bluuebunny/crossref_metadata_2025 huggingface dataset:
The overlooked role of pressure oscillations on heat transfer deterioration during self-sustained flow oscillations
Authors: Paul Subhanker , Paul Suparna , Fernandino Maria , Dorao Carlos Alberto
Published: December 2020

The naturally occurring oscillations during flow boiling inside a heated pipe under specific conditions are known to hinder the system performance. Although substantial research has been done to reveal the occurrence and control mechanisms of such oscillations, the heat transfer mechanism remains a puzzle to be solved. In particular, it is believed that the heat transfer deterioration can be attributed to the flow velocity variation, namely, the amplitude and period of the oscillations. Here, we show that the heat transfer deterioration does not necessarily depend on the flow velocity variation. Using controlled experiments, we investigate the underlying mechanisms of the heat transfer deterioration during flow oscillations. We show that the associated pressure oscillations play a dominant role in triggering the heat transfer deterioration. In the absence of pressure oscillations, even a high amplitude flow velocity oscillation does not deteriorate the heat transfer rates in the studied conditions.
Operando control of skyrmion density in a Lorentz transmission electron microscope with current pulses
Authors: Park Albert M. , Chen Zhen , Zhang Xiyue S. , Zhu Lijun , Muller David A. , Fuchs Gregory D.
Published: December 2020

Magnetic skyrmions hold promise for spintronic devices. To explore the dynamical properties of skyrmions in devices, a nanoscale method to image spin textures in response to a stimulus is essential. Here, we apply a technique for operando electrical current pulsing of chiral magnetic devices in a Lorentz transmission electron microscope. In ferromagnetic multilayers with interfacial Dzyaloshinskii–Moriya interaction, we study the creation and annihilation of skyrmions localized by point-like pinning sites due to defects. Using a combination of experimental and micromagnetic techniques, we establish a thermal contribution for the creation and annihilation of skyrmions in our study. Our work reveals a mechanism for controlling skyrmion density, which enables an examination of skyrmion magnetic field stability as a function of density. We find that high-density skyrmion states are more stable than low-density states or isolated skyrmions resisting annihilation over a magnetic field range that increases monotonically with density.
Hot-carrier enhanced light emission: The origin of above-threshold photons from electrically driven plasmonic tunnel junctions
Authors: Zhu Yunxuan , Cui Longji , Natelson Douglas
Published: December 2020

Understanding the origin of above-threshold photons emitted from electrically driven tunnel junctions (ℏω>eVb with Vb being the applied voltage bias) is of current interest in nano-optics and holds great promise to create novel on-chip optoelectronic and energy conversion technologies. Here, we report experimental observation and theoretical analysis of above-threshold light emission from electromigrated Au tunnel junctions. We compare our proposed hot-carrier enhanced light emission theory with existing models, including blackbody thermal radiation, multi-electron interactions, and an interpretation involving finite temperature effects. Our study highlights the key role of plasmon-induced hot carrier dynamics in emitting above-threshold photons and the need to further explore the underlying mechanisms and optimization of upconversion effects in plasmonically active nanostructures.
Phonon transport in antisite-substituted hexagonal boron nitride nanosheets: A molecular dynamics study
Authors: Zhou Man , Liang Ting , Wu Bingyang , Liu Jiaju , Zhang Ping
Published: December 2020

This study uses non-equilibrium molecular dynamics simulations to investigate the impact of antisite substitution on thermal conductivity. The phonon-dispersion curve and predicted thermal conductivity of pristine hexagonal boron nitride nanosheets (hBNNSs) show good agreement with the experiment results, indicating the reliability of the extep potential. It is clear that both neighboring substitution (NS) and random substitution (RS) drastically reduce the thermal conductivity of hBNNSs, of which RS has a larger effect. Calculations for the participation ratio and relaxation time show that the localization is the primary cause for the reduction in thermal conductivity when the defect concentration is low. When the defect concentration is higher, the primary cause is phonon-defect scattering in all phonon modes. RS has a larger effect on the phonon modes with long mean free paths, while NS has a larger effect on phonon modes with various lengths of mean free paths.
Spatial core-edge coupling of the particle-in-cell gyrokinetic codes GEM and XGC
Authors: Cheng Junyi , Dominski Julien , Chen Yang , Chen Haotian , Merlo Gabriele , Ku Seung-Hoe , Hager Robert , Chang Choong-Seock , Suchyta Eric , D'Azevedo Eduardo , Ethier Stephane , Sreepathi Sarat , Klasky Scott , Jenko Frank , Bhattacharjee Amitava , Parker Scott
Published: December 2020

Two existing particle-in-cell gyrokinetic codes, GEM for the core region and XGC for the edge region, have been successfully coupled with a spatial coupling scheme at the interface in a toroidal geometry. A mapping technique is developed for transferring data between GEM's structured and XGC's unstructured meshes. Two examples of coupled simulations are presented to demonstrate the coupling scheme. The optimization of GEM for graphics processing unit is also presented.
Analysis and prediction of shock formation in acoustic energy transfer systems
Authors: Meesala Vamsi C. , Hajj Muhammad R. , Shahab Shima
Published: December 2020

