Shape Of Profile Research Articles

Continuous tunability of refractive index contrast in LiNbO3 optical waveguides fabricated by high-vacuum vapor-phase proton exchange

The actual techniques allowing the fabrication of waveguides in lithium niobate are not able to satisfy one of the demands of modern integrated photonics namely the well-controlled tunability of index contrast over a large range of values (from high-index contrast to low index contrast). This paper presents a simple and reliable method allowing well-controlled index contrast tunability between high-index contrast (Δne = 0.1) and low-index contrast (Δne = 0.035) while benefiting from the optical nonlinearity of LiNbO3 waveguides fabricated using HiVac-VPE technique. The study involves both planar and channel lithium niobate waveguides. The planar waveguides subjected to an annealing process for 1 to 5.5 h, are characterized before and after the thermal treatment, in order to determine the index contrast evolution and to analyze the changes of index profile shapes. Furthermore, it is found that the index profile after annealing is fitted by an exponential function different from Gaussian fit found in well-known Annealed Proton Exchange technique. Additionally, the index contrast dependence of the annealing time is also fitted by an exponential function. Channel waveguides, fabricated in the same condition, were designed for single-mode propagation at telecom wavelength. After characterization, the best of investigated annealed channel waveguides exhibits propagation losses around 1.5 ± 0.1 dB/cm. Therefore, the presented technique offers the opportunity for customization of photonics circuitry, scalability of integrated photonics platform, enhancement of non-linear optical efficiency at the single photon level for quantum information platforms.

Accurate space-based NOx emission estimates with the flux divergence approach require fine-scale model information on local oxidation chemistry and profile shapes

Abstract. The flux divergence approach (FDA) is a popular technique for deriving NOx emission estimates from tropospheric NO2 columns measured by the TROPOspheric Monitoring Instrument (TROPOMI) satellite sensor. An attractive aspect of the FDA is that the method simplifies three-dimensional atmospheric chemistry and transport processes into a two-dimensional (longitude–latitude) steady-state continuity equation for columns that balances local NOx emissions with the net outflow and chemical loss of NOx. Here we test the capability of the FDA to reproduce known NOx emissions from synthetic NO2 column retrievals generated with the LOTOS-EUROS chemistry transport model over the Netherlands at high spatial resolution of about 2×2 km during summer. Our results show that the FDA captures the magnitude and spatial distribution of the NOx emissions to high accuracy (absolute bias <9 %), provided that the observations represent the NO2 column in the boundary layer, that wind speed and direction are representative for the boundary layer (PBL) column, and that the high-resolution spatiotemporal variability of the NO2 lifetimes and NOx:NO2 ratio is accounted for in the inversion instead of using single fixed values. The FDA systematically overestimates NOx emissions by 15 %–60 % when using tropospheric NO2 columns as the driving observation, while using PBL NO2 columns largely overcomes this systematic error. This merely reflects the fact that the local balance between emissions and sinks of NOx occurs in the boundary layer, which is decoupled from the NO2 in the free troposphere. Based on the recommendations from this sensitivity test, we then applied the FDA using observations of NO2 columns from TROPOMI, corrected for contributions from free-tropospheric NO2, between 1 June and 31 August 2018. The NOx emissions derived from the default TROPOMI retrievals are biased low over cities and industrialized areas. However, when the coarse 1×1° TM5-MP NO2 profile used in the retrieval is replaced by the high-resolution profile of LOTOS-EUROS, the TROPOMI NOx emissions are enhanced by 22 % and are in better agreement with the inventory for the Netherlands. This emphasizes the importance of using realistic high-resolution a priori NO2 profile shapes in the TROPOMI retrieval. We conclude that accurate quantitative NOx emissions estimates are possible with the FDA, but they require sophisticated, fine-scale corrections for both the NO2 observations driving the method and the estimates of the NO2 chemical lifetime and NOx:NO2 ratio. This information can be obtained from high-resolution chemistry transport model simulations at the expense of the simplicity and applicability of the FDA.

