bluuebunny/crossref_metadata_2025 huggingface dataset:
On the classification of

-dimensional spherical Sasakian manifolds
Authors: Sykes D. , Schmalz G. , Ezhov V. V.
Published: November 2020

In this article we regard spherical hypersurfaces in

with a fixed Reeb vector field as

-dimensional Sasakian manifolds. We establish a correspondence between three different sets of parameters, namely, those arising from representing the Reeb vector field as an automorphism of the Heisenberg sphere, those used in Stanton’s description of rigid spheres, and those arising from the rigid normal forms. We also describe geometrically the moduli space for rigid spheres and provide a geometric distinction between Stanton hypersurfaces and those found in [1]. Finally, we determine the Sasakian automorphism groups of rigid spheres and detect the homogeneous Sasakian manifolds among them.
Explicit minimizers of some non-local anisotropic energies: a short proof
Authors: Mateu J. , Mora M. G. , Rondi L. , Scardia L. , Verdera J.
Published: November 2020

In this paper we consider non-local energies defined on probability measures in the plane, given by a convolution interaction term plus a quadratic confinement. The interaction kernel is

,

, with

. This kernel is anisotropic except for the Coulomb case

. We present a short compact proof of the known surprising fact that the unique minimizer of the energy is the normalized characteristic function of the domain enclosed by an ellipse with horizontal semi-axis

and vertical semi-axis

. Letting

, we find that the semicircle law on the vertical axis is the unique minimizer of the corresponding energy, a result related to interacting dislocations, and previously obtained by some of the authors. We devote the first sections of this paper to presenting some well-known background material in the simplest way possible, so that readers unfamiliar with the subject find the proofs accessible.
On compact subsets possessing strictly plurisubharmonic functions
Authors: Shcherbina N. V.
Published: November 2020

We give a geometric condition on a compact subset of a complex manifold which is necessary and sufficient for the existence of a smooth strictly plurisubharmonic function defined in a neighbourhood of this set.
Symmetries of a two-dimensional continued fraction
Authors: German O. N. , Tlyustangelov I. A.
Published: November 2020

We describe the symmetry group of a multidimensional continued fraction. As a multidimensional generalization of continued fractions we consider Klein polyhedra. We distinguish two types of symmetries: Dirichlet symmetries, which correspond to the multiplication by units of the respective extension of

, and so-called palindromic symmetries. The main result is a criterion for a two-dimensional continued fraction to have palindromic symmetries, which is analogous to the well-known criterion for the continued fraction of a quadratic irrationality to have a symmetric period.
Plane algebraic curves in fancy balls
Authors: Kruzhilin N. G. , Orevkov S. Yu.
Published: November 2020

Boileau and Rudolph [1] called an oriented link

in the 3-sphere a

-boundary if it can be realized as the intersection of an algebraic curve

in

and the boundary of a smooth embedded closed 4-ball

. They showed that some links are not

-boundaries. We say that

is a strong

-boundary if

is connected. In particular, all quasipositive links are strong

-boundaries.

In this paper we give examples of non-quasipositive strong

-boundaries and non-strong

-boundaries. We give a complete classification of (strong)

-boundaries with at most five crossings.
The Diophantine problem in the classical matrix groups
Authors: Myasnikov A. G. , Sohrabi M.
Published: November 2020

In this paper we study the Diophantine problem in the classical matrix groups

,

,

and

,

, over an associative ring

with identity. We show that if

is one of these groups, then the Diophantine problem in

is polynomial-time equivalent (more precisely, Karp equivalent) to the Diophantine problem in

. When

we assume that

is commutative. Similar results hold for

and

provided

has no zero divisors (for

the ring

is not assumed to be commutative).
On a spectral sequence for the action of the Torelli group of genus

on the complex of cycles
Authors: Gaifullin A. A.
Published: November 2020

The Torelli group of a closed oriented surface

of genus

is the subgroup

of the mapping class group

consisting of all mapping classes that act trivially on the homology of

. One of the most intriguing open problems concerning Torelli groups is the question of whether the group

is finitely presented. A possible approach to this problem relies on the study of the second homology group of

using the spectral sequence

for the action of

on the complex of cycles. In this paper we obtain evidence for the conjecture that

is not finitely generated and hence

is not finitely presented. Namely, we prove that the term

of the spectral sequence is not finitely generated, that is, the group

remains infinitely generated after taking quotients by the images of the differentials

and

. Proving that it remains infinitely generated after taking the quotient by the image of

would complete the proof that

is not finitely presented.
The Fermat-Steiner problem in the space of compact subsets of

endowed with the Hausdorff metric
Authors: Galstyan A. Kh. , Ivanov A. O. , Tuzhilin A. A.
Published: November 2020

The Fermat-Steiner problem consists in finding all points in a metric space

at which the sum of the distances to fixed points

of

attains its minimum value. This problem is studied in the metric space

of all nonempty compact subsets of the Euclidean space

, and the

are pairwise disjoint finite sets in

. The set of solutions of this problem (which are called Steiner compact sets) falls into different classes in accordance with the distances to the

. Each class contains an inclusion-greatest element and inclusion-minimal elements (a maximal Steiner compact set and minimal Steiner compact sets, respectively). We find a necessary and sufficient condition for a compact set to be a minimal Steiner compact set in a given class, provide an algorithm for constructing such compact sets and find a sharp estimate for their cardinalities. We also put forward a number of geometric properties of minimal and maximal compact sets. The results obtained can significantly facilitate the solution of specific problems, which is demonstrated by the well-known example of a symmetric set

, for which all Steiner compact sets are asymmetric. The analysis of this case is significantly simplified due to the technique developed.

