bluuebunny/crossref_metadata_2025 huggingface dataset:
Demagnetizing field-induced magnetocaloric effect in Gd
Authors: Badosa Quim , Mañosa Lluís , Vives Eduard , Planes Antoni , Weise Bruno , Beyer Lukas , Stern-Taulats Enric
Published: September 2023

We have studied the impact of demagnetizing fields on the magnetocaloric effect of commercial-grade gadolinium plates. Adiabatic temperature changes (ΔT) were measured for magnetic fields applied along the parallel and perpendicular directions of the plates. The differences in the obtained ΔT values were accounted for by differences in the internal field due to demagnetizing effects. A combination of calorimetric measurements under a magnetic field and thermometric measurements has enabled us to obtain Brayton cycles for the two different magnetic field orientations. It has been found that the refrigerant capacity for a Brayton cycle working at 1.6 T around room temperature reduces from RC=9.4 to RC=5.5 J kg−1 when the demagnetizing factor changes from ND = 0.035 to ND=0.928 for the parallel and perpendicular configurations, respectively. It has been shown that it is possible to obtain significant demagnetizing field-induced magnetocaloric effects by rotating the sample in a region of a constant applied magnetic field. The refrigerant capacity of a Brayton cycle around room temperature for a 1.6T constant applied magnetic field is RC=0.6 J kg−1. The feasibility of these demagnetizing field-induced effects has been confirmed by direct thermometric measurements, which reveal adiabatic temperature changes of 1 K when the sample is rotated between the perpendicular and parallel configurations.
A design method of high-compatibility horn for broad-bandwidth transducer
Authors: Fu Junfan , Lin Bin , Pei Tianhe , Sui Tianyi , Dong Baokun
Published: September 2023

Broad-bandwidth transducers are one of the main areas of focus for the development of power ultrasonic systems, which address the issues that the contactless transformer system cannot track transducer frequency and narrowband transducers are not compatible with different tools. This paper aims to investigate the potential capabilities of broad-bandwidth transducers in terms of compatibility with different horns and to propose a design method for highly compatible tools. The frequency equation of horn is nondimensionalized to calculate relative frequency errors δ. The effects of shape, dimensionless size, and order number on δ are investigated based on the equation. A compatibility range is proposed, and the relationship between it and the required relative bandwidth of the transducer is investigated. Various horns were designed, and the corresponding simulations, impedance measurements, and resonance experiments were conducted to explore the effects of these factors on δ, amplitude, and the quality factor Q. These experiments also verified the feasibility of using a broad-bandwidth transducer that is compatible with different tools. Finally, the application scenarios of the three horns are summarized based on a comparison of their matching ability, amplitude, operational stability, and compatibility range.
Controlling the piezoelectric properties in bulk BiFeO3–PbTiO3–Li0.5Bi0.5TiO3 ceramic by quenching and annealing
Authors: Tuluk Anton , van der Zwaag Sybrand
Published: September 2023

In the present work, we study the effect of quenching and annealing on the ferroelectric and piezoelectric properties at room temperature and elevated temperatures of a new ternary BiFeO3-PbTiO3-Li0.5Bi0.5TiO3 bulk piezo ceramic. While sacrificing part of the maximally obtainable piezoelectric constant value, using an optimal heat treatment, a quasi-stable value for the piezoelectric constant of 65 pC/N was obtained irrespective of the annealing temperature. All experimental results point to the direction of unusual defect behavior in this novel ternary system leading to a well-defined metastable state. The quenching and annealing process are completely reversible and can be used in combination with additional chemical modifications to tailor the properties of this new high-temperature piezoelectric ceramic to the intended use conditions.
The propagation of Alfvén wave in magnetized plasma sheath of hypersonic vehicles in near space
Authors: Xiong Jiawei , Yuan Kai , Tang Rongxin , Mao Mingyang , Deng Xiaohua
Published: September 2023

Hypersonic plasma sheath could shield communication signals, which results in the so-called “blackout.” Blackout is a major risk to the safety of re-entry vehicles and cruise hypersonic vehicles in near space. In this study, a propagation model of Alfvén waves in plasma sheaths is developed. The impacts of the external magnetic field, the wave frequency, and the boundary conductivity on the Alfvén attenuation were investigated. According to the simulation results, once the conductivity is close to the Alfvénic conductivity near the onboard antenna, the attenuation of Alfvén waves in the plasma sheath could reach its minimum. The total attenuation of the Alfvén wave in the plasma sheath decreases with the carrier frequency. Also, the attenuation decreases with increasing magnetic field strength.
Numerical study on similarity performance of geometric scaling of lean premixed swirl combustor
Authors: Xie Wenda , Shi Ting , Ge Bing , Zang Shusheng
Published: September 2023