Losses associated with nonlinear wave propagation and exhibited by acoustic wave distortion and shock formation compromise the efficiency of contactless acoustic energy transfer systems. As such, predicting the shock formation distance and its dependence on the amplitude of the excitation is essential for their efficiency, design, and operation. We present an analytical approach capable of predicting the shock formation distance of acoustic waves generated by a baffled disk with arbitrary deformation in a weakly viscous fluid medium. The lossless Westervelt equation, used to model the nonlinear wave propagation, is asymptotically expanded based on the amplitude of the excitation. Because the solutions of the first- and second-order equations decay at different rates, we implement the method of renormalization and introduce a coordinate transformation to identify and eliminate the secular terms. The approach yields two partial differential equations that can be solved to predict the formation distance either analytically or numerically much faster than time-domain numerical simulations. The analysis and results are validated with solutions obtained from a nonlinear finite element simulation and previous experimental measurements.
Local characterization of a heavy-fermion superconductor via sub-Kelvin magnetic force microscopy
Authors: Wulferding Dirk , Kim Geunyong , Kim Hoon , Yang Ilkyu , Bauer E. D. , Ronning F. , Movshovich R. , Kim Jeehoon
Published: December 2020

Using magnetic force microscopy operating at sub-Kelvin temperatures, we characterize the heavy fermion superconductor CeCoIn5. We pinpoint the absolute London penetration depth of λ(0)=435 ± 20 nm and report its temperature dependence, which is closely linked to the symmetry of the superconducting gap. In addition, we directly measure the pinning force of individual Abrikosov vortices and estimate the critical current density of jc=9×104 A/cm2. In contrast to the related, well-established tunnel diode oscillator technique, our method is capable of resolving inhomogeneities locally on the micrometer scale at ultra-low temperature.
The effective isotropy of the hydrogen local potential in biphenyl and other hydrocarbons
Authors: Ulpiani Pierfrancesco , Romanelli Giovanni , Onorati Dalila , Krzystyniak Matthew , Andreani Carla , Senesi Roberto
Published: December 2020

We present an experimental investigation of the hydrogen nuclear momentum distribution in biphenyl using deep inelastic neutron scattering. Our experimental results suggest that the local potential affecting hydrogen is both harmonic and isotropic within experimental uncertainties. This feature is interpreted as a consequence of the central limit theorem, whereby the three-dimensional momentum distribution is expected to become a purely Gaussian function as the number of independent vibrational modes in a system increases. We also performed ab initio phonon calculations on biphenyl and other saturated hydrocarbons, from methane to decane. From the results of the simulations, one can observe that the nuclear momentum distribution becomes more isotropic as the number of atoms and normal modes in the molecule increases. Moreover, the predicted theoretical anisotropy in biphenyl is clearly larger than in the experiment. The reason is that the total number of normal modes necessary to reproduce the experimental results is much larger than the number of normal modes encompassed by a single unit cell due to the presence of structural disorder and intermolecular interactions in the real crystal, as well as coupling of different normal modes. Finally, experimental data were collected, over a subset of detectors on the VESUVIO spectrometer at ISIS, with a novel setup to increase the count rate and signal-to-background ratio. We envision that such an optimized experimental setup can provide faster measurements and more stringent constraints for phonon calculations.
Bouncing of cloud-sized microdroplets on superhydrophobic surfaces
Authors: Gomaa Hany , Tembely Moussa , Esmail Nabil , Dolatabadi Ali
Published: December 2020

The control of microdroplet impact on superhydrophobic surfaces (SHSs) is becoming imperative owing to its effect on several industrial applications, such as corrosion protection, self-cleaning, ice resisting, and de-icing. While most of the experimental studies on the impact dynamics of droplets are based on macrodroplets, it is unclear how the obtained results can be applied to microdroplet impact on SHSs. In this work, a comprehensive experimental analysis ranging from millimeter- to micrometer-sized droplets using a novel drop on demand microdispensing system is performed. Several SHSs were synthesized to control droplet impact by enforcing bouncing on the surface during the impingement process. The current analysis focuses on experimentally capturing and analyzing the impact behavior of cloud-sized microdroplets and macrodroplets (D0 = 10 μm–2500 μm) upon SHS impact, with hysteresis, under controlled environmental conditions. Different droplet impact parameters, such as droplet contact time, maximum spreading diameter, and restitution coefficient, were experimentally obtained. Interestingly, this investigation highlighted a contrast in the behavior of microdroplets and macrodroplets upon impact on rough SHSs. It was found that critical parameters controlling droplet dynamics, such as the maximum spreading diameter and coefficient of restitution, cannot be described by current models in the literature. A preliminary theoretical model based on energy balance and accounting for the substrate hysteresis is proposed to explain some of these findings. Finally, the effect of SHS roughness on the bouncing of cloud-sized microdroplets (D0 = 10 μm–100 μm) was examined in the context of synthesizing SHSs.
Unsteady reduced-order model of flow over cylinders based on convolutional and deconvolutional neural network structure
Authors: Peng Jiang-Zhou , Chen Siheng , Aubry Nadine , Chen Zhihua , Wu Wei-Tao
Published: December 2020

