bluuebunny/crossref_metadata_2025 huggingface dataset:
Infraspecific Chemical Variability and Biological Activity of Casearia sylvestris from Different Brazilian Biomes
Authors: Bueno Paula Carolina Pires , Abarca Luis Francisco Salomé , Anhesine Naira Buzzo , Giffoni Maíra Silva , Pereira Fabiola Manhas Verbi , Torres Roseli Buzaneli , de Rayran Walter RamosSousa , Ferreira Paulo Michel Pinheiro , Pessoa Claudia , Cavalheiro Alberto José
Published: December 2020

Casearia sylvestris is an outstanding representative of the Casearia genus. This representability comes from its distinctive chemical profile and pharmacological properties. This species is widespread from North to South America, occurring in all Brazilian biomes. Based on their morphology, 2 varieties are recognized: C. sylvestris var. sylvestris and C. sylvestris var. lingua. Despite the existence of data about their chemical composition, a deeper understanding of the specialized metabolism correlation and variation in respect to environmental factors and its repercussion over their biological activities was still pending. In this study, an UHPLC-DAD-based metabolomics approach was employed for the investigation of the chemical variation of 12 C. sylvestris populations sampled across 4 Brazilian biomes and ecotones. The correlation between infraspecific chemical variability and the cytotoxic and antioxidant activities was achieved by multivariate data analysis. The analyses showed that C. sylvestris var. lingua prevailed at Cerrado areas, and it was correlated with lower cytotoxic activity and high level of glycosylated flavonoids. Among them, narcissin and isorhamnetin-3-O-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranoside showed good correlation with the antioxidant activity. Conversely, C. sylvestris var. sylvestris prevailed at the Atlantic Forest areas, and it was associated with high cytotoxic activity and high content of clerodane diterpenoids. Different casearins showed good correlation (R2  = 0.3 – 0.70) with the cytotoxic activity. These findings highlighted the great complexity among different C. sylvestris populations, their chemical profile, and the related biological activities. Consequently, it can certainly influence the medicinal properties, as well as the quality and efficacy, of C. sylvestris phytomedicines.
Psychotropic Drug Use in Children with Autism Spectrum Disorder Admitted to a Training and Research Hospital Outpatient Clinic: A Retrospective Cross-Sectional Study
Authors: Uygun Sabide Duygu , Çakmak Fatma Hülya , Canlı Merve , Temeltürk Rahime Duygu , Efe Ayşegül , Gürel Yusuf , Açıkel Sadettin Burak , Çetinkaya Miray
Published: December 2020

This study aimed to examine demographic and clinical variables, psychiatric comorbidities, the prevalence of psychotropic drug use, relationships between drug use, demographic and clinical variables, and predictors of drug use in children with autism spectrum disorder (ASD) admitted to a training and research hospital outpatient clinic. Four hundred and eleven children with ASD admitted to the Department of Child and Adolescent Psychiatry, Dr. Sami Ulus Maternity and Children's Health and Diseases Training and Research Hospital, between October 1, 2019 and December 31, 2019, were retrospectively reviewed. Demographic and clinical variables, psychiatric comorbidities, and characteristics of drug use for the cases were recorded. Psychotropic drug use was found in 34.3% (n = 141) of the cases. Our results revealed male sex and psychiatric comorbidity as predictors of psychotropic drug use. Antipsychotics were the most prescribed drugs, and the most common psychiatric comorbidity was conduct disorder. Also, children with ASD who had been toilet-trained, and could express sentences but were illiterate, were using psychotropic drugs more often than others. Future multicentered, large clinic-based studies from training and research hospitals should focus on trends of treatment in psychiatric comorbidities accompanying ASD, and constitute a systematic approach for the psychopharmacological treatment of these cases.
Intrinsic nanostructures on the (001) surface of strontium titanate at low temperatures
Authors: Hamalii V. O. , Peschanskii A. V. , Popov A. I. , Krainyukova N. V.
Published: December 2020

Atomically smooth (001) surfaces of SrTiO3 cut from the high-quality single crystals at two different miscut angles 0.9 and 7.0 deg between the real flat surfaces and crystallographic planes (001) were analyzed by means of the reflection high energy electron diffraction (RHEED) method from the room down to liquid helium temperatures. The diffraction patterns typical of the RHEED geometry close to ideal for a small miscut angle and those exhibiting distinct features of the specific periodicity associated with regular steps, which form due to the larger miscut angle, are presented. The surface symmetry and energetics were shown to impose differences in lattice parameters in parallel to a surface with respect to the bulk. This effect results in weak incommensurability between lattice parameters in surface layers and the bulk values relaxed due to step edges and misfit dislocations. The special surface nanostructures formed on the etched surfaces treated in chemically active solvents are also analyzed. The intrinsic nanostructures on single crystal surfaces open new prospects for applications when the ordered and controlled nanoscale architecture is required.
Low-temperature luminescence of catangasite single crystals under excitation by vacuum ultraviolet synchrotron radiation
Authors: Kozlova Anna P. , Buzanov Oleg A. , Pankratova Viktorija , Pankratov Vladimir
Published: December 2020