This paper describes the use of experimentally validated computational fluid dynamics methods to study the similarity performance of various models scaled by the DaI criterion. First, the numerical method is validated by particle image velocimetry and CH* chemiluminescence data under the reaction state. Combustor prototypes and models are then simulated under different equivalence ratios (ERs) and swirl numbers (SWs) with the geometric scaling factor (Q) ranging from 0.1 to 1. When Q < 0.3, the reaction zone is obviously stretched. Changes in Q produce large deviations in the velocity distribution. Increasing either ER or SW increases the deviation in the velocity distribution in the outer shear region in front of the combustor but reduces that in the recirculation zone and jet zone at the back of the combustor. The scaling law changes with ER and SW. To distinguish whether the reaction flow field of a model maintains similarity with respect to the prototype, a novel concept called “degree of similarity” is proposed. The “non-similarity range” for geometric scaling factors under different conditions is further clarified. When ER = 0.55, the range of non-similarity of the combustion flow field is Q ≤ 0.3. As ER increases, the range of non-similar intervals decreases, and when ER reaches 0.95, the non-similarity range is Q ≤ 0.1. When SW = 0.42, the non-similarity range is Q ≤ 0.4, and when SW ≥ 0.42, the non-similarity range is Q ≤ 0.3.
Effects of atmospheric UV-O3 exposure of WSe2 on the properties of the HfO2/WSe2 interface
Authors: Sales Maria Gabriela , Mazzoni Alexander , Sarney Wendy L. , Leff Asher C. , Pearson Justin , Najmaei Sina , McDonnell Stephen
Published: September 2023

Transition metal dichalcogenides (TMDCs), such as semiconducting WSe2, are typically interfaced with a high-quality dielectric layer in device applications. The unreactive basal plane of TMDCs makes the standard technique for deposition of dielectric oxides, atomic layer deposition (ALD), challenging on TMDC surfaces. In this work, we make use of atmospheric ultraviolet–ozone (UV-O3) exposure of WSe2 to functionalize its surface and promote uniform ALD of HfO2. We report two classifications depending on the UV-O3 exposure time. Low exposures do not result in detectable WSe2 surface oxidation, while high exposures result in a self-limiting and amorphous tungsten oxyselenide top layer. Following ALD of HfO2, low exposure samples have an abrupt HfO2/WSe2 interface with no interfacial oxide, while high exposure results in an interfacial WO3 layer between the HfO2 and the WSe2, as well as evidence of two doping states observed in the underlying WSe2. Despite differences in the interface chemistry, both low and high exposures result in uniform and smooth HfO2 films directly deposited by ALD and a reduction in gate leakage through this HfO2 layer. We report that our atmospheric UV-O3 exposure technique on WSe2 is an avenue for allowing direct ALD of thin uniform oxide films on WSe2, and the UV-O3 exposure time provides unique tunability and flexibility in interface design within devices.
On the optimal design of staved water-lubricated bearings driven by tribo-dynamic mechanism
Authors: Tang Dongxing , Xiang Guo , Guo Juan , Cai Jianlin , Yang Tianyou , Wang Jiaxu , Han Yanfeng
Published: September 2023

In this study, a structural optimization method driven by tribo-dynamic mechanism is proposed for the staved water-lubricated bearings (SWLBs). To this end, a tribo-dynamic model considering mass conservation cavitation is established, and the accuracy of this model is verified by comparing it with the experimental and numerical results in published literature studies. The comparative studies emphasize the significant role of mass conservation cavitation on the tribo-dynamic responses of SWLBs under the mixed lubrication regime. Based on numerical simulations, the optimal stave structure for a specific working operation under heavy load condition is identified from the perspective of the tribo-dynamic mechanism. Furthermore, in order to evaluate the applicability of the proposed optimization method, the influences of key parameters, including the rotational speed, the radial clearance, and the surface roughness, on the optimization results are comparatively analyzed. The comparative results reveal that the optimal stave structure is highly dependent on the mentioned key parameters, and the optimal method is effective for a wide range of working conditions. Moreover, the effects of the stave parameters, including stave width and number, on tribo-dynamic characteristics of SWLBs are also investigated, suggesting a more comprehensive optimization scheme for SWLBs.
A new method for reactive constant pH simulations
Authors: Levin Yan , Bakhshandeh Amin
Published: September 2023

We present a simulation method that allows us to calculate the titration curves for systems undergoing protonation/deprotonation reactions—such as charged colloidal suspensions with acidic/basic surface groups, polyelectrolytes, polyampholytes, and proteins. The new approach allows us to simultaneously obtain titration curves both for systems in contact with salt and acid reservoir (semi-grand canonical ensemble) and for isolated suspensions (canonical ensemble). To treat the electrostatic interactions, we present a new method based on Ewald summation—which accounts for the existence of both Bethe and Donnan potentials within the simulation cell. We show that the Donnan potential dramatically affects the pH of a suspension. Counterintuitively, we find that in suspensions with a large volume fraction of nanoparticles and low ionic strength, the number of deprotonated groups can be 100% larger in an isolated system, compared to a system connected to a reservoir by a semi-permeable membrane—both systems being at exactly the same pH.
Topological slow light enhanced second harmonic generation in double-resonant topological photonic crystal
Authors: Hu Weipeng , Liu Chao , Guo Jun , Dai Xiaoyu , Wen Shuangchun , Xiang Yuanjiang
Published: September 2023

