bluuebunny/crossref_metadata_2025 huggingface dataset:
Learning the relationship between nanoscale chemical patterning and hydrophobicity
Authors: Rego Nicholas B. , Ferguson Andrew L. , Patel Amish J.
Published: November 2022

The hydrophobicity of proteins and similar surfaces, which display chemical heterogeneity at the nanoscale, drives countless aqueous interactions and assemblies. However, predicting how surface chemical patterning influences hydrophobicity remains a challenge. Here, we address this challenge by using molecular simulations and machine learning to characterize and model the hydrophobicity of a diverse library of patterned surfaces, spanning a wide range of sizes, shapes, and chemical compositions. We find that simple models, based only on polar content, are inaccurate, whereas complex neural network models are accurate but challenging to interpret. However, by systematically incorporating chemical correlations between surface groups into our models, we are able to construct a series of minimal models of hydrophobicity, which are both accurate and interpretable. Our models highlight that the number of proximal polar groups is a key determinant of hydrophobicity and that polar neighbors enhance hydrophobicity. Although our minimal models are trained on particular patch size and shape, their interpretability enables us to generalize them to rectangular patches of all shapes and sizes. We also demonstrate how our models can be used to predict hot-spot locations with the largest marginal contributions to hydrophobicity and to design chemical patterns that have a fixed polar content but vary widely in their hydrophobicity. Our data-driven models and the principles they furnish for modulating hydrophobicity could facilitate the design of novel materials and engineered proteins with stronger interactions or enhanced solubilities.
Regulation of the DEAH/RHA helicase Prp43 by the G-patch factor Pfa1
Authors: Enders Marieke , Ficner Ralf , Adio Sarah
Published: November 2022

The DEAH/RHA helicase Prp43 remodels protein–RNA complexes during pre-messenger RNA (mRNA) splicing and ribosome biogenesis. The helicase activity and ATP turnover are intrinsically low and become activated by G-patch (gp) factors in the specific cellular context. The gp motif connects the helicase core to the flexible C-terminal domains, but it is unclear how this affects RecA domain movement during catalysis and the unwinding of RNA substrates. We developed single-molecule Förster Resonance Energy Transfer (smFRET) reporters to study RecA domain movements within Prp43 in real time. Without Pfa1(gp), the domains approach each other adopting predominantly a closed conformation. The addition of Pfa1(gp) induces an open state, which becomes even more prevalent during interaction with RNA. In the open state, Prp43 has reduced contacts with bound nucleotide and shows rapid adenosine diphosphate (ADP) release accelerating the transition from the weak (ADP) to the strong (apo) RNA binding state. Using smFRET labels on the RNA to probe substrate binding and unwinding, we demonstrate that Pfa1(gp) enables Prp43(ADP) to switch between RNA-bound and RNA-unbound states instead of dissociating from the RNA. ATP binding to the apo-enzyme induces the translocation along the RNA, generating the unwinding force required to melt proximal RNA structures. During ATP turnover, Pfa1(gp) stimulates alternating of the RecA domains between open and closed states. Consequently, the translocation becomes faster than dissociation from the substrate in the ADP state, allowing processive movement along the RNA. We provide a mechanistic model of DEAH/RHA helicase motility and reveal the principles of Prp43 regulation by G-patch proteins.
Modulation of cGAS-STING signaling by PPARα in a mouse model of ischemia-induced retinopathy
Authors: Ma Xiang , Wu Wenjing , Liang Wentao , Takahashi Yusuke , Cai Jiyang , Ma Jian-xing
Published: November 2022

In ischemic retinopathy, overactivated retinal myeloid cells are a crucial driving force of pathological angiogenesis and inflammation. The cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING) signaling are key regulators of inflammation. This study aims to investigate the association of cGAS-STING signaling with ischemic retinopathy and the regulation of its activation. We found that protein levels of cGAS and STING were markedly up-regulated in retinal myeloid cells isolated from mice with oxygen-induced retinopathy (OIR). Knockout of
Sting
and pharmacological inhibition of STING both alleviated retinal neovascularization (NV) and reduced retinal vascular leakage in OIR. Further,
Sting
knockout and STING inhibitor also alleviated leukocyte adhesion to retinal vasculature and infiltration into the retina as well as microglial activation in OIR. These results suggest that cGAS-STING signaling played a pathogenic role in retinal myeloid cell activation and NV in ischemic retinopathy. To identify the regulation of cGAS-STING signaling in OIR, we evaluated the role of transcription factor peroxisome proliferator-activated receptor α (PPARα). The results demonstrated that PPARα was down-regulated in OIR retinas, primarily in myeloid cells. Furthermore,
Pparα
knockout significantly up-regulated cGAS and STING levels in retinal CD11b
+
cells, while PPARα agonist inhibited cGAS-STING signaling and cytosolic mitochondrial DNA (mtDNA) release, a causative feature for cGAS activation. Knockout of
Sting
ameliorated retinal NV, hyperpermeability, and leukostasis in
Pparα
−/−
mice with OIR. These observations suggest that PPARα regulates cGAS-STING signaling, likely through mtDNA release, and thus, is a potential therapeutic target for ischemic retinopathy.
Titin force in muscle cells alters lattice order, thick and thin filament protein formation
Authors: Hessel Anthony L. , Ma Weikang , Mazara Nicole , Rice Paige E. , Nissen Devin , Gong Henry , Kuehn Michel , Irving Thomas , Linke Wolfgang A.
Published: November 2022

