bluuebunny/crossref_metadata_2025 huggingface dataset:
A Herschel study of the high-mass protostar IRAS 20126+4104
Authors: Cesaroni R. , Faustini F. , Galli D. , Lorenzani A. , Molinari S. , Testi L.
Published: February 2023

We performed Herschel observations of the continuum and line emission from the high-mass star-forming region IRAS 20126+4104, which hosts a well-studied B-type (proto)star powering a bipolar outflow and is associated with a Keplerian circumstellar disk. The continuum images at six wavelengths allowed us to derive an accurate estimate of the bolometric luminosity and mass of the molecular clump enshrouding the disk. The same region has been mapped in 12 rotational transitions of carbon monoxide, which were used in synergy with the continuum data to determine the temperature and density distribution inside the clump and improve upon the mass estimate. The maps of two fine structure oxygen far-IR lines were used to estimate the volume density of the shocked region at the surface of the southern lobe of the outflow and the mass-loss rate. Our findings lend further support to the scenario previously proposed by various authors, confirming that at the origin of the bolometric luminosity and bipolar outflow from IRAS 20126+4104 is a B-type star located at the centre of the Keplerian disk.
Geothermal water as a nutrient medium source on the biomass productivity and biochemical composition of Spirulina (Arthrospira platensis) under the greenhouse conditions
Authors: Güroy Betül , Güroy Derya , Mantoğlu Serhan , Karadal Onur , Oğuzkan Sibel Bayil
Published: February 2023

Spirulina (Arthrospira platensisGomont, 1892) is grown in highly alkaline waters and is an important ingredient for many industries. However, analytical grade-based media in used commercial-scale production of Spirulina is quite expensive. Spirulina cultivation was studied by replacing the Schlösser medium with geothermal water in terms of its biomass, biochemical content, amino acid and mineral production. Spirulina was cultured in a semi-open raceway system with a 420 L culture volume for three weeks. Then, the geothermal water (GW) was replaced with 25% (GW25), 50% (GW50), 75% (GW75) and 100% (GW100) of the volume of the Schlösser culture medium (SM). The biomass concentration was determined to the higher in the GW50 (1.324 g/L) than in other groups (GW25, GW75, GW100 and SM), while the minimum yield was in GW100 (0.624 g/L) group. The highest protein content and phycocyanin purity ratio were found in the GW75 medium containing 116.6 times higher phosphate than the SM. The chlorophyll content of SM, GW25 and GW50 was higher than that of the GW100 (P< 0.05). The highest lipid content was determined in the GW100 (P< 0.05). Isoleucine, leucine and valine levels of the GW50 and GW75 were higher than those of the other groups (P< 0.05). The iron levels of the GW50 and GW75 groups, which have the highest nitrate content in the culture mediums, were significantly lower. The chlorophyll, phycocyanin, protein, dry biomass, mineral and amino acid in groups (GW25, GW50 and GW75) prepared by mixing Schlösser medium and geothermal water mix were better than geothermal water (GW100) and SM. As a result, it is concluded that it is possible to use partial geothermal water in Spirulina production under this study conditions.
Efficacy of HIV and AIDS education programs in the Elmina fishing community in Ghana
Authors: Kyei-Gyamfi Sylvester
Published: February 2023

One of the most important steps in HIV prevention is the provision of education to raise awareness to ensure individuals have a sufficient understanding of HIV and AIDS and encourage them to apply that knowledge. The study is based on an earlier descriptive cross-sectional study that sought a link between fishers’ mobility and their risk of HIV exposure in the Elmina fishing community in Ghana. The current paper focuses on initiatives taken within the study area to inform fishers about HIV and AIDS. Additionally, it analyzes the successes and challenges of these programs and offers suggestions for improvement. Public and community durbars, town hall meetings, radio and television transmission, film creation, and the distribution of IE&C materials are the main strategies utilized to carry out HIV and AIDS education. The results suggest that few fishers in the study area take part in programs, whiles projects on HIV and AIDS cannot be implemented consistently and effectively due to a lack of funding and delays in the delivery of government funds. To enable organizations whose mandates, relate to HIV and AIDS interventions to carry out the programs timely and fully, it is advised that government enhances its financing and ensures the timely and full release of program funds.
A method for measuring electron temperature and ion density with immunity to RF fluctuation and ion current
Authors: Eo Hyundong , Kim Kyung-Hyun , Lee Moo-Young , Kim Ju Ho , Chung Chin-Wook
Published: February 2023

A measurement method immune to radio frequency (RF) fluctuations is proposed for obtaining electron temperature and plasma density in RF discharges. The self-bias voltage formed by applying a square voltage to a floating planar probe and its fundamental frequency current are measured to obtain electron temperature and plasma density. To investigate the change in electron temperature due to RF distortion, the case with and without RF filters is compared, and our method is least affected by RF fluctuations compared to the conventional methods: electron energy probability function (EEPF) and floating harmonic method (FHM). When the RF powers and the gas pressures change, the electron temperature and the ion density measured from our method agree well with those measured from the FHM. Although our method and the EEPF are slightly different due to the depletion of the EEPF at high energy (near the floating potential), the trends of the three methods (our method, FHM, and EEPF) agree well under all conditions. In our method, the electron temperature was investigated with and without correction for the increase in the ion current at probe tip radii of 5 and 1 mm. When correcting the increase in ion current due to the sheath expansion, the electron temperature is not overestimated and does not change in the planar probe with a small radius. This can be useful in plasma monitoring system where an RF filter cannot be installed, or the probe tip must be made small.
Engineering living materials by synthetic biology
Authors: Luo Jiren , Chen Jiangfeng , Huang Yaoge , You Lingchong , Dai Zhuojun
Published: February 2023