Generally, the second-harmonic generation and slow light of multi-band topological edge states (TESs) have been studied separately. Therefore, the influence of simultaneous slow light and topology protection on second-harmonic generation (SHG) is deficient. Here, we propose a high-efficiency SHG using dual-frequency TESs in topological photonic crystals (TPCs) with slow-light conditions. The wave vector matching condition and energy conservation condition (frequency doubling) can be achieved by adequately adjusting the overall structural parameters of TPCs. The double-resonant nonlinear interaction between two TESs is enabled using a square lattice TPC. Due to the topological localization of the TES and the long interaction time of slow-light effect, the energy densities of the fundamental wave and SHG are significantly increased. Consequently, the high intrinsic efficiency of SHG can be obtained in the order of 7.40 × 10−4. Our work opens new avenues for using topological protected and slow light enhanced nonlinear frequency conversion in a TPC system.
Current and voltage responsivity up to 110 GHz in GaN asymmetric nano-diodes
Authors: Íñiguez-de-la-Torre I. , Pérez-Martín E. , Artillan P. , Rochefeuille E. , Sánchez-Martín H. , Paz-Martínez G. , González T. , Mateos J.
Published: September 2023

The detection capability of GaN-based nano-diodes is measured up to 110 GHz in two configuration schemes: voltage and current responsivity. The ratio between both figures of merit allows one to extract the AC resistance of the diode, showing a very flat value in all the frequency spans. An optimization on the geometrical parameters is performed, finding that the narrower the channel, the higher the voltage responsivity, and the higher the number of channels in parallel, the higher the current responsivity. The expected dependence of the noise equivalent power with the width and number of channels is confirmed. The proposed configuration for best performance of these devices as RF detectors is to allocate the maximum number of channels in parallel and operate in a current responsivity mode.
Uniform space-charge-limited current for a two-dimensional planar emitter with nonzero monoenergetic initial velocity
Authors: Zhu Xiaojun , Sree Harsha N. R. , Garner Allen L.
Published: September 2023

While characterizing space-charge-limited current (SCLC) is important for numerous applications, no analytical solutions for SCLC with monoenergetic initial velocity exist for two-dimensional (2D) geometries. Here, we derive approximate closed-form solutions for uniform SCLC with monoenergetic emission of electrons in a 2D planar diode, where emission is restricted to a long patch of width W for electrodes separated by a distance D. We also derive a semiempirical approach for estimating the SCLC for these cases by treating the geometric and velocity correction factors as multiplicative corrections to the SCLC for a one-dimensional vacuum diode given by the Child–Langmuir (CL) law. We show that the SCLC for a finite patch with nonzero velocity can exceed the CL law by three orders of magnitude. The theoretically calculated SCLCs for various emission widths and initial velocities in the 2D diode agree well with particle-in-cell simulations using the over-injection method in XOOPIC; they agree with the semiempirical relationship for lower initial velocities. In the limit of high initial velocity, the geometry and velocity corrections to the CL law cannot be decoupled, invalidating the assumption of the semiempirical approach and causing it to diverge from the theoretical solution and XOOPIC simulations. These results provide valuable estimates for determining the onset of virtual cathode formation for photocathodes and thermionic cathodes, which operate in the over-injection regime to avoid beam quality degradation.
Performance study of a valveless piezoelectric pump with built-in semi-arc bluffbody antique tower channel
Authors: Hu Renhui , Wang Chensheng , Hou Yi , Hu Dianbin , He Lipeng
Published: September 2023

According to the bluffbody bypass effect, the irregular bluffbody can be used to improve the valveless piezoelectric pump. This paper designs a semi-arc bluffbody based on the bluffbody bypassing principle to alleviate the phenomenon of fluid backflow. The fluid passes through the shape of the antique tower to further enhance pumping efficiency. A positive fluid flow mechanism in the pump cavity is theoretically derived. The simulation of the velocity and pressure distribution in the tower-shaped channel of the pump cavity leads to the conclusion that the forward flow has better performance than the reverse flow, and the correctness of the theory is also verified. Experiments further proved that the volume of fluid in the forward direction was reduced by 10.8% when compared to the reverse direction. The study of the height of different semi-arc bluffbody and the angle of the tower trough shows that as the height and angle increase, the flow rate grows first and then reduces. The maximum flow rate is 243.83 ml/min when the bluffbody height is 4 mm and the channel angle is 20° (220 V, 85 Hz).
Killer defect responsible for reverse leakage current in halide vapor phase epitaxial (011)
β
-Ga2O3 Schottky barrier diodes investigated via ultrahigh sensitive emission microscopy and synchrotron x-ray topography
Authors: Sdoeung Sayleap , Otsubo Yuto , Sasaki Kohei , Kuramata Akito , Kasu Makoto
Published: September 2023

In this study, we identify the killer defect responsible for the reverse leakage in the halide vapor phase epitaxial (011) β-Ga2O3 Schottky barrier diode via ultrahigh sensitive emission microscopy, synchrotron x-ray topography, and scanning transmission electron microscopy. A polycrystalline defect was found to be causing a leakage current of −5.1 μA at a reverse bias of −50 V. They were distributed across the wafer with a density ranging from 10 to 103 cm−2. Cross-sectional scanning electron microscopy of the polycrystalline defect revealed domains with various crystal orientations accompanied by a (100)-oriented micro-crack and dislocations along the [010] direction.
On the chemistry of small waterbodies linked to marine aerosols and local geology on the Windmill Islands and mainland near Casey Station, Antarctica
Authors: De Deckker Patrick , Chivas Allan R. , Kiss Elmer , Mikkelson Nicole
Published: September 2023

