bluuebunny/crossref_metadata_2025 huggingface dataset:
Chronic Lung Allograft Dysfunction: Evolving Concepts and Therapies
Authors: Amubieya Olawale , Ramsey Allison , DerHovanessian Ariss , Fishbein Gregory A. , Lynch Joseph P. , Belperio John A. , Weigt S. Samuel
Published: May 2021

The primary factor that limits long-term survival after lung transplantation is chronic lung allograft dysfunction (CLAD). CLAD also impairs quality of life and increases the costs of medical care. Our understanding of CLAD continues to evolve. Consensus definitions of CLAD and the major CLAD phenotypes were recently updated and clarified, but it remains to be seen whether the current definitions will lead to advances in management or impact care. Understanding the potential differences in pathogenesis for each CLAD phenotype may lead to novel therapeutic strategies, including precision medicine. Recognition of CLAD risk factors may lead to earlier interventions to mitigate risk, or to avoid risk factors all together, to prevent the development of CLAD. Unfortunately, currently available therapies for CLAD are usually not effective. However, novel therapeutics aimed at both prevention and treatment are currently under investigation. We provide an overview of the updates to CLAD-related terminology, clinical phenotypes and their diagnosis, natural history, pathogenesis, and potential strategies to treat and prevent CLAD.
Investigation of the application of a magnetic abrasive finishing process using an alternating magnetic field for finishing micro-grooves
Authors: Xie Huijun , Zou Yanhua
Published: May 2021

A magnetic abrasive finishing process using an alternating magnetic field is proposed for the finishing of complex surfaces. In an alternating field, the periodic changes in current will cause the magnetic cluster used as a magnetic brush to fluctuate, which will not only continuously replace the abrasive particles in contact with the workpiece, but also periodically adjust the shape of the magnetic cluster to better fit the surface of the workpiece. In this paper, the influence of a combination of alternating and static magnetic fields on the magnetic field in the finishing area is analyzed. The feasibility of this process for finishing micro-grooves is investigated. Simulations and experimental measurements show that the combination of alternating and static magnetic fields can retain the advantages of the alternating field while increasing the magnetic flux density in the finishing area. The experimental results show that the process is feasible for finishing micro-grooves, with an excellent deburring effect on the groove edges.
Fluid dynamics analysis and experimental study for solar radiation error correction of sounding humidity sensor
Authors: Zhang Jiahong , Xie Xiaolu , Liu Qingquan , Li Min , Mao Xiaoli
Published: May 2021

In order to correct the solar radiation error of relative humidity, the mainstream capacitive sounding humidity sensor HC103M2 is selected and investigated by simulation analysis and experimental verification. First, the basic theories for solar radiation error and sensor error itself are elaborated, and simulational and experimental platforms are introduced. The computational fluid dynamics (CFD) method is utilized to theoretically investigate the dry error of the humidity sensor caused by solar radiation heating, which is related to radiation intensity, altitude, and solar elevation angle as well as reflectivity, thickness, and shape of the shield. Then, in order to verify the accuracy of the simulation, an experimental platform including a humidity sensor and two temperature sensors to measure the solar radiation heating is built to analyze the relative error of humidity obtained by the CFD simulation and experiment. It is found that their maximum deviation is 3.30% and the average error is 1.94%, which indicates that the calculation using the CFD method is accurate and feasible. In order to easily and operationally predict the solar radiation heating of the humidity sensor, a back propagation (BP) neural network fusion algorithm based on three inputs of radiation intensity, air pressure, and solar elevation angle is proposed. Compared with the solar radiation heating obtained by CFD simulation, the maximum absolute error is about 0.2 K, and the relative error of humidity is about ±1.30%. Finally, a case of vertical humidity profile correction considering the temperature-sensitive error of HC103M2 is analyzed. The response time of sensor measurement and the airflow into the shield are discussed as well. The corrected results after taking solar radiation heating into account are more similar to those measured by RS92 and cryogenic frost point hygrometer (CFH). This result shows that the prediction model is accurate, which may be applied to correct the dry error and further improve the accuracy of humidity measurement.
Building intuition for binding free energy calculations: Bound state definition, restraints, and symmetry
Authors: Duboué-Dijon E. , Hénin J.
Published: May 2021

The theory behind computation of absolute binding free energies using explicit-solvent molecular simulations is well-established, yet somewhat complex, with counter-intuitive aspects. This leads to frequent frustration, common misconceptions, and sometimes erroneous numerical treatment. To improve this, we present the main practically relevant segments of the theory with constant reference to physical intuition. We pinpoint the role of the implicit or explicit definition of the bound state (or the binding site) to make a robust link between an experimental measurement and a computational result. We clarify the role of symmetry and discuss cases where symmetry number corrections have been misinterpreted. In particular, we argue that symmetry corrections as classically presented are a source of confusion and could be advantageously replaced by restraint free energy contributions. We establish that contrary to a common intuition, partial or missing sampling of some modes of symmetric bound states does not affect the calculated decoupling free energies. Finally, we review these questions and pitfalls in the context of a few common practical situations: binding to a symmetric receptor (equivalent binding sites), binding of a symmetric ligand (equivalent poses), and formation of a symmetric complex, in the case of homodimerization.
Design and performance of a hyperspectral camera for full-face in vivo imaging
Authors: Blaksley C. , Casolino M. , Cambié G.
Published: May 2021

