bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative morphometric analysis of single gold nanoparticles by optical extinction microscopy: Material permittivity and surface damping effects
Authors: Payne Lukas M. , Masia Francesco , Zilli Attilio , Albrecht Wiebke , Borri Paola , Langbein Wolfgang
Published: January 2021

Quantifying the optical extinction cross section of a plasmonic nanoparticle has recently emerged as a powerful means to characterize the nanoparticle morphologically, i.e., to determine its size and shape with a precision comparable to electron microscopy while using a simple optical microscope. In this context, a critical piece of information to solve the inverse problem, namely, calculating the particle geometry from the measured cross section, is the material permittivity. For bulk gold, many datasets have been reported in the literature, raising the question of which one is more adequate to describe specific systems at the nanoscale. Another question is how the nanoparticle interface, not present in the bulk material, affects its permittivity. In this work, we have investigated the role of the material permittivities on the morphometric characterization of defect-free ultra-uniform gold nanospheres with diameters of 10 nm and 30 nm, following a quantitative analysis of the polarization- and spectrally-resolved extinction cross section on hundreds of individual nanoparticles. The measured cross sections were fitted using an ellipsoid model. By minimizing the fit error or the variation of the fitted dimensions with color channel selection, the material permittivity dataset and the surface damping parameter g best describing the nanoparticles are found to be the single crystal dataset by Olmon et al. [Phys. Rev. B 86, 235147 (2012)] and g ≈ 1, respectively. The resulting nanoparticle geometries are in good agreement with transmission electron microscopy of the same sample batches, including both 2D projection and tomography.
Four-probe sensing of temperature during Joule heating of silicon
Authors: Pedersen Asger Kjærgård , Madhi Daena , Mirosnikov Daniil , Jepsen Peter Uhd , Petersen Dirch Hjorth
Published: January 2021

We present a four-probe setup for measuring temperature of Joule-heated silicon in two independent ways from the same voltage measurement: a method using the thermal dependence of resistivity and a method based on the measured sheet power density. The two methods are compared to optical temperature measurements made by fitting a gray-body model onto data from a commercial spectrometer. The two four-probe temperature measurements are conducted from 890 K to 1540 K, and they converge at temperatures above 1400 K indicating a high degree of self-consistency.
Magnetocrystalline anisotropy correlated negative anisotropic magnetoresistance in epitaxial Fe30Co70 thin films
Authors: Miao Yu , Yang Dezheng , Jia Lei , Li Xiaolin , Yang Shuanglong , Gao Cunxu , Xue Desheng
Published: January 2021

We report on the magnetoresistance in different crystallographic directions of epitaxial ferromagnetic Fe30Co70 thin films with magnetization rotated in the film plane. A negative single crystal anisotropic magnetoresistance (SCAMR) is found when the current is along the easy magnetization axis [110], and the SCAMR can be tuned to the conventional positive one when the current flows along the hard magnetization axis [100]. This finding is explained comprehensively by a magnetocrystalline anisotropy (MCA) symmetry-adapted model expanded along the easy magnetization direction, with which the SCAMR can be represented as a MCA-independent conventional term cos 2φM and a series of MCA-dependent terms cos 2nφA (n≥1). The results show that the MCA-dependent twofold term contributes to the negative SCAMR, which cannot be used as a fingerprint of the half-metallicity. Our finding provides an approach to understand and design the magnetoresistance with ferromagnets by MCA.
Characterizations of electronic and optical properties of Sb-based phase-change material stabilized by alloying Cr
Authors: Chen Chao , Lin Jun , Mai Xianliang , Qiao Chong , Tong Hao , Cheng Xiaomin , Wang Songyou , Wang Cai-Zhuang , Ho Kai-Ming , Xu Ming , Miao Xiangshui
Published: January 2021

The application of monatomic Sb material in the phase-change memory has been greatly compromised due to easy crystallization at room temperature. In this work, we alloy 10 at. % Cr into Sb, so that the crystallization temperature of the amorphous Cr10Sb90 thin film has been raised to above 130 °C and the crystallinity can be controlled by different annealing temperatures. We find that Cr10Sb90 thin films possess relatively large electrical and optical contrasts between the amorphous (a-) and crystalline (c-) states, e.g., the resistance of the a-film decreases by three orders of magnitude after crystallization and the real part of the dielectric function of glass is much larger than that of the crystal in the wavelength range of 300 to 1650 nm. The first-principles simulations reveal that Cr doping leads to a more disordered a-state and the Cr–Sb bonds appear to be stronger than Sb–Sb bonds, which explains the enhanced stability of a-Cr10Sb90. Our findings demonstrate that alloying with Cr is an effective way to improve the stability of phase-change materials in the memory applications without damaging the desired properties of these materials.
Tunable spin–orbit torque efficiency in in-plane and perpendicular magnetized [Pt/Co]n multilayer
Authors: Xue Fen , Lin Shy-Jay , DC Mahendra , Bi Chong , Li Xiang , Tsai Wilman , Wang Shan X.
Published: January 2021

