bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of wall wettability effects on cavitation bubble collapse using lattice Boltzmann method
Authors: Yuan Hao , Zhang Jianbao , Zhou Jiayu , Tan Jiawan , Wang Zhaobing , Gan Weidong
Published: June 2021

This study investigates the effects of wall wettability on cavitation bubble collapse using the pseudopotential lattice Boltzmann method with an appropriate external force term and wall contact angle boundary condition. The accuracy of the proposed numerical approach is verified by simulating a single-bubble collapse near a neutral wall. The result shows that the wettability condition of the wall has a significant effect on the forces exerted on cavitation bubbles. For a hydrophilic surface, there is a repulsive force between the surface and the bubble, whereas for a hydrophobic surface, the force is attractive. The wall wettability affects the evolution of the bubble shape, the maximum collapse pressure, the microjet velocity, and the total kinetic energy of the cavitation bubble during its collapse. Changing the wettability from hydrophobic to hydrophilic decreases the maximum pressure and microjet velocity but increases the cavitation bubble lifetime. Furthermore, the range of wall effects is smaller for a hydrophilic wall than for a hydrophobic wall.
Discriminating Gaussian processes via quadratic form statistics
Authors: Balcerek Michał , Burnecki Krzysztof , Sikora Grzegorz , Wyłomańska Agnieszka
Published: June 2021

Gaussian processes are powerful tools for modeling and predicting various numerical data. Hence, checking their quality of fit becomes a vital issue. In this article, we introduce a testing methodology for general Gaussian processes based on a quadratic form statistic. We illustrate the methodology on three statistical tests recently introduced in the literature, which are based on the sample autocovariance function, time average mean-squared displacement, and detrended moving average statistics. We compare the usefulness of the tests by taking into consideration three very important Gaussian processes: the fractional Brownian motion, which is self-similar with stationary increments (SSSIs), scaled Brownian motion, which is self-similar with independent increments (SSIIs), and the Ornstein–Uhlenbeck (OU) process, which is stationary. We show that the considered statistics’ ability to distinguish between these Gaussian processes is high, and we identify the best performing tests for different scenarios. We also find that there is no omnibus quadratic form test; however, the detrended moving average test seems to be the first choice in distinguishing between same processes with different parameters. We also show that the detrended moving average method outperforms the Cholesky method. Based on the previous findings, we introduce a novel procedure of discriminating between Gaussian SSSI, SSII, and stationary processes. Finally, we illustrate the proposed procedure by applying it to real-world data, namely, the daily EURUSD currency exchange rates, and show that the data can be modeled by the OU process.
Hybrid reaction–diffusion and clock-and-wavefront model for the arrest of oscillations in the somitogenesis segmentation clock
Authors: Pantoja-Hernández Jesús , Breña-Medina Víctor F. , Santillán Moisés
Published: June 2021

The clock and wavefront paradigm is arguably the most widely accepted model for explaining the embryonic process of somitogenesis. According to this model, somitogenesis is based upon the interaction between a genetic oscillator, known as segmentation clock, and a differentiation wavefront, which provides the positional information indicating where each pair of somites is formed. Shortly after the clock and wavefront paradigm was introduced, Meinhardt presented a conceptually different mathematical model for morphogenesis in general, and somitogenesis in particular. Recently, Cotterell et al. [A local, self-organizing reaction-diffusion model can explain somite patterning in embryos, Cell Syst. 1, 257-269 (2015)] rediscovered an equivalent model by systematically enumerating and studying small networks performing segmentation. Cotterell et al. called it a progressive oscillatory reaction–diffusion (PORD) model. In the Meinhardt–PORD model, somitogenesis is driven by short-range interactions and the posterior movement of the front is a local, emergent phenomenon, which is not controlled by global positional information. With this model, it is possible to explain some experimental observations that are incompatible with the clock and wavefront model. However, the Meinhardt–PORD model has some important disadvantages of its own. Namely, it is quite sensitive to fluctuations and depends on very specific initial conditions (which are not biologically realistic). In this work, we propose an equivalent Meinhardt–PORD model and then amend it to couple it with a wavefront consisting of a receding morphogen gradient. By doing so, we get a hybrid model between the Meinhardt–PORD and the clock-and-wavefront ones, which overcomes most of the deficiencies of the two originating models.
Coupling characteristics between cylindrical hybrid plasmon waveguide and cylindrical silicon nanowire waveguide
Authors: Liu Jian-Ping , Wang Wei-Lin , Xie Fang , Li Chen , Zhou Xia , Yu Ji-Hai , Li Si-Qi , Wang Ling-Ling
Published: June 2021

Cylindrical waveguides have a wide range of applications in photonic integrated circuits because of lower transmission losses. This paper proposes a directional coupler composed of a cylindrical silicon nanowire waveguide and a metal-based cylindrical hybrid plasmon waveguide. The coupling characteristics of the coupler are analyzed theoretically and are also simulated using the finite-difference time-domain method. The results show that the coupler can operate effectively with a relatively short coupling length, displaying low insertion loss, and a high coupling efficiency and extinction ratio. This study also shows how the TM mode in the plasmon waveguide can be excited with the TE mode of the dielectric waveguide. This directional coupler has a potential application in signal exchanging and mode switching between the dielectric and plasmon waveguides in photonic integrated circuits.
Spreading and mixing during solutal convection in uniform porous media with application to geologic CO2 storage
Authors: Eckel A.-M. , Pini R.
Published: June 2021

