bluuebunny/crossref_metadata_2025 huggingface dataset:
Bonding in nitrile photo-dissociating ruthenium drug candidates—A local vibrational mode study
Authors: McCutcheon Margaret , Freindorf Marek , Kraka Elfi
Published: June 2022

In this work, we investigated bonding features of 15 ruthenium(II) nitrile complexes of the type [Ru(tpy)(L)-(CH3CN)]n+, containing the tridentate tpy ligand (tpy = 2,2′:6′,2″-terpyridine) and various bidentate ancillary ligands L; 12 compounds originally synthesized by Loftus et al. [J. Phys. Chem. C 123, 10291–10299 (2019)] and three new complexes. We utilized local vibrational force constants derived from the local mode theory as a quantitative measure of bond strength complemented with the topological analysis of the electron density and the natural bond orbital analysis. Loftus et al. suggested that nitrile dissociation occurs after light induced singlet–triplet transition of the original complexes and they used as a measure of nitrile release efficiency quantum yields for ligand exchange in water. They observed larger quantum yields for complexes with smaller singlet–triplet energy gaps. The major goal of this work was to assess how the Ru–NC and Ru–L bond strengths in these 15 compounds relate to and explain the experimental data of Loftus et al., particularly focusing on the question whether there is a direct correlation between Ru–NC bond strength and measured quantum yield. Our study provides the interesting result that the compounds with the highest quantum yields also have the strongest Ru–NC bonds suggesting that breaking the Ru–NC bond is not the driving force for the delivery process rather than the change of the metal framework as revealed by first results of a unified reaction valley approach investigation of the mechanism. Compounds with the highest quantum yield show larger electronic structure changes upon singlet–triplet excitation, i.e., larger changes in bond strength, covalency, and difference between the singlet and triplet HOMOs, with exception of the compound 12. In summary, this work provides new insights into the interplay of local properties and experimental quantum yields forming in synergy a useful tool for fine tuning of existing and future design of new nitrile releasing ruthenium compounds. We hope that this work will bring theoretical and experimental studies closer together and serves as an incubator for future collaboration between computational chemists and their experimental colleagues.
Experimental and computational studies of the kinetics of the reaction of hydrogen peroxide with the amidogen radical
Authors: Alecu I. M. , Gao Yide , Marshall Paul
Published: June 2022

The pulsed-laser photolysis/laser-induced fluorescence method is used to study the kinetics of the reaction of NH2 with H2O2 to yield a second-order rate constant of (2.42 ± 0.55) × 10−14 cm3 molecule−1 s−1 at 412 K in 10–22 mbar of Ar bath gas. There are no prior measurements for comparison. To check this value and enable reliable extrapolation to other temperatures, we also compute thermal rate constants for this process over the temperature range 298–3000 K via multi-structural canonical variational transition-state theory with small-curvature multidimensional tunneling (MS-CVT/SCT). The CVT/SCT rate constants are derived using a dual-level direct dynamics approach utilizing single-point CCSD(T)-F12b/cc-pVQZ-F12 energies—corrected for core-valence and scalar relativistic effects—and M06-2X/MG3S geometries, gradients, and Hessians—for all stationary and non-stationary points along the reaction path. The multistructural method with torsional anharmonicity, based on a coupled torsional potential, is then employed to calculate correction factors for the rate constants, accounting for the comprehensive effects of torsional anharmonicity on the kinetics of this reaction system. The final MS-CVT/SCT rate constants are found to be in good agreement with our measurements and can be expressed in modified Arrhenius form as 2.13 × 10−15 (T/298 K)4.02 exp(−513 K/T) cm3 molecule−1 s−1 over the temperature range of 298–3000 K.
New pecS-n (n = 1, 2) basis sets for quantum chemical calculations of the NMR chemical shifts of H, C, N, and O nuclei
Authors: Rusakov Yuriy Yu. , Rusakova Irina L.
Published: June 2022

This paper demonstrates the performance of our previously suggested property-energy consistent method on the example of the generation of effective basis sets, pecS-1 and pecS-2, suited for the calculation of hydrogen, carbon, nitrogen, and oxygen chemical shifts. The new basis sets were successfully approbated in the GIAO-DFT calculations of the chemical shifts of 35 molecules using six different functionals. The pecS-1 basis set demonstrated very good accuracy, which makes this small basis set an effective means for the large-scale computations. At the same time, the pecS-2 basis set also gave very accurate results, thus putting it on a par with the other commensurate basis sets suited for the chemical shifts calculations.
Data processing of Langmuir probe I
–
V traces to obtain accurate electron temperature and density in Maxwellian plasmas
Authors: Li Jian-Quan , Xie Xin-Yao , Zhang Qing-He , Li Shu-Han , Lu Wen-Qi
Published: June 2022

The standard procedure for obtaining accurate electron temperature (Te) from Langmuir probe I–V characteristics measured in Maxwellian plasmas is studied by comparing the results of Te determined via different data-processing methods. The comparison results show that the width and position of the fitting interval in the transition region of the I–V curve as well as whether the ion collection current deducted from the I–V curve can significantly influence the calculation of Te and afford uncertainties in the calculation of electron density. The reasonable width of the linear fitting interval should be 30%–50% of the transition region width, and the results of Te are the most reliable, which are determined by the linear fitting intervals optimally selected from the electron part of I–V curves. Based on the results, a rigorous data-processing method is proposed to provide a standard procedure for obtaining reliable plasma parameters, especially accurate Te from Maxwellian plasmas using a Langmuir probe.
Chiral selecting crystallization of helical polymers: A molecular dynamics simulation for the POM-like bare helix
Authors: Yamamoto Takashi
Published: June 2022

