bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of high orbital angular momentum Rydberg states by optical-millimeter-wave STIRAP
Authors: Barnum T. J. , Herburger H. , Grimes D. D. , Jiang J. , Field R. W.
Published: August 2020

Rydberg states of molecules are intrinsically challenging to study due to the presence of fast non-radiative decay pathways, such as predissociation. However, selectively exciting Rydberg states with values of the orbital angular momentum (ℓ) ℓ ≳ 3 is a productive strategy to minimize this rapid decay and to populate molecular Rydberg states with lifetimes that approach those of atoms. In this proof-of-principle demonstration, we transfer population to an nf Rydberg state of the calcium atom by stimulated Raman adiabatic passage, in which an optical and a millimeter-wave field couple the initial and final states via an intermediate nd Rydberg state. Numerical simulations reproduce the observed time and frequency dependences of the population transfer and suggest the utility of this scheme to populate high-ℓ Rydberg states of molecules.
From orbitals to observables and back
Authors: Krylov Anna I.
Published: August 2020

Molecular orbital framework is of central importance in chemistry. Often used by chemists and physicists to gain insight into molecular properties, Hartree–Fock or Kohn–Sham orbitals are obtained from rather crude treatments and, strictly speaking, are not observables. Yet, quantum mechanics offers a route for connecting general many-electron wavefunctions with reduced quantities—density matrices and orbitals—which give rise to observable properties. Such mapping makes possible, in principle, reconstruction of these objects from sufficiently detailed experimental data. This Perspective discusses Dyson orbitals and various types of natural transition orbitals and illustrates their role in modeling and interpreting different types of spectroscopic measurements.
Limitations of the macrospin approximation of materials with inhomogeneous perpendicular anisotropy
Authors: Sapkota Arjun , Rai Anish , Pokhrel Ashok , Mohammadi Jamileh Beik , Li Maxwell , Lau Derek , De Graef Marc , Sokalski Vincent , Mewes Tim , Mewes Claudia
Published: August 2020

Experimental investigations of the perpendicular anisotropy in thin films that are interpreted using a macrospin model often require the inclusion of a higher-order anisotropy contribution. However, recent ferromagnetic resonance experiments on [Co/Ni]N multilayers indicate that the macrospin model cannot explain the full angular dependence in this system. Using micromagnetic simulations of a system with lateral variations of the second-order perpendicular uniaxial anisotropy, we show that while the macrospin model is able to capture the average properties of the system along high symmetry orientations by including a higher-order anisotropy, the model fails to reproduce the full angle dependence. Our studies provide another indication that higher-order anisotropies may not be intrinsic to these systems but instead may be caused by inhomogeneities.
Salivary extracellular vesicles inhibit Zika virus but not SARS‐CoV‐2 infection
Authors: Conzelmann Carina , Groß Rüdiger , Zou Min , Krüger Franziska , Görgens André , Gustafsson Manuela O , El Andaloussi Samir , Münch Jan , Müller Janis A.
Published: August 2020

Zika virus (ZIKV) is mainly transmitted via mosquitos, but human‐to‐human transmissions also occur. The virus is shed into various body fluids including saliva, which represents a possible source of viral transmission. Thus, we here explored whether human saliva affects ZIKV infectivity. We found that physiological concentrations of pooled saliva dose‐dependently inhibit ZIKV infection of monkey and human cells by preventing viral attachment to target cells. The anti‐ZIKV activity in saliva could not be abrogated by boiling, suggesting the antiviral factor is not a protein. Instead, we found that purified extracellular vesicles (EVs) from saliva inhibit ZIKV infection. Salivary EVs (saEVs) express typical EV markers such as tetraspanins CD9, CD63 and CD81 and prevent ZIKV attachment to and infection of target cells at concentrations that are naturally present in saliva. The anti‐ZIKV activity of saliva is conserved but the magnitude of inhibition varies between individual donors. In contrast to ZIKV, severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), predominantly spreading via respiratory droplets, is not affected by saliva or saEVs. Our findings provide a plausible explanation for why ZIKV transmission via saliva, i.e. by deep kissing have not been recorded and establish a novel oral innate immune defence mechanism against some viral pathogens.
A stretchable petal patterned strain sensor comprising Ir nanoparticles-modified multi-walled carbon nanotubes for human-motion detection
Authors: Teng Fu-Rui , Ren Qiang , Lai Tian-Cheng , Liu Chang , Li Ai-Dong
Published: August 2020

For flexible strain sensors, unmodified polymer substrates often have unsatisfactory performances. Herein, we report a biomimetic petal patterned polydimethylsiloxane strain sensor comprising Ir nanoparticles-modified multi-walled carbon nanotubes. Under optimal processing, the modified flexible strain sensor exhibits better comprehensive performances, such as sensitivity up to 20.33, sensing range of 0%–35%, response time of 242 ms, and more than 9000 cycles of repeated stretch–release. Moreover, it can be used for monitoring human pulse, wrist motion, and phonation. Such a facile and friendly flexible strain sensor will bring great potentials in wearable devices, human motion detection, and soft robotics.
Valley pseudospin relaxation of charged excitons in monolayer MoTe2
Authors: Smoleński T , Kazimierczuk T , Goryca M , Nogajewski K , Potemski M , Kossacki P
Published: August 2020