The luminescent properties of Ca3TaGa3Si2O14 (CTGS, catangasite) single crystals have been studied by means of the vacuum ultraviolet excitation spectroscopy utilizing synchrotron radiation from 1.5 GeV storage ring of MAX IV synchrotron facility. Two emission bands at 320 nm (3.87 eV) and 445 nm (2.78 eV) have been detected. Examining excitation spectra in vacuum ultraviolet spectral range, the 320 nm emission band was explained as the emission band of self-trapped exciton in CTGS single crystal. Its atomic structure is discussed. It is also proposed that the 445 nm (2.78 eV) emission in the CTGS is due to the F centers, which have shown a well-resolved excitation (absorption) band at 5.1 eV (243 nm).
Ab initio calculations of structural, electronic and vibrational properties of BaTiO3 and SrTiO3 perovskite crystals with oxygen vacancies
Authors: Rusevich L. L. , Kotomin E. A. , Zvejnieks G. , Popov A. I.
Published: December 2020

The first-principles (ab initio) computations of the structural, electronic, and phonon properties have been performed for cubic and low-temperature tetragonal phases of BaTiO3 and SrTiO3 perovskite crystals, both stoichiometric and non-stoichiometric (with neutral oxygen vacancies). Calculations were performed with the CRYSTAL17 computer code within the linear combination of atomic orbitals approximation, using the B1WC advanced hybrid exchange-correlation functional of the density-functional-theory (DFT) and the periodic supercell approach. Various possible spin states of the defective systems were considered by means of unrestricted (open shell) DFT calculations. It was demonstrated that oxygen reduction leads to the appearance of new local vibrational modes associated with oxygen vacancies and new first-order peaks in the Raman spectra, which could be used for defect identification. The calculated Raman spectra for different vacancy positions and spins of the system, as well as other properties of defective crystals, are compared with the relevant experimental data.
X-ray absorption and Raman spectroscopy studies of tungstates solid solutions ZncNi1−cWO4 (c = 0.0−1.0)
Authors: Bakradze G. , Kalinko A. , Kuzmin A.
Published: December 2020

The influence of thermal disorder and static distortions on the local structure in microcrystalline solid solutions of tungstates ZncNi1−cWO4 with c = 0.0−1.0 was investigated using temperature-dependent (10–300 K) x-ray absorption spectroscopy (XAS) at the W L3-edge. In addition, the vibrational properties of the solid solutions were studied by Raman spectroscopy. Our results indicate that the formation of solid solutions is accompanied by strong structural relaxations leading to the changes in the [WO6] octahedra distortions, which, in turn, affect the vibrational properties of tungstates. In particular, the frequency and band width of the highest W—O stretching mode at about 900 cm−1 show distinct composition dependence, following the local structure modifications as revealed by XAS.
Multifunctional composite kirigami skins for aerodynamic control
Authors: Gamble Lawren , Lamoureux Aaron , Shtein Max
Published: December 2020

The development of low-altitude unmanned aerial vehicles (UAVs) has been proposed for many high-impact civilian-centered applications such as expanding telecommunication networks in remote locations, improved weather monitoring, and terrain surveying. Such missions, which can last anywhere from hours to days, rely on efficient, lightweight, and high-aspect ratio designs to minimize energy consumption. We investigate a method of aerodynamic control that also permits energy harvesting through surface texturing on aircraft wings using multifunctional kirigami composites. These kirigami skins produce 3D surface features when axially strained and have been manufactured using thin-film solar cells. Here, we show that when actuated, these 3D features increase the drag over the wings, which can be used to control yaw. Wind tunnel experiments were conducted to quantify the effects of kirigami actuation on aerodynamic lift, drag, and yaw moment. These results demonstrate excellent yaw-control capabilities and delayed aerodynamic stall, indicating that the actuated kirigami features may delay flow separation. The implied multifunctionality of these kirigami skins is ideal for low-altitude UAVs, which benefit from both lightweight energy sources and actuators.
High-performance germanium quantum dot photodetectors: Response to continuous wave and pulsed excitation
Authors: Shi S. , Zaslavsky A. , Pacifici D.
Published: December 2020

Efficiency and response speed are key figures of merit for high-performance photodetectors, with high efficiency often obtained at the expense of slow photoresponse. Here, we report on germanium quantum dot photodetectors (Ge QD PDs) with a 25-nm-thick active layer that possesses both high internal quantum efficiency (IQE) and fast photoresponse, yet is still based on simple design and fabrication. We characterize these devices with continuous wave (CW) and pulsed excitation at room temperature as a function of incident power and applied bias. Under the reverse bias of –4 V, the IQE approaches ∼2000% over a broad spectral range (λ = 500–800 nm). The transient photoresponse speed to a 4.5 ns laser pulse at λ = 640 nm is under 20 ns. Furthermore, we observe an interesting phenomenon: by superimposing a weak CW HeNe laser beam (λ= 632.8 nm) on the laser pulse, we obtain an optically tunable photoresponse while retaining fast speed. This study elucidates the role of photocarrier generation, trapping, and hopping in the percolative Ge QD oxide matrix and helps explain the observed high gain and fast response speed. The demonstrated IQE and nanosecond response time render our devices suitable for low-light detection and imaging.
Characterization of eigenstates interface-modulated in GaAs (631) multi-quantum well heterostructures
Authors: Perea-Parrales F. E. , Espinosa-Vega L. I. , Mercado-Ornelas C. A. , Belio-Manzano A. , Cortes-Mestizo I. E. , Sánchez-Balderas G. , Valdez-Pérez Donato , Yee-Rendón C. M. , Méndez-García Víctor H.
Published: December 2020

