High-resolution Experiments Research Articles

Experimental and numerical investigation of the transition progress of strut-induced wakes in the supersonic flows

Strut serves as an effective and robust flameholder in a scramjet combustor, and the resultant wakes have a great impact on the fuel mixing and flame stabilization. Present work focuses on the non-reactive flow induced by strut without fuel injection, removing the effect of chemical reactions on turbulence. To investigate the transition process of turbulent wakes, both high-resolution experiments and numerical simulations are conducted. An advanced optical measurement technique is adopted to visualize the flow structures in different Mach conditions, and to disclose the compressible effect on the shear layer. Experimental results indicate that the scale of turbulent vortices decreases and the transition becomes difficult with the decline of Reynolds number in the cases with the same total temperature and pressure. Evidently, the viscous effect gets weakened for the supersonic flow with a high Reynolds number, giving rise to large scale vortex streets. On this basis, the intrinsic mechanism that governs the instability of shear layer is investigated by large eddy simulation. The strut-induced wakes can be divided into three parts, namely the recirculation zone, the transition zone and the downstream turbulent zone. A type of Kelvin-Helmholtz instability produced by the interactions of the reattachment shock and shear stress, should be responsible for the generation of the initial streamwise vortices during the transition process of shear layer. Thus, the flow instability rapidly grows as a form of nonlinear, magnifies, and changes the mean velocity profile of the shear layer, leading to its transition from laminar state to turbulence. Finally, the influence of turbulence on the temporal and spatial evolution of the vortices in the wakes is analyzed in deep. The upstream turbulent fluctuations facilitate the occurrence of transition process, and promote to generate larger scale spanwise vortex streets. Present work can help us understand the flow dynamics of turbulent wakes in a strut-stabilized scramjet combustor.

Component-Aware High-Resolution 3D Object Reconstruction

<p indent="0mm">The computational cost of the voxel-based 3D object reconstruction grows cubically with the increase of the resolution. To address this problem, the proposed component-aware 3D object reconstruction method decomposes a 3D object into several components to reconstruct the 3D object by predicting and assembling a series of components, which transforms the high-resolution 3D object reconstruction into a series of low-resolution component reconstruction. The proposed method predicts the positions of all components using a component position prediction module. Then the geometric and appearance feature of a component are fused into a joint feature with a component feature extraction module. The joint feature is utilized by a component shape reconstruction module to predict the geometry of components. Finally, all components are assembled into a high-resolution 3D object with the guidance of their positions. Experiments are performed on ShapeNet dataset using an NVIDIA 1080 Maxwell GPU with 12 GB of memory. The comparison methods include an octree-based high-resolution reconstruction method, a LSTM-based low-resolution reconstruction method and a baseline method using encoder-decoder architecture. The results of high-resolution reconstruction experiment demonstrate that the component-aware 3D reconstruction method achieves a satisfactory 3D reconstruction accuracy with a low computational cost. In the low-resolution reconstruction experiment, the proposed method also performs better and the average accuracy in 13 categories reaches 0.618.

Reanalyzes for 42–51Ca scattering on a 12C target at 280 MeV/nucleon based on chiral [formula omitted] folding mode with Gogny-D1S Hartree–Fock–Bogoliubov densities

