bluuebunny/crossref_metadata_2025 huggingface dataset:
Reducibility of Schrödinger equation at high frequencies
Authors: Sun Yingte
Published: June 2020

In this paper, we prove a reducibility result for a linear Schrödinger equation with a time quasi-periodic perturbation on T. In contrast with previous reducibility results of the Schrödinger equation, the assumption of the small amplitude of the time quasi-periodic perturbation is replaced by fast oscillating.
Integration of fluorographene trapping medium in MoS2-based nonvolatile memory device
Authors: Chang Kai Ping , Abushammala Haneen , Sahoo Mamina , Jaffre Alexandre , Alamarguy David , Jiang Yu , Boutchich Mohamed , Lai Chao-Sung
Published: June 2020

Graphene and 2D analogs such as transition metal dichalcogenides (TMDCs) have been widely investigated for their tuneable electronic properties. There is a large spectrum of applications of such 2D analogs; for example, non-volatile memory, which is a key building block for future low-power consumer electronics. In this work, we have investigated a vertical heterostructure composed of a chemical vapour-deposited molybdenum disulphide transistor channel coupled with silicon tunnel oxide (SiO2) and hafnium oxide as a blocking barrier, with fluorographene (FGr) being used as the charge trapping medium. Owing to the larger trap density of FGr, the memory window is three times larger, and the data retention measurements at room temperature yield a 50% charge loss extrapolated to 10 years. The low barrier at the FGr/SiO2 interface induces a steeper charge loss for holes. Nevertheless, the stack can sustain at least to 550 cycles without showing any sign of degradation. Although bandgap engineering is required to improve the data retention, particularly for the holes, the combination studied here is an encouraging route for 2D-based non-volatile memories.
Ultrafast x-ray and electron scattering of free molecules: A comparative evaluation
Authors: Ma Lingyu , Yong Haiwang , Geiser Joseph D. , Moreno Carrascosa Andrés , Goff Nathan , Weber Peter M.
Published: June 2020

Resolving gas phase molecular motions with simultaneous spatial and temporal resolution is rapidly coming within the reach of x-ray Free Electron Lasers (XFELs) and Mega-electron-Volt (MeV) electron beams. These two methods enable scattering experiments that have yielded fascinating new results, and while both are important methods for determining transient molecular structures in photochemical reactions, it is important to understand their relative merits. In the present study, we evaluate the respective scattering cross sections of the two methods and simulate their ability to determine excited state molecular structures in light of currently existing XFEL and MeV source parameters. Using the example of optically excited N-methyl morpholine and simulating the scattering patterns with shot noise, we find that the currently achievable signals are superior with x-ray scattering for equal samples and on a per-shot basis and that x-ray scattering requires fewer detected signal counts for an equal fidelity structure determination. Importantly, within the independent atom model, excellent structure determinations can be achieved for scattering vectors only to about 5 Å−1, leaving larger scattering vector ranges for investigating vibrational motions and wavepackets. Electron scattering has a comparatively higher sensitivity toward hydrogen atoms, which may point to applications where electron scattering is inherently the preferred choice, provided that excellent signals can be achieved at large scattering angles that are currently difficult to access.
Population congestion in 3-state quantum-dot cellular automata
Authors: Retallick Jacob , Walus Konrad
Published: June 2020

The behavior of quantum-dot cellular automata (QCA) networks is typically understood through considering polarization-like interactions with energies arising from the agreement or disagreement of the defined polarization states of neighboring QCA devices. It is known that additional interactions are present in 3-state molecular QCA that alter the required clocking fields needed for a device operation. Recent efforts in implementing logic gates using patterned dangling bonds (SiDBs) on hydrogen passivated silicon reveal significant challenges arising from similar effects. The necessary applied electrical potential needed to increase the population of an SiDB is strongly dependent on the current population of its neighbors, an effect we term congestion. It is unclear whether the strength of these interactions may pose an obstacle for future applications of SiDBs as a nanoscale QCA architecture. In this work, we investigate 3-state QCA in the regime in which congestion is significant and determine the extent to which such effects can be mitigated for SiDB devices. We propose that while SiDB-based QCA wires may be achievable depending on limitations of inter-dot tunneling, higher density devices such as majority gates may need to be replaced by more architecture specific implementations unless net-neutral variants of SiDB QCA devices can be demonstrated.
Control of defect formation and ordering in Eu3+ doped RE2Ce2O7 (RE = La, Y, and Gd) red phosphor
Authors: Raj Athira K. V. , Prabhakar Rao P. , Sreena T. S.
Published: June 2020

The control of defect formation and ordering in the lattice on the photoluminescence properties of Eu3+ doped RE2Ce2O7 is studied by the incorporation of some rare earth elements (RE = Y, La, Gd) in the system. Structural studies divulge all the compositions to crystallize into a fluorite type structure with the space group Fm3m. Raman mode analysis supplements the confirmation of the fluorite structure and further indicates an oxygen vacancy ordering in the lattice from Y to Gd. The defect formation of Ce3+ concentration from the x-ray photoelectron spectroscopy analysis shows dependence on the type of rare earths. The ordering in the lattice is associated more with the trapping/repelling of oxygen vacancy based on the rare earth. In other words, the defect formation is minimum for Gd by trapping more oxygen vacancies and maximum for the Y system due to more disorders in the lattice. The Ce3+ concentration and the ordering greatly affected the absorbance and luminescence properties. Thus, the Gd system with more ordering and less defect formation exhibited enhanced red emission of Eu3+ (612 nm), which is more than 1.8 times that of La based phosphors and 11 times better than Ce0.9O2:0.1Eu3+. Also, studies on the effect of Eu3+ concentration in the Gd2−xCe2O7:xEu3+ system indicated further improvements in the red emission intensity along with a high asymmetric ratio, good chromaticity coordinates (0.66, 0.35), and high color purity (97.6%). This study demonstrates that the role of ordering associated with defect formation plays significantly in determining the luminescence properties.
Dynamic acoustic tractor beams II: Oscillatory powers, cross sections, and energy efficiencies of a spherical non-viscous liquid droplet
Authors: Mitri F. G.
Published: June 2020

