bluuebunny/crossref_metadata_2025 huggingface dataset:
I2-induced cascade cyclization and dearomatization of indoles for the highly efficient synthesis of iodinated and vinylic spiroindolenines
Authors: Wei Xiaohui , Liang Xuewu , Li Yazhou , Liu Qi , Liu Xuyi , Zhou Yu , Liu Hong
Published: November 2021

The spiroindolenine framework is a privileged heterocyclic motif and is widely present in numerous indole alkaloids.
One-pot biocatalytic synthesis of nylon monomers from cyclohexanol usingEscherichia coli-based concurrent cascade consortia
Authors: Sarak Sharad , Khobragade Taresh P. , Jeon Hyunwoo , Pagar Amol D. , Giri Pritam , Lee Somin , Yun Hyungdon
Published: November 2021

We developed a multienzyme biocatalytic cascade with high atom efficiency and a self-sufficient redox network for the synthesis of nylon monomers without adding auxiliary enzymes to recycle cofactors.
Pyromellitic diamide–diacid bridged mesoporous organosilica nanospheres with controllable morphologies: a novel PMO for the facile and expeditious synthesis of imidazole derivatives
Authors: Valiey Ehsan , Dekamin Mohammad G.
Published: November 2021

Novel pyromellitic diamide–diacid bridged mesoporous organosilica nanospheres with controllable morphologies and acidic centers were designed and prepared through a convenient method by altering the addition sequence of precursors, solvent, and aging time.
Genome mining methods to discover bioactive natural products
Authors: Bauman Katherine D. , Butler Keelie S. , Moore Bradley S. , Chekan Jonathan R.
Published: November 2021

The continual growth of publicly available genomic databases offers researchers unprecedented bioinformatic opportunities. This review examines different approaches to mining genomic data for the targeted discovery of bioactive natural products.
Long-term stability and tree-ring oxidation of WSe2 using phase-contrast AFM
Authors: Gammelgaard Lene , Whelan Patrick R. , Booth Timothy J. , Bøggild Peter
Published: November 2021

Phase contrast atomic force microscopy shows how tungsten diselenide oxidation evolves into complex patterns over 75 months, following season-dependent changes in the laboratory environment, in analogy with tree-rings in nature.
Engineering oxygen vacancies in CoO@Co3O4/C nanocomposites for enhanced electrochemical performances
Authors: Chu Hongqi , Zhang Dan , Feng Panpan , Gu Yulong , Chen Pen , Pan Kai , Xie Haijiao , Yang Min
Published: November 2021

The build-in electric field derived from oxygen vacancy in Co-based electrocatalysts have become important for energy storage and conversion.
Catalyst-free formal [3 + 2] cycloaddition of stabilized N,N-cyclic azomethine imines to 3-nitrobenzofurans and 3-nitro-4H-chromenes: access to heteroannulated pyrazolo[1,2-a]pyrazoles
Authors: Osipov Dmitry V. , Korzhenko Kirill S. , Rashchepkina Daria A. , Artemenko Alina A. , Demidov Oleg P. , Shiryaev Vadim A. , Osyanin Vitaly A.
Published: November 2021

We have studied the [3 + 2]-cycloaddition of various N,N-cyclic azomethine imines to 3-nitrobenzofurans.
New heteroanalogs of tricyclic ascidian alkaloids: synthesis and biological activity
Authors: Goryaeva Marina V. , Kushch Svetlana O. , Burgart Yanina V. , Ezhikova Marina A. , Kodess Mikhail I. , Slepukhin Pavel A. , Triandafilova Galina A. , Krasnykh Olga P. , Yakovleva Ekaterina I. , Zarubaev Vladimir V. , Sinegubova Ekaterina O. , Esaulkova Iana L. , Shtro Anna A. , Galochkina Anastasia V. , Nikolaeva Yulia V. , Saloutin Victor I.
Published: November 2021

Heteroanalogs of ascidian alkaloids have been synthesized.
Performance and mechanism of conductive magnetite particle-enhanced excess sludge anaerobic digestion for biogas recovery
Authors: Kang Xiaorong , Liu Yali
Published: November 2021

Magnetite particles were applied to excess sludge anaerobic digestion. The methane production and sludge reduction were related to magnetite particle dosage, and the Methanosaeta and Methanoregula involved in the electron transfer were enriched.
Does electrophilic activation of nitroalkanes in polyphosphoric acid involve formation of nitrile oxides?
Authors: Aksenov Alexander V. , Aksenov Nicolai A. , Kirilov Nikita K. , Skomorokhov Anton A. , Aksenov Dmitrii A. , Kurenkov Igor A. , Sorokina Elena A. , Nobi Mezvah A. , Rubin Michael
Published: November 2021

The mechanistic rationale involving activation of nitroalkanes towards interaction with nucleophilic reagents in the presence of polyphosphoric acid (PPA) was re-evaluated. Could nitrile oxide moieties be formed during this process?
Mapping the effect of geometry on the radiative rate in core/shell QDs: core size dictates the conduction band offset
Authors: Hoffman Maxwell P. , Lee Autumn Y. , Nagelj Nejc , Lee Youjin V. , Olshansky Jacob H.
Published: November 2021