In this paper, we propose a neural network based reduced-order model for predicting the unsteady flow field over single/multiple cylinders. The neural network model constructs a mapping function between the temporal evolution of the pressure signal on the cylinder surface and the surrounding velocity field, where Convolutional Neural Network (CNN) layers are used as the encoder and deconvolutional neural network layers are used as the decoder. Compared with the network model with a fully connected (FC) decoder, the model with the deconvolution connected (DC) decoder is good for capturing and reconstructing the spatial relationships of low-rank feature spaces, such as edge intersections, parallelism, and symmetry, while the fluid flow, which is described by Navier–Stokes equations containing convection and diffusion terms, displays outstanding features of locality. In this article, the performance of the network models with the FC decoder and the DC decoder is evaluated by studying the problem of flow over a single cylinder first, and then the complexity of the flow structure of the studied problems is enhanced by increasing the number of cylinders and the Reynolds number. The results indicate that both the CNN-FC decoder model and CNN-DC decoder model achieve fast and accurate prediction on the velocity field, and the CNN-DC decoder model gives more robust and precise performance for all studied problems.
Averaging principle for stochastic differential equations under a weak condition
Authors: Guo Zhongkai , Lv Guangying , Wei Jinlong
Published: December 2020

The aim of this paper is to establish the averaging principle for stochastic differential equations under a general averaging condition, which is weaker than the traditional case. Under this condition, we establish an effective approximation for the solution of stochastic differential equations in mean square.
Surface-enhanced Raman spectroscopic investigation on adsorption kinetic of carbon monoxide at the solid–gas interface
Authors: Ge Ming , Xu Minmin , Yuan Yaxian , Guo Qinghua , Gu Renao , Yao Jianlin
Published: December 2020

A molecular-level understanding of CO adsorption behavior would be greatly beneficial to resolving the problem of CO poisoning in fuel cells and medical science. Herein, an efficient borrowing strategy based on surface enhanced Raman scattering (SERS) has been developed to investigate the adsorption behavior of CO at the gas–solid interface. A composite SERS substrate with high uniformity was fabricated by electrochemical deposition of optimal Pt over-layers onto an Au nanoparticle film. The results indicated that the linearly bonded mode follows the Langmuir adsorption curve (type I), while the multiply bonded did not. It took a longer time for the C–OM vibration to reach the adsorption equilibrium than that of C–OL. The variation tendency toward the Pt–COL frequency was in opposition to that of C–OL, caused by the chemical and dipole–dipole coupling effects. The increase in dynamic coupling effects of the CO molecules caused a blue shift in νCO and a red shift of the Pt–CO band, while its shielding effect on SERS intensity cannot be ignored. Additionally, higher pressure is more conducive for linear adsorption to achieve saturation. Density functional theory calculations were employed to explore the adsorption mechanisms. It should also be noted that the substrate with good recycling performance greatly expands its practical application value. The present study suggested that the SERS-based borrowing strategy shows sufficient even valuable capacity to investigate gas adsorption kinetics behavior.
Edge mode engineering for optimal ultracoherent silicon nitride membranes
Authors: Ivanov E. , Capelle T. , Rosticher M. , Palomo J. , Briant T. , Cohadon P.-F. , Heidmann A. , Jacqmin T. , Deléglise S.
Published: December 2020

Due to their high force sensitivity, mechanical resonators combining low mechanical dissipation with a small motional mass are highly demanded in fields as diverse as resonant force microscopy, mass sensing, or cavity optomechanics. “Soft-clamping” is a phononic engineering technique by which mechanical modes of highly stressed membranes or strings are localized away from lossy regions, thereby enabling ultrahigh-Q for ng-scale devices. Here, we report on parasitic modes arising from the finite size of the structure, which can significantly degrade the performance of these membranes. Through interferometric measurements and finite-element simulations, we show that these parasitic modes can hybridize with the localized modes of our structures, reducing the quality factors by up to one order of magnitude. To circumvent this problem, we engineer the spectral profile of the parasitic modes in order to avoid their overlap with the high-Q defect mode. We verify via a statistical analysis that the quality factors of devices fabricated with this modal engineering technique are consistently closer to the value predicted by dissipation dilution theory. We expect this method to find applications in a broad range of contexts such as optomechanical cooling, resonant force microscopy, swept-frequency sensing, or hybrid quantum networks.
Electronic structure and optical properties of quantum crystals from first principles calculations in the Born–Oppenheimer approximation
Authors: Gorelov Vitaly , Ceperley David M. , Holzmann Markus , Pierleoni Carlo
Published: December 2020

We develop a formalism to accurately account for the renormalization of the electronic structure due to quantum and thermal nuclear motions within the Born–Oppenheimer approximation. We focus on the fundamental energy gap obtained from electronic addition and removal energies from quantum Monte Carlo calculations in either the canonical or grand-canonical ensembles. The formalism applies as well to effective single electron theories such as those based on density functional theory. We show that the electronic (Bloch) crystal momentum can be restored by marginalizing the total electron–ion wave function with respect to the nuclear equilibrium distribution, and we describe an explicit procedure to establish the band structure of electronic excitations for quantum crystals within the Born–Oppenheimer approximation. Based on the Kubo–Greenwood equation, we discuss the effects of nuclear motion on optical conductivity. Our methodology applies to the low temperature regime where nuclear motion is quantized and, in general, differs from the semi-classical approximation. We apply our method to study the electronic structure of C2/c-24 crystalline hydrogen at 200 K and 250 GPa and discuss the optical absorption profile of hydrogen crystals at 200 K and carbon diamond at 297 K.
Static field homogeneity artifacts due to magnetic flux expulsion by HTS coils for high-resolution magnetic resonance imaging
Authors: Labbé Aimé , Dubuisson Rose-Marie , Ginefri Jean-Christophe , van der Beek Cornelis J. , Darrasse Luc , Poirier-Quinot Marie
Published: December 2020