Convective dissolution in saline aquifers is expected to positively impact subsurface storage of carbon dioxide (CO2) by accelerating its dissolution rate into reservoir brines. By largely focusing on the dissolution flux, previous studies lack a systematic evaluation of the mixing process following CO2 emplacement, including a quantitative analysis at conditions representative of subsurface traps (Rayleigh number, Ra≤1 000). Here, we investigate solutal convection numerically in a two-dimensional uniform porous medium in the regime Ra=100−10 000. The macroscopic evolution of the convective process is characterized by means of fundamental macroscopic measures of mixing that use the local spatial structure of the solute concentration field. It is shown that the intensity of segregation closely mimics the evolution of the in situ convective pattern arising from the stretching and merging of downwelling plumes. The spreading length and the dilution index both confirm that the mixing process accelerates over time (t) with a power law scaling (∝tα) that transitions from diffusive (α=0.5) to superdiffusive mixing (α≥1) irrespective of Ra. This transition time scales τon∝Ra−2 and is used as a measure of the onset time of convection. The dilution index indicates that the time needed to reach close-to-complete mixing reduces linearly with Ra. On the contrary, the non-dimensional mass flux, expressed in terms of the Sherwood number, Sh, reveals a natural logarithmic scaling for Ra≤2 500.
Approximations of density matrices in N-electron valence state second-order perturbation theory (NEVPT2). I. Revisiting the NEVPT2 construction
Authors: Guo Yang , Sivalingam Kantharuban , Neese Frank
Published: June 2021

Over the last decade, the second-order N-electron valence state perturbation theory (NEVPT2) has developed into a widely used multireference perturbation method. To apply NEVPT2 to systems with large active spaces, the computational bottleneck is the construction of the fourth-order reduced density matrix. Both its generation and storage become quickly problematic beyond the usual maximum active space of about 15 active orbitals. To reduce the computational cost of handling fourth-order density matrices, the cumulant approximation (CU) has been proposed in several studies. A more conventional strategy to address the higher-order density matrices is the pre-screening approximation (PS), which is the default one in the ORCA program package since 2010. In the present work, the performance of the CU, PS, and extended PS (EPS) approximations for the fourth-order density matrices is compared. Following a pedagogical introduction to NEVPT2, contraction schemes, as well as the approximations to density matrices, and the intruder state problem are discussed. The CU approximation, while potentially leading to large computational savings, virtually always leads to intruder states. With the PS approximation, the computational savings are more modest. However, in conjunction with conservative cutoffs, it produces stable results. The EPS approximation to the fourth-order density matrices can reproduce very accurate NEVPT2 results without any intruder states. However, its computational cost is not much lower than that of the canonical algorithm. Moreover, we found that a good indicator of intrude states problems in any approximation to high order density matrices is the eigenspectra of the Koopmans matrices.
Approximations of density matrices in N-electron valence state second-order perturbation theory (NEVPT2). II. The full rank NEVPT2 (FR-NEVPT2) formulation
Authors: Guo Yang , Sivalingam Kantharuban , Kollmar Christian , Neese Frank
Published: June 2021

In Paper I, the performances of pre-screening (PS), extended PS (EPS), and cumulant (CU) approximations to the fourth-order density matrix were examined in the context of second-order N-electron valence state perturbation theory (NEVPT2). It has been found that the CU, PS, and even EPS approximations with loose thresholds may introduce intruder states. In the present work, the origin of these “false intruder” states introduced by approximated density matrices is discussed. Canonical NEVPT2 implementations employ a rank reduction trick. By analyzing its residual error, we find that the omission of the rank reduction leads to a more stable multireference perturbation theory for incomplete active space reference wave functions. Such a full rank (FR)-NEVPT2 formulation is equivalent to the conventional NEVPT2 method for the complete active space self-consistent field/complete active space configuration interaction reference wave function. A major drawback of the FR-NEVPT2 formulation is the necessity of the fifth-order density matrix. To avoid the construction of the high-order density matrices, the combination of the FR-NEVPT2 with the CU approximation is studied. However, we find that the CU approximation remains problematic as it still introduces intruder states. The question of how to robustly and efficiently perform internally contracted multireference perturbation theories with approximate densities remains a challenging field of investigation.
α-phase PVDF MEMS cantilever excited by electrostriction and evaluated up to 160 °C in air by laser-Doppler vibrometry
Authors: Maier F. J. , Schneider M. , Ullmann P. , Hafner J. , Schmid U.
Published: June 2021

