bluuebunny/crossref_metadata_2025_split huggingface dataset:
Square and rhombic lattices of magnetic skyrmions in a centrosymmetric binary compound
Authors: Takagi Rina , Matsuyama Naofumi , Ukleev Victor , Yu Le , White Jonathan S. , Francoual Sonia , Mardegan José R. L. , Hayami Satoru , Saito Hiraku , Kaneko Koji , Ohishi Kazuki , Ōnuki Yoshichika , Arima Taka-hisa , Tokura Yoshinori , Nakajima Taro , Seki Shinichiro 
Published: March 2022

AbstractMagnetic skyrmions are topologically stable swirling spin textures with particle-like character, and have been intensively studied as a candidate of high-density information bit. While magnetic skyrmions were originally discovered in noncentrosymmetric systems with Dzyaloshinskii-Moriya interaction, recently a nanometric skyrmion lattice has also been reported for centrosymmetric rare-earth compounds, such as Gd2PdSi3 and GdRu2Si2. For the latter systems, a distinct skyrmion formation mechanism mediated by itinerant electrons has been proposed, and the search of a simpler model system allowing for a better understanding of their intricate magnetic phase diagram is highly demanded. Here, we report the discovery of square and rhombic lattices of nanometric skyrmions in a centrosymmetric binary compound EuAl4, by performing small-angle neutron and resonant elastic X-ray scattering experiments. Unlike previously reported centrosymmetric skyrmion-hosting materials, EuAl4 shows multiple-step reorientation of the fundamental magnetic modulation vector as a function of magnetic field, probably reflecting a delicate balance of associated itinerant-electron-mediated interactions. The present results demonstrate that a variety of distinctive skyrmion orders can be derived even in a simple centrosymmetric binary compound, which highlights rare-earth intermetallic systems as a promising platform to realize/control the competition of multiple topological magnetic phases in a single material.
Cyclophilin anaCyp40 regulates photosystem assembly and phycobilisome association in a cyanobacterium
Authors: Yadav Shivam , Centola Martin , Glaesmann Mathilda , Pogoryelov Denys , Ladig Roman , Heilemann Mike , Rai L. C. , Yildiz Özkan , Schleiff Enrico 
Published: March 2022

AbstractCyclophilins, or immunophilins, are proteins found in many organisms including bacteria, plants and humans. Most of them display peptidyl-prolyl cis-trans isomerase activity, and play roles as chaperones or in signal transduction. Here, we show that cyclophilin anaCyp40 from the cyanobacterium Anabaena sp. PCC 7120 is enzymatically active, and seems to be involved in general stress responses and in assembly of photosynthetic complexes. The protein is associated with the thylakoid membrane and interacts with phycobilisome and photosystem components. Knockdown of anacyp40 leads to growth defects under high-salt and high-light conditions, and reduced energy transfer from phycobilisomes to photosystems. Elucidation of the anaCyp40 crystal structure at 1.2-Å resolution reveals an N-terminal helical domain with similarity to PsbQ components of plant photosystem II, and a C-terminal cyclophilin domain with a substrate-binding site. The anaCyp40 structure is distinct from that of other multi-domain cyclophilins (such as Arabidopsis thaliana Cyp38), and presents features that are absent in single-domain cyclophilins.
Tissue extracellular matrix hydrogels as alternatives to Matrigel for culturing gastrointestinal organoids
Authors: Kim Suran , Min Sungjin , Choi Yi Sun , Jo Sung-Hyun , Jung Jae Hun , Han Kyusun , Kim Jin , An Soohwan , Ji Yong Woo , Kim Yun-Gon , Cho Seung-Woo 
Published: March 2022

AbstractMatrigel, a mouse tumor extracellular matrix protein mixture, is an indispensable component of most organoid tissue culture. However, it has limited the utility of organoids for drug development and regenerative medicine due to its tumor-derived origin, batch-to-batch variation, high cost, and safety issues. Here, we demonstrate that gastrointestinal tissue-derived extracellular matrix hydrogels are suitable substitutes for Matrigel in gastrointestinal organoid culture. We found that the development and function of gastric or intestinal organoids grown in tissue extracellular matrix hydrogels are comparable or often superior to those in Matrigel. In addition, gastrointestinal extracellular matrix hydrogels enabled long-term subculture and transplantation of organoids by providing gastrointestinal tissue-mimetic microenvironments. Tissue-specific and age-related extracellular matrix profiles that affect organoid development were also elucidated through proteomic analysis. Together, our results suggest that extracellular matrix hydrogels derived from decellularized gastrointestinal tissues are effective alternatives to the current gold standard, Matrigel, and produce organoids suitable for gastrointestinal disease modeling, drug development, and tissue regeneration.
Structure of a tetrameric photosystem I from a glaucophyte alga Cyanophora paradoxa
Authors: Kato Koji , Nagao Ryo , Ueno Yoshifumi , Yokono Makio , Suzuki Takehiro , Jiang Tian-Yi , Dohmae Naoshi , Akita Fusamichi , Akimoto Seiji , Miyazaki Naoyuki , Shen Jian-Ren 
Published: March 2022