FEASTS: Radial Distribution of H i Surface Densities Down to 0.01 M⊙ pc−2 of 35 Nearby Galaxies

Abstract We present the H i surface density (ΣH i ) radial distributions based on total-power H i images obtained by FAST in the FEASTS program, for 35 galaxies with inclinations lower than 72°. We derive the H i radius R 001, which is the radius for the 0.01 M ⊙ pc−2 (~1018.1 cm−2) isodensity level, 100 times deeper than the 1 M ⊙ pc−2 level previously commonly used to measure R 1. The profile shapes show a large diversity at a given radius in units of kpc, group virial radius, and R 1, but they align more tightly with the radius normalized by R 001. The universal H i profile has a scatter of ~0.2 dex and a scale length of ~0.11R 001 in the outer region. We derive a new R 001–M H i relation, which has a scatter of 0.03 dex and a similar slope of ~​​​​​​0.5 to the previously known R 1–M H i relation. Excluding strongly tidal-interacting galaxies, the ratio R 001/R 1 (anti)correlates strongly and significantly with the H i-to-stellar mass ratio and specific star formation rate, but not with the stellar mass, M H i , dark matter mass, or star formation rate. The strongly tidal-interacting galaxies tend to show deviations from these trends and have the most flattened profiles. These results imply that, in the absence of major tidal interactions, physical processes must cooperate so that ΣH i distributes in a self-similar way in the outer region down to the 0.01 M ⊙ pc−2 level. Moreover, they may drive gas flows in such a way that H i-richer galaxies have H i disks that not only extend further but also transport H i inward more efficiently from R 001 to R 1.

Visualizing gaussian-chain like structural models of human α-synuclein in monomeric pre-fibrillar state: Solution SAXS data and modeling analysis.

Here, using small angle X-ray scattering (SAXS) data profile as reference, we attempted to visualize conformational ensemble accessible prefibrillar monomeric state of α-synuclein in solution. In agreement with previous reports, our analysis also confirmed that α-synuclein molecules adopted disordered shape profile under non-associating conditions. Chain-ensemble modeling protocol with dummy residues provided two weighted averaged clusters of semi-extended shapes. Further, Ensemble Optimization Method (EOM) computed mole fractions of semi-extended "twisted" conformations which might co-exist in solution. Since these were only Cα traces of the models, ALPHAFOLD2 server was used to search for all-atom models. Comparison with experimental data showed all predicted models disagreed equally, as individuals. Finally, we employed molecular dynamics simulations and normal mode analysis-based search coupled with SAXS data to seek better agreeing models. Overall, our analysis concludes that a shifting equilibrium of curved models with low α-helical content best-represents non-associating monomeric α-synuclein.

Velocity shift of a C IV broad absorption line in quasar SDSS J145229.08+093204.9

We present the observation of a velocity shift in the broad absorption line (BAL) of C IV ion in quasar SDSS J145229.08+093204.9 (hereafter J1452+0932).This quasar exhibits three distinct BAL systems, designated as systems A, B, and C. Notably, system A, which possesses the highest velocity of approximately -23,000 demonstrates a velocity shift of -1097 in its C IV ion over a rest-frame period of approximately 1.7 years. To elucidate the nature of these variations, we conducted a comprehensive analysis focusing on the variation situation, location, ionisation state, and profile shape of the three BAL systems in J1452+0932. Our findings reveal that system A is situated closer to the central source compared to systems B and C. Furthermore, system A exhibits higher velocities, higher ionisation states, and smoother profile morphologies. These characteristics collectively suggest that the outflow generating system A is situated in a particularly extreme environment and experiences more pronounced impacts from background radiation energy than systems B and C. Consequently, we postulate that the observed velocity shift in system A may signify an actual line-of-sight acceleration of the outflow, induced by the radiation pressure emanating from the central source. Specifically, this scenario could occur if our line of sight intersects an outflow at a location where it is undergoing acceleration towards its terminal outflow velocity, or if a previously coasting outflow is undergoing renewed acceleration.