The electroactive polymer polyvinylidene fluoride (PVDF) has gained much interest in smart materials research with a wide application range for industry and consumer applications due to the low cost, flexibility, chemical resistance, non-toxicity, and light weight. In this work, we present an α-phase PVDF cantilever that exploits electrostriction as the main transducer mechanism for excitation. We realize thin PVDF films with a thickness of ∼190 nm and a low roughness (∼19 nm RMS). Electrostrictive cantilevers need high electric fields to achieve amplitudes comparable to piezoelectric counterparts. At thinner films, lower voltage levels are requested for comparable electric fields, thus making electrostrictive PVDF cantilevers a viable route and subsequently allowing broader use of PVDF in MEMS devices. We use an asymmetric electrode design that has the advantage of shifting the neutral axis out of the PVDF without enhancing cantilever thickness with a supporting device layer. In addition, these devices can be produced by CMOS compatible micromachining techniques. We measured the electrostrictive and piezoelectric actuation signal with laser-Doppler vibrometry and showed the frequency spectrum and curvature of such α-phase PVDF cantilevers. The cantilevers have a curvate of up to 120 m−1 at 1500 kV/cm. We demonstrate that the electrostrictive actuation has a low temperature dependency in the range from 25 up to 130 °C. A typical cantilever exhibits a geometry dependent low spring constant (k ∼ 0.3 N m−1) and a low quality factor (Q ∼ 75) in air.
Synopsis of Vogel–Escudier flow
Authors: Sharma Manjul , Sameen A.
Published: June 2021

The topology and the dynamics of Vogel–Escudier flow, which is the flow inside a circular cylinder with a top rotating lid, are presented in this paper. A three-dimensional direct numerical simulation of the Navier–Stokes equations in cylindrical coordinates is used to investigate the flow. Various combinations of Reynolds number and aspect ratio are studied and classified based on the flow topology. The flow is found to exhibit steady axisymmetric, unsteady axisymmetric, rotating azimuthal waves, and weak turbulence regimes. The perturbations found in the system are characteristically different for various flow regimes and are used for the classification of flow. The presence of several modes at high Reynolds number suggests a weak turbulence state, and a Taylor–Görtler type instability wave is found in the sidewall boundary layer.
High-pressure methane adsorption behavior on deep shales: Experiments and modeling
Authors: Shen Weijun , Li Xizhe , Ma Tianran , Cai Jianchao , Lu Xiaobing , Zhou Shangwen
Published: June 2021

Understanding methane adsorption behavior on deep shales is crucial for estimating the original gas in place and enhancing gas recovery in deep shale gas formations. In this study, the methane adsorption on deep shales within the lower Silurian Longmaxi formation from the Sichuan Basin, South China was conducted at pressures up to 50 MPa. The effects of total organic carbon (TOC), temperatures, clay minerals, and moisture content on the adsorption capacity were discussed. The results indicated that the methane excess adsorption on deep shales increased, then reached its peak, and finally decreased with the pressure. The excess adsorption data were fitted using the adsorption models, and it was found that the Dubinin–Radushkevich (D–R) model was superior to other models in predicting the methane adsorption behavior. The methane adsorption capacities exhibited strong positive correlations with the TOC content and negative relationships with clay minerals. The methane excess adsorption decreased with the temperature, while the opposite trend would occur once it exceeded some pressure. The presence of the moisture content on deep shales sharply decreased the methane adsorption capacities, and the reduction of the adsorption capacity decreased with the pressure. The moisture would occupy the adsorption sites in the shale pores, which could result in the methane adsorption capacity that decreased.
Fabrication and broadband ferromagnetic resonance studies of freestanding polycrystalline yttrium iron garnet thin films
Authors: Zhang Lei , Zhang Dainan , Jin Lichuan , Liu Bo , Meng Hao , Tang Xiaoli , Li MingMing , Liu Shuai , Zhong Zhiyong , Zhang Huaiwu
Published: June 2021

Flexible magnetic materials and devices with basic functional properties are highly desirable for flexible electronic applications in wearable products and implantable systems. In this work, a freestanding polycrystalline yttrium iron garnet (YIG) thin film with strong magnetism has been synthesized by pulsed laser deposition using a water-dissolvable Sr3Al2O6 sacrificial layer, and the magnetism of the resulting freestanding film was confirmed by a vibrating sample magnetometer and broadband ferromagnetic resonance spectroscopy. When transferred to a support layer using a thermal release tape, the flexible polycrystalline YIG thin film exhibits a lower damping constant α and larger magnetocrystalline anisotropy, in contrast to the polycrystalline heterostructure of YIG, which arises due to stress release. Thus, this work offers a viable solution for flexible YIG thin films that can be used in a number of applications.
TP53
missense mutations in PDAC are associated with enhanced fibrosis and an immunosuppressive microenvironment
Authors: Maddalena Martino , Mallel Giuseppe , Nataraj Nishanth Belugali , Shreberk-Shaked Michal , Hassin Ori , Mukherjee Saptaparna , Arandkar Sharathchandra , Rotkopf Ron , Kapsack Abby , Lambiase Giuseppina , Pellegrino Bianca , Ben-Isaac Eyal , Golani Ofra , Addadi Yoseph , Hajaj Emma , Eilam Raya , Straussman Ravid , Yarden Yosef , Lotem Michal , Oren Moshe
Published: June 2021