Skeletal muscle force production is increased at longer compared to shorter muscle lengths because of length-dependent priming of thick filament proteins in the contractile unit before contraction. Using small-angle X-ray diffraction in combination with a mouse model that specifically cleaves the stretch-sensitive titin protein, we found that titin cleavage diminished the length-dependent priming of the thick filament. Strikingly, a titin-sensitive, length-dependent priming was also present in thin filaments, which seems only possible via bridge proteins between thick and thin filaments in resting muscle, potentially myosin-binding protein C. We further show that these bridges can be forcibly ruptured via high-speed stretches. Our results advance a paradigm shift to the fundamental regulation of length-dependent priming, with titin as the key driver.
Reactive granulopoiesis depends on T-cell production of IL-17A and neutropenia-associated alteration of gut microbiota
Authors: Chen Xuanzhong , Hashimoto Daigo , Ebata Ko , Takahashi Shuichiro , Shimizu Yu , Shinozaki Ryuga , Hasegawa Yuta , Kikuchi Ryo , Senjo Hajime , Yoneda Kazuki , Zhang Zixuan , Harada Shinpei , Hayase Eiko , Ara Takahide , Ohigashi Hiroyuki , Iwakura Yoichiro , Nakamura Kiminori , Ayabe Tokiyoshi , Teshima Takanori
Published: November 2022

Granulopoiesis in the bone marrow adjusts cellular output as demand for neutrophils changes. Reactive granulopoiesis is induced by profound neutropenia, but its mechanism remains to be clarified. We herein explored its mechanisms using mouse models of syngeneic hematopoietic stem cell transplantation (SCT) and 5-fluorouracil-induced neutropenia. After SCT, T cell production of IL-17A was up-regulated. Neutrophil recovery was significantly delayed in IL-17A-deficient or T cell-deficient

RAG1
−/−

mice, and adoptive transfer of wild-type (
WT
) T cells facilitated neutrophil engraftment. Gut decontamination with oral antibiotics suppressed T cell production of IL-17A and impaired neutrophil recovery. Transplantation of fecal microbiota collected from neutropenic, not naive, mice promoted neutrophil recovery in these mice, suggesting that neutropenia-associated microbiota had a potential to stimulate reactive granulopoiesis. Our study uncovered a cross talk between gut microbiota and neutropenia after SCT and chemotherapy.
Dual amplification strategy turns TRPM2 channels into supersensitive central heat detectors
Authors: Bartók Ádám , Csanády László
Published: November 2022

The Ca
2+
and ADP ribose (ADPR)-activated cation channel TRPM2 is the closest homolog of the cold sensor TRPM8 but serves as a deep-brain warmth sensor. To unravel the molecular mechanism of heat sensing by the TRPM2 protein, we study here temperature dependence of TRPM2 currents in cell-free membrane patches across ranges of agonist concentrations. We find that channel gating remains strictly agonist-dependent even at 40°C: heating alone or in combination with just Ca
2+
, just ADPR, Ca
2+
+ cyclic ADPR, or H
2
O
2
pretreatment only marginally activates TRPM2. For fully liganded TRPM2, pore opening is intrinsically endothermic, due to ~10-fold larger activation enthalpy for opening (~200 kJ/mol) than for closure (~20 kJ/mol). However, the temperature threshold is too high (>40°C) for unliganded but too low (<15°C) for fully liganded channels. Thus, warmth sensitivity around 37°C is restricted to narrow ranges of agonist concentrations. For ADPR, that range matches, but for Ca
2+
, it exceeds bulk cytosolic values. The supraphysiological [Ca
2+
] needed for TRPM2 warmth sensitivity is provided by Ca
2+
entering through the channel’s pore. That positive feedback provides further strong amplification to the TRPM2 temperature response (Q
10
~ 1,000), enabling the TRPM2 protein to autonomously respond to tiny temperature fluctuations around 37°C. These functional data together with published structures suggest a molecular mechanism for opposite temperature dependences of two closely related channel proteins.
Inflammatory platelet production stimulated by tyrosyl-tRNA synthetase mimicking viral infection
Authors: Morodomi Yosuke , Kanaji Sachiko , Sullivan Brian M. , Zarpellon Alessandro , Orje Jennifer N. , Won Eric , Shapiro Ryan , Yang Xiang-Lei , Ruf Wolfram , Schimmel Paul , Ruggeri Zaverio M. , Kanaji Taisuke
Published: November 2022

