bluuebunny/crossref_metadata_2025 huggingface dataset:
Total Synthesis of 4α-Hydroxyallosecurinine and Securingine F, Securinega Alkaloids with a C4-Hydroxy Handle for Biofunctional Derivatizations
Authors: Han Sunkyu , Park Sangbin , Kim Doyoung , Yang Wooil
Published: March 2023

We describe the first total synthesis of the C4-hydroxylated securinega alkaloids 4α-hydroxyallosecurinine and securingine F. The synthetic route features an Ellman’s light-mediated hydrogen-atom-transfer-based epimerization reaction that effectively sets the desired configuration at the C2 position. Simultaneous skeletal rearrangement from neosecurinane to securinane frameworks and stereochemical reversal at the C4 site was achieved under Mitsunobu reaction conditions. The C4-hydroxy group is envisioned to serve as a handle for potential biofunctional derivatizations.
Qi Field Effect of Acupuncture Time-Acupoints-Space in the Treatment of Long Coronavirus Disease and Coronavirus Disease 2019 Vaccine Adverse Reactions
Authors: Zhu Miansheng
Published: March 2023

Corona Virus disease 2019 (COVID-19) has become a serious challenge. On the one hand, there is not a single explanation of its pathological mechanism, which directly affects the treatment efficacy. On the other hand, the complicated symptoms of long COVID and COVID-19 vaccine adverse reactions involve multiple systems and the number of affected patients is large, which have attracted great attention. Acupuncture time-acupoints-space (ATAS) is a new acupuncture technique developed on the basis of four methods of day-prescription of acupoints (Na Jia method), hour-prescription of acupoints (Na Zi Method), eightfold methods of the sacred tortoise (Ling Gui Eight Methods), and eight methods of swift puncturing of needles (Fei Teng Eight Methods) in midnight-noon and ebb-flow doctrine (Zi Wu Liu Zhu). The main idea of ATAS is to use the orderly combination of time acupoints and space acupoints to construct a field to regulate qi movement and treat diseases through the qi field effect. In France, although traditional Chinese medicine cannot be directly used to treat COVID-19, hundreds of patients with long COVID and COVID-19 vaccine adverse reactions have been treated using the four methods of ATAS. With reference to the microcirculatory lesions in the pathological mechanism of COVID-19 in Western medicine, hour prescription of acupoints (Na Zi Method) of ATAS showed specific efficacy for long COVID.
Redesigning Care for the Management of Postpartum Hypertension: How Can Ob–Gyns and Primary Care Physicians Partner in Caring for Patients after a Hypertensive Pregnancy?
Authors: Berhie Saba H. , Little Sarah E. , Shulkin Jay , Seely Ellen W. , Nour Nawal M. , Wilkins-Haug Louise
Published: March 2023

The standard care model in the postpartum period is ripe for disruption and attention. Hypertensive disorders of pregnancy (HDPs) can continue to be a challenge for the postpartum person in the immediate postpartum period and is a harbinger of future health risks. The current care approach is inadequate to address the needs of these women. We propose a model for a multidisciplinary clinic and collaboration between internal medicine specialists and obstetric specialists to shepherd patients through this high-risk time and provide a bridge for lifelong care to mitigate the risks of a HDP.

Key Points
High-pressure studies of atomically thin van der Waals materials
Authors: Pimenta Martins Luiz G. , Comin Riccardo , Matos Matheus J. S. , Mazzoni Mário S. C. , Neves Bernardo R. A. , Yankowitz Matthew
Published: March 2023

Two-dimensional (2D) materials and their moiré superlattices represent a new frontier for quantum matter research due to the emergent properties associated with their reduced dimensionality and extreme tunability. The properties of these atomically thin van der Waals (vdW) materials have been extensively studied by tuning a number of external parameters such as temperature, electrostatic doping, magnetic field, and strain. However, so far pressure has been an under-explored tuning parameter in studies of these systems. The relative scarcity of high-pressure studies of atomically thin materials reflects the challenging nature of these experiments, but, concurrently, presents exciting opportunities for discovering a plethora of unexplored new phenomena. Here, we review ongoing efforts to study atomically thin vdW materials and heterostructures using a variety of high-pressure techniques, including diamond anvil cells, piston cylinder cells, and local scanning probes. We further address issues unique to 2D materials such as the influence of the substrate and the pressure medium and overview efforts to theoretically model the application of pressure in atomically thin materials.
The deterministic excitation paradigm and the late Pleistocene glacial terminations
Authors: Pierini Stefano
Published: March 2023

A deterministic excitation (DE) paradigm is formulated, according to which the abrupt late Pleistocene glacial terminations correspond to the excitation, by the orbital forcing, of nonlinear relaxation oscillations (ROs) internal to the climate system in the absence of any stochastic parameterization. Specific rules are derived from the DE paradigm: they parameterize internal climate feedbacks, which, when activated by the crossing of certain tipping points, excite a RO. Such rules are then applied to the output of an energy-balance model simulating the fluctuations induced by realistic orbital forcing on the glacial state. The timing of the glacial terminations, thus, obtained in a reference simulation is found to be in good agreement with proxy records. A sensitivity analysis insures the robustness of the timing. The potential irrelevance of noise allowing DE to hold is discussed, and a possible explanation of the 100-kyr cycle problem based on DE is outlined. In conclusion, the DE paradigm provides the simplest possible dynamical systems characterization of the link between orbital forcing and glacial terminations implied by the Milankovitch hypothesis.
Inferring interaction domains of collectively moving agents with varying radius of influence
Authors: Basak Udoy S. , Islam Md Ekramul , Sattari Sulimon
Published: March 2023