Bibliography 16 titles.
Distance metrics for ranked evolutionary trees
Authors: Kim Jaehee , Rosenberg Noah A. , Palacios Julia A.
Published: November 2020

Significance

Rooted binary trees inferred from molecular sequence data provide information about the evolutionary history of populations and species. We introduce metrics on ranked tree shapes and ranked genealogies, in which the shape and temporal branching order in a tree are considered, but not the taxon labels. Our metrics enable quantification of evolutionary differences, assessment of tree uncertainty, and construction of statistical summaries of a tree distribution. They are computationally efficient and particularly useful for comparing phylodynamics of infectious diseases involving heterochronous samples and for comparative analyses of organisms that live in different geographic regions.
Forest and woodland replacement patterns following drought-related mortality
Authors: Batllori Enric , Lloret Francisco , Aakala Tuomas , Anderegg William R. L. , Aynekulu Ermias , Bendixsen Devin P. , Bentouati Abdallah , Bigler Christof , Burk C. John , Camarero J. Julio , Colangelo Michele , Coop Jonathan D. , Fensham Roderick , Floyd M. Lisa , Galiano Lucía , Ganey Joseph L. , Gonzalez Patrick , Jacobsen Anna L. , Kane Jeffrey Michael , Kitzberger Thomas , Linares Juan C. , Marchetti Suzanne B. , Matusick George , Michaelian Michael , Navarro-Cerrillo Rafael M. , Pratt Robert Brandon , Redmond Miranda D. , Rigling Andreas , Ripullone Francesco , Sangüesa-Barreda Gabriel , Sasal Yamila , Saura-Mas Sandra , Suarez Maria Laura , Veblen Thomas T. , Vilà-Cabrera Albert , Vincke Caroline , Zeeman Ben
Published: November 2020

Significance

Forests are experiencing growing risks of drought-induced mortality in a warming world. Yet, ecosystem dynamics following drought mortality remain unknown, representing a major limitation to our understanding of the ecological consequences of climate change. We provide an emerging picture of postdrought ecological trajectories based on field indicators of forest dynamics. Replacement patterns following mortality indicate limited short-term persistence of predrought dominant tree species, highlighting the potential for major ecosystem reorganization in the coming decades. The great variability of the observed dynamics within and among species reinforces the primary influence of drought characteristics and ecosystem legacies, modulated by land use, management, and past disturbances, on ongoing drought-related species turnover and their potential implications for future forest biodiversity and ecosystem services.
Early evidence for mounted horseback riding in northwest China
Authors: Li Yue , Zhang Chengrui , Taylor William Timothy Treal , Chen Liang , Flad Rowan K. , Boivin Nicole , Liu Huan , You Yue , Wang Jianxin , Ren Meng , Xi Tongyuan , Han Yifu , Wen Rui , Ma Jian
Published: November 2020

Significance

This study provides insights into the emergence and adoption of equestrian technologies in China. Analysis of ancient horse bones from Shirenzigou and Xigou in eastern Xinjiang demonstrates that pastoralists along China’s northwest frontier practiced horseback riding and mounted archery by the fourth century BCE. This region may have played a key role in the initial spread of equestrian technologies from the Altai region into the heartland of China’s early settled states, where they eventually facilitated the rise of the first united empires in China and triggered extensive social, political, and economic exchanges between China and its neighbors on the Eurasian Steppes.
Comparative roles of charge,
π
, and hydrophobic interactions in sequence-dependent phase separation of intrinsically disordered proteins
Authors: Das Suman , Lin Yi-Hsuan , Vernon Robert M. , Forman-Kay Julie D. , Chan Hue Sun
Published: November 2020

Significance

Mesoscopic condensates of proteins and nucleic acids, including membraneless organelles, serve myriad biological functions, whereas dysregulation of condensates can cause disease. How condensates are governed by genetically encoded biomolecular sequences is of central importance. Critical assessment of how various interactions reproduce experimental phase behaviors indicates that

π

-interactions’ notable facilitation of condensate formation is well reflected in established contact statistics among folded protein structures, although the condensate-driving capability of the large hydrophobic/aromatic residue phenylalanine is weaker than expected. By elucidating physical aspects of the residue–residue contacts in condensates, highlighting these contacts’ largely solvent-exposed character with ramifications such as reduced hydrophobic strengths relative to buried nonpolar contacts, fundamental conceptual and quantitative progress is made toward predictive models for biomolecular condensates.
Mechanical injuries of neurons induce tau mislocalization to dendritic spines and tau-dependent synaptic dysfunction
Authors: Braun Nicholas J. , Yao Katherine R. , Alford Patrick W. , Liao Dezhi
Published: November 2020

Significance

Athletes and soldiers exposed to repeated traumatic brain injuries have increased risk of developing chronic traumatic encephalopathy (CTE), which is a neurodegenerative disease characterized by tangled deposits of the protein tau in the brain and loss of cognitive function. This study provides the first experimental evidence showing that mechanical stretching of neurons induces tau to be mislocalized to dendritic spines where it causes synaptic dysfunction. This cross-disciplinary study utilizes computational modeling, imaging, and electrophysiology to unravel a cellular framework for how tau phosphorylation mediates trauma-induced synaptic dysfunction, highlighting the essential role of tau in functional deficits caused by traumatic brain injury.
β-Catenin signaling dynamics regulate cell fate in differentiating neural stem cells
Authors: Rosenbloom Alyssa B. , Tarczyński Marcin , Lam Nora , Kane Ravi S. , Bugaj Lukasz J. , Schaffer David V.
Published: November 2020

