bluuebunny/crossref_metadata_2025 huggingface dataset:
Promote electroreduction of CO
2
via catalyst valence state manipulation by surface-capping ligand
Authors: Zhao Yilin , Liu Xiaoqing , Chen Jingyi , Chen Junmei , Chen Jiayi , Fan Lei , Yang Haozhou , Xi Shibo , Shen Lei , Wang Lei
Published: May 2023

Electrochemical CO
2
reduction provides a potential means for synthesizing value-added chemicals over the near equilibrium potential regime, i.e., formate production on Pd-based catalysts. However, the activity of Pd catalysts has been largely plagued by the potential-depended deactivation pathways (e.g.,

α

-PdH to

β

-PdH phase transition, CO poisoning), limiting the formate production to a narrow potential window of 0 V to −0.25 V vs. reversible hydrogen electrode (RHE). Herein, we discovered that the Pd surface capped with polyvinylpyrrolidone (PVP) ligand exhibits effective resistance to the potential-depended deactivations and can catalyze formate production at a much extended potential window (beyond –0.7 V vs. RHE) with significantly improved activity (~14-times enhancement at −0.4 V vs. RHE) compared to that of the pristine Pd surface. Combined results from physical and electrochemical characterizations, kinetic analysis, and first-principle simulations suggest that the PVP capping ligand can effectively stabilize the high-valence-state Pd species (Pd
δ+
) resulted from the catalyst synthesis and pretreatments, and these Pd
δ+
 species are responsible for the inhibited phase transition from

α

-PdH to

β

-PdH, and the suppression of CO and H
2
formation. The present study confers a desired catalyst design principle, introducing positive charges into Pd-based electrocatalyst to enable efficient and stable CO
2
to formate conversion.
Primary cilia TRP channel regulates hippocampal excitability
Authors: Vien Thuy N. , Ta My C. , Kimura Louise F. , Onay Tuncer , DeCaen Paul G.
Published: May 2023

Polycystins (PKD2, PKD2L1, and PKD2L2) are members of the transient receptor potential family, which form ciliary ion channels. Most notably, PKD2 dysregulation in the kidney nephron cilia is associated with polycystic kidney disease, but the function of PKD2L1 in neurons is undefined. In this report, we develop animal models to track the expression and subcellular localization of PKD2L1 in the brain. We discover that PKD2L1 localizes and functions as a Ca
2+
channel in the primary cilia of hippocampal neurons that apically radiate from the soma. Loss of PKD2L1 expression ablates primary ciliary maturation and attenuates neuronal high-frequency excitability, which precipitates seizure susceptibility and autism spectrum disorder–like behavior in mice. The disproportionate impairment of interneuron excitability suggests that circuit disinhibition underlies the neurophenotypic features of these mice. Our results identify PKD2L1 channels as regulators of hippocampal excitability and the neuronal primary cilia as organelle mediators of brain electrical signaling.
Mechanosensitive stem cell fate choice is instructed by dynamic fluctuations in activation of Rho GTPases
Authors: Sampayo Rocío G. , Sakamoto Mason , Wang Madeline , Kumar Sanjay , Schaffer David V.
Published: May 2023

During the intricate process by which cells give rise to tissues, embryonic and adult stem cells are exposed to diverse mechanical signals from the extracellular matrix (ECM) that influence their fate. Cells can sense these cues in part through dynamic generation of protrusions, modulated and controlled by cyclic activation of Rho GTPases. However, it remains unclear how extracellular mechanical signals regulate Rho GTPase activation dynamics and how such rapid, transient activation dynamics are integrated to yield long-term, irreversible cell fate decisions. Here, we report that ECM stiffness cues alter not only the magnitude but also the temporal frequency of RhoA and Cdc42 activation in adult neural stem cells (NSCs). Using optogenetics to control the frequency of RhoA and Cdc42 activation, we further demonstrate that these dynamics are functionally significant, where high- vs. low-frequency activation of RhoA and Cdc42 drives astrocytic vs. neuronal differentiation, respectively. In addition, high-frequency Rho GTPase activation induces sustained phosphorylation of the TGFβ pathway effector SMAD1, which in turn drives the astrocytic differentiation. By contrast, under low-frequency Rho GTPase stimulation, cells fail to accumulate SMAD1 phosphorylation and instead undergo neurogenesis. Our findings reveal the temporal patterning of Rho GTPase signaling and the resulting accumulation of an SMAD1 signal as a critical mechanism through which ECM stiffness cues regulate NSC fate.
Modulation of deep neural circuits with sonogenetics
Authors: Xian Quanxiang , Qiu Zhihai , Murugappan Suresh , Kala Shashwati , Wong Kin Fung , Li Danni , Li Guofeng , Jiang Yizhou , Wu Yong , Su Min , Hou Xuandi , Zhu Jiejun , Guo Jinghui , Qiu Weibao , Sun Lei
Published: May 2023

