) patients rerandomized to apremilast at week 32 achieved PASI-75 at week 52 versus 11.7% rerandomized to placebo. Of patients rerandomized to apremilast at week 32, mean percentage change from baseline PASI score was −88% to −81% (weeks 32-52). During the placebo-controlled period, 55.7% and 69.3% of patients randomized to placebo and apremilast, respectively, had 1 or more adverse events. Most adverse events were mild/moderate in severity. No new significant adverse events emerged with continued apremilast exposure versus the placebo-controlled period. Limitations Data were limited to 52 weeks and may not generalize to nonplaque psoriasis. Conclusions Apremilast was effective in moderate to severe plaque psoriasis.
Conspectus The discovery of materials capable of storing magnetic information at the level of single molecules and even single atoms has fueled renewed interest in the slow magnetic relaxation ...properties of single-molecule magnets (SMMs). The lanthanide elements, especially dysprosium, continue to play a pivotal role in the development of potential nanoscale applications of SMMs, including, for example, in molecular spintronics and quantum computing. Aside from their fundamentally fascinating physics, the realization of functional materials based on SMMs requires significant scientific and technical challenges to be overcome. In particular, extremely low temperatures are needed to observe slow magnetic relaxation, and while many SMMs possess a measurable energy barrier to reversal of the magnetization (U eff), very few such materials display the important properties of magnetic hysteresis with remanence and coercivity. Werner-type coordination chemistry has been the dominant method used in the synthesis of lanthanide SMMs, and most of our knowledge and understanding of these materials is built on the many important contributions based on this approach. In contrast, lanthanide organometallic chemistry and lanthanide magnetochemistry have effectively evolved along separate lines, hence our goal was to promote a new direction in single-molecule magnetism by uniting the nonclassical organometallic synthetic approach with the traditionally distinct field of molecular magnetism. Over the last several years, our work on SMMs has focused on obtaining a detailed understanding of why magnetic materials based on the dysprosium metallocene cation building block {Cp2Dy}+ display slow magnetic relaxation. Specifically, we aspired to control the SMM properties using novel coordination chemistry in a way that hinges on key considerations, such as the strength and the symmetry of the crystal field. In establishing that the two cyclopentadienyl ligands combine to provide a strongly axial crystal field, we were able to propose a robust magneto-structural correlation for understanding the properties of dysprosium metallocene SMMs. In doing so, a blueprint was established that allows U eff and the magnetic blocking temperature (T B) to be improved in a well-defined way. Although experimental discoveries with SMMs occur more rapidly than quantitative theory can (currently) process and explain, a clear message emanating from the literature is that a combination of the two approaches is most effective. In this Account, we summarize the main findings from our own work on dysprosium metallocene SMMs, and consider them in the light of related experimental studies and theoretical interpretations of related materials reported by other protagonists. In doing so, we aim to contribute to the nascent and healthy debate on the nature of spin dynamics in SMMs and allied molecular nanomagnets, which will be crucial for the further advancement of this vibrant research field.
The response of lean (ϕ ≤ 0.4) premixed hydrogen flames to maintained homogeneous isotropic turbulence is investigated using detailed numerical simulation in an idealised three-dimensional ...configuration over a range of Karlovitz numbers from 10 to 1562. In particular, a focus is placed on turbulence sufficiently intense that the flames can no longer be considered to be in the thin reaction burning regime. This transition to the so-called distributed burning regime is characterised through a number of diagnostics, and the relative roles of molecular and turbulent mixing processes are examined. The phenomenology and statistics of these flames are contrasted with a distributed thermonuclear flame from a related astrophysical study.
Rationale
Recent clinical trials are reporting marked improvements in mental health outcomes with psychedelic drug-assisted psychotherapy.
Objectives
Here, we report on safety and efficacy outcomes ...for up to 6 months in an open-label trial of psilocybin for treatment-resistant depression.
Methods
Twenty patients (six females) with (mostly) severe, unipolar, treatment-resistant major depression received two oral doses of psilocybin (10 and 25 mg, 7 days apart) in a supportive setting. Depressive symptoms were assessed from 1 week to 6 months post-treatment, with the self-rated QIDS-SR16 as the primary outcome measure.