Significance

Stem cells in the adult brain undergo a weeks-long differentiation process to become new neurons. During this process, the stem cell continuously senses differentiation cues, which fluctuate over a wide range of physiological timescales. However, how differentiation can proceed reliably despite these fluctuations is poorly understood. We use light-activatable control of the neurogenic β-catenin signal to probe how adult neurogenesis responds to fluctuations in differentiation cues. We discovered that β-catenin dynamics strongly influence cell-fate decisions. Surprisingly, while a sustained signal resulted in neurogenesis, transient signals induced cell death. Our results may provide an explanation for the cell death that is commonly observed during adult neurogenesis and may also illuminate a quality control mechanism for correcting errors during neurogenesis.
Evidence for aggregation-independent, PrP
C
-mediated Aβ cellular internalization
Authors: Foley Alejandro R. , Roseman Graham P. , Chan Ka , Smart Amanda , Finn Thomas S. , Yang Kevin , Lokey R. Scott , Millhauser Glenn L. , Raskatov Jevgenij A.
Published: November 2020

Significance

Amyloid β (Aβ) aggregation has been the therapeutic target of several Alzheimer’s disease (AD) clinical trials. Aβ exists in many different aggregated forms, making it exceedingly challenging to target. Evidence links intracellular Aβ accumulation and AD pathogenesis. We report that amino acids 1 to 30 of Aβ, Aβ (1–30), do not aggregate yet display cellular uptake stereospecificity when compared to its mirror image, suggesting that Aβ uptake is predominantly receptor-mediated and may be independent from its aggregation state. Additionally, we found Aβ (1–30) internalization to depend on PrP
C
expression. Aβ (1–30) thus represents a powerful tool to study mechanisms of Aβ cellular internalization and suggests that Aβ uptake could be modulated by therapeutically targeting high-affinity Aβ receptors.
Vibrio cholerae
adapts to sessile and motile lifestyles by cyclic di-GMP regulation of cell shape
Authors: Fernandez Nicolas L. , Hsueh Brian Y. , Nhu Nguyen T. Q. , Franklin Joshua L. , Dufour Yann S. , Waters Christopher M.
Published: November 2020

Significance

Form follows function is true of living organisms, including bacteria, as the shapes and morphology they adopt contribute to their biological characteristics. But whether bacteria can actively change their shape to adapt to their environment is less understood.
Vibrio cholerae
, the pathogenic bacterium responsible for the diarrheal disease cholera, adopts a characteristic “comma”-shaped cell morphology. Here we show that the intracellular signaling molecule, cyclic di-GMP, drives curved
V. cholerae
to adopt a straight cell morphology that is advantageous to a sessile biofilm lifestyle, while curved
V. cholerae
are better adapted for swimming. Our research provides a clear example of how bacteria can actively alter their form to impact function.
Role of inner solvation sheath within salt–solvent complexes in tailoring electrode/electrolyte interphases for lithium metal batteries
Authors: Ren Xiaodi , Gao Peiyuan , Zou Lianfeng , Jiao Shuhong , Cao Xia , Zhang Xianhui , Jia Hao , Engelhard Mark H. , Matthews Bethany E. , Wu Haiping , Lee Hongkyung , Niu Chaojiang , Wang Chongmin , Arey Bruce W. , Xiao Jie , Liu Jun , Zhang Ji-Guang , Xu Wu
Published: November 2020

Significance

Rechargeable lithium metal batteries are promising next-generation high-energy-density energy storage systems. However, their applications have been greatly impeded by the instabilities of electrolytes toward both highly reductive lithium metal anode and high-voltage cathodes. Here, we use localized high-concentration electrolytes to investigate the fundamental correlation between the battery performance and the electrolyte solvation chemistry and its profound electrode/electrolyte interphase properties. Experimental and theoretical analyses reveal an intriguing general rule that the strong interactions between the salt and the solvent in the inner solvation sheath within the salt–solvent complexes promote their intermolecular proton/charge-transfer reactions, dictate the properties of the electrode/electrolyte interphases, and then influence the battery performances. These findings can shed light for rational electrolyte design for various battery systems.
Hedgehog pathway activation through nanobody-mediated conformational blockade of the Patched sterol conduit
Authors: Zhang Yunxiao , Lu Wan-Jin , Bulkley David P. , Liang Jiahao , Ralko Arthur , Han Shuo , Roberts Kelsey J. , Li Anping , Cho Wonhwa , Cheng Yifan , Manglik Aashish , Beachy Philip A.
Published: November 2020

Significance

Precise manipulation of Hedgehog pathway activity holds great value for biological research and clinical applications, but pathway agonists amenable to engineering have been lacking. We selected a nanobody that potentially targets the conformational changes of the Hedgehog receptor Patched1 and demonstrated that this nanobody potently activates the pathway in vivo. This nanobody can serve as the basis for mechanistic studies of Hedgehog pathway activation and for potential therapeutic applications. Our method may further apply to the investigation of other related transporters in the Resistance-Nodulation-Division superfamily.
Echolocating bats accumulate information from acoustic snapshots to predict auditory object motion
Authors: Salles Angeles , Diebold Clarice Anna , Moss Cynthia F.
Published: November 2020