A previous work on dynamic acoustic tractor beams [Mitri, J. Appl. Phys. 117, 094903 (2015)] demonstrated the feasibility of pulling a liquid sphere toward a finite circular piezo-disk transducer and vibrating it around an equilibrium position at the beat frequency of two interfering waves driven at slightly different frequencies. The analysis is extended here to investigate the oscillatory phenomenon from the standpoint of energy conservation applied to scattering. Expressions for dynamic scattering, extinction and absorption powers, and their related cross sections and energy efficiencies are formally defined and derived based on the partial-wave series expansion method in spherical coordinates and the short-term time averaging (STTA) procedure. A circular flat piston transducer insonifying a spherical liquid hexane droplet (with arbitrary radius) centered on the axis of wave propagation is considered. Numerical predictions for dynamic extinction and scattering energy efficiencies illustrate the theory. A percentage error criterion related to extinction and scattering energy efficiencies is defined. Computations are also performed to quantify the numerical inaccuracy introduced by the difference-frequency component of the STTA. This criterion must be always utilized as a benchmark tool to validate dynamic radiation force computations. The results show that the percent error (induced by the difference-frequency component of the STTA process) increases as the dimensionless difference-frequency Δka increases. The present analysis is of some importance to validate dynamic radiation force numerical computations from the standpoint of energy conservation, used in the design and optimization of dynamic/oscillatory acoustic tractor beams and single-beam tweezers.
Impact of helium neutral gas puff on plasma turbulence in linear magnetized argon plasmas
Authors: Kobayashi T. , Kin F. , Kawachi Y. , Sasaki M. , Kosuga Y. , Yamasaki K. , Inagaki S.
Published: June 2020

In order to explore the impact of the neutrals on the plasma turbulence, a new gas puff system is developed for a linear magnetized plasma column PANTA. Helium gas is injected into the argon plasma without changing the electron density profile. After the helium gas puff, the dominant fluctuation mode changes from the broadband m = 2 drift wave to the coherent m = 1 mode, where m is the azimuthal mode number. Accordingly, the property of the nonlinear coupling with other fluctuating modes changes from broadband couplings to coherent couplings.
Diamagnetic coupling for magnetic tuning in nano-thin films
Authors: Vopson M. M. , Belusky M. , Lepadatu S.
Published: June 2020

Combining nanoscale thin films of magnetic and non-magnetic phases in various hetero-structures has generated a rich variety of new magnetic and magneto-transport phenomena and applications. Here, we propose a coupling between ferromagnetic and diamagnetic layers. We used this diamagnetic coupling to improve the exchange bias field of a diamagnet/ferromagnet/anti-ferromagnet hetero-structure by up to 212%, as evidenced in the experiments presented here. Since diamagnets have very special properties, including temperature independent negative magnetic susceptibilities, this coupling could be a powerful tool in future synthesis of solid state nanostructures such as exchange bias systems, spintronic devices, magnetic random access memories, sensors, and multiferroics.
Differentiation of non-volatile strain and ferroelectric field effects in (011)- and (001)-La0.67Sr0.33MnO3/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 heterostructures
Authors: Wang P. , Jin C. , Wang Y. C. , Liu S. S. , Wang X. Y. , Zheng D. X. , Zheng W. C. , Bai H. L.
Published: June 2020

La0.67Sr0.33MnO3 (LSMO) thin films were fabricated on (011)- and (001)-Pb(Mg1/3Nb2/3)1 − xTixO3 (PMN-PT) substrates to investigate the mechanism of electric field regulation. Both (011)- and (001)-LSMO/PMN-PT heterostructures exhibit electric-field-dependent resistance curves with an asymmetric butterfly shape under a bipolar electric field (±10 kV/cm). Confirmed through a mathematical method, the “butterfly” and “asymmetric” characteristics indicate the volatile strain and non-volatile ferroelectric field effects, respectively. However, by applying a unipolar electric field, the electric-field-dependent resistance curves of the (011)-LSMO/PMN-PT heterostructures present a larger loop shape than those in the (001)-LSMO/PMN-PT heterostructure, which is related to the non-volatile strain effect. The volatile strain, non-volatile strain, and ferroelectric field effects on the resistance of the LSMO films are associated with the enhanced or weakened double exchange coupling.
Long-wave infrared scattering spectra and modeling of trace particles on surfaces for standoff detection
Authors: Martinez Ramon A. , Guo Kaiwen , Terry Fred L. , Zhai Tianqu , Islam Mohammed N. , Ifarraguerri Agustin I.
Published: June 2020