Controllable anisotropic wettability behaviours of droplets by varying profile stripe structures

Abstract Anisotropic wettability of bionic structures is often achieved through anisotropic patterns, so the parameters of that are key to managing surface wettability behaviours. In this work, we fabricate three kinds of one-dimensional (1D) stripe structures with distinct profile shapes for studing the method of controlling anisotropic wettability behaviours of water droplets. By controlling their profiles and depths, the anisotropic wettability of stripes can be effectively managed and mitigated. Even with the same stripe periods, we can achieve two opposing wetting effects, namely isotropic hydrophobicity and anisotropic hydrophilicity. The experiments show that the π-shaped stripes possess isotropic superhydrophobicity, and their adhesion force to water droplets in the direction perpendicular to the groove is approximately ten times that in the parallel direction. Meanwhile, the willow-leaf-shaped stripes show anisotropic hydrophilic properties and good ductility to water droplets. Taking advantage of inductively coupled plasma-reactive ion etching (ICP-RIE) with a low undercut, this method provides a novel perspective on the design of interfaces for droplet manipulation, pick-and-place applications, and the localised control of reactions.

Research and Application of Personalized PDC Bits for Longmaxi Formation in Changning, Sichuan Basin

The Longmaxi Formation in the Changning Block of the Sichuan Basin has a large reservoir thickness and is a high-quality shale for the main shale gas bearing target layer. However, problems such as high rock strength, high drillability level, and large horizontal drilling length in the Longmaxi Formation have led to rapid failure of the drill bit and slow ROP (Rate of Penetration). Research has found that almost all PDC drill bits used in this formation are foreign products, and the drill bits have failure due to core and external cone cutter impact. Therefore, in order to achieve the localization of Longmaxi formation drill bits and the goal of ‘one trip drilling’, personalized design and application of PDC drill bits are carried out. The rock mechanics property parameters of Changning Longmaxi Shale were obtained by obtaining rock samples on the spot and conducting rock mechanics property experiments. To solve the problem of external cone failure of foreign drill bits, the first generation of axe shaped PDC drill bits targeting the Longmaxi Formation were designed and developed. The average drilling speed of the first generation PDC drill bit is 7.4m/h, which exceeds most PDC drill bits abroad, but is still lower than the highest average drilling speed of foreign drill bits. In order to further improve the bit's invasion ability and directional stability, the profile shape and cutter arrangement of the first generation PDC bit were further optimized, and drilling simulation was conducted. After optimization, the bit's invasion ability and directional stability increased. After optimization, the drill bit footage was 2005m, with an average drilling speed of 10.77 m/h, which was 45% higher than before optimization, far exceeding the highest drilling speed abroad, and achieving the goal of ‘ne trip drilling’ for long horizontal sections. The successful application of this drill bit provides in-depth understanding and experience for increasing drilling speed in the Longmaxi Formation in Changning.

Dynamic Response and Lubrication Performance of Spur Gear Pair Under Time-Varying Rotation Speeds

The rotation speed directly influences the vibration and lubrication behaviors of gear pairs, but studying the effects of time-varying rotation speeds during their operation poses substantial challenges. The present work proposed an approach to analyzing the dynamic response and lubrication performance of spur gear pairs under time-varying rotation speeds. A single-degree-of-freedom torsional dynamics model was established to capture the vibration responses and meshing forces of a gear pair, with the meshing stiffness modulated by the time-varying rotation speed. Additionally, a transient elastohydrodynamic lubrication model of the gear system was proposed to obtain the pressure pro-file and film shape, incorporating the effects of time-varying rotation speeds. Three types of time-varying rotation speeds were investigated: acceleration, deceleration, and oscillation. The results reveal that the time-varying rotation speed induces chaotic motion of the gear system, resulting in significant changes in the dynamic meshing force, entrainment velocity, and curvature radius of the gear pair compared to those in constant-speed scenarios. The lubrication performance under time-varying rotation speeds also shows diverse dynamic characteristics, highlighting significant differences from that observed under a constant rotation speed. These insights contribute to a more comprehensive understanding of gear dynamics under realistic operating conditions, enhancing gears’ performance and reliability in practical applications.