Significance

Research on visual tracking of moving stimuli has contributed to our understanding of sensory-guided behaviors; however, the processes that support auditory object tracking in natural three-dimensional environments remain largely unknown. This is important, not only to diverse groups of animals, but also to humans that rely on hearing to track objects in their environment. For visually impaired individuals, hearing is paramount for auditory object tracking and navigation, and in recent years, mobility training programs for the blind include instruction on echolocation using tongue clicks. In this work, we provide conclusive demonstration that echolocating bats use predictive strategies to track moving auditory objects, which can inform future comparative work on auditory motion processing.
Antibody-mediated activation of the FGFR1/Klothoβ complex corrects metabolic dysfunction and alters food preference in obese humans
Authors: Baruch Amos , Wong Chin , Chinn Leslie W. , Vaze Anjali , Sonoda Junichiro , Gelzleichter Thomas , Chen Shan , Lewin-Koh Nicholas , Morrow Linda , Dheerendra Suresh , Boismenu Richard , Gutierrez Johnny , Wakshull Eric , Wilson Maria E. , Arora Puneet S.
Published: November 2020

Significance

Fibroblast growth factor 21 (FGF21) controls metabolic organ homeostasis and eating behavior via FGF receptor 1/Klothoβ (FGFR1/KLB) complexes. Here we show that a bispecific anti-FGFR1/KLB agonist antibody, BFKB8488A, mimics the actions of FGF21 in monkeys and humans. BFKB8488A induced marked weight loss in obese monkeys while elevating expression of FGFR1 target genes in adipose tissue. A clinical study in overweight human participants demonstrated that a single dose of BFKB8488A caused transient body weight reduction, sustained improvement in cardiometabolic parameters, and a trend toward reduction in preference for sweet taste and carbohydrate intake. These data suggest that antibody-mediated activation of the FGFR1/KLB complex in humans recapitulates the effects of FGF21 and can be used as therapy for obesity-related metabolic defects.
Mechanically superior matrices promote osteointegration and regeneration of anterior cruciate ligament tissue in rabbits
Authors: Mengsteab Paulos Y. , Otsuka Takayoshi , McClinton Aneesah , Shemshaki Nikoo Saveh , Shah Shiv , Kan Ho-Man , Obopilwe Elifho , Vella Anthony T. , Nair Lakshmi S. , Laurencin Cato T.
Published: November 2020

Significance

This paper describes a mechanically superior matrix that enhances the osteointegration and regeneration of ACL tissue in a rabbit model. We show that bone marrow aspirate concentrate enhances the presence of cuboidal cells that are reminiscent of ACL fibroblasts and chondrocytes, a sign of enhanced regeneration. This paper also demonstrates that the combinatorial application of FGF-2 and FGF-8 in the knee joint suppresses inflammation by reducing adipokine secretion. The incorporation of nondegradable PET fibers into the PLLA bioengineered ACL matrix showed improved strength retention after implantation. We report the strongest matrix to date in a rabbit ACL reconstruction model, which is a promising step toward the clinical translation of an off-the-shelf ligament for orthopedic applications.
COVID-19 pandemic impacts on global inland fisheries
Authors: Stokes Gretchen L. , Lynch Abigail J. , Lowe Benjamin S. , Funge-Smith Simon , Valbo‐Jørgensen John , Smidt Samuel J.
Published: November 2020

The COVID-19 pandemic has led to environmental recovery in some ecosystems from a global “anthropause,” yet such evidence for natural resources with extraction or production value (e.g., fisheries) is limited. This brief report provides a data-driven global snapshot of expert-perceived impacts of COVID-19 on inland fisheries. We distributed an online survey assessing perceptions of inland fishery pressures in June and July 2020 to basin-level inland fishery experts (i.e., identified by the Food and Agriculture Organization of the United Nations across the global North and South); 437 respondents from 79 countries addressed 93 unique hydrological basins, accounting for 82.1% of global inland fish catch. Based on the responses analyzed against extrinsic fish catch and human development index data, pandemic impacts on inland fisheries 1) add gradation to the largely positive environmental narrative of the global pandemic and 2) identify that basins of higher provisioning value are perceived to experience greater fishery pressures but may have limited compensatory capacity to mitigate COVID-19 impacts along with negative pressures already present.
Essential role of the linear ubiquitin chain assembly complex and TAK1 kinase in A20 mutant Hodgkin lymphoma
Authors: Song Zhihui , Wei Wei , Xiao Wenming , Al-Saleem Essel D. , Nejati Reza , Chen Liqi , Yin Jiejing , Fabrizio Joseph , Petrus Michael N. , Waldmann Thomas A. , Yang Yibin
Published: November 2020

Significance

Hodgkin lymphoma (HL) is the most common (6,000 to 7,000 new cases per year) lymphoma subtype in young adulthood. Our study is the first effort to investigate the deep mechanisms underlying the recurrent A20 mutations in HL based on results from a high-throughput ubiquitin regulator-focused CRISPR library screen. Our results reveal the essential role of the linear-ubiquitination E3 ligase LUBAC and protein kinase TAK1 in the oncogenic NF-κB signaling that characterizes HL, leading to improved understanding of the molecular circuitry that drives the pathology of HL. The therapeutic potential of targeting this pathway was tested using a highly specific TAK1 small-molecule inhibitor, which is an approach that can provide intervention strategies for targeted therapy in this disease.
In situ sprayed NIR-responsive, analgesic black phosphorus-based gel for diabetic ulcer treatment
Authors: Ouyang Jiang , Ji Xiaoyuan , Zhang Xingcai , Feng Chan , Tang Zhongmin , Kong Na , Xie Angel , Wang Junqing , Sui Xinbing , Deng Liu , Liu Younian , Kim Jong Seung , Cao Yihai , Tao Wei
Published: November 2020