We experimentally measure the scattered reflectance of particles deposited on smooth substrates with a mid-wave to long-wave supercontinuum source and a FTIR based sensor at 3.6 m. We measure the scattering return from sparse particles of 1,3,5-Trinitroperhydro-1,3,5-triazine, caffeine, and acetaminophen deposited on smooth aluminum, silicon, and glass substrates. We also measure mono-disperse 5.4, 10.8, and 19.4 μm diameter polystyrene spheres deposited on aluminum. We demonstrate that spectra obtained using our supercontinuum FTIR sensor can be accurately simulated using a Bobbert–Vlieger model, and non-spherical particle spectra can be approximated by spherical results. The Bobbert–Vlieger model can then be used to create a library that can account for the trace chemical and underlying substrate for standoff chemical identification.
Gated Hall and field-effect transport characterization of e-mode ZnO TFTs
Authors: Anders J. , Kazimierczuk M. , Leedy K. , Miller N. , Cooper T. , Streby M. , Schuette M.
Published: June 2020

Two methods of measuring the electronic transport properties of a material are transistor DC-voltage and the Hall effect. Hall mobility measurements of normally off semiconductors can be done by electrostatic doping to lower resistance in the channel. We show that by measuring both, we can compare any value (raw measured as well as calculated data) directly to any other value along an index of FET gate and drain voltage across the entire safe operating area of the device. Our gated Hall technique intrinsic calculations of Hall mobility, typically possible only for bulk or doped materials, for thin-film transistor materials stack up with thickness scaled to practical values.
Squeezed light induced two-photon absorption fluorescence of fluorescein biomarkers
Authors: Li Tian , Li Fu , Altuzarra Charles , Classen Anton , Agarwal Girish S.
Published: June 2020

Two-photon absorption (TPA) fluorescence of biomarkers has been decisive in advancing the fields of biosensing and deep-tissue in vivo imaging of live specimens. However, due to the extremely small TPA cross section and the quadratic dependence on the input photon flux, extremely high peak-intensity pulsed lasers are imperative, which can result in significant photo- and thermal damage. Previous works on entangled TPA with spontaneous parametric downconversion light sources found a linear dependence on the input photon-pair flux, but are limited by low optical powers, along with a very broad spectrum. We report that by using a high-flux squeezed light source for TPA, a fluorescence enhancement of ∼47 is achieved in fluorescein biomarkers as compared to classical TPA. Moreover, a polynomial behavior of the TPA rate is observed in the the laser dye 4-dicyanomethylene-2-methyl-6-(p(dimethylamino)styryl)-4H-pyran in dimethyl sulphoxide.
Highly efficient wurtzite/zinc blende CdS visible light photocatalyst with high charge separation efficiency and stability
Authors: Zhu Jingxian , Jiang Wenshuai , Wang Bin , Niu Lijuan , Dong Chenxi , Qu Dan , An Li , Wang Xiayan , Sun Zaicheng
Published: June 2020

Mixed phase TiO2 (Degussa P25) exhibits superior photocatalytic performance and stability due to the formation of the hetero-phase junction between anatase and rutile. However, the large bandgap limits its visible light activity. CdS is a photocatalyst with a broad light absorption band up to 550 nm. Constructing a hetero-phase junction will greatly promote the photocatalytic activity of CdS. In this work, the one-step solvothermal method was used to synthesize CdS hetero-phase junction with both hexagonal wurtzite (WZ) and cubic zinc blende (ZB) phases. The ratio of WZ and ZB phases can be tuned by adjusting the solvent ratio and reaction time to construct type I junction and effectively separate the photogenerated electron–hole pair. Under visible-light illumination, the optimal photocatalytic activity of the prepared material reaches 7.96 mmol h−1 g−1, and the quantum efficiency is 36.7% at 420 nm, which is three times higher than that of any single-phase sample (cubic or hexagonal phase) and maintains high photocatalytic stability as well. It is expected that this work will provide a feasible prospect for the practical application of high-efficiency homogeneous junction photocatalysts.
First-principles investigation of a new 2D magnetic crystal: Ferromagnetic ordering and intrinsic half-metallicity
Authors: Li B. G. , Zheng Y. F. , Cui H. , Wang P. , Zhou T. W. , Wang D. D. , Chen H. , Yuan H. K.
Published: June 2020

The development of two-dimensional (2D) magnetic materials with half-metallic characteristics is of great interest because of their promising applications in spintronic devices with high circuit integration density and low energy consumption. Here, by using density functional theory calculations, ab initio molecular dynamics, and Monte Carlo simulation, we study the stability, electronic structure, and magnetic properties of a OsI3 monolayer, of which crystalline bulk is predicted to be a van der Waals layered ferromagnetic (FM) semiconductor. Our results reveal that the OsI3 monolayer can be easily exfoliated from the bulk phase with small cleavage energy and is energetically and thermodynamically stable at room temperature. Intrinsic half-metallicity with a wide bandgap and FM ordering with an estimated TC = 35 K are found for the OsI3 monolayer. Specifically, the FM ordering can be maintained under external biaxial strain from −2% to 5%. The in-plane magnetocrystalline anisotropy energy of the 2D OsI3 monolayer reaches up to 3.89 meV/OsI3, which is an order larger than that of most magnetic 2D materials such as the representative monolayer CrI3. The excellent magnetic features of the OsI3 monolayer therefore render it a promising 2D candidate for spintronic applications.
Factors associated with hepatitis A virus infection among HIV-positive patients before and after implementation of a hepatitis A virus vaccination program at a medical centre in central Taiwan
Authors: Lin Jia-Juen , Lee Yuan-Ti , Yang Hao-Jan
Published: June 2020