Significance

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer, which is presently refractory to all available therapeutic strategies. PDAC tumors are characterized by a high degree of fibrosis, believed to be a major contributor to their therapy resistance. Mutations in the
TP53
tumor suppressor gene are very frequent in PDAC. We now report that
TP53
missense mutations, which lead to production of mutant p53 proteins, increase the extent of fibrosis and reduce the infiltration of cytotoxic CD8
+
T cells. The inhibition of CD8
+
T cell infiltration may augment the ability of PDAC tumors to evade the immune system. Hence, inhibition of the activities of mutant p53 may potentially sensitize PDAC tumors to anticancer treatments, including immunotherapy.
Converging evidence for greater male variability in time, risk, and social preferences
Authors: Thöni Christian , Volk Stefan
Published: June 2021

Significance

There is continuing interest in the study of gender differences in economic and social outcomes. An important factor underlying gender differences in outcomes are gender differences in fundamental economic preferences, which are at the core of many differential choices of women and men. We provide strong evidence for greater male variability in preferences. We find that men are more likely to have extreme time, risk, and social preferences, while women are more likely to have moderate preferences. With the focus on mean differences, the current literature underestimates the importance of gender differences and their effects on differential choices and outcomes between women and men.
The relationship between birth timing, circuit wiring, and physiological response properties of cerebellar granule cells
Authors: Shuster S. Andrew , Wagner Mark J. , Pan-Doh Nathan , Ren Jing , Grutzner Sophie M. , Beier Kevin T. , Kim Tony Hyun , Schnitzer Mark J. , Luo Liqun
Published: June 2021

Significance

Cerebellar granule cells (GrCs) comprise the majority of all neurons in the mammalian brain and are usually regarded as a uniform cell type. However, the birth timing of individual GrCs dictates where their axons project. Using viral-genetic techniques, we find that early- and late-born GrCs receive different proportions of inputs from the same set of input regions. In vivo multidepth two-photon Ca
2+
imaging of axons of early- and late-born GrCs reveals that both populations represent diverse task variables and stimuli, with small differences in the proportions of axons in encoding of a subset of movement and reward parameters. These results indicate that birth timing makes a modest contribution to the input selection and physiological response properties of GrCs.
Phosphate Elimination and Recovery Lightweight (PEARL) membrane: A sustainable environmental remediation approach
Authors: Ribet Stephanie M. , Shindel Benjamin , dos Reis Roberto , Nandwana Vikas , Dravid Vinayak P.
Published: June 2021

Significance

The large scale of pollution requires solutions that are efficient and effective while meeting economic and engineering considerations. We report the Phosphate Elimination and Recovery Lightweight (PEARL) membrane, a nanocomposite that can be used to selectively and repeatably recover phosphate at will from contaminated waters. The PEARL membrane is made through a scalable, aqueous process. An inexpensive porous structure is coated with a slurry of nanostructures tailored for selective sorption of pollutants. Characterization of the PEARL membrane provides compelling scientific insights into its complex architecture and its binding of phosphate. The PEARL membrane approach is potentially general and versatile such that it can be tuned to remediate other contaminants with the same core principles of performance, scalability, reusability, and cost-effectiveness.
Regulation of cold-induced thermogenesis by the RNA binding protein FAM195A
Authors: Cannavino Jessica , Shao Mengle , An Yu A. , Bezprozvannaya Svetlana , Chen Shiuhwei , Kim Jiwoong , Xu Lin , McAnally John R. , Scherer Philipp E. , Liu Ning , Gupta Rana K. , Bassel-Duby Rhonda , Olson Eric N.
Published: June 2021

Significance

Activation of brown adipose tissue offers a strategy for enhancing energy expenditure to counteract obesity and other metabolic disorders. The discovery of novel factors regulating brown adipose tissue function has implications in therapeutic intervention to treat metabolic dysfunction. Here, we discover a previously uncharacterized RNA binding protein called FAM195A and show that genetically engineered mice lacking FAM195A are severely cold intolerant and have abnormalities in branched-chain amino acid metabolism. In vitro studies showed that FAM195A is required for the expression of enzymes involved in branched-chain amino acid catabolism. This study reveals FAM195A to be a link between thermoregulation, metabolism, and RNA processes, highlighting FAM195A as an important regulator of brown adipose tissue activation.
Multiphoton Ionization of Potassium Atoms in Femtosecond Laser Fields
Authors: Li Wankai , Lei Yue , Li Xing , Yang Tao , Du Mei , Jiang Ying , Li Jialong , Luo Sizuo , Liu Aihua , He Lanhai , Ma Pan , Zhang Dongdong , Ding Dajun
Published: June 2021

We study the multiphoton ionization of potassium atoms in 800 nm and 400 nm femtosecond laser fields. In the 800 nm laser field, the potassium atom absorbs three photons and emits one electron via one photon resonance with the 4p intermediate state with the help of the ac-Stark shift. The resonance feature is clearly shown as an Autler–Townes (AT) splitting and is mapped out in the electron kinetic energy spectrum. In a 400 nm laser field, although one photon resonance is possible with the 5p state, no splitting is observed. The different transition amplitudes between 4s–4p and 4s–5p explain the observed results. Due to the AT effect, an unexpected peak in the photoelectron energy spectrum that violates the dipole transition rule is observed. A preliminary explanation involving the spin-orbit interaction in the p state is given to account for this component. The observed AT-splitting in the electron kinetic energy distribution can be used as an effective method to calibrate the intensity of a laser field.
Broadband Terahertz Wave Generation from Monolayer Graphene Driven by Few-Cycle Laser Pulse
Authors: Guan Zhong , Wang Guo-Li , Zhang Lei , Jiao Zhi-Hong , Zhao Song-Feng , Zhou Xiao-Xin
Published: June 2021

