bluuebunny/crossref_metadata_2025 huggingface dataset:
Multipolar interactions in Si sphere metagratings
Authors: Panagiotidis E. , Almpanis E. , Stefanou N. , Papanikolaou N.
Published: September 2020

A thorough theoretical study of the optical properties of periodic Si nanosphere arrays is undertaken, placing a particular emphasis on the synergy between multipolar, electric and magnetic, Mie resonances, which occur in high-refractive-index nanoparticles and can lead to a rich variety of phenomena ranging from perfect reflection to controlled diffraction. Systematic calculations using the layer-multiple-scattering method, which we properly extended to describe periodic arrays with many different scatterers per unit cell, in conjunction with finite-element simulations are presented. It is shown that rectangular arrays of pairs of Si nanospheres can efficiently diffract light in reflection or transmission mode at large angles as well as split light with minimum backreflection by properly adjusting the geometry of the structure. Our rigorous full-electrodynamic calculations highlight the importance of higher-order multipoles, which are not taken into account in the commonly employed dipole approximation, in the description of these effects.
Impact of electromagnetic effects on macroscopic dynamics of blobs in hot low-
β
edge plasma of fusion devices
Authors: Stepanenko A. A.
Published: September 2020

The impact of electromagnetic effects on macroscopic dynamics of blobs in hot low-β (β<me/mi) edge plasma of fusion devices is analyzed. The physical model governing filament dynamics is presented. The qualitative analysis of the blob motion in electrostatic and electromagnetic regimes is performed. The scalings for the plasma potential and filament advection velocity are obtained along with the estimates of plasma parameters, for which the physics of Alfvén waves and skin effect can have an impact on the filament motion. It is shown that required edge/scrape-off layer conditions can be found in modern tokamaks. Analytical expressions for the distributions of the parallel current and electrostatic potential in a blob, containing electrostatic and electromagnetic contributions, are derived. It is demonstrated that in sufficiently hot, weakly resistive plasma the electromagnetic effects can lead to noticeable variations of the potential along the magnetic field lines distorting the blob propagation pattern in contrast to the electrostatic case. Results of the theoretical analysis are compared with results of 3D BOUT++ modeling, which show that in the electromagnetic limit, the macroscopic motion of blobs can exhibit ballooning features due to the emission of Alfvén waves, absent in electrostatic simulations. It is concluded that, at least in the near scrape-off layer region of fusion devices, electromagnetic models of plasma dynamics may be appropriate for the analysis of blob motion instead of electrostatic ones.
The structure of reconstructed flows in latent spaces
Authors: Uribarri Gonzalo , Mindlin Gabriel B.
Published: September 2020

Reconstructing the flow of a dynamical system from experimental data has been a key tool in the study of nonlinear problems. It allows one to discover the equations ruling the dynamics of a system as well as to quantify its complexity. In this work, we study the topology of the flow reconstructed by autoencoders, a dimensionality reduction method based on deep neural networks that has recently proved to be a very powerful tool for this task. We show that, although in many cases proper embeddings can be obtained with this method, it is not always the case that the topological structure of the flow is preserved.
Multibit optoelectronic memory using graphene/diamond (carbon sp2-sp3) heterojunctions and its arithmetic functions
Authors: Ueda K. , Mizuno Y. , Asano H.
Published: September 2020

This work demonstrates that graphene/diamond (carbon sp2-sp3) heterojunctions can be used as multibit optoelectronic memory, where light information is stored as multilevel resistance in a nonvolatile manner. The carbon heterojunctions exhibit a large memory switching ratio of ∼104 and a retention time of >100 min, which allows for multilevel and nonvolatile data storage of optical information. The carbon heterojunctions also exhibit an apparent response to optical pulses, and the output current (conductivity of the junctions) increased linearly in response to the total number of optical pulses. Simple optical arithmetic operations such as accumulation, subtraction, and counting can be performed by using the multiple resistance states of the heterojunctions. The carbon heterojunctions have light sensing, memory, and arithmetic functions in a single device, and they are expected to pave the way for the production of innovative optical computing devices with multifunctional integration of sensing, memory, and calculation functions.
A high-pressure reactor coupled to synchrotron radiation photoionization mass spectrometry
Authors: You Rui , Yu Shengsheng , Yang Jiuzhong , Pan Yang , Huang Weixin
Published: September 2020

A high-pressure reactor was designed and coupled to synchrotron radiation photoionization mass spectrometry (SR-PIMS), which realizes the molecular-beam sampling and detection of gaseous products of high-pressure reactions. The reaction pressure can be controlled by varying the size of the pinhole of the pressure-bearing pipe. As tested by the Fischer–Tropsch synthesis (FTS) catalyzed by Co/SiO2 at 230 °C, the reaction pressure of our setup can reach 1.3 MPa with a pinhole size of 50 µm and 0.16 MPa with a pinhole size of 150 µm. The FTS products were successfully online detected by SR-PIMS, and the photoionization efficiency spectra of selected products were acquired for unambiguous identification of the detected signals. Meanwhile, time-resolved SR-PIMS spectra were acquired with a temporal resolution of 10 s. The characterization results demonstrate that the product distribution (C2–C4, C5–C11, and C12+) of FTS depends on the reaction pressure, where a high pressure facilitates the formation of long-chain hydrocarbons. With the advantages of detecting unstable intermediates and distinguishing isomers, this setup will be useful for fundamental studies of high-pressure heterogeneous catalytic reactions.
Time-domain modeling analysis of pulsed eddy current testing on ferromagnetic casing
Authors: Sun Hu , Shi Yibing , Zhang Wei
Published: September 2020