By taking advantage of the GaAs (631) corrugation self-assembled on top of multi-quantum well heterostructure interfaces, the modulation of the confined state wave functions (eigenstates) has been achieved, attaining quasi-one-dimensional or fractional dimension eigenstates. Two different theoretical approaches were used to compute the energy shift of subband optical transitions as a function of the interface corrugation geometrical configuration. For large nominal quantum well widths and small corrugation amplitude, the perturbation theory was employed, while a modified Lanczos algorithm assisted us to calculate the shifts when the corrugation amplitude was comparable to the nominal quantum well width. Experimentally, the heterostructures were grown by molecular beam epitaxy on (001) and (631) oriented substrates, where the quasi-one-dimensional ordering was reached by changing the As to Ga molecular beam fluxes ratio. It was found that the corrugated interfaces (i) break the wave function's in-plane symmetry, allowing transitions that, in principle, must be forbidden and (ii) induce blue shifts or red shifts in the order of 10 meV to the energy spectrum of the quantum wires depending on the lateral and vertical periodicities, exhibiting the presence of a lateral confinement system. The main result is the effective modulation of eigenstates through the interface corrugation control. Additionally, it was found that the interface modulation effect is greater for harmonic (n > 1) heavy (and light) hole subbands than for the ground states.
Stability of spatially discordant repolarization alternans in cardiac tissue
Authors: Huang Chunli , Song Zhen , Di Zengru , Qu Zhilin
Published: December 2020

Cardiac alternans, a period-2 behavior of excitation and contraction of the heart, is a precursor of ventricular arrhythmias and sudden cardiac death. One form of alternans is repolarization or action potential duration alternans. In cardiac tissue, repolarization alternans can be spatially in-phase, called spatially concordant alternans, or spatially out-of-phase, called spatially discordant alternans (SDA). In SDA, the border between two out-of-phase regions is called a node in a one-dimensional cable or a nodal line in a two-dimensional tissue. In this study, we investigate the stability and dynamics of the nodes and nodal lines of repolarization alternans driven by voltage instabilities. We use amplitude equation and coupled map lattice models to derive theoretical results, which are compared with simulation results from the ionic model. Both conduction velocity restitution induced SDA and non-conduction velocity restitution induced SDA are investigated. We show that the stability and dynamics of the SDA nodes or nodal lines are determined by the balance of the tensions generated by conduction velocity restitution, convection due to action potential propagation, curvature of the nodal lines, and repolarization and coupling heterogeneities. Our study provides mechanistic insights into the different SDA behaviors observed in experiments.
Electric-field-induced strain of (Li,Na,K)NbO3-based multilayered piezoceramics under electromechanical loading
Authors: Nishiyama Hiroshi , Martin Alexander , Hatano Keiichi , Kishimoto Sumiaki , Sasaki Nobuhiro , Khansur Neamul H. , Webber Kyle G. , Kakimoto Ken-ichi
Published: December 2020

Lead-free (Li,Na,K)NbO3-based multilayered piezoceramics were prepared, and their large-signal piezoelectric properties, under combined electrical and mechanical loadings, were characterized from 25 °C to 100 °C. Under zero stress, the multilayer exhibited a high large-signal piezoelectric constant d33∗ (=Smax/Emax) ≈ 350 pm/V with an applied unipolar field of 6 kV/mm. The stress-dependent d33∗, with a unipolar field of 6 kV/mm, featured a pronounced sensitivity to the electric field with an evolving peak at −80 MPa, which was not observed at 100 °C. The disappearance of the evolving peak with increasing temperature suggests a strong influence of the crystallographic phase on the electromechanical properties of (Li,Na,K)NbO3-based multilayers. Further investigations of the stress–strain loop and stress–polarization change revealed that the field-dependent peak below 100 °C was due to the non-180° domain orientation induced by the combined electric field and compressive stress.
Stability analysis for cylindrical Couette flow of compressible fluids
Authors: Fronsdal Christian
Published: December 2020

A new analysis of basic Couette flow is based on an action principle for compressible fluids with a Hamiltonian as well as a kinetic potential. An effective criterion for stability recognizes the tensile strength of water. This interpretation relates the problem to capillary action and to metastable configurations (Berthelot’s negative pressure experiment of 1850). We calculate the pressure and density profiles and find that the first instability of basic Couette flow is localized near the bubble point. This theoretical prediction has been confirmed by recent experiments. The theory is the result of merging the two versions of classical hydrodynamics, as advocated by Landau for superfluid helium II. In an inspired paper, Landau, L. [“Theory of the superfluidity of helium II,” Phys. Rev. 60, 356–358 (1941)] introduced the idea of two independent flows, “phonons” and “rotons,” with strong emphasis on the idea that there is only one kind of fluid. The dynamical variables include two flows but only one density variable. In this paper, two-flow dynamics is created by merging two actions, neither by choosing between them nor by combining the two vector fields as in the Navier–Stokes equation. At rest, as contributions to the mass flow, they cancel, but a non-zero kinetic energy, kinetic potential, and non-zero angular momentum remain, and are manifest as liquid tension, as it is well known to exist through the observation of the meniscus and configurations with negative pressure. The immediate effect of merging the two versions of classical hydrodynamics in a unique theory based on an action principle is to provide a Hamiltonian and a kinetic potential for compressible fluids with rotational flow. This theory gives a very satisfactory characterization of the limit of stability of the most basic Couette flow. The inclusion of a vector field that is not a gradient has the additional effect of introducing spin, which explains a most perplexing experimental discovery: the ability of frozen helium to remember its angular momentum (spin).
On impact ionization and avalanche in gallium nitride
Authors: Ji Dong , Chowdhury Srabanti
Published: December 2020