AbstractPhotosystem I (PSI) is one of the two photosystems functioning in light-energy harvesting, transfer, and electron transfer in photosynthesis. However, the oligomerization state of PSI is variable among photosynthetic organisms. We present a 3.8-Å resolution cryo-electron microscopic structure of tetrameric PSI isolated from the glaucophyte alga Cyanophora paradoxa, which reveals differences with PSI from other organisms in subunit composition and organization. The PSI tetramer is organized in a dimer of dimers with a C2 symmetry. Unlike cyanobacterial PSI tetramers, two of the four monomers are rotated around 90°, resulting in a completely different pattern of monomer-monomer interactions. Excitation-energy transfer among chlorophylls differs significantly between Cyanophora and cyanobacterial PSI tetramers. These structural and spectroscopic features reveal characteristic interactions and excitation-energy transfer in the Cyanophora PSI tetramer, suggesting that the Cyanophora PSI could represent a turning point in the evolution of PSI from prokaryotes to eukaryotes.
Donut-like organization of inhibition underlies categorical neural responses in the midbrain
Authors: Mahajan Nagaraj R. , Mysore Shreesh P. 
Published: March 2022

AbstractCategorical neural responses underlie various forms of selection and decision-making. Such binary-like responses promote robust signaling of the winner in the presence of input ambiguity and neural noise. Here, we show that a ‘donut-like’ inhibitory mechanism in which each competing option suppresses all options except itself, is highly effective at generating categorical neural responses. It surpasses motifs of feedback inhibition, recurrent excitation, and divisive normalization invoked frequently in decision-making models. We demonstrate experimentally not only that this mechanism operates in the midbrain spatial selection network in barn owls, but also that it is necessary for categorical signaling by it. The functional pattern of neural inhibition in the midbrain forms an exquisitely structured ‘multi-holed’ donut consistent with this network’s combinatorial inhibitory function for stimulus selection. Additionally, modeling reveals a generalizable neural implementation of the donut-like motif for categorical selection. Self-sparing inhibition may, therefore, be a powerful circuit module central to categorization.
Silver-catalyzed site-selective C(sp3)−H benzylation of ethers with N-triftosylhydrazones
Authors: Liu Zhaohong , Wang Hongwei , Sivaguru Paramasivam , Nolan Steven P. , Song Qingmin , Yu Weijie , Jiang Xinyu , Anderson Edward A. , Bi Xihe 
Published: March 2022

AbstractThe insertion of carbenes into the α-C–H bonds of ethers represents one of the most powerful approaches to access polysubstituted α-branched ethers. However, intermolecular carbene insertions remain challenging, since current approaches are generally limited to the use of toxic and potentially explosive α-diazocarbonyl compounds. We now report a silver-catalyzed α-C–H benzylation of ethers using bench-stable N-triftosylhydrazones as safe and convenient carbene precursors. This approach is well suited for both inter- and intramolecular insertions to deliver medicinally relevant homobenzylic ethers and 5–8-membered oxacycles in good yields. The synthetic utility of this strategy is demonstrated by its easy scalability, broad scope with valuable functional groups, high regioselectivity, and late-stage functionalization of complex oxygen-containing molecules. The relative reactivities of different types of silver carbenes and C−H bonds were also investigated by experments and DFT calculations.
Transcript and blood-microbiome analysis towards a blood diagnostic tool for goats affected by Haemonchus contortus
Authors: Tilahun Yonathan , Pinango Jessica Quijada , Johnson Felicia , Lett Charles , Smith Kayla , Gipson Terry , McCallum Malcolm , Hoyt Peter , Tritt Andrew , Yadav Archana , Elshahed Mostafa , Wang Zaisen 
Published: March 2022