Zeeman effect induced by the magnetic field introduces a splitting between the two valleys at K
+ and K
− points of the Brillouin zone in monolayer semiconducting transition metal dichalcogenides. In consequence, the photoluminescence signal exhibits a field dependent degree of circular polarization. We present a comprehensive study of this effect in the case of a trion in monolayer MoTe2, showing that although time integrated data allows us to deduce a g-factor of the trion state, such an analysis cannot be substantiated by the timescales revealed in the time-resolved experiments.
Analysis of crystal structure and magnetic properties of strontium substituted bismuth ferrite thin films
Authors: Pani Tapan Kumar , Sundaray Bibekananda
Published: August 2020

Thin films of Bi(1−x)Sr
x
FeO3 (X = 0.00, 0.05, 0.10, 0.20, and 0.30) are synthesized on ultra-cleaned glass substrates by simple spray pyrolysis method at 550 °C. The crystal structures of the thin films are investigated by x-ray diffraction (XRD). The Rietveld refinement data for all the thin films are confirmed a single-phase ABO3 type of rhombohedral structure belonging to the R3c space group. The field emission scanning electron microscopy (FESEM) analysis reveals the size of grains from hexagonal to spherical shape with the addition of Sr doping. The vibrational modes are studied by Raman spectroscopy. The x-ray photoelectron spectroscopy (XPS) analysis unravels the influence of Sr2+ in the creation of Fe2+ defects and oxygen vacancies. The room temperature magnetic measurements of the thin films are carried out within a magnetic field range of ±10 kOe. Magnetic hysteresis loop confirms a significant increase in magnetization in Sr modified bismuth ferrite thin films. The composition i.e. X = 0.20 shows maximum enhancement of magnetic properties with saturation and Remanent magnetization values of 5.99 emu g−1 and 1.77 emu g−1, respectively.
High performance of filter capacitor based on nitrogen-doped carbon nanotube supercapacitor
Authors: Zhang Dazhi , Guan Yuzhu , Ji Peiyuan , Lin Shiquan , Zheng Xueli , Pu Xianjie , Liu Wenlin , Yang Renyu , Hu Chenguo , Xi Yi
Published: August 2020

The high-performance filter capacitor is a hot research topic in the field of filter circuits for flexible and wearable devices, whereas traditional aluminum electrolytic capacitors still experience widespread problems in terms of large error factors and poor stability. To avoid these disadvantages, in this work, we have developed a liquid dual-layer supercapacitor (SC). When it is employed as the filter capacitor in a filter circuit, any waveform signal can be transformed into a linear signal. The maximum fluctuation of the output signal is less than 16 mV; the SC also demonstrates excellent filtering stability in a frequency range of 1 ∼ 100 000 Hz, as well as an amplitude window of 0 ∼ 10 V. In this framework, our filter SC demonstrates unparalleled processing properties, and can greatly improve the stability and extend the lifetime of the entire electronic circuit. The fact that the requirements of high-end electronic products can be fulfilled due to the contribution of this filter SC are particularly significant.
Single-point blow-up in the Cauchy problem for the higher-dimensional Keller–Segel system
Authors: Winkler Michael
Published: August 2020

The Cauchy problem in

R

n

for the Keller–Segel system

u

t

=
Δ
u
−
∇
⋅

(

u
∇
v

)

,

v

t

=
Δ
v
−
v
+
u
,

is considered for n ⩾ 3. Using a basic theory of local existence and maximal extensibility of classical and spatially integrable solutions as a starting point, the study provides a result on the occurrence of finite-time blow-up within considerably large sets of radially symmetric initial data, and moreover verifies that any such explosion exclusively occurs at the spatial origin. The detection of blow-up is accomplished by analyzing a relative of the well-known Keller–Segel energy inequality, involving a modification of the corresponding energy functional which, unlike the latter, can be seen to be favourably controlled from below by the corresponding dissipation rate through a certain functional inequality along trajectories.
Self-focusing of linearly-polarized laser beam in the semi-bounded magnetized warm plasma: competition of right- and left-hand circularly-polarized modes
Authors: Sepehri Javan Nasser , Roozehdar Mogaddam Ramin
Published: August 2020

In this theoretical work, we study the non-linear propagation of a linearly-polarized laser beam, which is normally incident on the surface of semi-bounded magnetized warm plasma. Inside the plasma, the linearly-polarized laser beam is considered as a combination of system modes, i.e. right- and left-hand circularly-polarized modes that each behave differently. Based on a perturbative method, coupled non-linear wave equations are derived for these modes, and the problem of self-focusing is investigated. It is demonstrated that laser frequency has an essential impact on the non-linear dynamics of modes. At the frequency area where both modes can propagate, the right- and left-hand modes’ behavior is different in comparison with the uncoupled propagation of individual modes. In this case, an increase in the external magnetic field improves the focusing property of both modes.
High-energy ballistic electrons in low-pressure radio-frequency plasmas
Authors: Fu Yangyang , Zheng Bocong , Wen De-Qi , Zhang Peng , Fan Qi Hua , Verboncoeur John P
Published: August 2020