Platelets play a role not only in hemostasis and thrombosis, but also in inflammation and innate immunity. We previously reported that an activated form of tyrosyl-tRNA synthetase (YRS
ACT
) has an extratranslational activity that enhances megakaryopoiesis and platelet production in mice. Here, we report that YRS
ACT
mimics inflammatory stress inducing a unique megakaryocyte (MK) population with stem cell (Sca1) and myeloid (F4/80) markers through a mechanism dependent on Toll-like receptor (TLR) activation and type I interferon (IFN-I) signaling. This mimicry of inflammatory stress by YRS
ACT
was studied in mice infected by lymphocytic choriomeningitis virus (LCMV). Using Sca1/EGFP transgenic mice, we demonstrated that IFN-I induced by YRS
ACT
or LCMV infection suppressed normal hematopoiesis while activating an alternative pathway of thrombopoiesis. Platelets of inflammatory origin (Sca1/EGFP
+
) were a relevant proportion of those circulating during recovery from thrombocytopenia. Analysis of these “inflammatory” MKs and platelets suggested their origin in myeloid/MK-biased hematopoietic stem cells (HSCs) that bypassed the classical MK-erythroid progenitor (MEP) pathway to replenish platelets and promote recovery from thrombocytopenia. Notably, inflammatory platelets displayed enhanced agonist-induced activation and procoagulant activities. Moreover, myeloid/MK-biased progenitors and MKs were mobilized from the bone marrow, as evidenced by their presence in the lung microvasculature within fibrin-containing microthrombi. Our results define the function of YRS
ACT
in platelet generation and contribute to elucidate platelet alterations in number and function during viral infection.
A diminished hydrophobic effect inside the GroEL/ES cavity contributes to protein substrate destabilization
Authors: Korobko Ilia , Eberle Robin Benjamin , Roy Mousam , Horovitz Amnon
Published: November 2022

Confining compartments are ubiquitous in biology, but there have been few experimental studies on the thermodynamics of protein folding in such environments. Recently, we reported that the stability of a model protein substrate in the GroEL/ES chaperonin cage is reduced dramatically by more than 5 kcal mol
−1
compared to that in bulk solution, but the origin of this effect remained unclear. Here, we show that this destabilization is caused, at least in part, by a diminished hydrophobic effect in the GroEL/ES cavity. This reduced hydrophobic effect is probably caused by water ordering due to the small number of hydration shells between the cavity and protein substrate surfaces. Hence, encapsulated protein substrates can undergo a process similar to cold denaturation in which unfolding is promoted by ordered water molecules. Our findings are likely to be relevant to encapsulated substrates in chaperonin systems, in general, and are consistent with the iterative annealing mechanism of action proposed for GroEL/ES.
Shear transformations in metallic glasses without excessive and predefinable defects
Authors: Zhang Zhen , Ding Jun , Ma Evan
Published: November 2022

Plastic flow in metallic glasses (MGs) is known to be mediated by shear transformations (STs), which have been hypothesized to preferentially initiate from identifiable local “defect” regions with loose atomic packing. Here we show that the above idea is incorrect, i.e., STs do not arise from signature structural defects that can be recognized
a priori
. This conclusion is reached via a realistic MG model obtained by combining molecular dynamics (MD) and Monte Carlo simulations, achieving liquid solidification at an effective cooling rate as slow as 500 K/s to approach that typical in experiments for producing bulk MGs. At shear stresses before global yielding, only about 2% of the total atoms participate in STs, each event involving typically ~10 atoms. These observations rectify the excessive content of “liquid-like regions” retained from unrealistically fast quench in MD-produced glass models. Our findings also shed light on the indeterministic aspect of the ST sites/zones, which emerge with varying spatial locations and distribution depending on specific mechanical loading conditions.
Long-range dependence and extreme values of precipitation, phosphorus load, and Cyanobacteria
Authors: Carpenter Stephen R. , Gahler Mark R. , Kucharik Christopher J. , Stanley Emily H.
Published: November 2022

Extreme daily values of precipitation (1939–2021), discharge (1991–2021), phosphorus (P) load (1994–2021), and phycocyanin, a pigment of Cyanobacteria (June 1–September 15 of 2008–2021) are clustered as multi-day events for Lake Mendota, Wisconsin. Long-range dependence, or memory, is the shortest for precipitation and the longest for phycocyanin. Extremes are clustered for all variates and those of P load and phycocyanin are most strongly clustered. Extremes of P load are predictable from extremes of precipitation, and precipitation and P load are correlated with later concentrations of phycocyanin. However, time delays from 1 to 60 d were found between P load extremes and the next extreme phycocyanin event within the same year of observation. Although most of the lake’s P enters in extreme events, blooms of Cyanobacteria may be sustained by recycling and food web processes.
Follicle cell contact maintains main body axis polarity in the Drosophila melanogaster oocyte
Authors: Milas Ana , de-Carvalho Jorge , Telley Ivo A.
Published: November 2022

In Drosophila melanogaster, the anterior–posterior body axis is maternally established and governed by differential localization of partitioning defective (Par) proteins within the oocyte. At mid-oogenesis, Par-1 accumulates at the oocyte posterior end, while Par-3/Bazooka is excluded there but maintains its localization along the remaining oocyte cortex. Past studies have proposed the need for somatic cells at the posterior end to initiate oocyte polarization by providing a trigger signal. To date, neither the molecular identity nor the nature of the signal is known. Here, we provide evidence that mechanical contact of posterior follicle cells (PFCs) with the oocyte cortex causes the posterior exclusion of Bazooka and maintains oocyte polarity. We show that Bazooka prematurely accumulates exclusively where posterior follicle cells have been mechanically detached or ablated. Furthermore, we provide evidence that PFC contact maintains Par-1 and oskar mRNA localization and microtubule cytoskeleton polarity in the oocyte. Our observations suggest that cell–cell contact mechanics modulates Par protein binding sites at the oocyte cortex.
Continuous-Mixture Autoregressive Networks Learning the Kosterlitz-Thouless Transition
Authors: Wang Lingxiao , Jiang Yin , He Lianyi , Zhou Kai
Published: November 2022