Red, green, blue color photography is a mature technology and a powerful tool for the evaluation and understanding of the way an object reflects light and its related optical properties, but color photography fails to give a complete picture of these effects due to its inherent lack of spectral resolution. In this work, we update the L’OREAL reference device for skin color measurement, the Chromasphere, by replacing its current color camera system with an imaging spectrometer. This imaging spectrometer must provide a spatial resolution on par with the previous color cameras and a spectral resolution commensurate with a spectroradiometer while also achieving a time resolution suitable for in vivo studies of the human face. Due to these requirements, common spatial scanning techniques are not suitable for this application, and so we utilized a spectral-scanning approach based on a tunable liquid-crystal birefringent filter. We present the design and performance tests of a working prototype that is capable of measuring the spectrum in each of 4 MP with a nominal spectral resolution of 10 nm across the wavelength range from 420 to 730 nm in a total imaging time of less than 10 s. We cross-compared the spectral and color measurements obtained with this prototype, an industry-standard spectroradiometer, and a charge-coupled device color camera in order to assess the prototype’s performance, and the results of this comparison show that our prototype is capable of taking spectral measurements near enough in quality to those of a spectroradiometer to successfully bridge the divide between such devices and conventional color cameras. Doing so, this instrument opens new possibilities for studies of complex in vivo phenomena that neither non-imaging spectrometers nor conventional cameras can pursue.
A theoretical self-consistent method for the dislocation-based heterojunction
Authors: Wang Shaofeng
Published: May 2021

As an improvement of the conventional misfit dislocation theory, a theoretical self-consistent method is presented for a study of the heterojunction. Although the interaction between two adhesive crystals is still effectively described by the γ-energy function, however, the period appearing in the γ-energy function is no longer predetermined as is usually done but treated as a parameter needs to be determined in a self-consistent way. Because the period is actually the Burgers vector of the misfit dislocation, the self-consistent method is significant for the dislocation-based heterojunction theory. As an illustration, the theory is applied to the heterojunction of two-dimensional materials AlN and BN. It is found that for the AlN/BN heterojunction, the period determined from the minimum-energy principle is very close to the value given previously.
Measurement and characterization of nanosecond laser driven shockwaves utilizing photon Doppler velocimetry
Authors: Bovid Stanley , Clauer Allan , Kattoura Micheal , Vivek Anupam , Daehn Glenn , Niezgoda Stephen
Published: May 2021

Laser driven shockwaves from nanosecond pulsed lasers were evaluated for pressure magnitude and duration using photon Doppler velocimetry (PDV). Specific investigations were performed on Ti-6Al-4V alloys and 7085-T7651 aluminum alloys with laser full-width half-max pulse lengths ranging from 6 to 20 ns and laser intensities of 2–10 GW/cm2. The rear surface velocity data obtained using a heterodyne PDV system and an automated signal processing algorithm are demonstrated and utilized to capture rear surface velocity profiles. Peak shockwave pressures measured under bare surface water confinement reached approximately 6 GPa. Shockwave loading durations were observed to correspond with laser pulse durations with impulse loading times on the order of 2×–4× the laser pulse duration.
Flexoelectric characterization of dielectrics under tensile, compressive, and flexural loads by non-contact Kelvin probe measurements
Authors: Lorenzett Ezequiel , Moreira Kelly S. , Santos da Campo Yan A. , Mehler Dylan , Devens Ana Luisa , Noras Maciej A. , Burgo Thiago A. L.
Published: May 2021

Non-contact electrostatic measurements were used to the characterization of flexoelectric potentials in dielectrics under tensile, compressive, and flexural loads. Kelvin probes are capable to detect localized potential gradients on stretched natural latex that would hardly be detected at the macroscopic scale using standard methods for flexoelectric characterization. The high deformability of rubbers under tensile (or compressive) loads or dielectrics in fully folded states during flexural tests is a really challenging task for measurements using attached or compliant electrodes to detect flexoelectricity but is easily assessed with Kelvin probes. Moreover, non-contact electrostatic measurements are effective to avoid triboelectric effects, which are important sources of electricity on contacting surfaces.
When bigger is faster: A self-Van Hove analysis of the enhanced self-diffusion of non-commensurate guest particles in smectics
Authors: Lettinga M. Paul , Alvarez Laura , Korculanin Olivera , Grelet Eric
Published: May 2021

We investigate the anomalous dynamics in smectic phases of short host rods where, counter-intuitively, long guest rod-shaped particles diffuse faster than the short host ones due to their precise size mismatch. In addition to the previously reported mean-square displacement, we analyze the time evolution of the self-Van Hove functions G(r, t), as this probability density function uncovers intrinsic heterogeneous dynamics. Through this analysis, we show that the dynamics of the host particles parallel to the director becomes non-Gaussian and therefore heterogeneous after the nematic-to-smectic-A phase transition, even though it exhibits a nearly diffusive behavior according to its mean-squared displacement. In contrast, the non-commensurate guest particles display Gaussian dynamics of the parallel motion, up to the transition to the smectic-B phase. Thus, we show that the self-Van Hove function is a very sensitive probe to account for the instantaneous and heterogeneous dynamics of our system and should be more widely considered as a quantitative and complementary approach of the classical mean-squared displacement characterization in diffusion processes.
Polarization induced interface and electron sheet charges of pseudomorphic ScAlN/GaN, GaAlN/GaN, InAlN/GaN, and InAlN/InN heterostructures
Authors: Ambacher O. , Christian B. , Yassine M. , Baeumler M. , Leone S. , Quay R.
Published: May 2021