This work demonstrates the presence of a small number of high-energy ballistic electrons (HEBEs) that originate from secondary electrons in low-pressure radio-frequency (rf) plasmas. The kinetic behaviors of the HEBEs are illustrated through electron energy probability functions from the fully kinetic particle-in-cell simulations, showing two wavy high-energy tails and two bifurcations during one rf cycle. Test-particle simulations and a semi-analytical method associated with nonlocal electron kinetics are performed to characterize the HEBE trajectories, which reveal the ballistic nature of the HEBEs and their typical bouncing features between the rf sheaths. Parameter dependence of the HEBEs on the discharge conditions (e.g., gas pressure, gap distance, and rf frequency) are identified, which is relevant to the plasma collisionality. With a pronounced presence of HEBEs, the overall impacts of the secondary electron emission on discharge parameters, such as electron power absorption and ionization rate, are also illustrated.
Carrier dynamics and recombination in silicon doped InAs/GaAs quantum dot solar cells with AlAs cap layers
Authors: Kondratenko S , Kozak O , Rozouvan S , Mazur Yu I , Maidaniuk Y , Wu J , Wu S , Wang Zh M , Chan S , Kim D , Liu H , Salamo G J
Published: August 2020

The effects of doping InAs quantum dots (QDs) with Si on charge carrier dynamics and recombination in the InAs/GaAs QD solar cells (QDSCs) with AlAs cap layers was investigated. Non-radiative and radiative recombination paths in the doped cells were identified by changes in emission intensity, long-wavelength photovoltage (PV) as well as time-resolved PV and photoluminescence (PL) measurements. We find that the reduction of long-wavelength PV and PL with n-doping is due to the electron population of the QD ground states (GSs) and shrinkage of the depletion layer. The time constants, derived from the time-resolved PV, grow non-monotonically with increasing of the doping density in the QDs due to redistribution of electrostatic potential in the intrinsic region of p-i-n diode and electron population of EL2 defect states of GaAs barriers. We also find that the GS emission from the InAs QDs decreases with n-doping. The results show that PL traces depend on carrier dynamic in the top QD layers populated partially with electrons from ionized impurities, whereas PV transients were found to be strongly dependent on recombination via QD and defect states located outside the depletion layer. We conclude that the non-radiative recombination of photogenerated electrons and holes via defects is suppressed due to the spatial separation by the local electric fields in and around doped AlAs/InAs QDs, as the potential profile of the intrinsic region is modulated spatially by built-in charges. The interpretation of experimental data suggests limiting mechanisms in the InAs/GaAs QDSCs operation and sheds light on possible approaches for their further improvement.
A record-high trapped field of 5.6 T in the stacking of MgB2/TiB2 composite bulks prepared by an in-situ hot isostatic pressing method
Authors: Naito Tomoyuki , Takahashi Yuhei , Awaji Satoshi
Published: August 2020

We have studied the trapped field properties of triple and double stacking of

M
g

B
2

/

T
i

B
2

composite superconductor bulks magnetized by field-cooled magnetization. The triple-stacked

M
g

B
2

/

T
i

B
2

bulks trapped a magnetic field of 5.58 T successfully at 11.3 K, which was only 0.18 T but evidently higher than the world record trapped field of 5.4 T among

M
g

B
2

bulk magnets. We also found a potential ability of the present

M
g

B
2

/

T
i

B
2

bulks trapping a 7-T class magnetic field at low temperatures below 4.2 K, although the FCM experiments at both 2.2 and 4.2 K were disturbed by the flux jumps.
Development of a transition-edge sensor bilayer process providing new modalities for critical temperature control
Authors: Weber Joel C , Morgan Kelsey M , Yan Daikang , Pappas Christine G , Wessels Abigail L , O’Neil Galen C , Bennett Doug A , Hilton Gene C , Swetz Daniel S , Ullom Joel N , Schmidt Daniel R
Published: August 2020

Transition-edge sensors (TESs) are thermal detectors in which a superconducting film that is electrically biased in the superconducting-to-normal transition is used as a thermometer. In most TESs, the film is a superconductor-normal metal bilayer where the two materials and their thicknesses are chosen to achieve various specifications including the transition temperature Tc
. Traditionally, the materials in the bilayer are deposited in sequence without breaking vacuum in order to achieve a clean, uniform bilayer interface at the wafer-scale. This approach leads to constraints in material properties, fabrication techniques and, ultimately, TES designs. To overcome these constraints, we have developed a bilayer fabrication process that allows the layers to be deposited and patterned separately with an exposure to atmosphere between the deposition steps. We demonstrate better than 6% transition-temperature uniformity across a 7.6 cm (3 in) substrate and present satisfactory spectra from TES x-ray detectors fabricated in this fashion. We show how the new hybrid additive-subtractive TES fabrication process creates new design possibilities, including broad tuning of Tc
across a substrate with a single bilayer thickness.
From single-particle stochastic kinetics to macroscopic reaction rates: fastest first-passage time of N random walkers
Authors: Grebenkov Denis S , Metzler Ralf , Oshanin Gleb
Published: August 2020