We theoretically investigate the characteristics of terahertz (THz) radiation from monolayer graphene exposed to normal incident few-cycle laser pulses, by numerically solving the extended semiconductor Bloch equations. Our simulations show that the THz spectra in low frequency regions are highly dependent on the carrier envelope phase (CEP) of driving laser pulses. Using an optimal CEP of few-cycle laser pulses, we can obtain broadband strong THz waves, due to the symmetry breaking of the laser-graphene system. Our results also show that the strength of the THz spectra depend on both the intensity and central wavelength of the laser pulses. The intensity dependence of the THz wave can be described by the excitation rate of graphene, while wavelength dependence can be traced back to the band velocity and the population of graphene. We find that a near single-cycle THz pulse can be obtained from graphene driven by a mid-infrared laser pulse.
Electrochemical Behavior of Vanadium Carbide in Neutral Aqueous Electrolytes
Authors: Chen Chaofan , Pang Di , Wang Xiaotong , Chen Gang , Du Fei , Gao Yu
Published: June 2021

The V2C compound, belonging to the group of two-dimensional transition metal carbonitrides, or MXenes, has demonstrated a promising electrochemical performance in capacitor applications in acidic electrolytes; however, there is evidence to suggest that V2C is unstable in an acidic environment. On the other hand, the performance of V2C in neutral aqueous electrolytes is still moderate, and has not yet been systematically studied. The charge storage mechanism in a V2C electrode, employed in neutral aqueous electrolytes, is investigated via cyclic voltammetry testing and in situ x-ray diffraction (XRD). Good specific capacitances are achieved, specifically 208 F/g in 0.5 M Li2SO4, 225 F/g in 1 M MgSO4, 120 F/g in 1M Na2SO4, and 104 F/g in 0.5 M K2SO4. Using in situ XRD, we observe that, during the charge and discharge process, the c-lattice parameter shrinks or expands by up to 0.25 Å in MgSO4, and 0.29 Å in Li2SO4 which demonstrates the intercalation/de-intercalation of cations into the d-V2C layer.
Ghost imaging-based optical cryptosystem for multiple images using integral property of the Fourier transform*
Authors: Kang Yi , Zhang Leihong , Ye Hualong , Zhang Dawei , Zhuang Songlin
Published: June 2021

A novel ghost imaging-based optical cryptosystem for multiple images using the integral property of the Fourier transform is proposed. Different from other multiple-image encryption schemes, we mainly construct the modulation patterns related to the plaintext images to realize the encrypted transmission of multiple images. In encryption process, the first image is encrypted by the ghost imaging encryption scheme, and the intensity sequence obtained by the bucket detector is used as the ciphertext. Then modulation patterns of other images are constructed by using the integral property of the Fourier transform and used as the keys. Finally, the ciphertext and keys are transmitted to the receiver to complete the encryption process. During decryption, the receiver uses different keys to decrypt the ciphertext and gets different plaintext images, and decrypted images have no image aliasing problem. Experiments and simulations verify the feasibility, security, and robustness of the proposed scheme. This scheme has high scalability and broad application prospect, which provides a new idea for optical information encryption.
Thermal apoptosis analysis considering injection behavior optimization and mass diffusion during magnetic hyperthermia
Authors: Tang Yun-Dong , Zou Jian , Flesch Rodolfo C C , Jin Tao , He Ming-Hua
Published: June 2021

Thermally induced apoptosis for tumors depends mainly on the intrinsic characteristics of biological tissues as well as treatment temperature profile during magnetic hyperthermia. Further, treatment temperature distribution inside tumor depends on the injection behavior of irregular tumors, such as the injection dose and the injection location of nanofluids. In order to improve the treatment effect, the simulated annealing algorithm is adopted in this work to optimize the nanofluid injection behavior, and the improved Arrhenius model is used to evaluate the malignant ablations for three typical malignant tumor cell models. In addition, both the injection behavior optimization and the mass diffusion of nanofluid are both taken into consideration in order to improve the treatment effect. The simulation results demonstrate that the injection behavior can be optimized effectively by the proposed optimization method before therapy, the result of which can also conduce to improving the thermal apoptosis possibility for proposed typical malignant cells. Furthermore, an effective approach is also employed by considering longer diffusion duration and correct power dissipation at the same time. The results show that a better result can then be obtained than those in other cases when the power dissipation of MNPs is set to be Q
MNP = 5.4 × 107 W·m3 and the diffusion time is 16 h.
Phase transitions of light in a dye-filled microcavity: observations and simulations
Authors: Nyman R.A. , Dhar H.S. , Rodrigues J.D. , Mintert F.
Published: June 2021