Predicting the radiative rate in CdSe/CdS core/shell quantum dots is made possible by using a core-size-dependent conduction band offset.
Current status and future directions of self-assembled block copolymer membranes for molecular separations
Authors: Lang Chao , Kumar Manish , Hickey Robert J.
Published: November 2021

Block copolymer separation membranes are energy efficient alternatives to thermal processes but are limited to nanometer ranges. Here, the review discusses synthetic and self-assembly strategies to overcome current constraints and advance the field.
A strategy towards melanin-based functional material: rGO and sulfonated melanin composites
Authors: Bregadiolli Bruna Andressa , Paulin João Vitor , Albano Luiz Gustavo Simão , Martins Lucas Michelão , de Camargo Davi Henrique Starnini , da Silva-Filho Luiz Carlos , Bufon Carlos Cesar Bof , Graeff Carlos Frederico de Oliveira
Published: November 2021

Composites of sulfonated melanin with reduced graphene oxide were synthesized in different concentrations. The new materials were structurally, optically, and electrically characterized to evaluate the effect of rGO on the material properties.
High-dose dexamethasone injection disordered metabolism and multiple protein kinases expression in the mouse kidney
Authors: Zhang Zaikuan , Ran Yingchun , Xu Lei , Pan Zheng , Xie Yajun
Published: November 2021

Glucocorticoids (GCs) have been widely used in clinical treatment as anti-inflammatory, anti-shock and immunosuppressive medicines. However, the effect of excessive GCs on immune response and metabolism of kidney remains unclear. Here, we profiled the gene expression of kidney from mice with high-dose dexamethasone (DEX) treatment. A total of 1193 differentially expressed genes (DEGs) were screened in DEX treatment group compared with the saline group, including 715 down- regulated and 478 up-regulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of these DEGs showed extracellular matrix (ECM)–receptor interaction, cell adhesion molecules signaling pathway were significantly enriched, and that the vast majority of DEGs were involved in monocarboxylic acid metabolism, leukocyte cell–cell adhesion and fatty acid metabolism. Gene set enrichment analysis (GSEA) revealed that DEGs were strongly associated with immune-response and cell adhesion gene sets, such as Fc γ R-mediated phagocytosis, leukocyte transendothelial migration, T-cell receptor signaling pathway, cell adhesion, ECM–receptor interaction and focal adhesion-associated pathways. KEGG pathway analysis of differentially expressed kinases (DEKs) showed T-cell receptor and forkhead box class O signaling pathway were enriched. Furthermore, we found multiple protein kinases expression were dysregulated greatly after dexamethasone treatment, including classical effector of GCs stimulation-serum and GC-regulated kinase. These protein kinases are involved in multiple signaling pathways in mice kidney, such as mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. We profiled the gene expression of the kidney from high-dose dexamethasone-treated mice and provided important information for further study the mechanism of side effects of GCs in clinical therapy.
Objective Laryngoscopic Measures From Older Patients With Voice Complaints and Signs of Aging
Authors: Stager Sheila V. , Gupta Simran , Amdur Richard , Bielamowicz Steven A.
Published: November 2021

Purpose:

The purpose of this study was to use objective measures of glottal gap, bowing, and supraglottic compression from selected images of laryngoscopic examinations from adults over 60 years of age with voice complaints and signs of aging to test current hypotheses on whether degree of severity impacts treatment recommendations and potential follow-through with treatment.

Method:

Records from 108 individuals 60 years or older with voice complaints and signs of aging were reviewed. Three objective measures (normalized glottal gap area [NGGA], total bowing index, and normalized true vocal fold width) were derived. Each measure was subsequently divided into three categories by severity: absence, small degree, or large degree. Nonparametric statistics tested associations between severity and treatment recommendations as well as potential follow-through.

Results:

Noninvasive treatments (observation/voice therapy) were marginally associated with no glottal gap (p= .09). More invasive treatments (injection/bilateral thyroplasty) were associated with glottal gaps being present (p= .026), but bilateral thyroplasty recommendations were not significantly associated with the largest gaps. Treatment modalities were not characterized by specific severity categories for any of the objective measures. No significant differences were found for any of the three objective measures between those who followed through with recommended treatment and those who did not.

Discussion:

Results demonstrated some support for current hypotheses on how degrees of severity of objective measures relate to treatment recommendations. Of the three measures, NGGA appears to be more informative regarding treatment recommendations and follow-through, but due to low power, larger sample sizes are needed to confirm clinical relevance.
Event-Related Potentials Elicited by Phonetic Errors Differentiate Children With Speech Sound Disorder and Typically Developing Peers
Authors: Gerwin Katelyn L. , Brosseau-Lapré Françoise , Weber Christine
Published: November 2021

Purpose:

A growing body of research suggests that a deficit in speech perception abilities contributes to the development of speech sound disorder (SSD). However, little work has been done to characterize the neurophysiological processes indexing speech perception deficits in this population. The primary aim of this study was to compare the neural activity underlying speech perception in young children with SSD and with typical development (TD).

Method:

Twenty-eight children ages 4;1–6;0 (years;months) participated in this study. Event-related potentials (ERPs) were recorded while children completed a speech perception task that included phonetic (speech sound) and lexical (meaning) matches and mismatches. Groups were compared on their judgment accuracy for matches and mismatches as well as the mean amplitude of the phonological mapping negativity (PMN) and N400 ERP components.

