bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Eleven-Membered Cyclic Urea Fused Quinazolinones
Authors: Kaeobamrung Juthanat , Saebang Yotsakorn , Rukachaisirikul Vatcharin
Published: March 2022

Straightforward synthesis of quinazolinones having N-fused medium-sized ring urea was accomplished. Key intermediates were tert-butyl {2-[4-oxo-2-(4-oxopentyl)quinazolin-3(4H)-yl]ethyl}carbamates derived from copper-catalyzed domino reaction of tert-butyl [2-(2-iodobenzamido)ethyl]carbamates and cyclic enaminones. Steric hindrance of cyclic enaminones played an important role in the formation of quinazolinone ring. The eleven-membered ring urea moiety was readily achieved by direct cyclization using 1,1′-carbonyldiimidazole (CDI) of diamino intermediate generated by readily reductive amination and deprotection of tert-butyl {2-[4-oxo-2-(4-oxopentyl)quinazolin-3(4H)-yl]ethyl}carbamates.
Total Syntheses of Spirooliganones A and B
Authors: Morita Masao , Nemoto Nobuaki , Ohmori Ken
Published: March 2022

This paper describes the total syntheses of spirooliganones A and B, which provides control over the stereochemistry of the spiro center via a cascade reaction involving the in situ formation of an o-quinone methide and a hetero-Diels–Alder reaction.
Unsuspecting Lead Points Causing Nonobstructing Intussusceptions in Pediatric Patients Presenting with Chronic Pain Abdomen
Authors: Jain Garima , Royal Nirmala , Sharma Pramila , Bhandari Anu , Mendiratta Kuldeep
Published: March 2022

Intussusception is one of the common causes of bowel obstruction in pediatric age group and is of idiopathic variety in most of the cases. Nonobstructing intussusception presenting with nonspecific symptoms (or chronic pain abdomen) is rare and usually clinically misdiagnosed/difficult to diagnose. The authors present a pictorial review of 10 cases of pediatric nonobstructing intussusception presenting with acute/chronic abdominal pain which were not suspected clinically but diagnosed with a pathologic lead point radiologically.
On electron temperature rise in divertor relevant recombining plasma along magnetic field line
Authors: Takahashi H. , Winarto M. N. , Okamoto A. , Boonyarittipong P. , Seino T. , Kusabiraki K. , Sakata Y. , Yoshimura K. , Nishimura R. , Kitajima S. , Matsuyama A. , Tobita K.
Published: March 2022

The rise of electron temperature along the magnetic field line was clearly observed in divertor relevant recombining plasma, even though there was no additional electron heating source. Electron temperature obtained at recombination front was approximately 0.5 eV, whereas it increased up to greater than 1 eV at downstream of recombination front. Although this temperature rise is likely common in detached or recombining plasmas, the mechanism has not been understood yet. This report provides a reasonable interpretation of temperature rise along the magnetic field line, for the first time: depletion of low energy electrons due to volumetric recombination leads to deformation of electron energy distribution, resulting in an apparent increase in electron temperature. Our experiment supports this interpretation in that the experimentally observed electron temperature showed good agreement with calculated effective electron temperature.
Effects of swimming environment on bacterial motility
Authors: Kim Dokyum , Kim Yongsam , Lim Sookkyung
Published: March 2022

Swimming trajectories of bacteria can be altered by environmental conditions, such as background flow and physical barriers, that limit the free swimming of bacteria. We present a comprehensive model of a bacterium that consists of a rod-shaped cell body and a flagellum which is composed of a motor, a hook, and a filament. The elastic flagellum is modeled based on the Kirchhoff rod theory, the cell body is considered to be a rigid body, and the hydrodynamic interaction of a bacterium near a wall is described by regularized Stokeslet formulation combined with the image system. We consider three environmental conditions: (1) a rigid surface is placed horizontally and there is no shear flow, (2) a shear fluid flow is present and the bacterium is near the rigid surface, and (3) while the bacterium is near the rigid surface and is under shear flow, an additional sidewall which is perpendicular to the rigid surface is placed. Each environmental state modifies the swimming behavior. For the first condition, there are two modes of motility, trap and escape, whether the bacterium stays near the surface or moves away from the surface as we vary the physical and geometrical properties of the model bacterium. For the second condition, there exists a threshold of shear rate that classifies the motion into two types of paths in which the bacterium takes either a periodic coil trajectory or a linear trajectory. For the last condition, the bacterium takes upstream motility along the sidewall for lower shear rates and downstream motility for larger shear flow rates.
New International Formulation for the Thermal Conductivity of Heavy Water
Authors: Huber M. L. , Perkins R. A. , Assael M. J. , Monogenidou S. A. , Hellmann R. , Sengers J. V.
Published: March 2022