Pulsed eddy current has attracted increasing attention to ferromagnetic metal material evaluation since it possesses low power consumption and abundant frequency spectrum advantages. However, when a current source is applied to generate the pulse excitation signal in eddy current testing, the inductance of driver coil induces a large reverse electromotive force in the excitation circuit, which distorts the pulse excitation signal as the excitation circuit hardly satisfies the severe power and stability requirements for counteracting the reverse induced electromotive force. Therefore, a pulsed eddy current field excited by a voltage-driven coil placed concentrically to a ferromagnetic casing is studied, and the analytic solutions of it are formulated in this paper. In contrast to current source based pulsed eddy current testing methods, the electromotive force induced by the coil’s inductance and eddy current is analyzed. Furthermore, a new pulse excitation function is adopted and induced electromotive force equations of pick-up coils are formulated based on the superposition principle of magnetic field. Finally, the theoretical results are verified by experiments.
An accurate 5D potential energy surface for H3O+–H2 interaction
Authors: Demes S. , Lique F. , Faure A. , Rist C.
Published: September 2020

Modeling of the observational spectra of H3O+ allows for a detailed understanding of the interstellar oxygen chemistry. While its spectroscopy was intensively studied earlier, our knowledge about the collision of H3O+ with the abundant colliders in the interstellar medium is rather limited. In order to treat these collisional excitation processes, it is first necessary to calculate the potential energy surface (PES) of the interacting species. We have computed the five-dimensional rigid-rotor PES of the H3O+–H2 system from the explicitly correlated coupled-cluster theory at the level of singles and doubles with perturbative corrections for triple excitations [CCSD(T)-F12] with the moderate-size augmented correlation-consistent valence triple zeta (aug-cc-pVTZ) basis set. The well depth of the PES is found to be rather large, about 1887.2 cm−1. The ab initio potential was fitted over an angular expansion in order to effectively use it in quantum scattering codes. As a first application, we computed dissociation energies for the different nuclear spin isomers of the H3O+–H2 complex.
On the receptivity of surface plasma actuation in high-speed boundary layers
Authors: Wang Yutian , Li Yiwen , Liu Jianxin , Li Yinghong
Published: September 2020

Significant amounts of work have been conducted in the area of plasma flow control, while the receptivity of plasma actuation in high-speed boundary layers has not had much attention over the last two decades. In the present study, the receptivity of a Mach 4.5 flat-plate boundary layer to plasma heating actuation produced by pulsed-DC surface dielectric barrier discharge (SDBD) has been studied by direct numerical simulation (DNS) and stability analysis. With the help of multimode decomposition technology, the amplitude of normal modes can be obtained. The results show that both fast and slow modes can be excited by plasma actuation, and the receptivity maximum is observed near the lower neutral branch. Because the pulsed-DC SDBD actuation is typical periodic pulse signals, when the total power remains constant, the Fourier components with multiples of actuation frequency have the same energy, regardless of the waveform, period, and width of the actuation signal. Such characteristics benefit the robustness of the pulsed-DC SDBD actuator. A theoretical prediction method by combining the receptivity model and linear parabolized stability equations is considered in the present study, and good agreement with the DNS results is achieved.
On the equivalence between different averaging schemes in magnetic resonance
Authors: Ganguly Shreyan , Garg Rajat , Ramachandran Ramesh
Published: September 2020

Evolution of quantum mechanical systems under time-dependent Hamiltonians has remained a challenging problem of interest across all disciplines. Through suitable approximations, different averaging methods have emerged in the past for modeling the time-evolution under time-dependent Hamiltonians. To this end, the development of analytic methods in the form of time-averaged effective Hamiltonians has gained prominence over other methods. In particular, the advancement of spectroscopic methods for probing molecular structures has benefited enormously from such theoretical pursuits. Nonetheless, the validity of the approximations and the exactness of the proposed effective Hamiltonians have always remained a contentious issue. Here, in this report, we reexamine the equivalence between the effective Hamiltonians derived from the Magnus formula and Floquet theory through suitable examples in magnetic resonance.
Hand-generated piezoelectric mechanical-to-electrical energy conversion plasma
Authors: Jaenicke Olivia K. , Hita Martínez Federico G. , Yang Jinyu , Im Seong-kyun , Go David B.
Published: September 2020