Results:

Children with SSD demonstrated lower judgment accuracy across the phonetic and lexical conditions compared to peers with TD. The ERPs elicited by lexical matches and mismatches did not distinguish the groups. However, in the phonetic condition, the SSD group exhibited a more consistent left-lateralized PMN effect and a delayed N400 effect over frontal sites compared to the TD group.

Conclusions:

These findings provide some of the first evidence of a delay in the neurophysiological processing of phonological information for young children with SSD compared to their peers with TD. This delay was not present for the processing of lexical information, indicating a unique difference between children with SSD and with TD related to speech perception of phonetic errors.

Supplemental Material

https://doi.org/10.23641/asha.16915579
Deep transfer learning for blended source identification in galaxy survey data
Authors: Farrens S. , Lacan A. , Guinot A. , Vitorelli A. Z.
Published: November 2021

We present BLENDHUNTER, a proof-of-concept deep-transfer-learning-based approach for the automated and robust identification of blended sources in galaxy survey data. We take the VGG-16 network with pre-trained convolutional layers and train the fully connected layers on parametric models of COSMOS images. We test the efficacy of the transfer learning by taking the weights learned on the parametric models and using them to identify blends in more realistic Canada-France Imaging Survey (CFIS)-like images. We compare the performance of this method to SEP (a Python implementation of SEXTRACTOR) as a function of noise levels and the separation between sources. We find that BLENDHUNTERoutperforms SEP by ∼15% in terms of classification accuracy for close blends (< 10 pixel separation between sources) regardless of the noise level used for training. Additionally, the method provides consistent results to SEP for distant blends (≥10 pixel separation between sources) provided the network is trained on data with noise that has a relatively close standard deviation to that of the target images. The code and data have been made publicly available to ensure the reproducibility of the results.
ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT)
Authors: Garufi A. , Podio L. , Codella C. , Segura-Cox D. , Vander Donckt M. , Mercimek S. , Bacciotti F. , Fedele D. , Kasper M. , Pineda J. E. , Humphreys E. , Testi L.
Published: November 2021

Planet-forming disks are not isolated systems. Their interaction with the surrounding medium affects their mass budget and chemical content. In the context of the ALMA-DOT program, we obtained high-resolution maps of assorted lines from six disks that are still partly embedded in their natal envelope. In this work, we examine the SO and SO2emission that is detected from four sources: DG Tau, HL Tau, IRAS 04302+2247, and T Tau. The comparison with CO, HCO+, and CS maps reveals that the SO and SO2emission originates at the intersection between extended streamers and the planet-forming disk. Two targets, DG Tau and HL Tau, offer clear cases of inflowing material inducing an accretion shock on the disk material. The measured rotational temperatures and radial velocities are consistent with this view. In contrast to younger Class 0 sources, these shocks are confined to the specific disk region impacted by the streamer. In HL Tau, the known accreting streamer induces a shock in the disk outskirts, and the released SO and SO2molecules spiral toward the star in a few hundred years. These results suggest that shocks induced by late accreting material may be common in the disks of young star-forming regions with possible consequences for the chemical composition and mass content of the disk. They also highlight the importance of SO and SO2line observations in probing accretion shocks from a larger sample.
H I mapping of the Leo Triplet
Authors: Wu Gang , Martínez-Delgado David , Henkel Christian , Kroupa Pavel , Walter Fabian , Krieger Nico , Bolatto Alberto D. , Robishaw Timothy , Simon Joshua D. , Ibáñez Pérez Álvaro , Menten Karl M. , Esimbek Jarken
Published: November 2021

A fully sampled and hitherto highest resolution and sensitivity observation of neutral hydrogen (H I) in the Leo Triplet (NGC 3628, M 65/NGC 3623, and M 66/NGC 3627) reveals six H I structures beyond the three galaxies. We present detailed results of the morphologies and kinematics of these structures, which can be used for future simulations. In particular, we detect a two-arm structure in the plume of NGC 3628 for the first time, which can be explained by a tidal interaction model. The optical counterpart of the plume is mainly associated with the southern arm. The connecting part (base) of the plume (directed eastward) with NGC 3628 is located at the blueshifted (western) side of NGC 3628. Two bases appear to be associated with the two arms of the plume. A clump with a reversed velocity gradient (relative to the velocity gradient of M 66) and a newly detected tail, that is to say M 66SE, is found in the southeast of M 66. We suspect that M 66SE represents gas from NGC 3628, which was captured by M 66 in the recent interaction between the two galaxies. Meanwhile gas is falling toward M 66, resulting in features previously observed in the southeastern part of M 66, such as large line widths and double peaks. An upside-down “Y”-shaped H I gas component (M 65S) is detected in the south of M 65, which suggests that M 65 may also have been involved in the interaction. We strongly encourage modern hydrodynamical simulations of this interacting group of galaxies to reveal the origin of the gaseous debris surrounding all three galaxies.
OGHReS: Large-scale filaments in the outer Galaxy
Authors: Colombo D. , König C. , Urquhart J. S. , Wyrowski F. , Mattern M. , Menten K. M. , Lee M.-Y. , Brand J. , Wienen M. , Mazumdar P. , Schuller F. , Leurini S.
Published: November 2021