The piezoelectric and spontaneous polarization of wurtzite ScxAl1−xN, GaxAl1−xN, and InxAl1−xN ternary compounds dramatically affects the electrical properties of pseudomorphic MexAl1−xN/GaN, MexAl1−xN/AlN, and MexAl1−xN/InN heterostructures and devices (Me: = Sc, Ga, In), due to bound interface charges caused by gradients in polarization at surfaces and heterointerfaces. We have calculated the piezoelectric and spontaneous polarization of undoped, metal polar ScxAl1−xN barrier layers (0 ≤ x ≤ 0.5) pseudomorphically grown on InN, GaN, and AlN buffer layers, in order to compare the polarization induced surface and interface charges determined to the ones predicted and measured in heterostructures with GaxAl1−xN and InxAl1−xN barriers (0 ≤ x ≤ 1.0). To facilitate the inclusion of the predicted polarization in future simulations, we give explicit prescriptions to calculate polarization induced bound interface charges for arbitrary x and barrier thicknesses up to 50 nm in each of the ternary III-N alloy heterostructures. In addition, we predict the electron sheet charges confined in heterostructures with positive polarization induced interface charges taking limitations for the epitaxial growth by strain and critical barrier thicknesses into account. Based on these results, we provide a detailed comparison of the sheet resistances and current-carrying capabilities of the heterostructures investigated, pointing to a superior potential of ScAlN/GaN based heterostructures for processing improved high electron mobility transistors for high-frequency and power electronic applications.
Direct writing of high-density nitrogen-vacancy centers inside diamond by femtosecond laser irradiation
Authors: Kurita Torataro , Shimotsuma Yasuhiko , Fujiwara Masanori , Fujie Masahiro , Mizuochi Norikazu , Shimizu Masahiro , Miura Kiyotaka
Published: May 2021

High-density nitrogen-vacancy (NV) centers exceeding 1016/cm3 inside a diamond can be achieved by femtosecond laser irradiation. The number of pulses and pulse energy were adjusted considering the increasing trend of the NV concentration and damage generation. The NV concentration first grew as the number of laser pulses was increased, and then the concentration was temporarily saturated or decreased. By increasing the number of laser pulses more than 2.5–5 × 107, the concentration increased again. The Hahn-echo measurement revealed that electron spins of the substitutional nitrogen center (P1) were dominant source for decoherence and the number of paramagnetic defects induced by the laser irradiation was not significant for degradation of spin coherence of the laser-induced NV centers even without a post-annealing process. Such high-dense ensemble NV centers are crucial for a high-sensitive quantum sensor.
Shear strength measurements and hydrostatic compression of rhenium diboride under high pressures
Authors: Burrage Kaleb C. , Park Changyong , Vohra Yogesh K.
Published: May 2021

Shear strength measurements have been carried out on rhenium diboride, ReB2, to a pressure of 74 GPa using a Radial X-ray Diffraction (R-XRD) technique in a diamond anvil cell using platinum as an internal x-ray pressure standard. The R-XRD result has provided a unique insight into the deformation of hexagonal crystal lattice under non-hydrostatic compression and variation of shear strength with increasing pressure. From R-XRD data, we have estimated hydrostatic component of compression to determine an equation of state of rhenium diboride yielding a bulk modulus of K0 = 366 ± 25 GPa with a pressure derivative K0′ = 4.3 ± 0.5 in good agreement with hydrostatic density functional theory calculations. The average lower bound of shear strength (τ) from various diffraction planes was then calculated using the measured interplanar d-spacing (dm) and hydrostatic component of d-spacing (dp) to be shown to approach 6.7 ± 0.4 GPa at 70 GPa. Our results show that the anisotropic compression effects observed in ReB2 under hydrostatic compression are correlated to electronic structure changes under compression as predicted by theoretical calculations.
Non-polar true-lateral GaN power diodes on foreign substrates
Authors: Wang Jia , Yu Guo , Zong Hua , Liao Yaqiang , Lu Weifang , Cai Wentao , Hu Xiaodong , Xie Ya-Hong , Amano Hiroshi
Published: May 2021

We have demonstrated non-polar GaN power diodes (Schottky barrier diode and p–n junction diode) on foreign substrates featuring the true-lateral p–n and metal–semiconductor junctions. The diodes were fabricated on GaN islands laterally overgrown on the mask-patterned sapphire and Si substrates by metalorganic vapor phase epitaxy. The anode and cathode were formed on the opposed a-plane sidewalls of the island, making the device architecture essentially like the 90° rotation of the desired true-vertical power diodes. The ideality factor of the Schottky barrier diode remained 1.0 (from 1.00 to 1.05) over 7 decades in current. Specifically, a high critical electric field of 3.3 MV/cm was demonstrated on the p–n junction diode with avalanche capability. These performances reveal a strong potential of non-polar GaN with the true-lateral junctions for high power applications.
Photoluminescence of ion-synthesized 9R-Si inclusions in SiO2/Si structure: Effect of irradiation dose and oxide film thickness
Authors: Nikolskaya Alena , Belov Alexey , Mikhaylov Alexey , Konakov Anton , Tetelbaum David , Korolev Dmitry
Published: May 2021