A transient spark discharge is an atmospheric pressure plasma that has applications in pollutant removal, medicine, water treatment, agriculture, bactericides, and nanomaterial synthesis. Conventional methods of generating transient sparks at atmospheric pressure usually require a high voltage input at nanosecond pulses. Piezoelectric crystals offer a path to creating plasma devices that do not require a high voltage power supply to generate high voltage outputs; they directly transform mechanical energy into electrical energy. This work examines a manually-operated piezoelectric mechanical-to-electrical energy conversion plasma device. Electrical characterization of the plasma discharge generated by this device shows that it behaves as a transient spark, discharging 0.96 mJ over approximately 30 ns, with consistent behavior across multiple consecutive discharges. Although this specific device had a low mechanical-to-plasma energy conversion efficiency of 1.54%, the piezoelectric crystal resets to an equilibrium condition after approximately 8 μs, which suggests that it could be operated with a mechanical input of up to nearly 125 kHz. This work shows the potential of generating plasma in off-the-grid situations using piezoelectric crystals. One particular application of a piezoelectric plasma device is for in situ pollution mitigation or plasma-enhanced combustion, embedding such a device on the high-frequency oscillating or rotating components of internal combustion engines and turbomachinery.
On the cavity-actuated supersonic mixing layer downstream a thick splitter plate
Authors: Tan Jianguo , Li Hao , Noack Bernd R.
Published: September 2020

We propose a cavity as an actuator to actuate the supersonic mixing layer downstream a thick splitter plate. The cavity-actuated case at Re = 1.73 × 105 is simulated using large eddy simulation. The forced dynamics is resolved by the cluster-based network model (CNM) from a probabilistic point of view. Introducing a cavity obtains a 50% increase in the growth rate of vorticity thickness. The recirculation region immediately downstream the trailing edge of the splitter plate is largely reduced, which contributes to the advanced and fast growth of the redeveloping mixing layer. The cavity oscillation induces three-dimensional features that are beneficial to the small-scale mixing. Spectral analysis reveals that the cavity-actuated flow field exhibits the phenomena of the strict frequency-lock and temporal mode-switching. The CNM successfully resolves the intermittent dynamics of the supersonic mixing layer using only ten centroids. The CNM’s outcomes reveal two flow regimes of the unforced case: the Kelvin–Helmholtz vortex and vortex pairing. The cavity oscillation significantly affects the flow patterns of the centroids, which exhibit flow structures closely associated with the wake mode and shear-layer mode of the cavity oscillations. The dynamics of the cavity-actuated case is tamed into a strictly periodic transition loop among ten clusters undergoing the cyclic motion of the cluster energy fluctuation from the maximum to the minimum. Each centroid of the cavity-actuated case transports much more turbulent kinetic energy than that of the unforced case. Overall, the cavity-actuated attractor gets a 3.27 times increase in the energy fluctuation.
Ultra-broadband terahertz absorber based on a multilayer graphene metamaterial
Authors: Liu Ling , Liu Wenwen , Song Zhengyong
Published: September 2020

An ultra-broadband absorber is introduced based on a multilayer graphene structure. Wave absorption of the optimized device is >90% in the bandwidth between 1.12 THz and 3.78 THz. Electric field distributions are studied to analyze the working mechanism. Because of the symmetrical structure, the designed absorber is not sensitive to the polarization state of the incident wave under small angles. The absorber has a reasonable tolerance for incident angles. The working intensity and bandwidth of the absorber are modulated with a wide range of tunability by different Fermi energy levels of graphene. This kind of ultra-broadband terahertz absorbers could have potential applications in a variety of areas, such as terahertz imaging, anti-radar stealth, and electrically adjustable modulation.
Magnetic and magnetocaloric properties of layered van der Waals CrCl3
Authors: Mondal Suchanda , Midya A. , Patidar Manju Mishra , Ganesan V. , Mandal Prabhat
Published: September 2020

We have investigated the magnetic and magnetocaloric properties of van der Waals (vdW) layered CrCl3 from magnetization and heat capacity measurements. CrCl3 exhibits complicated magnetic properties due to the strong competition between the ferromagnetic and antiferromagnetic interactions: a ferromagnetic ordering around 17 K followed by an antiferromagnetic ordering at 14.3 K. A large magnetic entropy change (−ΔSM) of 19 J kg−1 K−1, an adiabatic temperature change (ΔTad) of 6.2 K, and a relative cooling power of 600 J kg−1 are observed for a field change of 7 T near the transition temperature, and the mechanical efficiency (ηm) at 18 K and 0–3 T is 1.17. These values of magnetocaloric parameters are significantly larger than those for CrI3 and other layered vdW systems. The scaling analysis shows that all the rescaled ΔSM(T, H) data collapse into a single curve, which indicates the second order nature of magnetic phase transition. The above results suggest that environmentally friendly CrCl3 can be a phenomenal alternative to very expensive rare-earth material for the magnetic refrigeration for liquefaction of hydrogen.
Breakup morphology of expelled respiratory liquid: From the perspective of hydrodynamic instabilities
Authors: Vadivukkarasan M. , Dhivyaraja K. , Panchagnula Mahesh V.
Published: September 2020