Filaments are a ubiquitous morphological feature of the molecular interstellar medium and are identified as sites of star formation. In recent years, more than 100 large-scale filaments (with a length > 10 pc) have been observed in the inner Milky Way. As they appear linked to Galactic dynamics, studying those structures represents an opportunity to link kiloparsec-scale phenomena to the physics of star formation, which operates on much smaller scales. In this Letter, we use newly acquired Outer Galaxy High Resolution Survey (OGHReS) 12CO(2-1) data to demonstrate that a significant number of large-scale filaments are present in the outer Galaxy as well. The 37 filaments identified appear tightly associated with inter-arm regions. In addition, their masses and linear masses are, on average, one order of magnitude lower than similar-sized molecular filaments located in the inner Galaxy, showing that Milky Way dynamics is able to create very elongated features in spite of the lower gas supply in the Galactic outskirts.
Turbulent magnetic fields in the merging galaxy cluster MACS J0717.5+3745
Authors: Rajpurohit K. , Hoeft M. , Wittor D. , van Weeren R. J. , Vazza F. , Rudnick L. , Rajpurohit S. , Forman W. R. , Riseley C. J. , Brienza M. , Bonafede A. , Rajpurohit A. S. , Domínguez-Fernández P. , Eilek J. , Bonnassieux E. , Brüggen M. , Loi F. , Röttgering H. J. A. , Drabent A. , Locatelli N. , Botteon A. , Brunetti G. , Clarke T. E.
Published: November 2021

We present wideband (1 − 6.5 GHz) polarimetric observations, obtained with the Karl G. Jansky Very Large Array, of the merging galaxy cluster MACS J0717.5+3745, which hosts one of the most complex known radio relic and halo systems. We used both rotation measure synthesis and QU-fitting to find a reasonable agreement of the results obtained with these methods, particularly when the Faraday distribution is simple and the depolarization is mild. The relic is highly polarized over its entire length (850 kpc), reaching a fractional polarization > 30% in some regions. We also observe a strong wavelength-dependent depolarization for some regions of the relic. The northern part of the relic shows a complex Faraday distribution, suggesting that this region is located in or behind the intracluster medium (ICM). Conversely, the southern part of the relic shows a rotation measure very close to the Galactic foreground, with a rather low Faraday dispersion, indicating very little magnetoionic material intervening along the line of sight. Based on a spatially resolved polarization analysis, we find that the scatter of Faraday depths is correlated with the depolarization, indicating that the tangled magnetic field in the ICM causes the depolarization. We conclude that the ICM magnetic field could be highly turbulent. At the position of a well known narrow-angle-tailed galaxy (NAT), we find evidence of two components that are clearly separated in the Faraday space. The high Faraday dispersion component seems to be associated with the NAT, suggesting the NAT is embedded in the ICM while the southern part of the relic lies in front of it. If true, this implies that the relic and this radio galaxy are not necessarily physically connected and, thus, the relic may, in fact, not be powered by the shock re-acceleration of fossil electrons from the NAT. The magnetic field orientation follows the relic structure indicating a well-ordered magnetic field. We also detected polarized emission in the halo region; however, the absence of significant Faraday rotation and a low value of Faraday dispersion suggests the polarized emission that was previously considered as the part of the halo does, in fact, originate from the shock(s).
On the role of numerical viscosity in the study of the local limit of nonlocal conservation laws
Authors: Colombo Maria , Crippa Gianluca , Graff Marie , Spinolo Laura V.
Published: November 2021

We deal with the numerical investigation of the local limit of nonlocal conservation laws. Previous numerical experiments seem to suggest that the solutions of the nonlocal problems converge to the entropy admissible solution of the conservation law in the singular local limit. However, recent analytical results state that (i) in general convergence does not hold because one can exhibit counterexamples; (ii) convergence can be recovered provided viscosity is added to both the local and the nonlocal equations. Motivated by these analytical results, we investigate the role of numerical viscosity in the numerical study of the local limit of nonlocal conservation laws. In particular, we show that Lax–Friedrichs type schemes may provide the wrong intuition and erroneously suggest that the solutions of the nonlocal problems converge to the entropy admissible solution of the conservation law in cases where this is ruled out by analytical results. We also test Godunov type schemes, less affected by numerical viscosity, and show that in some cases they provide an intuition more in accordance with the analytical results.
Reactions of 1-Trifluoromethylprop-2-yne 1-Iminium Salts with Nitroanilines: Synthesis of 4-Trifluoromethylnitroquinolines and 1,2,3-Trisubstituted 5-Trifluoromethylpyrroles
Authors: Maas Gerhard , Seitz Bianca , Schneider Thomas , Majstorovic Nikola , Fleischmann Maximilian
Published: November 2021

A variety of 4-trifluoromethylquinolines bearing an aryl (or cyclopropyl, tert-butyl, trimethylsilyl) group at C-2 and a nitro group at ring position 6, 7 or 8 have been prepared in good to high yields from 3-substituted 1-(trifluoromethyl)prop-2-yne 1-iminium triflate salts and o-, m- or p-nitroaniline. These reactions include an aza-Michael reaction at room temperature followed by an intramolecular electrophilic aromatic substitution step, which requires additional thermal activation in most cases. In contrast, the conjugate addition of 2,4-dinitroanilines at the acetylenic iminium ions proceeds much more slowly and some of the adducts can be converted thermally into 2-(2,4-dinitrophenyl)-5-trifluoromethylpyrroles. Analogously, 2-(4-pyridyl)-5-trifluoromethylpyrroles were obtained from 3-aryl-1-(trifluoromethyl)propyn­iminium salts and 4-aminopyridinium triflate. A novel variation of the Truce–Smiles rearrangement is probably involved in the formation of these pyrroles.
Striations in helicon-type argon plasma
Authors: Zhu Wanying , Cui Ruilin , He Feng , Wang Yueqing , Ouyang Jiting
Published: November 2021