Background:In the previous paper, we predicted reaction cross sections σR for 40−60,62,64Ca+12C scattering at 280 MeV/nucleon, using the chiral g-matrix folding model with the densities calculated with the Gogny-D1S Hartree–Fock–Bogoliubov (GHFB) with and without the angular momentum projection (AMP), since Tanaka et al. measured interaction cross sections σI(≈σR) for 42−51Ca in RIKEN and determined neutron skin rskin(RIKEN) using the optical limit of the Glauber model with the Woods–Saxon densities. Purpose:Our purpose is to reanalyze the rskin from the σI using the chiral g-matrix folding model. Our analysis is superior to theirs, since the chiral g-matrix folding model (the GHFB and GHFB+AMP densities) is much better than the optical limit of the Glauber model (the Woods–Saxon densities). Methods:Our model is the chiral g-matrix folding model with the densities scaled from the GHFB and GHFB+AMP densities. Results:We scale the GHFB and GHFB+AMP densities so that the σR of the scaled densities can agree with the central values of σI under the condition that the proton radius of the scaled proton density equals the data determined from the isotope shift based on the electron scattering. The rskin thus determined are close to their results rskin42−51(RIKEN), except for 48Ca. For 48Ca, our value rskin48 is 0.105 ± 0.06 fm, while their value is rm48(RIKEN)=0.146±0.06 fm. We then take the weighted mean and its error of our result rskin48(σI)=0.105±0.06 fm and the result rskin48(E1pE)=0.17±0.03 fm of the high-resolution E1 polarizability experiment (E1pE). Our final result is rskin48=0.157±0.027 fm. Conclusion:Our conclusion is rskin48=0.157±0.027 fm for 48Ca. For 42−47,49−51Ca, our results on rskin are similar to theirs. Our result for 48Ca is related to CREX.

Electronic structure of (MePh3P)2[NiII(bdtCl2)2]·2(CH3)2SO and (MePh3P)[NiIII(bdtCl2)2] (bdtCl2 = 3,6-dichlorobenzene-1,2-dithiolate)

High-resolution X-ray diffraction experiments, theoretical calculations and atom-specific X-ray absorption experiments were used to investigate two nickel complexes, (MePh3P)2[NiII(bdtCl2)2]·2(CH3)2SO [complex (1)] and (MePh3P)[NiIII(bdtCl2)2] [complex (2)]. Combining the techniques of nickel K- and sulfur K-edge X-ray absorption spectroscopy with high-resolution X-ray charge density modeling, together with theoretical calculations, the actual oxidation states of the central Ni atoms in these two complexes are investigated. Ni ions in two complexes are clearly in different oxidation states: the Ni ion of complex (1) is formally NiII; that of complex (2) should be formally NiIII, yet it is best described as a combination of Ni2+ and Ni3+, due to the involvement of the non-innocent ligand in the Ni—L bond. A detailed description of Ni—S bond character (σ,π) is presented.

Electron-molecule collisions with explicit rovibrational resolution at MRCI level and using even tempered basis sets.

A method for calculating the generalized oscillator strengths (GOSs) and differential cross section (DCS) with vibration and rotation resolution is presented. The importance of accounting for the rotational contribution is to be emphasized since it has not previously been considered in GOS calculations. Although largely neglected due to its small effect on various properties, the rotational resolution proved to be fundamental in the study of certain phenomena, such as the interference between rotational states in a molecule. As the general goal of this work is to obtain theoretical values comparable to high resolution experiments, special care was taken on the calculation of the electronic part of the scattering amplitude, particularly in what concerns the choice of the atomic basis set. Accordingly, even-tempered basis sets have proved to lead to good results. The helium atom was taken as a model system for this aspect of the problem. Then, GOS and DCS, for explicit vibrational and rotational transitions, were calculated for hydrogen and nitrogen molecules. For higher accuracy, a non-Franck-Condon approach was used to obtain transitions involving vibrational states. The resultant values have shown good agreement with the available experimental data.

Monsoonal precipitation over Peninsular Malaysia in the CMIP6 HighResMIP experiments: the role of model resolution

This study investigates the ability of 20 model simulations which contributed to the CMIP6 HighResMIP to simulate precipitation in different monsoon seasons and extreme precipitation events over Peninsular Malaysia. The model experiments utilize common forcing but are run with different horizontal and vertical resolutions. The impact of resolution on the models’ abilities to simulate precipitation and associated environmental fields is assessed by comparing multi-model ensembles at different resolutions with three observed precipitation datasets and four climate reanalyses. Model simulations with relatively high horizontal and vertical resolution exhibit better performance in simulating the annual cycle of precipitation and extreme precipitation over Peninsular Malaysia and the coastal regions. Improvements associated with the increase in horizontal and vertical resolutions are also found in the statistical relationship between precipitation and monsoon intensity in different seasons. However, the increase in vertical resolution can lead to a reduction of annual mean precipitation compared to that from the models with low vertical resolutions, associated with an overestimation of moisture divergence and underestimation of lower-tropospheric vertical ascent in the different monsoon seasons. This limits any improvement in the simulation of precipitation in the high vertical resolution experiments, particularly for the Southwest monsoon season.