We develop deep autoregressive networks with multi channels to compute many-body systems with continuous spin degrees of freedom directly. As a concrete example, we demonstrate the two-dimensional XY model with the continuous-mixture networks and rediscover the Kosterlitz–Thouless (KT) phase transition on a periodic square lattice. Vortices characterizing the quasi-long range order are accurately detected by the generative model. By learning the microscopic probability distributions from the macroscopic thermal distribution, the networks are trained as an efficient physical sampler which can approximate the free energy and estimate thermodynamic observables unbiasedly with importance sampling. As a more precise evaluation, we compute the helicity modulus to determine the KT transition temperature. Although the training process becomes more time-consuming with larger lattice sizes, the training time remains unchanged around the KT transition temperature. The continuous-mixture autoregressive networks we developed thus can be potentially used to study other many-body systems with continuous degrees of freedom.
Nonlinear Optomechanically Induced Transparency in a Spinning Kerr Resonator
Authors: Jiang Ya-Jing , Zhao Xing-Dong , Xia Shi-Qiang , Yang Chun-Jie , Liu Wu-Ming , Zhu Zun-Lue
Published: November 2022

We theoretically study optomechanically induced transparency in a spinning Kerr-nonlinear resonator. The interplay between the optical Kerr effect and the Sagnac effect provides a flexible tool for modifying the optomechanically induced transparency windows of the signal comparing to the system of a single spinning resonator. It is found that the system will exhibit distinct transparency phenomenon and fast-to-slow light effects. More importantly, a symmetric transparency window appears by adjusting the rotation-induced Sagnac frequency shift to compensate for the Kerr-induced frequency shift. These results open up a new way to explore novel light propagation of optomechanically induced transparency devices in spinning resonators with Kerr nonlinearity.
Convergence analysis of inexact Newton–Landweber iteration under Hölder stability
Authors: Xia Yuxin , Han Bo , Fu Zhenwu
Published: November 2022

In this paper, we focus on a class of inverse problems with Lipschitz continuous Fréchet derivatives both in Hilbert spaces and Banach spaces. The convergence and convergence rate of the inexact Newton–Landweber method (INLM) for such problems are presented under some assumptions. For the inverse problems in Hilbert spaces, we revisit the convergence result and the convergence rate of the INLM under Lipschitz condition and Hölder stability. Furthermore, the INLM for nonlinear inverse problems in Banach spaces is also considered. By using a Hölder stability corresponding to the Bregman distance, we derive the convergence property and convergence rate of the method.
Controlling quantum effects in enhanced strong-field ionisation with machine-learning techniques
Authors: Chomet H , Plesnik S , Nicolae D C , Dunham J , Gover L , Weaving T , Figueira de Morisson Faria C
Published: November 2022

We study non-classical pathways and quantum interference in enhanced ionisation of diatomic molecules in strong laser fields using machine learning techniques. Quantum interference provides a ‘bridge’, which facilitates intramolecular population transfer. Its frequency is higher than that of the field, intrinsic to the system and depends on several factors, for instance the state of the initial wavepacket or the internuclear separation. Using dimensionality reduction techniques, namely t-distributed stochastic neighbour embedding and principal component analysis, we investigate the effect of multiple parameters at once and find optimal conditions for enhanced ionisation in static fields, and controlled ionisation release for two-colour driving fields. This controlled ionisation manifests itself as a step-like behaviour in the time-dependent autocorrelation function. We explain the features encountered with phase-space arguments, and also establish a hierarchy of parameters for controlling ionisation via phase-space Wigner quasiprobability flows, such as specific coherent superpositions of states, electron localisation and internuclear-distance ranges.
The flashover of epoxy initiated by micron metal particles under DC voltage: phenomenon and mechanism
Authors: Qi Bo , Yang Zhuodong , Yang Xiao , Huang Meng , Gao Chunjia , Zhang Yi , Luo Yuan , Lu Licheng , Li Chengrong
Published: November 2022

Epoxy post-insulator is one of the key parts in SF6 gas-insulated DC wall bushing, which is irreplaceable in high voltage direct current transmission projects. Flashovers occur on post-insulators frequently, where a great number of tiny metal particles exist. The micron metal particles attached to the epoxy will change the insulation state of the surface. However, this relation between microstructure of material and macroscopic electrical properties on flashover would still arouse controversy. In order to study the effect of particles on the flashover characteristics, the particles generated from wear of spring in DC wall bushing were selected, the surface potential decay along surface and the DC flashover voltage of epoxy attached with particles were measured. The results show that the discrete particles could increase surface trap level by 0.025 eV under the effect of Van der Waals force. Furthermore, the deeper traps could capture the charge during the streamer development and inhibit the flashover, when the particle amount less than 500 per mm2. If the particles are more enough to form the continuous paths, these conductive paths could promote the streamer to propagate, which shortens the insulation distance, increases the electric field, and decreases the flashover voltage by 50% finally.
Design and application of ultra-thin focus transmitarray
Authors: Li Yinuo , Chen Juan , Shi Hongyu , Li Jianxing
Published: November 2022