We consider the first-passage problem for N identical independent particles that are initially released uniformly in a finite domain Ω and then diffuse toward a reactive area Γ, which can be part of the outer boundary of Ω or a reaction centre in the interior of Ω. For both cases of perfect and partial reactions, we obtain the explicit formulas for the first two moments of the fastest first-passage time (fFPT), i.e., the time when the first out of the N particles reacts with Γ. Moreover, we investigate the full probability density of the fFPT. We discuss a significant role of the initial condition in the scaling of the average fFPT with the particle number N, namely, a much stronger dependence (1/N and 1/N
2 for partially and perfectly reactive targets, respectively), in contrast to the well known inverse-logarithmic behaviour found when all particles are released from the same fixed point. We combine analytic solutions with scaling arguments and stochastic simulations to rationalise our results, which open new perspectives for studying the relevance of multiple searchers in various situations of molecular reactions, in particular, in living cells.
A minimal model for household effects in epidemics
Authors: Huber Greg , Kamb Mason , Kawagoe Kyle , Li Lucy M , Veytsman Boris , Yllanes David , Zigmond Dan
Published: August 2020

Shelter-in-place and other confinement strategies implemented in the current COVID-19 pandemic have created stratified patterns of contacts between people: close contacts within households and more distant contacts between the households. The epidemic transmission dynamics is significantly modified as a consequence. We introduce a minimal model that incorporates these household effects in the framework of mean-field theory and numerical simulations. We show that the reproduction number R
0 depends on the household size in a surprising way: linearly for relatively small households, and as a square root of size for larger households. We discuss the implications of the findings for the lockdown, test, tracing, and isolation policies.
In search of infall motion in molecular clumps II: HCO+ (1–0) and HCN (1–0) observations toward a sub-sample of infall candidates
Authors: Yang Yang , Jiang Zhi-Bo , Chen Zhi-Wei , Zhang Shao-Bo , Yu Shu-Ling , Ao Yi-Ping
Published: August 2020

Gravitational accretion accumulates the original mass. This process is crucial for us to understand the initial phases of star formation. Using the specific infall profiles in optically thick and thin lines, we searched the clumps with infall motion from the Milky Way Imaging Scroll Painting (MWISP) CO data in previous work. In this study, we selected 133 sources as a sub-sample for further research and identification. The excitation temperatures of these sources are between 7.0 and 38.5 K, while the H2 column densities are between 1021 and 1023 cm−2. We have observed optically thick lines HCO+ (1–0) and HCN (1–0) using the DLH 13.7-m telescope, and found 56 sources with a blue profile and no red profile in these two lines, which are likely to have infall motions, with a detection rate of 42%. This suggests that using CO data to restrict the sample can effectively improve the infall detection rate. Among these confirmed infall sources are 43 associated with Class 0/I young stellar objects (YSOs), and 13 which are not. These 13 sources are probably associated with the sources in the earlier evolutionary stage. In comparison, the confirmed sources that are associated with Class 0/I YSOs have higher excitation temperatures and column densities, while the other sources are colder and have lower column densities. Most infall velocities of the sources that we confirmed are between 10−1 to 100 km s−1, which is consistent with previous studies.
Recognition of FAST reflector nodes based on Canny operator
Authors: Tang Wei , Zhu Li-Chun , Wang Qi-Ming
Published: August 2020

The reflector system of Five-hundred-meter Aperture Spherical radio Telescope (FAST) is designed as 4450 rigid panels supported by a flexible cable-net structure. We use 10 total stations to measure 2225 nodes of the cable-net and then control the shape of the reflectors. Every time, it takes at least 35 minutes to finish the calibration of the whole cable-net once. It is indeed far too inefficient. Thus, we developed a set of highly efficient instrument CRRS (CCD Rotation Ranging System). It is based on photogrammetry and can finish the measurement in 1 minute. However, the target we used in CRRS is active target, and it has serious electromagnetic interference problems to affect the use of FAST. Take the above reasons into consideration, we plan to identify the nodes by taking the gap between the reflector panels as the feature condition. The new method can take the place of active targets to finish the measuring task. The present work focuses on the following aspects. First, combined with the characteristics of FAST reflector images, the representative algorithms of image edge detection are discussed. Second, the process of node extraction is introduced in detail so that we know that it works. In addition, experimental results are given to draw a conclusion so that Canny algorithm was used for continuous research of reflector edge detection.
High density carbon fiber arrays for chronic electrophysiology, fast scan cyclic voltammetry, and correlative anatomy
Authors: Patel Paras R , Popov Pavlo , Caldwell Ciara M , Welle Elissa J , Egert Daniel , Pettibone Jeffrey R , Roossien Douglas H , Becker Jill B , Berke Joshua D , Chestek Cynthia A , Cai Dawen
Published: August 2020

Objective. Multimodal measurements at the neuronal level allow for detailed insight into local circuit function. However, most behavioral studies focus on one or two modalities and are generally limited by the available technology. Approach. Here, we show a combined approach of electrophysiology recordings, chemical sensing, and histological localization of the electrode tips within tissue. The key enabling technology is the underlying use of carbon fiber electrodes, which are small, electrically conductive, and sensitive to dopamine. The carbon fibers were functionalized by coating with Parylene C, a thin insulator with a high dielectric constant, coupled with selective re-exposure of the carbon surface using laser ablation. Main results. We demonstrate the use of this technology by implanting 16 channel arrays in the rat nucleus accumbens. Chronic electrophysiology and dopamine signals were detected 1 month post implant. Additionally, electrodes were left in the tissue, sliced in place during histology, and showed minimal tissue damage. Significance. Our results validate our new technology and methods, which will enable a more comprehensive circuit level understanding of the brain.
Two-component source to explain