Despite the great promise for very efficient and fast switching of magnetization in embedded memory and computing applications, the performance of spin–orbit torque (SOT) lags behind conventional technologies due to the low spin-Hall conductivity of the spin Hall materials. This work reports an advantageous spin Hall material, periodic [Pt/Co]n multilayer, which combines a low resistivity with a widely tunable spin Hall effect along with magnetization as evidenced with an in-plane CoFeB ferromagnetic detector. Three detection methods have been employed to illustrate the trends of magnetic orientation, interlayer exchange coupling, spin transport, and SOT efficiency as a function of Co thickness, which casts insight into the mechanisms of the SOTs in the [Pt/Co]n multilayer. With the varying Co thickness in the [Pt/Co]n multilayer, it is found that the damping-like torque efficiency is negative and the field-like torque efficiency is 8.2–31.5 times larger. The [Pt/Co]n multilayers have two spin reorientation transition states where the spin Hall angle θSH is maximized with a low resistivity of ∼ 40 μΩ cm, at tCo = 0.507 nm and 0.159 nm. We simulated the magnetization trajectories and time-domain responses of SOT switching with a current pulse and demonstrated a much faster switching in the spin reorientation transition states based on the coupled Landau–Lifshitz–Gilbert equation.
Investigation into the mechanism and dynamics of DNA association and dissociation utilizing kinetic Monte Carlo simulations
Authors: Menssen Ryan J. , Kimmel Gregory J. , Tokmakoff Andrei
Published: January 2021

In this work, we present a kinetic Markov state Monte Carlo model designed to complement temperature-jump (T-jump) infrared spectroscopy experiments probing the kinetics and dynamics of short DNA oligonucleotides. The model is designed to be accessible to experimental researchers in terms of both computational simplicity and expense while providing detailed insights beyond those provided by experimental methods. The model is an extension of a thermodynamic lattice model for DNA hybridization utilizing the formalism of the nucleation-zipper mechanism. Association and dissociation trajectories were generated utilizing the Gillespie algorithm and parameters determined via fitting the association and dissociation timescales to previously published experimental data. Terminal end fraying, experimentally observed following a rapid T-jump, in the sequence 5′-ATATGCATAT-3′ was replicated by the model that also demonstrated that experimentally observed fast dynamics in the sequences 5′-C(AT)nG-3′, where n = 2–6, were also due to terminal end fraying. The dominant association pathways, isolated by transition pathway theory, showed two primary motifs: initiating at or next to a G:C base pair, which is enthalpically favorable and related to the increased strength of G:C base pairs, and initiating in the center of the sequence, which is entropically favorable and related to minimizing the penalty associated with the decrease in configurational entropy due to hybridization.
Interfacial chemical states and recoverable spin pumping in YIG/Pt
Authors: Li Mingming , Zhang Dainan , Jin Lichuan , Liu Bo , Zhong Zhiyong , Tang Xiaoli , Meng Hao , Yang Qinghui , Zhang Lei , Zhang Huaiwu
Published: January 2021

Ion etching is an essential step in the processing of spintronic devices. In this work, we investigated the role of argon ion (Ar+) bombardment in the spin pumping and inverse spin Hall effect in the Y3Fe5O12/Pt (YIG/Pt) heterostructure. The inverse spin Hall voltage is found to reduce by an order of two when the argon ion bombardment is employed on the YIG surface before the deposition of the Pt layer. This giant inhibition of spin injection efficiency is undesirable. In this work, we propose an experimental technique for its recovery via a chemical route. The interface property and chemical state were identified by transmission electron microscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. We found that the argon ion bombardment on the YIG surface leads to an increase in the ratio of Fe2+ ions in the YIG/Pt interface region. Moreover, the interface magnetic moment reduces in the presence of Fe2+ ions, which resulted in the decrease in spin injection efficiency. A strong oxidizing solution (a mixture of concentrated H2SO4 and 30% H2O2 of 1:1 volume ratio) was used to recover the valence of iron and subsequently the interface magnetic moment. Our results are helpful for the understanding of the importance of interface properties and the optimization of spintronic device processing technology.
Magneto-elastic coupling in multiferroic metal-organic framework [(CH3)2NH2]Co(HCOO)3
Authors: Thirunavukkuarasu Komalavalli , Richardson Rachael , Lu Zhengguang , Smirnov Dmitry , Huang Nan , Combs Nicholas , Pokharel Ganesh , Mandrus David
Published: January 2021

Metal-organic frameworks based on metal-formates have emerged as a intriguing class of multiferroics with wide range of applications. In this work, we present magneto-Raman spectroscopic investigations on [(CH3)2NH2]Co(HCOO)3 belonging to this family. The spectroscopic studies were performed at magnetic fields up to 31 T at the temperature of 2.3 K. It was observed that the formate bending mode at around 798 cm−1 shifts to higher energies with increasing magnetic field. The magneto-response of the phonon also exhibits anomalies at magnetic fields of 14.5 T and 23.5 T corresponding to magnetic phase transitions. Based on our results, we conclude that the formate bending mode does play a role in facilitating the saturation of magnetic states similar to its Mn and Ni analogs.
Study on the acid-base balance in blood under pulsed magnetic field using magnetic beads
Authors: Bang Seunghwan , Lee Hyunsook
Published: January 2021