The International Association for the Properties of Water and Steam has adopted new formulations for the thermodynamic and transport properties of heavy water. This manuscript describes the development of a formulation for the thermal conductivity of heavy water that was adopted as an international standard in 2021. It is consistent with the equation of state adopted in 2017, revised slightly in 2018, and is valid for fluid states up to 825 K and 250 MPa with uncertainties ranging from 1.5% to 6% depending on the state point. Comparisons with experimental data and with an earlier thermal-conductivity formulation are presented. The 2021 formulation accounts for the critical enhancement of the thermal conductivity, which was not incorporated in the previous formulation. Furthermore, in the zero-density limit, the 2021 formulation is based on thermal conductivity values at temperatures from 250 to 2500 K obtained from the kinetic theory of polyatomic gases. In addition, the 2021 formulation is applicable in a larger range of pressures than the previous formulation.
Role of internal flow in squid-inspired jet propulsion
Authors: Bi Xiaobo , Zhu Qiang
Published: March 2022

We numerically investigate the dynamics of a self-propelled system that swims by using intermittent jet propulsion through cyclic body deformations. Unlike existing studies, the focus of the current work is on characteristics of internal flow field and its effect on the thrust generation and energetics of the system. Our results indicate that the inertia of the internal flow plays a minor role in thrust generation in comparison with the momentum flux and the normal stress at the nozzle. By examining the energy pathways in both inflation (recovery) and deflation (power) phases, we illustrate that the energy dissipation inside the pressure chamber occurs mostly in the inflation phase, during which the energy transferred from the solid structure to the fluid is mostly damped out and wasted. Based on this analysis, we propose a novel performance enhancement method by using a variable nozzle to reduce the energy waste in the inflation phase. In a sample case, this strategy not only increases the propulsive efficiency by 118% but also increases the forward speed by 25%. Furthermore, we have studied the effect of solid structures inside the pressure chamber. Our results suggest these structures cause a decline in the efficiency, especially if they are close to the nozzle.
Self-propulsion of Janus particles in the free molecular regime
Authors: Zhang Kexue , Xu Liyuan , Li Yunyun , Marchesoni Fabio , Wang Jun , Xia Guodong
Published: March 2022

The self-propulsion of a Janus particle suspended in a dilute gas at equilibrium is investigated in the free molecular regime. The Janus particle consists of two hemispheres with different momentum accommodation factors; the particle and the surrounding gas are held at different constant temperatures. Based on the gas kinetic theory, we calculate the particle's self-propulsion and drag force. We conclude that self-propulsion occurs only under the condition that the particle is hotter/colder than the suspension gas, and the self-propulsion force is proportional to the difference of the momentum accommodation factors and directed along the symmetry axis. The drag force, instead, is corrected by a term proportional to the average of the momentum accommodation factors. Our analytical results are confirmed by numerical Monte Carlo simulations.
Developmental and evolutionary constraints on olfactory circuit selection
Authors: Hiratani Naoki , Latham Peter E.
Published: March 2022

Significance

In this work, we explore the hypothesis that biological neural networks optimize their architecture, through evolution, for learning. We study early olfactory circuits of mammals and insects, which have relatively similar structure but a huge diversity in size. We approximate these circuits as three-layer networks and estimate, analytically, the scaling of the optimal hidden-layer size with input-layer size. We find that both longevity and information in the genome constrain the hidden-layer size, so a range of allometric scalings is possible. However, the experimentally observed allometric scalings in mammals and insects are consistent with biologically plausible values. This analysis should pave the way for a deeper understanding of both biological and artificial networks.
Microglia regulate chandelier cell axo-axonic synaptogenesis
Authors: Gallo Nicholas B. , Berisha Artan , Van Aelst Linda
Published: March 2022

Significance

Chandelier cells (ChCs) are a unique type of GABAergic interneuron that form axo-axonic synapses exclusively on the axon initial segment (AIS) of neocortical pyramidal neurons (PyNs), allowing them to exert powerful yet precise control over PyN firing and population output. The importance of proper ChC function is further underscored by the association of ChC connectivity defects with various neurological conditions. Despite this, the cellular mechanisms governing ChC axo-axonic synapse formation remain poorly understood. Here, we identify microglia as key regulators of ChC axonal morphogenesis and AIS synaptogenesis, and show that disease-induced aberrant microglial activation perturbs proper ChC synaptic development/connectivity in the neocortex. In doing so, such findings highlight the therapeutic potential of manipulating microglia to ensure proper brain wiring.
Bisphenol A replacement chemicals, BPF and BPS, induce protumorigenic changes in human mammary gland organoid morphology and proteome
Authors: Winkler Juliane , Liu Pengyuan , Phong Kiet , Hinrichs Johanna H. , Ataii Nassim , Williams Katherine , Hadler-Olsen Elin , Samson Susan , Gartner Zev J. , Fisher Susan , Werb Zena
Published: March 2022

Significance

Bisphenol A (BPA), found in many plastic products, has weak estrogenic effects that can be harmful to human health. Thus, structurally related replacements—bisphenol S (BPS) and bisphenol F (BPF)—are coming into wider use with very few data about their biological activities. Here, we compared the effects of BPA, BPS, and BPF on human mammary organoids established from normal breast tissue. BPS disrupted organoid architecture and induced supernumerary branching. At a proteomic level, the bisphenols altered the abundance of common targets and those that were unique to each compound. The latter included proteins linked to tumor-promoting processes. These data highlighted the importance of testing the human health effects of replacements that are structurally related to chemicals of concern.
The multi-factor modulated biogenesis of the mitochondrial multi-span protein Om14
Authors: Zhou Jialin , Jung Martin , Dimmer Kai S. , Rapaport Doron
Published: March 2022