Ceftazidime-avibactam (CAZ-AVI) pharmacokinetics in critically ill patients undergoing continuous venovenous hemodiafiltration (CVVHDF)

To investigate the pharmacokinetics (PK) of ceftazidime-avibactam (CAZ-AVI) in critically ill patients undergoing continuous venovenous hemodiafiltration (CVVHDF), and compare with a general phase III trial population. A prospective PK study was conducted in critically ill patients who received CVVHDF for acute kidney injury, treated with CAZ-AVI (1000/250 mg or 2000/500 mg q8h). Plasma and CVVHDF-circuit samples were collected to determine CAZ-AVI concentrations. Individual PK parameters at steady-state were estimated using non-compartmental analysis. For visual comparison, plasma concentrations from CVVHDF patients were overlaid with simulated data from patients not receiving CVVHDF based on previously developed population PK models. A total of 35 plasma samples and 16 CVVHDF-circuit samples were obtained from four patients, with two patients sampled on two separate occasions. Median total clearance and volume of distribution were 4.54 L/h and 73.2 L for CAZ and 10.5 L/h and 102 L for AVI, respectively. Median contribution of CVVHDF to total clearance was 19.8% for CAZ and 5.3% for AVI. Observed CAZ-AVI PK profiles were generally within the 90% confidence interval of model predictions, but the observed concentrations were notably lower early (0-2 h) and higher later (4-8 h) in the dosing interval, suggesting a higher volume of distribution. These results suggest that the CAZ-AVI dose regimens used in this study can be applicable in critically ill patients undergoing CVVHDF, despite the different shape of the PK profiles observed in this population. Further research with a larger patient cohort is warranted to validate and refine these findings.

Nanoparticle adhesion at liquid interfaces.

Nanoparticle adhesion at liquid interfaces plays an important role in drug delivery, dust removal, the adsorption of aerosols, and controlled self-assembly. However, quantitative measurements of capillary interactions at the nanoscale are challenging, with most existing results at the micrometre to millimetre scale. Here, we combine atomic force microscopy (AFM) and computational simulations to investigate the adhesion and removal of nanoparticles from liquid interfaces as a function of the particles' geometry and wettability. Experimentally, AFM tips with controlled conical geometries are used to mimic the nano-asperities on natural nanoparticles interacting with silicone oil, a model liquid for many engineering applications including liquid-infused surfaces. Computationally, continuum modelling with the Surface Evolver software allows us to visualise the interface configuration and predict the expected force profile from energy minimisation. Quantitative agreement between the experimental measurements and the computational simulations validates the use of continuum thermodynamics concepts down to the nanoscale. We demonstrate that the adhesion of the nanoparticles is primarily controlled by surface tension, with minimum line tension contribution. The particle geometry is the main factor affecting the length of the capillary bridge before rupture. Both the particle geometry and liquid contact angle determine the shape of the adhesion force profile upon removal of the particle from the interface. We further extend our simulations to explore more complex geometries, rationalising the results from experiments with imperfect AFM tips. Our results could help towards the design of smart interfaces, for example, able to attract or repel specific particles based on their shape and chemistry.

The Role of Local Acceleration and Radial Diffusion in Multi‐MeV Electron Flux Enhancements

AbstractDuring the Van Allen Probes era, several multi‐MeV (>4 MeV) electron flux enhancements were observed. The cause of electron acceleration up to multi‐MeV remains an ongoing science topic. In this study, we focus on examining the relationship between phase space density (PSD) radial profile shapes and the occurrence of multi‐MeV electron flux enhancement events. This will determine which process (local acceleration or radial diffusion) is dominant in producing multi‐MeV electron flux enhancements at a specific L*. Growing peaks in PSD radial profiles are associated with the local acceleration (i.e., a wave‐particle interaction) of multi‐MeV electrons. For each growing peak in PSD, we determined the L* where the local acceleration occurs for each respective electron energy. Similarly, we also identify which PSD profiles are related to acceleration via radial diffusion profiles. Both sets of profiles are compared with the Van Allen Probe‐A observed multi‐MeV electron flux enhancements. Results show that both mechanisms (local acceleration and radial diffusion) can facilitate multi‐MeV electron acceleration, however each mechanism has a preferable L* region where it is the dominant acceleration process.