Transfer entropy (TE) has proven to be an effective tool for determining the causal connection between two processes. For example, TE has been used to classify leader and follower agents in collective dynamics in the Vicsek model (VM). However, previous results have limited interaction radii, which are precisely the same among all agents, which is not realistic in practice. Here, we propose a modified version of the VM where the domains in which an agent can be influenced by others vary from agent-to-agent, which matches more closely with a real-life setting where not all agents have the same physical traits. We demonstrate that the TE vs cut-off technique is robust and efficacious in determining the maximum distance at which two interacting agents can transfer information in the system. We find that for two agents with different interaction domains, the derivative of the average inward TE can determine the individual agent’s interaction domain. In a system with numerous agents, the TE vs cut-off technique is shown to be effective in predicting the average interaction domain of all agents, where the interaction domain of each agent was randomly selected from a Gaussian distribution.
On the cylinder noise and drag reductions in different Reynolds number ranges using surface pattern fabrics
Authors: Zheng Chuntai , Zhou Peng , Zhong Siyang , Zhang Xin
Published: March 2023

This study experimentally investigates the potential of using surface pattern fabrics for the cylinder noise and drag control in different Reynolds number ranges. The aerodynamic and aeroacoustic effects were evaluated through the noise and force measurements in an anechoic wind tunnel. It was observed that the noise and drag reductions take place simultaneously but in different Reynolds number ranges, corresponding to the cylinder flow in different flow regimes, e.g., sub-critical, critical, and supercritical flow regimes. Microphone arc array measurements reveal that the suppression of the Aeolian tone in the critical regime is the major cause of noise reductions, and the noise directivity gradually loses dipole features in the critical and supercritical flow regimes, which is probably related to the reduced lift fluctuation coefficient and the spanwise segment of the sound sources. Further hotwire wake survey revealed significant changes in flow dynamics, which explain the variations of noise and drag in different flow regimes. We have shown for the first time that fabric with different surface patterns can effectively reduce cylinder drag and noise in different Reynolds number ranges. Since the Reynolds number is a key factor that determines the flow state in practical engineering applications, e.g., cycling aerodynamics, this study suggests that optimal drag and noise reductions can be realized by employing the combinations of different surface pattern fabrics to account for the Reynolds number effects.
Directly revealing the electrical annealing of nanoscale conductive networks with solid spins
Authors: Wang En-Hui , Chen Xiang-Dong , Shan Long-Kun , Zang Han-Xiang , Guo Guang-Can , Sun Fang-Wen
Published: March 2023

Complex electrical structures composed of nanomaterials are widely studied in the research of nanoelectronics. Characterizing the current distribution is important to understand the current conducting mechanism and optimize the device's design. In this work, we employed the nitrogen vacancy centers in diamond as quantum sensors to directly and noninvasively monitor currents in nanowire networks. The sub-micrometer magnetic field imaging was achieved by injecting microwave current into networks and detecting the magnetic resonate spins' population, revealing the internal current paths involved in electrical conduction during electrical annealing. The establishment, breakdown, and reform of current paths were imaged in detail, which are difficult to realize through conventional methods. The mechanism of resistance change and relocating of current pathways was subsequently analyzed. This work demonstrates that a diamond-based quantum microscope is a useful tool to unveil the nanoscale conducting properties of complex conductive networks and guide the design for potential applications.
Controlled movement of lower strike points by applying a divertor coil on the EAST tokamak
Authors: Gong C. C. , Shao L. M. , Xu G. S. , Zhang Y. , Qiu Q. L. , Wang Z. L. , Wu Y. B. , Yuan Q. P.
Published: March 2023

A new in-vessel water-cooled coil has been placed below the lower tungsten-covered divertor in EAST, aiming at moving the strike points in the divertor and spreading the heat flow on the targets. To achieve controlled movement of the strike points by the plasma control system (PCS) when applying the in-vessel coil, the plasma equilibrium configurations are predicted by the tokamak equilibrium (TEQ) code. The divertor coil current is involved in these calculations. The shape control parameters in the PCS are adjusted according to the predesigned equilibria from the TEQ code. The strike point movement over a wide range has been achieved in the experiment while keeping the main plasma stable. Thus, this method for divertor strike point movement with the assistance of the divertor coil is feasible.
Unraveling the charge transfer variation of tetrathiafulvalene-based organic crystals through fragment charge difference calculation
Authors: Mu Yakui , Wang Tan , Deng Zeyu , Chan Bun , Wang Tiesheng
Published: March 2023