This paper is dedicated to discussing the physics and applications of avalanche on III-Nitrides, primarily using Gallium Nitride as the example. Understanding the breakdown phenomenon in wide bandgap materials is of great interest to the device and circuit community as it directly impacts design and applications with these emerging semiconductors. In this paper, first, we go over the various approaches that have been reported on estimating the impact ionization coefficients in GaN, then discuss about the estimation of the critical electric field for punch-through and non-punch-through designs, and, finally, go over two avalanche-based devices that we have recently demonstrated.
Effect of the range of particle cohesion on the phase behavior and thermodynamic properties of fluids
Authors: Sadus Richard J.
Published: December 2020

Molecular simulations are performed for the (m + 1, m) potential to systematically investigate the effect of changing the range of particle cohesion on both vapor–liquid equilibria and thermodynamic properties of fluids. The results are reported for m = 4–11, which represent a progressive narrowing of the potential energy well. The conventional Lennard-Jones potential is used as a reference point for normal fluid behavior. Small values of m result in a broadening of the phase envelope compared with the Lennard-Jones potential, whereas a contraction is observed in other cases. The critical properties are reported, and a relationship between the critical temperature and the Boyle temperature is determined. The low values of the critical compressibility factor when m < 6 reflect the behavior observed for real fluids such as n-alkanes. The results for supercritical thermodynamic properties are much more varied. Properties such as pressure, potential energy, isochoric thermal pressure coefficient, and thermal expansion coefficient vary consistently with m, whereas other properties such as the Joule–Thomson coefficient exhibit much more nuanced behavior. Maximum and minimum values are reported for both the isochoric heat capacity and isothermal compressibility. A minimum in the speed of sound is also observed.
Flows between parallel plates: Analytical solutions of regularized 13-moment equations for inverse-power-law models
Authors: Hu Zhicheng , Yang Siyao , Cai Zhenning
Published: December 2020

We study the structure of stationary channel flows predicted by the regularized 13-moment equations. Compared with the work of Taheri et al. [“Couette and Poiseuille microflows: Analytical solutions for regularized 13-moment equations,” Phys. Fluids 21, 017102 (2009)], we focus on gases whose molecules satisfy the general inverse power law. The analytical solutions are obtained for the semi-linear equations, and the structures of Couette, Fourier, and Poiseuille flows are solved by coupling the general solutions with newly derived boundary conditions. The results show excellent agreement with the reference solution in the slip-flow regime. Our results also show that the R13 equations derived from inverse-power-law models can have better accuracy than the R13 equations of Maxwell molecules with altered viscosity.
Stability of cationic silver doped gold clusters and the subshell-closed electronic configuration of AgAu14+
Authors: Ferrari Piero , Delgado-Callico Laia , Lievens Peter , Baletto Francesca , Janssens Ewald
Published: December 2020

Silver doping is a valuable route to modulate the structural, electronic, and optical properties of gold clusters. We combine photofragmentation experiments with density functional theory calculations to investigate the relative stability of cationic Ag doped Au clusters, AgAuN−1+ (N ≤ 40). The mass spectra of the clusters after photofragmentation reveal marked drops in the intensity of AgAu8+, AgAu14+, and AgAu34+, indicating a higher relative stability of these sizes. This is confirmed by the calculated AgAuN−1+ (N ≤ 17) dissociation energies peaking for AgAu6+, AgAu8+, and AgAu14+. While the stability of AgAu6+ and AgAu8+ can be explained by the accepted electronic shell model for metal clusters, density of states analysis shows that the geometry plays an important role in the higher relative stability of AgAu14+. For this size, there is a degeneracy lifting of the 1D shell, which opens a relatively large HOMO–LUMO gap with a subshell-closed 1S21P41P21D6 electronic configuration.
Vertical Breadboard Safety, Methods, and Uses
Authors: Shirk Michael
Published: December 2020

The consideration and use of vertical breadboards to many laser users is a novel idea. This chapter provides a comprehensive discussion and explanation of the topic. Furthermore, it is written by a user and developer of systems using such breadboards. The reader of this chapter will learn the real-world pros and cons of the application of vertical breadboards.
Eye Openers on Laser Protective Eyewear
Authors: Bothner David
Published: December 2020

Every discussion of laser protective eyewear is also a discussion about lasers, and there is no understanding how laser safety works (let alone determining what eyewear is required for safe operation of a laser system) without understanding the scope of laser concepts and issues. This chapter seeks to explain laser protective eyewear, coming from an individual who specializes in the manufacturing of such eyewear.
Laser Safety for Very High Power Lasers
Authors: King Jamie J.
Published: December 2020