The study of hexagonal silicon polytypes attracts special attention due to their unique physical properties compared to the traditional cubic phase of Si. Thus, for some hexagonal phases, a significant improvement in the emission properties has been demonstrated. In this work, the luminescent properties of SiO2/Si structures irradiated with Kr+ ions at different doses and annealed at 800 °C have been systematically investigated. For such structures, a photoluminescence line at ∼ 1240 nm is observed and associated with the formation of hexagonal 9R-Si phase inclusions. It is found that the variation in the thickness of oxide film and the relative position of ion distribution profile and film/substrate interface leads to a regular change in the luminescence intensity. The nature of the observed dependencies is discussed as related mainly to the interplay between the factors contributing to the formation of 9R-Si inclusions and the generation of radiation defects in the Si substrate—centers of nonradiative recombination. The revealed regularities suggest optimal ion irradiation conditions for synthesis of optically active 9R-Si phase in diamond-like silicon.
Organic-component dependent thermal conductivity reduction in ALD/MLD grown ZnO:organic superlattice thin films
Authors: Ghiyasi Ramin , Milich Milena , Tomko John , Hopkins Patrick E. , Karppinen Maarit
Published: May 2021

Inorganic–organic superlattice (SL) thin films are intriguing candidates for flexible thermoelectric applications; in such SLs, the heat conduction can be efficiently blocked at the inorganic/organic interfaces. Fabrication of these materials using the atomic/molecular layer deposition (ALD/MLD) technique allows precise layer-sequence manipulation. Another unique advantage of ALD/MLD is its capability to yield conformal coatings even on demanding substrates such as textiles. These benefits have been demonstrated in previous works for SL thin films where ZnO serves as the inorganic matrix and hydroquinone as the organic component. In this work, we extend the study to three other organic components, i.e., p-phenylenediamine, terephthalic acid, and 4,4′-oxydianiline, to address the importance of the bonding structure and the density difference at the inorganic/organic interface, and the thickness of the monomolecular organic blocking layer.
MiR-124 synergism with ELAVL3 enhances target gene expression to promote neuronal maturity
Authors: Lu Ya-Lin , Liu Yangjian , McCoy Matthew J. , Yoo Andrew S.
Published: May 2021

Significance

MicroRNAs (miRNAs) are small noncoding RNAs that when loaded into Argonuate (AGO) form the RNA-induced silencing complex that represses target transcripts. Here, in addition to the canonical repressive miRNA function, we identified the activity of miR-124, a neuron-enriched miRNA, as a positive regulator of its target genes. Transcripts harboring both miR-124 and ELAVL3, an RNA-binding protein, target sites at the 3′ untranslated region (3′UTR) allowing for the synergism of AGO-miR124 and ELAVL3 to enhance its target gene expression. The switch of miR-124 as a positive regulator is essential for facilitating neuronal reprogramming of human fibroblasts and promoting the functional maturity of primary human neurons. Our study provides a conceptual advance in microRNA’s function in regulating neuronal identity and function.
Contractility, focal adhesion orientation, and stress fiber orientation drive cancer cell polarity and migration along wavy ECM substrates
Authors: Fischer Robert S. , Sun Xiaoyu , Baird Michelle A. , Hourwitz Matt J. , Seo Bo Ri , Pasapera Ana M. , Mehta Shalin B. , Losert Wolfgang , Fischbach Claudia , Fourkas John T. , Waterman Clare M.
Published: May 2021

Significance

Tumor progression to enable metastasis includes remodeling the wavy bundles of collagen making up the tissue stromal extracellular matrix (ECM) into straight bundles within the tumor microenvironment. While wavy collagen bundles are thought to be inhibitory to cell polarization and migration in tissue, straight ECM fibers are thought to be conducive, thereby mediating metastasis. We used nanofabricated cell culture substrates that mimic the ECM fiber waveforms seen in both benign- and metastases-promoting tumor ECMs. Large amplitude ECM waves depolarized tumor cells and decreased directional migration via cell contractility-mediated organization of the cytoskeleton and adhesions. Thus, ECM architecture of normal tissue and benign tumors may generally inhibit tumor cell exit, but this may be overcome by increasing tumor cell contractility.
Spatial variation in the joint effect of extreme heat events and ozone on respiratory hospitalizations in California
Authors: Schwarz Lara , Hansen Kristen , Alari Anna , Ilango Sindana D. , Bernal Nelson , Basu Rupa , Gershunov Alexander , Benmarhnia Tarik
Published: May 2021

Significance

Projections show that extreme heat events and high ozone days are expected to increase under climate change. Both exposures are harmful to human health, but warning systems, typically implemented separately, do not consider the joint effects of these exposures. In this study, we propose a method to address spatial differences of the joint effects of extreme heat events and ozone peaks on respiratory hospitalizations at the zip code level in California. Zip codes with low median income and high unemployment rates are at increased risk for these joint effects. Results identified zip codes with increased vulnerability, demonstrating the importance of going beyond average measures to prioritize areas for joint warning systems and protect population health.
Wolves make roadways safer, generating large economic returns to predator conservation
Authors: Raynor Jennifer L. , Grainger Corbett A. , Parker Dominic P.
Published: May 2021