The mitochondrial outer membrane (MOM) harbors proteins that traverse the membrane via several helical segments and are called multi-span proteins. To obtain new insights into the biogenesis of these proteins, we utilized yeast mitochondria and the multi-span protein Om14. Testing different truncation variants, we show that while only the full-length protein contains all the information that assures perfect targeting specificity, shorter variants are targeted to mitochondria with compromised fidelity. Employing a specific insertion assay and various deletion strains, we show that proteins exposed to the cytosol do not contribute significantly to the biogenesis process. We further demonstrate that Mim1 and Porin support optimal membrane integration of Om14 but none of them are absolutely required. Unfolding of newly synthesized Om14, its optimal hydrophobicity, and higher fluidity of the membrane enhanced the import capacity of Om14. Collectively, these findings suggest that MOM multi-span proteins follow different biogenesis pathways in which proteinaceous elements and membrane behavior contribute to a variable extent to the combined efficiency.
Iron out KRAS-driven cancer
Authors: Lei Guang , Gan Boyi
Published: March 2022

How to specifically target oncogenic KRAS-driven cancers while sparing normal tissues remains an unmet need in cancer therapy. In this issue of JEM, Jiang et al. (2022. J. Exp. Med.https://doi.org/10.1084/jem.20210739) leveraged KRAS-induced iron addiction in cancer cells to design a clever drug delivery approach to enable selective inhibition of KRAS signaling in mutant KRAS tumors but not in normal tissues, offering a new strategy for treating this largely incurable disease.
Bilateral comparison of 1 Ω and 10 kΩ standards (ongoing BIPM key comparisons BIPM.EM-K13.a and 13.b) between the INMETRO (Brazil) and the BIPM.
Authors: Rolland B , Stock M , Gournay P , Oliveira V Coutinho de , Carvalho H R , Landim R P
Published: March 2022

Main text

This report gives the result of a bilateral comparison of resistance between the INMETRO (Brazil) and the BIPM carried out from November 2020 to September 2021. Two 1 Ω and two 10 kΩ travelling standards belonging to the BIPM were used. The comparison was carried out with an 'A-B-A' pattern of measurements; the standards were measured first at the BIPM for a period of about one month, then for a period of about two months at the INMETRO, and finally again at the BIPM. The measurand was the 4 terminal dc resistance at low power. The BIPM was the pilot laboratory, and the comparison forms part of the ongoing BIPM key comparisons BIPM.EM-K13.a (for 1 Ω) and BIPM.EM-K13b (for 10 kΩ).

The results from the INMETRO and the BIPM were found to be in good agreement, with a difference D smaller than the relative expanded uncertainty Uc (95% confidence, k = 2) giving D = 0.010 × 10-6, Uc = 0.068 x 10-6 for 1 Ω and D = 0.026 x 10-6, Uc = 0.036 x 10-6 for 10 kΩ.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Measurement of short gauge blocks by interferometry
Authors: Prieto Emilio , Rodriguez Joaquin , Bartl Guido , Pirée Hugo , Meli Felix , Picotto Gian Bartolo , Franco Mauro , Balling Petr
Published: March 2022

Main text

This comparison piloted by CEM (ES), started in Nov 19 and concluded with some delay in February 21. Participants were CEM, PTB, SMD, METAS, INRIM and CMI.

Two sets of eight gauge blocks in both steel and ceramic were circulated, covering the range 1.5 mm to 100 mm. The gauge blocks were of rectangular cross section and comply with the calibration grade K of ISO 3650 standard.

Main measurand to be reported was the deviation ec of the central length lc from the nominal length ln of the gauge block. The arithmetic mean of the two values for wringing on both faces was considered as representative for ec In cases where only one face was wrung the corresponding value was reported as the result. As an auxiliary measurand the difference of the found deviations dc when the block was wrung to face A and face B, respectively, was reported.

The uncertainty of measurement was evaluated according to the ISO Guide to the Expression of Uncertainty in Measurement. For efficient evaluation and subsequent assessment of CMC claims an uncertainty statement in the functional form was preferred.

The key comparison reference value (KCRV) was calculated on a gauge-per-gauge basis as the weighted mean of the participants' results. The check for consistency of the comparison results with their associated uncertainties was based on Birge ratio and the degrees of equivalence for each laboratory and gauge block with respect to the KCRV were evaluated by using En values, in line with the WG-MRA-KC-report-template.