Noninvasive control of neuronal activity in the deep brain can be illuminating for probing brain function and treating dysfunctions. Here, we present a sonogenetic approach for controlling distinct mouse behavior with circuit specificity and subsecond temporal resolution. Targeted neurons in subcortical regions were made to express a mutant large conductance mechanosensitive ion channel (MscL-G22S), enabling ultrasound to trigger activity in MscL-expressing neurons in the dorsal striatum and increase locomotion in freely moving mice. Ultrasound stimulation of MscL-expressing neurons in the ventral tegmental area could activate the mesolimbic pathway to trigger dopamine release in the nucleus accumbens and modulate appetitive conditioning. Moreover, sonogenetic stimulation of the subthalamic nuclei of Parkinson’s disease model mice improved their motor coordination and mobile time. Neuronal responses to ultrasound pulse trains were rapid, reversible, and repeatable. We also confirmed that the MscL-G22S mutant is more effective to sensitize neurons to ultrasound compared to the wild-type MscL. Altogether, we lay out a sonogenetic approach which can selectively manipulate targeted cells to activate defined neural pathways, affect specific behaviors, and relieve symptoms of neurodegenerative disease.
MicroRNA-205 promotes hair regeneration by modulating mechanical properties of hair follicle stem cells
Authors: Wang Jingjing , Fu Yuheng , Huang Wenmao , Biswas Ritusree , Banerjee Avinanda , Broussard Joshua A. , Zhao Zhihai , Wang Dongmei , Bjerke Glen , Raghavan Srikala , Yan Jie , Green Kathleen J. , Yi Rui
Published: May 2023

Stiffness and actomyosin contractility are intrinsic mechanical properties of animal cells required for the shaping of tissues. However, whether tissue stem cells (SCs) and progenitors located within SC niche have different mechanical properties that modulate their size and function remains unclear. Here, we show that hair follicle SCs in the bulge are stiff with high actomyosin contractility and resistant to size change, whereas hair germ (HG) progenitors are soft and periodically enlarge and contract during quiescence. During activation of hair follicle growth, HGs reduce contraction and more frequently enlarge, a process that is associated with weakening of the actomyosin network, nuclear YAP accumulation, and cell cycle reentry. Induction of
miR-205
, a novel regulator of the actomyosin cytoskeleton, reduces actomyosin contractility and activates hair regeneration in young and old mice. This study reveals the control of tissue SC size and activities by spatiotemporally compartmentalized mechanical properties and demonstrates the possibility to stimulate tissue regeneration by fine-tuning cell mechanics.
LEAFY and APETALA1 down-regulate ZINC FINGER PROTEIN 1 and 8 to release their repression on class B and C floral homeotic genes
Authors: Hu Tieqiang , Li Xiaohui , Du Liren , Manuela Darren , Xu Mingli
Published: May 2023

Organ initiation from the shoot apical meristem first gives rise to leaves during vegetative development and then flowers during reproductive development.
LEAFY
(
LFY
) is activated after floral induction and together with other factors promotes the floral program. LFY functions redundantly with APETALA1 (AP1) to activate the class B genes
APETALA3
(
AP3
) and
PISTILLATA
(
PI
), the class C gene
AGAMOUS
(
AG
), and the class E gene
SEPALLATA3
, which leads to the specification of stamens and carpels, the reproductive organs of flowers. Molecular and genetic networks that control the activation of
AP3,
PI,
and
AG
in flowers have been well studied; however, much less is known about how these genes are repressed in leaves and how their repression is lifted in flowers. Here, we showed that two genes encoding
Arabidopsis
C2H2 ZINC FINGER PROTEIN (ZFP) transcription factors, ZP1 and ZFP8, act redundantly to directly repress
AP3,
PI,
and
AG
in leaves. After
LFY
and
AP1
are activated in floral meristems, they down-regulate
ZP1
and
ZFP8
directly to lift the repression on
AP3,
PI,
and
AG
. Our results reveal a mechanism for how floral homeotic genes are repressed and derepressed before and after floral induction.
Inferring the differences in incubation-period and generation-interval distributions of the Delta and Omicron variants of SARS-CoV-2
Authors: Park Sang Woo , Sun Kaiyuan , Abbott Sam , Sender Ron , Bar-on Yinon M. , Weitz Joshua S. , Funk Sebastian , Grenfell Bryan T. , Backer Jantien A. , Wallinga Jacco , Viboud Cecile , Dushoff Jonathan
Published: May 2023

Estimating the differences in the incubation-period, serial-interval, and generation-interval distributions of SARS-CoV-2 variants is critical to understanding their transmission. However, the impact of epidemic dynamics is often neglected in estimating the timing of infection—for example, when an epidemic is growing exponentially, a cohort of infected individuals who developed symptoms at the same time are more likely to have been infected recently. Here, we reanalyze incubation-period and serial-interval data describing transmissions of the Delta and Omicron variants from the Netherlands at the end of December 2021. Previous analysis of the same dataset reported shorter mean observed incubation period (3.2 d vs. 4.4 d) and serial interval (3.5 d vs. 4.1 d) for the Omicron variant, but the number of infections caused by the Delta variant decreased during this period as the number of Omicron infections increased. When we account for growth-rate differences of two variants during the study period, we estimate similar mean incubation periods (3.8 to 4.5 d) for both variants but a shorter mean generation interval for the Omicron variant (3.0 d; 95% CI: 2.7 to 3.2 d) than for the Delta variant (3.8 d; 95% CI: 3.7 to 4.0 d). The differences in estimated generation intervals may be driven by the “network effect”—higher effective transmissibility of the Omicron variant can cause faster susceptible depletion among contact networks, which in turn prevents late transmission (therefore shortening realized generation intervals). Using up-to-date generation-interval distributions is critical to accurately estimating the reproduction advantage of the Omicron variant.
Structural insights into the transcription activation mechanism of the global regulator GlnR from actinobacteria
Authors: Shi Jing , Feng Zhenzhen , Xu Juncao , Li Fangfang , Zhang Yuqiong , Wen Aijia , Wang Fulin , Song Qian , Wang Lu , Cui Hong , Tong Shujuan , Chen Peiying , Zhu Yejin , Zhao Guoping , Wang Shuang , Feng Yu , Lin Wei
Published: May 2023