In this paper, two types of stationary striations appearing in an argon helicon plasma source are presented. The formation and features of the striations were investigated experimentally under different conditions, including RF power, gas pressure, and external magnetic field. The results show that the striation spacing decreases as the gas pressure increases but does not change significantly along with the magnetic field and the RF power. It is suggested that these striations are strongly related to the non-local effect of electron kinetics in the plasma channel with a weak electric field. The different pressures in downstream and antenna regions will lead to different types of striations in an argon helicon plasma source.
Imaging buried objects with the hard/soft x-ray photoemission electron microscope
Authors: Liu Chia-Chi , Huang Yen , Chuang Tzu-Hung , Lin Deng-Sung , Wei Der-Hsin
Published: November 2021

We apply charged-particle simulation to determine the constraints imposed additionally on the photoemission electron microscope (PEEM) when x rays are applied to image buried objects. PEEM initiates its image acquisition by reading the electron-emission profile on the specimen surface, but the profile is not invariant if the electrons originate from a buried object. In this work, we show that, other than the anticipated intensity reduction, the electron-emission profile projected from a buried object displays a blurrier edge for a deeper burial, whereas the distribution of an emission angle becomes narrower for electrons carrying greater kinetic energy. The burial not only redefines the objects seen by PEEM but also introduces additional depth and energy dependence to the resulted images. We demonstrate that inserting a contrast aperture in the PEEM lens can improve the image quality and ease the burial dependence.
A photoionized pulsed low-energy ion beam source for quantum state-to-state crossed ion-molecule scattering
Authors: Zhang Guodong , Guan Lichang , Cheng Min , Gao Hong
Published: November 2021

Here, we report the design and test of a pulsed low-energy ion beam source for crossed ion-molecule scattering studies. The ions are produced by laser photoionization based methods and thus can be prepared in well-defined quantum states. By using the combination of a double Einzel lenses setup and a specially designed shielding tube, a well spatially confined ion bunch with tunable kinetic energies in the range of 1.0–5.0 eV and typical spreads of ∼150 meV (full width at half maximum) can be formed in the center of a velocity-map imaging (VMI) stack. By combining it with a recently constructed three-dimensional VMI system, the present apparatus is readily available for quantum state-to-state crossed ion-molecule scattering studies.
Photodissociation dynamics of CF3CHO: C–C bond cleavage
Authors: Campbell Jyoti S. , Nauta Klaas , Kable Scott H. , Hansen Christopher S.
Published: November 2021

The photodissociation dynamics of jet-cooled trifluoroacetaldehyde (CF3CHO) into radical products, CF3 + HCO, was explored using velocity mapped ion imaging over the wavelength range 297.5 nm ≤λ≤ 342.8 nm (33 613–29 172 cm−1) covering the entire section of the absorption spectrum accessible with solar actinic wavelengths at the ground level. After initial excitation to the first excited singlet state, S1, the radical dissociation proceeds largely via the first excited triplet state, T1, at excitation energies above the T1 barrier. By combining velocity-mapped ion imaging with high-level theory, we place this barrier at 368.3 ± 2.4 kJ mol−1 (30 780 ± 200 cm−1). After exciting to S1 at energies below this barrier, the dissociation proceeds exclusively via the ground electronic state, S0. The dissociation threshold is determined to be 335.7 ± 1.8 kJ mol−1 (28 060 ± 150 cm−1). Using laser-induced fluorescence spectroscopy, the origin of the S1 ← S0 transition is assigned at 28 903 cm−1. The S0 dissociation channel is active at the S1 origin, but the yield significantly increases above 29 100 cm−1 due to enhanced intersystem crossing or internal conversion.
Detection of chirality-induced spin polarization over millimeters in polycrystalline bulk samples of chiral disilicides NbSi2 and TaSi2
Authors: Shishido Hiroaki , Sakai Rei , Hosaka Yuta , Togawa Yoshihiko
Published: November 2021

We report that spin polarization occurs over millimeters in polycrystalline bulk samples of chiral disilicide NbSi2 and TaSi2. As previously demonstrated in the experiments using single crystals of NbSi2 and TaSi2, electrical transport measurements allow detection of direct and inverse signals associated with the chirality-induced spin polarization even in the chiral polycrystals. Spin polarization signals also appear in nonlocal measurements, in which charge current flows only in the area millimeters away from the detection electrode. These data mean that the spin polarization phenomena occur regardless of the presence of crystalline grains in the polycrystals, indicating a robustness and resilience of the chirality-induced spin polarization. On the basis of the experimental data, we found that the sum rule holds for the spin transport signals. A distribution of handedness over the samples was determined on average in the polycrystals. While the mechanism of preserving the spin polarization over millimeters remains to be clarified, the present study may open up prospects of spin control and manipulation over macroscopic length scales using chiral materials.
Soil formation, nutrient supply and ecosystem productivity on basaltic lava vs rhyolitic pumice on Alcedo Volcano, Galápagos
Authors: Zehetner Franz , Jäger Heinke , Keiblinger Katharina M. , Dinter Tamara C. , Candra I. Nyoman , Bajraktarevic Armin , Puschenreiter Markus , Gerzabek Martin H.
Published: November 2021