ΛandΛ¯

global polarization in non-central heavy-ion collisions
Authors: Ayala A , Cuautle E , Domínguez I , Maldonado I , Salinas J , Tejeda-Yeomans M E
Published: August 2020

The STAR Beam Energy Scan program has found a difference in the global polarization of

Λ

s and

Λ
¯

s produced in Au + Au collisions. This difference is larger for lower center of mass collision energies. In this work we show that a two-component source, consisting of a high density core and a lower density corona, can describe quantitatively the

Λ

and

Λ
¯

polarizations as a function of collision energy.
The atomic damping basis and the collective decay of interacting two-level atoms
Authors: Alvarez-Giron W , Barberis-Blostein P
Published: August 2020

We find analytical solutions to the evolution of interacting two-level atoms when the master equation is symmetric under the permutation of atomic labels. The master equation includes atomic independent dissipation. The method to obtain the solutions is: first, we use the system symmetries to describe the evolution in an operator space whose dimension grows polynomially with the number of atoms. Second, we expand the solutions in a basis composed of eigenvectors of the dissipative part of the master equation that models the independent dissipation of the atoms. This atomic damping basis is an atomic analog to the damping basis used for bosonic fields Briegel and Englert (1993 Phys. Rev. A 47 3311–29). The solutions show that the system decays as a sum of sub- and super-radiant exponential terms.
Shrinkage and Swelling of Greek Chestnut Wood (CastaneaSativaMill.) in Relation to Extractives Presence
Authors: Chavenetidou M , Kakavas K V , Birbilis D
Published: August 2020

The study of various woods shrinkage is of particular practical importance because the wood’s property to shrink and swell with the adsorption or absorption of moisture from the atmosphere is a main cause of many defects that occur in wood and furniture during weather conditions changing. In the present study, measurements of the shrinkage of chestnut coppice wood samples were performed before and after extraction. The extraction was carried out with hot water for 6 and 12 days. Afterwards, the dry density, radial and tangential shrinkage were determined both in air-dry conditions and in absolute dry conditions. Moreover, the fiber saturation point was determined for the selected samples. The most significant result arrived from this study is that, now, in conjunction with the other researches have been made, there is enough evidence for chestnut wood from Mediterranean coppice forests, to claim that maximum radial shrinkage is about 3.83% (ranging from 3.40% - 4.12%) and maximum tangential shrinkage is about 6.58% (ranging from 6.21% - 8.20%).
Biosynthesis of silver nanoparticles using the extracts of palm date seeds (phoenix dactylifera L.) and its application in increasing the anti-inflammatory effect of piroxicam drug
Authors: Sirry Shadia M , Ali Samah , Abdelaziz Amany , Mohamed Amr
Published: August 2020

A simple, cost-effective and eco-friendly synthesis technique of silver nanoparticles (AgNPs) using the extracts of palm date seeds (DS) and their applicability in the biomedical field have been developed. Palm date seeds (DS) were used as reducing and stabilising agents in the synthesis of silver nanoparticles (AgNPs). Different preparation techniques have been tested for the green-synthesis of AgNPs using DS extracted by different solvent media at different conditions. The solvents used were water, boiling water, acidic media, alkaline media, methanol and ethanol. The formation of AgNPs was confirmed using surface plasmon resonance band (SPR) at λ = 450 nm. Water and alkaline DS extracts have given high absorbance of well-defined SPR band. On contrary, acidic extracts have given random SPR with weak absorbance. DS extracts obtained using boiling water have shown small and broad absorbance of SPR band. It was found that the formation of AgNPs in water was more efficient than in methanol and ethanol. AgNPs were characterised by TEM. In addition, AgNPs have been used as a carrier for piroxicam anti-inflammatory drug and were characterised using FTIR. The anti-inflammatory effect of piroxicam-loaded AgNPs has been studied using the inhibition of albumin denaturation and has shown a considerable increase in protein denaturation inhibition (34.1% I) if compared to the standard piroxicam’s 19.9% inhibition.
Biosynthesis of Zinc oxide nanoparticles and their application for antimicrobial treatment of burn wound infections
Authors: Wang Peng , Jiang Lei , Han Rongxia
Published: August 2020

The current study demonstrated the green fabrication of Zinc oxide nanoparticles (ZnO NPs) using the leaf extract of Coleus amboinicus (C. amboinicus) by an environment-friendly method. The leaf extract of C. amboinicus acts as capping and reducing agent during the fabrication of ZnO NPs. The prepared ZnO NPs were characterized by utilizing analytical techniques such as photoluminescence spectroscopy (PL), Transmission Electron microscopy (TEM), Energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy (UV–vis) and x-ray diffraction spectroscopy (XRD). The XRD pattern confirmed the formation of polydisperse ZnO NPs having crystalline nature. The FTIR spectrum demonstrated the biomolecular capping on the surface of zinc oxide nanoparticles. The prepared ZnO NPs displayed excellent antimicrobial activities over several gram positive and gram-negative microbial pathogens. Further, wound healing studies in rats revealed that wound closure rate was greater in the ZnO NPs treated rats at all doses when related with the untreated group (negative control group), therefore, this indicates the effective wound healing ability of prepared ZnO NPs.
Energy-absorbing wood composite for improved damage tolerance inspired by mollusc shells
Authors: Pramreiter Maximilian , Rohner Martin , Kumpenza Cedou , Ungerer Bernhard , Stadlmann Alexander , Keckes Jozef , Müller Ulrich
Published: August 2020