Natural biological materials are programmed by genetic information and able to self-organize, respond to environmental stimulus, and couple with inorganic matter. Inspired by the natural system and to mimic their complex and delicate fabrication process and functions, the field of engineered living materials emerges at the interface of synthetic biology and materials science. Here, we review the recent efforts and discuss the challenges and future opportunities.
Toward more robust ignition of inertial fusion targets
Authors: Lee J. J. , Ruskov R. T. , Martin H. , Hughes S. , von der Layen M. W. , Paddock R. W. , Timmis R. , Ouatu I. , Feng Q. S. , Howard S. , Atonga E. , Aboushelbaya R. , Arber T. D. , Bingham R. , Norreys P. A.
Published: February 2023

Following the 3.15 MJ fusion milestone at the National Ignition Facility, the further development of inertial confinement fusion, both as a source for future electricity generation and for high-energy-density physics applications, requires the development of more robust ignition concepts at current laser facility energy scales. This can potentially be achieved by auxiliary heating the hotspot of low convergence wetted foam implosions where hydrodynamic and parametric instabilities are minimized. This paper presents the first multi-dimensional Vlasov–Maxwell and particle-in-cell simulations to model this collisionless interaction, only recently made possible by access to the largest modern supercomputers. The key parameter of interest is the maximum fraction of energy that can be extracted from the electron beams into the hotspot plasma. The simulations indicate that significant coupling efficiencies are achieved over a wide range of beam parameters and spatial configurations. The implications for experimental tests on the National Ignition Facility are discussed.
2D absolute position measurement based on the hybrid encoding method
Authors: Zhao Huining , Niu Ruru , Fan Mengyao , Xia Haojie
Published: February 2023

This paper introduces a new method of absolute position measurement based on the hybrid encoding principle that can precisely measure the absolute position of a two-dimensional (2D) micro displacement table. The method uses pseudo-random sequences and binary codes to generate the long-distance position encoding sequences. It combines the encoding sequences with checkerboards to form a hybrid encoding to complete the design of the 2D encoding of plane positions. Then a 2D encoding disk is designed as a tool to measure 2D absolute position. Among them, the X and Y positions are designed by the modular approach, respectively, to efficiently detect the accuracy of 2D position values during the measurement. Moreover, the designed 2D encoding disk can quickly realize image correction. In order to verify the feasibility of the designed 2D encoding disk for measuring the 2D absolute position, the corresponding measurement system is built using a 2D encoding disk, a CCD camera, and a telecentric lens. The experimental results demonstrate that the average position deviation of the 2D absolute position measurement system is less than ±1 µm.
Neutron imaging of inertial confinement fusion implosions
Authors: Fittinghoff D. N. , Birge N. , Geppert-Kleinrath V.
Published: February 2023

We review experimental neutron imaging of inertial confinement fusion sources, including the neutron imaging systems that have been used in our measurements at the National Ignition Facility. These systems allow measurements with 10 µm resolution for fusion deuterium–deuterium and deuterium–tritium neutron sources with mean radius up to 400 µm, including measurements of neutrons scattered to lower energy in the remaining cold fuel. These measurements are critical for understanding the fusion burn volume and the three-dimensional effects that can reduce the neutron yields.
Steering particles via micro-actuation of chemical gradients using model predictive control
Authors: McDonald Mark N. , Peterson Cameron K. , Tree Douglas R.
Published: February 2023

Biological systems rely on chemical gradients to direct motion through both chemotaxis and signaling, but synthetic approaches for doing the same are still relatively naïve. Consequently, we present a novel method for using chemical gradients to manipulate the position and velocity of colloidal particles in a microfluidic device. Specifically, we show that a set of spatially localized chemical reactions that are sufficiently controllable can be used to steer colloidal particles via diffusiophoresis along an arbitrary trajectory. To accomplish this, we develop a control method for steering colloidal particles with chemical gradients using nonlinear model predictive control with a model based on the unsteady Green’s function solution of the diffusion equation. We illustrate the effectiveness of our approach using Brownian dynamics simulations that steer single particles along paths, such as circle, square, and figure-eight. We subsequently compare our results with published techniques for steering colloids using electric fields, and we provide an analysis of the physical parameter space where our approach is useful. Based on these findings, we conclude that it is theoretically possible to explicitly steer particles via chemical gradients in a microfluidics paradigm.
Self-similar bubble-front evolutions of ablative Rayleigh–Taylor instability seeded by localized perturbations
Authors: Fu J. Y. , Zhang H. S. , Cai H. B. , Zhu S. P.
Published: February 2023