Significance

How to achieve effective treatment of diabetic ulcer (DU) is still a major challenge in the clinic. Herein, we propose an effective strategy to perfectly address all the problems faced in the treatment of DU. A near-infrared–responsive black phosphorus-based sprayed fibrin gel capable of alleviating pain, eliminating bacteria, reducing inflammation, and promoting angiogenesis is developed. The promoting wound healing and pain relief effects in the diabetic mouse ulcer model indicate this gel is a valuable wound dressing for effective treatment of DU and other advanced wounds. We anticipate that this therapeutic strategy may be generalized for treating other disorders such as chronic inflammation and infections.
Chlorovirus PBCV-1 protein A064R has three of the transferase activities necessary to synthesize its capsid protein N-linked glycans
Authors: Speciale Immacolata , Laugieri Maria Elena , Noel Eric , Lin Sicheng , Lowary Todd L. , Molinaro Antonio , Duncan Garry A. , Agarkova Irina V. , Garozzo Domenico , Tonetti Michela G. , Van Etten James L. , De Castro Cristina
Published: November 2020

Significance

The chloroviruses are unusual because they are predicted to encode most, if not all, of the machinery to synthesize the glycans attached to their major capsid proteins. Here we show that two of the virus-encoded proteins A064R and A061L are functionally active. A064R has three domains: The first two are GTs and the third domain is a methyltransferase. A061L has a methyltransferase activity. The action of these two enzymes produce the fragment 2,3-di-O-methyl-α-
l
-Rha-(1→2)-β-
l
-Rha, which is part of the complex N-linked glycan attached to the virus capsid protein. A064R domain 2 is a member of a new GT family. This provides direct evidence that the synthesis of PBCV-1 glycans are accomplished with virus-encoded enzymes.
Optogenetic regulation of embryo implantation in mice using photoactivatable CRISPR-Cas9
Authors: Takao Tomoka , Sato Moritoshi , Maruyama Tetsuo
Published: November 2020

Embryo implantation is achieved upon successful interaction between a fertilized egg and receptive endometrium and is mediated by spatiotemporal expression of implantation-associated molecules including leukemia inhibitory factor (LIF). Here we demonstrate, in mice, that LIF knockdown via a photoactivatable CRISPR-Cas9 gene editing system and illumination with a light-emitting diode can spatiotemporally disrupt fertility. This system enables dissection of spatiotemporal molecular mechanisms associated with embryo implantation and provides a therapeutic strategy for temporal control of reproductive functions in vivo.
Greigite (Fe
3
S
4
) is thermodynamically stable: Implications for its terrestrial and planetary occurrence
Authors: Subramani Tamilarasan , Lilova Kristina , Abramchuk Mykola , Leinenweber Kurt D. , Navrotsky Alexandra
Published: November 2020

Significance

The new experimental thermodynamic studies of bulk, nanophase, and monoclinic high-pressure forms of greigite (Fe
3
S
4
) confirm its stability in the Fe–S system and explain its common occurrence in sediments, magnetotactic bacteria, and other ambient temperature environments under anoxic conditions. The data disprove the commonly held hypothesis that greigite is a metastable phase. The low surface energy of greigite provides insight not only into the stability of greigite nanoparticles but also into their role in prebiotic, biological, and planetary processes. Our experimental data for the stability of the three forms of Fe
3
S
4
confirm that it could be stable on Mercury, thus contributing to Mercury’s weak magnetic field.
Lifshitz transition underlying the metamagnetic transition of UPt3
Authors: McCollam A , Fu Mingxuan , Julian S R
Published: November 2020

Comparing quantum oscillation measurements, dc magnetoresistance measurements, and Fermi surfaces obtained from LDA calculations, we argue that the metamagnetic transition of UPt3, which occurs at an applied field μ
◦
H

M
∼ 20 T, coincides with a Lifshitz transition at which an open orbit on the band 2 hole-like Fermi surface becomes closed for one spin direction. At low field, proximity of the Fermi energy to this particular van Hove singularity may have implications for the superconducting pairing potential of UPt3. In our picture the magnetization comes from non-linear spin-splitting of the heavy fermion bands. In support of this, we show that the non-linear field dependence of a particular quantum oscillation frequency can be fitted by assuming that the corresponding extremal Fermi surface area is proportional to the magnetization. In addition, below H

M
, we find in our LDA calculations a new, non-central orbit on band 1, whose non-linear behaviour explains a field-dependent frequency recently observed in magnetoacoustic quantum oscillation measurements.
Hysteretic magnetoresistance in nanowire devices due to stray fields induced by micromagnets
Authors: Jiang Y , de Jong E J , van de Sande V , Gazibegovic S , Badawy G , Bakkers E P A M , Frolov S M
Published: November 2020