The blood’s acid-base balance is precisely controlled because even a minor deviation from the normal range can severely affect many organs. Due to the Warburg effect, in tumor cells, an imbalance between oxygen supply and consumption and the accumulation of lactate cause an increasing concentration of H+. As a consequence, intracellular pH decreases, resulting in acidity. Since the pulsed magnetic field (PMF) influences human physiology, many studies have reported its effect on anti-nociception as well as its improvement of blood circulation. Our study has tried to investigate the influence of PMF on blood's acid-base balance. In addition, the applicability of PMF to H+ pump inhibitor in tumor cells was evaluated using negatively-charged magnetic beads (MB). Tert-butyl hydroperoxide (tBHP) was used to oxidizing agents, in order to make an acidic environment similar to that in tumor cells. Our PMF stimulator has the maximum intensity of 0.27T at a transition time of 102 μs with pulse intervals of 1Hz. The changes in the pH of blood and the number of red blood cells (RBCs) attached to MB were examined before and after PMF stimulus. The blood treated with tBHP on RBC is more acidic than normal blood, but it was observed that the pH is restored after PMF stimulus. Also, it was confirmed that MB adheres more to the RBCs after PMF stimulus, which could indicate that PMF stimulus not only increases the zeta potential, but also reduces the H+ in the blood by combining MB with plasma cations. Further study is needed to optimize PMF stimulation conditions such as pulse shape, duration, or repetition rate for fast homeostasis recovery in acid-base unbalanced blood.
Magnetocrystalline anisotropy of α″–Fe16N2 under various DFT approaches
Authors: Stoeckl Peter , Swatek Przemyslaw , Wang Jian-Ping
Published: January 2021

The magnetocrystalline anisotropy (MCA) energy of the giant saturation magnetization candidate material α″–Fe16N2 was investigated using first-principles electronic-structure calculations. The plane-wave density-functional theory (DFT) code Quantum ESPRESSO was employed to study the effect of different DFT approaches on the system, particularly the influence of exchange-correlation functionals and pseudopotential methods. The MCA energies obtained this way are within the range of previous theoretical and experimental results, while exhibiting significant variation between the different approaches. The role and limitations of these approaches in the view of Fe16N2 band structure are discussed in detail.
Single-cell atlas of developing murine adrenal gland reveals relation of Schwann cell precursor signature to neuroblastoma phenotype
Authors: Hanemaaijer Evelyn S. , Margaritis Thanasis , Sanders Karin , Bos Frank L. , Candelli Tito , Al-Saati Hanin , van Noesel Max M. , Meyer-Wentrup Friederike A. G. , van de Wetering Marc , Holstege Frank C. P. , Clevers Hans
Published: January 2021

Significance

Neuroblastoma is a childhood malignancy that originates from neural crest cells. We present a single-cell transcriptome and localization atlas of the developing adrenal gland and identify seven different cell clusters that make up the adrenal medulla. Their transcriptomic profiles were used to generate gene signatures that were compared to neuroblastoma samples. The neural crest-derived “SCP” gene signature score anticorrelates with disease severity based on staging and poor prognosis (molecular) markers, while a high score was associated with higher overall survival rates.
Caveolin-1 and cavin1 act synergistically to generate a unique lipid environment in caveolae
Authors: Zhou Yong , Ariotti Nicholas , Rae James , Liang Hong , Tillu Vikas , Tee Shern , Bastiani Michele , Bademosi Adekunle T. , Collins Brett M. , Meunier Frederic A. , Hancock John F. , Parton Robert G.
Published: January 2021

Caveolae are specialized domains of the vertebrate cell surface with a well-defined morphology and crucial roles in cell migration and mechanoprotection. Unique compositions of proteins and lipids determine membrane architectures. The precise caveolar lipid profile and the roles of the major caveolar structural proteins, caveolins and cavins, in selectively sorting lipids have not been defined. Here, we used quantitative nanoscale lipid mapping together with molecular dynamic simulations to define the caveolar lipid profile. We show that caveolin-1 (CAV1) and cavin1 individually sort distinct plasma membrane lipids. Intact caveolar structures composed of both CAV1 and cavin1 further generate a unique lipid nano-environment. The caveolar lipid sorting capability includes selectivities for lipid headgroups and acyl chains. Because lipid headgroup metabolism and acyl chain remodeling are tightly regulated, this selective lipid sorting may allow caveolae to act as transit hubs to direct communications among lipid metabolism, vesicular trafficking, and signaling.
Molecular organization of cytokinesis node predicts the constriction rate of the contractile ring
Authors: Bellingham-Johnstun Kimberly , Anders Erica Casey , Ravi John , Bruinsma Christina , Laplante Caroline
Published: January 2021

The molecular organization of cytokinesis proteins governs contractile ring function. We used single molecule localization microscopy in live cells to elucidate the molecular organization of cytokinesis proteins and relate it to the constriction rate of the contractile ring. Wild-type fission yeast cells assemble contractile rings by the coalescence of cortical proteins complexes called nodes whereas cells without Anillin/Mid1p (Δmid1) lack visible nodes yet assemble contractile rings competent for constriction from the looping of strands. We leveraged the Δmid1 contractile ring assembly mechanism to determine how two distinct molecular organizations, nodes versus strands, can yield functional contractile rings. Contrary to previous interpretations, nodes assemble in Δmid1 cells. Our results suggest that Myo2p heads condense upon interaction with actin filaments and an excess number of Myo2p heads bound to actin filaments hinders constriction thus reducing the constriction rate. Our work establishes a predictive correlation between the molecular organization of nodes and the behavior of the contractile ring.
Suppression of local type I interferon by gut microbiota–derived butyrate impairs antitumor effects of ionizing radiation
Authors: Yang Kaiting , Hou Yuzhu , Zhang Yuan , Liang Hua , Sharma Anukriti , Zheng Wenxin , Wang Liangliang , Torres Rolando , Tatebe Ken , Chmura Steven J. , Pitroda Sean P. , Gilbert Jack A. , Fu Yang-Xin , Weichselbaum Ralph R.
Published: January 2021