Organic crystals assembled by a well-established family of electron donors, tetrathiafulvalene (TTF)-based molecules, hold great potential for electronics, smart materials, and superconductors. Combining with Marcus' theory and first-principles calculations, we have adopted a fragment charge difference (FCD) method to investigate the charge transfer properties of the TTF-based crystals. Our FCD predictions are highly consistent with those obtained from a well-accepted site energy correction method. We have demonstrated the significant influence of both structure and chemistry on the charge transfer properties using polymorphs, i.e., α-phase tetrathiafulvalene (1) versus β-phase tetrathiafulvalene (2), and crystals with homologous molecular packings, i.e., 1 versus dithiophene-TTF (3). We have also introduced multiple factors to provide further insights into the variation in charge transfer properties of the TTF-based crystals, including energy gap (∆E), centroid distance (ri), orbital distribution correction factor (Hs), and reorganization energy (λ). By taking advantage of our analysis, we have rationalized high mobility in hexamethylene-TTF (4) and low mobility in bis(ethylenedithio)-TTF (5). Our multiple-factor evaluation could support an approach to designing electrically conducting TTF-based materials and provide a method to estimate charge transfer properties effectively.
2D-IR spectroscopy of carbohydrates: Characterization of thiocyanate-labeled β-glucose in CHCl3 and H2O
Authors: Gasse P. , Stensitzki T. , Mai-Linde Y. , Linker T. , Müller-Werkmeister H. M.
Published: March 2023

Carbohydrates constitute one of the four key classes of biomacromolecules but have not been studied by 2D-IR spectroscopy so far. Similarly as for proteins, a lack of native vibrational reporter groups, combined with their huge structural diversity, leads to spectrally congested infrared spectra already for single carbohydrates. Biophysical studies are further impeded by the strong overlap between water modes and carbohydrate modes. Here, we demonstrate the application of the known vibrational reporter group thiocyanate (SCN) as a label in glucose. In this first study, we are able to perform IR and 2D-IR spectroscopy of β-glucose with SCN at the C2 position in chloroform. Upon improved synthesis and the removal of all protecting groups, we successfully performed 2D-IR spectroscopy of β-glucose in H2O. All experimental results are compared to those of methyl-thiocyanate as a reference sample. Overall, we show that the concept of using site-specific vibrational reporter groups can be transferred to carbohydrates. Thus, biophysical studies with 2D-IR spectroscopy can now expand to glycoscience.
Characteristics of micro-discharge process in saline solution with pin-to-pin electrodes driven by a low-voltage high-frequency AC power supply
Authors: Sun Ming-Yang , Xu Gui-Min , Zhang Guan-Jun
Published: March 2023

Low-temperature plasma ablation has been clinically used in minimally invasive surgeries. However, there is still a lack of research on its discharge process and ablation mechanism. This paper investigates the bubble generation process and micro-discharge phenomena of pin-to-pin surgical electrodes in NaCl solution driven by a high-frequency AC power supply at a level of (100–150) V. Microbubbles will occur around electrodes and merge to form a vapor layer that can completely cover the electrodes. Then, micro-discharges in the form of microspark would occur around the grounded electrode. The effects of geometrical and electrical parameters on the generation of vapor layers and micro-discharges are analyzed by the statistical results. It is found that the conductivity of the solution has an important influence on the generation probability and stability of vapor layers together with the occurrence position of micro-discharges. The simulation results of the discharge process and the experimental results match well with each other, and they demonstrate jointly that the discharge process is mainly influenced by the electrolytic effect.
High quality quasi-two-dimensional organic–inorganic hybrid halide perovskite film for high performance photodetector
Authors: Xian Siyi , Hou Sumin , Zhang Huafang , Yang Jiazhen , Pan Gencai , Gao Huiping , You Wenwu , Zhang Zhenlong , Zhu Baohua , Mao Yanli
Published: March 2023

Two-dimensional (2D) Ruddlesden–Popper perovskites have attracted extensive attention in photodetectors (PDs) due to their exceptional optoelectronic properties. The performances of PDs show extremely strong dependence on defects in 2D perovskites. Herein, high quality and less defective BA2FAPb2I7 perovskite films were obtained by a simple one-step spin coating method with rare earth doping assisted crystal growth. Furthermore, BA2FAPb2I7 perovskite films were used as photoresponsive materials to fabricate architectural simplicity photoconductor PDs. Under 405 nm laser illumination, the PDs show remarkable balance detect properties with a low dark current of 5.1 × 10−11 A, a large on/off ratio of 2.2 × 105, a high responsivity (R) of 4.51 A/W, an outstanding detectivity Dshot* of 4.31 × 1013 Jones, and a response speed of 80 μs/76 μs. The R and Dshot* of the PDs are outstanding in the reported quasi-2D perovskite PDs with the same structure. Our work not only paves an indubitably feasible way for fabrication of quasi-2D perovskite PDs via improving their natural material properties but also provides a clear direction for further enhancing the performance of other perovskites optoelectronics.
Theoretical adjustment of metalorganic chemical vapor deposition process parameters for high-quality gallium nitride epitaxial films
Authors: Wang Dong , Lao Junyan , Xiao Wenjia , Qu Hengxu , Wang Jie , Wang Gang , Li Jian
Published: March 2023