Identification of glycerophospholipids using self-built recognition software based on positive and negative ion high-resolution mass spectrometric fragmentation experiments

Glycerophospholipids (GPs) have a wide variety and complex structure, which makes their identification challenging. Our software affords a novel tool for the automated identification of non-target GPs in biological mixtures. Here, we explored the multi-stage fragmentation processes of GPs in positive and negative ion modes, and then constructed multi-stage fragment ion databases. This database includes 8214 simulated GP molecules from a random combination of fatty acids corresponding to 42,439 self-built predicted multi-stage fragment ions in positive ion mode and 31,487 self-built predicted multi-stage fragment ions in negative ion mode (MS ≤ 3). The automatic GP identification (AGPI) software can screen out GP candidates utilizing the MS1 accurate mass. The isomers of fatty acid chains and the phosphoryl head group can be distinguished using the MS2 and MS3 fragment spectra in positive-ion and negative-ion modes. All of the selected 45 GP standards were putatively identified using AGPI software; however, there were false positives because the software cannot distinguish positional isomers of fatty acids. Therefore, the AGPI software could be applied to identify GPs in samples, such as cancer cells; we successfully identified 41 GPs in cancer cells.

Gas-phase CO2 activation with single electrons, metal atoms, clusters, and molecules

In this review, the history and outlook of gas-phase CO2 activation using single electrons, metal atoms, clusters (mainly metal hydride clusters), and molecules are discussed on both of the experimental and theoretical fronts. Although the development of bulk solid-state materials for the activation and conversion of CO2 into value-added products have enjoyed great success in the past several decades, this review focuses only on gas-phase studies, because isolated, well-defined gas-phase systems are ideally suited for high-resolution experiments using state-of-the-art spectrometric and spectroscopic techniques, and for simulations employing modern quantum theoretical methods. The unmatched high complementarity and comparability of experiment and theory in the case of gas-phase investigations bear an enormous potential in providing insights in the reactions of CO2 activation at the atomic level. In all of these examples, the reduction and bending of the inert neutral CO2 molecule is the critical step determined by the frontier orbitals of reaction participants. Based on the results and outlook summarized in this review, we anticipate that studies of gas-phase CO2 activations will be an avenue rich with opportunities for the rational design of novel catalysts based on the knowledge obtained on the atomic level.

MADNet 2.0: Pixel-Scale Topography Retrieval from Single-View Orbital Imagery of Mars Using Deep Learning

The High-Resolution Imaging Science Experiment (HiRISE) onboard the Mars Reconnaissance Orbiter provides remotely sensed imagery at the highest spatial resolution at 25–50 cm/pixel of the surface of Mars. However, due to the spatial resolution being so high, the total area covered by HiRISE targeted stereo acquisitions is very limited. This results in a lack of the availability of high-resolution digital terrain models (DTMs) which are better than 1 m/pixel. Such high-resolution DTMs have always been considered desirable for the international community of planetary scientists to carry out fine-scale geological analysis of the Martian surface. Recently, new deep learning-based techniques that are able to retrieve DTMs from single optical orbital imagery have been developed and applied to single HiRISE observational data. In this paper, we improve upon a previously developed single-image DTM estimation system called MADNet (1.0). We propose optimisations which we collectively call MADNet 2.0, which is based on a supervised image-to-height estimation network, multi-scale DTM reconstruction, and 3D co-alignment processes. In particular, we employ optimised single-scale inference and multi-scale reconstruction (in MADNet 2.0), instead of multi-scale inference and single-scale reconstruction (in MADNet 1.0), to produce more accurate large-scale topographic retrieval with boosted fine-scale resolution. We demonstrate the improvements of the MADNet 2.0 DTMs produced using HiRISE images, in comparison to the MADNet 1.0 DTMs and the published Planetary Data System (PDS) DTMs over the ExoMars Rosalind Franklin rover’s landing site at Oxia Planum. Qualitative and quantitative assessments suggest the proposed MADNet 2.0 system is capable of producing pixel-scale DTM retrieval at the same spatial resolution (25 cm/pixel) of the input HiRISE images.