Background Taiwan government has promoted the administration of a hepatitis A vaccine at public expense for high-risk groups as a preventive measure after the outbreak of hepatitis A virus (HAV) infections in 2015. The aim of this study was to evaluate the efficacy of such vaccination policy in patients with human immunodeficiency virus (HIV). Methods: From January 2016 to July 2017, we enrolled 658 HIV-positive male participants. Participants were stratified into anti-HAV-positive (n = 165) and anti-HAV-negative (n = 493) groups. A total of 364 anti-HAV-negative patients received vaccination against HAV and were followed up for 1.5 years. A Cox regression model was used to estimate the effects of factors predicting positive anti-HAV detection after vaccination. Results: Patients with HIV had an anti-HAV-positive prevalence of 25.1% before vaccination. Of the 364 patients inoculated with the first dose of vaccine, 58.0% received the second dose. Seroresponse rates were 50.0% and 80.6%, respectively. Antibody production was 30.0% lower in patients with a CD4 T-cell count <200 cells/µL (adjusted relative risk (ARR) = 0.7; 95% confidence interval (CI) = 0.5–0.9) compared with those with 500 cells/µL. Hepatitis C co-infection reduced the production of antibodies by 50.0% (ARR = 0.5; 95% CI = 0.2–0.8). Conclusion: This study suggests that vaccination against hepatitis A be administered when the immunity of an HIV-positive patient is strong. The promotion of the current vaccination policy against hepatitis A in Taiwan has improved the vaccination rate; the response rate for receiving one dose of the vaccine doubled.
Predicting mortality from 57 economic, behavioral, social, and psychological factors
Authors: Puterman Eli , Weiss Jordan , Hives Benjamin A. , Gemmill Alison , Karasek Deborah , Mendes Wendy Berry , Rehkopf David H.
Published: June 2020

Significance

In our prospective study using nationally representative data from 13,611 adults in the US Health and Retirement Study, we used traditional and machine-learning statistical approaches to reveal the most important factors across the behavioral and social sciences that predict mortality in older adults. In the study, we found that top predictors of mortality spanned all investigated domains, opening up opportunities for future hypothesis generation in observational and clinical studies and the identification of potential new targets for screening and policy.
Cost, risk, and avoidance of inbreeding in a cooperatively breeding bird
Authors: Leedale Amy E. , Simeoni Michelle , Sharp Stuart P. , Green Jonathan P. , Slate Jon , Lachlan Robert F. , Robinson Elva J. H. , Hatchwell Ben J.
Published: June 2020

Significance

Inbreeding reduces fitness leading to selection for incest avoidance in many organisms. Passive processes, such as sex-biased dispersal, may reduce inbreeding risk, but when dispersal is limited, inbreeding may still be minimized by animals actively recognizing and discriminating kin from nonkin when choosing mates. We investigated inbreeding costs, risk, and avoidance in a cooperative bird species in which opposite-sex adults disperse locally to breed and frequently associate. We identified a reduction in fitness in inbred individuals and have shown that despite a substantial inbreeding risk, breeders alleviate this by discriminating against close kin as partners. We show that the increased vocal similarity among relatives offers a probable recognition mechanism for this observed level of kin discrimination during mate choice.
Closing and opening of the RNA polymerase trigger loop
Authors: Mazumder Abhishek , Lin Miaoxin , Kapanidis Achillefs N. , Ebright Richard H.
Published: June 2020

Significance

During transcription elongation at saturating nucleotide concentrations, RNA polymerase (RNAP) performs ∼50 nucleotide-addition cycles every second. The RNAP active center contains a structural element, termed the trigger loop (TL), that has been suggested, but not previously shown, to open to allow a nucleotide to enter and then to close to hold the nucleotide in each nucleotide-addition cycle. Here, using single-molecule fluorescence spectroscopy to monitor distances between a probe incorporated into the TL and a probe incorporated elsewhere in the transcription elongation complex, we show that TL closing and opening occur in solution, define time scales and functional roles of TL closing and opening, and, most crucially, demonstrate that one cycle of TL closing and opening occurs in each nucleotide-addition cycle.
Bacterial metabolism rescues the inhibition of intestinal drug absorption by food and drug additives
Authors: Zou Ling , Spanogiannopoulos Peter , Pieper Lindsey M. , Chien Huan-Chieh , Cai Wenlong , Khuri Natalia , Pottel Joshua , Vora Bianca , Ni Zhanglin , Tsakalozou Eleftheria , Zhang Wenjun , Shoichet Brian K. , Giacomini Kathleen M. , Turnbaugh Peter J.
Published: June 2020

Significance

Food and drug products are supplemented with small molecules called excipients that are assumed to be inert. In this study, we screened a collection of common oral excipients and identified 24 that inhibit intestinal drug transport, including the common excipient FD&C Red No. 40, which decreased drug absorption in mice. Excipient inhibitors were enriched for azo dyes, which human gut bacteria could metabolize, producing metabolites that no longer inhibit intestinal drug transporter activity. This work demonstrates the unintended consequences of oral excipients and a beneficial role for the gut microbiome in limiting these unfavorable effects.
DNA-induced 2′3′-cGAMP enhances haplotype-specific human STING cleavage by dengue protease
Authors: Su Chan-I , Kao Yu-Ting , Chang Chao-Chen , Chang Yao , Ho Tzong-Shiann , Sun H. Sunny , Lin Yi-Ling , Lai Michael M. C. , Liu Yu-Huei , Yu Chia-Yi
Published: June 2020