Context In total, 43 shallow waterbodies were sampled in 1983 in the vicinity of Casey Station and nearby islands in Antarctica. The following physico-chemical parameters were obtained: water and air temperature, pH, conductivity, dissolved oxygen, plus major and minor elements. Aims To identify the physico-chemical characteristics of these waters and determine their origin, and calculate their mineral saturation indices. Methods Waters were analysed using standard methods, including for some elements, flame-atomic absorption spectrometry, spectrophotometry, ion chromatography and gravimetric determination. Mineral saturation indices were calculated using the PHREEQ program. Key results Water salinities were generally low and in the range of 120–1200 mg L−1 (total dissolved solids, TDS), except for one site connected to the sea, and four slightly saline sites. The Na/Cl, Cl/Br and Ca/SO4 ratios of several waters were in the vicinity of seawater ratios, implying a contribution of marine aerosols. However, the Mg/Ca ratio of most waters departed from the seawater ratio, plus there was concordance between the molar ratios of (Na + K)/(Ca + Mg) of many of the waters sampled and those calculated from rock geochemical analyses from diverse lithologies. Such chemical ‘provincialism’ appears to be dictated by rock composition. Nitrate and phosphate concentrations were high in the vicinity of penguin rookeries. Conclusions Two sources of ions are identified, one as marine aerosols as shown by three sets of ratios (Na/Cl, Cl/Br and Ca/SO4) with known marine values, and the other from the weathering of local rocks as shown by (Na + K)/(Ca + Mg) of the lake waters compared to the same ratios for the surrounding rocks. Only a few waterbodies have saturation levels for several carbonate minerals (calcite, aragonite, dolomite and rhodochrosite). Implications Future work is recommended for monitoring the waterbodies surrounding Casey Station as a result of the increased atmospheric CO2 concentration that has occurred over the past 40 years, and likely also with the cessation of building activities around Casey Station.
Novel acoustic lure methodology facilitates detection of the cryptic ghost bat at a landscape scale
Authors: Ruykys Laura , Hanrahan Nicola , Stokeld Danielle
Published: September 2023

Context The conservation of the threatened ghost bat (Macroderma gigas) is currently hampered by a lack of standardised survey methodology for detecting the species away from known roosts. The low amplitude of the species’ echolocation call, together with only sporadic production of social calls while foraging, means that acoustic detection is unreliable. However, the ghost bat is known to be physically responsive to full-spectrum playback of its own social calls when these are broadcast in close vicinity (~100 m) to known roosts. Aims Using a two-phase investigation, we aimed to establish whether playback could be used to detect ghost bats away from the roost, in open woodland habitat in the Northern Territory. Methods In phase one, a trial of paired (active treatment and control) call playback experiments was conducted at three distances (1 km, 2.5 km and 5 km) from four known roosts using the ghost bat’s ‘squabble’ social vocalisation. Call playback, distance, roost and moon phase were used as explanatory variables in an information-theoretic approach using generalised linear models. In phase two, a 65 010-ha survey area was broken into a grid of adjacent hexagons with centroids spaced 5 km apart; replicate surveys using call playback were conducted at each centroid. An occupancy model was used to determine detection probability for the method in the survey area. Key results Ghost bats were successfully detected. In phase one, one model had substantial support and this contained only one variable: that of the presence or absence of the ‘squabble’ vocalisation. In phase two, ‘hotspots’ of ghost bat activity were detected in a region for which records were scant and predominantly historical. The occupancy model identified that 72% of sites were occupied and established a detection probability of 0.505, which provided a cumulative probability of 0.75. Conclusions Our results show that call playback is a reliable method of detecting the cryptic and threatened ghost bat at a landscape scale in the Northern Territory. Implications We suggest that call playback could be used as a standardised survey technique across the range of the ghost bat.
Water scarcity exacerbates feral ungulate use of ephemeral savanna waterholes in northern Australia
Authors: Mihailou Helenna , Nimmo Dale G. , Massaro Melanie
Published: September 2023

Context Australian savannas evolved in the absence of hooved mammals and are therefore prone to disturbance from exotic ungulates. Several ungulate species have established feral populations in Australia’s northern savannas. Because most ungulate species have high water requirements, seasonal and interannual changes in water availability are likely to affect their behaviour and the extent of their impacts on native ecosystems. However, few studies have investigated how water scarcity affects feral ungulate use of waterpoints in Australia. Aims The aim of this study was to determine whether seasonal and interannual water scarcity affected the visitation behaviours of feral pigs, cattle and water buffalo at ephemeral savanna waterholes within Limmen National Park, Northern Territory, Australia. Methods We used motion-triggered wildlife cameras to study feral ungulate visitation and behaviour at 20 waterholes. Generalised linear mixed-effects models were used to investigate whether the number of visits, duration of visits and number of individuals visiting waterholes varied with year and dry season progression. We also investigated whether these factors affected the amount of time ungulates spent foraging, drinking and wallowing at waterholes. Key results All three species visited waterholes more often, for longer periods and in larger numbers during a drought year compared with an average rainfall year. Cattle and buffalo spent more time drinking from waterholes during the drought, and pigs and cattle spent longer periods foraging. Buffalo also wallowed more during the drought. Responses to dry season progression varied among species. Cattle visited waterholes more frequently, for longer durations and in larger herd sizes as the dry season progressed, whereas buffalo use did not change. Pigs only increased their visitation to waterholes when water scarcity was most extreme, at the end of the dry season during the drought. Conclusions Our results demonstrate that water scarcity exacerbates feral ungulate use of savanna waterholes. Management and control programs for feral ungulates in Australian savannas may benefit from targeting different species under specific water scarcity conditions. Implications Because climate change is predicted to reduce surface water availability in northern Australia, feral ungulate use of savanna waterholes may intensify, risking further biodiversity losses and irreversible ecosystem damage.
Cancer-associated fibroblasts influence Wnt/PCP signaling in gastric cancer cells by cytoneme-based dissemination of ROR2
Authors: Rogers Sally , Zhang Chengting , Anagnostidis Vasilis , Liddle Corin , Fishel Melissa L. , Gielen Fabrice , Scholpp Steffen
Published: September 2023