Two-dimensional numerical simulations are carried out to investigate the nonlinear bubble growth of ablative Rayleigh–Taylor instability (ARTI) seeded by localized perturbations (LPs), where the LPs are described by a Gaussian mode. It is found that the nonlinear bubble-front penetration of LP-seeded ARTI follows the self-similar scaling law αbAT∫gdt2, different from the classical case, where the self-similar behavior is not observed. It is also found that the quadratic growth coefficient αb in the LP-seeded ARTI mainly depends on the initial perturbation amplitude and initial perturbation width. When the perturbation amplitude is small, αb has a value of ∼0.03, which is not sensitive to the perturbation width. As the perturbation amplitude increases, the value of αb increases, and the phenomenon is more significant when the perturbation width is narrower. It is shown that the increase in αb is due to the spike-induced upward jet and the ablation-generated vorticity inside the bubble.
Physical-level secure wireless communication using random-signal-excited reprogrammable metasurface
Authors: Wei Menglin , Zhao Hanting , Chen Yanjin , Wang Zhuo , Cui Tie Jun , Li Lianlin
Published: February 2023

Security is a critical issue in wireless communication due to the broadcast nature of the wireless environment; thus, physical-level secure wireless communication is of great importance in modern society, especially with the advent of the Internet-of-Things, fifth-generation, and beyond. In this Letter, we present an efficient scheme of physical-level secure wireless communication by exploring the reprogrammable metasurface excited with random signals at the transmission side (Alice) and the dual-receiver decoding method at the receiving side (Bob). To that end, the bit stream to be transferred is first encoded into the reprogrammable metasurface on the physical level, then the information-carrying metasurface is excited by a sequence of random radio signals; finally, Alice's information is retrieved by processing coherently the random signals acquired by two receivers at Bob. It is apparent that the eavesdropper (Eve) with a single antenna somewhere only receives the noise radiated from the metasurface and cannot decode the information correctly. Note that the reprogrammable metasurface with the time-space coding pattern shows the information-dependent radiation pattern, i.e., different noises in different directions. Therefore, our wireless communication method is also effective to the eavesdropper with multiple antennas. We implement a proof-of-principle system working at around 2.442 GHz and demonstrate experimentally that the proposed method enables to transmit the Mbps-rate bitstream. Our work will pave the way toward next-generation secure wireless communication.
Prediction of internal and external flow with sparse convolution neural network: A computationally effective reduced-order model
Authors: Peng Jiang-Zhou , Aubry Nadine , Hua Yue , Chen Zhi-Hua , Wu Wei-Tao , Chen Siheng
Published: February 2023

This paper presents a novel reduced-order model for internal and external flow field estimations based on a sparse convolution neural network. Since traditional convolution neural network requires “rectangular” matrixes as input, the convolutional operation is computationally inefficient when applied to these problems with input matrix having sparse information. In our approach, we innovatively introduce a sparse convolution neural network (SCNN) to collect spatial information on geometries that are inherently sparse, e.g., the flow in thin pipelines in a much larger domain or the pipelines with random branches. Different from the traditional convolution neural network (CNN) model, the SCNN only collects features from areas with flow information for both the input matrix and each convolutional layer, which not only reduces the consumption of computational resources but also significantly increases network attention to flow area. The model learns the mapping relationship between geometries and the physical field of fluid flow, and the spatial positions of geometry are represented using the nearest wall signed distance function. The proposed SCNN model has the promising adaptability to arbitrary geometry and less computational resource cost compared to the traditional CNN model: the mean error of the SCNN is less than 5.4% (while the CNN is 7.1%) for the internal flow and less than 6.5% (while the CNN is 8.1%) for the external flow. Moreover, the SCNN has 72% less GPU resource usage and 52% less random access memory cost than the CNN for internal flow. For the first time, our framework introduces the sparse convolution network to flow field prediction, and the SCNN shows outstanding performance on prediction accuracy and computational resource saving for the flow problems with a sparse input information.
Stability of a Szegő-type asymptotics
Authors: Müller Peter , Schulte Ruth
Published: February 2023

We consider a multi-dimensional continuum Schrödinger operator H, which is given by a perturbation of the negative Laplacian by a compactly supported bounded potential. We show that for a fairly large class of test functions, the second-order Szegő-type asymptotics for the spatially truncated Fermi projection of H is independent of the potential and, thus, identical to the known asymptotics of the Laplacian.
Pfaffian solutions and nonlinear waves of a (3 + 1)-dimensional generalized Konopelchenko–Dubrovsky–Kaup–Kupershmidt system in fluid mechanics
Authors: Shen Yuan , Tian Bo , Cheng Chong-Dong , Zhou Tian-Yu
Published: February 2023

Fluid mechanics is concerned with the behavior of liquids and gases at rest or in motion, where the nonlinear waves and their interactions are important. Hereby, we study a (3 + 1)-dimensional generalized Konopelchenko–Dubrovsky–Kaup–Kupershmidt system in fluid mechanics. We determine a bilinear form of that system via the Hirota method. Nth-order Pfaffian solutions are obtained via the Pfaffian technique and our bilinear form, where N is a positive integer. Based on the Nth-order Pfaffian solutions, we derive the N-soliton, higher-order breather, and hybrid solutions. Using those solutions, we present the (1) elastic interaction between the two solitary waves with a short stem, (2) elastic interaction between the two solitary waves with a long stem, (3) fission between the two solitary waves, (4) fusion between the two solitary waves, (5) one breather wave, (6) elastic interaction between the two breather waves, (7) fission between the two breather waves, (8) fusion among the one breather wave and two solitary waves, and (9) elastic interaction between the one breather wave and one solitary wave.
On the effect of streamwise and spanwise spacing to height ratios of three-dimensional sinusoidal roughness on turbulent boundary layers
Authors: Abdelaziz Misarah , Djenidi L. , Ghayesh Mergen H. , Chin Rey
Published: February 2023