The crossed lamellar structure (CLS) found in mollusc shells is an excellent example for nature’s ability to form complex hierarchical microstructures with a remarkable balance between strength and toughness. The CLS has become the subject of numerous studies focusing on the replication of the unique microstructure using synthetic composites. The present study proposes a wood composite replicating the CLS’ middle layer microstructure and investigates the mechanical properties using three-point bending tests. The morphology of the failure mechanisms is recorded using digital microscopy and the experimental data are compared to those from ply- and solid woods. The results show a successful replication of the dominating failure mechanisms of crack deflection and crack bridging. While strength decreased significantly by ∼60%, toughness increased remarkable by ∼70% compared to plywood and was in the range of solid wood. The small data scattering from the wooden CLS samples compared to solid wood further hints on a stable failure mechanism and uniform energy-absorption. The results document that wood can be used to design an energy-absorbing composite based on the CLS-inspired ductile microstructure.
Quantifying the influence of calcium ion concentration on the corrosion of high-purity magnesium, AZ91, WE43 in modified Hanks’ solutions
Authors: Py Baptiste , Johnston Sean , Hardy Alexander , Shi Zhiming , Wolski Krzysztof , Atrens Andrej
Published: August 2020

The corrosion rate in a modified Hanks’ solution (containing no Ca2+ ions) was higher than in Hanks’ solution. The increase was by a factor of ∼12 for HP Mg and AZ91, and a factor of ∼6 for WE43. This quantitatively highlights the critical role of Ca2+ ions for Mg corrosion in synthetic body fluids. The Ca2+ ion containing solutions produced a dense corrosion-product layer of hydroxyapatite, Ca3(PO4)2) · Ca(OH)2, a greater fraction of which stayed on the corroding surface (∼0.2–0.3) compared with the Ca2+ ion free solutions which produced magnesium phosphate, Mg3(PO4)2.
Role and value of flexibility in facilitating cost-effective energy system decarbonisation
Authors: Strbac Goran , Pudjianto Danny , Aunedi Marko , Djapic Predrag , Teng Fei , Zhang Xi , Ameli Hossein , Moreira Roberto , Brandon Nigel
Published: August 2020

Decarbonisation of the electricity system requires significant and continued investment in low-carbon energy sources and electrification of the heat and transport sectors. With diminishing output and shorter operating hours of conventional large-scale fossil fuel generators, there is a growing need and opportunity for other emerging technologies to provide flexibility in the context of grid support, balancing, security services, and investment options to support a cost-effective transition to a lower-carbon energy system. This article summarises the key findings from a range of studies investigating the potential benefits and challenges associated with the future low-carbon energy system. The key challenges associated with balancing local, national and regional objectives to minimise the overall cost of decarbonising the future energy system are also discussed. Furthermore, the paper highlights the importance of cross-energy vector flexibility, and coordination across electricity, heat, and gas systems which is critical for shaping the future low-carbon energy systems. Although most of the case studies presented in this article are based on the UK, and to some extent the EU decarbonisation pathways, the overall conclusions regarding the value of flexibility are relevant for the global energy transition.
Generalizability issues with deep learning models in medicine and their potential solutions: illustrated with cone-beam computed tomography (CBCT) to computed tomography (CT) image conversion
Authors: Liang Xiao , Nguyen Dan , Jiang Steve B
Published: August 2020

Generalizability is a concern when applying a deep learning (DL) model trained on one dataset to other datasets. It is challenging to demonstrate a DL model’s generalizability efficiently and sufficiently before implementing the model in clinical practice. Training a universal model that works anywhere, anytime, for anybody is unrealistic. In this work, we demonstrate the generalizability problem, then explore potential solutions based on transfer learning by using the cone-beam computed tomography (CBCT) to computed tomography (CT) image conversion task as the testbed. Previous works only studied on one or two anatomical sites and used images from the same vendor’s scanners. Here, we investigated how a model trained for one machine and one anatomical site works on other machines and other anatomical sites. We trained a model on CBCT images acquired from one vendor’s scanners for head and neck cancer patients and applied it to images from another vendor’s scanners and for prostate, pancreatic, and cervical cancer patients. We found that generalizability could be a significant problem for this particular application when applying a trained DL model to datasets from another vendor’s scanners. We then explored three practical solutions based on transfer learning to solve this generalization problem: the target model, which is trained on a target dataset from scratch; the combined model, which is trained on both source and target datasets from scratch; and the adapted model, which fine-tunes the trained source model to a target dataset. We found that when there are sufficient data in the target dataset, all three models can achieve good performance. When the target dataset is limited, the adapted model works the best, which indicates that using the fine-tuning strategy to adapt the trained model to an unseen target dataset is a viable and easy way to implement DL models in the clinic.
On a quaternionic Picard theorem
Authors: Bisi Cinzia , Winkelmann Jörg
Published: August 2020

The classical theorem of Picard states that a non-constant holomorphic function

f
:

C

→

C

f:\mathbb {C}\to \mathbb {C}

can avoid at most one value.