Significance

Dengue virus (DENV) antagonizes the DNA sensing cGAS-STING pathway to subvert innate immunity, but how DENV protease-mediated human STING cleavage contributes to DENV pathogenesis remains obscure. Here, we found that STING haplotype frequency varies among different subhuman populations, and different haplotypes respond differently to DENV protease. The cleavage of a DENV protease-sensitive STING can be further enhanced by coculture with neighboring cells producing 2′3′-cGAMP, either by DNA transfection of cGAS or by reactivating Epstein–Barr virus from latent infection. Thus, DENV infection trims down human STING-mediated innate immunity in a haplotype-specific manner. The genetic background of host STING and bystander coinfection of pathogens triggering 2′3′-cGAMP production may be the missing link between STING cleavage and DENV pathogenesis.
Minimal cobalt metabolism in the marine cyanobacterium
Prochlorococcus
Authors: Hawco Nicholas J. , McIlvin Matthew M. , Bundy Randelle M. , Tagliabue Alessandro , Goepfert Tyler J. , Moran Dawn M. , Valentin-Alvarado Luis , DiTullio Giacomo R. , Saito Mak A.
Published: June 2020

Significance

Photosynthetic phytoplankton are the foundation of marine ecosystems. Their growth in the sunlit ocean depends on ample supply of over a dozen essential elements. Of these elemental nutrients, the metal cobalt is found at the lowest concentrations in seawater, but it is unknown whether cobalt scarcity impacts phytoplankton growth. We have measured minimum cobalt requirements of the photosynthetic bacterium
Prochlorococcus
, which flourishes in nutrient-poor regions of the ocean where many other phytoplankton cannot survive.
Prochlorococcus
can grow with less than 50 cobalt atoms per cell, an extraordinarily small requirement that explains how this organism can persist in low-cobalt environments. These results enable predictions of how marine ecosystems respond to climate-driven changes in nutrient supply.
Subunit composition of the mammalian serine-palmitoyltransferase defines the spectrum of straight and methyl-branched long-chain bases
Authors: Lone Museer A. , Hülsmeier Andreas J. , Saied Essa M. , Karsai Gergely , Arenz Christoph , von Eckardstein Arnold , Hornemann Thorsten
Published: June 2020

Significance

Sphingolipids (SLs) are complex lipids that constitute hundreds of subspecies. All SLs share a long-chain base (LCB) as a defining structural component. LCBs are formed by serine-palmitoyltransferase (SPT) in the first and rate-limiting step of SL de novo synthesis. SPT consists of three subunits that show tissue-specific expression. In presence of the SPTLC3 subunit, the enzyme forms a spectrum of straight and branched LCBs with distinct biochemical and biophysical properties. This alters the composition of cellular membranes and might influence the dynamics of membrane-related transport and signaling events. SPTLC3 is particularly abundant in skin, and changes in SPT activity are related to dermal pathologies. Genetic variants of SPTLC3 are associated with metabolic conditions such as dyslipidemia and atherosclerosis.
Plasmon-enabled degradation of organic micropollutants in water by visible-light illumination of Janus gold nanorods
Authors: Wei Haoran , Loeb Stephanie K. , Halas Naomi J. , Kim Jae-Hong
Published: June 2020

Significance

The presence of organic micropollutants, resulting from pesticide, solvent, detergent, or pharmaceutical use, in drinking water sources poses a significant threat to human health. Degrading these dangerous pollutants using advanced oxidation processes is a desirable but highly energy-intensive treatment option. Here, we report the solar oxidation of organic micropollutants, facilitated by nanorod particles specially designed both for photocatalytic reactivity and for stability under actively transforming water conditions induced by the photocatalytic process itself. Gold Janus nanorods, designed to harvest visible and near-infrared light, are demonstrated to cooperatively activate persulfate ions to generate free radicals for the oxidative decomposition of recalcitrant pollutants. This material platform presents an alternative approach to utilize sunlight for low-cost water purification.
HGT in the human and skin commensal
Malassezia
: A bacterially derived flavohemoglobin is required for NO resistance and host interaction
Authors: Ianiri Giuseppe , Coelho Marco A. , Ruchti Fiorella , Sparber Florian , McMahon Timothy J. , Fu Ci , Bolejack Madison , Donovan Olivia , Smutney Hayden , Myler Peter , Dietrich Fred , Fox David , LeibundGut-Landmann Salomé , Heitman Joseph
Published: June 2020

Significance

Malassezia
species are the main fungal components of the mammalian skin microbiome and are associated with a number of skin disorders. Recently,
Malassezia
has also been found in association with Crohn’s disease and with pancreatic cancer. The elucidation of the molecular bases of skin adaptation by
Malassezia
is critical to understand its role as commensal and pathogen. In this study we employed evolutionary, molecular, biochemical, and structural analyses to demonstrate that the bacterially derived flavohemoglobins acquired by
Malassezia
through horizontal gene transfer resulted in a gain of function critical for nitric oxide detoxification and resistance to nitrosative stress. Our study underscores horizontal gene transfer as an important force modulating
Malassezia
evolution and niche adaptation.
Photo–cross-linkable, insulating silk fibroin for bioelectronics with enhanced cell affinity
Authors: Ju Jie , Hu Ning , Cairns Dana M. , Liu Haitao , Timko Brian P.
Published: June 2020

Significance

Recent advances in bioelectronics have opened avenues toward hybrid engineered tissues with embedded devices that could monitor, modulate, or otherwise augment cellular function. In order to achieve these “cyborgs,” however, both devices and electronic interconnects must stably integrate with the surrounding tissue. We investigated a photo–cross-linkable silk fibroin (PSF) derivative that could be selectively cross-linked using conventional photolithography. We found that PSF was an ideal candidate for bioelectronic scaffolds: it was electrically insulating and so could passivate electronic interconnects, presented amenable surface chemistry to promote cellular adhesion, and could be realized as freestanding, three-dimensional constructs. PSF-based scaffolds are compatible with a wide variety of devices and tissues, and so could enable new classes of hybrid systems.
A basal ganglia-like cortical–amygdalar–hypothalamic network mediates feeding behavior
Authors: Barbier Marie , Chometton Sandrine , Pautrat Arnaud , Miguet-Alfonsi Carole , Datiche Frédérique , Gascuel Jean , Fellmann Dominique , Peterschmitt Yvan , Coizet Véronique , Risold Pierre-Yves
Published: June 2020