Polymer crystallization has long been a fascinating problem and is still attracting many researchers. Most of the previous simulations are concentrated on clarifying the universal aspects of polymer crystallization using model linear polymers such as polyethylene. We are recently focusing on a nearly untouched but very interesting problem of chiral selecting crystallization in helical polymers. We previously proposed a stepwise approach using two kinds of helical polymers, simple “bare” helical polymers made of backbone atoms only such as polyoxymethylene (POM) and “general” helical polymers containing complicated side groups such as isotactic polypropylene. We have already reported on the crystallization in oligomeric POM-like helix but have observed only weak chiral selectivity during crystallization. In the present paper, we investigate the crystallization of sufficiently long POM-like polymer both from the isotropic melt and from the highly stretched melt. We find in both cases that the polymer shows a clear chiral selecting crystallization. Specifically, the observation of a single crystal growing from the isotropic melt is very illuminating. It shows that the crystal thickness and the crystal chirality are closely correlated; thicker crystals show definite chirality while thinner ones are mostly mixtures of the R- and the L-handed stems. The single crystal is found to have a marked lenticular shape, where the thinner growth front, since being made of the mixture, shows no chiral selectivity. The final chiral crystal is found to be completed through helix reversal processes within thicker regions.
Non-Hermitian planar elastic metasurface for unidirectional focusing of flexural waves
Authors: Stojanoska Katerina , Shen Chen
Published: June 2022

Metasurfaces exhibiting spatially asymmetric inner structures have been shown to host unidirectional scattering effects, benefiting areas where directional control of waves is desired. In this work, we propose a non-Hermitian planar elastic metasurface to achieve unidirectional focusing of flexural waves. The unit cells are constructed by piezoelectric disks and metallic blocks that are asymmetrically loaded. A tunable material loss is then introduced by negative capacitance shunting. By suitably engineering the induced loss profile, a series of unit cells are designed, which can individually access the exceptional points manifested by unidirectional zero reflection. We then construct a planar metasurface by tuning the reflected phase to ensure constructive interference at one side of the metasurface. Unidirectional focusing of the incident waves is demonstrated, where the reflected wave energy is focused from one direction, and zero reflection is observed in the other direction. The proposed metasurface enriches the flexibility in asymmetric elastic wave manipulation as the loss and the reflected phase can be tailored independently in each unit cell.
Influence of oxygen plasma treatment on structural and spectral changes in gold nanorods immobilized on indium tin oxide surfaces
Authors: Ramasamy Mukunthan , Ha Ji Won
Published: June 2022

Oxygen plasma treatment is commonly used to sterilize gold nanoparticles by removing chemical contaminants from their surface while simultaneously inducing surface activation and functionalization of nanoparticles for biological, electrocatalytic, or electrochemical studies. In this study, we investigate the influence of oxygen plasma treatment on structural and localized surface plasmon resonance (LSPR) spectral changes of anisotropic gold nanorods (AuNRs) immobilized on an indium tin oxide (ITO) glass substrate. Unlike AuNRs deposited on a glass slide, no noticeable structural change or deformation of AuNRs on ITO was observed while increasing the oxygen plasma treatment time. This result indicates that ITO provides structural stability to AuNRs immobilized on its surface. Additionally, single-particle scattering spectra of AuNRs showed the broadening of LSPR linewidth within 60 s of oxygen plasma treatment as a result of the plasmon energy loss contributed from plasmon damping to ITO due to the removal of capping material from the AuNR surface. Nevertheless, an increase in the surface charge on the AuNR surface was observed by narrowing the LSPR linewidth after 180 s of plasma treatment. The electrochemical study of AuNRs immobilized on ITO electrodes revealed the surface activation and functionalization of AuNRs by increasing plasma treatment. Hence, in this study, a significant understanding of oxygen plasma treatment on AuNRs immobilized on ITO surfaces is provided.
Effect of surface roughness on partition of ionic liquids in nanopores by a perturbed-chain SAFT density functional theory
Authors: Shen Gulou , Zhang Di , Hu Yongke , Zhang Xiaojie , Zhou Feng , Qian Yunhua , Lu Xiaohua , Ji Xiaoyan
Published: June 2022

In this work, the distribution and partition behavior of ionic liquids (ILs) in nanopores with rough surfaces are investigated by a two-dimensional (2D) classical density functional theory model. The model is consistent with the equation of state that combines the perturbed-chain statistical associating fluid theory and the mean spherical approximation theory for bulk fluids. Its performance is verified by comparing the theoretical predictions with the results from molecular simulations. The fast Fourier transform and a hybrid iteration method of Picard iteration and Anderson mixing are used to efficiently obtain the solution of density profile for the sizable 2D system. The molecular parameters for IL-ions are obtained by fitting model predictions to experimental densities of bulk ILs. The model is applied to study the structure and partition of the ILs in nanopores. The results show that the peak of the density profile of counterions near a rough surface is much higher than that near a smooth surface. The adsorption of counterions and removal of co-ions are enhanced by surface roughness. Thus, the nanopore with a rough surface can store more charge. At low absolute surface potential, the partition coefficient for ions on rough surfaces is lower than that on smooth surfaces. At high absolute surface potential, increasing surface roughness leads to an increase in the partition coefficient for counterions and a decrease in the partition coefficient for co-ions.
Decoupled atomic contribution boosted high thermoelectric performance in mixed cation spinel oxides ACo2O4
Authors: Srivastava Ashutosh , Mukherjee Madhubanti , Singh Abhishek Kumar
Published: June 2022