We investigate how many values a non-constant slice regular function of a quaternionic variable

f
:

H

→

H

f:\mathbb {H}\to \mathbb {H}

may avoid.
Is the History of Childhood Ready for the World? A Response to “The Kids Aren’t All Right”
Authors: Pande Ishita
Published: August 2020

In a complement to the 2020 AHR Roundtable “Chronological Age: A Useful Category of Historical Analysis” (125, no. 2), this AHR Exchange focuses on the history of children and childhood. Sarah Maza presents a critical review essay, highlighting the limiting factors in the expanding field of childhood studies. Children, she observes, produce few sources of their own voices, have limited agency, and as individuals and as a group soon outgrow their subaltern status—they grow up. Robin P. Chapdelaine, Nara Milanich, Steven Mintz, Ishita Pande, and Bengt Sandin—historians representing diverse geographical, theoretical, and methodological perspectives on the history of children and childhood—react to Maza’s observations by bringing up important methodological questions about subjecthood, agency, and modernity. Maza’s rejoinder reflects on these questions and on the possibility of age-based historical agency.
A Quantitative Retrospective Exposure Assessment for Former Chrysotile Asbestos Miners and Millers from Baie Verte, NL, Canada
Authors: Giles Murphy Tina , Bornstein Stephen , Oudyk John , Demers Paul A
Published: August 2020

Despite numerous studies of asbestos workers in the epidemiologic literature, there are very few cohort studies of chrysotile asbestos miners/millers that include high-quality retrospective exposure assessments. As part of the creation of the Baie Verte Miners’ Registry in 2008, a two-dimensional job exposure matrix (JEM) was developed for estimating asbestos exposures for former chrysotile asbestos miners/millers. Industrial hygiene data collected between 1963 and 1994 were analysed to assess validity for use in a retrospective exposure assessment and epidemiologic study. Registered former employees were divided into 52 exposure groups (EGs) based on job title and department and mean asbestos concentrations were calculated for each EG. The resulting exposure estimates were linked to individual registrants’ work histories allowing for the calculation of cumulative asbestos exposure for each registrant. The distribution of exposure for most EGs (82.6%) could be described as fitting a log-normal distribution, although variability within some EGs (55%) exceeded a geometric standard deviation (GSD) of 2.5. Overall, the data used to create EGs in the development of the JEM were deemed to be of adequate quality for estimating cumulative asbestos exposures for the former employees of the Baie Verte asbestos mine/mill. The variability between workers in the same job was often high and is an important factor to be considered when using estimates of cumulative asbestos exposure to adjudicate compensation claims. The exposures experienced in this cohort were comparable to those of other chrysotile asbestos miners/millers cohorts, specifically Italian and Québec cohorts.
Synthetic observations from deep generative models and binary omics data with limited sample size
Authors: Nußberger Jens , Boesel Frederic , Lenz Stefan , Binder Harald , Hess Moritz
Published: August 2020

Deep generative models can be trained to represent the joint distribution of data, such as measurements of single nucleotide polymorphisms (SNPs) from several individuals. Subsequently, synthetic observations are obtained by drawing from this distribution. This has been shown to be useful for several tasks, such as removal of noise, imputation, for better understanding underlying patterns, or even exchanging data under privacy constraints. Yet, it is still unclear how well these approaches work with limited sample size. We investigate such settings specifically for binary data, e.g. as relevant when considering SNP measurements, and evaluate three frequently employed generative modeling approaches, variational autoencoders (VAEs), deep Boltzmann machines (DBMs) and generative adversarial networks (GANs). This includes conditional approaches, such as when considering gene expression conditional on SNPs. Recovery of pair-wise odds ratios (ORs) is considered as a primary performance criterion. For simulated as well as real SNP data, we observe that DBMs generally can recover structure for up to 300 variables, with a tendency of over-estimating ORs when not carefully tuned. VAEs generally get the direction and relative strength of pairwise relations right, yet with considerable under-estimation of ORs. GANs provide stable results only with larger sample sizes and strong pair-wise relations in the data. Taken together, DBMs and VAEs (in contrast to GANs) appear to be well suited for binary omics data, even at rather small sample sizes. This opens the way for many potential applications where synthetic observations from omics data might be useful.
The Quaternary range dynamics ofNoccaea iberidea(Brassicaceae), a typical representative of subalpine/alpine steppe communities of Anatolian mountains
Authors: Özüdoğru Bariş , Özgi̇şi Kurtuluş , Perktaş Utku , Gür Hakan
Published: August 2020