Cancer-associated fibroblasts (CAFs) are a crucial component in the tumor microenvironment influencing cancer progression. Besides shaping the extracellular matrix, these fibroblasts provide signaling factors to facilitate tumor survival and alter tumor behavior. In gastric cancer, one crucial signaling pathway influencing invasion and metastasis is the Wnt/Planar Cell Polarity (PCP) signaling. The crucial PCP ligand in this context is WNT5A, which is produced by the CAFs, and gastric cancer cells react upon this signal by enhanced polarized migration. Why gastric cancer cells respond to this signal is still unclear, as their expression level for the central WNT5A receptor, ROR2, is very low. Here, we show that CAFs display long and branched filopodia that form an extensive, complex network engulfing gastric cancer cells, such as the gastric cancer cell line AGS. CAFs have a significantly higher expression level of ROR2 than normal gastric fibroblasts and AGS cells. By high-resolution imaging, we observe a direct transfer of fluorescently tagged ROR2 from CAF to AGS cells by signaling filopodia, known as cytonemes. Surprisingly, we find that the transferred ROR2 complexes can activate Wnt/JNK signaling in AGS cells. Consistently, blockage of ROR2 function in the CAFs leads to reduced paracrine Wnt/JNK signaling, cell polarization, and migration of the receiving AGS cells. Complementary, enhanced migration via paracrine ROR2 transfer was observed in a zebrafish in vivo model. These findings demonstrate a fresh role for cytoneme-mediated signaling in the tumor microenvironment. Cytonemes convey Wnt receptors from CAFs to gastric cancer cells, allowing them to respond to Wnt/PCP signals.
Iditarod
, a
Drosophila
homolog of the Irisin precursor
FNDC5
, is critical for exercise performance and cardiac autophagy
Authors: Cobb Tyler , Hwang Irene , Soukar Michael , Namkoong Sim , Cho Uhn-Soo , Safdar Maryam , Kim Myungjin , Wessells Robert J. , Lee Jun Hee
Published: September 2023

Mammalian
FNDC5
encodes a protein precursor of Irisin, which is important for exercise-dependent regulation of whole-body metabolism. In a genetic screen in
Drosophila
, we identified
Iditarod
(
Idit
), which shows substantial protein homology to mouse and human
FNDC5
, as a regulator of autophagy acting downstream of Atg1/Atg13. Physiologically,
Idit
-deficient flies showed reduced exercise performance and defective cold resistance, which were rescued by exogenous expression of
Idit
. Exercise training increased endurance in wild-type flies, but not in
Idit
-deficient flies. Conversely, Idit is induced upon exercise training, and transgenic expression of
Idit
in wild-type flies increased endurance to the level of exercise trained flies. Finally,
Idit
deficiency prevented both exercise-induced increase in cardiac Atg8 and exercise-induced cardiac stress resistance, suggesting that cardiac autophagy may be an additional mechanism by which
Idit
is involved in the adaptive response to exercise. Our work suggests an ancient role of an Iditarod/Irisin/FNDC5 family of proteins in autophagy, exercise physiology, and cold adaptation, conserved throughout metazoan species.
Light-inducible T cell engagers trigger, tune, and shape the activation of primary T cells
Authors: Jaeger Morgane , Anastasio Amandine , Chamy Léa , Brustlein Sophie , Vincentelli Renaud , Durbesson Fabien , Gigan Julien , Thépaut Morgane , Char Rémy , Boussand Maud , Lechelon Mathias , Argüello Rafael J. , Marguet Didier , He Hai-Tao , Lasserre Rémi
Published: September 2023

To mount appropriate responses, T cells integrate complex sequences of receptor stimuli perceived during transient interactions with antigen-presenting cells. Although it has been hypothesized that the dynamics of these interactions influence the outcome of T cell activation, methodological limitations have hindered its formal demonstration. Here, we have engineered the Light-inducible T cell engager (LiTE) system, a recombinant optogenetics-based molecular tool targeting the T cell receptor (TCR). The LiTE system constitutes a reversible molecular switch displaying exquisite reactivity. As proof of concept, we dissect how specific temporal patterns of TCR stimulation shape T cell activation. We established that CD4
+
T cells respond to intermittent TCR stimulation more efficiently than their CD8
+
T cells counterparts and provide evidence that distinct sequences of TCR stimulation encode different cytokine programs. Finally, we show that the LiTE system could be exploited to create light-activated bispecific T cell engagers and manipulate tumor cell killing. Overall, the LiTE system provides opportunities to understand how T cells integrate TCR stimulations and to trigger T cell cytotoxicity with high spatiotemporal control.
Elliptic PDE learning is provably data-efficient
Authors: Boullé Nicolas , Halikias Diana , Townsend Alex
Published: September 2023