Decoupling the interdependence of various transport parameters in materials has been an intractable challenge in designing efficient thermoelectric materials. Using the first-principles density functional theory and the semi-classical Boltzmann transport theory, we demonstrate that the crucial criteria of obtaining suitable electronic and thermal transport have been achieved by utilizing the presence of mixed cations in spinel oxides. Differently coordinated cations present in spinel oxides lead to decoupled cationic contribution to the electronic and thermal transport properties. While electronic transport properties are controlled by tetrahedrally coordinated cation B (Co), the octahedrally coordinated cations A (Zn/Cd) only contribute to the thermal transport of the system. The combination of heavy bands in the electronic dispersions and tetrahedrally coordinated environment of Co results into an enhanced power factor. Additionally, the substitution of Cd leads to one order of magnitude reduction in the lattice thermal conductivity (κl) without affecting the electronic transport properties. The significant reduction in κl has been attributed to the large mass difference, and remarkably strong anharmonic phonon scattering introduced by Cd. Simultaneously achieved high power factor and low lattice thermal conductivity result in a maximum figure of merit of 1.68 in CdCo2O4 spinel oxide. The approach of decoupling atomic contributions utilizing various cationic sites demonstrates a potential route to enhance thermoelectric performance.
Quantifying the importance and location of SARS-CoV-2 transmission events in large metropolitan areas
Authors: Aleta Alberto , Martín-Corral David , Bakker Michiel A. , Pastore y Piontti Ana , Ajelli Marco , Litvinova Maria , Chinazzi Matteo , Dean Natalie E. , Halloran M. Elizabeth , Longini Ira M. , Pentland Alex , Vespignani Alessandro , Moreno Yamir , Moro Esteban
Published: June 2022

Detailed characterization of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission across different settings can help design less disruptive interventions. We used real-time, privacy-enhanced mobility data in the New York City, NY and Seattle, WA metropolitan areas to build a detailed agent-based model of SARS-CoV-2 infection to estimate the where, when, and magnitude of transmission events during the pandemic’s first wave. We estimate that only 18% of individuals produce most infections (80%), with about 10% of events that can be considered superspreading events (SSEs). Although mass gatherings present an important risk for SSEs, we estimate that the bulk of transmission occurred in smaller events in settings like workplaces, grocery stores, or food venues. The places most important for transmission change during the pandemic and are different across cities, signaling the large underlying behavioral component underneath them. Our modeling complements case studies and epidemiological data and indicates that real-time tracking of transmission events could help evaluate and define targeted mitigation policies.
Revealing the recent demographic history of Europe via haplotype sharing in the UK Biobank
Authors: Gilbert Edmund , Shanmugam Ashwini , Cavalleri Gianpiero L.
Published: June 2022

Haplotype-based analyses have recently been leveraged to interrogate the fine-scale structure in specific geographic regions, notably in Europe, although an equivalent haplotype-based understanding across the whole of Europe with these tools is lacking. Furthermore, study of identity-by-descent (IBD) sharing in a large sample of haplotypes across Europe would allow a direct comparison between different demographic histories of different regions. The UK Biobank (UKBB) is a population-scale dataset of genotype and phenotype data collected from the United Kingdom, with established sampling of worldwide ancestries. The exact content of these non-UK ancestries is largely uncharacterized, where study could highlight valuable intracontinental ancestry references with deep phenotyping within the UKBB. In this context, we sought to investigate the sample of European ancestry captured in the UKBB. We studied the haplotypes of 5,500 UKBB individuals with a European birthplace; investigated the population structure and demographic history in Europe, showing in parallel the variety of footprints of demographic history in different genetic regions around Europe; and expand knowledge of the genetic landscape of the east and southeast of Europe. Providing an updated map of European genetics, we leverage IBD-segment sharing to explore the extent of population isolation and size across the continent. In addition to building and expanding upon previous knowledge in Europe, our results show the UKBB as a source of diverse ancestries beyond Britain. These worldwide ancestries sampled in the UKBB may complement and inform researchers interested in specific communities or regions not limited to Britain.
Raf Kinase Inhibitory Protein regulates the cAMP-dependent protein kinase signaling pathway through a positive feedback loop
Authors: Lee Jiyoung , Olivieri Cristina , Ong Colin , Masterson Larry R. , Gomes Suzana , Lee Bok-Soon , Schaefer Florian , Lorenz Kristina , Veglia Gianluigi , Rosner Marsha Rich
Published: June 2022