In actinobacteria, an OmpR/PhoB subfamily protein called GlnR acts as an orphan response regulator and globally coordinates the expression of genes responsible for nitrogen, carbon, and phosphate metabolism in actinobacteria. Although many researchers have attempted to elucidate the mechanisms of GlnR-dependent transcription activation, progress is impeded by lacking of an overall structure of GlnR-dependent transcription activation complex (GlnR-TAC). Here, we report a co-crystal structure of the C-terminal DNA-binding domain of GlnR (GlnR_DBD) in complex with its regulatory
cis
-element DNA and a cryo-EM structure of GlnR-TAC which comprises
Mycobacterium tuberculosis
RNA polymerase, GlnR, and a promoter containing four well-characterized conserved GlnR binding sites. These structures illustrate how four GlnR protomers coordinate to engage promoter DNA in a head-to-tail manner, with four N-terminal receiver domains of GlnR (GlnR-RECs) bridging GlnR_DBDs and the RNAP core enzyme. Structural analysis also unravels that GlnR-TAC is stabilized by complex protein–protein interactions between GlnR and the conserved β flap, σ
A
R4, αCTD, and αNTD domains of RNAP, which are further confirmed by our biochemical assays. Taken together, these results reveal a global transcription activation mechanism for the master regulator GlnR and other OmpR/PhoB subfamily proteins and present a unique mode of bacterial transcription regulation.
Activation of skeletal muscle is controlled by a dual-filament mechano-sensing mechanism
Authors: Brunello Elisabetta , Marcucci Lorenzo , Irving Malcolm , Fusi Luca
Published: May 2023

Contraction of skeletal muscle is triggered by a transient rise in intracellular calcium concentration leading to a structural change in the actin-containing thin filaments that allows binding of myosin motors from the thick filaments. Most myosin motors are unavailable for actin binding in resting muscle because they are folded back against the thick filament backbone. Release of the folded motors is triggered by thick filament stress, implying a positive feedback loop in the thick filaments. However, it was unclear how thin and thick filament activation mechanisms are coordinated, partly because most previous studies of the thin filament regulation were conducted at low temperatures where the thick filament mechanisms are inhibited. Here, we use probes on both troponin in the thin filaments and myosin in the thick filaments to monitor the activation states of both filaments in near-physiological conditions. We characterize those activation states both in the steady state, using conventional titrations with calcium buffers, and during activation on the physiological timescale, using calcium jumps produced by photolysis of caged calcium. The results reveal three activation states of the thin filament in the intact filament lattice of a muscle cell that are analogous to those proposed previously from studies on isolated proteins. We characterize the rates of the transitions between these states in relation to thick filament mechano-sensing and show how thin- and thick-filament-based mechanisms are coupled by two positive feedback loops that switch on both filaments to achieve rapid cooperative activation of skeletal muscle.
Structure–function study of a Ca
2+
-independent metacaspase involved in lateral root emergence
Authors: Stael Simon , Sabljić Igor , Audenaert Dominique , Andersson Thilde , Tsiatsiani Liana , Kumpf Robert P. , Vidal-Albalat Andreu , Lindgren Cecilia , Vercammen Dominique , Jacques Silke , Nguyen Long , Njo Maria , Fernández-Fernández Álvaro D. , Beunens Tine , Timmerman Evy , Gevaert Kris , Van Montagu Marc , Ståhlberg Jerry , Bozhkov Peter V. , Linusson Anna , Beeckman Tom , Van Breusegem Frank
Published: May 2023

Metacaspases are part of an evolutionarily broad family of multifunctional cysteine proteases, involved in disease and normal development. As the structure–function relationship of metacaspases remains poorly understood, we solved the X-ray crystal structure of an
Arabidopsis thaliana
type II metacaspase (AtMCA-IIf) belonging to a particular subgroup not requiring calcium ions for activation. To study metacaspase activity in plants, we developed an in vitro chemical screen to identify small molecule metacaspase inhibitors and found several hits with a minimal thioxodihydropyrimidine-dione structure, of which some are specific AtMCA-IIf inhibitors. We provide mechanistic insight into the basis of inhibition by the TDP-containing compounds through molecular docking onto the AtMCA-IIf crystal structure. Finally, a TDP-containing compound (TDP6) effectively hampered lateral root emergence in vivo, probably through inhibition of metacaspases specifically expressed in the endodermal cells overlying developing lateral root primordia. In the future, the small compound inhibitors and crystal structure of AtMCA-IIf can be used to study metacaspases in other species, such as important human pathogens, including those causing neglected diseases.
Combined hydrometallurgical route for recovery of metals from spent LIB using hydrochloric acid and phosphonium ionic liquid
Authors: Mohanty Archita , Marandi Barsha , Devi Niharbala
Published: May 2023