In situ high-pressure nuclear magnetic resonance crystallography in one and two dimensions

Recent developments in in situ nuclear magnetic resonance (NMR) spectroscopy under extreme conditions have led to the observation of a wide variety of physical phenomena that are not accessible with standard high-pressure experimental probes. However, inherent di- or quadrupolar line broadening in diamond anvil cell (DAC)-based NMR experiments often limits detailed investigation of local atomic structures, especially if different phases or local environments coexist. Here, we describe our progress in the development of high-resolution NMR experiments in DACs using one- and two-dimensional homonuclear decoupling experiments at pressures up to the megabar regime. Using this technique, spectral resolutions of the order of 1 ppm and below have been achieved, enabling high-pressure structural analysis. Several examples are presented that demonstrate the wide applicability of this method for extreme conditions research.

Interplay between Local Structure and Nuclear Dynamics in Tungstic Acid: A Neutron Scattering Study

We provide an exhaustive characterization of structural properties and nuclear dynamics in tungstic acid (WO3·H2O). To this end, we employ neutron and X-ray diffraction (ND and XRD) combined with inelastic neutron scattering (INS) and neutron Compton scattering (NCS) experiments, and we corroborate the analysis with extensive ab initio modeling. The first step in our analysis is the elucidation of the crystal structure based on the refinement of low-temperature powder ND data, extending the knowledge gained from XRD analysis of a mineral specimen of tungstite. These results are confronted with low-temperature INS experiments and zero-temperature phonon calculations. The analysis reveals an inconsistency in the definition of the structure of confined water with respect to crystallographic data, also showing a concomitant failure of the phonon calculations due to a strongly anharmonic confining potential. Extending the computational route toward ab initio MD (AIMD) simulations allows us to probe different structural configurations and provides an improved description of the vibrational dynamics as compared to high-resolution INS experiments, nevertheless, requiring the use of effective classical temperatures. The analysis of both INS and the NCS data reveals a remarkable similarity to the nuclear dynamics earlier reported for water confined in single-wall carbon nanotubes (SWNT), which has been qualitatively described as a new phase of ice. Our analysis reveals a strong two-dimensional hydrogen-bonding network, similar to the shell model for water in SWNT. The reported NCS data show narrowing of the hydrogen momentum distribution with respect to the reference ab initio calculations, indicating a great deal of conformational freedom due to spatial delocalization of protons in the ground state of the system, a clear signature of the quantum character of the nuclei.

Magic Numbers in Boson 4He Clusters: The Auger Evaporation Mechanism.

The absence of magic numbers in bosonic 4He clusters predicted by all theories since 1984 has been challenged by high-resolution matter-wave diffraction experiments. The observed magic numbers were explained in terms of enhanced growth rates of specific cluster sizes for which an additional excitation level calculated by diffusion Monte Carlo is stabilized. The present theoretical study provides an alternative explanation based on a simple independent particle model of the He clusters. Collisions between cluster atoms in excited states within the cluster lead to selective evaporation via an Auger process. The calculated magic numbers as well as the shape of the number distributions are in quite reasonable agreement with the experiments.