Results
Treatment was generally well tolerated. Relative to baseline, marked reductions in depressive symptoms were observed for the first 5 weeks post-treatment (Cohen’s
d
= 2.2 at week 1 and 2.3 at week 5, both
p
< 0.001); nine and four patients met the criteria for response and remission at week 5. Results remained positive at 3 and 6 months (Cohen’s
d
= 1.5 and 1.4, respectively, both
p
< 0.001). No patients sought conventional antidepressant treatment within 5 weeks of psilocybin. Reductions in depressive symptoms at 5 weeks were predicted by the quality of the acute psychedelic experience.
Conclusions
Although limited conclusions can be drawn about treatment efficacy from open-label trials, tolerability was good, effect sizes large and symptom improvements appeared rapidly after just two psilocybin treatment sessions and remained significant 6 months post-treatment in a treatment-resistant cohort. Psilocybin represents a promising paradigm for unresponsive depression that warrants further research in double-blind randomised control trials.
Single-molecule magnets (SMMs) containing only one metal center may represent the lower size limit for molecule-based magnetic information storage materials. Their current drawback is that all SMMs ...require liquid-helium cooling to show magnetic memory effects. We now report a chemical strategy to access the dysprosium metallocene cation (Cp
)Dy(Cp*)
(Cp
, penta-iso-propylcyclopentadienyl; Cp
pentamethylcyclopentadienyl), which displays magnetic hysteresis above liquid-nitrogen temperatures. An effective energy barrier to reversal of the magnetization of
= 1541 wave number is also measured. The magnetic blocking temperature of
= 80 kelvin for this cation overcomes an essential barrier toward the development of nanomagnet devices that function at practical temperatures.
Volatile elements have a fundamental role in the evolution of planets. But how budgets of volatiles were set in planets, and the nature and extent of volatile-depletion of planetary bodies during the ...earliest stages of Solar System formation remain poorly understood. The Moon is considered to be volatile-depleted and so it has been predicted that volatile loss should have fractionated stable isotopes of moderately volatile elements. One such element, zinc, exhibits strong isotopic fractionation during volatilization in planetary rocks, but is hardly fractionated during terrestrial igneous processes, making it a powerful tracer of the volatile histories of planets. Here we present high-precision zinc isotopic and abundance data which show that lunar magmatic rocks are enriched in the heavy isotopes of zinc and have lower zinc concentrations than terrestrial or Martian igneous rocks. Conversely, Earth and Mars have broadly chondritic zinc isotopic compositions. We show that these variations represent large-scale evaporation of zinc, most probably in the aftermath of the Moon-forming event, rather than small-scale evaporation processes during volcanism. Our results therefore represent evidence for volatile depletion of the Moon through evaporation, and are consistent with a giant impact origin for the Earth and Moon.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We perform three‐dimensional (3‐D) numerical calculations of dynamic rupture along non‐planar faults to study the effects of fault roughness on rupture propagation and resultant ground motion. The ...fault roughness model follows a self‐similar fractal distribution over length scales spanning three orders of magnitude, from ~102 to ~105 m. The fault is governed by a strongly rate‐weakening friction, and the bulk material is subject to Drucker‐Prager viscoplasticity. Fault roughness promotes the development of self‐healing rupture pulses and a heterogeneous distribution of fault slip at the free surface and at depth. The inelastic deformation, generated by the large dynamic stress near rupture fronts, occurs in a narrow volume around the fault with heterogeneous thickness correlated to local roughness slopes. Inelastic deformation near the free surface, however, is induced by the stress waves originated from dynamic rupture at depth and spreads to large distances (>10 km) away from the fault. The present simulations model seismic wave excitation up to ~10 Hz with rupture lengths of ~100 km, permitting comparisons with empirical studies of ground‐motion intensity measures of engineering interest. Characteristics of site‐averaged synthetic response spectra, including the distance and period dependence of the median values, absolute level, and intra‐event standard deviation, are comparable to appropriate empirical estimates throughout the period range 0.1–3.0 s. This class of model may provide a viable representation of the ground‐motion excitation process over a wide frequency range in a large spatial domain, with potential applications to the numerical prediction of source‐ and path‐specific effects on earthquake ground motion.
Key Points
Fault roughness is significant in rupture dynamics and resultant ground motion
Seismic waves up to ~10 Hz are simulated with rupture lengths of ~100 km
Characteristics of synthetic ground motion are comparable to empirical estimates
PDF