Significance

Measuring the economic benefits conveyed by predators is difficult—often, effects are indirect and operate through complex ecological changes. As a result, debates about the expansion of predators have pit salient costs against more speculative estimates of benefits that might be dismissed as unreliable or ideologically motivated. We quantify the indirect benefits of wolves (Canis lupus) to human lives and property through reductions in deer-vehicle collisions. Moreover, we decompose the effect into two components: changes in prey behavior versus prey abundance. This decomposition is important when effective policy depends on whether hunters can replicate the effects of predators. In the case of wolves, we conclude that human deer hunters cannot.
Bright daytime light enhances circadian amplitude in a diurnal mammal
Authors: Bano-Otalora Beatriz , Martial Franck , Harding Court , Bechtold David A. , Allen Annette E. , Brown Timothy M. , Belle Mino D. C. , Lucas Robert J.
Published: May 2021

Significance

Light is an important regulator of endogenous circadian clocks. Regular light–dark cycles set circadian phase to ensure synchrony with external time, while irregular or inappropriate light exposure can disrupt circadian rhythms. We ask here whether light can also impact another key parameter of circadian rhythms, their amplitude, under conditions of stable entrainment. Using a diurnal rodent species and carefully calibrated light stimuli, we show that increasing the intensity of daytime light enhances the reproducibility and robustness of behavioral and physiological rhythms and increases the amplitude of circadian rhythms in electrical activity in the central brain pacemaker. These findings reveal an impact of light on circadian amplitude and highlight the potential importance of daytime light exposure for circadian health.
A chromosome-level genome of a Kordofan melon illuminates the origin of domesticated watermelons
Authors: Renner Susanne S. , Wu Shan , Pérez-Escobar Oscar A. , Silber Martina V. , Fei Zhangjun , Chomicki Guillaume
Published: May 2021

Significance

Wild progenitors of crops are important resources for breeding and for understanding domestication, but identifying them is difficult. Using an integrative approach, we discovered that a Sudanese form of melon with nonbitter whitish pulp, known as the Kordofan melon, is the closest relative of domesticated watermelons and a possible progenitor. To gain insights into the genetic changes that occurred from the progenitor to the domesticated watermelon, we assembled and annotated the genome of a Kordofan melon at the chromosome level. Our analyses imply that early farmers brought into cultivation already nonbitter watermelons, different from other domesticated Cucurbitaceae crops such as cucumber. The Kordofan melon genome is a significant new resource for watermelon breeding.
Thyroid hormones regulate the formation and environmental plasticity of white bars in clownfishes
Authors: Salis Pauline , Roux Natacha , Huang Delai , Marcionetti Anna , Mouginot Pierick , Reynaud Mathieu , Salles Océane , Salamin Nicolas , Pujol Benoit , Parichy David M. , Planes Serge , Laudet Vincent
Published: May 2021

Significance

Developmental plasticity is defined as the ability of an organism to adjust its development depending on environmental signals, thus producing alternative phenotypes precisely adjusted to the environment. Yet, the mechanisms underlying developmental plasticity are not fully understood. We found that juvenile clownfish delay the development of their white bars during metamorphosis depending on the sea anemone species in which they are recruited. To understand this developmental plasticity, we investigated roles for thyroid hormones, the main hormones triggering metamorphosis in vertebrates. We found that thyroid hormones regulate white bar formation and that a shift in hormone levels, associated with ecological differences, results in divergent color patterns in different sea anemone species in which the young fish is recruited.
Zika virus employs the host antiviral RNase L protein to support replication factory assembly
Authors: Whelan Jillian N. , Parenti Nicholas A. , Hatterschide Joshua , Renner David M. , Li Yize , Reyes Hanako M. , Dong Beihua , Perez Erick R. , Silverman Robert H. , Weiss Susan R.
Published: May 2021

Significance

Since 2015, Zika virus (ZIKV) has been recognized as a serious public health concern due to devastating birth defects caused by ZIKV infection of pregnant women. An improved understanding of ZIKV employment of host factors to facilitate infection would enhance our knowledge of the subcellular events driving severe clinical outcomes of ZIKV infection and provide potential avenues for therapeutic and vaccine development to combat this virus. We reveal that ZIKV exploits the host RNase L protein to assist in generation of new virus, a feature that is not shared during infection with other flaviviruses, thus identifying a unique host interaction possibly facilitating ZIKV pathogenesis.
Aging as a consequence of selection to reduce the environmental risk of dying
Authors: Omholt Stig W. , Kirkwood Thomas B. L.
Published: May 2021

Significance

A fresh perspective on the evolution of aging is developed, which focuses on optimizing an individual’s exposure to mortality risk across the life course. A significant source of risk is associated with the act of acquiring the energy necessary for all functions of life. In particular, a considerable fraction of lifetime energy acquisition is used for somatic maintenance. We show how reduction of mortality risk through restrained allocation to somatic maintenance may enhance lifetime fitness but result in aging. Our results are discussed in relation to current theories of the evolution of aging, where we anticipate it will help to illuminate the debate about the mechanisms underlying aging in the wild and the nature and roles of trade-offs.
PilB from
Streptococcus sanguinis
is a bimodular type IV pilin with a direct role in adhesion
Authors: Raynaud Claire , Sheppard Devon , Berry Jamie-Lee , Gurung Ishwori , Pelicic Vladimir
Published: May 2021

Significance

Type IV pili (T4P) are functionally versatile filaments widespread in prokaryotes, composed of type IV pilins and assembled by conserved multiprotein machineries. It remains unclear how such rather simple filaments can be so versatile. Our structure/function analysis of PilB, a minor pilin of
Streptococcus sanguinis
T4P, offers an elegant explanation for this paradox. We show that PilB is a modular pilin with a bulky module “grafted” onto a small pilin module, which directly mediates adhesion of
S. sanguinis
to host cells/proteins. This evolutionary tinkering strategy appears to be prevalent in bacteria since a global analysis reveals that modular pilins are widespread and exhibit an astonishing variety of architectures.
Exploring J/ψ Production Mechanism at the Future Electron-Ion Collider
Authors: Qiu Jian-Wei , Wang Xiang-Peng , Xing Hongxi
Published: May 2021