Looking at the principal measurand, the central length ec, there were in total 11 values out of 96 not compatible with the final reference values, this representing the 11.4 % of the full set of results, considering both materials. With respect to the difference in central length from wringing in faces A and B, dc, there were in total 6 values not compatible with the reference value, this representing a 6.5 % of the 92 values communicated.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the KRISS, Republic of Korea, and the BIPM in medium-energy x-rays
Authors: Burns D T , Kessler C , Yi Chul-Young , Kim Yun Ho
Published: March 2022

Main text

A key comparison has been made between the air-kerma standards of the KRISS, Republic of Korea, and the BIPM in the medium-energy x-ray range. The results show the standards to be in agreement at the limit of the expanded uncertainty of the comparison of 4.4 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Cathodoluminescence and EBIC investigations of stacking fault expansion in 4H-SiC due to e-beam irradiation at fixed points
Authors: Yakimov E E , Yakimov E B
Published: March 2022

The effect of e-beam irradiation in the local and scan modes on the stacking fault expansion in 4H-SiC has been studied. It is shown that the distance, at which the e-beam affects the glide of partial dislocations driving the stacking fault expansion, does not exceed 10–12 μm. The dislocations were found to glide as straight lines with a velocity independent of their length, even when this length essentially exceeds the size of excitation volume. The irradiation at fixed points allows to separate the excess carrier effects on the kink formation and kink migration. The results obtained were explained under an assumption that the irradiation is necessary only to stimulate the kink pair formation and then the kinks can migrate without any excitation. That could mean that the barrier for the kink migration along Si-core 30° partial dislocations in 4H-SiC is very small.
Estimation of plasma properties using an extended Kalman filter with plasma global models
Authors: Greve C M , Hara K
Published: March 2022

A physically-constrained extended Kalman filter (EKF) is applied to various zero-dimensional global models for the estimation of plasma properties using time-dependent experimental data such as the plasma density or ion flux. The capability of the EKF is demonstrated to estimate unknown system states simultaneously, such as reaction rate coefficients and the absorbed electron input power, which can be difficult, if not impossible, to measure experimentally. Global models accounting for pure argon reactions and argon-oxygen reactions are used in this work to demonstrate the ability of the filter to estimate dynamic and complex systems. The results obtained from the EKF plasma global model illustrate that model-data fusion techniques can be used to estimate plasma properties and processes for time-varying systems, such as pulsed discharges.
Quantifying the interpolation uncertainty of radiosonde humidity profiles
Authors: Colombo Pietro , Fassò Alessandro
Published: March 2022

The global climate observing system Reference Upper Air Network (GRUAN) provides reference measurements of the essential climate variables and their measurement uncertainty. An important aspect of the measurement uncertainty is the interpolation uncertainty. This problem arises, for example, when GRUAN processes atmospheric profiles collected by Vaisala RS41 radiosondes. For various reasons, the radiosonde sensor may fail to collect some values along the vertical profile in the atmosphere. As a consequence, estimation techniques to fill the data gaps and to provide an evaluation of the related interpolation uncertainty are welcome. This paper aims to understand and quantify the interpolation uncertainty of the relative humidity (RH). In particular, we consider linear and Gaussian process interpolation either unidimensional or multidimensional. We provide results in terms of interpolation distance in seconds, which measures the distance of an interpolated data from the interpolating data. We also consider measurement altitude and launch site. Although the Gaussian interpolation results to be generally better than linear interpolation, the difference in uncertainty is relatively small. The average column uncertainty difference is in the order of 0.2% and for large data gaps around 0.4%. The interpolation uncertainty is larger in the lower atmosphere. For example at 2–4 km altitude, the uncertainty is around 2% at 10 s distance, around 5% at 40 s and 10% at 90 s. In the upper atmosphere, RH and its uncertainty decrease. For example, at 14–16 km altitude, the latter is smaller than 2% RH at all interpolation distances.
Enhancing the incorporation of Sn in vapor–liquid–solid GeSn nanowires by modulation of the droplet composition
Authors: Zeghouane Mohammed , Hijazi Hadi , Bassani Franck , Lefevre Gauthier , Martinez Eugenie , Luciani Thierry , Gentile Pascal , Dubrovskii Vladimir G , Salem Bassem
Published: March 2022

We report on the influence of the liquid droplet composition on the Sn incorporation in GeSn nanowires (NWs) grown by the vapor−liquid−solid (VLS) mechanism with different catalysts. The variation of the NW growth rate and morphology with the growth temperature is investigated and 400 °C is identified as the best temperature to grow the longest untapered NWs with a growth rate of 520 nm min−1. When GeSn NWs are grown with pure Au droplets, we observe a core–shell like structure with a low Sn concentration of less than 2% in the NW core regardless of the growth temperature. We then investigate the impact of adding different fractions of Ag, Al, Ga and Si to Au catalyst on the incorporation of Sn. A significant improvement of Sn incorporation up to 9% is obtained using 75:25 Au–Al catalyst, with a high degree of spatial homogeneity across the NW volume. Thermodynamic model based on the energy minimization at the solid–liquid interface is developed, showing a good correlation with the data. These results can be useful for obtaining technologically important GeSn material with a high Sn content and, more generally, for tuning the composition of VLS NWs in other material systems.
Building core–shell FeSe2@C anode electrode for delivering superior potassium-ion batteries
Authors: Liu Lingli , Yu Lei , Hu Lei , Meng Xianghe , Liang Sheng , Ge Jinlong , Wu Yun , Deng Chonghai
Published: March 2022