Semiconductor thin films for electronic devices are usually produced through processes such as chemical vapor deposition, which requires careful control of the gas flow, heat distribution, and concentration distribution over the substrate to ensure a uniform deposition rate and thickness. Herein, a systematic method is proposed for the theoretical adjustment of metalorganic chemical vapor deposition (MOCVD) process parameters. To this end, a GaN-MOCVD reactor with a vertical injection structure was simulated based on computational fluid dynamics to analyze the stable flow under a fixed flow rate. The orthogonal experimental design was used to analyze the influence of process conditions on film quality. A neural network and genetic algorithm were used to optimize the inlet flow under the stable flow state to render the coefficient of variation <3%. Under these conditions, the flow field in the reactor was stabilized to ensure a uniform thickness for the deposited film. This study provides not only an effective solution for high-quality epitaxial growth but also a theoretical basis for subsequent experiments and equipment improvement.
Effect of mechanical properties of red blood cells on their equilibrium states in microchannels
Authors: Wang Xiaolong , Ii Satoshi , Sugiyama Kazuyasu , Noda Shigeho , Jing Peng , Liu Deyun , Che XiaJing , Gong Xiaobo
Published: March 2023

The equilibrium positions of red blood cells (RBCs) and their steady motions in microchannel affect the hemodynamics in vivo and microfluidic applications on a cellular scale. However, the dynamic behavior of a single RBC in three-dimensional cylindrical microchannels still needs to be classified systematically. Here, with an immersed boundary method, the phase diagrams of the profiles and positions of RBCs under equilibrium states are illustrated in a wide range of Capillary numbers. The effects of initial positions are explored as well. Numerical results present that the profiles of RBCs at equilibrium states transform from snaking, tumbling to slipper, or parachute with the increase in flow rates, and whether RBCs finally approach slipper or parachute motion under large shear rates is dependent on their initial positions. With the increase in tube diameters, the equilibrium positions of RBCs are closer to tube walls relatively. Although both the increase in membrane shear modulus and the viscosity ratio are regarded as the stiffening of RBCs, the change of membrane property does not affect the dependence of the profiles and positions of RBCs at equilibrium states on the shear rates of the flow obviously, but with the increase in viscosity ratio, RBCs move further away from the centerline of the tube associating with more asymmetric characteristics in their stable profiles. The present results not only contribute to a better understanding of the dynamic behavior and multiple profiles of single RBC in microcirculation, but also provide fundamentals in a large range of Capillary numbers for cell sorting with microfluidic devices.
One-channel time reversal focusing of ultra-high frequency acoustic waves on a MEMS
Authors: Dahmani H. , Smagin N. , Campistron P. , Carlier J. , Toubal M. , Nongaillard B.
Published: March 2023

This Letter reports on a work performed to fabricate and characterize a silicon micro-machined cavity dedicated to micro-resolution Ultra-High Frequency imaging in microfluidics and microbiological applications using one-channel time reversal. Time reversal provides the means to spatially and temporally localize elastic energy on a receiver. Here, the arrays of zinc oxide micro transducers are coupled with a 400 μm thick silicon wafer containing micromachined structures for acoustical field confinement. Characterization of the diffused acoustic field and time-reversal retro-focusing are reported. The transducers are wideband in the 0.2–2 GHz range with a central frequency of 0.9 GHz.
An investigation of the flow structure beneath solitary waves with constant vorticity on a conducting fluid under normal electric fields
Authors: Flamarion M. V. , Gao T. , Ribeiro-Jr R.
Published: March 2023

The motion of an interface separating two fluids under the effect of electric fields is a subject that has picked the attention of researchers from different areas. While there is an abundance of studies investigating the free surface wave properties, very few works have examined the associated velocity field within the bulk of the fluid. Therefore, in this paper, we investigate numerically the flow structure beneath solitary waves with constant vorticity on an inviscid conducting fluid bounded above by a dielectric gas under normal electric fields in the framework of a weakly nonlinear theory. Elevation and depression solitary waves with constant vorticity are computed by a pseudo-spectral method, and a parameter sweep on the intensity of the electric field is carried out to study its role in the appearance of stagnation points. We find that for elevation solitary waves, the location of stagnation points does not change significantly with a variation of the electric field. For depression solitary waves, on the other hand, the electric field acts as a catalyzer that makes possible the appearance of stagnation points. In the sense that in its absence, there are no stagnation points.
A simplified model for the impact of dielectric polarization of a charged droplet on its diffusiophoresis
Authors: Majhi Subrata , Bhattacharyya Somnath
Published: March 2023

This study aims to quantify the impact of the dielectric permittivity of a droplet on its diffusiophoresis in different types of electrolytes. The dielectric droplet polarizes by the diffusion field along with the local electric field created by the interactions of the double layer with the imposed ionic concentration gradient, which generates an induced surface charge density anti-symmetrically distributed on the droplet surface. This induced surface charge influences both electrophoresis and chemiphoresis parts. Based on a low imposed concentration gradient, a simplified model is derived through a first-order perturbation technique. Dielectric polarization of the droplet attenuates the spinning force at the interface. This creates the mobility of a droplet of higher dielectric permittivity in the presence of a stronger diffusion field significantly higher than that of a perfectly dielectric droplet, and its value depends on the polarity of the droplet surface charge. In the absence of the diffusion field, the mobility of a conducting droplet remains a positive immaterial of the polarity of its surface charge density. We find that the impact of the dielectric polarization becomes significant as the surface charge density increases and attenuates with the increase in droplet viscosity. For a dielectric droplet at a thinner Debye length, a step-jump in mobility occurs at a higher value of the surface charge density. Such a type of step-jump in mobility does not appear for the conducting droplet due to the absence of the Maxwell stress at the interface.
Analysis two types of K complexes on the human EEG based on classical continuous wavelet transform
Authors: Dorokhov V. B. , Runnova A. , Tkachenko O. N. , Taranov A. O. , Arseniev G. N. , Kiselev A. , Selskii A. , Orlova A. , Zhuravlev M.
Published: March 2023