Significance

The network connecting the insular cortex, the central nucleus of the amygdala, and a caudal hypothalamic nuclear complex including the parasubthalamic nucleus (PSTN) is of interest due to its role in controlling feeding behavior. Here, we show that the organization of this network is similar to that of the basal ganglia network, implying that both fit within a simplified structural plan of the forebrain. Then, we demonstrate that the PSTN complex modulates behavior in response to hedonic factors normally inducing a “reward effect.” The PSTN complex is involved in a “non-feed” response equivalent of a “non-reward” evaluation: “I don’t want to consume this food, recognized as good, because I am not in a conducive emotional or physiological state.”
Modulation of the bacterial CobB sirtuin deacylase activity by N-terminal acetylation
Authors: Parks Anastacia R. , Escalante-Semerena Jorge C.
Published: June 2020

Significance

N-terminal protein acetylation is poorly understood in bacteria. Herein, we report the identification of an Nα acetyltransferase (NAT) that modulates the activity of a sirtuin deacylase in a human pathogen. This is significant because the alluded enzyme (named
N
-acyltransferase A [NatA], formerly YiaC) is a prokaryotic non-Rim–type NAT, and N
-
terminal acetylation of a bacterial sirtuin has not been reported. Also significant is the fact that NatA affects the metabolism of acetate, a short-chain fatty acid known to play an important role in pathogenesis in the human gut.
Laccase3-based extracellular domain provides possible positional information for directing Casparian strip formation in
Arabidopsis
Authors: Zhuang Yan , Zuo Daqing , Tao Yihan , Cai Huaqing , Li Lei
Published: June 2020

The Casparian strip (CS) is a tight junction-like structure formed by lignin impregnation on the walls of endodermal cells in plant roots. The CS membrane domain (CSD
M
), demarked by the CASP proteins, is important for orienting lignification enzymes. Here, we report that an endodermis-expressed multicopper oxidase, LACCASE3 (LAC3) in
Arabidopsis
, locates to the interface between lignin domains and the cell wall during early CS development prior to CASP1 localizing to CSD
M
and eventually flanks the mature CS. Pharmacological perturbation of LAC3 causes dispersed localization of CASP1 and compensatory ectopic lignification. These results support the existence of a LAC3-based CS wall domain which coordinates with CSD
M
to provide bidirectional positional information that guides precise CS lignification.
Cell profiling of mouse acute kidney injury reveals conserved cellular responses to injury
Authors: Kirita Yuhei , Wu Haojia , Uchimura Kohei , Wilson Parker C. , Humphreys Benjamin D.
Published: June 2020

Significance

Single nucleus RNA sequencing revealed gene expression changes during repair after acute kidney injury. We describe a small population of proximal tubule cells that fail to repair (FR-PTCs). Since this subpopulation expresses abundant proinflammatory and profibrotic genes, it may represent a new therapeutic target to improve repair and reduce fibrosis after AKI.
Growth and arrest of topological cycles in small physical networks
Authors: Sirk Timothy W.
Published: June 2020

The chordless cycle sizes of spatially embedded networks are demonstrated to follow an exponential growth law similar to random graphs if the number of nodes

N

x

is below a critical value

N

*

. For covalent polymer networks, increasing the network size, as measured by the number of cross-link nodes, beyond

N

*

results in a crossover to a new regime in which the characteristic size of the chordless cycles

h

*

no longer increases. From this result, the onset and intensity of finite-size effects can be predicted from measurement of

h

*

in large networks. Although such information is largely inaccessible with experiments, the agreement of simulation results from molecular dynamics, Metropolis Monte Carlo, and kinetic Monte Carlo suggests the crossover is a fundamental physical feature which is insensitive to the details of the network generation. These results show random graphs as a promising model to capture structural differences in confined physical networks.
Instant tough bioadhesive with triggerable benign detachment
Authors: Chen Xiaoyu , Yuk Hyunwoo , Wu Jingjing , Nabzdyk Christoph S. , Zhao Xuanhe
Published: June 2020

Significance

Owing to potential advantages including ease of use, airtight or watertight sealing, and minimal tissue damage, bioadhesives have been intensively studied and developed as an alternative to sutures and staples to close wounds, achieve hemostasis, and attach and immobilize implantable devices. However, existing bioadhesives have limitations including slow adhesion formation, weak bonding, low biocompatibility, poor mechanical match with tissues, and/or lack of triggerable benign detachment. In this work, we report a bioadhesive capable of instant tough adhesion and triggerable benign detachment that can potentially address all the above-mentioned limitations. The current work not only develops a bioadhesive with superior performances but also advances the understanding of wet adhesion.
The function of GORASPs in Golgi apparatus organization in vivo
Authors: Grond Rianne , Veenendaal Tineke , Duran Juan M. , Raote Ishier , van Es Johan H. , Corstjens Sebastiaan , Delfgou Laura , El Haddouti Benaissa , Malhotra Vivek , Rabouille Catherine
Published: June 2020