Partial differential equations (PDE) learning is an emerging field that combines physics and machine learning to recover unknown physical systems from experimental data. While deep learning models traditionally require copious amounts of training data, recent PDE learning techniques achieve spectacular results with limited data availability. Still, these results are empirical. Our work provides theoretical guarantees on the number of input–output training pairs required in PDE learning. Specifically, we exploit randomized numerical linear algebra and PDE theory to derive a provably data-efficient algorithm that recovers solution operators of three-dimensional uniformly elliptic PDEs from input–output data and achieves an exponential convergence rate of the error with respect to the size of the training dataset with an exceptionally high probability of success.
Combined prediction and design reveals the target recognition mechanism of an intrinsically disordered protein interaction domain
Authors: Hu Xiuhong , Xu Yang , Wang Chenchen , Liu Yufeng , Zhang Lu , Zhang Jiahai , Wang Wenning , Chen Quan , Liu Haiyan
Published: September 2023

An increasing number of protein interaction domains and their targets are being found to be intrinsically disordered proteins (IDPs). The corresponding target recognition mechanisms are mostly elusive because of challenges in performing detailed structural analysis of highly dynamic IDP-IDP complexes. Here, we show that by combining recently developed computational approaches with experiments, the structure of the complex between the intrinsically disordered C-terminal domain (CTD) of protein 4.1G and its target IDP region in NuMA can be dissected at high resolution. First, we carry out systematic mutational scanning using dihydrofolate reductase-based protein complementarity analysis to identify essential interaction regions and key residues. The results are found to be highly consistent with an α/β-type complex structure predicted by AlphaFold2 (AF2). We then design mutants based on the predicted structure using a deep learning protein sequence design method. The solved crystal structure of one mutant presents the same core structure as predicted by AF2. Further computational prediction and experimental assessment indicate that the well-defined core structure is conserved across complexes of 4.1G CTD with other potential targets. Thus, we reveal that an intrinsically disordered protein interaction domain uses an α/β-type structure module formed through synergistic folding to recognize broad IDP targets. Moreover, we show that computational prediction and experiment can be jointly applied to segregate true IDP regions from the core structural domains of IDP-IDP complexes and to uncover the structure-dependent mechanisms of some otherwise elusive IDP-IDP interactions.
Causal ALS genes impact the MHC class II antigen presentation pathway
Authors: Chi Binkai , Öztürk Muhammet M. , Paraggio Christina L. , Leonard Claudia E. , Sanita Maria E. , Dastpak Mahtab , O’Connell Jeremy D. , Coady Jordan A. , Zhang Jiuchun , Gygi Steven P. , Lopez-Gonzalez Rodrigo , Yin Shanye , Reed Robin
Published: September 2023

Mutations in RNA/DNA-binding proteins cause amyotrophic lateral sclerosis (ALS), but the underlying disease mechanisms remain unclear. Here, we report that a set of ALS-associated proteins, namely FUS, EWSR1, TAF15, and MATR3, impact the expression of genes encoding the major histocompatibility complex II (MHC II) antigen presentation pathway. Both subunits of the MHC II heterodimer, HLA-DR, are down-regulated in ALS gene knockouts/knockdown in HeLa and human microglial cells, due to loss of the MHC II transcription factor CIITA. Importantly, hematopoietic progenitor cells (HPCs) derived from human embryonic stem cells bearing the FUS
R495X
mutation and HPCs derived from C9ORF72 ALS patient induced pluripotent stem cells also exhibit disrupted MHC II expression. Given that HPCs give rise to numerous immune cells, our data raise the possibility that loss of the MHC II pathway results in global failure of the immune system to protect motor neurons from damage that leads to ALS.
Efficient C–N coupling in the direct synthesis of urea from CO
2
and N
2
by amorphous Sb
x
Bi
1-x
O
y
clusters
Authors: Chen Xiangyu , Lv Shuning , Kang Jianxin , Wang Zhongchang , Guo Tianqi , Wang Yu , Teobaldi Gilberto , Liu Li-Min , Guo Lin
Published: September 2023