In our work, we compare EEG time–frequency features for two types of K-complexes detected in volunteers performing the monotonous psychomotor test with their eyes closed. Type I K-complexes preceded spontaneous awakenings, while after type II K-complexes, subjects continued to sleep at least for 10 s after. The total number of K-complexes in the group of 18 volunteers was 646, of which of which type I K-complexes was 150 and type II K-complexes was 496. Time–frequency analysis was performed using continuous wavelet transform. EEG wavelet spectral power was averaged upon several brain zones for each of the classical frequency ranges (slow wave, δ, θ, α, β1, β2, γ bands). The low-frequency oscillatory activity (δ-band) preceding type I K-complexes was asymmetrical and most prominent in the left hemisphere. Statistically significant differences were obtained by averaging over the left and right hemispheres, as well as projections of the motor area of the brain, p<0.05. The maximal differences between the types I and II of K-complexes were demonstrated in δ-, θ-bands in the occipital and posterior temporal regions. The high amplitude of the motor cortex projection response in β2-band, [20;30] Hz, related to the sensory-motor modality of task in monotonous psychomotor test. The δ-oscillatory activity preceding type I K-complexes was asymmetrical and most prominent in the left hemisphere may be due to the important role of the left hemisphere in spontaneous awakening from sleep during monotonous work, which is an interesting issue for future research.
Effect of a streamwise vortex on supersonic boundary layer transition
Authors: Wei Feng , Zhao Yu-Xin , Liu Wei-Dong , Wang Qian-Cheng , Yang Rui
Published: March 2023

Supersonic boundary layer transition induced by a streamwise vortex is experimentally investigated based on the nanoparticle-based planar laser scattering technology, with an inflow Mach number of 2.7 and a unit Reynolds number of 8.79 × 106 m−1. Though the vortex is outside the boundary layer, it results in obvious difference of transition position along spanwise direction. On the up-wash side, transition to turbulence is completed in advance compared to the vortex-free case, and transition position moves more upstream as the vortex approaches the wall. Conversely, the transition process on down-wash side is inhibited. The promotion and inhibition effects on transition are found to be induced by the influence of vortex on streak density.
Electrically tunable Gilbert damping in van der Waals heterostructures of two-dimensional ferromagnetic metals and ferroelectrics
Authors: Qiu Liang , Wang Zequan , Ni Xiao-Sheng , Yao Dao-Xin , Hou Yusheng
Published: March 2023

Tuning the Gilbert damping of ferromagnetic (FM) metals via a nonvolatile way is of importance to exploit and design next-generation novel spintronic devices. Through systematical first-principles calculations, we study the magnetic properties of the van der Waals heterostructure of two-dimensional FM metal CrTe2 and ferroelectric (FE) In2Te3 monolayers. The ferromagnetism of CrTe2 is maintained in CrTe2/In2Te3 and its magnetic easy axis can be switched from in-plane to out-of-plane by reversing the FE polarization of In2Te3. Excitingly, we find that the Gilbert damping of CrTe2 is tunable when the FE polarization of In2Te3 is reversed from upward to downward. By analyzing the k-dependent contributions to the Gilbert damping, we unravel that such tunability results from the changed intersections between the bands of CrTe2 and Fermi level on the reversal of the FE polarizations of In2Te3 in CrTe2/In2Te3. Our work provides an appealing way to electrically tailor Gilbert dampings of two-dimensional FM metals by contacting them with ferroelectrics.
The surface states of transition metal X-ides under electrocatalytic conditions
Authors: Liu Heng , Jia Xue , Cao Ang , Wei Li , D’agostino Carmine , Li Hao
Published: March 2023

Due to conversion equilibrium between solvent and H- and O-containing adsorbates, the true surface state of a catalyst under a particular electrochemical condition is often overlooked in electrocatalysis research. Herein, by using surface Pourbaix analysis, we show that many electrocatalytically active transition metal X-ides (e.g., oxides, nitrides, carbides, and hydroxides) tend to possess the surface states different from their pristine stoichiometric forms under the pH and potential of interest due to water dissociation or generation. Summarizing the density functional theory calculated surface Pourbaix diagrams of 14 conditionally stable transition metal X-ide materials, we found that some of these surfaces tend to be covered by O-containing adsorbates at a moderate or high potential, while vacancies or H-covered surfaces may form at a low potential. These results suggest the possibility of poisoning or creation of surface sites beyond the pristine surface, implying that the surface state under reaction conditions (pH and potentials) needs to be considered before the identification and analysis of active sites of a transition metal X-ide catalyst. In addition, we provide an explanation of the observed theory and experiment discrepancy that some transition metal X-ides are “more stable in experiment than in theory.” Based on our findings, we conclude that analyzing the surface state of transition metal X-ide electrocatalysts by theoretical calculations (e.g., surface Pourbaix diagram analysis), in situ/operando and post-reaction experiments are indispensable to accurately understand the underlying catalytic mechanisms.
Microbiology in sustainable remediation of contaminated sites
Authors: Lee Matthew , Manefield Mike
Published: March 2023