Raf Kinase Inhibitory Protein (RKIP) maintains cellular robustness and prevents the progression of diseases such as cancer and heart disease by regulating key kinase cascades including MAP kinase and protein kinase A (PKA). Phosphorylation of RKIP at S153 by Protein Kinase C (PKC) triggers a switch from inhibition of Raf to inhibition of the G protein coupled receptor kinase 2 (GRK2), enhancing signaling by the β-adrenergic receptor (β-AR) that activates PKA. Here we report that PKA-phosphorylated RKIP promotes β-AR–activated PKA signaling. Using biochemical, genetic, and biophysical approaches, we show that PKA phosphorylates RKIP at S51, increasing S153 phosphorylation by PKC and thereby triggering feedback activation of PKA. The S51V mutation blocks the ability of RKIP to activate PKA in prostate cancer cells and to induce contraction in primary cardiac myocytes in response to the β-AR activator isoproterenol, illustrating the functional importance of this positive feedback circuit. As previously shown for other kinases, phosphorylation of RKIP at S51 by PKA is enhanced upon RKIP destabilization by the P74L mutation. These results suggest that PKA phosphorylation at S51 may lead to allosteric changes associated with a higher-energy RKIP state that potentiates phosphorylation of RKIP at other key sites. This allosteric regulatory mechanism may have therapeutic potential for regulating PKA signaling in disease states.
Lung surfactant negatively affects the photodynamic inactivation of bacteria—in vitro and molecular dynamic simulation analyses
Authors: Kassab Giulia , Diaz Tovar Johan Sebastian , Souza Lucas Miguel Pereira , Costa Rayla Kelly Magalhães , Silva Rudielson Santos , Pimentel André Silva , Kurachi Cristina , Bagnato Vanderlei Salvador
Published: June 2022

In the context of the rapid increase of antibiotic-resistant infections, in particular of pneumonia, antimicrobial photodynamic therapy (aPDT), the microbiological application of photodynamic therapy (PDT), comes in as a promising treatment alternative since the induced damage and resultant death are not dependent on a specific biomolecule or cellular pathway. The applicability of aPDT using the photosensitizer indocyanine green with infrared light has been successfully demonstrated for different bacterial agents in vitro, and the combination of pulmonary delivery using nebulization and external light activation has been shown to be feasible. However, there has been little progress in obtaining sufficient in vivo efficacy results. This study reports the lung surfactant as a significant suppressor of aPDT in the lungs. In vitro, the clinical surfactant Survanta® reduced the aPDT effect of indocyanine green, Photodithazine®, bacteriochlorin-trizma, and protoporphyrin IX againstStreptococcus pneumoniae. The absorbance and fluorescence spectra, as well as the photobleaching profile, suggested that the decrease in efficacy is not a result of singlet oxygen quenching, while a molecular dynamics simulation showed an affinity for the polar head groups of the surfactant phospholipids that likely impacts uptake of the photosensitizers by the bacteria. Methylene blue is the exception, likely because its high water solubility confers a higher mobility when interacting with the surfactant layer. We propose that the interaction between lung surfactant and photosensitizer must be taken into account when developing pulmonary aPDT protocols.
Radioresistant cells initiate lymphocyte-dependent lung inflammation and IFNγ-dependent mortality in STING gain-of-function mice
Authors: Gao Kevin MingJie , Motwani Mona , Tedder Thomas , Marshak-Rothstein Ann , Fitzgerald Katherine A.
Published: June 2022

Pediatric patients with constitutively active mutations in the cytosolic double-stranded-DNA-sensing adaptor STING develop an autoinflammatory syndrome known as STING-associated vasculopathy with onset in infancy (SAVI). SAVI patients have elevated interferon-stimulated gene expression and suffer from interstitial lung disease (ILD) with lymphocyte predominate bronchus-associated lymphoid tissue (BALT). Mice harboring SAVI mutations (STING V154M [VM]) that recapitulate human disease also develop lymphocyte-rich BALT. Ablation of either T or B lymphocytes prolongs the survival of SAVI mice, but lung immune aggregates persist, indicating that T cells and B cells can independently be recruited as BALT. VM T cells produced IFNγ, and IFNγR deficiency prolonged the survival of SAVI mice; however, T-cell-dependent recruitment of infiltrating myeloid cells to the lung was IFNγ independent. Lethally irradiated VM recipients fully reconstituted with wild type bone-marrow-derived cells still developed ILD, pointing to a critical role for VM-expressing radioresistant parenchymal and/or stromal cells in the recruitment and activation of pathogenic lymphocytes. We identified lung endothelial cells as radioresistant cells that express STING. Transcriptional analysis of VM endothelial cells revealed up-regulation of chemokines, proinflammatory cytokines, and genes associated with antigen presentation. Together, our data show that VM-expressing radioresistant cells play a key role in the initiation of lung disease in VM mice and provide insights for the treatment of SAVI patients, with implications for ILD associated with other connective tissue disorders.
The optimal docking strength for reversibly tethered kinases
Authors: Dyla Mateusz , González Foutel Nicolás S. , Otzen Daniel E. , Kjaergaard Magnus
Published: June 2022