We propose to use transverse momentum p
T distribution of J/ψ production at the future Electron Ion Collider (EIC) to explore the production mechanism of heavy quarkonia in high energy collisions. We apply QCD and QED collinear factorization to the production of a

c

c
¯

pair at high p
T, and non-relativistic QCD factorization to the hadronization of the pair to a J/ψ. We evaluate J/ψ
p
T-distribution at both leading and next-to-leading order in strong coupling, and show that production rates for various color-spin channels of a

c

c
¯

pair in electron-hadron collisions are very different from that in hadron-hadron collisions, which provides a strong discriminative power to determine various transition rates for the pair to become a J/ψ. We predict that the J/ψ produced in electron-hadron collisions is likely unpolarized, and the production is an ideal probe for gluon distribution of colliding hadron (or nucleus). We find that the J/ψ production is dominated by the color-octet channel, providing an excellent probe to explore the gluon medium in large nuclei at the EIC.
Configuration Interaction of Electronic Structure and Spectroscopy of AlH and Its Cation
*
Authors: Zhao Shu-Tao , Li Jun , Li Rui , Yin Shuang , Guo Hui-Jie
Published: May 2021

We carry out a detailed study of the low-lying states of AlH and AlH+, using a multireference configuration interaction method. Based on the computed potential energy curves, the spectroscopic constants of bound Λ–S states are fitted; these agree with the results for the measurements. The values of the permanent dipole moment of the Λ–S states are calculated, and the charge transfer mechanism is discussed. Based on the calculated transition dipole moments and vibrational levels, the radiative lifetimes of bound states are determined. Finally, tunneling lifetimes, and ν′ = 0–2 vibrational levels of 42
Σ
+ and 32
Π states with a potential barrier are investigated.
Strong-Field-Induced

N2+

Air Lasing in Nitrogen Glow Discharge Plasma
Authors: Dong Nana , Zhou Yan , Pang Shanbiao , Huang Xiaodong , Liu Ke , Deng Lunhua , Xu Huailiang
Published: May 2021

We investigate

N
2
+

air lasing at 391 nm, induced by strong laser fields in a nitrogen glow discharge plasma. We generate forward

N
2
+

air lasing on the

B
2

Σ
u
+

(

v
′

=
0
)

–

X
2

Σ
g
+

(

v
″

=
0
)

transition at 391 nm by irradiating an intense 35-fs, 800-nm laser in a pure nitrogen gas, finding that the 391-nm lasing quenches when the nitrogen gas is electrically discharged. In contrast, the 391-nm fluorescence measured from the side of the laser beam is strongly enhanced, demonstrating that this discharge promotes the population in the

B
2

Σ
u
+

(

v
′

=
0
)

state. By comparing the lasing and fluorescence spectra of the nitrogen gas obtained in the discharged and laser-induced plasma, we show that the quenching of

N
2
+

lasing is caused by the efficient suppression of population inversion between the

B
2

Σ
u
+

and

X
2

Σ
g
+

states of

N
2
+

, in which a much higher population occurs in the

X
2

Σ
g
+

state in the discharge plasma. Our results clarify the important role of population inversion in generating

N
2
+

air lasing, and also indicate the potential for the enhancement of

N
2
+

lasing via further manipulation of the population in the

X
2

Σ
g
+

state in the discharged medium.
A Noise-Robust Pulse for Excitation Transfer in a Multi-Mode Quantum Memory
Authors: Gong Bo , Tu Tao , Guo Ao-Lin , Zhu Le-Tian , Li Chuan-Feng
Published: May 2021

Multi-mode quantum memory is a basic element required for long-distance quantum communication, as well as scalable quantum computation. For on-demand readout and long storage times, control pulses are crucial in order to transfer atomic excitations back and forth into spin excitations. Here, we introduce noise-robust composite pulse sequences for high-fidelity excitation transfer in multi-mode quantum memory. These pulses are robust to the deviations in amplitude and the detuning parameters of realistic conditions. We show the efficiency of these composite pulses with a typical rare-earth ion-doped system. This approach could be applied to a variety of quantum memory schemes.
Approach to Phonon Relaxation Time and Mean Free Path in Nonlinear Lattices
Authors: Liu Yue , He Dahai
Published: May 2021

Based on the self-consistent phonon theory, the spectral energy density is calculated by the canonical transformation and the Fourier transformation. Through fitting the spectral energy density by the Lorentzian profile, the phonon frequency as well as the phonon relaxation time is obtained in one-dimensional nonlinear lattices, which is validated in the Fermi–Pasta–Ulam-β (FPU-β) and ϕ
4 lattices at different temperatures. The phonon mean free path is then evaluated in terms of the phonon relaxation time and phonon group velocity. The results show that, in the FPU-β lattice, the phonon mean free path as well as the phonon relaxation time displays divergent power-law behavior. The divergent exponent coincides well with that derived from the Peierls–Boltzmann theory at weak anharmonic nonlinearity. The value of the divergent exponent expects a power-law divergent heat conductivity with system size, which violates Fourier’s law. For the ϕ
4 lattice, both the phonon relaxation time and mean free path are finite, which ensures normal heat conduction.
Nonlinear Simulations of the Bump-on-Tail Instabilities in Tokamak Plasmas
Authors: Hou Yumei , Chen Wei , Yu Liming , Zou Yunpeng , Xu Min , Duan Xuru
Published: May 2021