This research explored the significance of Cyphos IL 101 in recovering metal values from waste LiMn2O4 batteries. Several leaching parameters were investigated to recover metals from the leach liquor of the battery material. The maximum leaching efficiency of Li (100%) and Mn (99.6%) was attained with 3.0 mol/L hydrochloric acid, 30°C, S/L ratio of 10 g/L, and 60 min leaching duration. The leaching process was diffusion-controlled. At pH 5.5, the separation of manganese and lithium exhibited excellent selectivity towards manganese over lithium using 0.1 mol/L Cyphos IL 101. 99.6% manganese extraction and negligible lithium extraction were obtained with two stages of counter-current extraction at A/O 1:1 predicted by the McCabe-Thiele plot. Using 0.1 mol/L hydrochloric acid, a stripping efficiency of 99.4% was attained for manganese.
Autoinhibitory mechanism controls binding of centrosomin motif 1 to γ-tubulin ring complex
Authors: Yang Shaozhong , Au Franco K.C. , Li Gefei , Lin Jianwei , Li Xiang David , Qi Robert Z.
Published: May 2023

The γ-tubulin ring complex (γTuRC) is the principal nucleator of cellular microtubules, and the microtubule-nucleating activity of the complex is stimulated by binding to the γTuRC-mediated nucleation activator (γTuNA) motif. The γTuNA is part of the centrosomin motif 1 (CM1), which is widely found in γTuRC stimulators, including CDK5RAP2. Here, we show that a conserved segment within CM1 binds to the γTuNA and blocks its association with γTuRCs; therefore, we refer to this segment as the γTuNA inhibitor (γTuNA-In). Mutational disruption of the interaction between the γTuNA and the γTuNA-In results in a loss of autoinhibition, which consequently augments microtubule nucleation on centrosomes and the Golgi complex, the two major microtubule-organizing centers. This also causes centrosome repositioning, leads to defects in Golgi assembly and organization, and affects cell polarization. Remarkably, phosphorylation of the γTuNA-In, probably by Nek2, counteracts the autoinhibition by disrupting the γTuNA‒γTuNA-In interaction. Together, our data reveal an on-site mechanism for controlling γTuNA function.
Molecular rearrangements in S6 during slow inactivation in Shaker-IR potassium channels
Authors: Szanto Tibor G. , Papp Ferenc , Zakany Florina , Varga Zoltan , Deutsch Carol , Panyi Gyorgy
Published: May 2023

Voltage-gated K+ channels have distinct gates that regulate ion flux: the activation gate (A-gate) formed by the bundle crossing of the S6 transmembrane helices and the slow inactivation gate in the selectivity filter. These two gates are bidirectionally coupled. If coupling involves the rearrangement of the S6 transmembrane segment, then we predict state-dependent changes in the accessibility of S6 residues from the water-filled cavity of the channel with gating. To test this, we engineered cysteines, one at a time, at S6 positions A471, L472, and P473 in a T449A Shaker-IR background and determined the accessibility of these cysteines to cysteine-modifying reagents MTSET and MTSEA applied to the cytosolic surface of inside-out patches. We found that neither reagent modified either of the cysteines in the closed or the open state of the channels. On the contrary, A471C and P473C, but not L472C, were modified by MTSEA, but not by MTSET, if applied to inactivated channels with open A-gate (OI state). Our results, combined with earlier studies reporting reduced accessibility of residues I470C and V474C in the inactivated state, strongly suggest that the coupling between the A-gate and the slow inactivation gate is mediated by rearrangements in the S6 segment. The S6 rearrangements are consistent with a rigid rod-like rotation of S6 around its longitudinal axis upon inactivation. S6 rotation and changes in its environment are concomitant events in slow inactivation of Shaker KV channels.
The Big Bang could be anisotropic. The case of Bianchi I model
Authors: Parnovsky S L
Published: May 2023

We consider an evolution of anisotropic cosmological model on the example of the Bianchi type I homogeneous Universe. It is filled by the mixture of matter and dark energy with an arbitrary barotropic equation of state (EoS). The general solution for this case is found and analyzed. A complete list of possible future singularities for this model is given. Some new solution were obtained for a particular EoSs, e.g. for the Bianchi type I ΛCDM homogeneous model. It is shown that all special cases corresponding to different EoSs have common properties, provided that now or at another moment of time the Universe is expanding, and the density of the mixture is positive. Then the evolution always begins with an anisotropic ‘Big Bang’ which happened a finite time ago. After that the Universe is constantly expanding and in all cases, with rare exceptions, becomes more isotropic. A particularly strong isotropization is associated with the epoch of inflation. After its completion, the expansion of the Universe becomes almost isotropic, and this case cannot be distinguished from isotropic by astronomical observations. This fact allows us to consider an anisotropic cosmological model as a possible candidate for the description of the observed Universe despite the isotropic pattern of expansion.
Enhanced broadband light absorption of ultrathin PtSe2 in metal–insulator–metal structure
Authors: He Junbo , Chen Cheng , Liu Weiming , Zhu Xudan , Zheng Yuxiang , Wang Songyou , Chen Liangyao , Zhang Rongjun
Published: May 2023