High-Temperature Superconducting (HTS) radio frequency coils can greatly improve the sensitivity of Magnetic Resonance Imaging (MRI), with signal to noise ratios increased by up to 16 times. However, as homogeneity of the static field B0 is a major condition for MR acquisitions, their propensity to warp the magnetic field in their vicinity as a result of magnetic flux expulsion could cause severe image degradation. In this Letter, we report on the observation of artifacts generated by magnetic flux expulsion from a HTS coil. To that end, we acquired MR images of a water sample in the vicinity of a nonresonant HTS coil for different cooling conditions. These are zero field cooling and field cooling of the coil inside a clinical MRI bore magnet of 1.5 T, for a range of working temperatures of the HTS coil. After zero-field cooling, we observed significant artifacts in the MR images, increasing with lower temperature; images acquired after field cooling did not display these alterations. We propose a phenomenological model for the magnetic field disturbance induced by the HTS coil. This model reproduces, in good agreement with the experiments, the phase distortion observed in the MR images and allows one to extract the critical current density of the HTS coil, an important technological parameter of superconductors. Finally, we discuss the necessity of field cooling as a way to avoid these B0 inhomogeneity artifacts.
Gamma Radiation-Induced Unsaturated P(VDF-CTFE) Membranes with Improved Mechanical Properties
Authors: Wang Huazhao , Liu Yu , Xiao Yaoxin , Chen Jiafu , Xu Jinjiang , Zhang Haobin , Sun Jie , Li Jie , Zhu Chunhua , Su Jihu , Liu Feng
Published: December 2020

Poly(vinylidene fluoride-chlorotrifluoroethylene) (P(VDF-CTFE)) membranes were prepared by drop-casting with tetrahydrofuran (THF), and were then radiated by a low dose of gamma radiation without any other reagents. The apparent colour of the freshly prepared film was a semi-transparent white, which gradually darkened and finally turned black after 10.2 kGy gamma radiation. Meanwhile, the yield and breaking strength of the membrane both improved. X-Ray diffraction (XRD) spectra showed that the structure of the microcrystal of the irradiated P(VDF-CTFE)-THF membrane was not changed. FT-IR analysis showed that the structure of the newly formed double bonds was dominated by –CF2–CF=CH–CF2–, which was formed by both dehydrofluorination and dehydrochlorination. This structure was further confirmed by 1H NMR spectra. The intermediates, such a radical-containing double bonds (–(CF=CH)n–C•F–) formed in this process were traced by electron paramagnetic resonance (EPR) spectroscopy. The thermal and mechanical properties were studied by gel permeation chromatography (GPC), thermogravimetric analysis (TGA), stress–strain and dynamic mechanical analysis (DMA), and all the changes of microstructure and optimization of apparent properties were not found in the corresponding membrane prepared by a solution-cast method with ethyl acetate (EtOAc). Therefore, this paper briefly analyses the probable mechanism of using low dose of gamma radiation to improve the mechanical properties of the P(VDF-CTFE) film prepared with THF.
Upregulated LRRC55 promotes BK channel activation and aggravates cell injury in podocytes
Authors: Hu Shuai , Han Runhong , Chen Long , Qin Weisong , Xu Xiaodong , Shi Jingsong , Zhu Xiaodong , Zhang Mingchao , Zeng Caihong , Tang Zheng , Bao Hao , Liu Zhihong
Published: December 2020

Podocyte injury is a common hallmark in various glomerular diseases. The level of LRRC55 was increased in podocytes of patients with focal segmental glomerulosclerosis (FSGS), diabetic nephropathy (DN), and membranous nephropathy (MN). Upregulated LRRC55 and increased intracellular Ca2+ led to BK channel activation and the loss of intracellular potassium, resulting in apoptosome formation and caspase-3 activation in angiotensin II (Ang II)–treated podocytes. Knockout of Lrrc55 or the BK channel prevented the BK current and ameliorated podocyte injury in Ang II–treated mice. Upstream, NFATc3 regulated the expression of LRRC55. Increased LRRC55 expression in podocytes was also evident in animal models of FSGS, DN, and MN. Treatment with losartan or LRRC55 siRNA suppressed LRRC55 expression, prevented BK channel activation, and attenuated podocyte injury in animal models of FSGS, DN, and MN. In conclusion, upregulated LRRC55 promotes BK channel activation and aggravates cell injury in podocytes in FSGS, DN, and MN. LRRC55 inhibition may represent a new therapeutic approach for podocyte injury.
Gatekeepers of the fetus: Characterization of placental macrophages
Authors: Megli Christina , Coyne Carolyn B.
Published: December 2020

In this issue of JEM, Thomas et al. (https://doi.org/10.1084/jem.20200891) provide elegant technological and conceptual advances that further our understanding of the immune cells enriched at the maternal–fetal interface. Using new isolation strategies to better separate maternal- and fetal-derived cells, the authors identify previously undefined maternal-derived immune cells associated with the fetal-derived placenta and provide an in-depth analysis of the markers and characteristics of placental Hofbauer cells.
Electronic properties of carbon nanotubes as detected by photoemission and inverse photoemission
Authors: Soncini Cristian , Bondino Federica , Magnano Elena , Bhardwaj Sunil , Kumar Manvendra , Cepek Cinzia , Pedio Maddalena
Published: December 2020