Context Rock type may exert strong control on pedogenesis and resulting soil characteristics. Little is known on how different volcanic lithologies influence soil formation and nutrient supply and thereby affect ecosystem productivity in volcanic landscapes. Aims The aim of this study was to investigate lithologic control on the mentioned properties and processes. Methods We conducted a side-by-side comparison of two contrasting sites in close proximity on Alcedo Volcano, Galápagos, one on basaltic lava and the other on rhyolitic pumice. Key results The lava site was covered by lush, stratified woodland, whereas the pumice site was covered by grassland with only few plant species. The soil on lava was a Leptosol, whereas on pumice, an Andosol had formed. Both soils had similar pH (6.0–6.5 in H2O), but the soil organic carbon stocks at the lava site were almost twice as high as at the pumice site (13.1 ± 1.6 vs 7.6 ± 1.3 kg m−2 to 25 cm depth). The soil at the pumice site had considerably lower levels of Mehlich-3-extractable P, Ca, Mg, Cu, Zn and B. Soil microbes at the pumice site had lower biomass P (and a higher C:P ratio) and excreted more phosphatase. The grass biomass here also showed lower (and deficient) levels of P and other nutrients compared to the lava site. Conclusions and implications The contrasting lithologies and their bearings on soil formation and nutrient availability diversify the aboveground and belowground ecosystems and favour the development of distinct ecological niches in close proximity.
Bach1 derepression is neuroprotective in a mouse model of Parkinson’s disease
Authors: Ahuja Manuj , Ammal Kaidery Navneet , Attucks Otis C. , McDade Erin , Hushpulian Dmitry M. , Gaisin Arsen , Gaisina Irina , Ahn Young Hoon , Nikulin Sergey , Poloznikov Andrey , Gazaryan Irina , Yamamoto Masayuki , Matsumoto Mitsuyo , Igarashi Kazuhiko , Sharma Sudarshana M. , Thomas Bobby
Published: November 2021

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder characterized by the loss of nigrostriatal dopaminergic neurons. Mounting evidence suggests that Nrf2 is a promising target for neuroprotective interventions in PD. However, electrophilic chemical properties of the canonical Nrf2-based drugs cause irreversible alkylation of cysteine residues on cellular proteins resulting in side effects. Bach1 is a known transcriptional repressor of the Nrf2 pathway. We report that Bach1 levels are up-regulated in PD postmortem brains and preclinical models. Bach1 knockout (KO) mice were protected against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced dopaminergic neurotoxicity and associated oxidative damage and neuroinflammation. Functional genomic analysis demonstrated that the neuroprotective effects in Bach1 KO mice was due to up-regulation of Bach1-targeted pathways that are associated with both Nrf2-dependent antioxidant response element (ARE) and Nrf2-independent non-ARE genes. Using a proprietary translational technology platform, a drug library screen identified a substituted benzimidazole as a Bach1 inhibitor that was validated as a nonelectrophile. Oral administration of the Bach1 inhibitor attenuated MPTP neurotoxicity in pre- and posttreatment paradigms. Bach1 inhibitor–induced neuroprotection was associated with the up-regulation of Bach1-targeted pathways in concurrence with the results from Bach1 KO mice. Our results suggest that genetic deletion as well as pharmacologic inhibition of Bach1 by a nonelectrophilic inhibitor is a promising therapeutic approach for PD.
Time-dependent quantum harmonic oscillator: a continuous route from adiabatic to sudden changes
Authors: Martínez-Tibaduiza Daniel , Pires Luis , Farina Carlos
Published: November 2021

In this work, we give a quantitative answer to the question: how sudden or how adiabatic is a frequency change in a quantum harmonic oscillator (HO)? We do that by studying the time evolution of a HO which is initially in its fundamental state and whose time-dependent frequency is controlled by a parameter (denoted by ϵ) that can continuously tune from a totally slow process to a completely abrupt one. We extend a solution based on algebraic methods introduced recently in the literature that is very suited for numerical implementations, from the basis that diagonalizes the initial Hamiltonian to the one that diagonalizes the instantaneous Hamiltonian. Our results are in agreement with the adiabatic theorem and the comparison of the descriptions using the different bases together with the proper interpretation of this theorem allows us to clarify a common inaccuracy present in the literature. More importantly, we obtain a simple expression that relates squeezing to the transition rate and the initial and final frequencies, from which we calculate the adiabatic limit of the transition. Analysis of these results reveals a significant difference in squeezing production between enhancing or diminishing the frequency of a HO in a non-sudden way.
Combined proton–photon treatment for breast cancer
Authors: Marc Louise , Fabiano Silvia , Wahl Niklas , Linsenmeier Claudia , Lomax Antony J , Unkelbach Jan
Published: November 2021