Understanding the breakup morphology of an expelled respiratory liquid is an emerging interest in diverse fields to enhance the efficacious strategies to attenuate disease transmission. In this paper, we present the possible hydrodynamic instabilities associated with expelling the respiratory liquid by a human. For this purpose, we have performed experiments with a cylindrical soap film and air. The sequence of the chain of events was captured with high-speed imaging. We have identified three mechanisms, namely, Kelvin–Helmholtz (K–H) instability, Rayleigh–Taylor (R–T) instability, and Plateau–Rayleigh (P–R) instability, which are likely to occur in sequence. Furthermore, we discuss the multiple processes responsible for drop fragmentation. The processes such as breakup length, rupture, ligament, and drop formation are documented with a scaling factor. The breakup length scales with We−0.17, and the number of ligaments scales as Bo. In addition, the thickness of the ligaments scales as We−0.5. Here, We and Bo represent the Weber and Bond numbers, respectively. It was also demonstrated that the flapping of the liquid sheet is the result of the K–H mechanism, and the ligaments formed on the edge of the rim appear due to the R–T mechanism, and finally, the hanging drop fragmentation is the result of the P–R instability. Our study highlights that the multiple instabilities play a significant role in determining the size of the droplets while expelling a respiratory liquid. This understanding is crucial to combat disease transmission through droplets.
Visualizing droplet dispersal for face shields and masks with exhalation valves
Authors: Verma Siddhartha , Dhanak Manhar , Frankenfield John
Published: September 2020

Several places across the world are experiencing a steep surge in COVID-19 infections. Face masks have become increasingly accepted as one of the most effective means for combating the spread of the disease when used in combination with social-distancing and frequent hand-washing. However, there is an increasing trend of people substituting regular cloth or surgical masks with clear plastic face shields and with masks equipped with exhalation valves. One of the factors driving this increased adoption is improved comfort compared to regular masks. However, there is a possibility that widespread public use of these alternatives to regular masks could have an adverse effect on mitigation efforts. To help increase public awareness regarding the effectiveness of these alternative options, we use qualitative visualizations to examine the performance of face shields and exhalation valves in impeding the spread of aerosol-sized droplets. The visualizations indicate that although face shields block the initial forward motion of the jet, the expelled droplets can move around the visor with relative ease and spread out over a large area depending on light ambient disturbances. Visualizations for a mask equipped with an exhalation port indicate that a large number of droplets pass through the exhale valve unfiltered, which significantly reduces its effectiveness as a means of source control. Our observations suggest that to minimize the community spread of COVID-19, it may be preferable to use high quality cloth or surgical masks that are of a plain design, instead of face shields and masks equipped with exhale valves.
A review and assessment of fish trophic levels in a large reservoir of central Anatolia, Turkey
Authors: Yoğurtçuoğlu Baran , Ekmekçi Fitnat Güler , Karachle Paraskevi K.
Published: August 2020

Estimating trophic levels of fishes plays an important role in shedding light on the trophic interactions in aquatic ecosystems. In this short review, available literature data were collected regarding feeding habits of fishes from Hirfanlı Reservoir, and the fractional trophic levels (TROPHs) were estimated. Following this, the applicability of functional trophic groups (FTG) proposed for marine fishes was tested for freshwater species. Finally, an attempt to draw a general scheme of the trophic guilds of fish species in the reservoir was made. The literature review yielded information on stomach content data of eight native species, and their TROPHs were estimated on the basis of 86 datasets, provided by nine papers. The calculated TROPH values ranged from 2.00±0.00 to 4.50±0.80. The number of cases from which TROPH values are estimated clustered within each of the previously defined FTGs as substantially skewed towards herbivory. The results obtained are a useful tool for applying ecosystem models and management applications for freshwater ecosystems. This work also clearly indicated the need for defining FTG for freshwater fishes that could be different from the marine ones. Such approaches are a solid basis for the maintenance of future conservation planning, especially in reservoirs.
Intergenerational resource sharing and mortality in a global perspective
Authors: Vogt Tobias , Kluge Fanny , Lee Ronald
Published: September 2020

Significance

Intergenerational transfers are like gifts from one age or generation to another, taking place between relatives, such as from parents to children, or through the public sector, such as retirement benefits or health care from taxpayers. Individual-level studies have found health benefits of giving and/or receiving transfers. Here, we address this topic at the societal level using population-level data for 34 countries to measure the generosity of total transfers received, public plus private, summed over all life-cycle stages, and expressed relative to income. Comparing this comprehensive measure across countries, transfer generosity is negatively related to national mortality and positively related to longevity. This result is consistent with a positive effect of prosocial behavior on health.
Anoxic photogeochemical oxidation of manganese carbonate yields manganese oxide
Authors: Liu Winnie , Hao Jihua , Elzinga Evert J. , Piotrowiak Piotr , Nanda Vikas , Yee Nathan , Falkowski Paul G.
Published: September 2020

Significance

When oxygenic photosynthesis evolved is debated with an uncertainty of approximately 1 Gy. It is generally assumed that the oxidation of manganese minerals requires biological catalysis or molecular oxygen and therefore is often used as a proxy for the presence of oxygenic photosynthetic organisms. We show that anoxic, abiotic oxidation of the mineral rhodochrosite (MnCO3) by UV light forms H2and manganite (γ-MnOOH). Our results reveal an alternative mechanism for producing manganese oxides from rhodochrosite in the absence of molecular oxygen. These results demonstrate the potential impact of photogeochemical processes on the redox state of transition metals and hence question the interpretation of the rise of atmospheric oxygen based on the oxidation of transition metals, such as Cr isotopes.
The genetic basis for PRC1 complex diversity emerged early in animal evolution
Authors: Gahan James M. , Rentzsch Fabian , Schnitzler Christine E.
Published: September 2020