An ultra-thin transmitarray (TA) working at 10 GHz with bandwidth of 1.15 GHz is proposed. The TA is designed by arranging two types of phase-shifting cells, with a thickness of only 2.8 mm (0.09 λ
0). The proposed focus TA has an obvious convergence effect for plane wave. It enhances the electric field intensity by 11.85 dB at the focus and can also transform the incident spherical wave into the plane wave. When a substrate cylinder antenna is loaded with the proposed TA, it reaches a peak gain of 17.8 dBi (increased by 8.8 dB) and its half-power beamwidth is reduced from 84° to 11°. The TA is fabricated and measured. The measured results are highly consistent with the simulated results, which validates the good performance of the TA.
Horizons: nuclear astrophysics in the 2020s and beyond
Authors: Schatz H , Becerril Reyes A D , Best A , Brown E F , Chatziioannou K , Chipps K A , Deibel C M , Ezzeddine R , Galloway D K , Hansen C J , Herwig F , Ji A P , Lugaro M , Meisel Z , Norman D , Read J S , Roberts L F , Spyrou A , Tews I , Timmes F X , Travaglio C , Vassh N , Abia C , Adsley P , Agarwal S , Aliotta M , Aoki W , Arcones A , Aryan A , Bandyopadhyay A , Banu A , Bardayan D W , Barnes J , Bauswein A , Beers T C , Bishop J , Boztepe T , Côté B , Caplan M E , Champagne A E , Clark J A , Couder M , Couture A , de Mink S E , Debnath S , deBoer R J , den Hartogh J , Denissenkov P , Dexheimer V , Dillmann I , Escher J E , Famiano M A , Farmer R , Fisher R , Fröhlich C , Frebel A , Fryer C , Fuller G , Ganguly A K , Ghosh S , Gibson B K , Gorda T , Gourgouliatos K N , Graber V , Gupta M , Haxton W C , Heger A , Hix W R , Ho W C G , Holmbeck E M , Hood A A , Huth S , Imbriani G , Izzard R G , Jain R , Jayatissa H , Johnston Z , Kajino T , Kankainen A , Kiss G G , Kwiatkowski A , La Cognata M , Laird A M , Lamia L , Landry P , Laplace E , Launey K D , Leahy D , Leckenby G , Lennarz A , Longfellow B , Lovell A E , Lynch W G , Lyons S M , Maeda K , Masha E , Matei C , Merc J , Messer B , Montes F , Mukherjee A , Mumpower M R , Neto D , Nevins B , Newton W G , Nguyen L Q , Nishikawa K , Nishimura N , Nunes F M , O’Connor E , O’Shea B W , Ong W-J , Pain S D , Pajkos M A , Pignatari M , Pizzone R G , Placco V M , Plewa T , Pritychenko B , Psaltis A , Puentes D , Qian Y-Z , Radice D , Rapagnani D , Rebeiro B M , Reifarth R , Richard A L , Rijal N , Roederer I U , Rojo J S , J S K  , Saito Y , Schwenk A , Sergi M L , Sidhu R S , Simon A , Sivarani T , Skúladóttir Á , Smith M S , Spiridon A , Sprouse T M , Starrfield S , Steiner A W , Strieder F , Sultana I , Surman R , Szücs T , Tawfik A , Thielemann F , Trache L , Trappitsch R , Tsang M B , Tumino A , Upadhyayula S , Valle Martínez J O , Van der Swaelmen M , Viscasillas Vázquez C , Watts A , Wehmeyer B , Wiescher M , Wrede C , Yoon J , Zegers R G T , Zermane M A , Zingale M
Published: November 2022

Nuclear astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper summarizes progress and status of the field, the new open questions that have emerged, and the tremendous scientific opportunities that have opened up with major advances in capabilities across an ever growing number of disciplines and subfields that need to be integrated. We take a holistic view of the field discussing the unique challenges and opportunities in nuclear astrophysics in regards to science, diversity, education, and the interdisciplinarity and breadth of the field. Clearly nuclear astrophysics is a dynamic field with a bright future that is entering a new era of discovery opportunities.
Dynamic collaboration in a crisis: creating a low-cost ventilator and test facility
Authors: Morris Jean , Schofield Joshua , Bull Chris , Knott Andy , Farrow-Dunn Frederick , Proctor Paul , Shore Paul
Published: November 2022

During the initial stages of the COVID-19 pandemic a major concern was the shortage of ventilators. Engineering initiatives were started to mitigate this concern. This article details the response at the National Physical Laboratory (NPL) to this potential shortage. The technologies and product development behind NPL’s PocketVent ventilator, by a team working remotely amidst a crisis, are explored. Underpinning the product was the creation of a traceable test facility, that allowed the initial three prototype devices to be narrowed to one. PocketVent was created within five months and offers pressure and volume controlled ventilation, with a clear road-map to implement constant-pressure mode, alongside a comprehensive documentation pack. The team were recipients of the Royal Academy of Engineering’s President’s Special Award for Pandemic Service.
Fourier analysis of periodic signals using an Arduino-based low-cost portable setup
Authors: Saxena Aparna , Saxena Anjali , Bharti Rupin , Nayak Harish , Kapoor Akanksha , Amayur Shabeeb , Saxena Raghvendra Sahai
Published: November 2022

The use of Arduino for studies in engineering applications and automation is quite common. The present paper reports the use of Arduino UNO R3 board for the Fourier analysis of various periodic waveforms. This is a very useful and cost effective idea for explaining and understanding Fourier series analysis. A real time Fourier component analysis of some standard input signals, such as square waves, sine waves, triangular waves and periodic pulses have been carried out in terms of the fundamental frequency and its harmonics. These results have been found to be the same as expected from the standard theoretical analysis. This method can be utilized effectively to teach the frequency components of a periodic waveform and demonstrate the utility of Fourier analysis to the students in the online mode of education, especially in remote places and villages.
Home experiments teaching for international students during pandemic
Authors: Luo Duan-bin
Published: November 2022