The responses of Anatolian plants to global climate change have been poorly investigated. In this study, we aimed to understand how climatic oscillation during the Quaternary period helped to shape the current distribution patterns of the Anatolian endemic Noccaea iberidea, a typical representative of tragacanthic (thorny cushion) steppe communities of Anatolia. We used ecological niche modelling combined with statistical phylogeography, based on nuclear ribosomal ITS and plastidic trnL-F and trnS-ycf9 regions. Both the structure of the haplotype networks and the results of the extended Bayesian skyline plot analysis clearly indicated that N. iberidea has been through a recent population expansion. This interpretation was also supported by ecological niche modelling analysis, which showed that the availability of areas of high suitability expanded from the Last Interglacial to the Last Glacial Maximum, suggesting that N. iberidea might have expanded its range during the glacial periods. In conclusion, the study improves our understanding of the demographic history and responses of steppe plant communities of Anatolia to global climate changes through the Late Quaternary glacial–interglacial cycles, which in turn might aid in the development of future conservation strategies.
Regional Alterations in Cortical Sulcal Depth in Living Fetuses with Down Syndrome
Authors: Yun Hyuk Jin , Perez Juan David Ruiz , Sosa Patricia , Valdés J Alejandro , Madan Neel , Kitano Rie , Akiyama Shizuko , Skotko Brian G , Feldman Henry A , Bianchi Diana W , Grant P Ellen , Tarui Tomo , Im Kiho
Published: August 2020

Down syndrome (DS) is the most common genetic cause of developmental disabilities. Advanced analysis of brain magnetic resonance imaging (MRI) has been used to find brain abnormalities and their relationship to neurocognitive impairments in children and adolescents with DS. Because genetic factors affect brain development in early fetal life, there is a growing interest in analyzing brains from living fetuses with DS. In this study, we investigated regional sulcal folding depth as well as global cortical gyrification from fetal brain MRIs. Nine fetuses with DS (29.1 ± 4.24 gestational weeks [mean ± standard deviation]) were compared with 17 typically developing [TD] fetuses (28.4 ± 3.44). Fetuses with DS showed lower whole-brain average sulcal depths and gyrification index than TD fetuses. Significant decreases in sulcal depth were found in bilateral Sylvian fissures and right central and parieto-occipital sulci. On the other hand, significantly increased sulcal depth was shown in the left superior temporal sulcus, which is related to atypical hemispheric asymmetry of cortical folding. Moreover, these group differences increased as gestation progressed. This study demonstrates that regional sulcal depth is a sensitive marker for detecting alterations of cortical development in DS during fetal life, which may be associated with later neurocognitive impairment.
Dynamic Neural Interactions Supporting the Cognitive Reappraisal of Emotion
Authors: Steward Trevor , Davey Christopher G , Jamieson Alec J , Stephanou Katerina , Soriano-Mas Carles , Felmingham Kim L , Harrison Ben J
Published: August 2020

The cognitive reappraisal of emotion is hypothesized to involve frontal regions modulating the activity of subcortical regions such as the amygdala. However, the pathways by which structurally disparate frontal regions interact with the amygdala remains unclear. In this study, 104 healthy young people completed a cognitive reappraisal task. Dynamic causal modeling (DCM) was used to map functional interactions within a frontoamygdalar network engaged during emotion regulation. Five regions were identified to form the network: the amygdala, the presupplementary motor area (preSMA), the ventrolateral prefrontal cortex (vlPFC), dorsolateral prefrontal cortex (dlPFC), and ventromedial prefrontal cortex (vmPFC). Bayesian Model Selection was used to compare 256 candidate models, with our winning model featuring modulations of vmPFC-to-amygdala and amygdala-to-preSMA pathways during reappraisal. Moreover, the strength of amygdala-to-preSMA modulation was associated with the habitual use of cognitive reappraisal. Our findings support the vmPFC serving as the primary conduit through which prefrontal regions directly modulate amygdala activity, with amygdala-to-preSMA connectivity potentially acting to shape ongoing affective motor responses. We propose that these two frontoamygdalar pathways constitute a recursive feedback loop, which computes the effectiveness of emotion-regulatory actions and drives model-based behavior.
Reduction in Expected Survival Associated With Nontuberculous Mycobacterial Pulmonary Disease
Authors: Mourad Ahmad , Baker Arthur W , Stout Jason E
Published: August 2020

Background

Nontuberculous mycobacteria (NTM) are opportunistically pathogenic bacteria that are found abundantly in the soil and water. Susceptible individuals exposed to NTM-containing aerosols from environmental sources may develop NTM pulmonary disease (NTM-PD). Reported survival after NTM-PD diagnosis varies widely among existing studies. Prior work has suggested that mortality among persons with NTM-PD is primarily driven by comorbidities rather than NTM-PD.

Methods

We retrospectively identified a cohort of patients in the Duke University Health System who were diagnosed with NTM-PD between 1996 and 2015. Hospitalizations and survival were compared among patients with NTM-PD with and without other comorbidities. Additionally, survival among patients with NTM-PD was compared with standardized mortality data for a similar cohort of the general population.

Results

Patients with NTM-PD without other comorbidities had 0.65 hospitalizations/1000 patient-days compared with 1.37 hospitalizations/1000 patient-days for patients with other comorbidities. Compared with a cohort of the general population, expected survival decreased by approximately 4 years for a diagnosis of NTM-PD without comorbidities and 8.6 years for a diagnosis of NTM-PD with comorbidities. Mortality 5 years after diagnosis was 25.0% and 44.9% among NTM patients without and with comorbidities, respectively, compared with 5.7% in the general-population cohort.

Conclusions

NTM-PD was associated with significant morbidity that was worse in patients with comorbidities. Patients with NTM-PD, even without comorbidities, had worse survival than expected.