The relation between morphology and energy level alignment in carbon nanotubes (CNT) is a crucial information for the optimization of applications in nanoelectronics, optics, mechanics and (bio)chemistry. Here we present a study of the relation between the electronic properties and the morphology of single wall CNT (SWCNT), aligned multi wall CNT (MWCNT) and unaligned MWCNT. The CNT were synthesized via catalytic chemical vapor deposition in ultra-high vacuum conditions. Combined ultraviolet photoemission and inverse photoemission (IPES) spectra reveal a high sensitivity to the nanotube morphology. In the case of unaligned SWCNT the distinctive unoccupied Van Hove singularities (vHs) features are observed in the high resolution IPES spectra. Those features are assigned to semiconducting and metallic SWCNT states, according to calculated vHs DOS. The two MWCNT samples are similar in the diameter of the tube (about 15 nm) and present similar filled and empty electronic states, although the measured features in the aligned MWCNT are more defined. Noteworthy, interlayer states are also revealed. Their intensities are directly related to the MWCNT alignment. Focussing and geometrical effects associated to the MWCNT alignment are discussed to account the spectral differences.
The Quantum Efficiency and Diffractive Image Artifacts of Si:As IBC mid-IR Detector Arrays at 5–10 μm: Implications for the JWST/MIRI Detectors
Authors: Gáspár András , Rieke George H. , Guillard Pierre , Dicken Daniel , Gastaud René , Alberts Stacey , Morrison Jane , Ressler Michael E. , Argyriou Ioannis , Glasse Alistair
Published: December 2020

Arsenic doped back illuminated blocked impurity band (BIBIB) silicon detectors have advanced near and mid-IR astronomy for over thirty years; they have high quantum efficiency (QE), especially at wavelengths longer than 10 μm, and a large spectral range. Their radiation hardness is also an asset for space based instruments. Three examples of Si:As BIBIB arrays are used in the Mid-InfraRed Instrument (MIRI) of the James Webb Space Telescope (JWST), observing between 5 and 28 μm. In this paper, we analyze the parameters leading to high quantum efficiency (up to ∼60%) for the MIRI devices between 5 and 10 μm. We also model the cross-shaped artifact that was first noticed in the 5.7 and 7.8 μm Spitzer/IRAC images and has since also been imaged at shorter wavelength (≤10 μm) laboratory tests of the MIRI detectors. The artifact is a result of internal reflective diffraction off the pixel-defining metallic contacts to the readout detector circuit. The low absorption in the arrays at the shorter wavelengths enables photons diffracted to wide angles to cross the detectors and substrates multiple times. This is related to similar behavior in other back illuminated solid-state detectors with poor absorption, such as conventional CCDs operating near 1 μm. We investigate the properties of the artifact and its dependence on the detector architecture with a quantum-electrodynamic (QED) model of the probabilities of various photon paths. Knowledge of the artifact properties will be especially important for observations with the MIRI LRS and MRS spectroscopic modes.
Estimating gamma and neutron radiation fluxes around BWR quivers for nuclear safeguards verification purposes
Authors: Mishra V. , Elter Zs. , Grape S. , Jansson P. , Branger E. , Vaccaro S. , Hedberg M.
Published: December 2020

Non-destructive assay (NDA) methods are at the core of nuclear safeguards verification of spent nuclear fuel (SNF). In Sweden, the spent nuclear fuel from all the reactor sites is moved to the Swedish central interim storage facility for spent nuclear fuel (for which the Swedish acronym is Clab). A new facility, Clink, is planned at the site where the SNF will undergo a safeguards verification prior to encapsulation for long-term storage. The fuel to be encapsulated includes both regular fuel assemblies as well as “non-regular” fuel assemblies including fuel objects called quivers, which are specially designed containers to house damaged or failed and leaking spent fuel rods in a way to isolate the rods from the environment and prevent contamination. The quiver concept was recently introduced in the Swedish nuclear market by Westinghouse Electric Sweden AB and it has led to some unique challenges from a safeguards verification standpoint which stem from their construction. Their overall stainless steel build, while providing robustness to the structure, also greatly diminishes the possibility of detecting gamma or neutron radiation using traditional safeguards measurement devices. The current investigation looks into the practicalities of safeguards verification of boiling water reactor (BWR) quiver objects in the spent fuel pool from above, and also assesses the possibility of their verification from the side using the widely used Fork detector. The Fork instrument has been routinely employed by both operators and inspectors around the world to verify spent fuel for routine safeguards inspections. In the present work, we model the BWR quiver and the Fork instrument in the Monte Carlo particle transport code, Serpent2 to estimate the radiation flux around the quiver objects. We have shown that the gamma and neutron radiation from the BWR quiver were heavily attenuated by the stainless steel lid and could not be relied on to make a safeguards verification from above. Furthermore, it was established that while gamma radiation from the quiver remains measurable on the sides of the quiver by the Fork instrument, the neutron counts were low compared to a typical BWR fuel assembly of similar fuel content albeit within the limits of detectability of the Fork.
Climate change mitigation through dietary change: a systematic review of empirical and modelling studies on the environmental footprints and health effects of ‘sustainable diets’
Authors: Jarmul Stephanie , Dangour Alan D , Green Rosemary , Liew Zara , Haines Andy , Scheelbeek Pauline FD
Published: December 2020