Inferior electrical conductivity and large volume variation are two disadvantages of metal selenides. In this work, we have designed a core–shell structure of FeSe2@C composite with low cost using facile hydrothermal method. The FeSe2 particles as the ‘core’ and the carbon layer as the ‘shell’ displayed good synergistic effect that attributed to alleviate volume expansion of electrode and improving the electrical conductivity, which achieved the fast potassium storage. The core–shell structural FeSe2@C electrode achieved 286 mA h g−1 at 1 A g−1 over 1000 cycles with 99.8% coulombic efficiency and delivered excellent rate capacity with 273 mA h g−1 at 2 A g−1, which was ascribed to dispersed FeSe2 particles and the strong carbon shell coating. This work will provide the basis for the further development of the application of metal selenides in the field of flexible electrodes.
Control one-dimensional length of rectangular pore on graphene membrane for better desalination performance
Authors: Chen Shenghui , Ding Jiaqi , Li Quanjiang , He Di , Liu Yanli , Wang Li , Lyu Qiang , Wang Meishan
Published: March 2022

At present, there is a general contradiction between permeability and selectivity of reverse osmosis (RO) membranes for desalination; a membrane with higher water permeability will give a lower salt rejection or selectivity, and vice versa. In this work, single-layer nanoporous graphene is used as RO membrane to investigate the effects of pore shape to reduce this contradiction by molecular dynamics simulations. Two kinds of pores (round and rectangular pores) with different sizes are simulated. For round pore, although the water permeability increases with the increase of the pore size, the salt rejection rate drops rapidly. For rectangular pore, reasonable designed pore structure can achieve improved water permeability and high salt rejection of graphene membrane by keeping one-dimensional length (i.e. the width) of the pore less than the size of the hydrated ions and increasing the other dimensional length. The restriction of one dimension can prevent the passage of hydrated ions through the pore effectively. This ‘one-dimensional restriction’ provides a simple strategy for designing RO membrane with variable pore structures to obtain a better desalination performance.
Model-based machine learning for the recovery of lateral dose profiles of small photon fields in magnetic field
Authors: Looe Hui Khee , Blum Isabel , Schönfeld Ann-Britt , Tekin Tuba , Delfs Björn , Poppe Björn
Published: March 2022

Objective. To investigate the feasibility to train artificial neural networks (NN) to recover lateral dose profiles from detector measurements in a magnetic field. Approach. A novel framework based on a mathematical convolution model has been proposed to generate measurement-less training dataset. 2D dose deposition kernels and detector lateral fluence response functions of two air-filled ionization chambers and two diode-type detectors have been simulated without magnetic field and for magnetic field B = 0.35 and 1.5 T. Using these convolution kernels, training dataset consisting pairs of dose profiles

D

x
,
y

and signal profiles

M

x
,
y

were computed for a total of 108 2D photon fluence profiles

ψ

(
x
,
y
)

(80% training/20% validation). The NN were tested using three independent datasets, where the second test dataset has been obtained from simulations using realistic phase space files of clinical linear accelerator and the third test dataset was measured at a conventional linac equipped with electromagnets. Main results. The convolution kernels show magnetic field dependence due to the influence of the Lorentz force on the electron transport in the water phantom and detectors. The NN show good performance during training and validation with mean square error reaching a value of 1e-6 or smaller. The corresponding correlation coefficients R reached the value of 1 for all models indicating an excellent agreement between expected

D

x
,
y

and predicted

D

pred

x
,
y

.

The comparisons between

D

x
,
y

and

D

pred

x
,
y

using the three test datasets resulted in gamma indices (1 mm/1% global) <1 for all evaluated data points. Significance. Two verification approaches have been proposed to warrant the mathematical consistencies of the NN outputs. Besides offering a correction strategy not existed so far for relative dosimetry in a magnetic field, this work could help to raise awareness and to improve understanding on the distortion of detector’s signal profiles by a magnetic field.
Phase and group velocities for shear wave propagation in an incompressible, hyperelastic material with uniaxial stretch
Authors: Rouze Ned C , Caenen Annette , Nightingale Kathryn R
Published: March 2022

Objective. Determining elastic properties of materials from observations of shear wave propagation is difficult in anisotropic materials because of the complex relations among the propagation direction, shear wave polarizations, and material symmetries. In this study, we derive expressions for the phase velocities of the SH and SV propagation modes as a function of propagation direction in an incompressible, hyperelastic material with uniaxial stretch. Approach. Wave motion is included in the material model by adding incremental, small amplitude motion to the initial, finite deformation. Equations of motion for the SH and SV propagation modes are constructed using the Cauchy stress tensor derived from the strain energy function of the material. Group velocities for the SH and SV propagation modes are derived from the angle-dependent phase velocities. Main results. Sample results are presented for the Arruda–Boyce, Mooney–Rivlin, and Isihara material models using model parameters previously determined in a phantom. Significance. Results for the Mooney–Rivlin and Isihara models demonstrate shear splitting in which the SH and SV propagation modes have unequal group velocities for propagation across the material symmetry axis. In addition, for sufficiently large stretch, the Arruda–Boyce and Isihara material models show cusp structures with triple-valued group velocities for the SV mode at angles of roughly 15° to the material symmetry axis.
High-dose femtosecond-scale gamma-ray beams for radiobiological applications
Authors: McAnespie C A , Streeter M J V , Rankin M , Chaudhary P , McMahon S J , Prise K M , Sarri G
Published: March 2022