AbstractThe Alpine goat (Capra aegagrus hircus) is parasitized by the barber pole worm (Haemonchus contortus). Hematological parameters from transcript and metagenome analysis in the host are reflective of infestation. We explored comparisons between blood samples of control, infected, infected zoledronic acid-treated, and infected antibody (anti-γδ T cells) treated wethers under controlled conditions. Seven days post-inoculation (dpi), we identified 7,627 transcripts associated with the different treatment types. Microbiome measurements at 7 dpi revealed fewer raw read counts across all treatments and a less diverse microbial flora than at 21 dpi. This study identifies treatment specific transcripts and an increase in microflora abundance and diversity as wethers age. Further, F/B ratio reflect health, based on depression or elevation above thresholds defined by the baseline of non-infected controls. Forty Alpine wethers were studied where blood samples were collected from five goats in four treatment groups on 7 dpi and 21 dpi. Transcript and microbiome profiles were obtained using the Partek Flow (St. Louis, Missouri, USA) software suites pipelines. Inflammation comparisons were based on the Firmicutes/Bacteriodetes ratios that are calculated as well as the reduction of microbial diversity.
Influences of freezing–thawing actions on mechanical properties of soils and stress and deformation of soil slope in cold regions
Authors: Xiang Bo , Liu Enlong , Yang Liuxin 
Published: March 2022

AbstractFreezing–thawing actions can affect the mechanical features of soil greatly, which is vital for the stability of soil slope in cold regions. Firstly, triaxial compression tests on sand samples under undrained conditions were performed to investigate the influences of freezing–thawing cycles, which shows that the freezing–thawing actions can weaken their strength and stiffness, and with the increasing freezing–thawing cycles, both the deviatoric stress and pore water pressure decrease gradually. Then, the double hardening constitutive model was revised to model the influences of freezing–thawing cycles in consideration of the influences of freezing–thawing actions, and the model was also validated by the test results. Finally, the proposed constitutive model was incorporated into a finite element code to numerically simulate the distribution of displacement and pore water pressure of sand slope subjected to freezing–thawing cycles, which shows that the freezing–thawing actions accelerate the dissipation of the pore water pressure and enlarge the displacement of the slope. The study here can provide a help in designing and construction of civil engineering in cold regions.
Aging and the perception of tactile speed
Authors: Norman J. Farley , Eaton Jerica R. , Gunter McKenzie L. , Baig Maheen 
Published: March 2022

AbstractEighteen younger and older adults (mean ages were 20.4 and 72.8 years, respectively) participated in a tactile speed matching task. On any given trial, the participants felt the surfaces of rotating standard and test wheels with their index fingertip and were required to adjust the test wheel until its speed appeared to match that of the standard wheel. Three different standard speeds were utilized (30, 50, and 70 cm/s). The results indicated that while the accuracy of the participants’ judgments was similar for younger and older adults, the precision (i.e., reliability across repeated trials) of the older participants’ judgments deteriorated significantly relative to that exhibited by the younger adults. While adverse effects of age were obtained with regards to both the precision of tactile speed judgments and the participants’ tactile acuity, there was nevertheless no significant correlation between the older adults’ tactile acuities and the precision of their tactile speed judgments.
Hard ferromagnetic behavior in atomically thin CrSiTe3 flakes
Authors: Zhang Cheng , Wang Le , Gu Yue , Zhang Xi , Xia Xiuquan , Jiang Shaolong , Huang Liang-Long , Fu Ying , Liu Cai , Lin Junhao , Zou Xiaolong , Su Huimin , Mei Jia-Wei , Dai Jun-Feng 
Published: March 2022

We reported a layer-controlled transition from the soft to hard ferromagnetic state in atomically thin CrSiTe3 flakes. Our study paves the way towards exploring and learning much more atomically thin and layered intrinsic ferromagnets.
Contributions of Forward-Focused Voice to Audio-Vocal Feedback Measured Using Nasal Accelerometry and Power Spectral Analysis of Vocal Fundamental Frequency
Authors: Lee Shao-Hsuan , Torng Pao-Chuan , Lee Guo-She 
Published: March 2022