In vitro experiments have shown that GRASP65 (GORASP1) and GRASP55 (GORASP2) proteins function in stacking Golgi cisternae. However, in vivo depletion of GORASPs in metazoans has given equivocal results. We have generated a mouse lacking both GORASPs and find that Golgi cisternae remained stacked. However, the stacks are disconnected laterally from each other, and the cisternal cross-sectional diameters are significantly reduced compared with their normal counterparts. These data support earlier findings on the role of GORASPs in linking stacks, and we suggest that unlinking of stacks likely affects dynamic control of COPI budding and vesicle fusion at the rims. The net result is that cisternal cores remain stacked, but cisternal diameter is reduced by rim consumption.
Transverse Propagation Characteristics and Coherent Effect of Gaussian Beams*
Authors: Xiang Fei , Zhang Lin , Chen Tao , Zhong Yuan-Hong , Li Jin
Published: June 2020

As an important electromagnetic field in experiment, Gaussian beams have non-vanishing longitudinal electric and magnetic components that generate significant energy fluxes on transverse directions. We focus on the transverse energy flux and derive the theoretical propagation properties. Unlike the longitudinal energy flux, the transverse energy flux has many unique physical behaviors, such as the odd symmetry on propagation, slower decay rate on resonant condition. By means of the characteristics of transverse energy flux, it is feasible to find the suitable regions where the information of coherent lights could be extracted exactly. With the typical laser parameters, we simulate the energy fluxes on receiver surface and analyze the corresponding distribution for the coherent light beams. Especially for coherent lights, the transverse energy flux on the y–z plane with x = 0 and x–z plane with y = 0, contains pure coherent information. Meanwhile, in the transverse distance |y| < 2W
0 (W
0 is the waist radius) and |x| < W
0/3 the coherent information could also be extracted appropriately.
An All-Polarization-Maintaining Multi-Branch Optical Frequency Comb for Highly Sensitive Cavity Ring-Down Spectroscopy*
Authors: Ning Kai , Hou Lei , Fan Song-Tao , Yan Lu-Lu , Zhang Yan-Yan , Rao Bing-Jie , Zhang Xiao-Fei , Zhang Shou-Gang , Jiang Hai-Feng
Published: June 2020

We demonstrate a multi-branch all polarization-maintaining Er:fiber frequency comb with five application ports for precise measurement of atomic/molecular transition frequencies in the near-infrared region. A fully stabilized Er:fiber frequency comb with a nonlinear amplifying loop mirror is achieved. The in-loop relative instability of stabilized carrier-envelope-offset frequency is 5.6 × 10−18 at 1 s integration time, while that of the repetition rate is well below 1.8 × 10−12 limited by the measurement noise floor of the commercial frequency counter. Five application ports are individually optimized for applications with different wavelengths (1064 nm, 1083 nm, 1380 nm, 1637 nm and 1750 nm). The beat note between the optical frequency comb and continuous laser exhibits the signal-to-noise ratio of at least 30 dB at a resolution bandwidth of 100 kHz. The in-loop frequency instability of the comb is evaluated to be good enough for measurement of rotation-resolved transitions of molecules below 1 kHz resolution.
Switching between the Functions of Half-Wave Plate and Quarter-Wave Plate Simply by Using a Vanadium Dioxide Film in a Terahertz Metamaterial*
Authors: Zhao Jian-Xing , Song Jian-Lin , Zhou Yao , Liu Yi-Chao , Zhou Jian-Hong
Published: June 2020

We propose a switchable THz metamaterial that can be switched between two functions of half-wave plate and quarter-wave plate. The two switchable functions can be simply achieved by inserting a VO2 film in the metamaterial design. Finite-difference time-domain (FDTD) simulation results show that the proposed metamaterial can convert x-polarized incident wave to y-polarized reflected wave when VO2 is at metal phase, and convert x-polarized wave to circularly polarized wave when VO2 is at insulator phase. The metamaterial performs well in the two functions, i.e., the same broad working frequency band and near perfect polarization conversion. The switching effect originates from the switchable Fabry–Pérot cavity length induced by the phase change of VO2. We believe that our findings provide a reference in designing switchable metamaterials.
Detection and Location of a Target in Layered Media without Prior Knowledge of Medium Parameters*
Authors: Li Jian , Yang Hong-Juan , Ma Jun , Gao Xiang , Li Jun-Hong , Cheng Jian-Zheng , Wang Wen , Wang Cheng-Hao
Published: June 2020

Without prior knowledge of medium parameters, a method is proposed to detect and locate a target in layered media. Experiments were carried out for liquid/liquid and solid/liquid layered media, and the location of a target in them was obtained using three methods combined, i.e., the least-square method, the method of finding minimum dispersal degree of target distribution, and the snapshot time reversal and reverse time migration mixed method. The medium parameters, i.e., the acoustic velocities of upper and lower media as well as the thickness of the upper medium, were inversed simultaneously. The results show that the position of target is consistent with its actual position. Thus, the detection and location of a target in layered media are achieved without prior knowledge of medium parameters, and it overcomes the difficulty that the common time reversal method only detects the target, but cannot locate it.
Pressure-Induced Topological and Structural Phase Transitions in an Antiferromagnetic Topological Insulator*
Authors: Pei Cuiying , Xia Yunyouyou , Wu Jiazhen , Zhao Yi , Gao Lingling , Ying Tianping , Gao Bo , Li Nana , Yang Wenge , Zhang Dongzhou , Gou Huiyang , Chen Yulin , Hosono Hideo , Li Gang , Qi Yanpeng
Published: June 2020