Objective. In the irradiation of living tissue, the fundamental physical processes involved in radical production typically occur on a timescale of a few femtoseconds. A detailed understanding of these phenomena has thus far been limited by the relatively long duration of the radiation sources employed, extending well beyond the timescales for radical generation and evolution. Approach. Here, we propose a femtosecond-scale photon source, based on inverse Compton scattering of laser-plasma accelerated electron beams in the field of a second scattering laser pulse. Main results. Detailed numerical modelling indicates that existing laser facilities can provide ultra-short and high-flux MeV-scale photon beams, able to deposit doses tuneable from a fraction of Gy up to a few Gy per pulse, resulting in dose rates exceeding 1013 Gy/s. Significance. We envisage that such a source will represent a unique tool for time-resolved radiobiological experiments, with the prospect of further advancing radio-therapeutic techniques.
Development of a high-resolution, high-speed impact piezoelectric actuator using cross-frequency band method
Authors: Li Chen , Li Ruijun , Zhao Mingfei , Wang Ya , Wei Yongqing , Huang Qiangxian , Pan Qiaosheng
Published: March 2022

A novel impact piezoelectric actuator is proposed in this paper to achieve cross-scale driving, which can realise high resolution and high speed. The piezoelectric actuator is mainly composed of four diamond-shaped flexible hinges, which can consider a certain stiffness and flexibility. The operating principle of the piezoelectric actuator is introduced. The actuator is excited by two sinusoidal waves with a frequency ratio of 1:2 to achieve impact drive at quasi-static state. The appropriate structural parameters are obtained by simulation. The actuator is designed to make the frequency ratio of first and second vibration modes 1:2, which can achieve impact drive at resonant state. The prototype is fabricated, and the characteristics are tested. The measured resonant frequency ratio is consistent with the simulated value. Experimental results show that when the prototype works at quasi-static state, the resolution is 37 nm with driving voltages of 12 Vp-p; at resonant state, the no-load maximum speed is 125.43 mm s−1 and the maximum load is 0.5 N when the driving frequency and voltages are 1.95 kHz, 40 Vp-p and 3.90 kHz, 160 Vp-p, respectively. The proposed actuator can be used for precision positioning and can improve the accuracy and the efficiency of processing instruments.
High critical current solution derived YBa2Cu3O7 films grown on sapphire
Authors: Pop C , Barusco P , Vlad R , Queralto A , Gupta K , Almog B , Saraf A , Deutscher G , Granados X , Puig T , Obradors X
Published: March 2022

Superconducting fault current limiters (SFCLs) are very attractive devices which require to increase its robustness against the destructive hot spots. The use of sapphire substrates to grow YBa2Cu3O7 (YBCO) films is a very attractive approach due to its high thermal conductivity. This article reports the growth of microcrack-free, epitaxial YBCO layers by chemical solution deposition (CSD) on Ce1−x
Zr
x
O2 (CZO)/yttrium-stabilized zirconia/r-cut barely polished sapphire (BPS) substrates which can be produced in long lengths at low cost. The surface quality of the r-cut sapphire and its role on the epitaxy of CZO and YBCO layers is discussed. The issue of the microcrack generation in YBCO layers is investigated in relation to the film thickness, the growth process and the oxygenation annealing step. We demonstrate that microcracks formation is related to the in-plane tensile stress generated during the oxygenation step instead of the differential thermal expansion effects and thus it can be minimized through an adapted oxygenation process. We have shown that CSD growth of YBCO films with thicknesses up to 400 nm and attractive superconducting properties (J
C ∼ 1.9 MA cm−2 at 77 K) can be achieved on BPS substrates which can be used at moderate cost for SFCL devices.
Quantum biology. π–π entanglement signatures in protein-DNA interactions
Authors: D’Acunto Mario
Published: March 2022

The biological functions of DNA are carried out by individual proteins that interact with specific sequences along the DNA in order to prime the molecular processes required by the cellular metabolism. Protein-DNA interactions include DNA replication, gene expression and its regulation, DNA repair, DNA restriction and modification by endonucleases, generally classified as enzymatic functions, or transcription factors functions. To find specific binding target sequences and achieve their aims, in less than one second proteins operate in symbiosis with a crowded cellular environment, identifying extremely small cognate sequences along the DNA chain, which range from 15–20 bps for repressors to 4–6 bps for restriction enzymes. In a previous work, we proposed that the extraordinary ability of proteins to identify consensus sequences on DNA in a short time appears to be dependent on specific quantum signatures such as the entanglement ofπ–πelectrons between DNA nucleotides and protein amino acids, where the couple ofπelectrons function as a radical pair, oneπelectron is located on a specific site of sequence to be identified and the other one performs a quantum walk to identify possible sites of consensus sequence. In this paper, we use the restriction endonucleases enzymes, EcoRV and EcoRI as a case study. These enzymes are able to recognize 3′-GATACT-5′ or 3′-GAATCT-5′ sequences, respectively. We exploit the analogy of a coin operator with a Bloch sphere to demonstrate that the entanglement betweenπ–πelectrons generated at the contacts on specific GA dimers between proteins and DNA relies on the spin of the electrons that form an initial singlet state. The latter is a maximally entangled state so that the identification of specific nucleotides is associated with the formation of singlet states. On the other hand, during the identification of subsequent GA dimers, the spin–orbit interaction on walkingπelectron induces triplet transitions so that singlet–triplet transitions should manifest an experimentally measurable effect. We propose that the possible experimental evidence of entanglement betweenπ–πelectrons may be due to the phosphorescence signal correspondence to triplet decay processes.
Transmission electromagnetic beam splitter based on double-sided all dielectric microstructure
Authors: Wei Hongling , Cui Fuyi , Guo Weigang , Wu Yinglai
Published: March 2022