The antitumor effects of ionizing radiation (IR) are mediated in part through activation of innate and adaptive immunity. Here we report that gut microbiota influences tumor control following IR. Vancomycin decreased the abundance of butyrate-producing gut bacteria and enhanced antitumor responses to IR. Oral administration of Lachnospiraceae, a family of vancomycin-sensitive bacteria, was associated with increased systemic and intratumoral butyric acid levels and impaired the efficacy of IR in germ-free (GF) mice. Local butyrate inhibited STING-activated type I IFN expression in dendritic cells (DCs) through blockade of TBK1 and IRF3 phosphorylation, which abrogated IR-induced tumor-specific cytotoxic T cell immune responses without directly protecting tumor cells from radiation. Our findings demonstrate that the selective targeting of butyrate-producing microbiota may provide a novel therapeutic option to enhance tumor radiation sensitivity.
A comment on no-force conditions for black holes and branes
Authors: Van Riet Thomas
Published: January 2021

In the context of the weak gravity conjecture the notion of quasi-extremality for black holes and branes was recently defined as the property of having either vanishing horizon size or surface gravity. It was derived that such objects obey a no-force condition. In this short note I present a simplified derivation that is essentially present in the formalism of timelike reduction pioneered by Breitenlohner, Gibbons and Maison. This formalism also provides the natural definition of quasi-extremality for gravitational instantons (and wormholes) sourced by axion fluxes and strengthens the argument that macroscopic axion wormholes do not contribute in the path integral since they are self-repulsive in a Euclidean sense.
Cocktail of reactive species generated by cold atmospheric plasma: oral administration induces non-small cell lung cancer cell death
Authors: Song Chang-Hyun , Attri Pankaj , Ku Sae-Kwang , Han Ihn , Bogaerts Annemie , Choi Eun Ha
Published: January 2021

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, with 85% of all lung cancer reported as NSCLC. Moreover, there are no effective treatments in advanced NSCLC. This study shows for the first time that oral administration of plasma-treated water (PTW) can cure advanced NSCLC. The cold plasma in water generates a cocktail of reactive species, and oral administration of this cocktail to mice showed no toxicities even at the highest dose of PTW, after a single dose and repeated doses for 28 d in mice.In vivostudies reveal that PTW showed favorable anticancer effects on chemo-resistant lung cancer, similarly to gefitinib treatment as a reference drug in a chemo-resistant NSCLC model. The anticancer activities of PTW seem to be involved in inhibiting proliferation and angiogenesis and enhancing apoptosis in the cancer cells. Interestingly, the PTW contributes to enhanced immune response and improved cachexia in the model.
Estimated solar-neutrino capture rates of 131Xe: implications for multi-tonne Xe-based experiments
Authors: Kostensalo J , Suhonen J , Zuber K
Published: January 2021

Various large-scale experiments for double beta decay or dark matter are based on xenon. Current experiments are on the tonne scale, but future ideas also aim for even larger sizes. Here we study the potential of the isotope 131Xe to allow real-time capture measurements of solar pp-chain neutrinos, besides classical neutrino-electron scattering. Here we use improved nuclear-structure calculations to determine the cross sections of solar neutrinos on 131Xe. Our updated capture-rate estimate is (80 ± 22) SNU, with neutrino survival probabilities taken into account. According to our calculations, the 8B neutrinos are the dominant contribution to the total capture rate. Due to our more accurate treatment of the phase-space factor the computed capture rate, (60 ± 19) SNU, is significantly larger than what was expected based on previous calculations. This improves considerably the prospects of real-time monitoring of pp-chain neutrinos for long periods of time.
Anisotropic magnetotransport in tilted magnetic topological semimetals
Authors: Wu J , Wang C M
Published: January 2021

We systematically investigate the anisotropic magneto-conductivity and planar Hall effect in tilted magnetic topological semimetals in the frame of Kubo formula by considering the vertex correction of velocity. The nonzero anisotropic magneto-conductivity is due to the intrinsic magnetization by magnetic doping rather than the external magnetic field previously studied in literatures. In the scenario, tilt, which is common in band structure, plays a key role in this anisotropic magneto-conductivity. This anisotropic magneto-conductivity completely originates from the band anisotropy. The vertex correction only amends the magnitude, but does not change the qualitative behavior of the longitudinal conductivity. However, the planar Hall conductivity is always zero for tilt along both x and y directions in vivid contrast to the case arising from an external magnetic field. Our work offers a route to understand the anisotropic magneto-conductivity effect in tilted Weyl semimetals with Zeeman field. It will be helpful to get a deeper understanding of the transport characteristic in tilted topological semimetals.
Growth, electronic structure and superconductivity of ultrathin epitaxial CoSi2 films
Authors: Fang Yuan , Wang Ding , Li Peng , Su Hang , Le Tian , Wu Yi , Yang Guo-Wei , Zhang Hua-Li , Xiao Zhi-Guang , Sun Yan-Qiu , Hong Si-Yuan , Xie Yan-Wu , Wang Huan-Hua , Cao Chao , Lu Xin , Yuan Hui-Qiu , Liu Yang
Published: January 2021