A developing zero pressure gradient (ZPG) turbulent boundary layer (TBL) over different three-dimensional (3D) sinewave roughnesses is investigated experimentally using single hot-wire anemometry. Seven different sinewave profiles are fabricated with the same amplitude and with different wavelengths in the streamwise (sx) and spanwise (sz) directions. The effects of varying sx and sz on turbulence statistics and the drag coefficient (Cf) are assessed. The wall-unit normalized streamwise mean velocity profile is shifted downward compared with the smooth wall profile for all roughnesses. The streamwise spacing to height ratio sx/k has a more significant effect on the roughness function ΔU+ and Cf compared with the spanwise spacing to height ratio sz/k. However, sz/k has a large impact on the streamwise turbulence intensities in the log and outer layer. An excellent collapse is observed among the mean streamwise velocity profiles plotted in defect form in the outer region. However, a lack of similarity between TBLs over different rough surfaces is observed in the outer region for the turbulence intensities profiles. For isotropic 3D sinusoidal roughness (equal streamwise and spanwise spacing to height ratios), the contours of premultiplied streamwise turbulent energy spectrograms show an increase in energy in the outer layer with increasing spacing to height ratios. For anisotropic 3D sinusoidal roughness (unequal streamwise and spanwise spacing to height ratios), the contours of premultiplied streamwise turbulent energy spectrograms show an increase in energy in the outer layer with increasing sz/sx from half to two in this study.
Theory and simulations of linear and nonlinear two-dimensional Rayleigh–Taylor dynamics with variable acceleration
Authors: Chan Wai Hong Ronald , Jain Suhas S. , Hwang Hanul , Naveh Annie , Abarzhi Snezhana I.
Published: February 2023

Interfacial Rayleigh–Taylor mixing is crucial to describing important natural and engineering processes, such as exploding supernovae, laser micromachining, hot spots in inertial confinement fusion, and optical telecommunications. These require the characterization of the time dependence of the driving acceleration. We compare our theoretical formulation based on group theory foundations with interface-capturing numerical simulations for linear and nonlinear two-dimensional Rayleigh–Taylor instabilities in a finite-sized domain with time-varying acceleration over broad ranges of Atwood numbers and acceleration exponents. Detailed corroboration between theory and simulations is provided for this foundational case. Both demonstrate the strong interfacial nature of Rayleigh–Taylor instabilities, which suggests that practical flow fields can be reconstructed from the derived fluid potential using the proposed theory. A robust agreement is also obtained for the early and late-time evolution of the amplitudes of the bubble and spike, which demonstrate that the Rayleigh–Taylor flow can transition to the mixing regime even for a single-mode initial perturbation. Corroboration with experiments of high energy density plasmas motivated by studies of supernovae is also achieved. In addition, a long-standing puzzle in Rayleigh–Taylor dynamics on the interplay between the acceleration, the shear, and the interface morphology in the theory and simulations is resolved by accounting for finite viscosity of the fluids. The characterization of Rayleigh–Taylor instabilities as a highly interfacial phenomenon provides valuable insight into its multiscale nature, which enhances the design and understanding of numerous processes of practical interest.
Theoretical prediction model of transient performance for a mixed flow pump under fast start-up conditions
Authors: Liu Ming , Han Yadong , Tan Lei , Lu Yangping , Ma Can , Gou Jinlan
Published: February 2023

There always appear unsteady characteristics during start-up periods of pumps, which can lead to instability of the entire system. However, the lack of a method for quickly and accurately predicting pump start-up performance makes it difficult to analyze the performance of the overall system during the period. To this end, a theoretical model to predict pump transient performance under fast start-up conditions is established in the present study. The theoretical prediction model for pump steady performance is built based on loss modeling first. Then, the balance between pump transient head and pipeline system is considered to determine transient pump performance. A time stepping algorithm is proposed to solve transient pump performance during start-up periods. The established theoretical model and the corresponding time stepping algorithm are applied to a mixed flow pump under fast start-up conditions with various acceleration time. The predicted evolution of pump head shows good agreement with experimental measurements, and average relative errors are within 10% for both steady and transient conditions. In addition, the theoretical model is applied to analyze the transient performance of oscillating curves and impact head. The mechanism for predicted oscillating results and the relation between peak impact head and the acceleration of rotation speed are revealed.
Molecular understanding of the Helmholtz capacitance difference between Cu(100) and graphene electrodes
Authors: Li Xiang-Ying , Jin Xiang-Feng , Yang Xiao-Hui , Wang Xue , Le Jia-Bo , Cheng Jun
Published: February 2023

Unraveling the origin of Helmholtz capacitance is of paramount importance for understanding the interfacial structure and electrostatic potential distribution of electric double layers (EDL). In this work, we combined the methods of ab initio molecular dynamics and classical molecular dynamics and modeled electrified Cu(100)/electrolyte and graphene/electrolyte interfaces for comparison. It was proposed that the Helmholtz capacitance is composed of three parts connected in series: the usual solvent capacitance, water chemisorption induced capacitance, and Pauling repulsion caused gap capacitance. We found the Helmholtz capacitance of graphene is significantly lower than that of Cu(100), which was attributed to two intrinsic factors. One is that graphene has a wider gap layer at interface, and the other is that graphene is less active for water chemisorption. Finally, based on our findings, we provide suggestions for how to increase the EDL capacitance of graphene-based materials in future work, and we also suggest that the new understanding of the potential distribution across the Helmholtz layer may help explain some experimental phenomena of electrocatalysis.
Coercivity enhancement of hot-deformed NdFeB magnets by in situ two-end-diffusion with R70Cu30 alloy powders (R = NdPr and Ce)
Authors: Wong Y. J. , Huang W. M. , Chang H. W. , Chang W. C.
Published: February 2023