The release of chemicals that have negative human or environmental health impacts has been rife around the world for a century. Approaches to contaminated site remediation have evolved over this time to address environmental contamination. Over the past 15 years there has been an increasing focus on sustainability in remediation. Bioremediation has emerged as a remediation technology of choice based on sustainability credentials. Research on pollutant biodegradation, including the discovery and characterisation of microbes responsible, underpins biological remediation applications.
Facing our plastic waste crisis: biorecycling as a promising solution
Authors: Peng Yi , Prabhu Apoorva , Rinke Chris
Published: March 2023

We are in a global plastic waste crisis. Plastic production has steadily increased over the last half century, while recycling rates remain as low as 9% in some nations, including Australia. Most plastic waste ends up in landfill or the environment as a lost resource, triggering the production of more virgin plastic to satisfy demands. Shifting away from this wasteful, linear economy towards a circular economy, where waste products are treated as a valuable resource and are recycled, will require considerable innovative advancements to our current plastic recycling methods. Biological recycling (biorecycling) has emerged as a promising solution, with several advantages over mechanical and chemical recycling. Using enzymatic reactions, long plastic polymers are cut into monomers without the need for high temperatures or chemical catalysts, and without affecting product quality. Biorecycling allows sustainable, commercially viable and near-infinite recycling of synthetic polymers. In this paper, we discuss reasons for our current plastic waste crisis, compare plastic recycling methods with a focus on biorecycling and explore commercial ventures of enzyme-based recycling technologies. We present recent developments in enzyme discovery, enzyme characterisations and protein engineering. Finally, we propose a strategy to move towards a circular plastic economy, by embracing biorecycling.
The book of Lambda does not tell us that naturally occurring lysogens of
Escherichia coli
are likely to be resistant as well as immune
Authors: Berryhill Brandon A. , Garcia Rodrigo , McCall Ingrid C. , Manuel Joshua A. , Chaudhry Waqas , Petit Marie-Agnès , Levin Bruce R.
Published: March 2023

The most significant difference between bacteriophages functionally and ecologically is whether they are purely lytic (virulent) or temperate. Virulent phages can only be transmitted horizontally by infection, most commonly with the death of their hosts. Temperate phages can also be transmitted horizontally, but upon infection of susceptible bacteria, their genomes can be incorporated into that of their host’s as a prophage and be transmitted vertically in the course of cell division by their lysogenic hosts. From what we know from studies with the temperate phage Lambda and other temperate phages, in laboratory culture, lysogenic bacteria are protected from killing by the phage coded for by their prophage by immunity; where upon infecting lysogens, the free temperate phage coded by their prophage is lost. Why are lysogens not also resistant as well as immune to the phage coded by their prophage since immunity does not confer protection against virulent phages? To address this question, we used a mathematical model and performed experiments with temperate and virulent mutants of the phage Lambda in laboratory culture. Our models predict and experiments confirm that selection would favor the evolution of resistant and immune lysogens, particularly if the environment includes virulent phage that shares the same receptors as the temperate. To explore the validity and generality of this prediction, we examined 10 lysogenic
Escherichia coli
from natural populations. All 10 were capable of forming immune lysogens, but their original hosts were resistant to the phage coded by their prophage.
Altered DNA repair pathway engagement by engineered CRISPR-Cas9 nucleases
Authors: Chauhan Vikash P. , Sharp Phillip A. , Langer Robert
Published: March 2023

CRISPR-Cas9 introduces targeted DNA breaks that engage competing DNA repair pathways, producing a spectrum of imprecise insertion/deletion mutations (indels) and precise templated mutations (precise edits). The relative frequencies of these pathways are thought to primarily depend on genomic sequence and cell state contexts, limiting control over mutational outcomes. Here, we report that engineered Cas9 nucleases that create different DNA break structures engage competing repair pathways at dramatically altered frequencies. We accordingly designed a Cas9 variant (vCas9) that produces breaks which suppress otherwise dominant nonhomologous end-joining (NHEJ) repair. Instead, breaks created by vCas9 are predominantly repaired by pathways utilizing homologous sequences, specifically microhomology-mediated end-joining (MMEJ) and homology-directed repair (HDR). Consequently, vCas9 enables efficient precise editing through HDR or MMEJ while suppressing indels caused by NHEJ in dividing and nondividing cells. These findings establish a paradigm of targeted nucleases custom-designed for specific mutational applications.
Responding to Questions at Press Conferences
Authors: Wu Peng
Published: March 2023

Responding to Questions at Press Conferences makes clear how the spokespersons at China’s diplomatic press conferences maneuver strategically in defining the issues in the empirical counterpart of the confrontation stage when responding to the journalists’ questions and how this confrontational maneuvering is meant to be instrumental in convincing the intended audience. The detailed and systematic analysis of the various modes of confrontational maneuvering adopted by the spokespersons elucidate how China’s recently established “progressive” diplomatic style is shaped by its spokespersons’ argumentative discourse.
Deep learning techniques and mathematical modeling allow 3D analysis of mitotic spindle dynamics
Authors: Dang David , Efstathiou Christoforos , Sun Dijue , Yue Haoran , Sastry Nishanth R. , Draviam Viji M.
Published: March 2023