Significance

Animals, to maintain patterns of gene expression throughout life, utilize the Polycomb system to repress transcription. Vertebrates have a large number of Polycomb protein complexes, particularly belonging to the Polycomb Repressive Complex 1 (PRC1) family. Here we show that, contrary to current hypotheses, the large number of complexes found in vertebrates appeared early in animal evolution and was subsequently reduced in many lineages. Among the species studied here, only anthozoan cnidarians (corals and sea anemones) and vertebrates have the full set of possible PRC1 complexes and therefore it will be interesting to study their function in these animals. This study highlights the importance of nonstandard model organisms when studying the evolution of processes such as gene silencing by Polycomb.
Supergene evolution via stepwise duplications and neofunctionalization of a floral-organ identity gene
Authors: Huu Cuong Nguyen , Keller Barbara , Conti Elena , Kappel Christian , Lenhard Michael
Published: September 2020

Significance

Heterostyly is an adaptation to promote outbreeding in plants. In heterostylous primroses, plants form flowers either with long styles and low anthers or with short styles and high anthers. This difference is due to a chromosomal segment containing five predicted genes, yet their roles and the evolution of this segment remain unclear. Here we identify the gene responsible for raising the anthers in short-styled flowers. This gene arose by duplication from a classical floral-organ identity gene and gained a novel function. Surprisingly, the responsible chromosomal segment appears to have evolved by stepwise gene duplications rather than duplication of an entire chromosomal block. These findings thus provide detailed insight into the evolution of complex polymorphisms involving different individual traits.
New Guinea highland wild dogs are the original New Guinea singing dogs
Authors: Surbakti Suriani , Parker Heidi G. , McIntyre James K. , Maury Hendra K. , Cairns Kylie M. , Selvig Meagan , Pangau-Adam Margaretha , Safonpo Apolo , Numberi Leonardo , Runtuboi Dirk Y. P. , Davis Brian W. , Ostrander Elaine A.
Published: September 2020

Significance

New Guinea singing dogs (NGSD) are distinctive among the Canidae because of their unique and characteristic vocalization, isolated habitat, and status as a rare representative of wild dogs. Their scarcity, combined with the knowledge that none have been captured or exported since the late 1970s, supports the hypothesis that NGSD are extinct in the wild. We have analyzed the nuclear genome of the first dogs captured from the highlands of Papua in approximately 50 y. We provide DNA-based evidence for an ancestral relationship between highland wild dogs (HWD) and captive NGSD suggesting that the founding population of the NGSD is not, in fact, extinct and that HWD should be resourced for conservation efforts to rebuild this unique canid population.
Analysis of β
2
AR-G
s
and β
2
AR-G
i
complex formation by NMR spectroscopy
Authors: Ma Xiuyan , Hu Yunfei , Batebi Hossein , Heng Jie , Xu Jun , Liu Xiangyu , Niu Xiaogang , Li Hongwei , Hildebrand Peter W. , Jin Changwen , Kobilka Brian K.
Published: September 2020

Significance

Recent structures of GPCRs in complex with G proteins provide important insights into G protein activation by family A and family B GPCRs; however, important questions remain. We don’t fully understand the mechanism of G protein coupling specificity or coupling promiscuity of some GPCRs. The β
2
AR preferentially couples to G
s
and less efficiently to G
i
, yet β
2
AR-G
i
coupling has been shown to play important roles in cardiac physiology. To better understand the structural basis for the preferential coupling of the β
2
AR to G
s
over G
i
, we used NMR spectroscopy and supporting MD simulations to study the conformational changes in the intracellular surface of the β
2
AR. These studies reveal a distinct difference in intracellular loop 2 interactions with G
s
and G
i1
.
Dynamic PB2-E627K substitution of influenza H7N9 virus indicates the in vivo genetic tuning and rapid host adaptation
Authors: Liu William J. , Li Jun , Zou Rongrong , Pan Jingcao , Jin Tao , Li Liqiang , Liu Peipei , Zhao Yingze , Yu Xinfen , Wang Haoqiu , Liu Guang , Jiang Hui , Bi Yuhai , Liu Lei , Yuen Kwok-Yung , Liu Yingxia , Gao George F.
Published: September 2020

Significance

Deep-sequencing of viral genomes based on original specimens from H7N9-infected patients and the surrounding poultry/environment has provided the first in-depth data on virus adaptation at the interface between poultry and humans. In contrast to the consistent dominance of 627E in poultry-derived H7N9, diverse but longitudinally changing ratios of the mammalian signature substitution PB2-E627K from patient specimens indicate a dynamic viral adaptation during infection, termed “genetic tuning” of avian influenza viruses in new hosts. Furthermore, the correlation between rapid host adaptation of H7N9 PB2-627 and the disease severity in patients is brought to light. Of note, under a one-health vision, our study provides direct big data evidence that “genetic tuning” of PB2-E627K is associated with H7N9 pathogenicity during human infection.
Rapid isothermal amplification and portable detection system for SARS-CoV-2
Authors: Ganguli Anurup , Mostafa Ariana , Berger Jacob , Aydin Mehmet Y. , Sun Fu , Ramirez Sarah A. Stewart de , Valera Enrique , Cunningham Brian T. , King William P. , Bashir Rashid
Published: September 2020