We hereby present a simple process, called in situ two-end diffusion (TED), to reach coercivity enhancement with almost unchanged energy product for hot deformed (HD) NdFeB magnets. Coercivity of the HD magnets is increased from 15.1 to 18.7 kOe for the magnet TED with (Nd0.75Pr0.25)70Cu30 (NdPrCu), which is larger than 17.6 kOe for the magnet directly doped with 2 wt. % NdPrCu alloy. Besides, the magnet TED with NdPrCu exhibits good (00L) texture and therefore could support high (BH)max of 43.0 MGOe. In addition, the magnet TED with Ce70Cu30 (CeCu) exhibit superior magnetic properties of Br = 12.8 kG, iHc = 18.0 kOe and (BH)max = 40.7 MGOe to those of traditional doping with CeCu (Br = 11.7 kG, iHc = 16.4 kOe and (BH)max = 34.2 MGOe). For TED process, low-melting CeCu can infiltrate into the center of the magnet, and most Ce distribute at grain boundary. The distribution of Ce and Cu at grain boundary can reduce the magnetization of grain boundary phase, strengthen the decoupling effect between grains and contribute to the coercivity enhancement. This work demonstrates TED with low-melting HRE-free alloys is a simple method to effectively enhance coercivity and keep high Br and (BH)max for HD NdFeB magnets.
Effect of quenching rate on the structural and hard magnetic properties of Nd-Fe-B melt-spun ribbons
Authors: Singh Sudeep , Diraviam Arvindha Babu , Sarkar Rajdeep , Haldar Arabinda , Muthuvel Manivel Raja
Published: February 2023

The phase structure, microstructure, magnetic and thermomagnetic properties of nanostructured Nd–Fe–B melt-spun ribbons were investigated. The melt-spun ribbons have been prepared at different wheel speeds varying from 17 to 25 m/s. The hard magnetic Nd2Fe14B phase with (00l) texture, indicating preferred crystallographic orientation, was observed in all the ribbons with some α-Fe(Co) as the minor phase. Nd2Fe14B grains are uniformly distributed with grain sizes ranging from 50 to 150 nm. A decrease in the average grain size of Nd2Fe14B and fading away of texture formation in the ribbons were found with the increase in the wheel speeds. The best combination of magnetic properties with a coercivity of 14.5 kOe, the saturation magnetization of 132 emu/g, and the energy product of 16 MGOe was achieved at 23 m/s and these ribbons are suitable for the fabrication of hot deformation Nd–Fe–B magnets.
Structural, magnetic, and magnetocaloric characterization of NiMnSn microwires prepared by Taylor-Ulitovsky technique
Authors: Arreguín-Hernández M. L. , Varga M. , Hennel M. , Dzubinska A. , Ryba T. , Reiffers M. , Diko P. , Llamazares J. L. Sánchez , Varga R.
Published: February 2023

We report the structural, magnetic, and magnetocaloric characterization of glass-coated Ni42.9Mn37.1Sn20.0 microwires produced by the Taylor-Ulitovsky method. Microwire samples crystallized into a single-phase austenite with the L21-type crystal structure (space group Fm3̄m, lattice parameter a ≈ 6.02 Å) and a Curie temperature of 349 K. A distinctive feature of the produced microwires is that saturation magnetization is reached at a very low magnetic field (∼0.15 T). For a magnetic field change of 3 T, the produced microwires showed a reversible maximum magnetic entropy change |ΔSM|max of 2.3 J kg−1 K−1 and a refrigerant capacity of 197 J kg−1, which are similar to the values reported by other austenitic NiMnSn alloys produced by rapid quenching techniques.
A solid-state failure of the Born–Oppenheimer approximation
Authors: Miller Johanna L.
Published: February 2023

According to a keystone principle of molecular physics, atoms striking semiconductor surfaces shouldn’t excite surface electrons. But they do.
Conformational rearrangements in the second voltage sensor domain switch PIP
2
- and voltage-gating modes in two-pore channels
Authors: Shimomura Takushi , Hirazawa Kiichi , Kubo Yoshihiro
Published: February 2023