We report growth, electronic structure and superconductivity of ultrathin epitaxial CoSi2 films on Si (111). At low coverages, preferred islands with 2, 5 and 6 monolayers height develop, which agrees well with the surface energy calculation. We observe clear quantum well states as a result of electronic confinement and their dispersion agrees well with density functional theory calculations, indicating weak correlation effect despite strong contributions from Co 3d electrons. Ex situ transport measurements show that superconductivity persists down to at least 10 monolayers, with reduced T
c but largely enhanced upper critical field. Our study opens up the opportunity to study the interplay between quantum confinement, interfacial symmetry breaking and superconductivity in an epitaxial silicide film, which is technologically relevant in microelectronics.
Ab initio study of electronic and magnetic properties of Mn2RuZ/MgO (001) heterojunctions (Z
= Al, Ge)
Authors: Roy Tufan , Tsujikawa Masahito , Shirai Masafumi
Published: January 2021

We studied the applicability of Heusler alloys Mn2RuZ (Z = Al, Ga, Ge, Si) to the electrode materials of MgO-based magnetic tunnel junctions. All these alloys possess Hg2CuTi-type inverse Heusler alloy structure and ferrimagnetic ground state. Our study reveals the half-metallic electronic structure with highly spin-polarized Δ1 band, which is robust against atomic disorder. Next we studied the electronic structure of Mn2RuAl/MgO and Mn2RuGe/MgO heterojunctions. We found that the MnAl- or MnGe-terminated interface is energetically more favorable compared to the MnRu-terminated interface. Interfacial states appear at the Fermi level in the minority-spin gap for the Mn2RuGe/MgO junction. We discuss the origin of these interfacial states in terms of local environment around each constituent atom. On the other hand, in the Mn2RuAl/MgO junction, high spin polarization of bulk Mn2RuAl is preserved independent of its termination.
A new prescription to achieve a high degree of spin polarization in a spin–orbit coupled quantum ring: efficient engineering by irradiation
Authors: Ganguly Sudin , Maiti Santanu K
Published: January 2021

The present work discusses the possibility to achieve a high degree of spin polarization in a three-terminal quantum system. Irradiating the system, subjected to Rashba spin–orbit (SO) interaction, we find high degree of spin polarization under a suitable input condition along with different magnitudes and phases at the two output leads. The system is described within a tight-binding (TB) framework and the effect of irradiation is incorporated following the Floquet–Bloch (FB) ansatz. All the spin-dependent transmission probabilities are evaluated through Green’s function technique using Landauer–Büttiker formalism. Several possible aspects are included to make the system more realistic and examined rigorously in the present work. To name a few, the effects of irradiation, SO interaction, interface sensitivity, system size, system temperature are investigated, and finally, the role of correlated impurities are studied. Despite having numerous proposals available to generate and manipulate spin-selective transmissions, such a prescription exploiting the irradiation effect is relatively new to the best of our concern.
Floquet–Dirac fermions in monolayer graphene by Wannier functions
Authors: Liu Jian , Hou Wenjie , Sun Lei , Ma Xikui , Feng Xukun , Nie Tianxiao , Zhao Mingwen
Published: January 2021

Wannier functions have been widely applied in the study of topological properties and Floquet–Bloch bands of materials. Usually, the real-space Wannier functions are linked to the k-space Hamiltonian by two types of Fourier transform (FT), namely lattice-gauge FT (LGFT) and atomic-gauge FT (AGFT), but the differences between these two FTs on Floquet–Bloch bands have rarely been addressed. Taking monolayer graphene as an example, we demonstrate that LGFT gives different topological descriptions on the Floquet–Bloch bands for the structurally equivalent directions which are obviously unphysical, while AGFT is immune to this dilemma. We introduce the atomic-laser periodic effect to explain the different Floquet–Bloch bands between the LGFT and AGFT. Using AGFT, we showed that linearly polarized laser could effectively manipulate the properties of the Dirac fermions in graphene, such as the location, generation and annihilation of Dirac points. This proposal offers not only deeper understanding on the role of Wannier functions in solving the Floquet systems, but also a promising platform to study the interaction between the time-periodic laser field and materials.
Particle size distribution measurement in a flowing aerosol using dynamic light scattering
Authors: Mu Tongtong , Shen Jin , Wang Mengjie , Thomas John C , Zhu Xinjun , Yuan Xi , Liu Wei , Sun Xianming , Wang Yajing , Han Jinzhuang , Liu Zhenming
Published: January 2021