What we call high power lasers today was a wild dream in the 1960s. What we refer to as very high power lasers was something simply unimaginable. Operating in the tens to hundreds of kilowatts, these lasers are in a class truly by themselves. They present a hazard that is immediately dangerous to life and health and require great respect in their operations. This chapter introduces the reader to issues and challenges that should be addressed before considering the use of very high power lasers.
Effects of magnetic frequency and the coupled magnetic-mechanical loading on a ferromagnetic shape memory alloy
Authors: Wu Hong-Hui , Ke Yubin , Zhu Jiaming , Wu Zhenduo , Wang Xun-Li
Published: December 2020

In the present work, the microstructure evolution and macro-response of a ferromagnetic shape memory alloy under stimuli of magnetic fields with different frequency and coupled magnetic-mechanical loading are investigated via a real-space phase field simulation. It is found that the coercive field is reduced from 0.724 to 0.423 with the magnetic frequency f decrease from

2.5
×

10

−
5

Hz to

0.833
×

10

−
5

Hz, wherein the concomitant domain wall motion and magnetization rotation are captured as well. Moreover, simulation results demonstrate that, under the coupled magnetic-mechanical loading, the coercive field of the magnetic hysteresis loop could be reduced by applying a compressive strain perpendicular to the magnetic field direction. The domain evolution is mainly divided into three types during the coupled magnetic-mechanical loading, namely (a) domain wall motion with the magnetization rotation, (b) pure magnetization rotation, and (c) 180° domain coordinated domain switching. To better understand the domain evolution, we propose an index

S
=

m
1

avg

+

m
2

avg

, with

m
1

avg

and

m
2

avg

indicating the absolute value of the averaged magnetization component

m
1

and

m
2

over the whole studied system, to characterize the magnetization change during the microstructure evolution.
Ag-nanoparticles-loaded Ba0.85Ca0.15Ti0.9Zr0.1O3 for multicatalytic dye degradation
Authors: Sharma Moolchand , Singh Gurpreet , Vaish Rahul
Published: December 2020

Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZTO) ferroelectric ceramic loaded with Ag nanoparticles (NPs) was explored for its photo/piezocatalytic performance. The presence of Ag loading on BCZTO ceramic was confirmed using electron microscopes. X-ray photoelectron spectroscopy revealed the metallic chemical state of Ag NPs loaded on the surface of BCZTO ceramic. The absorbance spectrum of the Ag-loaded BCZTO sample showed a visible light absorption hump due to the phenomenon of surface plasmonic resonance. During the photocatalysis process, the

˜

99% of rhodamine B (RB) dye was degraded in aqueous solution using the Ag-loaded BCZTO sample, showing its promising photocatalysis activity. During the piezocatalysis process, the

˜

95% of RB dye was degraded using the Ag-loaded BCZTO sample, showing its promising piezocatalytic activity. The ·OH radical species were found responsible for the photocatalytic and piezocatalytic performance. The photo/piezocatalytic performance was found to be consistent over five cycles, indicating promising reusability of the Ag-loaded BCZTO sample.
A layered single-side readout depth of interaction time-of-flight-PET detector
Authors: Bläckberg L , Sajedi S , El Fakhri G , Sabet H
Published: December 2020

We are exploring a scintillator-based PET detector with potential of high sensitivity, depth of interaction (DOI) capability, and timing resolution, with single-side readout. Our design combines two previous concepts: (1) multiple scintillator arrays stacked with relative offset, yielding inherent DOI information, but good timing performance has not been demonstrated with conventional light sharing readout. (2) Single crystal array with one-to-one coupling to the photodetector, showing superior timing performance compared to its light sharing counterparts, but lacks DOI. The combination, where the first layer of a staggered design is coupled one-to-one to a photodetector array, may provide both DOI and timing resolution and this concept is here evaluated through light transport simulations. Results show that: (1) unpolished crystal pixels in the staggered configuration yield better performance across all metrics compared to polished pixels, regardless of readout scheme. (2) One-to-one readout of the first layer allows for accurate DOI extraction using a single threshold. The number of multi pixel photon counter (MPPC) pixels with signal amplitudes exceeding the threshold corresponds to the interaction layer. This approach was not possible with conventional light sharing readout. (3) With a threshold of 2 optical photons, the layered approach with one-to-one coupled first layer improves timing close to the MPPC compared to the conventional one-to-one coupling non-DOI detector, due to effectively reduced crystal thickness. Single detector timing resolution values of 91, 127, 151 and 164 ps were observed per layer in the 4-layer design, to be compared to 148 ps for the single array with one-to-one coupling. (4) For the layered design with light sharing readout, timing improves with increased MPPC pixel size due to higher signal per channel. In conclusion, the combination of straightforward DOI determination, good timing performance, and relatively simple design makes the proposed concept promising for DOI-Time-of-Flight PET detectors.
Improvement in sampling and modulation of multiplexing with temporal shuttering of adaptable apertures in a brain-dedicated multi-pinhole SPECT system
Authors: Zeraatkar Navid , Auer Benjamin , Kalluri Kesava S , May Micaehla , Momsen Neil C , Richards R Garrett , Furenlid Lars R , Kuo Phillip H , King Michael A
Published: December 2020