Although direct generation of high-value complex molecules and feedstock by coupling of ubiquitous small molecules such as CO
2
and N
2
holds great appeal as a potential alternative to current fossil-fuel technologies, suitable scalable and efficient catalysts to this end are not currently available as yet to be designed and developed. To this end, here we prepare and characterize Sb
x
Bi
1-x
O
y
clusters for direct urea synthesis from CO
2
and N
2
via C–N coupling. The introduction of Sb in the amorphous BiO
x
clusters changes the adsorption geometry of CO
2
on the catalyst from O-connected to C-connected, creating the possibility for the formation of complex products such as urea. The modulated Bi(II) sites can effectively inject electrons into N
2
, promoting C–N coupling by advantageous modification of the symmetry for the frontier orbitals of CO
2
and N
2
involved in the rate-determining catalytic step. Compared with BiO
x
, Sb
x
Bi
1-x
O
y
clusters result in a lower reaction potential of only −0.3 V vs. RHE, an increased production yield of 307.97 μg h
−1
mg
−1
cat
, and a higher Faraday efficiency (10.9%), pointing to the present system as one of the best catalysts for urea synthesis in aqueous systems among those reported so far. Beyond the urea synthesis, the present results introduce and demonstrate unique strategies to modulate the electronic states of main group
p
-metals toward their use as effective catalysts for multistep electroreduction reactions requiring C–N coupling.
Photonic crystals built by time in ancient Roman glass
Authors: Guidetti Giulia , Zanini Roberta , Franceschin Giulia , Moglianetti Mauro , Kim Taehoon , Cohan Nathaniel , Chan Lisa , Treadgold John , Traviglia Arianna , Omenetto Fiorenzo G.
Published: September 2023

Ancient glass objects typically show distinctive effects of deterioration as a result of environmentally induced physicochemical transformations of their surface over time. Iridescence is one of the distinctive signatures of aging that is most commonly found on excavated glass. In this work, we present an ancient glass fragment that exhibits structural color through surface weathering resulting in iridescent patinas caused by silica reprecipitation in nanoscale lamellae. This archaeological artifact reveals an unusual hierarchically assembled photonic crystal with extremely ordered nanoscale domains, high spectral selectivity, and reflectivity (~90%), that collectively behaves like a gold mirror. Optical characterization paired with nanoscale elemental analysis further underscores the high quality of this structure providing a window into this sophisticated natural photonic crystal assembled by time.
Balancing social determinism vs. sound change
Authors: Burns Roslyn
Published: September 2023

This paper investigates the relationship between social and phonetic motivations for language change in Fang (Bantoid). While previous research has proposed that innovations in Fang arose due to social need and lack phonetic motivation (Mve et al. 2019; Good, Di Carlo & Tschonghongei 2020), I propose that there is a phonetic motivation and the social situation, at best, was a pathway for the innovation to gain wider adoption in the population. I provide comparative and language-internal evidence that the Fang innovations are driven by two interconnected processes, palatalization and spirantization, triggered by high vowels. These processes have been obscured synchronically in part due to the phonemic merger of *i > ə in some parts of the paradigm, thus making the alternations look phonetically unmotivated.
Yes(Rom.Da). Usages and functions in L2 proficiency examinations
Authors: Vasilescu Andra
Published: September 2023

The article analyses a Romanian corpus of intercultural dialogues recorded in natural settings during language proficiency examinations and discusses the usages of the frequently occurring wordyes(Rom.da). The framework is provided by the Mixed Game Model (Weigand 2009,2010,2017,2018, among others) intersected with the socio-cognitive approach to intercultural communication (Kecskes 2007,2008,2010,2013, among others). Beyond the analysis of a single lexical unit in a limited collection of texts, the author aims to demonstrate how a particular word of the lexicon becomes a culturally-socially-cognitively-discursively-rhetorically situated utterance that acquires specific functions when it is used by interlocutors who negotiate their communicative agendas to come not only to mutual understanding but also to achieve their convergent-divergent institutional purposes.
Military metaphors in the discourses of the pandemic in two post-Yugoslav states
Authors: Bogetić Ksenija
Published: September 2023

The present study contributes to the growing body of work on the pandemic-time use of the war metaphor in
public discourse, by focusing specifically on military metaphors in the media discourses of two post-Yugoslav, post-conflict
states. Using the approach of Critical Metaphor Analysis, the paper explores the discursive realizations of the war
metaphor in this context, with a particular focus on metaphor extension, metaphor entailments, and effects of earlier conflict
memory on discursive use of the metaphor. The results show how metaphor entailments may vary according to the kinds of war made
salient in discourse. Several forms of discursive use grounded in linking metaphorical and literal senses of war are identified,
as creating specific local meanings, which in the case area observed worked to relate representations of threat to dominant
instrumentalizations of historical memory and ongoing nationalist discourses. Beyond the local context, the findings are used to
discuss some aspects of pandemic-time war metaphor use important both for the theorizing of adversarial metaphors in
public discourse, and for more nuanced analyses of the discourses of crisis.
Enhanced Thermal Invisibility Effect in an Isotropic Thermal Cloak with Bulk Materials
Authors: Shan 单 Qingru 庆茹 , Shao 邵 Chunrui 春瑞 , Wang 王 Jun 军 , Xia 夏 Guodong 国栋
Published: September 2023

A thermal cloak is well known for hiding objects from thermal signature. A bilayer thermal cloak made from inner insulation layer and outer isotropic homogeneous layer could realize such thermal protection. However, its thermal protection performance can be suppressed for low-thermal-conductivity surrounding media. We propose a tri-layer thermal cloak model by adding a transition layer between the insulation layer and the outer layer. Numerical simulations and theoretical analysis show that, under the same geometry size and surrounding thermal conductivity, the performance of the thermal cloak can be significantly enhanced by introducing a transition layer with higher thermal conductivity and an outer-layer with lower thermal conductivity. The tri-layer cloak proposed provides a design guidance to realize better thermal protection using isotropic bulk materials.
Inverse Design and Experimental Verification of Metamaterials for Thermal Illusion Using Genetic Algorithms
Authors: He 何 Zonggang 宗堽 , Yuan 袁 Kun 坤 , Xiong 熊 Guohuan 国欢 , Wang 王 Jian 健
Published: September 2023

