153 research outputs found
Topical clobetasol for the treatment of toxic epidermal necrolysis: study protocol for a randomized controlled trial.
BackgroundToxic epidermal necrolysis (TEN) is a rare systemic allergic drug eruption with high patient mortality. Currently, no established treatments have been shown to be effective for TEN beyond supportive care. Prior studies of systemic corticosteroids have yielded conflicting data, with some showing a possible benefit and others reporting in increased mortality. However, topical steroids have shown promise for treatment of ocular sequelae of TEN, such as scarring and vision loss. We have designed a randomized controlled trial to evaluate topical clobetasol for treatment of the epidermal manifestations of TEN. In addition, we propose genetic studies to characterize the TEN transcriptome and alterations in cutaneous gene expression that might occur following topical steroid treatment.Methods/designThis split-body randomized, double-blind, placebo-controlled Phase IIa proof-of-concept trial will evaluate the safety and efficacy of once-daily topical clobetasol applied to the skin of patients with TEN. This multicenter trial will recruit a total of 15 patients between the ages of 12 and 85 from the University of California Davis Medical Center and Shriners Hospital for Children inpatient burn units. Designated treatment areas on opposite sides of the body will be treated with blinded clobetasol 0.05% ointment or control petrolatum ointment daily for 14 days. On day 3 of therapy, a biopsy will be taken from the treated area for genetic studies. The primary study aims will be to establish the safety of topical clobetasol treatment and determine the time to cessation of skin detachment for the control and clobetasol-treated areas. Secondary endpoints will evaluate efficacy using parameters such as time to 90% re-epithelialization and percentage of affected skin at 0, 3, 6, 9, 12 and 15 days. Genomic DNA and RNA will be obtained from biopsy samples, to characterize the TEN transcriptome and identify changes in gene expression after topical steroid treatment.DiscussionTopical steroids have shown promise for treating ocular complications of TEN, but to date have not been evaluated for cutaneous manifestations of the disease. This trial will investigate clinical and molecular outcomes of topical clobetasol application and hopefully provide insight into the disease pathophysiology.Trial registrationClinicalTrials.gov NCT02319616. https://clinicaltrials.gov/ct2/show/NCT02351037
Layer-dependent mechanical properties and enhanced plasticity in the van der Waals chromium trihalide magnets
The mechanical properties of magnetic materials are instrumental for the
development of the magnetoelastic theory and the optimization of
strain-modulated magnetic devices. In particular, two-dimensional (2D) magnets
hold promise to enlarge these concepts into the realm of low-dimensional
physics and ultrathin devices. However, no experimental study on the intrinsic
mechanical properties of the archetypal 2D magnet family of the chromium
trihalides has thus far been performed. Here, we report the room temperature
layer-dependent mechanical properties of atomically thin CrI3 and CrCl3,
finding that bilayers of CrI3 and CrCl3 have Young's moduli of 62.1 GPa and
43.4 GPa, with the highest sustained strain of 6.09% and 6.49% and breaking
strengths of 3.6 GPa and 2.2 GPa, respectively. Both the elasticity and
strength of the two materials decrease with increased thickness, which is
attributed to a weak interlayer interaction that enables interlayer sliding
under low levels of applied load. The mechanical properties observed in the
few-layer chromium trihalide crystals provide evidence of outstanding
plasticity in these materials, which is qualitatively demonstrated in their
bulk counterparts. This study will contribute to various applications of the
van der Waals magnetic materials, especially for their use in magnetostrictive
and flexible devices.Comment: Main text and supplementary informatio
EPR and optical spectroscopy of neodymium ions in KMgF3 and KZnF3 crystals
KMgF3 and KZnF3 crystals doped with Nd3+ ions were studied using EPR and optical spectroscopy methods. Several types of paramagnetic centers of Nd3+: KMgF3 - two of tetragonal and one of rhombic symmetry; KZnF3 - one of tetragonal and one of trigonal symmetry were found. Parameters of the corresponding spin Hamiltonians were determined. Using optical spectroscopy paramagnetic centers Nd2+ and Nd4+ in KMgF3 were found. © 1993 Springer
Mechanical properties of atomically thin boron nitride and the role of interlayer interactions
Atomically thin boron nitride (BN) nanosheets are important two-dimensional nanomaterials with many unique properties distinct from those of graphene, but investigation into their mechanical properties remains incomplete. Here we report that high-quality single-crystalline mono-and few-layer BN nanosheets are one of the strongest electrically insulating materials. More intriguingly, few-layer BN shows mechanical behaviours quite different from those of few-layer graphene under indentation. In striking contrast to graphene, whose strength decreases by more than 30% when the number of layers increases from 1 to 8, the mechanical strength of BN nanosheets is not sensitive to increasing thickness. We attribute this difference to the distinct interlayer interactions and hence sliding tendencies in these two materials under indentation. The significantly better interlayer integrity of BN nanosheets makes them a more attractive candidate than graphene for several applications, for example, as mechanical reinforcements
Mechanical Properties of Atomically Thin Tungsten Dichalcogenides::WS2, WSe2, and WTe2
Two-dimensional (2D) tungsten disulfide (WS), tungsten diselenide
(WSe), and tungsten ditelluride (WTe) draw increasing attention due to
their attractive properties deriving from the heavy tungsten and chalcogenide
atoms, but their mechanical properties are still mostly unknown. Here, we
determine the intrinsic and air-aged mechanical properties of mono-, bi-, and
trilayer (1-3L) WS, WSe and WTe using a complementary suite of
experiments and theoretical calculations. High-quality 1L WS has the
highest Young's modulus (302.4+-24.1 GPa) and strength (47.0+-8.6 GPa) of the
entire family, overpassing those of 1L WSe (258.6+-38.3 and 38.0+-6.0 GPa,
respectively) and WTe (149.1+-9.4 and 6.4+-3.3 GPa, respectively). However,
the elasticity and strength of WS decrease most dramatically with increased
thickness among the three materials. We interpret the phenomenon by the
different tendencies for interlayer sliding in equilibrium state and under
in-plane strain and out-of-plane compression conditions in the indentation
process, revealed by finite element method (FEM) and density functional theory
(DFT) calculations including van der Waals (vdW) interactions. We also
demonstrate that the mechanical properties of the high-quality 1-3L WS and
WSe are largely stable in the air for up to 20 weeks. Intriguingly, the
1-3L WSe shows increased modulus and strength values with aging in the air.