Simulated and experimental data were used to investigate the particle size distribution (PSD) recovery from a flowing aerosol via dynamic light scattering (DLS). It is found that, for a unimodal PSD, increasing the flow velocity leads to an increase in the error of the peak position, a decrease in the peak height and a broadening of the PSD. This is exacerbated for larger aerosol particles. For a bimodal PSD, the separation of the two peaks decreases and results in a single-peak PSD as the velocity increases. The effect of velocity on the measurement is similar to adding signal noise, which increases with the velocity. This effect is related to the measured aerosol particle size. The larger the particles, the lower the signal-to-noise ratio. By comparing DLS measurement results for flowing and non-flowing aerosol samples, it is possible to determine the maximum flow rate at which measurements can be usefully made.
Interaction of hydrogen-edged boron nitride flakes with lithium: boron nitride as a protecting layer for a lithium-ion battery and a spin-dependent photon emission device
Authors: Kheirabadi Narjes , Shafiekhani Azizollah
Published: January 2021

The current rechargeable battery technologies have a failure in their performance at high pressure and temperature. In this article, we have brought theoretical insights on using boron nitride flakes as a protecting layer for a lithium-ion battery device and extended its application for a spin-dependent photon emission device. Hence, the electronic properties of pristine and lithium-doped hydrogen-edged boron nitride flakes have been studied by the first principle density functional theory calculations. In this study, we have discussed the stability, adsorption energies, bond lengths, electronic gaps, frontier molecular orbitals, the density of states, charge distributions, and dipole moments of pristine and lithium hydrogen-edged doped boron nitride flakes.
Metal artifact reduction method based on a constrained beam-hardening estimator for polychromatic x-ray CT
Authors: Hur Jin , Kim Dongjoon , Shin Yeong-Gil , Lee Ho
Published: January 2021

Beam hardening in x-ray computed tomography (CT) is inevitable because of the polychromatic x-ray spectrum and energy-dependent attenuation coefficients of materials, leading to the underestimation of artifacts arising from projection data, especially on metal regions. State-of-the-art research on beam-hardening artifacts is based on a numerical method that recursively performs CT reconstruction, which leads to a heavy computational burden. To address this computational issue, we propose a constrained beam-hardening estimator that provides an efficient numerical solution via a linear combination of two images reconstructed only once during the entire process. The proposed estimator reflects the geometry of metal objects and physical characteristics of beam hardening during the transmission of polychromatic x-rays through a material. Most of the associated parameters are numerically obtained from an initial uncorrected CT image and forward projection transformation without additional optimization procedures. Only the unknown parameter related to beam-hardening artifacts is fine-tuned by linear optimization, which is performed only in the reconstruction image domain. The proposed approach was systematically assessed using numerical simulations and phantom data for qualitative and quantitative comparisons. Compared with existing sinogram inpainting-based and model-based approaches, the proposed scheme in conjunction with the constrained beam-hardening estimator not only provided improved image quality in areas surrounding the metal but also achieved fast beam-hardening correction owing to the analytical reconstruction structure. This work may have significant implications in improving dose calculation accuracy or target volume delineation for treatment planning in radiotherapy.
Further investigations of a radiation detector based on ionization-induced modulation of optical polarization
Authors: Wang Yuli , Tao Li , Abbaszadeh Shiva , Levin Craig
Published: January 2021

Optical property modulation induced by ionizing radiation is a promising approach for ultra-fast, lower time jitter detection of photon arrival time. If successful, this method can be utilized in time-of-flight positron emission tomography to achieve a coincidence time resolution approaching 10 ps. In this work, the optical property modulation based method is further developed with focus on a detection setup based on two crossed polarizers. Previous work demonstrated that such an optical setup could be utilized in radiation detection, though its detection sensitivity needed improvement. This work investigates the angle between polarizers and electric field distribution within the detection crystal to understand and improve the detection sensitivity of an optical polarization modulation based method. For this work, cadmium telluride (CdTe) was studied as the detector crystal . The ‘magic’ angle (i.e. optimal working angle) of the two crossed polarizers based optical setup with CdTe were explored theoretically and experimentally. The experimental results show that the detection sensitivity could be improved by around 10% by determining the appropriate ‘magic’ angle. We then studied the dependence of detection sensitivity on electric field distribution as well as on the bias voltage across the detector crystal using CdTe crystals. The experimental results show that a smaller electrode on the detector crystal, or a more concentrated electric field distribution could improve detection sensitivity. For CdTe, a detector crystal sample with 2.5 mm × 2.5 mm square electrode has twice the detection sensitivity of a detector crystal with 5 mm × 5 mm square electrode. Increasing the bias voltage before saturation for CdTe could further enhance the modulation strength and thus, the sensitivity. Our investigations demonstrated that by determining the proper working angle of polarizers and bias electrical distribution to the detector, we could improve the sensitivity of the proposed optical setup.
Quantitative investigation of dose accumulation errors from intra-fraction motion in MRgRT for prostate cancer
Authors: Bosma L S , Zachiu C , Ries M , Denis de Senneville B , Raaymakers B W
Published: January 2021

Accurate spatial dose delivery in radiotherapy is frequently complicated due to changes in the patient’s internal anatomy during and in-between therapy segments. The recent introduction of hybrid MRI radiotherapy systems allows unequaled soft-tissue visualization during radiation delivery and can be used for dose reconstruction to quantify the impact of motion. To this end, knowledge of anatomical deformations obtained from continuous monitoring during treatment has to be combined with information on the spatio-temporal dose delivery to perform motion-compensated dose accumulation (MCDA). Here, the influence of the choice of deformable image registration algorithm, dose warping strategy, and magnetic resonance image resolution and signal-to-noise-ratio on the resulting MCDA is investigated. For a quantitative investigation, four 4D MRI-datasets representing typical patient observed motion patterns are generated using finite element modeling and serve as a gold standard. Energy delivery is simulated intra-fractionally in the deformed image space and, subsequently, MCDA-processed. Finally, the results are substantiated by comparing MCDA strategies on clinically acquired patient data. It is shown that MCDA is needed for correct quantitative dose reconstruction. For prostate treatments, using the energy per mass transfer dose warping strategy has the largest influence on decreasing dose estimation errors.
An SECE array of piezoelectric energy harvesting
Authors: Wu P H , Lin J T , Lo Y C , Shu Y C
Published: January 2021