Large-amplitude longitudinal oscillations in solar prominences simulated with different resolutions

Context. Large-amplitude longitudinal oscillations (LALOs) in solar prominences have been widely studied in recent decades. However, their damping and amplification mechanisms are not well understood. Aims. In this study, we investigate the attenuation and amplification of LALOs using high-resolution numerical simulations with progressively increasing spatial resolutions. Methods. We performed time-dependent numerical simulations of LALOs using the 2D magnetic configuration that contains a dipped region. After the prominence mass loading in the magnetic dips, we triggered LALOs by perturbing the prominence mass along the magnetic field. We performed the experiments with four values of spatial resolution. Results. In the simulations with the highest resolution, the period shows good agreement with the pendulum model. The convergence experiment revealed that the damping time saturates at the bottom prominence region with increasing resolution, indicating the existence of a physical reason for the damping of oscillations. At the prominence top, the oscillations are amplified during the first minutes and are then slowly attenuated. The characteristic time suggests more significant amplification in the experiments with the highest spatial resolution. The analysis revealed that the energy exchange between the bottom and top prominence regions is responsible for the attenuation and amplification of LALOs. Conclusions. High-resolution experiments are crucial when studying the periods and the damping mechanism of LALOs. The period agrees with the pendulum model only when using a sufficiently high spatial resolution. The results suggest that numerical diffusion in simulations with insufficient spatial resolution can hide important physical mechanisms, such as amplification of oscillations.

CYTOGENETIC AND CLINICAL DATA OF VARIANT THREE-WAY TRANSLOCATIONS T(8;V;21) IN CHILDHOOD ACUTE MYELOID LEUKEMIA

Core binding factor (CBF) leukemias represent an important prognostic group in acute myeloid leukemia (AML). The t(8;21)(q22;q22)/ RUNX1 - RUNX1T1 is one of the most frequent abnormalities in childhood AML (7–16%) and is related to a good prognosis. However, on rare occasions, an additional chromosome may be involved in this translocation, which may result in a poor clinical outcome for the patient. In this sense, the prognostic value of the RUNX1 - RUNX1T1 fusion has been widely discussed in the literature. Approximately 3–4% of AML cases with t(8;21)/ RUNX1 - RUNX1T1 occur in the context of complex rearrangements, with only a few cases reported in children (0.05–1.1%). Our aim in this work is to demonstrate the clinical and molecular data from four AML pediatric patients with variant three-way translocations t(8;V;21), characterizing in detail the extra chromosomes and fusion products. In our cohort of 146 children diagnosed with AML, we observed 22 with complex karyotypes (>3 abnormalities). To date, we detected the t(8;21) in 5/22 cases, among which 4 patients presented the involvement of a third chromosome in t(8;21), characterizing variant three-way translocations t(8;V;21). To characterize the patient's karyotypes, G-banding, FISH, and high-resolution molecular cytogenetics experiments (PCP, WCP, M-FISH, and MCB) were performed on bone marrow and/or peripheral blood cells under standard protocols. Regarding the mechanism of this type of translocation, Downing et al. (1993) and Tanaka et al. (2012) reported that there are at least two stages for the formation of such complex variants. The region 21(q22) (harboring the RUNX1 gene) translocates to the long arm of chromosome 8, while region 8q22 (harboring the RUNX1T1 gene) translocates to a third chromosome. Interestingly, in our 4 cases, t(8;V;21) demonstrated the same biological behavior in the rearrangement as the other cases reported in the literature. Although, unlike the cases previously reported in the literature, the karyotypes characterized in our study were cryptic, reaffirming the importance of an accurate diagnosis of RUNX1 - RUNX1T1 fusion products. With our approach by molecular cytogenetic techniques, we were able to precisely define the breakpoints of the three-way translocations, which will be of importance for future studies, investigating putative genes with impact on the genesis of pediatric CBF leukemias.