This is ascribed to oxygen doping, which reinforces the structure. The present
study will facilitate the design and use of 2D tungsten dichalcogenides in
applications, such as strain engineering and flexible field-effect transistors
(FETs)
Using Interpolation to Estimate System Uncertainty in Gene Expression Experiments
The widespread use of high-throughput experimental assays designed to measure the entire complement of a cell's genes or gene products has led to vast stores of data that are extremely plentiful in terms of the number of items they can measure in a single sample, yet often sparse in the number of samples per experiment due to their high cost. This often leads to datasets where the number of treatment levels or time points sampled is limited, or where there are very small numbers of technical and/or biological replicates. Here we introduce a novel algorithm to quantify the uncertainty in the unmeasured intervals between biological measurements taken across a set of quantitative treatments. The algorithm provides a probabilistic distribution of possible gene expression values within unmeasured intervals, based on a plausible biological constraint. We show how quantification of this uncertainty can be used to guide researchers in further data collection by identifying which samples would likely add the most information to the system under study. Although the context for developing the algorithm was gene expression measurements taken over a time series, the approach can be readily applied to any set of quantitative systems biology measurements taken following quantitative (i.e. non-categorical) treatments. In principle, the method could also be applied to combinations of treatments, in which case it could greatly simplify the task of exploring the large combinatorial space of future possible measurements
Target selection for the SUNS and DEBRIS surveys for debris discs in the solar neighbourhood
Debris discs - analogous to the Asteroid and Kuiper-Edgeworth belts in the
Solar system - have so far mostly been identified and studied in thermal
emission shortward of 100 um. The Herschel space observatory and the SCUBA-2
camera on the James Clerk Maxwell Telescope will allow efficient photometric
surveying at 70 to 850 um, which allow for the detection of cooler discs not
yet discovered, and the measurement of disc masses and temperatures when
combined with shorter wavelength photometry. The SCUBA-2 Unbiased Nearby Stars
(SUNS) survey and the DEBRIS Herschel Open Time Key Project are complimentary
legacy surveys observing samples of ~500 nearby stellar systems. To maximise
the legacy value of these surveys, great care has gone into the target
selection process. This paper describes the target selection process and
presents the target lists of these two surveys.Comment: 67 pages with full tables, 7 figures, accepted to MNRA
The Pioneer Anomaly
Radio-metric Doppler tracking data received from the Pioneer 10 and 11
spacecraft from heliocentric distances of 20-70 AU has consistently indicated
the presence of a small, anomalous, blue-shifted frequency drift uniformly
changing with a rate of ~6 x 10^{-9} Hz/s. Ultimately, the drift was
interpreted as a constant sunward deceleration of each particular spacecraft at
the level of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2. This apparent violation of
the Newton's gravitational inverse-square law has become known as the Pioneer
anomaly; the nature of this anomaly remains unexplained. In this review, we
summarize the current knowledge of the physical properties of the anomaly and
the conditions that led to its detection and characterization. We review
various mechanisms proposed to explain the anomaly and discuss the current
state of efforts to determine its nature. A comprehensive new investigation of
the anomalous behavior of the two Pioneers has begun recently. The new efforts
rely on the much-extended set of radio-metric Doppler data for both spacecraft
in conjunction with the newly available complete record of their telemetry
files and a large archive of original project documentation. As the new study
is yet to report its findings, this review provides the necessary background
for the new results to appear in the near future. In particular, we provide a
significant amount of information on the design, operations and behavior of the
two Pioneers during their entire missions, including descriptions of various
data formats and techniques used for their navigation and radio-science data
analysis. As most of this information was recovered relatively recently, it was
not used in the previous studies of the Pioneer anomaly, but it is critical for
the new investigation.Comment: 165 pages, 40 figures, 16 tables; accepted for publication in Living
Reviews in Relativit
The magnetic genome of two-dimensional van der Waals materials
Magnetism in two-dimensional (2D) van der Waals (vdW) materials has recently emerged as one of the most promising areas in condensed matter research, with many exciting emerging properties and significant potential for applications ranging from topological magnonics to low-power spintronics, quantum computing, and optical communications. In the brief time after their discovery, 2D magnets have blossomed into a rich area for investigation, where fundamental concepts in magnetism are challenged by the behavior of spins that can develop at the single layer limit. However, much effort is still needed in multiple fronts before 2D magnets can be routinely used for practical implementations. In this comprehensive review, prominent authors with expertise in complementary fields of 2D magnetism (i.e., synthesis, device engineering, magneto-optics, imaging, transport, mechanics, spin excitations, and theory and simulations) have joined together to provide a genome of current knowledge and a guideline for future developments in 2D magnetic materials research
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