The enhancement of light absorption in an ultrathin two-dimensional material is critical for its optoelectronic and photonic applications. In this work, we investigated the enhanced light absorption of layered PtSe2 by engineering the optical impedance and the attenuation of the PtSe2-based metal–insulator–metal (MIM) absorber. For a monolayer PtSe2-based MIM absorber, the undesirable impedance mismatch can be compensated for using the top patterned metal array in the MIM structure to achieve near-perfect absorption (99.95%), and the absorption of monolayer PtSe2 is enhanced by 8.6 times in the visible spectra. For a few-layer PtSe2 MIM absorber, the self-impedance of the PtSe2 layer becomes an important factor in modulating the optical absorption and the PtSe2-based absorbers show excellent features with broadband absorption, insensitive to the incident angle and polarization. Our results improve the viability of the PtSe2-based optoelectronic and photonic devices and shed light on the design of absorbers with hybrid 2D materials.
Revisiting the stable structures of gold clusters: Au
n
(n = 16–25) by artificial neural network potential
Authors: Guo Yibo , Wu Xue , Fu Jie
Published: May 2023

Identifying the stable structures of gold (Au) clusters is a huge challenge in cluster science. In this work, we have searched the ground-state structures of neutral Au
n
(n = 16–25) clusters using the potential of an artificial neural network (ANN) trained with density functional theory (DFT) data. Compared with the DFT data, the root mean square error of binding energy predicted by the ANN potential is about 8.66 meV/atom. Applying the ANN potential to search the ground-state structures by comprehensive genetic algorithm, we have found several new candidates of Au18, Au22, and Au23, which have not been previously reported. Au18 has a hollow cage structure, whereas Au22 and Au23 are flat cage structures. From the electronic analysis, we elucidate the stability mechanism of the newly found structures that are associated with the electronic shell closure of superatomic orbitals. Additonally, we also clarified how to clean a database to train an efficient ANN potential in detail. Overall, this work proves that applying machine learning to the description of atomic interactions can accelerate the search of ground-state structures of clusters and help to find new candidates for stable cluster structures.
Prediction of OES intensity ratios based on coating unit data in HPPMS processes by ANN
Authors: Bobzin K , Kalscheuer C , Möbius M P , Schulze C
Published: May 2023

High power pulse magnetron sputtering (HPPMS) processes are characterized by high peak powers and peak voltages. This results in a high fraction of ionized metal ions within the coating plasma. In order to analyze the correlations between parameters of the coating unit and the intensities of the excited and ionized plasma species, optical emission spectroscopy (OES) can be used. In those experiments, several process parameters are varied in a single coating process. Currently, the prediction of plasma parameters based on coating unit data follows deterministic models which cannot describe the complexity in total. Therefore, not all correlations can be fully understood. Artificial neural networks (ANN) can be used to identify correlations between process parameters and plasma species. This enables prediction of OES data based on data of the coating machine. In the present study different coating processes containing the elements Al, Cr, Ti, N and O were investigated. Current and voltages of the cathodes, substrate bias, chamber pressure, gas flows and the target compositions were used as input parameter of the ANN. Time resolved OES data of metal and gas species were used as output data. To determine the most appropriate training algorithm for the current predictions, multiple algorithms were employed. A good prediction accuracy of OES intensity ratios based on coating unit data for industrial scale coating processes for TiAlN was obtained. For CrAlON the prediction of the intensity ratios of the gas species showed good results. Nowadays a high amount of coating machine parameter variations in physical vapor deposition processes is needed in order to achieve tailored coating parameters. By using plasma diagnostics, such as OES, cost intensive coating deposition processes can be reduced significantly. A further shortening of process development time is possible by using ANN, since plasma compositions can be determined based on coating unit data.
Excitonic Floquet states in quantum wire
Authors: Chwiej Tomasz , Dziembaj Grzegorz
Published: May 2023

We use Floquet theory to study the effects of laser light coupling to an electron–hole pair confined in a quantum wire. Fast oscillating electric field directed along the wire continuously displaces spatially the electron and hole in opposite directions, that influences on effective time-averaged electrostatic interaction by shallowing its minimum. Renormalization of binding energy leaves distinctive stamp in Floquet energy spectra because both the ponderomotive and confining energies may be neglected in considered perturbative regime. Due to renormalization of binding energy the blueshifted dressed exciton’s energy states form crossings and avoided crossings in energy spectra while their oscillator strengths are gradually reduced for increasing laser intensity, these features are strongly dependent on spatial sizes of wire. Discussed properties of Floquet exciton confined in QWr could potentially be used to build the fast terahertz optical bright-dark state switcher or to realize Floquet-Landau-Zener transition.
Traceable determination of the size of nanoparticles up to 500 nm by scanning electron microscopy in transmission mode based on simulation
Authors: Hüser Dorothee , Bergmann Detlef , Klein Tobias
Published: May 2023

The size measurement of nanoparticles contributes to the understanding of their properties and, thus, to the assessment of the risks they pose to health and the environment. For such measurements to be comparable and legally recognized, they must be traceable to the SI unit meter. Recently, interest in traceable measurements of polystyrene particles with sizes up to 500 nm has aroused, e.g. in the aerosol community. To meet this demand, we adapted an established method to traceably measure nanoparticles with high precision in the transmission mode of a scanning electron microscope (STEM-in-SEM or TSEM). Since this method was geared towards smaller particles, we adapted it at two points: New simulations with the program Geant4SEM allow a more accurate modelling, especially of the inelastical scattering processes. In addition, the image evaluation procedure was revised to account for the non-linear signal response at the particle boundary. The measured values obtained in this manner show good agreement with the values of two international intercomparisons.
Monolithic light concentration by core–shell TiO2 nanostructures templated by monodisperse polymer colloidal monolayers
Authors: Cherry Rachel , Muhanga Joseph Joel , Mehrabi Hamed , Conlin Samuel K , Coridan Robert H
Published: May 2023