This paper introduces the home teaching of physics experiment course for international students in East China University of Science and Technology (ECUST) in the spring semester of 2022. After discussing the criteria for selecting the home experiments assigned to the students the chosen experiments are presented. Then we described the ways of home experiment teaching and investigated the students’ experimental performance and attitude through the questionnaire survey. The findings and the conclusions were drawn both form the reports submitted by students and from a questionnaire that students answered online after the completion of all experiments. We believe that home experimental teaching is a good educational proposal for the distance teaching challenge of physical experiment courses. At the same time, the home experiments also can enrich the contents of physical experiments demonstration in the classroom or laboratory.
Ultra-high field MRI: parallel-transmit arrays and RF pulse design
Authors: Williams Sydney N , McElhinney Paul , Gunamony Shajan
Published: November 2022

This paper reviews the field of multiple or parallel radiofrequency (RF) transmission for magnetic resonance imaging (MRI). Currently the use of ultra-high field (UHF) MRI at 7 tesla and above is gaining popularity, yet faces challenges with non-uniformity of the RF field and higher RF power deposition. Since its introduction in the early 2000s, parallel transmission (pTx) has been recognized as a powerful tool for accelerating spatially selective RF pulses and combating the challenges associated with RF inhomogeneity at UHF. We provide a survey of the types of dedicated RF coils used commonly for pTx and the important modeling of the coil behavior by electromagnetic (EM) field simulations. We also discuss the additional safety considerations involved with pTx such as the specific absorption rate (SAR) and how to manage them. We then describe the application of pTx with RF pulse design, including a practical guide to popular methods. Finally, we conclude with a description of the current and future prospects for pTx, particularly its potential for routine clinical use.
High frequency ultrasound vibrational shear wave elastography for preclinical research
Authors: Civale J , Parasaram V , Bamber JC , Harris EJ
Published: November 2022

Preclinical evaluation of novel therapies using models of cancer is an important tool in cancer research, where imaging can provide non-invasive tools to characterise the internal structure and function of tumours. The short propagation paths when imaging tumours and organs in small animals allow the use of high frequencies for both ultrasound and shear waves, providing the opportunity for high-resolution shear wave elastography and hence its use for studying the heterogeneity of tissue elasticity, where heterogeneity may be a predictor of tissue response. Here we demonstrate vibrational shear wave elastography (VSWE) using a mechanical actuator to produce high frequency (up to 1000 Hz) shear waves in preclinical tumours, an alternative to the majority of preclinical ultrasound SWE studies where an acoustic radiation force impulse is required to create a relatively low-frequency broad-band shear-wave pulse. We implement VSWE with a high frequency (17.8 MHz) probe running a focused line-by-line ultrasound imaging sequence which as expected was found to offer improved detection of 1000 Hz shear waves over an ultrafast planar wave imaging sequence in a homogenous tissue-mimicking phantom. We test the VSWE in an ex vivo tumour xenograft, demonstrating the ability to detect shear waves up to 10 mm from the contactor position at 1000 Hz. By reducing the kernel size used for shear wave speed estimation to 1 mm we are able to produce shear wave speed images with spatial resolution of this order. Finally, we present VSWE data from xenograft tumours in vivo, demonstrating the feasibility of the technique in mice under isoflurane sedation. Mean shear wave speeds in the tumours are in good agreements with those reported by previous authors. Characterising the frequency dependence of shear wave speed demonstrates the potential to quantify the viscoelastic properties of tumours in vivo.
Critical current degradation behavior of 7-filamentary Ba1−x
K
x
Fe2As2 tapes under uniaxial strain
Authors: Liu Xiao , Shi Yi , Liu Fang , Ma Hongjun , Liu Huajun , Zhou Chao , Song Yuntao , Gao Jian , Zhu Yanchang , Zhang Xianping , Wang Dongliang , Ma Yanwei , Zhang Zhan , Wei Shaoqing , Qin Jinggang
Published: November 2022

122-type iron-based superconductors (IBS) have attracted extensive attention due to their excellent performance. The 100 m class Ba1−x
K
x
Fe2As2 (Ba-122) 7-filamentary IBS tapes were successfully fabricated by the Institute of Electrical Engineering, Chinese Academy of Sciences. In this study, we have performed tests of the 7-filamentary Ba-122 short tape samples (Bas samples) and the 100 m class 7-filamentary Ba-122 tape samples (Ba100 samples) under various kinds of strain using U-shaped bending spring devices. Both types of samples were still reversible even when the applied compressive strain reached −0.65%. In addition, the reversible tensile strain limit of the Bas and Ba100 samples were 0.25% and 0.28%, which increased to 0.38% and 0.41% after considering the effect of the cooling process.
A scheme for multipartite entanglement distribution via separable carriers
Authors: Laneve Alessandro , McAleese Hannah , Paternostro Mauro
Published: November 2022