We propose a transmission type dual beam splitter based on all-dielectric encoded metasurface. In order to improve the efficiency of the device, we propose to construct the coding metasurface using double-sided all-dielectric cylindrical cell structure. Based on the electromagnetic dipole resonance characteristics of the all-dielectric resonator, two all-dielectric elements with transmission phase difference π were obtained, and 1-bit coded metasurface was constructed to achieve beam splitting characteristics of incident waves. Based on the finite integral method, we numerically simulate the far-field scattering characteristics of coded metasurface beam splitter. It is found that the number of digital repeats of coding unit particles has a great influence on beam splitting when constructing coding metasurface due to the coupling effect between particles. The energy ratio of double beam splitting can be continuously regulated by changing the incident angle. The dual-beam splitter we designed also has broadband characteristics.
Novel ELC-like and Z-shaped plasmonic waveguides to reach ultra-strong field confinements
Authors: Aziz Asad
Published: March 2022

In this paper, two novel waveguides with ELC like-shaped and Z-shaped grooves have been proposed to achieve highly efficient and strongly confined spoof surface plasmon polaritons (SSPPs) propagation. Low-dispersion bands can be realized by such structures with tight field confinement of SSPPs, resulting in size miniaturization of the proposed waveguides. Specifically, our method yields deep physical insight into the effect that the geometrically induced modifications of the supporting structure has on the dispersion properties and field confinement capabilities of SSPPs. In comparison, SSPP waveguide results presented in Aziz (2021 Results Opt.
5 100116) are given which is regarded to have stronger SSPPs field confinement as compared to previously reported different grooves shapes based SSPP waveguides. It is found that the dispersion and waveguide propagation characteristics can be directly manipulated by varying the geometrical parameters of the horizontal and slanted slits of Z-shaped and ELC-like shaped plasmonic waveguides without increasing the lateral dimension of the waveguides. Based on this waveguiding scheme, the proposed waveguides exhibit much lower asymptotic frequency of the dispersion relation and even tighter SSPPs field confinement than I-shaped plasmonic waveguide. Then, broadband transitions with a tapered metallic strip and an array of graded height ELC-like and Z-shaped units with good impedance matching and high mode conversion efficiency are designed. Fully controlled field enhancement functionality has been performed, by using such metamaterial particles in the form of grooves, decorated in SSPP waveguide. Simulated results have demonstrated that the proposed SSPP waveguides have much stronger field confinement than the highly efficient I-shaped grooves based SSPP waveguide. The proposed waveguides can be a significant contribution towards the advancement of plasmonic functional devices and integrated circuits in microwave frequencies.
Intracortical microstimulation pulse waveform and frequency recruits distinct spatiotemporal patterns of cortical neuron and neuropil activation
Authors: Stieger Kevin C , Eles James R , Ludwig Kip A , Kozai Takashi D Y
Published: March 2022

Objective. Neural prosthetics often use intracortical microstimulation (ICMS) for sensory restoration. To restore natural and functional feedback, we must first understand how stimulation parameters influence the recruitment of neural populations. ICMS waveform asymmetry modulates the spatial activation of neurons around an electrode at 10 Hz; however, it is unclear how asymmetry may differentially modulate population activity at frequencies typically employed in the clinic (e.g. 100 Hz). We hypothesized that stimulation waveform asymmetry would differentially modulate preferential activation of certain neural populations, and the differential population activity would be frequency-dependent. Approach. We quantified how asymmetric stimulation waveforms delivered at 10 or 100 Hz for 30 s modulated spatiotemporal activity of cortical layer II/III pyramidal neurons using in vivo two-photon and mesoscale calcium imaging in anesthetized mice. Asymmetry is defined in terms of the ratio of the duration of the leading phase to the duration of the return phase of charge-balanced cathodal- and anodal-first waveforms (i.e. longer leading phase relative to return has larger asymmetry). Main results. Neurons within 40–60 µm of the electrode display stable stimulation-induced activity indicative of direct activation, which was independent of waveform asymmetry. The stability of 72% of activated neurons and the preferential activation of 20%–90% of neurons depended on waveform asymmetry. Additionally, this asymmetry-dependent activation of different neural populations was associated with differential progression of population activity. Specifically, neural activity tended to increase over time during 10 Hz stimulation for some waveforms, whereas activity remained at the same level throughout stimulation for other waveforms. During 100 Hz stimulation, neural activity decreased over time for all waveforms, but decreased more for the waveforms that resulted in increasing neural activity during 10 Hz stimulation. Significance. These data demonstrate that at frequencies commonly used for sensory restoration, stimulation waveform alters the pattern of activation of different but overlapping populations of excitatory neurons. The impact of these waveform specific responses on the activation of different subtypes of neurons as well as sensory perception merits further investigation.
Reaching the superscattering regime with BIC physics
Authors: Canós Valero Adrià , Shamkhi Hadi K. , Kupriianov Anton S. , Tuz Vladimir R. , Bobrovs Vjaceslavs , Kivshar Yuri S. , Shalin Alexander S.
Published: March 2022