Compressible EULAG Dynamical Core in COSMO: Convective-Scale Alpine Weather Forecasts

AbstractThis paper presents the semi-implicit compressible EULAG as a new dynamical core for convective-scale numerical weather prediction. The core is implemented within the infrastructure of the operational model of the Consortium for Small-Scale Modeling (COSMO), forming the NWP COSMO-EULAG model (CE). This regional high-resolution implementation of the dynamical core complements its global implementation in the Finite-Volume Module of ECMWF’s Integrated Forecasting System. The paper documents the first operational-like application of the dynamical core for realistic weather forecasts. After discussing the formulation of the core and its coupling with the host model, the paper considers several high-resolution prognostic experiments over complex Alpine orography. Standard verification experiments examine the sensitivity of the CE forecast to the choice of the advection routine and assess the forecast skills against those of the default COSMO Runge–Kutta dynamical core at 2.2-km grid size showing a general improvement. The skills are also compared using satellite observations for a weak-flow convective Alpine weather case study, showing favorable results. Additional validation of the new CE framework for partly convection-resolving forecasts using 1.1-, 0.55-, 0.22-, and 0.1-km grids, designed to challenge its numerics and test the dynamics–physics coupling, demonstrates its high robustness in simulating multiphase flows over complex mountain terrain, with slopes reaching 85°, and the flow’s realistic representation.

Evaluating the mitigation strategies of COVID-19 by the application of the CO2 emission data through high-resolution agent-based computational experiments.

The negative consequences, such as healthy and environmental issues, brought by rapid urbanization and interactive human activities result in increasing social uncertainties, unreliable predictions, and poor management decisions. For instance, the Coronavirus Disease (COVID-19) occurred in 2019 has been plaguing many countries. Aiming at controlling the spread of COVID-19, countries around the world have adopted various mitigation and suppression strategies. However, how to comprehensively eva luate different mitigation strategies remains unexplored. To this end, based on the Artificial societies, Computational experiments, Parallel execution (ACP) approach, we proposed a system model, which clarifies the process to collect the necessary data and conduct large-scale computational experiments to evaluate the effectiveness of different mitigation strategies. Specifically, we established an artificial society of Wuhan city through geo-environment modeling, population modeling, contact behavior modeling, disease spread modeling and mitigation strategy modeling. Moreover, we established an evaluation model in terms of the control effects and economic costs of the mitigation strategy. With respect to the control effects, it is directly reflected by indicators such as the cumulative number of diseases and deaths, while the relationship between mitigation strategies and economic costs is built based on the emission. Finally, large-scale simulation experiments are conducted to evaluate the mitigation strategies of six countries. The results reveal that the more strict mitigation strategies achieve better control effects and less economic costs.

Nickel(II)-Catalyzed [3 + 2] Cycloaddition of Nitrones and Allenoates to Access N-Vinylindoles and N-Vinylpyrroles.

A variety of N-vinylindoles and N-vinylpyrroles were prepared in moderate to good yields through the nickel(II)-catalyzed [3 + 2] cycloaddition of α,β-unsaturated nitrones with allenoates under mild reaction conditions. A rational mechanism for the formation of N-vinylindoles was proposed based on the 18O-labeled experiments and key intermediates detected by high-resolution mass spectrometry trace experiments. The present method highlights a nickel(II)-controlled cyclization, atom-economical reaction, broad substrate scope, good functional group tolerance, and high Z-stereoselectivity for the enamine bond.

Evaluating Stereo Digital Terrain Model Quality at Mars Rover Landing Sites with HRSC, CTX, and HiRISE Images

We have used high-resolution digital terrain models (DTMs) of two rover landing sites based on mosaicked images from the High-Resolution Imaging Science Experiment (HiRISE) camera as a reference to evaluate DTMs based on High-Resolution Stereo Camera (HRSC) and Context Camera (CTX) images. The Next-Generation Automatic Terrain Extraction (NGATE) matcher in the SOCET SET and GXP® commercial photogrammetric systems produces DTMs with good (small) horizontal resolution but large vertical error. Somewhat surprisingly, results for NGATE are terrain dependent, with poorer resolution and smaller errors on smoother surfaces. Multiple approaches to smoothing the NGATE DTMs give similar tradeoffs between resolution and error; a 5 × 5 lowpass filter is near optimal in terms of both combined resolution-error performance and local slope estimation. Smoothing with an area-based matcher, the standard processing for U.S. Geological Survey planetary DTMs, yields similar errors to the 5 × 5 filter at slightly worse resolution. DTMs from the HRSC team processing pipeline fall within this same trade space but are less sensitive to terrain roughness. DTMs produced with the Ames Stereo Pipeline also fall in this space at resolutions intermediate between NGATE and the team pipeline. Considered individually, resolution and error each varied by approximately a factor of 2. Matching errors were 0.2–0.5 pixels but most results fell in the 0.2–0.3 pixel range that has been stated as a rule of thumb in multiple prior studies. Horizontal resolutions of 10–20 image pixels were found, consistently greater than the 3–5 pixel spacing generally used for stereo DTM production. Resolution and precision were inversely correlated; their product varied by ≤20% (4–5 pixels squared). Refinement of the stereo DTM by photoclinometry can yield quantitative improvement in resolution (more than a factor of 2), provided that albedo variations over distances smaller than the stereo DTM resolution are not too severe. We offer specific guidance for both producers and users of planetary stereo DTMs, based on our results.