Significance

An important limitation of current assays for the detection of SARS-CoV-2 stems from their reliance on time-consuming, labor-intensive, and laboratory-based protocols for viral isolation, lysis, and removal of inhibiting materials. While RT-PCR remains the gold standard for performing clinical diagnostics to amplify the RNA sequences, there is an urgent need for alternative testing platforms that are rapid, accurate, simple, and portable. Here, we demonstrate isothermal RT-LAMP nucleic acid-based detection of SARS-CoV-2 with an additively manufactured cartridge and a smartphone-based instrument for testing that can be performed at the point of sample collection.
Resveratrol suppresses insulin-like growth factor I-induced osteoblast migration: attenuation of the p44/p42 MAP kinase pathway
Authors: Hioki Tomoyuki , Kawabata Tetsu , Sakai Go , Fujita Kazuhiko , Kuroyanagi Gen , Matsushima-Nishiwaki Rie , Kim Woo , Otsuka Takanobu , Iida Hiroki , Tokuda Haruhiko , Kozawa Osamu
Published: August 2020

Resveratrol is a natural polyphenol with beneficial antioxidant properties. It suppresses the migration of osteoblast-like MC3T3-E1 cells induced by epidermal growth factor, via SIRT1-mediated inhibition of SAPK/JNK and Akt. Moreover, insulin-like growth factor-I (IGF-I) stimulates the migration involving the pathways of p44/p42 mitogen-activated protein (MAP) kinase and Akt. Therefore, we investigated the effects of resveratrol on IGF-I-induced cell migration. Resveratrol and SRT1720, an activator of SIRT1, suppressed IGF-I-induced migration. Inauhzin, a SIRT1 inhibitor, significantly rescued the inhibition of IGF-I-induced cell migration by resveratrol. Resveratrol inhibited IGF-I-induced phosphorylation of p44/p42 MAP kinase but not Akt. SRT1720 inhibited IGF-I-induced phosphorylation of p44/p42 MAP kinase. Furthermore, PD98059, p44/p42 MAP kinase inhibitor, alone suppressed IGF-I-induced osteoblast migration, but did not affect the suppressive effect of resveratrol when administered concomitantly. These findings strongly suggest that resveratrol suppresses IGF-I-induced osteoblast migration via SIRT1 activation at least partially by attenuating the p44/p42 MAP kinase pathway.
Discovery of small-molecule modulator of heterotrimeric Gi-protein by integrated phenotypic profiling and chemical proteomics
Authors: Kawamura Tatsuro , Futamura Yushi , Shang Erchang , Muroi Makoto , Janning Petra , Ueno Masayoshi , Wilke Julian , Takeda Shigeki , Kondoh Yasumitsu , Ziegler Slava , Watanabe Nobumoto , Waldmann Herbert , Osada Hiroyuki
Published: September 2020

Discovery of small-molecule inducers of unique phenotypic changes combined with subsequent target identification often provides new insights into cellular functions. Here, we applied integrated profiling based on cellular morphological and proteomic changes to compound screening. We identified an indane derivative, NPD9055, which is mechanistically distinct from reference compounds with known modes of action. Employing a chemical proteomics approach, we then showed that NPD9055 binds subunits of heterotrimeric G-protein Gi. An in vitro [35S]GTPγS-binding assay revealed that NPD9055 inhibited GDP/GTP exchange on a Gαi subunit induced by a G-protein-coupled receptor agonist, but not on another G-protein from the Gαs family. In intact HeLa cells, NPD9055 induced an increase in intracellular Ca2+ levels and ERK/MAPK phosphorylation, both of which are regulated by Gβγ, following its dissociation from Gαi. Our observations suggest that NPD9055 targets Gαi and thus regulates Gβγ-dependent cellular processes, most likely by causing the dissociation of Gβγ from Gαi.
LGBT individuals and the struggle against Robert Mugabe’s extirpation in Zimbabwe
Authors: Muparamoto Nelson
Published: August 2020

Queer identities and non-heteronormative sexualities are increasingly becoming visible globally and Zimbabwe has witnessed an emergent queer mobilization and sexual identities politics. There have been significant attempts to expunge nonheterosexuals from Zimbabwean citizenry by drawing borders on the basis of sexual orientation. Over the years, western and local media have mediated a narrative of a thoroughly homophobic Zimbabwe, not the least emanating from the former president, Robert Mugabe’s homophobic utterances which recurrently generated global news stories. A dominant discourse framed homosexual identities as on or beyond the border of what is socially acceptable, whilst the individuals with queer identities have been denied legal protection and status. Predominantly, homophobic sentiments are expressed, often reflecting the view that homosexual identities should not be given space in Zimbabwe, nor should anything associated with it be tolerated. The populist arguments are based on among other things, depicting heterosexuality as ‘natural’, homosexuality as ‘uncultural’ and ‘unChristian’, and stereotyping gay people as licentious. Drawing on ethnographic research, this paper explores how LGBT people in Harare perceive, make sense of and cope with the infamous hate speech, ‘worse than dogs and pigs’, by the former president and the implications of this on their self-perception as they defiantly express a narrative of self-affirmation challenging the marginal status in popularized discourse.
Discernment in management and organizations
Authors: Miller Kent D.
Published: August 2020