We reproduce nonlinear behaviors, including frequency chirping and mode splitting, referred to as bump-on-tail instabilities. As has been reported in previous works, the generation and motion of phase-space hole-clump pairs in a kinetically driven, dissipative system can result in frequency chirping. We provide examples of frequency chirping, both with and without pure diffusion, in order to illustrate the role of the diffusion effect, which can suppress holes and clumps; Asymmetric frequency chirpings are produced with drag effect, which is essential to enhance holes, and suppress clumps. Although both diffusion and drag effect suppress the clumps, downward sweepings are observed, caused by a complicated interaction of diffusion and drag. In addition, we examine the discrepancies in frequency chirping between marginally unstable, and far from marginally unstable cases, which we elucidate by means of a dissipative system. In addition, mode splitting is also produced via BOT code for a marginal case with large diffusion.
Coriolis Force Effect on Suppression of Neo-Classical Tearing Mode Triggered Explosive Burst in Reversed Magnetic Shear Tokamak Plasmas
Authors: Liu Tong , Wei Lai , Wang Feng , Wang Zheng-Xiong
Published: May 2021

We numerically investigate the Coriolis force effect on the suppression of an explosive burst, triggered by the neo-classical tearing mode, in reversed magnetic shear configuration tokamak plasmas, using a reduced magnetohydrodynamic model, including bootstrap current. Previous works have shown that applying differential poloidal rotation, with rotation shear located near the outer rational surface, is an effective way to suppress an explosive burst. In comparison with cases where there is no Coriolis force, the amplitude of differential poloidal rotation required to effectively suppress the explosive burst is clearly reduced once the effect of Coriolis force is taken into consideration. Moreover, the effective radial region of the rotation shear location is broadened in cases where the Coriolis force effect is present. Applying rotation with shear located between the radial positions of q
min and the outer rational surface always serves to effectively suppress explosive bursts, which we anticipate will reduce operational difficulties in controlling explosive bursts, and will consequently prevent plasma disruption in tokamak experiments.
Superior Mechanical Properties of GaAs Driven by Lattice Nanotwinning
Authors: Han Zhenjiang , Liu Han , Li Quan , Zhou Dan , Lv Jian
Published: May 2021

Gallium arsenide (GaAs), a typical covalent semiconductor, is widely used in the electronic industry, owing to its superior electron transport properties. However, its brittle nature is a drawback that has so far significantly limited its application. An exploration of the structural deformation modes of GaAs under large strain at the atomic level, and the formulation of strategies to enhance its mechanical properties is highly desirable. The stress-strain relations and deformation modes of single-crystal and nanotwinned GaAs under various loading conditions are systematically investigated, using first-principles calculations. Our results show that the ideal strengths of nanotwinned GaAs are 14% and 15% higher than that of single-crystal GaAs under pure and indentation shear strains, respectively, without producing a significantly negative effect in terms of its electronic performance. The enhancement in strength stems from the rearrangement of directional covalent bonds at the twin boundary. Our results offer a fundamental understanding of the mechanical properties of single crystal GaAs, and provide insights into the strengthening mechanism of nanotwinned GaAs, which could prove highly beneficial in terms of developing reliable electronic devices.
Non-Monotonic Evolution of Carrier Density and Mobility under Thermal Cycling Treatments in Dirac Semimetal Cd3As2 Microbelts
Authors: Chen Zheng , Wu Min , Liu Yequn , Gao Wenshuai , Han Yuyan , Zhou Jianhui , Ning Wei , Tian Mingliang
Published: May 2021

Tunable carrier density plays a key role in the investigation of novel transport properties in three-dimensional topological semimetals. We demonstrate that the carrier density, as well as the mobility, of Dirac semimetal Cd3As2 nanoplates can be effectively tuned via in situ thermal treatment at 350 K for one hour, resulting in non-monotonic evolution by virtue of the thermal cycling treatments. The upward shift of Fermi level relative to the Dirac nodes blurs the surface Fermi-arc states, accompanied by an anomalous phase shift in the oscillations of bulk states, due to a change in the topology of the electrons. Meanwhile, the oscillation peaks of bulk longitudinal magnetoresistivity shift at high fields, due to their coupling to the oscillations of the surface Fermi-arc states. Our work provides a thermal control mechanism for the manipulation of quantum states in Dirac semimetal Cd3As2 at high temperatures, via their carrier density.
Emergence of Chern Insulating States in Non-Magic Angle Twisted Bilayer Graphene
Authors: Shen Cheng , Ying Jianghua , Liu Le , Liu Jianpeng , Li Na , Wang Shuopei , Tang Jian , Zhao Yanchong , Chu Yanbang , Watanabe Kenji , Taniguchi Takashi , Yang Rong , Shi Dongxia , Qu Fanming , Lu Li , Yang Wei , Zhang Guangyu
Published: May 2021