Recently, natural van der Waals heterostructures of (MnBi2Te4)
m
(Bi2Te3)
n
have been theoretically predicted and experimentally shown to host tunable magnetic properties and topologically nontrivial surface states. We systematically investigate both the structural and electronic responses of MnBi2Te4 and MnBi4Te7 to external pressure. In addition to the suppression of antiferromagnetic order, MnBi2Te4 is found to undergo a metal–semiconductor–metal transition upon compression. The resistivity of MnBi4Te7 changes dramatically under high pressure and a non-monotonic evolution of ρ (T) is observed. The nontrivial topology is proved to persist before the structural phase transition observed in the high-pressure regime. We find that the bulk and surface states respond differently to pressure, which is consistent with the non-monotonic change of the resistivity. Interestingly, a pressure-induced amorphous state is observed in MnBi2Te4, while two high-pressure phase transitions are revealed in MnBi4Te7. Our combined theoretical and experimental research establishes MnBi2Te4 and MnBi4Te7 as highly tunable magnetic topological insulators, in which phase transitions and new ground states emerge upon compression.
Symmetry Breaking and Reversible Hydrogenation of Two-Dimensional Semiconductor Sn2Bi*
Authors: Wang Xuguang , Xia Bingyu , Gou Jian , Cheng Peng , Xu Yong , Chen Lan , Wu Kehui
Published: June 2020

The hydrogenation of two-dimensional (2D) systems can efficiently modify the physical and chemical properties of materials. Here we report a systematic study on the hydrogenation of 2D semiconductor Sn2Bi on Si(111) by scanning tunneling microscopy experiments and first principle calculations. The unique butterfly-like and trench-like features were observed for single H adsorption sites and hydrogen-saturated surfaces respectively, from which the bridge-site adsorption geometry can be unambiguously determined. The structural model was further confirmed by the theoretical calculations, which is in good agreement with the experimental observation. In addition, the hydrogenation is found to vanish the flat band of Sn2Bi and increase the band gap obviously.
Bound States in the Continuum in One-Dimensional Dimerized Plasmonic Gratings*
Authors: Huang Chen , Song Qian-Ju , Hu Peng , Dai Shi-Wei , Xiang Hong , Han Dezhuan
Published: June 2020

A simple one-dimensional subwavelength plasmonic grating can support symmetry protected bound states in the continuum (BICs), but not necessarily for the non-symmetry protected BICs. By dimerizing the lattice, non-symmetry protected BIC can be supported on the dimerized grating and can be tuned readily. The mechanism for the BICs in the dimerized grating is interpreted in the viewpoint of interference between the electromagnetic multipoles.
Gold-Nanoparticles/Boron-Doped-Diamond Composites as Surface-Enhanced Raman Scattering Substrates*
Authors: Zhang Ai-Qi , Wang Qi-Liang , Gao Ying , Cheng Shao-Heng , Li Hong-Dong
Published: June 2020

By vacuum sputtering and annealing processes of gold (Au) films on boron-doped diamond (BDD) surfaces, Au-nanoparticles/BDD (AuNP/BDD) composite substrates were prepared as surface-enhanced Raman scattering (SERS) substrates. The SERS performances of the substrate were investigated using methylene blue molecule as a probe. With the AuNPs having an average diameter of 20 nm, high performance of SERS was achieved at an enhancement factor of 9 × 105, arising from the synergistic effect of electromagnetic enhancement from AuNPs and chemical enhancement from diamond. The AuNP/BDD substrate is demonstrated to be highly sensitive, reproducible, stable, and reusable for the SERS examination. Due to the facile preparation process and controllable surface morphology, the AuNP/BDD substrates are favorable as a high performance SERS platform performed in practical applications.
Mid-Infrared InAs/GaSb Superlattice Planar Photodiodes Fabricated by Metal–Organic Chemical Vapor Deposition*
Authors: Zhao Yu , Teng Yan , Miao Jing-Jun , Wu Qi-Hua , Gao Jing-Jing , Li Xin , Hao Xiu-Jun , Zhao Ying-Chun , Dong Xu , Xiong Min , Huang Yong
Published: June 2020

Mid-wavelength infrared planar photodiodes were demonstrated, in which both the epitaxy growth of InAs/GaSb superlattices and the thermal diffusion of p-type dopant were performed in production-scale metal–organic chemical vapor deposition reactors. The formation of a planar homojunction was confirmed by secondary ion mass spectroscopy and its I–V characteristics. A cut-off wavelength around 5 μm was determined in 77 K optical characterization, and photo-current as high as 600 nA was collected from a reverse-biased planar diode of 640 μm diameter. These preliminary results were obtained despite the structural degradation revealed by x-ray diffraction, and we attribute the degradation to the concert of thermal annealing and high Zn concentration behind the diffusion front.
Characterization of the Topological Features of Catalytic Sites in Protein Coevolution Networks*
Authors: Xu Xiu-Lian , Shi Jin-Xuan
Published: June 2020

The knowledge of sequence and structural properties of residues in the catalytic sites of enzymes is important for understanding the physiochemical basis of enzymatic catalysis. We reveal new features of the catalytic sites by analyzing the coevolutionary behavior of amino acid sequences. By performing direct coupling analysis of the sequences of homologous proteins, we construct the coevolution networks at the residue level. Based on the analysis of the topological features of the coevolution networks for a dataset including 20 enzymes, we show that there is significant correlation between the catalytic sites and topological features of protein coevolution networks. Residues at the catalytic center often correspond to the nodes with high values of centralities in the networks as characterized by the degree, betweenness, closeness, and Laplacian centrality. The results of this work provide a possible way to extract key coevolutionary information from the sequences of enzymes, which is useful in the prediction of catalytic sites of enzymes.