We study hysteretic magnetoresistance in InSb nanowires due to stray magnetic fields from CoFe micromagnets. Devices without any ferromagnetic components show that the magnetoresistance of InSb nanowires commonly exhibits either a local maximum or local minimum at zero magnetic field. Switching of microstrip magnetizations then results in positive or negative hysteretic dependence as conductance maxima or minima shift with respect to the global external field. Stray fields are found to be in the range of tens of millitesla, comparable to the scale over which the nanowire magnetoresistance develops. We observe that the stray field signal is similar to that obtained in devices with ferromagnetic contacts (spin valves). We perform micromagnetic simulations which are in reasonable agreement with the experiment. The use of locally varying magnetic fields may bring new ideas for Majorana circuits in which nanowire networks require control over field orientation at the nanoscale.
First demonstration of high current canted-cosine-theta coils with Bi-2212 Rutherford cables
Authors: Garcia Fajardo L , Shen T , Wang X , Myers C , Arbelaez D , Bosque E , Brouwer L , Caspi S , English L , Gourlay S , Hafalia A , Martchevskii M , Pong I , Prestemon S
Published: November 2020

Future high energy physics colliders could benefit from accelerator magnets based on high-temperature superconductors, which may reach magnetic fields of up to 45 T at 4.2 K, twice the field limit of the two Nb-based superconductors. Bi2Sr2CaCu2O8-x (Bi-2212) is the only high-T
c cuprate material available as a twisted, multifilamentary and isotropic round wire. However, it has been hitherto unclear how an accelerator magnet can be fabricated from Bi-2212 round wires and whether high field quality can be achieved. This paper reports on the first demonstration of high current Bi-2212 coils using Rutherford cable based on a canted-cosine-theta (CCT) design and an overpressure processing heat treatment. Two Bi-2212 CCT coils, BIN5a and BIN5b, were made from a nine-strand Rutherford cable. Their electromagnetic design is identical, but they were fabricated differently: both coils underwent heat treatment in their aluminum–bronze mandrels, but unlike BIN5a that was impregnated with epoxy in its reaction mandrel, the conductor of BIN5b was transferred to a 3D printed Accura Bluestone mandrel after the heat treatment, a process attempted here for the first time, and was not impregnated. BIN5a reached a peak current of 4.1 kA with a self-field of 1.34 T in the bore. This corresponds to a wire engineering current density (J
e) of 912 A mm−2, which is two times that of BIN2-IL, a previous Bi-2212 CCT coil fabricated at LBNL, which used a six-around-one cable processed with the conventional 1 bar pressure melt processing. On the other hand, BIN5b reached 3.1 kA. The coils exhibited no quench training. All the quenches were thermal runaways that occurred at the same location. In addition, we report on the field quality and ramp-dependent hysteresis measurements taken during the test of BIN5a at 4.2 K. Overall, our results demonstrate that the CCT technology is a route that should be further investigated for making high field, potentially quench training free dipole magnets with Bi-2212 cables.
Continuous narrowband lasing with coherently driven V-level atoms
Authors: Hotter Christoph , Plankensteiner David , Ritsch Helmut
Published: November 2020

Simultaneous strong coherent pumping of the two transitions of a V-level atom with very different decay rates has been predicted to create almost perfect inversion on the narrower transition. Using the example of the blue and red transitions in Strontium we show that for suitable operating conditions the corresponding resonant gain can be used to continuously operate a laser on the narrow transition. In particular, for a strong detuning of the pump field with respect to the narrow transition, coherent laser emission occurs close to the bare atomic transition frequency exhibiting only a negligible contribution from coherent pump light scattered into the lasing mode. Calculations of the cavity output spectrum show that the resulting laser linewidth can get much smaller than the bandwidth of the pump light and even the natural linewidth of the narrow atomic transition. Its frequency is closely tied to the atomic transition frequency for properly chosen atom numbers. Simulations including atomic motion show Doppler cooling on the strong transition with minor motion heating on the lasing transition, so that continuous laser operation in the presence of a magneto-optical trap should be possible with current experimental technology.
Asymmetric broadening and blue shift of the stimulated Raman scattering spectrum in water under chirped picosecond laser pulse train excitation
Authors: Pershin Sergey M , Shashkov Evgeny V , Vorobiev Nikolay S , Nikitin Sergey P , Grishin Mikhail Ya , Komel’Kov Anton S
Published: November 2020

For the first time, we have revealed an asymmetric broadening and a 35 cm−1 blue shift (up to 3400 cm−1) of the stimulated Raman scattering OH band in water under chirped picosecond pulse train excitation (pulse duration ∼60 ps with 8 ns interval between pulses) while increasing the train length to 25 pulses. From the observed broadening and shift of the OH band centroid, a lower estimate (≥8 ns) of molecular complexes spectral states relaxation time at room temperature was obtained.
A compact stereotactic system for image-guided surgical intervention
Authors: Rusheen Aaron E , Barath Abhijeet S , Goyal Abhinav , Barnett J Hudson , Gifford Benjamin T , Bennet Kevin E , Blaha Charles D , Goerss Stephan J , Oh Yoonbae , Lee Kendall H
Published: November 2020