Time-lapse microscopy movies have transformed the study of subcellular dynamics. However, manual analysis of movies can introduce bias and variability, obscuring important insights. While automation can overcome such limitations, spatial and temporal discontinuities in time-lapse movies render methods such as 3D object segmentation and tracking difficult. Here, we present SpinX, a framework for reconstructing gaps between successive image frames by combining deep learning and mathematical object modeling. By incorporating expert feedback through selective annotations, SpinX identifies subcellular structures, despite confounding neighbor-cell information, non-uniform illumination, and variable fluorophore marker intensities. The automation and continuity introduced here allows the precise 3D tracking and analysis of spindle movements with respect to the cell cortex for the first time. We demonstrate the utility of SpinX using distinct spindle markers, cell lines, microscopes, and drug treatments. In summary, SpinX provides an exciting opportunity to study spindle dynamics in a sophisticated way, creating a framework for step changes in studies using time-lapse microscopy.
ExTrack characterizes transition kinetics and diffusion in noisy single-particle tracks
Authors: Simon François , Tinevez Jean-Yves , van Teeffelen Sven
Published: March 2023

Single-particle tracking microscopy is a powerful technique to investigate how proteins dynamically interact with their environment in live cells. However, the analysis of tracks is confounded by noisy molecule localization, short tracks, and rapid transitions between different motion states, notably between immobile and diffusive states. Here, we propose a probabilistic method termed ExTrack that uses the full spatio-temporal information of tracks to extract global model parameters, to calculate state probabilities at every time point, to reveal distributions of state durations, and to refine the positions of bound molecules. ExTrack works for a wide range of diffusion coefficients and transition rates, even if experimental data deviate from model assumptions. We demonstrate its capacity by applying it to slowly diffusing and rapidly transitioning bacterial envelope proteins. ExTrack greatly increases the regime of computationally analyzable noisy single-particle tracks. The ExTrack package is available in ImageJ and Python.
TLN1 contains a cancer-associated cassette exon that alters talin-1 mechanosensitivity
Authors: Gallego-Paez Lina M. , Edwards William J.S. , Chanduri Manasa , Guo Yanyu , Koorman Thijs , Lee Chieh-Yu , Grexa Nina , Derksen Patrick , Yan Jie , Schwartz Martin A. , Mauer Jan , Goult Benjamin Thomas
Published: March 2023

Talin-1 is the core mechanosensitive adapter protein linking integrins to the cytoskeleton. The TLN1 gene is comprised of 57 exons that encode the 2,541 amino acid TLN1 protein. TLN1 was previously considered to be expressed as a single isoform. However, through differential pre-mRNA splicing analysis, we discovered a cancer-enriched, non-annotated 51-nucleotide exon in TLN1 between exons 17 and 18, which we refer to as exon 17b. TLN1 is comprised of an N-terminal FERM domain, linked to 13 force-dependent switch domains, R1-R13. Inclusion of exon 17b introduces an in-frame insertion of 17 amino acids immediately after Gln665 in the region between R1 and R2 which lowers the force required to open the R1-R2 switches potentially altering downstream mechanotransduction. Biochemical analysis of this isoform revealed enhanced vinculin binding, and cells expressing this variant show altered adhesion dynamics and motility. Finally, we showed that the TGF-β/SMAD3 signaling pathway regulates this isoform switch. Future studies will need to consider the balance of these two TLN1 isoforms.
Targeting type 2 immunity and the future of food allergy treatment
Authors: Berin M. Cecilia
Published: March 2023

IgE-mediated food allergy affects 6–8% of the population in the United States. Type 2 immune responses are central to the pathogenesis of food allergy, but type 2 CD4+ T cell responses have been found to be heterogeneous in food allergy suggesting a division of labor between Tfh13 and peTH2 cells in promotion of IgE class switching, modulation of intestinal barrier function, and regulation of mast cell expansion. Oral immunotherapy for the treatment of food allergy incompletely targets subsets of type 2 immunity in a transient manner, but new therapeutics targeting different levels of type 2 immunity are in current or planned trials for food allergy. These new treatments and the basis for their use are the focus of this review.
Intestinal cell type-specific communication networks underlie homeostasis and response to Western diet
Authors: Wang Yu-Chen , Cao Yang , Pan Calvin , Zhou Zhiqiang , Yang Lili , Lusis Aldons J.
Published: March 2023

The small intestine plays a key role in immunity and mediates inflammatory responses to high fat diets. We have used single-cell RNA-sequencing (scRNA-seq) and statistical modeling to examine gaps in our understanding of the dynamic properties of intestinal cells and underlying cellular mechanisms. Our scRNA-seq and flow cytometry studies of different layers of intestinal cells revealed new cell subsets and modeled developmental trajectories of intestinal intraepithelial lymphocytes, lamina propria lymphocytes, conventional dendritic cells, and enterocytes. As compared to chow-fed mice, a high-fat high-sucrose (HFHS) “Western” diet resulted in the accumulation of specific immune cell populations and marked changes to enterocytes nutrient absorption function. Utilizing ligand–receptor analysis, we profiled high-resolution intestine interaction networks across all immune cell and epithelial structural cell types in mice fed chow or HFHS diets. These results revealed novel interactions and communication hubs among intestinal cells, and their potential roles in local as well as systemic inflammation.
Sidestepping SHP2 inhibition
Authors: Popescu Bogdan , Shannon Kevin
Published: March 2023