The Effect of Outflow Launching Radial Efficiency of Accretion Disk on the Shape of Emission-Line Profiles

This paper presents a preliminary investigation into the influence of radial behavior of disk outflow on the structure and dynamics of the broad line region (BLR) in active galactic nuclei (AGNs), with an emphasis on how the mass ejection rate contributes to shaping the broad emission-line profiles. Specifically, we analyze how varying the radial efficiency of mass loss from accretion disks, driven by radiative dust-based mechanisms, contributes to the distribution of material in the BLR. By exploring different radial scenarios of disk mass loss behavior, we uncover connections between outflow radial efficiency and emission line profiles, particularly for lowly ionized lines. Our findings reveal that while the observed shape of broad emission lines is partially influenced by the radial behavior of the disk outflow, it ultimately depends more critically on the physical conditions of the clouds and the specific approach adopted regarding the emissivity for their contribution to the line formation.

Bio-Optical Response of Phytoplankton and Coloured Detrital Matter (CDM) to Coastal Upwelling in the Northwest South China Sea

To examine the bio-optical response to coastal upwelling, we measured inherent optical properties (IOPs) and biogeochemical parameters simultaneously off Hainan Island in the northwest part of the South China Sea (SCS) during late summer 2013. Bio-optical relationships between IOPs and phytoplankton were used for calculating vertical profiles of the total chlorophyll a concentration (Chl-a) and the absorption by coloured detrital matter (CDM). These bio-optical properties, which showed distinct horizontal and vertical distributions across the continental shelf, were strongly influenced by upwelling processes, as well as the shelf topography. Phytoplankton biomass and CDM absorption in surface waters showed much higher values along the coast, with their spatial distributions related to topographic variability. Vertical distributions of phytoplankton were characterised by a subsurface chlorophyll maximum (SCM) layer. The strongest SCM (Chl-a = 4.22 mg m−3) was observed at 24 m depth in coastal waters near the northeast cape of Hainan Island. The depth of the SCM varied between 16 and 60 m at different stations, appearing to coincide with the isotherm of 22 °C. The SCM depth was inversely correlated with the magnitude of the SCM. Different shapes of Chl-a profiles were observed, which suggested that the vertical distributions of phytoplankton biomass were driven by different environmental factors. Elevated concentrations of CDM were mainly observed near the bottom, which suggest that the benthic nepheloid layer may be an important source of detrital material. The relationship between the absorption coefficient of CDM at 443 nm, aCDM(443), and Chl-a exhibited distinct differences between waters in upper ocean and in bottom layers, with the threshold depth being modulated by shelf topography. Our results highlight the utility of bio-optical observations with high resolution for better understanding the coupling between physical forcing and biogeochemical variability.

Shape of the Doppler Sonographic Systolic Blood Flow Profile of the Pulmonary Artery of Healthy Racing Pigeons and the Influence of Anesthesia.

There is scant information available about the blood flow of the pulmonary artery in avian cardiology. In human medicine, the shape of the Doppler sonographic blood flow profile of the pulmonary artery can be used to access the pressure conditions of the right heart. With this background, this study focused on the examination of the acceleration and deceleration phase of the pulsed-wave Doppler flow profile of the pulmonary artery of healthy racing pigeons. The results showed a significant difference between the pulmonary artery and aorta. The Doppler flow profile of the aorta was characterized by a short acceleration phase; however, the pulmonary flow profile revealed an acceleration similar to that of the deceleration phase. Neither profile changed considerably under the influence of heart rate changes and anesthesia with isoflurane. A negative correlation of the pulmonary acceleration phase with the left diastolic A wave and the systolic pulmonary blood flow velocities could be found. This indicates the influence of pressure changes in the heart on the flow profiles. The results of this study allow for the use of the shape of the Doppler sonographic blood flow profile of the pulmonary artery in the assessment of cardiovascular diseases in avian medicine, especially in racing pigeons.

Yielding Behaviour of Steel Beams as a Result of the Shape of the Strands' Fixity Profile

Yielding Behaviour of Steel Beams as a Result of the Shape of the Strands' Fixity Profile

Measurement of bone deformation and insertion torque during dental implant installation.