Many kinases use reversible docking interactions to augment the specificity of their catalytic domains. Such docking interactions are often structurally independent of the catalytic domain, which allow for a flexible combination of modules in evolution and in bioengineering. The affinity of docking interactions spans several orders of magnitude. This led us to ask how the affinity of the docking interaction affects enzymatic activity and how to pick the optimal interaction module to complement a given substrate. Here, we develop equations that predict the optimal binding strength of a kinase docking interaction and validate it using numerical simulations and steady-state phosphorylation kinetics for tethered protein kinase A. We show that a kinase–substrate pair has an optimum docking strength that depends on their enzymatic constants, the tether architecture, the substrate concentration, and the kinetics of the docking interactions. We show that a reversible tether enhances phosphorylation rates most when 1) the docking strength is intermediate, 2) the substrate is nonoptimal, 3) the substrate concentration is low, 4) the docking interaction has rapid exchange kinetics, and 5) the tether optimizes the effective concentration of the intramolecular reaction. This work serves as a framework for interpreting mutations in kinase docking interactions and as a design guide for engineering enzyme scaffolds.
Warum Deutsch lernen?
Authors: Stamou Anastasia G. , Sidiropoulou Evmorfia
Published: June 2022

In the present study, we explore the discursive construction of German language learning identities on the Goethe Institute website. With this aim, we depart from critical sociolinguistic approaches to multilingualism and draw on an analytical framework which views discourse as a lens through which one can examine the ways identities are actively accomplished in particular contexts. From the analysis, it appears that on the central body of the Institute website, the German language learners are constructed as elite, global and mobile multilinguals. In contrast, the recipients of the Institute portal “Mein Weg nach Deutchland” are attached to the local and non-elite multilingual identities of immigrants / refugees. Thus, the Goethe Institute website is a socially constructed space invested with hierarchical meanings about “where” German language is an elite multilingual skill and “where” it is not.
A mitochondrial contribution to anti-inflammatory shear stress signaling in vascular endothelial cells
Authors: Coon Brian G. , Timalsina Sushma , Astone Matteo , Zhuang Zhen W. , Fang Jennifer , Han Jinah , Themen Jurgen , Chung Minhwan , Yang-Klingler Young Joo , Jain Mukesh , Hirschi Karen K. , Yamamato Ai , Trudeau Louis-Eric , Santoro Massimo , Schwartz Martin A.
Published: June 2022

Atherosclerosis, the major cause of myocardial infarction and stroke, results from converging inflammatory, metabolic, and biomechanical factors. Arterial lesions form at sites of low and disturbed blood flow but are suppressed by high laminar shear stress (LSS) mainly via transcriptional induction of the anti-inflammatory transcription factor, Kruppel-like factor 2 (Klf2). We therefore performed a whole genome CRISPR-Cas9 screen to identify genes required for LSS induction of Klf2. Subsequent mechanistic investigation revealed that LSS induces Klf2 via activation of both a MEKK2/3–MEK5–ERK5 kinase module and mitochondrial metabolism. Mitochondrial calcium and ROS signaling regulate assembly of a mitophagy- and p62-dependent scaffolding complex that amplifies MEKK–MEK5–ERK5 signaling. Blocking the mitochondrial pathway in vivo reduces expression of KLF2-dependent genes such as eNOS and inhibits vascular remodeling. Failure to activate the mitochondrial pathway limits Klf2 expression in regions of disturbed flow. This work thus defines a connection between metabolism and vascular inflammation that provides a new framework for understanding and developing treatments for vascular disease.
Collaborative smartphone experiments for large audiences with phyphox
Authors: Staacks S , Dorsel D , Hütz S , Stallmach F , Splith T , Heinke H , Stampfer C
Published: June 2022

We present methods to implement collaborative experimentation with smartphone sensors for larger audiences ranging from typical university undergraduate courses of hundreds of students in a lecture hall to world-wide outreaches on the Internet. These methods are based on the app ‘phyphox’, which is being developed by the authors, and encompass simple data collection via web forms as well as a new network interface for ‘phyphox’, allowing to collect real-time experiment data from an audience on-site or easy data submission for remote participants. Examples are given with practical considerations derived from first implementations of this method in a lecture hall with 350 undergraduate students as well as a global experiment to determine the Earth’s axial tilt with smartphones.
Nonlinear mechanisms in Al and Ti superconducting travelling-wave parametric amplifiers
Authors: Zhao Songyuan , Withington S , Thomas C N
Published: June 2022

The underlying nonlinear mechanisms behind the operation of travelling-wave parametric amplifiers (TWPAs) are important in determining their performance in terms of added noise, maximum gain, and bandwidth. We describe a method of characterising the underlying nonlinearity of a superconducting material in terms of its dissipative-reactive ratio and the response time of the underlying microscopic processes. We describe and calculate the different behaviour arising from the equilibrium supercurrent nonlinearity, which has low dissipation and fast response time, and the non-equilibrium heating nonlinearity, which has high dissipation and slow response time. We have fabricated TWPAs based on Al and Ti, and characterised their nonlinearities using our analysis. For both Al and Ti, the measured dissipative-reactive ratios and response times are quantitatively similar to predictions for the non-equilibrium heating nonlinearity. We were able to obtain more than

20

d
B

of peak power gain, although only over a narrow bandwidth of a few kilohertz. Our method of characterising the underlying nonlinearities could also be useful in the understanding and design of other superconducting nonlinear devices such as parametric up-converters, kinetic inductance Fourier transform spectrometers, and resonator parametric amplifiers.
A thermophone-based bridge circuit for the measurement of electrical and thermal properties of thin films
Authors: Tatnell D M , Heath M S , Hibbins A P , Horsell D W
Published: June 2022