The ability to reliably distribute entanglement among the nodes of a network is an essential requirement for the development of effective quantum communication protocols and the realization of useful quantum networks. It has been demonstrated, in different contexts, that two remote systems can be entangled via local interactions with a carrier system that always remains in a separable state with respect to such distant particles. We develop a strategy for entanglement distribution via separable carriers that can be applied to any number of network nodes to achieve various entanglement distribution patterns. We show that our protocol results in multipartite entanglement, while the carrier mediating the process is always in a separable state with respect to the network. We provide examples showcasing the flexibility of our approach and propose a scheme of principle for the experimental demonstration of the protocol.
Inflation with massive spin-2 ghosts
Authors: Kubo Jisuke , Kuntz Jeffrey , Rezacek Jonas , Saake Philipp
Published: November 2022

We consider a generic model of quadratic gravity coupled to a single scalar and investigate the effects of gravitational degrees of freedom on inflationary parameters. We find that quantum corrections arising from the massive spin-2 ghost generate significant contributions to the effective inflationary potential and allow for a realization of the spontaneous breakdown of global scale invariance without the need for additional scalar fields. We compute inflationary parameters, compare the resulting predictions to well-known inflationary models, and find that they fit well within the Planck and BICEP/Keck collaboration's constraints on inflation.
The well-posedness of the Cauchy problem for self-interacting vector fields
Authors: Barausse Enrico , Bezares Miguel , Crisostomi Marco , Lara Guillermo
Published: November 2022

We point out that the initial-value (Cauchy) problem for self-interacting vector fields
presents the same well-posedness issues as for first-order derivative self-interacting scalar
fields (often referred to as k-essence). For the latter, suitable strategies have been employed
in the last few years to successfully evolve the Cauchy problem at the level of the infrared
theory, without the need for an explicit ultraviolet completion. We argue that the very same
techniques can also be applied to self-interacting vector fields, avoiding a number of issues and
“pathologies” recently found in the literature.
Revisiting the Magnetic Field Distribution of Normal Pulsars: Implications for the Multiple Origins for Neutron Stars
Authors: Zhang Jianwei , Zhang Chengmin , Li Di , Yang Wuming , Cui Xianghan , Ye ChangQing , Wang Dehua , Yang Yiyan , Bi Shaolan , Zhang Xianfei
Published: November 2022

In this study, we revisit the magnetic field (B-field) distribution of normal pulsars, motivated by the fact that the number of known pulsars has exceeded 3300. Here, we divided the normal pulsar samples into three subgroups by constant lines of characteristic age τ
ch, i.e., young, middle-aged, and old pulsars. We note that τ
ch is not used as the time indicator in this study; instead, it just served as cutting lines to divide the pulsar samples. Then, we applied several statistical tests, i.e., the Anderson–Darling, Shapiro–Wilk, Kolmogorov–Smirnov, and Mann–Whitney–Wilcoxon tests, to the selected normal pulsar samples (N = 1970) and to a data set of 32 neutron stars (NSs) in high-mass X-ray binaries (HMXBs) for comparison purposes. We obtained that (i) the conclusion on the characteristic B field (B
ch) log-normal distribution for the normal pulsars by the previous studies is no longer appropriate, while only young pulsars (N = 24, τ
ch < 15 kyr) follow a log-normal distribution, indicating that only the B
ch of young pulsars is close to real B fields. (ii) In the directly measured B-field range of NS-HMXBs (∼1012–1013 G), the B
ch of young pulsars (N = 15) and the real B fields of NS-HMXBs (N = 32) are inferred to be log-normal, and they are further verified to come from the same distribution, implying that there is no significant decay for real B fields, at least within the timescale of ∼10 Myr for normal pulsars. (iii) Statistically, young pulsars (N = 24) are inferred to be self-contained, suggesting that the initial spin period of pulsars is less than 515 ms. (iv) The B
ch distributions of three normal pulsar subsamples are different, hinting at the existence of multiple origins for NSs.
Integrated modelling of neon impact on JET H-mode core plasmas
Authors: Marin M. , Citrin J. , Giroud C. , Bourdelle C. , Camenen Y. , Garzotti L. , Ho A. , Sertoli M. , Contributors JET
Published: November 2022

Nuclear fusion reactor plasmas will need to exhaust a significant proportion of energy flux through radiative processes, to enable acceptable divertor loads. This can be obtained by line radiation from impurities, injected from the plasma edge. There are however limitations on the sustainable impurity content, since radiation from the core can lead to a deleterious electron heat sink. Moreover, dilution of the main ions reduces the available fuel. Simultaneously, impurities have an impact on the turbulent transport, both by dilution and by changes in the effective charge. Recent experiments at JET point towards an improvement in plasma confinement in neon seeded discharges with respect to purer equivalent plasmas. In this paper the impact of the impurities on the confinement is studied, isolating various effects. First-principle-based integrated modelling with the QuaLiKiz quasilinear turbulent transport model explains the improvement by a combination of higher pedestal temperature, increased rotation shear, and impurity-induced microturbulence stabilization. These results are optimistic with respect to the maximum impurity levels allowed in ITER and future reactors. Comparison between QuaLiKiz and higher fidelity gyrokinetics has exposed issues with QuaLiKiz impurity peaking predictions with rotation.
Effects of external kink and fishbone-like modes on energetic particle transport in tokamak plasmas
Authors: Wang Y.Q. , Hao G.Z. , Zou Y.P. , Liu Y.Q. , Chen W. , Yang G.M. , Meng G. , Miao Y.T. , Zhao Y.F. , Xia Y.B.
Published: November 2022