Two-pore channels (TPCs) are activated by phosphatidylinositol bisphosphate (PIP
2
) binding to domain I and/or by voltage sensing in domain II (DII). Little is known about how these two stimuli are integrated, and how each TPC subtype achieves its unique preference. Here, we show that distinct conformations of DII-S4 in the voltage-sensor domain determine the two gating modes. DII-S4 adopts an intermediate conformation, and forced stabilization in this conformation was found to result in a high PIP
2
-dependence in primarily voltage-dependent TPC3. In TPC2, which is PIP
2
-gated and nonvoltage-dependent, a stabilized intermediate conformation does not affect the PIP
2
-gated currents. These results indicate that the intermediate state represents the PIP
2
-gating mode, which is distinct from the voltage-gating mode in TPCs. We also found in TPC2 that the tricyclic antidepressant desipramine induces DII-S4-based voltage dependence and that naringenin, a flavonoid, biases the mode preference from PIP
2
-gating to desipramine-induced voltage gating. Taken together, our study on TPCs revealed an unprecedented mode-switching mechanism involving conformational changes in DII-S4, and its active role in integrating voltage and PIP
2
stimuli.
CRISPR metabolic screen identifies ATM and KEAP1 as targetable genetic vulnerabilities in solid tumors
Authors: Li Haojian , Liu Yue , Xiao Yunjie , Wilson Crystal N. , Bai Hui Jen , Jones Maxwell D. , Wang Shihchun , DeVore Jennie E. , Maier Esther Y. , Durant Stephen T. , Boufraqech Myriem , Weyemi Urbain
Published: February 2023

Cancer treatments targeting DNA repair deficiencies often encounter drug resistance, possibly due to alternative metabolic pathways that counteract the most damaging effects. To identify such alternative pathways, we screened for metabolic pathways exhibiting synthetic lethality with inhibition of the DNA damage response kinase Ataxia-telangiectasia-mutated (ATM) using a metabolism-centered Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 library. Our data revealed Kelch-like ECH-associated protein 1 (KEAP1) as a key factor involved in desensitizing cancer cells to ATM inhibition both in vitro and in vivo. Cells depleted of KEAP1 exhibited an aberrant overexpression of the cystine transporter SLC7A11, robustly accumulated cystine inducing disulfide stress, and became hypersensitive to ATM inhibition. These hallmarks were reversed in a reducing cellular environment indicating that disulfide stress was a crucial factor. In The Cancer Genome Atlas (TCGA) pan-cancer datasets, we found that ATM levels negatively correlated with KEAP1 levels across multiple solid malignancies. Together, our results unveil ATM and KEAP1 as new targetable vulnerabilities in solid tumors.
A virus-induced circular RNA maintains latent infection of Kaposi’s sarcoma herpesvirus
Authors: Tagawa Takanobu , Oh Daniel , Dremel Sarah , Mahesh Guruswamy , Koparde Vishal N. , Duncan Gerard , Andresson Thorkell , Ziegelbauer Joseph M.
Published: February 2023

Non-coding RNAs (ncRNAs) play important roles in host-pathogen interactions; oncogenic viruses like Kaposi’s sarcoma herpesvirus (KSHV) employ ncRNAs to establish a latent reservoir and persist for the life of the host. We previously reported that KSHV infection alters a novel class of RNA, circular RNAs (circRNAs). CircRNAs are alternative splicing isoforms and regulate gene expression, but their importance in infection is largely unknown. Here, we showed that a human circRNA, hsa_circ_0001400, is induced by various pathogenic viruses, namely KSHV, Epstein-Barr virus, and human cytomegalovirus. The induction of circRNAs including circ_0001400 by KSHV is co-transcriptionally regulated, likely at splicing. Consistently, screening for circ_0001400-interacting proteins identified a splicing factor, PNISR. Functional studies using infected primary endothelial cells revealed that circ_0001400 inhibits KSHV lytic transcription and virus production. Simultaneously, the circRNA promoted cell cycle, inhibited apoptosis, and induced immune genes. RNA-pull down assays identified transcripts interacting with circ_0001400, including
TTI1
, which is a component of the pro-growth mTOR complexes. We thus identified a circRNA that is pro-growth and anti-lytic replication. These results support a model in which KSHV induces circ_0001400 expression to maintain latency. Since circ_0001400 is induced by multiple viruses, this novel viral strategy may be widely employed by other viruses.
Inducible disruption of
Tet
genes results in myeloid malignancy, readthrough transcription, and a heterochromatin-to-euchromatin switch
Authors: Yuita Hiroshi , López-Moyado Isaac F. , Jeong Hyeongmin , Cheng Arthur Xiuyuan , Scott-Browne James , An Jungeun , Nakayama Toshinori , Onodera Atsushi , Ko Myunggon , Rao Anjana
Published: February 2023

The three mammalian TET dioxygenases oxidize the methyl group of 5-methylcytosine in DNA, and the oxidized methylcytosines are essential intermediates in all known pathways of DNA demethylation. To define the in vivo consequences of complete TET deficiency, we inducibly deleted all three
Tet
genes in the mouse genome.
Tet1/2/3-inducible TKO
(
iTKO
) mice succumbed to acute myeloid leukemia (AML) by 4 to 5 wk. Single-cell RNA sequencing of
Tet iTKO
bone marrow cells revealed the appearance of new myeloid cell populations characterized by a striking increase in expression of all members of the
stefin/cystatin
gene cluster on mouse chromosome 16. In patients with AML, high
stefin/cystatin
gene expression correlates with poor clinical outcomes. Increased expression of the clustered
stefin/cystatin
genes was associated with a heterochromatin-to-euchromatin compartment switch with readthrough transcription downstream of the clustered
stefin/cystatin
genes as well as other highly expressed genes, but only minor changes in DNA methylation. Our data highlight roles for TET enzymes that are distinct from their established function in DNA demethylation and instead involve increased transcriptional readthrough and changes in three-dimensional genome organization.
Structures of human gastrin-releasing peptide receptors bound to antagonist and agonist for cancer and itch therapy
Authors: Peng Shuman , Zhan Yuting , Zhang Dongqi , Ren Lu , Chen Anqi , Chen Zhou-Feng , Zhang Haitao
Published: February 2023