The adoption of healthy diets with low environmental impact has been widely promoted as an important climate change mitigation strategy. Typically, these diets are high in plant-sourced and low in animal-sourced and processed foods. Despite the fact that their environmental impacts vary, they are often referred to as ‘sustainable diets’. Here we systematically review the available published evidence on the effect of ‘sustainable diets’ on environmental footprints and human health. Eight databases (OvidSP-Medline, OvidSP-Embase, EBSCO-GreenFILE, Web of Science Core Collection, Scopus, OvidSP-CAB-Abstracts, OvidSP-AGRIS, and OvidSP-Global Health) were searched to identify literature (published 1999–2019) reporting health effects and environmental footprints of ‘sustainable diets’. Available evidence was mapped and pooled analysis was conducted by unique combinations of diet pattern, health and environmental outcome. Eighteen studies (412 measurements) met our inclusion criteria, distinguishing twelve non-mutually exclusive sustainable diet patterns, six environmental outcomes, and seven health outcomes. In 87% of measurements (n = 151) positive health outcomes were reported from ‘sustainable diets’ (average relative health improvement: 4.09% [95% CI −0.10–8.29]) when comparing ‘sustainable diets’ to current/baseline consumption patterns. Greenhouse gas emissions associated with ‘sustainable diets’ were on average 25.8%[95%CI −27.0 to −14.6] lower than current/baseline consumption patterns, with vegan diets reporting the largest reduction in GHG-emissions (−70.3% [95% CI: −90.2 to −50.4]), however, water use was frequently reported to be higher than current/baseline diets. Multiple benefits for both health and the environment were reported in the majority (n = 315[76%]) of measurements. We identified consistent evidence of both positive health effects and reduced environmental footprints accruing from ‘sustainable diets’. The notable exception of increased water use associated with ‘sustainable diets’ identifies that co-benefits are not universal and some trade-offs are likely. When carefully designed, evidence-based, and adapted to contextual factors, dietary change could play a pivotal role in climate change mitigation, sustainable food systems, and future population health.
Subsea permafrost carbon stocks and climate change sensitivity estimated by expert assessment
Authors: Sayedi Sayedeh Sara , Abbott Benjamin W , Thornton Brett F , Frederick Jennifer M , Vonk Jorien E , Overduin Paul , Schädel Christina , Schuur Edward A G , Bourbonnais Annie , Demidov Nikita , Gavrilov Anatoly , He Shengping , Hugelius Gustaf , Jakobsson Martin , Jones Miriam C , Joung DongJoo , Kraev Gleb , Macdonald Robie W , David McGuire A , Mu Cuicui , O’Regan Matt , Schreiner Kathryn M , Stranne Christian , Pizhankova Elena , Vasiliev Alexander , Westermann Sebastian , Zarnetske Jay P , Zhang Tingjun , Ghandehari Mehran , Baeumler Sarah , Brown Brian C , Frei Rebecca J
Published: December 2020

The continental shelves of the Arctic Ocean and surrounding seas contain large stocks of organic matter (OM) and methane (CH4), representing a potential ecosystem feedback to climate change not included in international climate agreements. We performed a structured expert assessment with 25 permafrost researchers to combine quantitative estimates of the stocks and sensitivity of organic carbon in the subsea permafrost domain (i.e. unglaciated portions of the continental shelves exposed during the last glacial period). Experts estimated that the subsea permafrost domain contains ∼560 gigatons carbon (GtC; 170–740, 90% confidence interval) in OM and 45 GtC (10–110) in CH4. Current fluxes of CH4 and carbon dioxide (CO2) to the water column were estimated at 18 (2–34) and 38 (13–110) megatons C yr−1, respectively. Under Representative Concentration Pathway (RCP) RCP8.5, the subsea permafrost domain could release 43 Gt CO2-equivalent (CO2e) by 2100 (14–110) and 190 Gt CO2e by 2300 (45–590), with ∼30% fewer emissions under RCP2.6. The range of uncertainty demonstrates a serious knowledge gap but provides initial estimates of the magnitude and timing of the subsea permafrost climate feedback.
B-Lymphoblastic Leukemia With Aberrant CD5 Expression
Authors: Ye Matthew T , Zhu Jia , Luo David X , Wang Yi , Chen Zehui , Yang Yaling , Tian Chen , Zhang Yizhuo , You M James
Published: December 2020

Objectives

B-acute lymphoblastic leukemia (B-ALL) is a neoplasm of precursor lymphoid cells committed to the B-lineage. Expression of CD5 is rare in B-ALL.

Methods

We studied the clinicopathologic, immunophenotypic, and molecular genetic features of 10 cases of B-ALL with aberrant CD5 expression, and compared with CD5–B-ALL.

Results

B-ALL with aberrant CD5 expression is rare and predominantly affects men. Patients with CD5+ B-ALL had shorter median overall survival (21 vs 45 months, P = .0003). Expression of CD5 imposed a challenge in the differential diagnoses between B-ALL and other CD5+ B-cell lymphomas with blastic morphology. Dim CD20 and CD45, lack of surface immunoglobulin, expression of CD34 and TdT, negative immunostain for cyclin D1, and absence of t(11;14)(q13;q32) support a diagnosis of B-ALL.