Nanostructured dielectric overlayers can be used to increase light absorption in nanometer-thin films used for various optoelectronic applications. Here, the self-assembly of a close-packed monolayer of polystyrene nanospheres is used to template a core–shell polystyrene-TiO2 light-concentrating monolithic structure. This is enabled by the growth of TiO2 at temperatures below the polystyrene glass-transition temperature via atomic layer deposition. The result is a monolithic, tailorable nanostructured overlayer fabricated by simple chemical methods. The design of this monolith can be tailored to generate significant absorption increases in thin film light absorbers. Finite-difference, time domain simulations are used to explore the design polystyrene-TiO2 core–shell monoliths that maximize light absorption in a 40 nm GaAs-on-Si substrate as a model for a photoconductive antenna THz emitter. An optimized core–shell monolith structure generated a greater than 60-fold increase of light absorption at a single wavelength in the GaAs layer of the simulated model device.
Superconducting properties of pt-type and bct-type YRh4B4
Authors: Kurata K , Muranaka T
Published: May 2023

YRh4B4, which exhibits high-

T

c

superconductivity in the RRh4B4 system, has two types of crystal structures, CeCo4B4 type (pt-type) and LuRu4B4 type (bct-type). Both types of structure have similar

T

c

(pt-type;

T

c

= 10.6 K, bct-type;

T

c

= 9.8 K), but the

μ
0

H

c
2

of both compounds is very different, pt-type;

μ
0

H

c
2

= 2.50 T and bct-type;

μ
0

H

c
2

= 9.85 T. From our results, one can see that the difference in

T

c

between pt-YRh4B4 and bct-YRh4B4 is mainly caused from the difference of the density of state at Fermi energy. The high-

T

c

in pt-YRh4B4 is derived from the high Debye temperature caused by vibrations of boron. In contrast, in bct-YRh4B4 it is caused by a stronger electron–phonon coupling than in pt-YRh4B4. Regarding the symmetry of superconductivity, it is suggested that pt-YRh4B4 is a clean limit superconductor and has basically a fully gapped superconducting gap, but is slightly anisotropic from the results of

C

el

∝

exp

(
−
Δ

/

k

B

T

) below

T

c

and

Δ
γ
(
H
)
∝

H

0.65

. However, bct-YRh4B4 is a dirty limit superconductor and has an anisotropic superconducting gap from the results of

C

el

∝

T

3

below

T

c

and

Δ
γ
(
H
)
∝
H

.
Influence of surrounding vortices on critical current of a Nb/Al-AlO
x
/Nb Josephson junction
Authors: Pan Yinping , Zhang Denghui , Yang Ruoting , Wu Guangting , Zeng Junwen , Peng Wei , Wang Zhen , Ren Jie , Chen Lei
Published: May 2023

Resistively shunted Nb/Al-AlO
x
/Nb Josephson junctions have been widely used in large-scale superconducting electronics such as the single-flux quantum circuit. The critical current primarily determines the working margin of the circuit. The distribution of vortices in the niobium film around superconducting devices is also commonly suspected to degrade the performance of devices. Unfortunately, most studies on Nb/Al-AlO
x
/Nb Josephson junctions only present electric transport measurements. Using a magnetic force microscope, we observed the static distribution of the vortices around the junction after sweeping the current–voltage curves of the junction in-situ. The measurements showed that the distribution density of vortices affected the critical current of the junction. Furthermore, we observed an aggregation of vortices arising from the Joule heat generated by the shunt resistor. This caused an irreversible decrease in the junction’s critical current.
Multi-pico-Coulomb and multi-GeV electron beam generation from LWFA with a cm scale gas cell
Authors: Ghotra Harjit Singh
Published: May 2023

Analytical calculations are made for the scaling and design parameters for the generation of a multi-pico Coulomb and multi-GeV electron beam from a laser Wakefield acceleration (LWFA). The numerical values are optimized for electron acceleration from a cm-scale gas cell and self-guided laser plasma in the bubble domain, where the low-density plasma serves as an accelerating medium. A graphical analysis of the matched parameters is presented for 1–10 GeV electron beam energy gain, where the laser pulse is powered between 30 ∼ 700 TW with delivery capabilities of 1–100 J pulse energy, 25–150 fs pulse duration, and 15–95 μm spot size operating with 1018–19 W cm−2 laser intensity at a plasma density ∼1017 cm−3. The result shows the generation of multi-pico-Coulomb and multi-GeV electron beams. These parameters will be helpful for the future LWFA related experiments using cm scale gas cells in the bubble regime.
Extended phase space thermodynamics of black hole with non-linear electrodynamic field
Authors: Abbas G. , Ali R. H.
Published: May 2023

This paper deals with the thermodynamical properties of the black hole formulated in Einstein's theory of relativity associated with a nonlinear electromagnetic field. The transition of the black hole is analyzed using the mass, electric charge, coupling constant, and cosmological constant. We examine the thermodynamical aspects of exact black hole solutions to compute the black hole mass, temperature, entropy, Gibbs free energy, specific heat, and critical exponents in the phase space. Further, we study the stability of the black hole solution using the specific heat and Gibbs free energy. We examine the first and second phase changes and show a P-V criticality, which is similar to the van der Waals phase change. We also examine the equation of the state and the critical exponents.
Towards the use of SDD as an absolute detector for high-energy neutron measurements
Authors: Perelli Cippo E. , Cazzaniga C. , Paoletti M. , Colombi S. , Caruggi F. , Petruzzo M. , Rigamonti D. , Frost C. , Rebai M.
Published: May 2023