The paper studies the electrical response of an array of piezoelectric oscillators attached to the synchronized electric charge extraction (SECE) interface circuit. The analytic estimate of output power is derived and presented through the matrix formulation of generalized Ohm’s law (charging on capacitance) for the case of parallel (series) connection of energy harvesters. These formulations mainly depend on the proposed equivalent load impedances which are independent of external resistive loads. It therefore offers an advantage of enabling harvested power independent of DC output voltage and making the harvester array desirable for broadband energy scavenging. The proposed framework is subsequently validated both numerically and experimentally. The results show that the power output and bandwidth of an SECE-based array are superior to that based on the standard energy harvesting circuit. Further, it is found that the behavior of an SECE array electrically arranged in parallel connection is different from that connected in series. The former demonstrates the output power higher than the latter, while the latter exhibits roughly uniform peak power in frequency response. However, the experiment indicates the unexpected power drop deviated significantly from the prediction in the array of harvesters connected in series. Such a discrepancy is explained as a result of comparatively serious leakage current in the reverse-biased diodes.
Non-classicalities exhibited by the superposition of Schrödinger’s cat state with the vacuum of the optical field
Authors: Mishra Karunesh Kumar , Yadav Dhiraj , Shukla Gaurav , Mishra Devendra Kumar
Published: January 2021

Superposition of two coherent states, the Schrodinger’s cat state, can exhibit different nonclassical properties having foundational applications in quantum information processing. We consider the ‘superposition of Schrodinger’s cat state with the vacuum state (SCVS)’ of the optical field. We discuss different witness of nonclassicality properties such as lower- and higher-order squeezing (viz., squeezing, Hong & Mandel’s fourth-order squeezing, amplitude-squared squeezing) and sub-Poissonian photon statistics. Further, we discuss the negativity of the Wigner function of SCVS indicating the nonclassicality of the state under investigation. We find that the vacuum state contribution in SCVS exhibits different nonclassicalities under some conditions stronger where the nonclassicalities exhibited by the state without vacuum state contribution are weaker.
A Small Actively Controlled High-resolution Spectrograph Based on Off-the-shelf Components
Authors: Jones H. R. A. , Martin W. E. , Anglada-Escudé G. , Errmann R. , Campbell D. A. , Baker C. , Boonsri C. , Choochalerm P.
Published: January 2021

We present the design and testing of a prototype in-plane echelle spectrograph based on an actively controlled fiber-fed double-pass design. This system aims to be small and efficient with the minimum number of optical surfaces—currently a collimator/camera lens, cross-dispersing prism, grating and a reflector to send light to the detector. It is built from catalog optical components and has dimensions of approximately 20 × 30 cm. It works in the optical regime with a resolution of >70,000. The spectrograph is fed by a bifurcated fiber with one fiber to a telescope and the other used to provide simultaneous Thorium Argon light illumination for wavelength calibration. The positions of the arc lines on the detector are processed in real time and commercial auto-guiding software is used to treat the positions of the arc lines as guide stars. The guiding software sends any required adjustments to mechanical piezo-electric actuators which move the mirror sending light to the camera removing any drift in the position of the arc lines. The current configuration using an sCMOS detector provides a precision of 3.5 milli-pixels equivalent to 4 m s−1 in a standard laboratory environment.
Probing the Properties of Gaia-CRF2 Quasars at the Faintest Magnitudes
Authors: Liao Shilong , Qi Zhaoxiang , Cao Zihuang , Tang Zhenghong
Published: January 2021

Gaia data release 2 (DR2) provides the best non-rotating optical frame aligned with the radio frame (ICRF) thanks to the inclusion of about half-million quasars in the five-parameter astrometric solution. We cross-match with Gaia DR2 the quasars from Large Quasar Astrometric Catalogue, Sloan Digital Sky Survey and LAMOST, obtaining 208,743 new sources (denominated as KQCG), and most of them are fainter than G = 19. Given their crucial diagnostic role for characterizing the properties of the celestial reference frame, we aim to probe more accurately the properties of the reference frame at the faintest magnitudes. Combining them with the quasars already identified in DR2, we estimate the moving mean of parallaxes and proper motions. The features of the proper motion are analyzed by means of vectorial spherical harmonics; the scalar field of parallaxes is expanded into spherical harmonics to investigate their spatial correlation, which reveals an angular scale of systematics of ≈18° with a rms amplitude of 13 μas. The global moving mean of the parallaxes and proper motions are calculated. The amplitude of proper motion bias can be up to ∼10 μas yr−1 in some sky regions for both components, and these biases seem to be related to the patterns of the scanning law. The reference frame exhibits a (−6, −5, −5) ± 1 μas yr−1 spin in the northern hemisphere and a spin of (0, +1, +3) ± 1 μas yr−1 in the southern one, which may be caused by the star contamination. The quadrupolar anisotropy of the proper motion filed is analyzed, where a significant quadrupolar signal (the largest component’s amplitude is up to −15 μas yr−1) is found.
Thermodynamics of warped anti-de Sitter black holes under scattering of scalar field *
Authors: Gwak Bogeun
Published: January 2021