Conclusions

CD5 expression is rare in B-ALL and associated with poor clinical outcome. CD5+ B-ALL represents a distinct entity that needs to be considered in the differential diagnoses of CD5+ B-cell lymphoproliferative disorders.
Repurposing approved drugs for cancer therapy
Authors: Schein Catherine H
Published: December 2020

Background

Many drugs approved for other indications can control the growth of tumor cells and limit adverse events (AE).

Data sources

Literature searches with keywords ‘repurposing and cancer’ books, websites: https://clinicaltrials.gov/, for drug structures: https://pubchem.ncbi.nlm.nih.gov/

Areas of agreement

Introducing approved drugs, such as those developed to treat diabetes (Metformin) or inflammation (Thalidomide), identified to have cytostatic activity, can enhance chemotherapy or even replace more cytotoxic drugs. Also, anti-inflammatory compounds, cytokines and inhibitors of proteolysis can be used to control the side effects of chemo- and immuno-therapies or as second-line treatments for tumors resistant to kinase inhibitors (KI). Drugs specifically developed for cancer therapy, such as interferons (IFN), the tyrosine KI abivertinib TKI (tyrosine kinase inhibitor) and interleukin-6 (IL-6) receptor inhibitors, may help control symptoms of Covid-19.

Areas of controversy

Better knowledge of mechanisms of drug activities is essential for repurposing. Chemotherapies induce ER stress and enhance mutation rates and chromosome alterations, leading to resistance that cannot always be related to mutations in the target gene. Metformin, thalidomide and cytokines (IFN, tumor necrosis factor (TNF), interleukin-2 (IL-2) and others) have pleiomorphic activities, some of which can enhance tumorigenesis. The small and fragile patient pools available for clinical trials can cloud the data on the usefulness of cotreatments.

Growing points

Better understanding of drug metabolism and mechanisms should aid in repurposing drugs for primary, adjuvant and adjunct treatments.

Areas timely for developing research

Optimizing drug combinations, reducing cytotoxicity of chemotherapeutics and controlling associated inflammation.
Closed-loop stimulation of the medial septum terminates epileptic seizures
Authors: Takeuchi Yuichi , Harangozó Márk , Pedraza Lizeth , Földi Tamás , Kozák Gábor , Li Qun , Berényi Antal
Published: December 2020

Temporal lobe epilepsy with distributed hippocampal seizure foci is often intractable and its secondary generalization might lead to sudden death. Early termination through spatially extensive hippocampal intervention is not feasible directly, because of the large size and irregular shape of the hippocampus. In contrast, the medial septum is a promising target to govern hippocampal oscillations through its divergent connections to both hippocampi. Combining this ‘proxy intervention’ concept and precisely timed stimulation, we report here that closed-loop medial septum electrical stimulation can quickly terminate intrahippocampal seizures and suppress secondary generalization in a rat kindling model. Precise stimulus timing governed by internal seizure rhythms was essential. Cell type-specific stimulation revealed that the precisely timed activation of medial septum GABAergic neurons underlaid the effects. Our concept of time-targeted proxy stimulation for intervening pathological oscillations can be extrapolated to other neurological and psychiatric disorders, and has potential for clinical translation.
Connectome-Based Predictive Modeling of Individual Anxiety
Authors: Wang Zhihao , Goerlich Katharina S , Ai Hui , Aleman André , Luo Yue-jia , Xu Pengfei
Published: December 2020

Anxiety-related illnesses are highly prevalent in human society. Being able to identify neurobiological markers signaling high trait anxiety could aid the assessment of individuals with high risk for mental illness. Here, we applied connectome-based predictive modeling (CPM) to whole-brain resting-state functional connectivity (rsFC) data to predict the degree of trait anxiety in 76 healthy participants. Using a computational “lesion” approach in CPM, we then examined the weights of the identified main brain areas as well as their connectivity. Results showed that the CPM successfully predicted individual anxiety based on whole-brain rsFC, especially the rsFC between limbic areas and prefrontal cortex. The prediction power of the model significantly decreased from simulated lesions of limbic areas, lesions of the connectivity within limbic areas, and lesions of the connectivity between limbic areas and prefrontal cortex. Importantly, this neural model generalized to an independent large sample (n = 501). These findings highlight important roles of the limbic system and prefrontal cortex in anxiety prediction. Our work provides evidence for the usefulness of connectome-based modeling in predicting individual personality differences and indicates its potential for identifying personality factors at risk for psychopathology.
Influenza Vaccine Effectiveness Against All-Cause Mortality Following Laboratory-Confirmed Influenza in Older Adults, 2010–2011 to 2015–2016 Seasons in Ontario, Canada
Authors: Chung Hannah , Buchan Sarah A , Campigotto Aaron , Campitelli Michael A , Crowcroft Natasha S , Dubey Vinita , Gubbay Jonathan B , Karnauchow Timothy , Katz Kevin , McGeer Allison J , McNally J Dayre , Mubareka Samira , Murti Michelle , Richardson David C , Rosella Laura C , Schwartz Kevin L , Smieja Marek , Zahariadis George , Kwong Jeffrey C
Published: December 2020

Background

Older adults are at increased risk of mortality from influenza infections. We estimated influenza vaccine effectiveness (VE) against mortality following laboratory-confirmed influenza.

Methods

Using a test-negative design study and linked laboratory and health administrative databases in Ontario, Canada, we estimated VE against all-cause mortality following laboratory-confirmed influenza for community-dwelling adults aged >65 years during the 2010–2011 to 2015–2016 influenza seasons.