Allosteric SHP2 inhibitors are a novel class of compounds that target hyperactive Ras/Mitogen Activated Protein Kinase (MAPK) signaling. In this issue of JEM, Wei et al. (2023. J. Exp. Med.https://doi.org/10.1084/jem.20221563) report a genome-wide CRISPR/Cas9 knockout screen that uncovered novel mechanisms of adaptive resistance to pharmacologic inhibition of SHP2.
FRC-derived retinoic acid: The key to unlocking milky spots
Authors: Daley Alexander D. , Bénézech Cécile
Published: March 2023

Milky spots of the omentum enable lymphocyte access to the peritoneal cavity. In this issue of JEM, Yoshihara and Okabe (2023. J. Exp. Med.https://doi.org/10.1084/jem.20221813) demonstrate how secretion of retinoic acid by fibroblastic reticular cells allows lymphocyte entry into milky spots and the peritoneal cavity.
Graviton scattering in self-dual radiative space-times
Authors: Adamo Tim , Mason Lionel , Sharma Atul
Published: March 2023

The construction of amplitudes on curved space-times is a major challenge, particularly when the background has non-constant curvature. We give formulae for all tree-level graviton scattering amplitudes in curved self-dual (SD) radiative space-times; these are chiral, source-free, asymptotically flat spaces determined by free characteristic data at null infinity. Such space-times admit an elegant description in terms of twistor theory, which provides the powerful tools required to exploit their underlying integrability. The tree-level S-matrix is written in terms of an integral over the moduli space of holomorphic maps from the Riemann sphere to twistor space, with the degree of the map corresponding to the helicity configuration of the external gravitons. For the MHV sector, we derive the amplitude directly from the Einstein–Hilbert action of general relativity, while other helicity configurations arise from a natural family of generating functionals and pass several consistency checks. The amplitudes in SD radiative space-times exhibit many novel features that are absent in Minkowski space, including tail effects. There remain residual integrals due to the functional degrees of freedom in the background space-time, but our formulae have many fewer such integrals than would be expected from space-time perturbation theory. In highly symmetric special cases, such as SD plane waves, the number of residual integrals can be further reduced, resulting in much simpler expressions for the scattering amplitudes.
Thickness-dependent catalytic activity of hydrogen evolution based on single atomic catalyst of Pt above MXene
Authors: Shu Zheng , Cai Yongqing
Published: March 2023

Hydrogen as the cleanest energy carrier is a promising alternative renewable resource to fossil fuels. There is an ever-increasing interest in exploring efficient and cost-effective approaches of hydrogen production. Recent experiments have shown that single platinum atom immobilized on the metal vacancies of MXenes allows a high-efficient hydrogen evolution reaction (HER). Here using ab initio calculations, we design a series of substitutional Pt-doped Ti
n

+ 1C
n
T
x
(Ti
n

+ 1C
n
T
x
-PtSA) with different thicknesses and terminations (n = 1, 2 and 3, T
x
= O, F and OH), and investigate the quantum-confinement effect on the HER catalytic performance. Surprisingly, we reveal a strong thickness effect of the MXene layer on the HER performance. Among the various surface-terminated derivatives, Ti2CF2-PtSA and Ti2CH2O2-PtSA are found to be the best HER catalysts with the change of Gibbs free energy ΔG
H* ∼ 0 eV, complying with the thermoneutral condition. The ab initio molecular dynamics simulations reveal that Ti2CF2-PtSA and Ti2CH2O2-PtSA possess a good thermodynamic stability. The present work shows that the HER catalytic activity of the MXene is not solely governed by the local environment of the surface such as Pt single atom. We point out the critical role of thickness control and surface decoration of substrate in achieving a high-performance HER catalytical activity.
Assessment of 2D-based tests for the qualification of simulation software for dXCT
Authors: Borges de Oliveira Fabrício , Reuter Tamara , Plotzki David , Wohlgemuth Florian , Batscher Markus , Bellon Carsten , Kasperl Stefan
Published: March 2023

The interest in using computer simulations of dimensional x-ray computed tomography (dXCT) for various metrological purposes—such as measurement planning, performance prediction, performance optimisation and, finally, measurement uncertainty estimation—is increasing along with the ever-growing demand for more reliable measurements with dXCT. However, before a piece of simulation software can be used for tasks related to coordinate metrology, it has to be ensured that it is able to simulate physical laws, characteristic effects and basic CT system functionalities correctly and with sufficient accuracy. In short, the software must be qualified for dimensional metrology tasks. As one part of such a qualification process, a method is presented here for determining conformity intervals of 2D tests (projection-based tests) based on 3D tests (testing based on dimensional evaluations in a reconstructed volume) for the assessment of dXCT simulation software. The method consists of varying relevant parameter values in order to verify their influence on 3D measurement results. The results of the 3D tests with varied parameter values are then transferred to the quantities tested in the 2D tests and used as the basis for determining conformity intervals. Two approaches are applied for determining whether or not a variation of a parameter value is significant: (a) statistical and (b) heuristic. Two examples are presented, each based on simulated images, which show the application of the two different approaches for determining conformity intervals for the results of the 2D tests.