Objective. Proton therapy remains a limited resource due to gantry size and its cost. Recently, a new design without a gantry has been suggested. It may enable combined proton–photon therapy (CPPT) in conventional bunkers and allow the widespread use of protons. In this work, we explore this concept for breast cancer. Methods. The treatment room consists of a LINAC for intensity modulated radiation therapy (IMRT), a fixed proton beamline (FBL) with beam scanning and a motorized couch for treatments in lying positions with accurate patient setup. Thereby, proton and photon beams are delivered in the same fraction. Treatment planning is performed by simultaneously optimizing IMRT and IMPT plans based on the cumulative dose. The concept is investigated for three breast cancers where the goal is to minimize mean dose to the heart and lung while delivering 40.05 Gy in 15 fractions to the PTV with a SIB of 48 Gy to the tumor bed. The probabilistic approach is applied to mitigate the sensitivity to range uncertainties. Results. CPPT is particularly advantageous for irradiating concave target volumes that wrap around a curved chest wall. There, protons may deliver dose to the peripheral and medial parts of the target volume including lymph nodes. Thereby, the mean dose in normal tissues is reduced compared to single-modality IMRT. However, tangential photon beams may treat parts of the target volume near the interface to the lung. To ensure target coverage for range undershoot in an IMPT plan, proton beams have to deliberately overshoot into the lung tissue—a problem that can be mitigated via the photon component which ensures plan conformity and robustness. Conclusion. CPPT using an FBL may represent a realistic approach to make protons available to more patients. In addition, CPPT may generally improve treatment quality compared to both single-modality proton and photon treatments.
Global plasma modeling of a magnetized high-frequency plasma source in low-pressure nitrogen and oxygen for air-breathing electric propulsion applications
Authors: Mrózek Kryštof , Dytrych Tomáš , Moliš Pavel , Dániel Vladimír , Obrusník Adam
Published: November 2021

This work presents a global plasma model of a gridded air-breathing electric propulsion concept based on magnetized high-frequency plasma operating in the pressure range of 10−3 Pa to 1 Pa. We illustrate that the global plasma model reproduces the experimental measurements of the extracted current over two orders of magnitude in pressure. Consequently, we use the model to investigate the theoretical scalability of the plasma source, finding that the plasma source performance scales reasonably well with the average absorbed power per molecule, even though this scaling factor has its limits. The global model presented in this work is a model of a specific laboratory device and, in future, it can be adapted to very low Earth orbit conditions by adjusting the boundary conditions. The model was implemented using PlasmaSolve p3s-globalmodel software and the configuration file containing all the equations is provided to the community as supplementary material.
Simulations on the rheology of dry magneto-rheological fluid under various working modes
Authors: Pei Lei , Ma Zongqiang , Ma Dongjun , Shi Xiaofeng , Pan Hao , Wang Pei , Gong Xinglong
Published: November 2021

This work studied the rheological properties and magnetorheological (MR) mechanism of dry magnetorheological fluid (MRF) under various working modes. A novel simulation method combining the discrete element method and computational fluid dynamics was developed, in which the bilateral coupling between particles and the flow field of the matrix (air) was considered. The microstructures and mechanical properties in the redispersion process, shear mode, and valve mode were systematically simulated for the first time. The results indicated that dry MRF presented superior redispersion property and response time (several μs) than liquid-based MRFs. In shear mode, the magnetic dipolar force and friction force dominated the evolution of microstructures. In valve mode, the magnetic dipolar force and viscous drag force of air became the main interactions. Magnetic particles aggregated into sturdy chain structures and hindered the airflow. The MR effect in valve mode was the pressure gradient of the matrix, which increased up to 1.08 × 105 Pa m−1 with the increasing particle volume fractions and decreased under a large inflow velocity. The best MR effect in valve mode was achieved under a magnetic field of B = 63 mT. Simulations revealed the influence of dimensionless Mn and Re number on the MR effect. The pressure gradient of the matrix was controlled by the external field and can be utilized to design a dry MRF valve for precious and transient vibration control. Simulated dimensionless shear stress in shear mode agreed well with experiments. This work will promote the development and applications of novel high-performance MRFs.
Pitch-catch UGW-based multiple damage inference: a heterogeneous graph interpretation
Authors: Zhou Lu , Chen Si-Xin , Ni Yi-Qing , Jiang Liu
Published: November 2021

Ultrasonic guided waves (UGWs) have been extensively utilized in nondestructive testing and structural health monitoring (SHM) for detection and real-time monitoring of structural defects. By implementing multiple piezoelectric sensors onto a plane of the target structure to form a sensor network, damages within the sensing range can be detected or even visualized through a pitch-catch configuration. On the other hand, deep learning (DL) techniques have recently been widely used to aid UGW-based SHM when the waveform is over complicated to extract a specific mode of interest due to irregular structure or boundary reflections. However, not too much research work has been conducted to thoroughly combine sensor networks with DL. Existing research using DL approaches is mainly used to train and interpret waveforms from isolated sensor pairs. The topological structure of sensor layout and sensor-damage relative positions are hardly considered in the data-driven process. Motivated by these concerns, this study offers a first-of-its-kind perspective to interpret UGW data collected from a sensor network by mapping the physical sensor-damage layout into a graph, in which sensors and potential damages serve as graph vertices bearing heterogenous properties upon coming to UGWs and the process of UGW transmission between sensors are encapsulated as wavelike message passing between the vertices. A novel physics-informed end-to-end graph neural network model, named as WaveNet, was exquisitely and meticulously developed. By utilizing wave information and topological structure, WaveNet enables inference of multiple damages in terms of severity and location with satisfactory accuracy, even when the waveforms are chaotic, and the sensor arrangement is different at the training and testing stages. More importantly, beyond the SHM scenario, the present study is expected to enlighten new thinking on interconnecting physical wave propagation with virtual messaging passing in neural networks.
Experimental continuous-variable quantum key distribution using a thermal source
Authors: Huang Peng , Wang Tao , Chen Rui , Wang Ping , Zhou Yingming , Zeng Guihua
Published: November 2021