Results

Among 54 116 older adults tested for influenza across the 6 seasons, 6837 died within 30 days of specimen collection. Thirteen percent (925 individuals) tested positive for influenza, and 50.6% were considered vaccinated for that season. Only 23.2% of influenza test-positive cases had influenza recorded as their underlying cause of death. Before and after multivariable adjustment, we estimated VE against all-cause mortality following laboratory-confirmed influenza to be 20% (95% confidence interval [CI], 8%–30%) and 20% (95% CI, 7%–30%), respectively. This estimate increased to 34% after correcting for influenza vaccination exposure misclassification. We observed significant VE against deaths following influenza confirmation during 2014–2015 (VE = 26% [95% CI, 5%–42%]). We also observed significant VE against deaths following confirmation of influenza A/H1N1 and A/H3N2, and against deaths with COPD as the underlying cause.

Conclusions

These results support the importance of influenza vaccination in older adults, who account for most influenza-associated deaths annually.
Influence of Intramuscular Depot Medroxyprogesterone Acetate Initiation on Vaginal Microbiota in the Postpartum Period
Authors: Whitney Bridget M , Srinivasan Sujatha , Tapia Kenneth , Muriuki Eric Munene , Chohan Bhavna H , Wallis Jacqueline M , Liu Congzhou , Guthrie Brandon L , McClelland R Scott , Hoffman Noah G , Fredricks David N , Roxby Alison C
Published: December 2020

Background

The vaginal microbiome plays a key role in women’s reproductive health. Use of exogenous hormones, such as intramuscular depot medroxyprogesterone acetate (DMPA-IM), may alter the composition of vaginal bacterial community.

Methods

Vaginal swab samples were collected from postpartum Kenyan women initiating DMPA-IM or nonhormonal contraception (non-HC). Bacterial vaginosis was assessed by Nugent score (Nugent-BV) and bacterial community composition was evaluated using broad-range 16S ribosomal RNA gene polymerase chain reaction with high-throughput sequencing. Changes in Nugent score, alpha diversity (Shannon diversity index), and total bacterial load between contraceptive groups from enrollment to 3 months after initiation were estimated using multivariable linear mixed effects regression.

Results

Among 54 human immunodeficiency virus–negative women, 33 choosing DMPA-IM and 21 choosing non-HC, Nugent-BV was more common among DMPA-IM users at enrollment. At follow-up, Nugent score had decreased significantly among DMPA-IM users (change, −1.89; 95% confidence interval [CI], −3.53 to −.25; P = .02) while alpha diversity remained stable (0.03; −.24 to .30; P = .83). Conversely, Nugent score remained relatively stable among non-HC users (change, −0.73; 95% CI, −2.18 to .73; P = .33) while alpha diversity decreased (−0.34; −.67 to −.001; P = .05). The total bacterial load decreased slightly in DMPA-IM users and increased slightly among non-HC users, resulting in a significant difference in change between the contraceptive groups (difference, −0.64 log10 gene copies per swab sample; 95% CI, −1.19 to −.08; P = .02). While significant changes in Nugent score and alpha diversity were observed within contraceptive groups, changes between groups were not significantly different.

Conclusions

Postpartum vaginal bacterial diversity did not change in DMPA-IM users despite a reduction in Nugent-BV, but it decreased significantly among women using non-HC. Choice of contraception may influence Lactobacillus recovery in postpartum women.
Outbreak of Pseudomonas aeruginosa Infections from a Contaminated Gastroscope Detected by Whole Genome Sequencing Surveillance
Authors: Sundermann Alexander J , Chen Jieshi , Miller James K , Saul Melissa I , Shutt Kathleen A , Griffith Marissa P , Mustapha Mustapha M , Ezeonwuka Chinelo , Waggle Kady , Srinivasa Vatsala , Kumar Praveen , Pasculle A William , Ayres Ashley M , Snyder Graham M , Cooper Vaughn S , Van Tyne Daria , Marsh Jane W , Dubrawski Artur W , Harrison Lee H
Published: December 2020

Background

Traditional methods of outbreak investigations utilize reactive whole genome sequencing (WGS) to confirm or refute the outbreak. We have implemented WGS surveillance and a machine learning (ML) algorithm for the electronic health record (EHR) to retrospectively detect previously unidentified outbreaks and to determine the responsible transmission routes.

Methods

We performed WGS surveillance to identify and characterize clusters of genetically-related Pseudomonas aeruginosa infections during a 24-month period. ML of the EHR was used to identify potential transmission routes. A manual review of the EHR was performed by an infection preventionist to determine the most likely route and results were compared to the ML algorithm.

Results

We identified a cluster of 6 genetically related P. aeruginosa cases that occurred during a 7-month period. The ML algorithm identified gastroscopy as a potential transmission route for 4 of the 6 patients. Manual EHR review confirmed gastroscopy as the most likely route for 5 patients. This transmission route was confirmed by identification of a genetically-related P. aeruginosa incidentally cultured from a gastroscope used on 4of the 5 patients. Three infections, 2 of which were blood stream infections, could have been prevented if the ML algorithm had been running in real-time.

Conclusions

WGS surveillance combined with a ML algorithm of the EHR identified a previously undetected outbreak of gastroscope-associated P. aeruginosa infections. These results underscore the value of WGS surveillance and ML of the EHR for enhancing outbreak detection in hospitals and preventing serious infections.