Sound can be generated via modulated Joule heating of thin conductive films. Its amplitude and phase are sensitive to the electrical and thermal properties of the film. Here we show how such sound can be used to measure and quantify these properties. In particular, we experimentally determine the relative conductances of electrical paths in a multi-branched thin film, which can then be used to find the temperature dependence of the film conductance. This is achieved by nullifying the sound at a given point in the sound field using simple voltage control. This method, essentially an acoustic analogue of an electrical bridge circuit, is advantageous since it allows for electrical and thermal properties to be measured simultaneously. These attributes benefit the characterisation of complex circuit architectures, as well as thermal sensing.
A point-line-plane primitives fused localization and object-oriented semantic mapping in structural indoor scenes
Authors: Xia Linlin , Cui Jiashuo , Li Xinying , Zhang Daochang , Zhang Jingjing , Yi Linna
Published: June 2022

Visual SLAM (abbreviates ‘simultaneous localization and mapping’) is a promising solution for environment mapping. This study is devoted to a description of a semantically ensembled SLAM framework. For structural indoor scenes, the structured lines and planes can serve as the newly added constraints to improve the positioning accuracy. In this paper, we propose to comprehensively incorporate point-line-plane primitives and construct a tightly coupled camera pose estimator without any environment assumptions. In particular, the maximum number of extracted lines features is numerically determined. We further integrate a lightweight object mapping pipeline with the designed pose estimator. In this pipeline, the leveraging of fitted plane and cuboid landmarks enables an online, CPU-based dense mapping. The tests on ICL-NUIM and TUM benchmark datasets illustrate that, in comparison to ORB-SLAM2, PL-SLAM (Point and Line based SLAM), SP-SLAM (Supposed Plane SLAM) and PLP-SLAM (Point, Line and Plane fused SLAM), our design leads to superior performances in global consistency and system drift elimination. The feature detection and multi-level map reconstruction results are simultaneously provided.
Magnetoresistance of Ni/WSe2/Ni junctions: robustness against the thickness of WSe2
Authors: Yan Kun , Hu Yizhi , Suo Yan , Qin Yuxia , Chen Xiaobin
Published: June 2022

Magnetoresistive materials are vital for the development of storage devices. Using the first-principles transport simulations with nonequilibrium Green’s function calculation, we investigate the magnetoresistive properties of Ni/WSe2/Ni junctions with m-layers of WSe2 (m = 1, 2, ⋯ ,6). For m ≤ 2, the junctions are metallic inspite of the semiconducting nature of few-layer WSe2. However, the junctions exhibit transport gaps for m > 2. Interestingly, magnetoresistance of the junctions stays around 6% when there are more than one layer of WSe2 in the center, which is closely related to the robust spacial variation of interfacial properties and can be attributed to no spin flipping in tunneling regions. Our results suggest that Ni/WSe2/Ni junctions have a robust magnetoresistance which is insensitive to the thickness of WSe2.
On the effect of dose delivery temporal domain on the biological effectiveness of central nervous system CyberKnife radiosurgery applications: theoretical assessment using the concept of biologically effective dose
Authors: Moutsatsos A , Kouris P , Zoros M , Athanasiou O , Koutsarnakis C , Pantelakos P , Pantelis E
Published: June 2022

Objective: The diversity in technical configuration between clinically available radiosurgery systems, results in accordingly diverse treatment times for the same physical dose prescription, spanning from several min to more than 1 h. This, combined with evidence supporting the impact of dose delivery temporal pattern on the bio-effectiveness of low-LET radiation treatments, challenges the ‘acute exposure’ assumption adopted clinically to estimate the biological outcome of a given treatment scheme under the concept of biologically effective dose (BED). Approach: In this work, the treatment plans of 30 patients underwent CyberKnife radiosurgery for vestibular schwannoma (VS), prescribing a marginal dose of 13 Gy to the tumor, were retrospectively reviewed and the corresponding dose distributions were resolved in the temporal domain. For this purpose, the dose delivery timeline for each treatment was calculated based on relevant treatment plan data and technical specifications of the CyberKnife system, while dosimetry data were independently acquired on a CT-based digital model of each patient using an in-house developed dose calculation algorithm. Main results: Results showed that CyberKnife delivers highly inhomogeneous dose rate distributions in the temporo-spatial domain. This influences the delivered BED levels due to alterations in the sublethal damage repair (SLR) occurring within the treatment session. Using a BED framework involving SLR effects, it was shown that each physical dose iso-surface is associated with a BEDslr range. For the patient cohort studied, a typical range of 2%, with respect to the mean BEDslr value was found at 1σ. Significance: The marginal BEDslr delivered to the tumor by the prescription dose iso-surface deteriorates with treatment time, involving both beam-on time and beam-off gaps. For treatment time, T, between 21 and 50 min, this can be expressed by

BED
slr

(

Gy
2.47

)
=

−
0.35
±
2.8
%

∙
T

min

+
(
76.74
±
0.4
%
)
.