We investigate the thermodynamics and stability of the horizons in warped anti-de Sitter black holes of the new massive gravity under the scattering of a massive scalar field. Under scattering, conserved quantities can be transferred from the scalar field to the black hole, thereby changing the state of the black hole. We determine that the changes in the black hole are well coincident with the laws of thermodynamics. In particular, the Hawking temperature of the black hole cannot be zero in the process as per the third law of thermodynamics. Furthermore, the black hole cannot be overspun beyond the extremal condition under the scattering of any mode of the scalar field.
Refining the cold atom pressure standard
Authors: Shen Pinrui , Madison Kirk W , Booth James L
Published: January 2021

In our previous work (Shen et al 2020 Metrologia
57 025015; Booth et al 2019 New J. Phys.
21 102001), we have reported the first primary quantum pressure standard based on the loss rate of cold rubidium atoms from a magnetic trap. We have shown that this standard is self-calibrating. That is, the single parameter required to quantify the pressure or particle flux impinging on the sensor atoms,

σ

t
o
t

v

, can be determined experimentally. In this paper, we refine our procedure to extract the trap loss rate coefficient by expressing the measured trap loss rate of the rubidium atoms as a convolution of the universal loss rate expression from Shen et al (2020 Metrologia
57 025015) and Booth et al (2019 New J. Phys.
21 102001) with the energy distribution of the rubidium atoms in the trap. We report improved

σ

t
o
t

v

values for 87Rb–X (X = He, Ar, Xe, H2, N2, and CO2) collision pairs. All are systematically higher than our previously reported values, although the differences are less than 2%. The calibration factor of an ionization gauge for nitrogen obtained using the cold atom standard, i
g = 0.950 (19), agrees with the value obtained by NIST, i
g = 0.940 (26) calibrated against their orifice flow standard.
Surface blistering and deuterium retention behaviors in pure and ZrC-doped tungsten exposed to deuterium plasma
Authors: Zhang Xue-Xi , Qiao Li , Zhang Hong , Li Yu-Hong , Wang Peng , Liu Chang-Song
Published: January 2021

Surface blistering and deuterium (D) retention behaviors in pure tungsten (W) and 0.5 wt% ZrC-doped W alloy (WZC) exposed to D plasma have been investigated as a function of incident D fluence up to 2.6 × 1025 D m−2. Surface observations show that large-sized blisters (∼8–10 μm) and a few small blisters (<2 μm) are formed on the W samples. For WZC, the surface of the samples is covered by a high density of small blisters (<1 μm), and no blister larger than 2 μm is found. Cross section views show that the large-sized blisters originate from subsurface grain boundaries, and the small blisters originate from intra-granular cavities at depths much closer to the surface. The intra-granular blisters are preferentially formed on the grains with a normal direction close to [111] for both types of sample. The inter-granular blisters formed in pure W are significantly suppressed in WZC, and the fluence threshold for blister formation in WZC is lower than that in W. The D depth distributions indicate that the implanted D is mainly retained in the near-surface region of WZC and W. Besides, a higher and broader D peak is observed at a depth of between 0.1–0.25 μm in WZC, but the intensity and width of the D peak is lower and thinner in W. The desorption spectra of WZC shift to the lower temperature side as compared to W, and the total retained D amount in WZC and W is comparable in the fluence range of 2.8 × 1024–2.6 × 1025 D m−2.
Global water scarcity including surface water quality and expansions of clean water technologies
Authors: van Vliet Michelle T H , Jones Edward R , Flörke Martina , Franssen Wietse H P , Hanasaki Naota , Wada Yoshihide , Yearsley John R
Published: January 2021

Water scarcity threatens people in various regions, and has predominantly been studied from a water quantity perspective only. Here we show that global water scarcity is driven by both water quantity and water quality issues, and quantify expansions in clean water technologies (i.e. desalination and treated wastewater reuse) to ‘reduce the number of people suffering from water scarcity’ as urgently required by UN’s Sustainable Development Goal 6. Including water quality (i.e. water temperature, salinity, organic pollution and nutrients) contributes to an increase in percentage of world’s population currently suffering from severe water scarcity from an annual average of 30% (22%–35% monthly range; water quantity only) to 40% (31%–46%; both water quantity and quality). Water quality impacts are in particular high in severe water scarcity regions, such as in eastern China and India. In these regions, excessive sectoral water withdrawals do not only contribute to water scarcity from a water quantity perspective, but polluted return flows degrade water quality, exacerbating water scarcity. We show that expanding desalination (from 2.9 to 13.6 billion m3month−1) and treated wastewater uses (from 1.6 to 4.0 billion m3month−1) can strongly reduce water scarcity levels and the number of people affected, especially in Asia, although the side effects (e.g. brine, energy demand, economic costs) must be considered. The presented results have potential for follow-up integrated analyses accounting for technical and economic constraints of expanding desalination and treated wastewater reuse across the world.