Purpose:The spectral powers of the modulations of vocal fundamental frequency (fo) less than 3 Hz (low-frequency power, LFP) and between 3 and 8 Hz (middle-frequency power, MFP) had been established to indicate the audio-vocal feedback status and vocal efficiency of a speaker, and a resonant voice may enhance the auditory-vocal feedback. This study aims to determine whether the auditory feedback can be augmented by a forward and resonant voice and therefore contribute to the modulations offovariability.Method:Vocal signals and accelerometric signals of lateral nasal cartilage were obtained from 27 healthy adults who, respectively, sustained vowels /a/ and /i/ with their habitual speaking voice and with a forward-focused voice under three auditory conditions: natural hearing (N0), high-level noise exposure (N90), and low-level noise exposure (N60). Nasal skin vibrations were measured using a nasal accelerometry to reflect voice resonance status. Vocal intensity andfovariability were also analyzed to show the auditory-vocal interactions under varied conditions of auditory feedback and voice resonance.Results:In both N0 and N90 conditions, forward-focused voice showed a significantly lower LFP than the speakers' habitual voice. In addition, LFP offowould significantly increase during natural voice production as the voice feedback was greatly masked by high-intensity noise; however, with a forward-focused voice, the noise-induced variation in LFP was significantly decreased. Under N90, MFP significantly decreased during forward-focused voice production compared with that measured during natural voice production. The stability offomodulations was not adversely affected by N60.Conclusion:The results support the idea that vocalizing with a forward-focused voice enhance the auditory feedback of the speaker's own voice and, thus, reduce the variability offoduring sustained phonation, especially when vocalizing in the high noise condition.
The analysis of steady‐state operation characteristic and resonance phenomenon considering all the harmonic components of modular multilevel converter for HVDC
Authors: Liu Pu , Liu Di , Shen Yongpeng , Yang Xiaoliang , Zhao Jun , Wang Yanfeng 
Published: March 2022

AbstractAnalysing the steady‐state operation characteristic of the modular multilevel converter (MMC) in time domain poses challenges due to the presence of harmonic components in the arm current and capacitor voltage. While ignoring the influence of the harmonic currents and harmonic voltages would reduce the accuracy of the analysis results for MMC. This paper investigates the circular interaction among the electrical quantities and different order harmonic components in MMC. A new steady‐state model is developed and the general matrix equation is established to accurately describe the explicit analytical expressions for electrical variables in MMC without specific assumptions. Based on the steady‐state operation characteristic analysis, the resonance phenomenon and characteristic are identified for MMC. Finally, the feasibility and accuracy of the proposed method are verified by comparing its analytical results with simulation and experimental results.
1,1-Difunctionalization of α‑Carbonyl Sulfur Ylides with Thiosulfonates: Synthesis of β-Keto Thiosulfones
Authors: Zeng Qingle , Kang Xiaokang , Lai Shuyan , Liang Xiayu 
Published: March 2022

Abstract1,1-Difunctionalization of α‑carbonyl sulfur ylides and thiosulfonates under simple conditions is disclosed. In this protocol, two new C–S bonds are constructed in a one-step reaction. A series of aliphatic and aromatic β-keto thiosulfones were obtained in moderate to good yields. This reaction probably proceeds through sulfur ylide-involved­ nucleophilic substitution of an ion pair within a solvent cage.
Clarifying the Link Between the Blood Lactate Concentration and
Cardiovascular Risk
Authors: Ahlgrim Christoph , Baumstark Manfred W. , Roecker Kai 
Published: March 2022

AbstractThe blood lactate value at rest (Lacrest) is linked to cardiovascular
outcomes. It is unclear whether this association holds true in younger, healthy
subjects, especially as the pathophysiological connection between
Lacrest and cardiometabolic disease is not well understood. The
aim of this study is clarifying the link between Lacrest and
cardiovascular risk, and to study explanatory factors for the variance of
Lacrest concerning metabolism and physical activity in a
population of healthy patient-athletes. The distribution and intra-individual
variability of Lacrest was assessed based on 9051 samples. The
10-year cardiovascular risk was then approximated using the Framingham risk
score in a group of 1315 samples from patient-athletes. Cross-validated linear
regression was used to analyze explanatory variables for Lacrest and
10-year cardiovascular risk. Lacrest is weakly associated with the
Framingham score. This association disappears when adjusting for blood lipids.
Lacrest is also linked to the predominant type of exercise with
endurance athletes featuring a higher Lacrest. Lacrest
does not independently predict the estimated cardiovascular risk but is
associated with lipid parameters. Moreover, the intra-individual variability of
Lacrest is high in a relevant number of subjects, which does not
point towards the feasibility to use Lacrest as an individual risk
factor.
Synthesis of Phosphoramidate Prodrugs of Phenolic Natural Products and Drugs by Ester Exchange
Authors: Wu Fan , Ni Feng , Yao Jie , Huang Chengjie , Zhao Yufen 
Published: March 2022