Compared to the acute exposure approach, a BED ‘loss’ of 21% is associated with the delivery of 13 Gy to the VS-tumor in 35 min.
Investigating the lateral dose response functions of point detectors in proton beams
Authors: Kretschmer Jana , Brodbek Leonie , Looe Hui Khee , van der Graaf Emiel , Jan van Goethem Marc , Kiewiet Harry , Olivari Francesco , Meyer Christoph , Poppe Björn , Brandenburg Sytze
Published: June 2022

Objective. Point detector measurements in proton fields are perturbed by the volume effect originating from geometrical volume-averaging within the extended detector’s sensitive volume and density perturbations by non-water equivalent detector components. Detector specific lateral dose response functions K(x) can be used to characterize the volume effect within the framework of a mathematical convolution model, where K(x) is the convolution kernel transforming the true dose profile D(x) into the measured signal profile of a detector M(x). The aim of this work is to investigate K(x) for detectors in proton beams. Approach. The K(x) for five detectors were determined by iterative deconvolution of measurements of D(x) and M(x) profiles at 2 cm water equivalent depth of a narrow 150 MeV proton beam. Monte Carlo simulations were carried out for two selected detectors to investigate a potential energy dependence, and to study the contribution of volume-averaging and density perturbation to the volume effect. Main results. The Monte Carlo simulated and experimentally determined K(x) agree within 2.1% of the maximum value. Further simulations demonstrate that the main contribution to the volume effect is volume-averaging. The results indicate that an energy or depth dependence of K(x) is almost negligible in proton beams. While the signal reduction from a Semiflex 3D ionization chamber in the center of a gaussian shaped field with 2 mm sigma is 32% for photons, it is 15% for protons. When measuring the field with a microDiamond the trend is less pronounced and reversed with a signal reduction for protons of 3.9% and photons of 1.9%. Significance. The determined K(x) can be applied to characterize the influence of the volume effect on detectors measured signal profiles at all clinical proton energies and measurement depths. The functions can be used to derive the actual dose distribution from point detector measurements.
Monitoring of two-dimensional tungsten concentration profiles on the HL-2A tokamak
Authors: Wang Tianbo , Li Bingli , Gao Jinming , Zhong Wulyu , Li Hui , Yang Zengchen , Min Jiang , Fang Kairui , Xiao Guoliang , Zhu Yiren , Han Mingkun , Xu Jianqiang , Mazon Didier , Verdoolaege Geert , Zhang Kai , Dong Chunfeng , Zhang Yipo , Zou Xiao-Lan
Published: June 2022

In this article, we demonstrate the inference of two-dimensional tungsten concentration profiles in tokamak plasmas, using Gaussian process tomography applied to bolometry and assuming a specific model for the tungsten cooling factor. In ITER, tungsten has been selected for divertor material due to its low tritium retention and ability to handle large heat and particle flux loads. On the other hand, this will cause tungsten impurities to enter the bulk plasma through various plasma-wall interaction processes. Therefore, a detailed understanding of tungsten impurity transport and active control of the impurity transport in tokamaks is crucial. The computational complexity of the method described in their article

O

n
2

m

compares favorably to a simple least-squares approach

O

n
3

, n represents the number of pixels and m the number of measurement channels, hence bringing real-time tungsten profile monitoring within reach (<10 ms repetition time). The feasibility study of this method has been demonstrated here to a discharge in HL-2A for observing the entire process of tungsten impurities entering the bulk plasma from the scrape-off layer area, tungsten pump-out by edge-localized modes, as well as the formation of a poloidally asymmetric tungsten distribution.
Analysis of the buffer trap-induced kink effect in AlGaN/GaN HEMT on SiC substrate
Authors: Ciou Fong-Min , Chen Po-Hsun , Chang Ting-Chang , Lin Yu-Shan , Jin Fu-Yuan , Hsu Jui-Tse , Lin Jia-Hong , Chang Kai-Chun , Kuo Ting-Tzu , Chen Kuan-Hsu
Published: June 2022

In this study, the mechanism of the kink effect observed during the switching operation in AlGaN/GaN high-electron-mobility transistors is thoroughly analyzed. The I
D–V
G characteristics show a drop in I
D and a positive shift in threshold voltage (V
T) when the kink effect occurs. Then, using Silvaco software to simulate the trap position, the negative buffer trap induces the V
T to shift positively, dominating the decrease in the I
D. By using a long-term DC stress test under bias conditions, where the kink phenomenon occurred, the V
T will shift in the negative direction, which shows that the hole generated by impact ionization (II) plays a key role in the kink effect. Furthermore, the I
D–V
G after kink-effect stress does not respond to red, green or blue light illumination but does to UV light, which means that electron de-trapping cannot restore the V
T shift caused by the kink effect. Finally, the complete mechanism of the kink effect is provided. The recombination of hot holes generated by II with the electron trapped in buffer defects is the main mechanism for the kink phenomenon.
Static and dynamic transport properties of multi-terminal, multi-junction microSQUIDs realized with Nb/HfTi/Nb Josephson junctions
Authors: Wolter S , Linek J , Weimann T , Koelle D , Kleiner R , Kieler O
Published: June 2022