We are developing a multi-detector pinhole-based stationary brain-dedicated SPECT system: AdaptiSPECT-C. In this work, we introduced a new design prototype with multiple adaptable pinhole apertures for each detector to modulate the multiplexing by employing temporal shuttering of apertures. Temporal shuttering of apertures over the scan time provides the AdaptiSPECT-C with the capability of multiple-frame acquisition. We investigated, through analytic simulation, the impact of projection multiplexing on image quality using several digital phantoms and a customized anthropomorphic phantom emulating brain perfusion clinical distribution. The 105 pinholes in the collimator of the system were categorized into central, axial, and lateral apertures. We generated, through simulation, collimators of different multiplexing levels. Several data acquisition schemes were also created by changing the imaging time share of the acquisition frames. Sensitivity increased by 35% compared to the single-pinhole-per-detector base configuration of the AdaptiSPECT-C when using the central, axial, and lateral apertures with equal acquisition time shares within a triple-frame scheme with a high multiplexing scenario. Axial and angular sampling of the base configuration was enhanced by adding the axial and lateral apertures. We showed that the temporal shuttering of apertures can be exploited, trading the sensitivity, to modulate the multiplexing and to acquire a set of non-multiplexed non-truncated projections. Our results suggested that reconstruction benefited from utilizing both non-multiplexed projections and projections with modulated multiplexing resulting in a noticeably reduction in the multiplexing-induced image artefacts. Contrast recovery factor improved by 20% (9%) compared to the base configuration for a Defrise (hot-rod) phantom study when the central and axial (lateral) apertures with equal time shares were combined. The results revealed that, as an overall trend at each simulated multiplexing level, lowest normalized root-mean-square errors for the brain gray-matter regions were achieved with the combined usage of the central apertures and axial/lateral apertures.
Evolution of vortex matter, phase diagram, and upper critical field in the FeSe1−x
S
x
system
Authors: Vlasenko V A , Sadakov A V , Romanova T A , Yu Gavrilkin S , Dik A V , Sobolevskiy O A , Massalimov B I , Chareev D A , Vasiliev A N , Maltsev E I , Kuzmicheva T E
Published: December 2020

We present a comprehensive study of vortex matter in the FeSe1−x
S
x
system with various doping degree. The influence of sulphur substitution on peak effect occurrence is studied. Additionally, we study a possible vortex liquid–vortex glass/lattice transition and find an evidence that the vortex liquid–vortex glass phase transition in FeSe1−x
S
x
has a quasi two–dimensional nature. We investigate the upper critical field behaviour in FeSe1−x
S
x
system, and found that the upper critical field is higher than that predicted by the Werthamer–Helfand–Hohenberg (WHH) model, whereas its temperature dependence could be fitted within a two-band framework. Finally, a detailed H–T phase diagram is presented.
La1−

x
Mn1−

y
O3±

δ
buffer layers on inclined substrate deposited MgO templates for coated conductors
Authors: Troshyn Oleksiy , Hoffmann Christian , Große Veit , Hänisch Jens , Becker Lucas , Gross Rudolf
Published: December 2020

Most commercial high-temperature superconducting coated conductors based on ion beam assisted MgO deposited templates use LaMnO3 (LMO) films as the terminating buffer layer. In contrast, coated conductors based on inclined substrate deposition (ISD)-MgO technology are still produced with homoepitaxial (homoepi)-MgO as the cap layer. In this work we report on the deposition of LMO buffer layers on ISD-MgO/homoepi-MgO by electron beam physical vapor deposition. The growth parameters of textured LMO films were studied systematically and their properties were optimized regarding the critical current density (J
c) of the subsequently deposited DyBa2Cu3O7−δ
(DyBCO) superconducting films. LMO films without outgrowths at the surface were obtained at growth rates of up to 4 Å s−1. Despite the formation of non-stoichiometric LMO films containing 59% La, single-phase films were obtained at substrate temperatures below 775 °C and at oxygen partial pressures of up to 4 × 10−4 mbar due to a large homogeneity region towards La. The J
c values of DyBCO films deposited on LMO were found to be independent of the LMO thickness in a range from 50 nm to 450 nm. DyBCO films on LMO reach J
c = 0.83 MA cm−2 at 77 K in zero applied field. This value is up to 30% higher than those of DyBCO films grown directly on homoepi-MgO. The wide range of LMO growth parameters and higher J
c values of DyBCO on LMO compared to DyBCO on homoepi-MgO make this material attractive for its use in manufacturing coated conductors based on ISD-MgO technology.
Endorectal digital prostate tomosynthesis (endoDPT): a proof-of-concept study
Authors: Steiner Joseph , Matthews Kenneth , Jia Guang
Published: December 2020