We uncover a novel mechanism of superscattering from subwavelength resonators linked to the physics of bound states in the continuum (BICs). Enhanced scattering occurs due to constructive interference within the Friedrich-Wintgen mechanism of interfering resonances. Through this process, the scattering cross section of a single resonance can exceed the currently established limit. We develop a general non-Hermitian model to describe interfering resonances of quasi-normal modes, and study subwavelength dielectric nonspherical resonators exhibiting avoided crossing resonances and quasi-BIC states. Our results reveal novel physics of non-Hermitian systems suggesting important applications for metadevices.
Comment on ‘From the Paris Agreement to corporate climate commitments: evaluation of seven methods for setting “science-based” emission targets’
Authors: Chang Andres , Farsan Alexander , Carrillo Pineda Alberto , Cummis Cynthia , Weber Chris
Published: March 2022

A study from Bjørn et al (2021) suggests that methods to allocate emissions to companies proportionally to their economic growth are consistent with equity-related principles and are effective at conserving a global emissions budget while the science based targets initiative’s (SBTi’s) absolute contraction approach (ACA) fulfills neither qualification. Here we identify four areas of concern with the study and propose a more comprehensive approach to science based targets (SBT) method evaluation. We respond that first, the authors’ method characterization does not differentiate between the emissions allocation that occurs in mitigation scenarios and that which is normatively caused by method formulae, and it misinterprets the drivers of emissions allocation in scenarios. Second, we note that the authors evaluate a method formula for ACA that does not match its use by the SBTi. Third, we acknowledge that allocating emissions based on economic growth can yield incoherent results by comparison to published climate change mitigation scenarios and suggest the authors also evaluate whether methods are effective at conserving sub-global emissions budgets. Fourth, we observe that although the study is framed as an evaluation of SBT methods, it relies almost entirely on assessments of one characteristic. We conclude by proposing a set of principles that should be met by effective SBT methods and a high-level assessment of SBT methods against these principles.
Reply to Comment on ‘From the Paris Agreement to corporate climate commitments: evaluation of seven methods for setting “science-based” emission targets’
Authors: Bjørn Anders , Lloyd Shannon , Matthews Damon
Published: March 2022

The Science Based Targets initiative has published a Comment to our study (Bjørn et al 2021 Environ. Res. Lett.
16 054019). We see the Comment as an important step towards addressing our study’s call for more systematic presentation of methods for setting science-based targets and increased transparency behind the initiative’s method recommendations. We also agree with some of the Comment’s points of criticism of our study and the related nuances introduced. Yet, we find other points to be inaccurate or misdirected. Here, we reply to the Comment by clarifying misunderstandings on our study’s aims, providing additional methodological details, and elaborating on our perspectives.
Self-thinning forest understoreys reduce wildfire risk, even in a warming climate
Authors: Zylstra Philip J , Bradshaw S Don , Lindenmayer David B
Published: March 2022

As climatic changes continue to drive increases in the frequency and severity of forest fires, it is critical to understand all of the factors influencing the risk of forest fire. Using a spatial dataset of areas burnt over a 65 year period in a 528 343 ha study area, we examined three possible drivers of flammability dynamics. These were: that forests became more flammable as fine biomass (fuel) returned following disturbance (H1), that disturbance increased flammability by initiating dense understorey growth that later self-thinned (H2), and that climatic effects were more important than either of these internal dynamics (H3). We found that forests were unlikely to burn for a short ‘young’ period (5–7 years) following fire, very likely to burn as the regrowing understorey became taller and denser (regrowth period), then after a total post-disturbance period of 43–56 years (young + regrowth periods), fire became unlikely and continued to decrease in likelihood (mature period). This trend did not change as the climate warmed, although increases in synoptic variability (mean changes in synoptic systems per season) had a pronounced effect on wildfire likelihood overall. Young forest and regrowth forest became increasingly likely to burn in years of greater synoptic variability and the time taken for forests to mature increased, but in years with the most severe synoptic variability, mature forests were the least likely to burn. Our findings offer an explanation for fire behaviour in numerous long-term studies in diverse forest types globally and indicate that, even in the face of a warming climate, ‘ecologically-cooperative’ approaches may be employed that reinforce rather than disrupt natural ecological controls on forest fire. These range from traditional indigenous fire knowledge, to modern targeting of suppression resources to capitalise on the benefits of self-thinning, and minimise the extent of dense regrowth in the landscape.