Twisting two layers into a magic angle (MA) of ∼1.1° is found essential to create low energy flat bands and the resulting correlated insulating, superconducting, and magnetic phases in twisted bilayer graphene (TBG). While most of previous works focus on revealing these emergent states in MA-TBG, a study of the twist angle dependence, which helps to map an evolution of these phases, is yet less explored. Here, we report a magneto-transport study on one non-magic angle TBG device, whose twist angle θ changes from 1.25° at one end to 1.43° at the other. For θ = 1.25° we observe an emergence of topological insulating states at hole side with a sequence of Chern number | C | = 4 – | v |, where v is the number of electrons (holes) in moiré unite cell. When θ > 1.25°, the Chern insulator from flat band disappears and evolves into fractal Hofstadter butterfly quantum Hall insulator where magnetic flux in one moiré unite cell matters. Our observations will stimulate further theoretical and experimental investigations on the relationship between electron interactions and non-trivial band topology.
Combined Study of Structural, Magnetic and Transport Properties of Eu0.5
Ln
0.5BiS2F Superconductor*
Authors: Zhai Hui-Fei , Lin Bo , Zhang Pan , Jiang Hao , Li Yu-Ke , Cao Guang-Han
Published: May 2021

Superconductivity below 0.3 K and a charge-density-wave-like (CDW-like) anomaly at 280 K were observed in EuBiS2F recently. Here we report a systematic study of structural and transport properties in Eu0.5Ln0.5BiS2F (Ln = La, Ce, Pr, Nd, Sm) by electrical resistivity, magnetization, and specific heat measurements. The lattice constants have a significant change upon rare earth substitution for Eu, suggesting an effective doping. As Ln is changed from Sm to La, the superconducting transition temperature T
c increases from 1.55 K to 2.8 K. In contrast to the metallic parent compound, the temperature dependence of electrical resistivity displays semiconducting-like behavior for all the Eu0.5
Ln
0.5BiS2F samples. Meanwhile, the CDW-like anomaly observed in EuBiS2F is completely suppressed. Unlike the mixed valence state in the undoped compound, Eu ions in these rare-earth-doped samples are mainly divalent. A specific anomaly at 1.3 K resembling that in EuBiS2F suggests the coexistence of superconductivity and spin glass state for Eu0.5La0.5BiS2F. Coexistence of ferromagnetic order and superconductivity is found below 2.2 K in Eu0.5Ce0.5BiS2F samples. Our results supplies a rich diagram showing that many interesting properties can be induced in BiS2-based compounds.
Spin-Wave Dynamics in an Artificial Kagome Spin Ice
Authors: Li Qiuyang , Xiong Suqin , Chen Lina , Zhou Kaiyuan , Xiang Rongxin , Li Haotian , Gao Zhenyu , Liu Ronghua , Du Youwei
Published: May 2021

Artificial spin ice (ASI) structures have significant technological potential as reconfigurable metamaterials and magnetic storage media. We investigate the field/frequency-dependent magnetic dynamics of a kagome ASI made of 25-nm-thick permalloy nanomagnet elements, combining magnetoresistance (MR) and microscale ferromagnetic resonance (FMR) techniques. Our FMR spectra show a broadband absorption spectrum from 0.2 GHz to 3 GHz at H below 0.3 kOe, where the magnetic configuration of the kagome ASI is in the multidomain state, because the external magnetic field is below the obtained coercive field H
c ∼ 0.3 kOe, based on both the low-field range MR loops and simulations, suggesting that the low-field magnetization dynamics of kagome ASI is dominated by a multimode resonance regime. However, the FMR spectra exhibit five distinctive resonance modes at the high-field quasi-uniform magnetization state. Furthermore, our micromagnetic simulations provide additional spatial resolution of these resonance modes, identifying the presence of two high-frequency primary modes, localized in the horizontal and vertical bars of the ASI, respectively; three other low-frequency modes are mutually exclusive and separately pinned at the corners of the kagome ASI by an edge-induced dipolar field. Our results suggest that an ASI structural design can be adopted as an efficient approach for the development of low-power filters and magnonic devices.
Rare-Earth Chalcohalides: A Family of van der Waals Layered Kitaev Spin Liquid Candidates
Authors: Ji Jianting , Sun Mengjie , Cai Yanzhen , Wang Yimeng , Sun Yingqi , Ren Wei , Zhang Zheng , Jin Feng , Zhang Qingming
Published: May 2021

The Kitaev spin liquid (KSL) system has attracted tremendous attention in recent years because of its fundamental significance in condensed matter physics and promising applications in fault-tolerant topological quantum computation. Material realization of such a system remains a major challenge in the field due to the unusual configuration of anisotropic spin interactions, though great effort has been made before. Here we reveal that rare-earth chalcohalides REChX (RE = rare earth; Ch = O, S, Se, Te; X = F, Cl, Br, I) can serve as a family of KSL candidates. Most family members have the typical SmSI-type structure with a high symmetry of

R

3
¯

m

, and rare-earth magnetic ions form an undistorted honeycomb lattice. The strong spin-orbit coupling of 4f electrons intrinsically offers anisotropic spin interactions as required by the Kitaev model. We have grown the crystals of YbOCl and synthesized the polycrystals of SmSI, ErOF, HoOF and DyOF, and made careful structural characterizations. We carry out magnetic and heat capacity measurements down to 1.8 K and find no obvious magnetic transition in all the samples but DyOF. The van der Waals interlayer coupling highlights the true two-dimensionality of the family which is vital for the exact realization of Abelian/non-Abelian anyons, and the graphene-like feature will be a prominent advantage for developing miniaturized devices. The family is expected to act as an inspiring material platform for the exploration of KSL physics.