Discernment integrates spiritual and religious values, wisdom, and sensibilities into decision making. What can spiritual and religious traditions of discernment contribute to management and organizations? A set of authors has responded to this question and offered initial empirical evidence. This article identifies and reviews research on discernment in management and organization studies, and clarifies the nature and location of discernment within the field. It also draws together writings on discernment from outside the field, organizes their coverage according to three units of analysis – processes, practices, and meetings – and elaborates the details of discernment within each. The literature review and conceptual development offered here sets the stage for further advances in discernment research and extending discernment in management and organizations.
Structural and electronic properties of Si- and Sn-doped (−201) β-Ga2O3 annealed in nitrogen and oxygen atmospheres
Authors: Tadjer Marko J , Freitas Jaime A , Culbertson James C , Weber Marc H , Glaser Evan R , Mock Alyssa L , Mahadik Nadeemullah A , Schmieder Kenneth , Jackson Eric , Gallagher James C , Feigelson Boris N , Kuramata Akito
Published: September 2020

Single crystal (−201) β-Ga2O3 substrates doped with Si and Sn have been thermally annealed in N2 and O2 atmospheres. Structural and electrical properties evaluation was performed via a number of experimental methods in order to quantify the effects of the doping and annealing ambient on the properties of these samples. All samples annealed in O2 exhibited significantly lower carrier concentration, as determined by capacitance–voltage measurements. Schottky barrier diodes exhibited excellent rectification when the Ga2O3 was annealed in N2, and significantly lower forward current using O2-annealed Ga2O3 substrates. Deep level transient spectroscopy revealed four deep trap levels with activation energies in the range of 0.40–1.07 eV. Electron spin resonance showed a decrease in shallow donor concentration, and cathodoluminescence spectroscopy revealed nearly two orders of magnitude lower emission intensity in O2-annealed Ga2O3 samples. Raman spectroscopy revealed a carrier concentration dependent Raman mode around 254 cm−1 observed only when the final anneal of (−201) β-Ga2O3 was not done in O2. Secondary ion mass spectroscopy measurements revealed diffusion of unintentional Fe towards the surface of the (−201) Ga2O3 samples after annealing in O2. Depth resolved positron annihilation spectroscopy showed an increased density of vacancy defects in the bulk region of O2-annealed Ga2O3 substrates.
Light-trapping structure based on ultra-thin GaAs solar cell
Authors: Peng Y S , Gong S F
Published: September 2020

It is well-known that the light-trapping effect is very important for improving cell efficiency and reducing material cost. Certain kinds of light-trapping schemes have been explored and applied to thin-film cells, especially to Si-based thin-film solar cells. This is considered less attractive in GaAs thin film cells, due to the fact that GaAs has a high absorption coefficient, a direct bandgap and suffers from strong surface recombination. In this paper, we describe the development of a highly efficient light-trapping structure utilizing periodically patterned front and back dielectric nanopyramid arrays keeping a completely flat GaAs active layer. It was found that our proposed structure was superior for ultra-thin active layers. The optimized structure yielded a photocurrent density of 20.94 mA cm−2 with an active layer thickness of 0.1 μm, which by far exceeded the reference cell photocurrent of 15.31 mA cm−2 with an equivalent thickness. These results are very significant for directing research into the light trapping and cost reduction of thin-film GaAs solar cells.
Refractive index of ZnO ultrathin films alternated with Al2O3 in multilayer heterostructures
Authors: López-Medina J , Carvalho William O F , Vazquez-Arce J , Moncada-Villa E , Oliveira Jr Osvaldo N , Farías M H , Tiznado H , Mejía-Salazar J R
Published: September 2020

The design of optoelectronic devices made with ZnO superlattices requires the knowledge of the refractive index, which currently can be done only for films thicker than 30 nm. In this work, we present an effective medium approach to determine the refractive index of ZnO layers as thin as 2 nm. The approach was implemented by determining the refractive index of ZnO layers ranging from 2 nm to 20 nm using spectroscopic ellipsometry measurements in multilayers. For a precise control of morphology and thickness, the superlattices were fabricated with atomic layer deposition (ALD) with alternating layers of 2 nm thick Al2O3 and ZnO, labeled as
N
ZnO-Al2O3, where N = 10, 20, 30, 50, 75 and 100. The total thickness of all superlattices was kept at 100 nm. The approach was validated by applying it to similar superlattices reported in the literature and fitting the transmittance spectra of the superlattices.
Preparation of porous Co-Pt alloys for catalytic synthesis of carbon nanofibers
Authors: Popov Anton A , Shubin Yury V , Bauman Yury I , Plyusnin Pavel E , Mishakov Ilya V , Sharafutdinov Marat R , Maksimovskiy Eugene A , Korenev Sergey V , Vedyagin Aleksey A
Published: September 2020