As of today, the standard method employed in tokamaks for the absolute measurement of the neutron flux (thus of the nuclear fusion power) is based on activation foils, being the most robust and unbiased technique for the absolute determination of neutron fluence. However, this technique is not able to provide real-time data useful for the control of future fusion plants like DEMO. In this paper, we present some preliminary results about the R&D activity aimed at developing the Single-crystal Diamond Detectors (SDD) used for fast neutron measurements into an absolute neutron flux monitor. Tests have been conducted at the new NILE neutron source of the Rutherford-Appleton Laboratory, a facility with compact neutron generators with a maximum yield of 109 n/s and 1010 n/s for 2.5 MeV and 14 MeV neutrons, respectively. A series of neutron spectra and flux measurements have been taken with different SDD and associated DAQ. Comparisons with standard activation foils (and namely Fe, Zr, Al and Nb foils for 14 MeV neutrons and In for 2.5 MeV neutrons) and with other reference detectors are presented and discussed. Also discussed is the stability of the SDD over time when employed at high neutron rates in realistic neutron environment, and the effects of neutron irradiation on both the counting rate and detector resolution.
Design of an X-ray diagnosis system with TIADC
Authors: Ye H.Q. , Jin G. , Chen L. , Hu Q. , Sun Y. , Chen B.L.
Published: May 2023

X-ray diagnosis is a crucial aspect of nuclear experiments, as many fields in physical research require X-ray analysis. The X-ray diode (XRD) detector is commonly used in X-ray detection due to its short response time, necessitating a high-speed readout circuit. In this paper, we present the design of an X-ray diagnosis system with readout electronics utilizing time-interleaved analog-to-digital converters (TIADC). One of the challenging problems in TIADC is the mismatch problem between channels, which severely reduces the system's performance. We propose a fast calibration method for adjusting the mismatch, significantly improving the acquisition system's performance. We have implemented an adapted module to perform the calibration in real-time. In performance tests, the proposed method is shown to be as effective as other methods, and the electronic performance of the system meets the diagnosis requirements. The X-ray signals acquired by this system exhibit high quality in the inertial confinement fusion (ICF) of the SG-III laser facility.
A feasibility study of multi-electrode high-purity germanium detector for 76Ge neutrinoless double beta decay searching
Authors: Yang Jingzhe , Tian Yang , Dai Wenhan , Yang Mingxin , Jiang Lin , Wen Jingjun , Xue Tao , Zeng Ming , Li Yulan , Zeng Zhi
Published: May 2023

Experiments to search for neutrinoless double-beta
(0νββ) decay of 76Ge using a high-purity
germanium (HPGe) detector rely heavily on background suppression
technologies to enhance their sensitivities. In this work, we
proposed a pulse-shape analysis method based on a neural network
(NN) and a light gradient boosting machine (lightGBM; LGB) to
discriminate single-electron (background) and double-electrons
(0νββ signal) events in a multi-electrode HPGe
detector. In this paper, we describe a multi-electrode HPGe detector
system, a data-processing system, and pulse-shape simulation
procedures. We built a fully connected (FC) neural network and an
LGB model to classify the single- and double-electron events. The FC
network is trained with simulated single- and
double-electron-induced pulses and tested in an independent dataset
generated by the pulse-shape simulation. The discrimination
efficiency of the FC neural network in the test set for the
0νββ double-electron events signal was 77.4%, the
precision was 57.7%, and the training time was 430 min. The
discrimination efficiency of LGB model was 73.1%, the precision was
64.0%, and the training time was 1.5 min. This study demonstrated
that it is feasible to realize single- and double-electron
discrimination on multi-electrode HPGe detectors using an FC neural
network and LGB model. These results can be used as a reference for
future 76Ge 0νββ experiments.
Orographic mechanical and surface thermal effects of the Tibetan–Iranian Plateau on extratropical intraseasonal waves in boreal summer: numerical experiments
Authors: Zhu Tao , Yang Jing , He Bian
Published: May 2023

The intensity and location of boreal summer extratropical intraseasonal oscillations along the subtropical westerly jet (EISO-SJ) are crucial in triggering and distributing extreme events over Eurasia. Based on numerical experiments, this study distinguishes the orographic mechanical and surface thermal forcing of the Tibetan–Iranian Plateau (i.e. TIP-MF and TIP-TF) on EISO-SJ. The TIP-MF primarily modulates the amplitude of EISO-SJ that strengthens over the upstream and weakens over the downstream. Comparatively, the TIP-TF not only reduces/increases the intensity of EISO-SJ over the TIP upstream/downstream, but also significantly migrates the track of EISO-SJ northward. Further analysis demonstrates that the changes of the westerly jet, eddy energy propagation and energy conversion are consistent with the track and amplitude changes of EISO-SJ. This study indicates the variations of the TIP surface sensible heating in interannual variation and global change, as well as the terrain uplift of the TIP in paleoclimate influence on the mid-latitude subseasonal variation.
Polyurethane/halloysite nano tubes/sericin based electrospun nanocomposite for sustained drug release
Authors: Joshi Mangala , Roy Sukumar , TV Ayeshvaryaa
Published: May 2023