AbstractDrug development based on phenolic natural products as drug candidates against various diseases has gained much attention in recent years. However, most of those molecules lack therapeutic efficacy in clinical trials, usually due to poor bioavailability. Therefore, a prodrug approach was adopted to address the bioavailability problem of phenolic drugs. This paper describes a mild and convenient method for late-stage ProTide-type prodrug synthesis of phenolic pharmaceuticals, which gives various phosphoramidate prodrugs from unprotected phenolic natural products and drugs in high yield. More importantly, this reaction is amenable for the selective phosphorylation of the phenolic hydroxyl group in the presence of otherwise problematic nucleophilic functional groups like amines and alcohols. We also observed that the chemical release rate of the phenol can be substantially tuned by changing the amino acid residue on the phosphoramidate moiety.
Design of the ion-optics for the MRSt neutron spectrometer at the National Ignition Facility (NIF)
Authors: Berg G. P. A. , Frenje J. A. , Kunimune J. H. , Trosseille C. A. , Couder M. , Kilkenny J. D. , Mackinnon A. J. , Moore A. S. , Waltz C. S. , Wiescher M. C. 
Published: March 2022

A new Magnetic Recoil Spectrometer (MRSt) is designed to provide time-resolved measurements of the energy spectrum of neutrons emanating from an inertial confinement fusion implosion at the National Ignition Facility. At present, time integrated parameters are being measured using the existing magnet recoil and neutron time-of-flight spectrometers. The capability of high energy resolution of 2 keV and the extension to high time resolution of about 20 ps are expected to improve our understanding of conditions required for successful fusion experiments. The layout, ion-optics, and specifications of the MRSt will be presented.
Ultra-broadband mid-infrared frequency combs produced by optical subharmonic generation
Authors: Vodopyanov K.L. 
Published: March 2022

Abstract
Optical frequency combs have revolutionised accurate frequency and time measurements and have enabled broadband and simultaneously high resolution spectroscopic measurements that were not previously possible. This paper is an overview of the main results of the previously performed work, describing a new approach to extending frequency combs to the mid-infrared ‘molecular signature’ range using a subharmonic generator based on an optical parametric oscillator operating in degenerate mode. Such an instrument acts as an efficient frequency divider that rigorously down-converts and augments the spectrum of a pump laser frequency comb while maintaining its coherence. Our recent result is the demonstration of a subharmonic system with a two-octave spectrum, 3 – 12 μm, which covers vibrational resonances for most molecular species. Potentially, through frequency division in the coherent subharmonic optical parametric amplifier regime, this method can be used to obtain intense long-wavelength pulses for high-field physics applications.
Semiconductor disk laser with a wavelength of 780 nm based on a MOCVD-grown Al
x
Ga1–x
As/Al
y
Ga1–y
As heterostructure with optical and electron beam pumping
Authors: Butaev M.R. , Skasyrsky Ya.K. , Kozlovsky V.I. , Andreev A.Yu. , Yarotskaya I.V. , Marmalyuk A.A. 
Published: March 2022

Abstract
A pulsed semiconductor disk laser based on the Al
x
Ga1 – x
As/Al
y
Ga1 – y
As structure with resonantly periodic gain and a built-in Bragg mirror emitting at a wavelength near 780 nm is studied. The laser characteristics are presented both for pumping by an electron beam and for optical pumping by laser diode radiation with a wavelength of 450 nm. Under pumping by an electron beam, a peak power of 4.4 W is achieved with a slope efficiency of over 10 %, while under optical pumping, the power is 0.2 W with a slope efficiency of 2.2 % and approximately the same cavity parameters. Possible reasons for the lower powers and efficiency under optical pumping are discussed.
Comparison of field shifts in an atomic clock based on the effect of coherent population trapping in 87Rb atoms under modulation of laser pump current at frequencies of 3.4 and 6.8 GHz
Authors: Ignatovich S.M. , Skvortsov M.N. , Mesenzova I.S. , Kvashnin L.N. , Vishnyakov V.I. , Brazhnikov D.V. , Bagayev S.N. 
Published: March 2022

Abstract
Experimental parameters of the resonance of coherent population trapping (CTP) on D1 line in 87Rb and light shifts are compared under modulation of the laser pump current at frequencies of 3.4 and 6.8 GHz. Reproducibility of the parameters of a laser with a vertical cavity needed for long-term stability of an atomic clock is considered. The instabilities of atomic CPT-clock obtained for 1 s are 1.2 × 10−11 and 3 × 10−12 for frequencies of 3.4 GHz and 6.8 GHz, respectively.