In this study we present endorectal digital prostate tomosynthesis (endoDPT), a proposed method of high resolution prostate imaging using an endorectal x-ray sensor and an external x-ray source. endoDPT may be useful for visualizing the fine detail of small structures such as low dose rate brachytherapy (LDRBT) seeds that are difficult to visualize with current methods. The resolution of endoDPT was characterized through measurement of the modulation transfer function (MTF) and artifact spread function (ASF) in computational and physical phantoms. The qualitative resolution of endoDPT was assessed relative to computed tomography (CT) through imaging of LDRBT seeds implanted in ex vivo canine prostates. The x-ray sensor MTF reached 10% at 11.50 mm−1, the reconstruction algorithm MTF reached a maximum at 7.08 mm−1, and the ASF was 2.5 mm (full-width at half-maximum). Fine structures in LDRBT seeds like the 0.05 mm thick shell were visible with endoDPT but not CT. All endoDPT images exhibited an overshoot artifact. The measured MTFs were consistent with other studies using similar x-ray sensors and demonstrated improved resolution compared to digital breast tomosynthesis; this result was due to the smaller endoDPT x-ray sensor detection element size and quantitatively demonstrates the high resolution of endoDPT. The ASF demonstrated worse depth resolution compared to in-plane resolution, due to partial angular sampling; partial angular sampling also caused the observed overshoot artifact in the endoDPT images. However, endoDPT still was able to visualize fine structures such as the LDRBT seed shell to a much higher degree than CT. This high-resolution visualization may be useful for improvements in patient specific LDRBT dosimetry. Overall, these results indicate endoDPT is capable of high in-plane spatial resolution and is thus well poised for optimization and studies assessing clinical utility.
Overview of cold chain development in China and methods of studying its environmental impacts
Authors: Dong Yabin , Xu Ming , Miller Shelie A
Published: December 2020

The cold chain (refrigerated supply chain) is an important application of refrigeration technologies. The capacity of the cold chain industry is growing rapidly in emerging economies such as China, leading to significant environmental impacts, especially greenhouse gas (GHG) emissions. By conducting the literature review, this study begins with presenting a comprehensive overview of the cold chain industry in China. We observed that China has a large total cold warehouse capacity but low capacity per capita. Then, we directly link the example of the cold chain in China to the methods of evaluating the GHG emissions from the cold chain industry. It is observed that existing studies either primarily focus on the lifecycle of food with less consideration on the cold chain facilities or primarily focus on the lifetime of a certain stage of the cold chain (e.g., refrigerated transportation) with less consideration on food. Neither frameworks capture the entire cold chain system. Moreover, we argue that existing studies lack investigations of the cold chain GHG emissions on the national scale. To evaluate the overall GHG emissions, we recommended that one can use the bottom-up approach. First, use the lifecycle assessment (LCA) to estimate the single-unit level (e.g., one kg food, one particular refrigerated warehouse) cold chain emissions. Second, aggregate up to the national scale by the distribution patterns of the cold chain networks. Finally, we identify the crucial future issues regarding collecting cold chain lifecycle inventory data, investigating the cold chain network and the overall environmental impacts in China, regulation and technology needs for expanding the clean refrigeration technologies, and the implications of the cold chain development to water, land, and society.
Epigenome-wide association study (EWAS) for potential transgenerational disease epigenetic biomarkers in sperm following ancestral exposure to the pesticide methoxychlor
Authors: Nilsson Eric E , Thorson Jennifer L M , Ben Maamar Millissia , Beck Daniel , Skinner Michael K
Published: December 2020

Environmental exposures such as chemical toxicants can alter gene expression and disease susceptibility through epigenetic processes. Epigenetic changes can be passed to future generations through germ cells through epigenetic transgenerational inheritance of increased disease susceptibility. The current study used an epigenome-wide association study (EWAS) to investigate whether specific transgenerational epigenetic signatures of differential DNA methylation regions (DMRs) exist that are associated with particular disease states in the F3 generation great-grand offspring of F0 generation rats exposed during gestation to the agricultural pesticide methoxychlor. The transgenerational epigenetic profiles of sperm from F3 generation methoxychlor lineage rats that have only one disease state were compared to those that have no disease. Observations identify disease specific patterns of DMRs for these transgenerational rats that can potentially serve as epigenetic biomarkers for prostate disease, kidney disease, obesity, and the presence of multiple diseases. The chromosomal locations, genomic features, and gene associations of the DMRs are characterized. Disease specific DMR sets contained DMR-associated genes that have previously been shown to be associated with that specific disease. Future epigenetic biomarkers could potentially be developed and validated for humans as a disease susceptibility diagnostic tool to facilitate preventative medicine and management of disease.
Intra-night optical variability of γ −ray detected narrow-line Seyfert1 galaxies
Authors: Ojha Vineet , Chand Hum , Krishna Gopal
Published: December 2020

We report the first attempt to systematically characterise intra-night optical variability (INOV) of the rare and enigmatic subset of Narrow-Line Seyfert1 galaxies (NLSy1s), which is marked by detection in the γ-ray band and is therefore endowed with Doppler boosted relativistic jets, like blazars. However, the central engines in these two types of AGN are thought to operate in different regimes of accretion rate. Our INOV search in a fairly large and unbiased sample of 15 γ-ray NLSy1s was conducted in 36 monitoring sessions, each lasting ≥ 3 hrs. In our analysis, special care has been taken to address the possible effect on the differential light curves, of any variation in the seeing disc during the session, since that might lead to spurious claims of INOV from such AGN due to the possibility of a significant contribution from the host galaxy to the total optical emission. From our observations, a duty cycle (DC) of INOV detection in the γ-ray NLSy1s is estimated to be around 25% - 30%, which is comparable to that known for blazars. This estimate of DC will probably need an upward revision, once it becomes possible to correct for the dilution of the AGN’s nonthermal optical emission by the (much steadier) optical emission contributed not only by the host galaxy but also the nuclear accretion disc in these high Eddington rate accretors. Finally, we also draw attention to the possibility that sharp optical flux changes on sub-hour time scale are less rare for γ-ray NLSy1s, in comparison to blazars.
New insights into time-series analysis IV: panchromatic and flux-independent period finding methods
Authors: Ferreira Lopes C E , Cross N J G , Jablonski F
Published: December 2020