In this study, the feasibility of the production of electrospun nanofibre composite mainly for biomedical applications is reported. Biocompatible polyether-based polyurethane, natural proteinaceous polymer silk sericin (SS) and natural inorganic nanoclay halloysite as a drug carrier with a model drug chlorhexidine acetate were used to produce nanofibres by electrospinning technique. Sericin was extracted from Bombyx mori silk cocoons by high pressure high temperature (HT-HP) degumming. Chlorhexidine acetate (CA), an antimicrobial agent, was loaded into halloysite nanotubes (HNTs) at different weight ratios, and 1:1 weight ratio showed the maximum loading which was confirmed by TGA and XRD analysis. Electrospinning of polymer solution with different compositions of polyurethane, sericin, CA and CA-HNTs was conducted at 10% w/v concentration, 20 kV voltage, 15 μl min−1 flow rate and 10 cm distance which resulted in the formation of bead-free uniform fibres. Antimicrobial activity of nanofibrous webs was evaluated by the disc diffusion method (AATCC 90) and it was found that CA and CA-HNT loaded nanofibres show sustained antibacterial action against both the Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria. The CA-HNT and sericin/CA-HNT loaded nanofibres showed controlled release of CA. In addition, the cytocompatibility assessment of developed nanofibrous composites showed good biocompatibility. Hence the produced composite nanofibre can serve as an excellent material for sustained drug release for various biomedical applications.
Sharp ballistic p–n junction at room temperature using Zn metal doping of graphene
Authors: Leontis Ioannis , Prando Gabriela Augusta , Anastasiou Konstantinos Andreas , Bacon Agnes , Craciun Monica Felicia , Russo Saverio
Published: May 2023

Ballistic graphene p–n junctions (GPNJs) are uniquely suited to develop electrical counterparts of optical circuits as the large transparency enables a better carrier modulation in their interfaces than the diffusive junctions. Here we demonstrate a low-cost and scalable method for the fabrication of ballistic planar GPNJs based on the deposition of physisorbed Zn adatoms. A detailed study of spatially resolved Raman spectroscopy through a quartz transparent substrate enables the accurate mapping of the charge doping and strain across the graphene/Zn interface and underneath the metal layer. At the same time, the electrical measurements of transistor structures with varying channel length, i.e. transfer length electrical measurements, and their modeling reveal the ballistic nature of the charge transport up to room temperature.
Effects of annealing on particle size and pore size distribution of hydrothermally synthesized BaTiO3 nanopowders and their grain-growth kinetics during sintering
Authors: Lee Jongbeom , Jeong Jinyoung , Jeong Haguk
Published: May 2023

With an increase in the annealing temperature, the hydrothermally synthesized BaTiO3 nanopowders increased in particle sizes from 100 to 260 nm and decreased in pore volume from 7.2 to 2.82 cm3 g−1, while the pore size remained constant at 3.06 nm. Samples with different initial particle sizes were sintered in the temperature range of 1210 °C–1300 °C and for periods of 0.5–48 h at 1270 °C. The kinetic grain-growth exponent of the sintered BaTiO3 samples, n, was proportional to the increase of an initial particle size and the decrease of pore volume, and the grain growth obeyed the Arrhenius equation. The activation energies for the grain growth of the sintered BaTiO3 samples with initial particle size of 100, 155 and 260 nm were 737, 702 and 755 kJ mol−1, respectively, indicating that the activation energy was independent of the initial particle size in the range of 100–300 nm under identical purity conditions, and pore volume was supposed to be attributed to the velocity of grain growth.
Tree stems are a net source of CH4 and N2O in a hemiboreal drained peatland forest during the winter period
Authors: Ranniku Reti , Schindler Thomas , Escuer-Gatius Jordi , Mander Ülo , Machacova Katerina , Soosaar Kaido
Published: May 2023

Nutrient-rich northern peatlands are often drained to enhance forest productivity, turning peatland soils into sinks of methane (CH4) and sources of nitrous oxide (N2O). However, further attention is needed on CH4 and N2O dynamics during the winter period to fully understand the spatio-temporal variability of fluxes. Besides soil, tree stems can also emit CH4 and N2O. However, stem contribution is not considered in most biogeochemical models. We determined the temporal dynamics of winter-time CH4 and N2O fluxes in a drained peatland forest by simultaneously measuring stem and soil fluxes and exploring the relationships between gas fluxes and soil environmental parameters. During sampling (October 2020–May 2021), gas samples from Downy Birch (Betula pubescens) and Norway Spruce (Picea abies) trees were collected from different tree heights using manual static chambers and analysed using gas chromatography. Soil CH4 and N2O concentrations were measured using an automated dynamic soil chamber system. Tree stems were a net source of CH4 and N2O during the winter period. The origin of stem CH4 emissions was unclear, as stem and soil CH4 fluxes had opposite flux directions, and the irregular vertical stem flux profile did not indicate a connection between stem and soil fluxes. Stem N2O emissions may have originated from the soil, as emissions decreased with increasing stem height and were driven by soil N2O emissions and environmental parameters. Soil was a net sink for CH4, largely determined by changes in soil temperature. Soil N2O dynamics were characterised by hot moments—short periods of high emissions related to changes in soil water content. Tree stem emissions offset the soil CH4 sink by 14% and added 2% to forest floor N2O emissions. Therefore, CH4 and N2O budgets that do not incorporate stem emissions can overestimate the sink strength or underestimate the total emissions of the ecosystem.