Photon thermalisation and condensation in dye-filled microcavities is a growing area of scientific interest, at the intersection of photonics, quantum optics and statistical physics. We give here a short introduction to the topic, together with an explanation of some of our more important recent results. A key result across several projects is that we have a model based on a detailed physical description which has been used to accurately describe experimental observations. We present a new open-source package in Python called PyPBEC which implements this model. The aim is to enable the reader to readily simulate and explore the physics of photon condensates themselves, so this article also includes a working example code which can be downloaded from the GitHub repository.
An advanced lifetime measurement method by square wave excitation and lock-in amplifier
Authors: Çodur M Mustafa , Yercİ Selçuk
Published: June 2021

Achieving the radiation decay rate with high accuracy is crucial for all light emitters and absorbers. Therefore, a wide variety of measurement approaches have been developed for the measurement of radiation decay rate. Herein, we introduce a method to measure the decay rate with a common photoluminescence intensity setup without any modification. The square wave created by simply turning the output of the laser on and off is used as the excitation waveform, and a lock-in amplifier is used to gather the detected signal, making it a cost-effective way. Moreover, the constructed method can be used in a wide range of frequencies, detection voltages, and lifetimes. Finally, we applied the derived method to measure the photoluminescence lifetime of the first excited state of erbium ions in upconverting erbium-ytterbium silicate samples.
Application of Background Oriented Schlieren method for diagnostics of surface discharge
Authors: Korotkikh I , Malakhov Yu , Skornyakova N
Published: June 2021

The results of visualization of an electrical discharge arising on the surface of glass or plastic are presented. This type of discharge is used for formation, research, control the parameters of ozonizers; as a source of ultraviolet radiation; in the study of the parameters around surfaces of gas or plasma flows. The possibility of using the background oriented shlieren method for determining the temperature field of a surface discharge is shown in paper.
Superconducting YBCO ceramics after exposure to a plasma flow to a mixture of argon and oxygen
Authors: Kh Gadzhimagomedov S , Palchaev D K , Kh Gadzhiev M , Murlieva Zh Kh , Kh Rabadanov M , Saypulaev P M , Demirov N A , Emirov R M , Rabadanova A E
Published: June 2021

The structure and properties of superconducting nanostructured ceramics YBa 2Cu 3O7-y (YBCO) before and after exposure to a plasma flow consisting of a mixture of argon and oxygen (at ∼ 600 °C for ∼ 1 min) are investigated. Plasma surface treatment, in addition to compaction of grains, leads to a change in the oxygen stoichiometry index and average crystallite size, as well as to a decrease in the proportion of the superconducting phase in the ceramic. After plasma treatment of ceramics, the character of the temperature dependence of the electrical resistance ρ = f (T) changes from metallic to semiconductor, and the temperature T
c, onset remains constant.
The study of electric arc travel velocity properties in circular plasmatron
Authors: Samigullin A D , Saetgaraev D D
Published: June 2021

This article presents the results of calculated electric arc travel velocity in a circular plasmatron. The calculation of the electric arc travel velocity should consider a set of parameters and factors from the current strength to running inductance of parallel electrodes.
On the issue of modeling the processing of materials by plasma of a vapor-gas discharge with liquid electrodes
Authors: Takseitov R R , Galimova R K , Yakupov Z Y
Published: June 2021

This work describes a method for using the power parameters of the Lennard-Jones central potential to simulate phenomena in the technology of material processing by a vapor-gas discharge plasma with a liquid electrode.
Distribution of the Heat Flux on the Axis in a Uniform Closed Tube with Highly Non-Linear Resonant Gas Oscillations
Authors: Kabirov A A , Shaidullin L R
Published: June 2021

The results of an experimental study of the acoustothermal effect, which is large for nonlinear gas oscillations in a closed pipe at a resonant frequency, are presented. The distribution of the heat flow along the tube is obtained. It was found that at the ends of the closed tube, the heat flow takes maximum and positive values, which indicates the heating of the gas. In the middle of the tube, the gas takes on minimum values, which indicates cooling in this area.
Forced resonance gas oscillations in different cross-sections of a closed tube with a sudden change of the section diameter
Authors: Shaidullin L R , Zaripov R G , Tkachenko L A , Kabirov A A
Published: June 2021

Experimental results of forced gas oscillations in narrow and wide parts of a closed tube are presented. It was found that the gas pressure in the wide part of the tube close to the oscillator is higher than the pressure in the narrow part.
Study of forced gas oscillations in a cube with a diaphragm near resonance
Authors: Gubaidullin D A , Zaripov R G , Tkachenko L A , Shaidullin L R , Kabirov A A
Published: June 2021

The results of studies of forced resonance gas oscillations in a cubic resonator are presented. It was found that the presence of a diaphragm in the resonator neck leads to an increase in the amplitude of gas pressure oscillations in the cube.
Features of shock-wave compression of cavitation bubble content during collapse in acetone and tetradecane
Authors: Yu Toporkov D
Published: June 2021