Preparation of melamine-functionalized porous organic polymer and its adsorption properties for methyl orange

首先以对三联苯(TP)和对苯二甲酰氯(TC)为单体合成了酮基聚合物前体(TP-TC),而后基于席夫碱反应将三聚氰胺(MA)与之交联得到胺功能化的多孔有机聚合物TP-TC-MA。通过扫描电镜(SEM)、透射电镜(TEM)、傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)、氮气吸附-脱附(BET)以及零电荷点(pHpzc)的测定等手段对合成的多孔有机聚合物进行表征。以染料废水中典型的阴离子染料甲基橙为研究对象,研究了TP-TC-MA对其吸附行为,并探讨了吸附机制。利用紫外-可见分光光度计(UV-Vis)得出目标污染物的紫外吸收光谱标准曲线,标准曲线拟合相关系数(R2)为0.999。结果表明,TP-TC-MA由于具有高比表面积(708.5 m2/g)和总孔体积(0.556 cm3/g)以及丰富的含氮基团,对阴离子染料甲基橙表现出优异的吸附性能。TP-TC-MA对水中甲基橙的吸附动力学符合准二级动力学方程,吸附平衡数据可以采用Langmuir等温吸附模型描述。经由Langmuir等温吸附模型计算得到的理论最大吸附容量为156.3 mg/g。选择性实验结果表明,TP-TC-MA对阴离子染料甲基橙具有更强的吸附作用,吸附作用机理可归结为静电相互作用、氢键和π-π相互作用等。在重复使用5次之后,TP-TC-MA对甲基橙仍保持90%以上的去除率,表明材料具有良好的稳定性和重复利用性,在染料废水处理中具有很好的应用前景。

On the formation mechanism of cirrus banding: radiosonde observations, numerical simulations, and stability analyses

AbstractThe structures and formation mechanisms of cirrus banding are investigated by analyzing radiosonde observations, conducting high-resolution numerical experiments, and performing linear stability analyses. In all 29 cases of cirrus bands that were analyzed, radiosonde observational data indicate that statically unstable layers exist. The detected banding clouds were aligned nearly parallel to the vertical shear vector in the unstable layer. In high-resolution numerical experiments using the cloud-resolving model SCALE-RM, cirrus bands forming in the outflow layer of a tropical cyclone are explicitly simulated. The existence of statically unstable layers and band-parallel background vertical wind shear are commonly identified in the simulations. Sensitivity experiments and heat budget analyses demonstrated that the unstable stratification within the cirrus clouds was maintained by the cloud-radiation interactions. To reveal the behavior of fluid instabilities in the cirrus bands, linear stability analyses in a basic state constructed from the radiosonde observations were performed. The fastest-growing disturbance is highly similar to that of the previously known thermal-shear instability in a uniform and isolated unstable layer and the results obtained by radiosonde observations and numerical simulations. All of the results consistently indicate that thermal-shear instability is responsible for the formation of cirrus banding. Our results not only follow previous modeling studies but also provide observational support, quantification of the destabilization by the cloud-radiation interactions, as well as a theoretical basis of the thermal-shear instability in a complex environment near cirrus bands.