Gaussian-modulated coherent-state (GMCS) continuous-variable quantum key distribution (CVQKD) protocol can allow authenticated users to share secret key with unconditional security. So far, all previous experimental implementations of GMCS CVQKD schemes are based on active modulations, i.e. amplitude and phase modulators and quantum random number generator (QRNG) are required. However, high-speed modulation with high extinction ratio and stability is challenging, which is extremely remarkable in chip-scale silicon photonic realization. While the passive-state-preparation (PSP) CVQKD scheme, which explores the intrinsic field fluctuations of a thermal source, avoids the uses of active modulations and QRNG. In this paper, we experimentally realize the intact PSP CVQKD through a realistic optical fiber channel using off-the-shelf amplified spontaneous emission source. In particular, specially designed frame synchronization method is used to build the correlation between the data measured from the two legitimate parties, and excess noise are synthetically controlled to generate secure secret keys at the metro-area distances when considering the practical and non-negligible finite-size effects under collective Gaussian attacks. Due to the avoidance of modulators and QRNG, the passive state encoding scheme provides a promising direction of applicable high-speed, chip-based and even sunlight-based CVQKD with less cost and complexity.
Dispersion of elastic waves in an inhomogenous multilayered plate over a Winkler elastic foundation with imperfect interfacial conditions
Authors: Asif Muhammad , Nawaz Rab , Nuruddeen Rahmatullah Ibrahim
Published: November 2021

This study examines the dispersion of elastic waves in a strongly inhomogeneous three-layered plate resting on a Winkler elastic foundation in the presence of imperfect interfacial conditions alongside a stress-free upper face. The propagation of elastic waves in the plate is governed by the two-dimensional anti-plane shear motion. The asymptotic technique is employed for the analysis. The exact dispersion relation and the overall cut-off frequency are determined. Within the long-wave low-frequency region, the shortened polynomial dispersion relation corresponding to the exact dispersion relation has been computed and studied for a particular material contrast. The associated one-dimensional equations of motions are also derived in approximate forms for perfect interface as a case of interest. Finally, according to the findings of this investigation, the obtained approximate equations of motions for a three-layered plate remain valid over the entire low-frequency spectrum even in presence of an elastic foundation. We also examined the variational impacts of the dimensionless Winkler elastic foundation parameter G and the interface imperfect parameter γ on the dispersion branch of harmonic waves. Furthermore, to assure the long-wave low-frequency range, the numerical simulations and graphical visualization are presented by utilizing certain physical data.
Modeling the dynamics of firms’ technological impact*
Authors: Xu Shuqi , Mariani Manuel Sebastian , Lü Linyuan
Published: November 2021

Recent studies in complexity science have uncovered temporal regularities in the dynamics of impact along scientific and other creative careers, but they did not extend the obtained insights to firms. In this paper, we show that firms’ technological impact patterns cannot be captured by the state-of-the-art dynamical models for the evolution of scientists’ research impact, such as the Q model. Therefore, we propose a time-varying returns model which integrates the empirically-observed relation between patent order and technological impact into the Q model. The proposed model can reproduce the timing pattern of firms’ highest-impact patents accurately. Our results shed light on modeling the differences behind the impact dynamics of researchers and firms.
Acoustic multipath structure in direct zone of deep water and bearing estimation of tow ship noise of towed line array
Authors: Han Zhi-Bin , Peng Zhao-Hui , Song Jun , Meng Lei , Yang Xiu-Ting , Su Bing
Published: November 2021

In the towed line array sonar system, the tow ship noise is the main factor that affects the sonar performance. Conventional noise cancelling methods assume that the noise is towards the endfire direction of the array. An acoustic experiment employing a towed line array is conducted in the western Pacific Ocean, and a strange bearing-splitting phenomenon of the tow ship noise is observed in the array. The tow ship noise is split into multiple noise signals whose bearings are distributed between 10° and 90° deviating from the endfire direction. The multiple interferences increase the difficulty in recognizing the target for the sonar operator and noise cancellation. Therefore, making the mechanism clear and putting forward the tow ship noise splitting bearing estimation method are imperative. In this paper, the acoustic multi-path structure of the tow ship in deep water is analyzed. Then it is pointed out that the bearing-splitting phenomenon is caused by the main lobe of direct rays and bottom-reflected rays, as well as several side lobes of direct rays. Meanwhile, the indistinguishability between the elevation angle and the bearing angle due to the axial symmetry of a strict horizontal line array causes the bearing to deviate from the endfire direction. Based on the theory above, a method of estimating bearing of the tow ship noise in deep water is proposed. The theoretical analysis results accord with the experimental results, which helps to identify the target and provide correct initial bearing guidance for noise cancelation methods.