Strong compression of the medium in cavitation bubbles during their collapse in acetone at temperatures of 273 and 293 K and tetradecane at a temperature of 663 K is considered. The features of the behavior of the maximum values of the thermodynamic parameters in the case of the formation of converging shock and isentropic compression waves inside the bubbles in wide ranges of the liquid pressures are studied. The influence of the shock and isentropic waves and their mutual interaction on the level of the maximum values of the thermodynamic parameters attained inside the bubbles is illustrated.
Powder production of from low-alloy steel by flame atomization
Authors: Gabdrakhmanov Az T , Israphilov I H , Galiakbarov A T , Gabdrakhmanova T F
Published: June 2021

The advantages of plasma atomization technology in comparison with other methods of powder production for additive technologies are shown in this paper. Investigations of powders obtained by plasma atomization from welding wire sv-08G2S (similar to ER70S-6) with a diameter of 0.8 mm have been carried out. The size of the powders, their shape, chemical composition, microstructure and microhardness have been investigated.
Modification of a Fur Semi-finished Sheepskins by Radio Frequency Plasma in an Inert Gas Medium
Authors: Pankova E A , Sharifullin F S , Rakhmatullina G R , Shagivalieva R R , Zheltukhin V S
Published: June 2021

It is established that radio frequency plasma treatment of a finished fur semi-finished sheepskins in an inert gas medium does not lead to chemical changes, but it provides conformational changes in the structure of the fur material, thereby allowing to regulate its sorption characteristics (from the most hydrophobic to the most hydrophilic) by varying the parameters of plasma treatment.
Analysis of the effect of combustion chamber length on the gas oscillations characteristics
Authors: Malakhov A O , Larionov V M , Khalilov A R , Nazarychev S A , Konstantinov N V
Published: June 2021

In this paper, the case of the influence of a change in the length of the vortex combustion chamber on the amplitude-frequency characteristics of gas oscillations is considered. Experimental data were obtained, on the basis of which the graphs of the dependence of the amplitude and frequency of the combustion chamber on the excess air ratio were received.
Gas discharge combustion with a liquid tetrachloride electrode
Authors: Kashapov R N , Kashapov L N , Kashapov N F , Sergeev P V
Published: June 2021

Titanium powders are widely used in selective laser melting and electron beam melting technologies to create medical implants. However, powders of a certain fractional composition are suitable for these purposes. A gradual increase in the volume of manufactured products requires the creation of new cheap methods for obtaining metal powders. Plasma-chemical synthesis in titanium tetrachloride solution can be one of the new methods for producing powders. A feature of this method is the use of a gas discharge with liquid electrodes, as a liquid electrode and is a titanium tetrachloride solution. The aim of the work was to study the possibility of obtaining a metal powder and its rapid cooling in a liquid. The question of the influence of the discharge parameters on the formation of metal particles remains open. In this work, a study of a gas discharge with liquid electrodes under the conditions of anode and cathode modes is carried out. A gas discharge between a liquid electrolyte and a metal electrode is experimentally investigated in the voltage range of 300-1000V. The conditions under which a stable discharge column is formed and a metal powder is formed are established. The regularities of the change in the I–V characteristic of the discharge are determined depending on the interelectrode distance.
The use of ultrasound to produce metallic powder in the plasma discharge electrolyte
Authors: Kashapov R N , Kashapov L N , Kashapov N F , Sergeev P V
Published: June 2021

In this work, a new process of plasma-electrolyte sputtering under the action of ultrasonic vibration is proposed, which makes it possible to obtain a finely dispersed metal powder with an average particle diameter of about 100 μm. The process involves irradiation with a high-power continuous laser on a consumable metal substrate vibrating at an ultrasonic frequency. The burning of a gas discharge around the vibrating electrode causes the surface to melt and small droplets are ejected. Preliminary results of spraying stainless steel 12X18H9T with a discharge power of 800 W and an ultrasonic vibration frequency of 20 kHz are presented. Vibration displacement does not significantly affect average particle size and size distribution according to capillary wave spray theory. The microstructure of the larger atomized particles exhibits a fine dendritic structure on the surface and shrinkage porosity at the center of the particles, indicating multiple surface nucleation for solidification.
Internal variability and temperature scaling of future sub-daily rainfall return levels over Europe
Authors: Poschlod Benjamin , Ludwig Ralf
Published: June 2021

The range of sub-daily extreme precipitation due to internal variability is quantified within the single model initial-condition large ensemble featuring 50 members of the Canadian regional climate model, version 5 (CRCM5) under the high-emission scenario representative concentration pathway 8.5. Ten-year return levels of sub-daily precipitation are calculated for three future periods (2010–2039, 2040–2069, 2070–2099) and hourly to 24-hourly aggregations over a European domain. The return levels are found to increase by 4%–8% for every future 30 year period averaged for the study area, where short-duration rainfall intensities increase to a greater extent than longer-duration rainfall intensities. The ranges between the median of the 50 members and the 5th and 95th quantile amount to −15.6%–19.3%, −16.0%–20.1%, and −16.5%–20.9% for the near, mid and far future, respectively. It is also shown that the scaling of the precipitation increase with temperature (Clausius–Clapeyron scaling) exhibits substantial variations between the 50 CRCM5 members at regional aggregations. These findings illustrate the large impact of internal variability on the uncertainty of extreme precipitation return level estimates. Here, regions of significant changes are identified, where future median extreme precipitation exceeds the 95th quantile of the reference period (1980–2009). These regions are located in northern Europe, central Europe and the eastern part of the Mediterranean.
On a nonlinear Volterra integrodifferential equation involving fractional derivative with Mittag-Leffler kernel
Authors: Caraballo Tomás , Ngoc Tran Bao , Tuan Nguyen Huy , Wang Renhai
Published: June 2021