New time-series analysis tools are needed in disciplines as diverse as astronomy, economics, and meteorology. In particular, the increasing rate of data collection at multiple wavelengths requires new approaches able to handle these data. The panchromatic correlated indices $K^{(s)}_{(fi)}$ and $L^{(s)}_{(pfc)}$ are adapted to quantify the smoothness of a phased light-curve resulting in new period-finding methods applicable to single- and multiband data. Simulations and observational data are used to test our approach. The results were used to establish an analytical equation for the amplitude of the noise in the periodogram for different false alarm probability values, to determine the dependency on the signal-to-noise ratio, and to calculate the yield rate for the different methods. The proposed method has similar efficiency to that found for the string length period method. The effectiveness of the panchromatic and flux-independent period finding methods in single as well as multiple wavebands that share a fundamental frequency is also demonstrated in real and simulated data.
O vi traces photoionized streams with collisionally ionized boundaries in cosmological simulations of z ∼ 1 massive galaxies
Authors: Strawn Clayton , Roca-Fàbrega Santi , Mandelker Nir , Primack Joel , Stern Jonathan , Ceverino Daniel , Dekel Avishai , Wang Bryan , Dange Rishi
Published: December 2020

We analyse the distribution and origin of O vi in the Circumgalactic Medium (CGM) of dark-matter haloes of ∼1012 M⊙ at z ∼ 1 in the VELA cosmological zoom-in simulations. We find that the O vi in the inflowing cold streams is primarily photoionized, while in the bulk volume it is primarily collisionally ionized. The photoionized component dominates the observed column density at large impact parameters (≳0.3Rvir), while the collisionally ionized component dominates closer in. We find that most of the collisional O vi, by mass, resides in the relatively thin boundaries of the photoionized streams. Thus, we predict that a reason previous work has found the ionization mechanism of O vi so difficult to determine is because the distinction between the two methods coincides with the distinction between two significant phases of the CGM. We discuss how the results are in agreement with analytic predictions of stream and boundary properties, and their compatibility with observations. This allows us to predict the profiles of O vi and other ions in future CGM observations and provides a toy model for interpreting them.
Profiling of ribose methylations in ribosomal RNA from diffuse large B-cell lymphoma patients for evaluation of ribosomes as drug targets
Authors: Krogh Nicolai , Asmar Fazila , Côme Christophe , Munch-Petersen Helga Fibiger , Grønbæk Kirsten , Nielsen Henrik
Published: December 2020

Cancer cells are addicted to ribosome biogenesis and high levels of translation. Thus, differential inhibition of cancer cells can be achieved by targeting aspects of ribosome biogenesis or ribosome function. Using RiboMeth-seq for profiling of the ∼112 2′-O-Me sites in human ribosomal RNA, we demonstrated pronounced hypomethylation at several sites in patient-derived diffuse large B-cell lymphoma (DLBCL) cell lines with a more severe perturbation in ABC-DLBCL compared to GBC-DLBCL. We extended our analysis to tumor samples from patients and demonstrated significant changes to the ribosomal modification pattern that appeared to consist of cell growth-related as well as tumor-specific changes. Sites of hypomethylation in patient samples are discussed as potential drug targets, using as an example a site in the small subunit (SSU-C1440) located in a ribosomal substructure that can be linked to DLBCL pathogenesis.
Multiorgan Crystal Deposition of an Amphoteric Drug in Rats Due to Lysosomal Accumulation and Conversion to a Poorly Soluble Hydrochloride Salt
Authors: Lenz Barbara , Brink Andreas , Mihatsch Michael J , Altmann Bernd , Niederhauser Urs , Steinhuber Bernd , Wyttenbach Nicole , Fischer Holger
Published: December 2020

Poor solubility of drug candidates mainly affects bioavailability, but poor solubility of drugs and metabolites can also lead to precipitation within tissues, particularly when high doses are tested. RO0728617 is an amphoteric compound bearing basic and acidic moieties that has previously demonstrated good solubility at physiological pH but underwent widespread crystal deposition in multiple tissues in rat toxicity studies. The aim of our investigation was to better characterize these findings and their underlying mechanism(s), and to identify possible screening methods in the drug development process. Main microscopic features observed in rat RO0728617 toxicity studies were extensive infiltrates of crystal-containing macrophages in multiple organs. Matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry revealed that these crystals contained the orally administered parent compound, and locality was confirmed to be intracytoplasmic and partly intralysosomal by electron microscopic examination. Crystal formation was explained by lysosomal accumulation of the compound followed by precipitation of the hydrochloride salt under physiological conditions in the lysosomes, which have a lower pH and higher chloride concentration in comparison to the cytosol. This study demonstrates that risk of drug precipitation can be assessed by comparing the estimated lysosomal drug concentration at a given dose with the solubility of the compound at lysosomal conditions.