A simple and convenient procedure for the production of highly dispersed porous Co-Pt alloys to be used as catalysts for the synthesis of nanostructured carbon fibers (CNF) has been developed. The technique is based on the thermal decomposition of specially synthesized multicomponent precursors in a reducing atmosphere. A series of porous single-phase alloys Co-Pt (10–75 at% Pt) have been synthesized. The alloys containing 75 and 50 at% Pt were identified by the x-ray diffraction analysis as the intermetallics CoPt3 and CoPt, respectively. Within the region of 10–35 at% Pt, the synthesized alloys are represented by Co1−x
Pt
x
random solid solutions with face-centered cubic lattice. The alloys obtained are characterized by a porous structure consisting of assembled fragments with a size of 50–150 nm. The obtained alloys were tested in the catalytic chemical vapor deposition of the ethylene to CNF. A significant synergistic effect between Co and Pt in the synthesis of carbon nanomaterials (CNMs) was revealed. The yield of CNF (for 30 min reaction) for catalysts containing 25–35 at% Pt was 30–38 g(CNF)/g(cat), whereas those for Co (100%) and Pt (100%) samples were as low as 5.6 and >0.1 g(CNF)/g(cat), respectively. The produced CNM composed of fibers with a segmented structure was shown to be characterized by a rather high specific surface area (200–250 m2 g−1) and structural homogeneity.
Morphological characterization of diploid and triploidAcorus calamus(Acoraceae) from southern Western Siberia, parthenocarpy in sterile plants and occurrence of aneuploidy
Authors: Sokoloff Dmitry D , Skaptsov Mikhail V , Vislobokov Nikolay A , Smirnov Sergey V , Shmakov Alexander I , Remizowa Margarita V
Published: August 2020

Finding morphological differences between cytotypes that are stable throughout their geographical range is important for understanding evolution of polyploid complexes. The ancient monocot lineage Acorus includes two groups, of which A. calamus s.l., an important medicinal plant, is a polyploid complex with a centre of diversity in Asia. European plants are sterile triploids introduced by humans. An early study suggested that plants from temperate Asia are tetraploids, but subsequent work revealed diploids and triploids rather than tetraploids in Asiatic Russia; however, cytotype diversity in Western Siberia is insufficiently known. We document the occurrence of diploids and triploids in Western Siberia. Triploids that do not differ in genome size from European Acorus are abundant in the valley of the river Ob where the ability for extensive vegetative propagation provides ecological advantages. An isolated population of aneuploid triploids with 33 chromosomes is found outside the Ob valley. Flow cytometry provides an efficient tool for identification of aneuploid plants in Acorus. All triploids are sterile, but their flowers develop uniform parthenocarpic fruits. Fruits of diploids usually vary in size within a spadix depending on the number of developing seeds. In contrast to North America, where the native diploid plants differ from the introduced triploids by the absence of a secondary midrib of the ensiform leaf blade, Siberian diploids are similar to triploids in possessing a secondary midrib. We confirm that diploids differ from triploids in the size of air lacunae in leaves, which is determined by cell number rather than cell size in septa of aerenchyma. A combination of spathe width and spadix length measured after the male stage of anthesis shows different (slightly overlapping) patterns of variation between diploids and triploids in our material.
Takotsubo cardiomyopathy in COVID-19: a case report. Haemodynamic and therapeutic considerations
Authors: van Osch Dirk , Asselbergs Folkert W , Teske Arco J
Published: August 2020

Background

Cardiovascular complications are increasingly recognized during the current coronavirus disease 2019 (COVID-19) pandemic. Myocardial injury is most commonly described and its underlying mechanism is believed to be multifactorial. Next to Type 2 ischaemia, COVID-19 may lead to (peri)myocarditis or Takotsubo (or stress) cardiomyopathy.

Case summary

A 72-year-old woman was admitted to the intensive care unit for mechanical ventilation because of respiratory insufficiency secondary to COVID-19 viral pneumonia. Seven days after admission, she developed new negative T-waves and a prolonged QTc interval on electrocardiography (ECG). Troponin levels were mildly elevated. Echocardiography showed a poor left ventricular systolic function with apical ballooning consistent with the diagnosis Takotsubo cardiomyopathy. Seven days afterwards, the ECG and troponin levels normalized. Echocardiography showed improvement of left ventricular systolic function, however with persistent hypokinesia of the apical segments. Coronary artery disease was excluded using coronary computed tomography angiography. The patient was discharged home and follow-up echocardiography after 3 months showed normal contractility of the apical myocardial segments, with normalization of the left ventricular systolic function, as expected in Takotsubo cardiomyopathy.

Discussion

COVID-19 caregivers should be aware of Takotsubo cardiomyopathy as complication of COVID-19, since regular use of QT-prolonging drugs combined with prolongation of the QTc interval in Takotsubo cardiomyopathy may lead to life-threatening arrhythmias. Furthermore, Takotsubo cardiomyopathy may lead to acute heart failure and even cardiogenic shock. Frequent ECG monitoring of COVID-19 patients therefore is of paramount importance and timely echocardiography should be obtained when ECG abnormalities or haemodynamical problems occur.