In this paper, we study a nonlinear time-fractional Volterra equation with nonsingular Mittag-Leffler kernel in Hilbert spaces. By applying the properties of Mittag-Leffler functions and the method of eigenvalue expansion, we give a mild solution of our problem. Our main tool here is using some Sobolev embeddings.
A Tale of Two Countries: Divorce in England and Prussia, 1670–1794
Authors: Lettmaier Saskia
Published: June 2021

Why did two leading European countries (Prussia and England), which at first sight appeared to have much in common, enact radically different divorce legislation during the eighteenth century? This Article takes a close look at each country’s reforms, their legislative history, and their likely effects in an effort to tease out what motives lay behind them. And by connecting the legal changes to the countries’ sociopolitical and intellectual structures, it goes on to explain why the reforms were so different. The Article’s findings are relevant not only for the history of the law of divorce, but also for the broader issue of what forces play a role in the evolution of the law. Today, few would doubt the proposition that there are social and ideological “causes” of legal development. However, what these causes are and in what combination they have to be present for a legal change to occur are questions that are rarely examined in any detail.
Democratizing the Op-Ed: Anti-Caste Counterpublics & the Mainstream News
Authors: Rao Pallavi
Published: June 2021

How have anti-caste commentators in mainstream English news in India participated in media discourses on caste? In this article, I draw attention to a digital space of contestation where anti-caste writings have gained prominence—the opinion column in online news platforms. I am particularly interested in how anti-caste writings, bearing the imprint of authorial agency, have emerged in the digital sphere through structural linkages between caste, linguistic formations, and formal politics. The article considers how and in what ways historically marginalized Dalit-Bahujan commentators and their news public’s concerns are rendered visible within the space of mainstream digital news.
Maternal Bisphenol A (BPA) Exposure Alters Cerebral Cortical Morphogenesis and Synaptic Function in Mice
Authors: Lee Chang Youn , Hyun Sung-Ae , Ko Moon Yi , Kim Hye Ryeong , Rho Jaerang , Kim Kee K , Kim Woo-Yang , Ka Minhan
Published: June 2021

Early-life exposure to bisphenol A (BPA), synthetic compound used in polycarbonate plastic, is associated with altered cognitive and emotional behavior later in life. However, the brain mechanism underlying the behavioral deficits is unknown. Here, we show that maternal BPA exposure disrupted self-renewal and differentiation of neural progenitors during cortical development. The BPA exposure reduced the neuron number, whereas it increased glial cells in the cerebral cortex. Also, synaptic formation and transmission in the cerebral cortex were suppressed after maternal BPA exposure. These changes appeared to be associated with autophagy as a gene ontology analysis of RNA-seq identified an autophagy domain in the BPA condition. Mouse behavioral tests revealed that maternal BPA caused hyperactivity and social deficits in adult offspring. Together, these results suggest that maternal BPA exposure leads to abnormal cortical architecture and function likely by activating autophagy.
Mathematical Modeling to Inform Vaccination Strategies and Testing Approaches for Coronavirus Disease 2019 (COVID-19) in Nursing Homes
Authors: Kahn Rebecca , Holmdahl Inga , Reddy Sujan , Jernigan John , Mina Michael J , Slayton Rachel B
Published: June 2021

Background

Nursing home residents and staff were included in the first phase of coronavirus disease 2019 vaccination in the United States. Because the primary trial endpoint was vaccine efficacy (VE) against symptomatic disease, there are limited data on the extent to which vaccines protect against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the ability to infect others (infectiousness). Assumptions about VE against infection and infectiousness have implications for changes to infection prevention guidance for vaccinated populations, including testing strategies.

Methods

We use a stochastic agent-based Susceptible-Exposed-Infectious (Asymptomatic/Symptomatic)-Recovered model of a nursing home to simulate SARS-CoV-2 transmission. We model 3 scenarios, varying VE against infection, infectiousness, and symptoms, to understand the expected impact of vaccination in nursing homes, increasing staff vaccination coverage, and different screening testing strategies under each scenario.

Results

Increasing vaccination coverage in staff decreases total symptomatic cases in the nursing home (among staff and residents combined) in each VE scenario. In scenarios with 50% and 90% VE against infection and infectiousness, increasing staff coverage reduces symptomatic cases among residents. If vaccination only protects against symptoms, and asymptomatic cases remain infectious, increased staff coverage increases symptomatic cases among residents. However, this is outweighed by the reduction in symptomatic cases among staff. Higher frequency testing—more than once weekly—is needed to reduce total symptomatic cases if the vaccine has lower efficacy against infection and infectiousness, or only protects against symptoms.

Conclusions

Encouraging staff vaccination is not only important for protecting staff, but might also reduce symptomatic cases in residents if a vaccine confers at least some protection against infection or infectiousness.