Gastrin releasing peptide receptor (GRPR), a member of the bombesin (BBN) G protein-coupled receptors, is aberrantly overexpressed in several malignant tumors, including those of the breast, prostate, pancreas, lung, and central nervous system. Additionally, it also mediates non-histaminergic itch and pathological itch conditions in mice. Thus, GRPR could be an attractive target for cancer and itch therapy. Here, we report the inactive state crystal structure of human GRPR in complex with the non-peptide antagonist PD176252, as well as two active state cryo-electron microscopy (cryo-EM) structures of GRPR bound to the endogenous peptide agonist gastrin-releasing peptide and the synthetic BBN analog [D-Phe
6
, β-Ala
11
, Phe
13
, Nle
14
] Bn (6–14), in complex with G
q
heterotrimers. These structures revealed the molecular mechanisms for the ligand binding, receptor activation, and G
q
proteins signaling of GRPR, which are expected to accelerate the structure-based design of GRPR antagonists and agonists for the treatments of cancer and pruritus.
Structural basis of V-ATPase V
O
region assembly by Vma12p, 21p, and 22p
Authors: Wang Hanlin , Bueler Stephanie A. , Rubinstein John L.
Published: February 2023

Vacuolar-type adenosine triphosphatases (V-ATPases) are rotary proton pumps that acidify specific intracellular compartments in almost all eukaryotic cells. These multi-subunit enzymes consist of a soluble catalytic V
1
region and a membrane-embedded proton-translocating V
O
region. V
O
is assembled in the endoplasmic reticulum (ER) membrane, and V
1
is assembled in the cytosol. However, V
1
binds V
O
only after V
O
is transported to the Golgi membrane, thereby preventing acidification of the ER. We isolated V
O
complexes and subcomplexes from
Saccharomyces cerevisiae
bound to V-ATPase assembly factors Vma12p, Vma21p, and Vma22p. Electron cryomicroscopy shows how the Vma12-22p complex recruits subunits a, e, and f to the rotor ring of V
O
while blocking premature binding of V
1
. Vma21p, which contains an ER-retrieval motif, binds the V
O
:Vma12-22p complex, “mature” V
O
, and a complex that appears to contain a ring of loosely packed rotor subunits and the proteins YAR027W and YAR028W. The structures suggest that Vma21p binds assembly intermediates that contain a rotor ring and that activation of proton pumping following assembly of V
1
with V
O
removes Vma21p, allowing V-ATPase to remain in the Golgi. Together, these structures show how Vma12-22p and Vma21p function in V-ATPase assembly and quality control, ensuring the enzyme acidifies only its intended cellular targets.
Adverbial clauses and their variation
Authors: Jędrzejowski Łukasz , Fleczoreck Constanze
Published: February 2023

In this introduction chapter, we depict the variation of adverbial clauses focusing on causal clauses in German. We briefly overview the most important findings both from a synchronic and diachronic point of view, and embed them into a more general discussion on adverbial clause-linkage.
On the divergent developments of two German causal subjunctions
Authors: Eberhardt Ira , Axel-Tober Katrin
Published: February 2023

This chapter discusses the development of two German causal subjunctions weil and zumal. In particular, it introduces a new proposal for the syntactic reanalysis of weil in the C0-position from a free relative clause. Later, weil-clauses also underwent a shift in meaning in the course of which weil developed from a temporal into a causal subjunction. The development of temporal into causal meaning is widely-attested cross-linguistically. This chapter argues that in the case of German, the actuation of this general path was probably enabled by prior extensions of the temporal meaning, which had made the subjunction into a universal subjunction of simultaneity relations. The subjunction zumal, by contrast, developed from the combination zumal weil ‘especially since’ after zumal had been reanalyzed in the C0-position. The reanalysis only concerned the internal syntax of the clause. Its external syntax and the meaning remained stable and corresponded to zumal weil-clauses. Based on these findings, it will be argued more generally that the development of new elements in the C0-position takes place through the fusion of the properties of the new and the old C0-elements. After the reanalysis, the new C0-element has the subordinating force of the old C0-element as well as the semantic content of the new and the old C0-element.
Factors for the integration of causal clauses in the history of German
Authors: Speyer Augustin , Voigtmann Sophia
Published: February 2023

The variation between integrated (verb-final) and independent (verb-second) causal clauses in German could depend on the amount of information conveyed in that clause. A lower amount might lead to integration, a higher amount to independence, as processing constraints might forbid integration of highly informative clauses. We use two ways to measure information amount: 1. the average ratio of given referents within the clause, 2. the cumulative surprisal of all words in the clause. Focusing on historical stages of German, a significant correlation between amount of information and integration was visible, regardless which method was used.
Optimization of CFTR gating through the evolution of its extracellular loops
Authors: Simon Márton A. , Csanády László
Published: February 2023