Objective. Stereotactic technology enables fine navigation to small structures in the human body. While current stereotactic systems facilitate accurate targeting, they are mechanically cumbersome and limited in scope. Here, we hypothesized that a stereotactic system could be developed with a reduced footprint while maintaining broad targeting capabilities in order to improve versatility in frame placement location and surgical workflow. Approach. We designed a stereotactic system around the center-of-arc principle, with mechanical properties that would enable a compact design and ample targeting and trajectory maneuverability. To examine the opportunity for a low-cost rapidly-deployable system we developed two fabrication variants, one using three dimensional (3D)-printing and the other using conventional machining. Mechanical and image-guided accuracies were tested in phantom studies using magnetic resonance imaging (MRI) and computed tomography. Using human cadaver head specimens, we assessed the system’s surgical workflow and its ability to reliably and accurately implant electrodes in deep brain stimulation (DBS) surgery. Main results. We developed a small 7.7 × 5.4 cm2 device platform that rigidly mounts to curvilinear bone and supports the attachment of surgical instrumentation. Attachment of two surgical instruments, an imaging localizer and a compact targeting device, demonstrated successful MRI-guided intervention in phantom studies with a vector error of 1.79 ± 0.41 mm. Evaluation of the 3D-printed system for DBS surgery confirmed ease of device platform attachment and instrument functionality, as well as demonstrated a surgical targeting accuracy of 1.83 ± 0.15 mm. In addition, we found the surgical time to be 78.3 ± 5.4 min for bilateral electrode implantation. Significance. We developed a light and compact stereotactic system whose accuracy is on par with those used clinically. This technology is suitable for clinical translation and its flexibility in positioning will seamlessly expand the capabilities for stereotaxy to treat a wide range of conditions, both within neurosurgery and beyond.
Development of Vertical Cavity Surface Emitting Laser Modulation for Data Communication
Authors: Cao Yixin
Published: November 2020

This paper includes some basic knowledge of VCSEL and reviews some researches focusing on development of modulation characteristics in data communication of 850nm, 980nm, 1060nm and 1100nm VCSEL, which is helpful to researchers who are studying in this field. The popular modulation in data communication VCSEL is also mentioned in this paper. There are still some difficulties in the modulation of VCSEL-based links directly, which may be solved by modulating relaxation-oscillation frequency of VCSEL in the near future.
The development of low toxic and high efficient solar cells
Authors: Liu Yang
Published: November 2020

Since the perovskite battery was put forward in 2009 for the first time, it is widely believed that it may bring huge influence on the reform of the next generation of solar cells. However, the lead element that are widely used in perovskite battery has strong toxicity which determines that it cannot be widely used in industrial production. Therefore, scientific researchers are trying to replace the lead element with some nontoxic elements or the elements with low toxicity like tin, germanium, bismuth and antimony and so on. Although the photoelectric conversion efficiency of these lead-free perovskite is greatly lower than that of lead-base perovskite, researchers already pay great attention on lead free materials and they have achieved remarkable results. The paper mainly introduces the research situation and development prospect of lead-free perovskite material and related devices.
The Exploration and Outlook of Two-Dimensional Perovskites
Authors: Tong Yi
Published: November 2020

Owing to the low cost and high efficiency in power conversion, perovskites have become a popular material for solar cells. Different from three-dimensional (3D) perovskites, two-dimensional (2D) perovskites tend to acquire high stability and high resistance to moisture. In addition, while lead is a commonly used B cation in 2D perovskites, it brings serious environmental damage. Therefore, people have been trying to replace lead (Pb) with tin (Sn), which is an almost harmless metal, in perovskites. This paper talks about the latest developments of 2D perovskites, as well as their prospect and future research directions.
Design of control and frequency conversion speed regulation system for mine fan
Authors: Zhang Hong-kui , Zhang Qiu-lin , Zhe Wang , Zhang De-peng , Wang Ming
Published: November 2020

In order to improve the accuracy and stability of the control system of mine fan, the control and frequency conversion speed regulation system of mine fan was developed based on PLC. Based on the analysis on control technology for mine fan, puts forward the inverter, soft start double mode control strategy, combined with the design of PLC control system hardware circuit and software program, the realization of mine fan starting and soft start, reasonable speed regulating, stop running process control, at the same time have the parameters such as voltage, current detection and fault protection function.
Simulation analysis on fatigue life of escalator main drive chain
Authors: Liu Xiaochang , Ren Facai , Xue Jiai , Ouyang Huiqing
Published: November 2020

This paper analyzes the fatigue life of the main drive chain of escalator in subway station. By analyzing the force of the main drive chain, the maximum and minimum force values of the main drive chain are obtained. The fatigue life of the main drive chain is analyzed based on the stress and fluctuating load, and the fatigue life of the escalator main drive chain in the subway station is obtained.
Based on Adam Optimization Algorithm: Neural Network Model for Auto Steel Performance prediction
Authors: Pengtao Wang
Published: November 2020

Neural network is optimized using the Adam algorithm, which introduces the first-order and second-order momentum of gradient. At the same time, learning rate is dynamically adjusted to different training stages to avoid the network from slow converging or oscillating. The three-layer neural network model is trained with a 5000 samples data set for HSLA steel performance prediction. The result shows that: compared with the traditional SGD algorithm, Adam shows efficient and stable training characteristics. After 742 epochs with initial learning rate of 0.001, the mean square error (MSE) of training set and validation set are below 90. On a data set consisting of 50 new samples, the prediction error of the yield strength and tensile strength on test set are less than 19MPa and 22MPa respectively, and the elongation prediction error is less than 3.1%.
A Magnetic Dipole Resonator for Magnetic Coupled Resonance Wireless Power Transmission
Authors: Yang Cheng , Hua Xuehui
Published: November 2020