Insertion of dental implants causes bone deformation and induces residual bone compression stress, which can lead to implant failure if the bone loss threshold is exceeded. The current literature about bone stress is restricted to computer simulations and implant primary stability measurements after installation. This work measures the torque and deformation during implant insertion testing. The aim of this work was to analyze the influence surface treatment, thread profile, body shape and the presence of microthreads in the neck on the primary stability, bone deformation and residual stress during dental implants insertion. The insertion torque and resonance frequency analysis (RFA) are the main technique used to measure the primary stability of dental implants. Five models of dental implants with different surface treatments (machined and acid etching), thread profiles (triangular and trapezoidal) and body shapes (cylindrical and conical) were inserted in synthetic bone blocks (polyurethane) with a density of 30 PCF (0.48g/cm³) compatible with the D2 bone. The insertion torque was quantified by a digital torque driver. Strain gauge extensometry technique was used to measure bone deformation during implant insertion. The bone deformation and torque increase as the number of implants turns insertion increases. Dental implant with trapezoidal thread profile needs higher insertion torque than triangular threads. Implants with a conical shape require higher insertion torque than cylindrical ones. The bone stress induced by machined implant insertion exceeded the bone's mechanical resistance, causing cracks. Conical implants showed better performance than cylindrical ones. The implants with a trapezoidal thread and those with a conical body induce greater insertion torque. Comparing the mechanical behavior, it was found that the machined implants had the worst performance in terms of stress distribution in the synthetic bone, resulting in cracks in the specimen during insertion. Implants with trapezoidal threads and those with a conical body induce insertion torque and bone compression stresses that do not harm osseointegration. Excessive deformations in the peri-implant bone led to bone necrosis and implant failure. Thus, the surgeons must analyze the influence of surface treatment, thread profile, and body shape on the osseointegration process.

A Fault Displacement Model Based on the FDHI Database

Fault displacement models are a key component of probabilistic fault displacement hazard analysis (PFDHA), providing the displacement probability density function. We present a new fault displacement model developed using the comprehensive database compiled for the Fault Displacement Hazard Initiative (FDHI) project. The model predicts the total net displacement across multi-stranded surface ruptures as a function of moment magnitude and position along the rupture length. We provide separate models for strike-slip, reverse, and normal faulting. A bilinear magnitude scaling is used to capture the steeper magnitude scaling for smaller magnitudes observed in the data for strike-slip and normal faulting. The scaling for reverse faulting approaches log-linear but still uses a bilinear form. Our flexible location scaling functional form captures the asymmetric profile shapes common in the data for dip-slip events and more symmetrical elliptical profiles in the strike-slip data. We applied a Box-Cox transformation to the displacement dataset so that the data resemble a normal distribution, which allows the transformed displacement to be conveniently modeled as normally distributed. Between- and within-event aleatory variability are modeled separately. All model parameters are estimated using Bayesian regression, which allows within-model epistemic uncertainty to be quantified. Compared with earlier models, the new model produces less aleatory variability and smaller upper-tail displacements for magnitudes greater than about 6.5 for all styles of faulting and all locations along the rupture. Data dispersion at the rupture end-points in the strike-slip and reverse faulting resulted in large aleatory variability. Large aleatory variability for smaller magnitude strike-slip and normal events is driven by a lack of data at smaller magnitudes. The use of a large, high-quality database and advanced statistical modeling techniques in our new model provides improved predictions of fault displacement compared with earlier models.

The influence of the constructive shapes of aluminum profiles on impact phenomena

The influence of the constructive shapes of aluminum profiles on impact phenomena

Experimental study on metallic impurity behavior with boronization wall conditioning in EAST tokamak

Experimental study on metallic impurity behavior with boronization wall conditioning in EAST tokamak

Influence of the Shape of the Pump Current Profile on Stabilization of the Dynamics of a Broad-Area Vertical-Cavity Surface-Emitting Laser

Influence of the Shape of the Pump Current Profile on Stabilization of the Dynamics of a Broad-Area Vertical-Cavity Surface-Emitting Laser