Transport and loss of beam injected energetic particles (EPs) due to three-dimensional perturbations, associated with the external kink (XK) instability and fishbone-like mode (FLM), are numerically investigated utilizing the guiding center following code ORBIT for static toroidal plasmas in HL-2A. The perturbation structure for the XK is computed by the MARS-F code and then mapped to the Boozer coordinates as defined in ORBIT. The simulation shows that the EP profile experiences a significant change in the middle of the plasma column, when the XK-induced radial magnetic field perturbation amplitude, normalized by the equilibrium field, exceeds a threshold value of about

10

−
2

. The EP transport is found to be dominated by a diffusion process instead of convection. Furthermore, by scanning the perturbation frequency as a free parameter while maintaining the XK mode structure (thus mimicking the FLM as observed in DIII-D and JT-60U tokamaks), redistribution and loss of EPs are found to be substantially enhanced due to strong resonances between the FLM and EPs, when the mode frequency exceeds a threshold value of ∼2 kHz for the case considered. For either XK or FLM, the response of passing EPs to the perturbation is dominant due to the assumed tangential neutral beam injection. Most lost EPs due to these instabilities are initially passing particles but are eventually lost through trapped orbits.
Design of a dual-standard gas flow facility with parallel structure
Authors: Wan Yong , Liu Li , Chen Hansong
Published: November 2022

The gas flow facility is mainly used to calibrate the indication error of the gas flow meter, A dual-standard gas flow facility with a parallel structure was developed. The bell jar and the gas standard flow meter can be used in parallel as a standard facility. The design principle, structure and calculation formula of the facility are described in the article. This facility can be used as a parallel dual-standard gas flow facility, and can be used as a back-blowing bell-jar gas flow standard facility or a back-blowing standard meter method gas flow standard facility, it only needs to switch the valve. The research and development of this facility enriches the detection means, expands the flow range, and reduces the pressure loss. It is verified by experiments that the detection results are reliable, the process operation is easy to apply, and it has a good promotion prospect.
Study on intrinsic defects of graphene oxide membranes for gas separation
Authors: Ren Guohua , Li Zheng , Sun Wei , Pan Ying , Liu Zhaoxian , Sun Lizhi
Published: November 2022

Gas membrane separation technology is a kind of mixed gas separation technology with low energy consumption, simple equipment, easy operation and no influence on the environment. Due to the special properties of graphene oxide (GO) membrane, GO membrane has become a research hotspot of mixed gas membrane separation technology. In this paper, A critical GO membrane thickness is demonstrated: when the thickness is less than 600nm, the conductance of the GO membrane is inversely exponential to the membrane thickness, but the conductance is inversely proportional to the thickness when the membrane is thicker than 600nm. Through the experimental study of Helium (He) through the GO membrane penetration, the gas through the GO membrane mathematical model is established. Through theoretical analysis, the transmission mechanism of gas through GO film is obtained, which provides support for GO membrane for gas separation in the future.
A tentative discussion on measurement uncertainty of electrical measuring instruments and device
Authors: Zhao Xia
Published: November 2022

This paper gives an elaboration on the source of uncertainty, general class and its difference with error, followed by detailed analysis and verification of a real case of measurement uncertainty. Taking a multi-function three-phase electrical measuring instrument calibration device as an example, the paper describes how to evaluate the uncertainty in measurement result of indication errors in mathematical model.
Small window cross-correlation accumulation time difference algorithm based on peak judgment method and generalized cross-correlation method
Authors: Zhou Huan , Ma Zhong , Chu Xiunan , Lu Jinbao , Yu Lu , Sun Yonggang , Chen Xu , Wu Xiaofeng
Published: November 2022

Based on peak judgment method and generalized correlation method, this paper proposes a new ultra high frequency partial discharge signal time difference algorithm. This algorithm avoids the defect that the traditional cross-correlation algorithm has a large correlation error for signals with lower amplitude. At the same time, by accumulating the correlation results of N groups of data, the influence of random interference of UHF PD signal on the correlation results is reduced. N times of correlation analysis were performed and correlation results were accumulated in a small area near the peak of the UHF PD signal, not only avoiding the deficiencies of the traditional peak judgment method that the peak value of the UHF PD signal is not easy to determine, but also minimizing the effect of PD white noise. In order to verify the effectiveness of the proposed algorithm, the time difference calculated by different algorithm are compared, and the results show that the proposed algorithm is superior to other existing algorithms.
Accumulation characteristics of free metallic particles in flowing transformer oil under uniform and non-uniform electric field
Authors: Wang Jintong , Men Hongyue , Huang Jingwei , Xiao Ji , Zhu Jinkang , Fan Wupeng , He Guangyu , Chen Peidong
Published: November 2022

Transformer oil is easily polluted by metal particles. Once the metal particles accumulate in the oil channel, the insulation performance of the equipment will be greatly reduced. In this paper, an oil circulation device was built and the accumulation characteristics of free metal particles in flowing transformer oil were carried out under uniform and non-uniform electric field. The images of particle accumulation process were captured by a high-speed camera. Simultaneously, we analysed the force conditions of particles in oil. And the accumulation mechanisms under different electric fields were discussed combined with the particle trajectories. It was reported that particle accumulation could be observed in static oil under both electric fields. The particle concentration between electrodes decreased gradually with time. However, when the transformer oil was flowing, the accumulation concentration of particles decreased significantly with the increase of flow velocity. The accumulation of metal particles was seriously damaged, even no longer occurred.