CFTR chloride channel mutations cause the lethal and incurable disease cystic fibrosis (CF). CFTR is activated by phosphorylation, and phosphorylated channels exhibit “bursting” behavior—“bursts” of openings separated by short “flickery” closures and flanked by long “interburst” closures—driven by ATP binding/hydrolysis at two nucleotide-binding domains. The human channel (hCFTR) and the distant zebrafish ortholog (zCFTR) display differences both in their gating properties and structures. In phosphorylated ATP-bound hCFTR, the hR117 side chain, conserved across evolution, forms an H-bond that stabilizes the open state. Lack of that bond in the hR117H mutant causes CF. In the phosphorylated ATP-bound zCFTR structure that H-bond is not observable. Here, we show that the zR118H mutation does not affect the function of zCFTR. Instead, we identify an H-bond between the zS109 and zN120 side chains of phosphorylated ATP-bound, but not of unphosphorylated apo-, zCFTR. We investigate the role of that interaction using thermodynamic mutant cycles built on gating parameters determined in inside-out patch clamp recordings. We find that zS109 indeed forms an H-bond with zN120 in the flickery closed state, but not in the open or interburst closed states. Although in hCFTR an isoleucine (hI119) replaces the asparagine, mutation hS108A produces a strong hR117H-like phenotype. Since the effects of the latter two mutations are not additive, we conclude that in hCFTR these two positions interact, and the hS108-hR117 and hR117-hE1124 H-bonds cooperate to stabilize the open state. These findings highlight an example of how the gating mechanism was optimized during CFTR molecular evolution.
Second order symmetry operators for the massive Dirac equation
Authors: Jacobsson Simon , Bäckdahl Thomas
Published: February 2023

Employing the covariant language of two-spinors, we find what conditions a curved four-dimensional Lorentzian spacetime must satisfy for existence of a second order symmetry operator for the massive Dirac equation. The conditions are formulated as existence of a set of Killing spinors satisfying a set of covariant linear differential equations. Using these Killing spinors, we then state the most general form of such an operator. Partial results for the zeroth and first order are presented and interpreted as well. Computer algebra tools from the Mathematica package suite xAct were used for the calculations.
Exponential moments for disk counting statistics of random normal matrices in the critical regime
Authors: Charlier Christophe , Lenells Jonatan
Published: February 2023

We obtain largenasymptotics for them-point moment generating function of the disk counting statistics of the Mittag–Leffler ensemble, wherenis the number of points of the process andmis arbitrary but fixed. We focus on the critical regime where all disk boundaries are merging at speedn−12, either in the bulk or at the edge. As corollaries, we obtain two central limit theorems and precise largenasymptotics of all joint cumulants (such as the covariance) of the disk counting function. Our results can also be seen as largenasymptotics forn × ndeterminants with merging planar discontinuities.
A numerical and experimental study on positive diffusive ionization waves in different N2/O2 mixtures: the role of photoionization
Authors: Guo Yulin , Li Yanru , Zhu Yifei , Sun Anbang
Published: February 2023

A diffusive ionization wave can be generated by an ultrafast high voltage far exceeding the inception threshold, and is featured by its unique and repetitive conical morphology. A combinative experimental and numerical study of the diffusive ionization waves is conducted in this work to investigate the role of photoionization in different N2/O2 mixtures with oxygen concentrations of 20%, 2%, 0.2%, 1 ppm, and pure nitrogen. In all gas mixtures, the ionization wave first forms a spherical shape after its inception then a conical when it approaches the plane electrode. Compared with typical filamentary streamers and inception cloud generated by low overvoltage, photoionization in a diffusive ionization wave takes effects mainly before the formation of the spherical ionization wave, and affects slightly the propagation velocity, discharge morphology, and the width (diameter) of the ionization wave. When the pin-to-plane electrode gap distance is kept 16 mm, in the atmospheric pressure simulation with an 85 kV voltage pulse, the maximum ionization width decreases from 11.4 mm in the 20% mixture to 9.1 mm in pure nitrogen. In the 200 mbar pressure experiment with a 16 kV voltage pulse, the maximum ionization width decreases from 12.5 mm in the 20% mixture to 11.6 mm in pure nitrogen. E in the inception cloud diameter estimation function (D= 2 U
E
−1) is modified to estimate the width of the ionization wave during its spherical propagation stage. It is shown that the estimation results at 180–205 kV cm−1 are in good agreement with the simulation results at atmospheric pressure air.
Experimental study of the effect of dielectric materials on the decomposition of carbon dioxide in a dielectric barrier discharge
Authors: Liu Chang-Yu , Wang Hai-Xing , Wang Chao , Meng Xian , Huang He-Ji , Cao Jin-Wen , Sun Su-Rong , Yan Cong
Published: February 2023

The low-temperature nonequilibrium characteristics of dielectric barrier discharge (DBD) make it an important candidate for the decomposition and conversion of CO2. In this study, quartz, alumina and zirconia are selected as the dielectrics to investigate the effect of dielectric materials of planar DBD reactor on the discharge and conversion characteristics of CO2. It is shown that under the same input power conditions, zirconia has the highest CO2 conversion rate when used as a dielectric, followed by alumina, and quartz has the lowest. Combined with the analysis of the measured electrical characteristics, it is shown that zirconia has the highest transferred charge, thus further increasing the discharge efficiency. Experimental results of the single dielectric barrier layer-metal mesh electrode reactor show that the CO2 discharge can operate in the lower power range and the CO2 conversion rate is higher than that of the double dielectric barrier layer reactor. Spectroscopic measurements show that the emission intensity of the discharge in the reactor with high relative permittivity materials is higher than that in the case of low relative permittivity materials, and the emission intensity of the single dielectric layer reactor is also higher than that in the case of the double dielectric layer reactor.