This paper proposes a magnetic dipole structure Resonator for the magnetic coupled resonance wireless power transmission (WPT). The various characteristics are investigated by using simulations. To investigate the advantage of the proposed structure coil, a same geometric size traditional single-layer spiral coil is used for the power transfer characteristics Comparison. Due to the proposed structure, if the magnetic dipole resonator needs to be resonated at the same frequency with the traditional spiral coil, the larger number of turns is needed. This causes the resistance of loss to dramatically increase, thus decreasing the power transfer efficiency. To solve this problem, the tightly coupled parallel-connected coil structure was used. Depending on the characteristics of the tightly coupled parallel-connected coil structure the proposed magnetic dipole resonator can offer significantly reduced resistance with very little self-inductance loss. Simulation results show that compare to the same resonance frequency traditional single-layer spiral coil, a magnetic dipole resonator contributed by the tightly coupled parallel-connected coil structure can increase the Q factor by approximately 54.3%. Moreover, the simulation evaluation results confirmed that the proposed resonator can also dramatically improves the system power transfer flexibility performance.
Design of Plastic Injection Mould for Plastic Bracket
Authors: Ying Wang , Xiaocheng Li , Feng Zhou
Published: November 2020

The side core pulling mechanism of “fixed mold lifer+T-type lift guide block” is adopted for the fixed mold of bracket, and the side core pulling mechanism of “angle pin+slide” and “angle pin+slide+T-type guide block” side core pulling mechanism is adopted for the movable mold of bracket. The gating system adopts the sub gate, the inner reinforcing rib is formed by moving mold insert, and the ejection system is the form of ejector pin+blade ejector pin. It provides a good reference for the design of similar moulds.
Application of core-shell materials in glucose detection
Authors: Cao Lei
Published: November 2020

The development of materials science can make people control material composition morphology through various means. The Core-shell nanoparticles is one of them. According to the adjustment of the shell and the core in a reasonable manner, we were able to prepare different kinds of personalized function materials. Therefore, it has a wide range of application in various fields. This paper focuses on the subdivision of glucose detection, and discusses the successful application of composite core-shell nanoparticles of metal materials and non-metal materials in glucose detection, as well as some existing problems that still need to be solved.
Structural simulation analysis of a certain vehicle type disc brake based on ANSYS Workbench
Authors: Cui Changqing , Liu Na , Bei Taixue , Luo Wei
Published: November 2020

Taking the disc brake as the research object, the three-dimensional model established by Solidworks is imported into ANSYS Workbench, and its strength and modal simulation analysis are carried out. Taking the disc brake as the research object, the 3D model established by SolidWorks is imported into ANSYS Workbench, and the strength and modal simulation analysis are carried out then. Using the maximum stress point and maximum deformation position under the emergency braking state, combined with the results of modal analysis cloud chart, the resonance range is verified by comparing with the natural frequency, which provides reference for the actual tests and structural improvement.
The influence of microstructure on CTOD fracture toughness of DZ125 base metal and brazed joint
Authors: Ma Wenbin , Bai Xue , Luo Hongyun , Yang Xiaoguang
Published: November 2020

The microstructure of the base metal zone and the weld zone of the DZ125 directionally solidified nickel-based superalloy brazed joint is studied by means of scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and optical microscope. The CTOD fracture toughness of the base metal zone and the weld zone at 950 °C was tested respectively. The results show that the microstructure of the DZ125 alloy base metal grows with dendrites, the arrangement of the dendrites is close, the divergence angle is small, the dendrites are distributed with a uniform and fine γ′ phase, script-shaped MC carbides and petal-shaped γ/γ′ eutectic phases are distributed in the inter-dendrite zone. The uniform γ′ phase is distributed in the weld zone. At 950 °C, the CTOD fracture toughness of base metal and brazed joint is 0.080 mm and 0.048 mm, respectively. The fracture toughness of the base metal is higher than that of the brazed joint. The fracture morphology shows that the base metal has good toughness at 950 °C, while the weld zone has poor toughness at this temperature. It can be inferred that the long needle-shaped M6C carbides will weaken the structure performance.
Finite element analysis of a vehicle diesel engine crankshaft
Authors: Liu Fengliang , Zheng Zhongcai , WeiLuo  , Han Dongyue , Zhang Yifan
Published: November 2020

The crankshaft is the largest moving part in the engine and one of the most important parts in the engine. It bears the force transmitted from the connecting rod and converts this force into torque. The working conditions of the crankshaft are harsh, and its stress conditions are quite complicated. The stress concentration phenomenon is quite serious under the effect of bending and torsion loads, especially in the rounded transition area from the crank to the journal. In addition, the crankshaft has a significant impact on the overall size, weight, reliability, and manufacturing cost of the engine Therefore, the fatigue strength, stiffness, and wear resistance of the journal must be strictly checked and analyzed during the design of the crankshaft. In this paper, the finite element method is used as the main research method to analyze the static strength of a diesel engine crankshaft. The pre-processing software is used to optimize the topology of the crankshaft 1/2 single turn and the tetrahedral meshing. Then the finite element analysis software is imported to set the boundary Condition and apply the load, and finally submit the calculation. According to the working conditions, the crank pin load and the main journal support reaction force are calculated. Through the analysis of the results of crankshaft statics simulation, the weak links of the stress distribution of the crankshaft under dangerous conditions are found, which provides a theoretical basis for the structural design of the crankshaft.