The progressive miniaturization of superconducting quantum interference devices (SQUIDs) used, e.g. for magnetic imaging on the nanoscale or for the detection of the magnetic states of individual magnetic nanoparticles causes increasing problems in realizing a proper flux-bias scheme for reading out the device. To overcome the problem, a multi-terminal, multi-junction layout has been proposed and realized recently for the SQUID-on-tip configuration, which uses constriction-type Josephson junctions (JJ). This geometry is also interesting for SQUIDs based on overdamped superconductor—normal metal—superconductor (SNS) JJ. We fabricated four-terminal, four-junction SQUIDs based on a trilayer Nb/HfTi/Nb process and study their static and dynamic transport properties in close comparison with numerical simulations based on the resistively and capacitively shunted junction model. Simulations and measurements are in very good agreement. However, there are large differences to the transport properties of conventional two-junction SQUIDs, including unusual phase-locked and chaotic dynamic states which we describe in detail. We further extract the current-phase relation of our SNS junctions, which turns out to be purely sinusoidal within the experimental error bars.
Searching for dark-matter waves with PPTA and QUIJOTE pulsar polarimetry
Authors: Castillo Andrés , Martin-Camalich Jorge , Terol-Calvo Jorge , Blas Diego , Caputo Andrea , Génova Santos Ricardo Tanausú , Sberna Laura , Peel Michael , Rubiño-Martín Jose Alberto
Published: June 2022

The polarization of photons emitted by astrophysical sources might be altered as they travel through a
dark matter medium composed of ultra light axion-like particles (ALPs). In particular, the coherent oscillations of the ALP background in the galactic halo induce a periodic change on the
polarization of the electromagnetic radiation emitted by local sources such as pulsars. Building up on previous works, we develop a new, more robust, analysis based on the generalised Lomb-Scargle periodogram to search for this periodic signal in the emission of the Crab supernova remnant observed by the QUIJOTE MFI instrument and 20 Galactic pulsars from the Parkes Pulsar Timing Array (PPTA) project. We also carefully take into account the stochastic nature of the axion field, an effect often overlooked in previous works.
This refined analysis leads to the strongest limits on the axion-photon coupling
for a wide range of dark matter masses spanning 10-23 eV ≲ ma
≲ 10-19 eV. Finally, we survey possible optimal targets and the potential sensitivity to axionic dark-matter in this mass range that could be achieved using pulsar polarimetry in the future.
Double inflation via non-minimally coupled spectator
Authors: Kubota Mio , Oda Kin-ya , Rusak Stanislav , Takahashi Tomo
Published: June 2022

We argue that double inflation may occur when a spectator field is non-minimally coupled to gravity. As a concrete example, we study a two-field inflationary model where the initial spectator field is non-minimally coupled to gravity while the initial inflaton field is minimally coupled. The non-minimal coupling results in the growth of the spectator field which, in turn, drives the second stage of inflation in a significant region of parameter space. The isocurvature fluctuations originating from the spectator field source adiabatic ones, and hence the spectator non-minimal coupling can modify the inflationary predictions for the spectral index and the tensor-to-scalar ratio even though the initial inflaton field is minimally coupled to gravity. We explicitly show that quadratic chaotic inflation can become viable by the introduction of the spectator non-minimal coupling.
Neural net modeling of equilibria in NSTX-U
Authors: Wai J.T. , Boyer M.D. , Kolemen E.
Published: June 2022

Neural networks (NNs) offer a path towards synthesizing and interpreting data on faster timescales than traditional physics-informed computational models. In this work we develop two NNs relevant to equilibrium and shape control modeling, which are part of a suite of tools being developed for the National Spherical Torus Experiment-Upgrade for fast prediction, optimization, and visualization of plasma scenarios. The networks include Eqnet, a free-boundary equilibrium solver trained on the EFIT01 (Equilibrium FITtting 01) reconstruction algorithm, and Pertnet, which is trained on the Gspert code and predicts the non-rigid plasma response, a nonlinear term that arises in shape control modeling. The NNs are trained with different combinations of inputs and outputs in order to offer flexibility in use cases. In particular, Eqnet can use magnetic diagnostics as inputs and act as an EFIT-like reconstruction algorithm, or, by using pressure and current profile information the NN can act as a forward Grad–Shafranov equilibrium solver. This forward-mode version is envisioned to be implemented in the suite of tools for simulation of plasma scenarios. The reconstruction-mode version gives some performance improvements compared to the online reconstruction code real-time EFIT, especially when vessel eddy currents are significant. We report strong performance for all NNs indicating that the models could reliably be used within closed-loop simulations or other applications. Some limitations are discussed.
Aceh Local Dolomite Modified by Alkali Metals as a Low-Cost Solid Inorganic Catalyst for Biodiesel Synthesis
Authors: Ramli Muliadi , Maisarah Minnati Rana , Saidi Nurdin , Murniana  , Idris Nasrullah
Published: June 2022

Solid inorganic-based catalyst which mainly contains calcium oxide and magnesium oxide has been successfully prepared from local Aceh dolomite minerals. The calcination process of dolomite particles (150 μm) in the air environment for 4 hours changed those calcium and magnesium carbonates compounds into their oxide form, which are subsequently referred to as inorganic oxides. Furthermore, the calcined local dolomite has been chemically modified using alkaline metal precursors (lithium, sodium and cesium precursors). Physicochemical investigation on the modified dolomite indicated that introduction of lithium metal on modified dolomite surface has a positive impact on increasing the number and strength of basic sites on the catalyst. The modified catalyst had proved its catalytic activity for biodiesel synthesis with the yield values of 82;78;51 respectively.