Thermal metamaterials offer a promising avenue for creating artificial materials with unconventional physical properties, such as thermal cloak, concentrator, rotator, and illusion. However, designs and fabrication of thermal metamaterials are of challenge due to the limitations of existing methods on anisotropic material properties. We propose an evolutionary framework for designing thermal metamaterials using genetic algorithm optimization. Our approach encodes unit cells with different thermal conductivities and performs global optimization using the evolution-inspired operators. We further fabricate the thermal functional cells using 3D printing and verify their thermal illusion functionality experimentally. Our study introduces a new design paradigm for advanced thermal metamaterials that can manipulate heat flows robustly and realize functional thermal metadevices without anisotropic thermal conductivity. Our approach can be easily applied to fabrications in various fields such as thermal management and thermal sensing.
Global Effects on Drift Wave Microturbulence in Tokamak Plasmas
Authors: Li 李 Hui 慧 , Li 李 Ji-Quan 继全 , Wang 王 Zheng-Xiong 正汹
Published: September 2023

Microturbulence excited by ion temperature gradient (ITG)-dominant and trapped electron mode (TEM)-dominant instabilities is investigated by employing an extended fluid code (ExFC) based on the so-called Landau fluid model, which includes the trapped electron dynamics. Firstly, the global effect is emphasized through direct comparison of ITG and TEM instability domains based on local and global simulations. The global effect makes differences in both linear instability and nonlinear transport, including the fluxes and the structure of zonal flow. The transitions among ITG, TEM, and ITG & TEM (ITG & TEM represents that ITG and TEM coexist with different wavelengths) instabilities/turbulence depend not only on the three key drive forces (R/L
n, R/L
Te, R/L
Ti) but also on their global (profile) effects. Secondly, a lot of electrostatic linear gyro-fluid simulations are concluded to obtain a distribution of the instability.
Printed and flexible organic and inorganic memristor devices for non-volatile memory applications
Authors: Jaafar Ayoub H , Gee Alex , Kemp N T
Published: September 2023

The electronics market is highly competitive and driven by consumers desire for the latest and most sophisticated devices at the lowest cost. In the last decade there has been increasing interest in printing electronic materials on lightweight and flexible substrates such as plastics and fabrics. This not only lowers fabrication and capital costs but also facilitates many new applications, such as flexible displays and wearable electronics. The printing of computer memory is also desirable since many of these applications require memory to store and process information. In addition, there is now an international effort to develop new types of computer memory that consume ultra-low levels of power. This is not only to lower energy usage worldwide, which is important for reducing CO2 emissions, but it also enables a longer period between the re-charging of devices such as mobile phones, music players and fitness bands. Memory that is non-volatile is an obvious choice since it does not consume power to retain information like conventional SRAM and DRAM. Memristors (or memory resistor) are a new type of memory that are intrinsically non-volatile in nature. Their simple two-terminal architecture, easy method of fabrication and low power consumption means they have received much attention from both the research community and industry. Devices with the lowest fabrication costs are made from organic or hybrid (organic–inorganic) composite materials because of the ability to use low-cost solution processing methods with the advantages of large area deposition under vacuum-free and room temperature ambient conditions. Memristors have excellent device properties, including a large resistance Off/On ratio (up to 5 orders of magnitude), fast switching speeds (less than 15 ns), long endurance (over 1012 cycles), long data storage retention time (∼10 years) and high scalability down to nanoscale dimensions. In this article we review progress in the field of printed and flexible memristor devices and discuss their potential across a wide range of applications.
Dynamic tunable narrow-band perfect absorber for fiber -optic communication band based on liquid crystal
Authors: Liu Mingliang , Li Boxun , Zeng Lili , Wei Yi , Wen Ruquan , Zhang Xingjiao , Deng Chaosheng
Published: September 2023

At present, most of the reported metasurface structure absorbers show that its working band cannot be regulated actively. In this study, a dynamic tunable narrow-band perfect absorption structure for fiber-optic communication band based on liquid crystal (LC) is proposed and studied. The structure is mainly composed of two effective tiers. The top tier gold array and the bottom tier reflective gold film, which are separated by a SiO2-LC dielectric medium interlayer to form a metal–dielectric–metal structure. Due to the unique optical properties of LCs, its index of refraction can be changed by adjusting the bias voltage and temperature, so as to adjust the resonance wavelength actively. The designed structure is analyzed by finite element method and the coupled mode theory is used to verify the analysis results. The designed structure has a 99.92% absorption effect in the most commonly used band of fiber-optic communication. Due to the symmetry of the absorber structure, the device is not sensitive to the polarization state of the excitation source. Moreover, the absorber exhibits an unusual dependence on the incident angle, which can be attributed to the anisotropy of the LC. Based on the dependence of incident angle, a plasma optical switch with large ON/OFF ratio (η) of 27.395 dB and nearly flawless modulation depth of 99.818% can be realized. It is believed that this structure can provide a method for the dynamic control of near infrared electromagnetic waves, and to be applied in electromagnetic energy absorption, filtering and plasma optical switch system.