Electron-phonon interactions in MoS2ﾠprobed with ultrafast two-dimensional visible/far-infrared spectroscopy

An ultrafast two-dimensional visible/far-IR spectroscopy based on the IR/THz air biased coherent detection method and scanning the excitation frequencies is developed. The method allows the responses in the far-IR region caused by various electronic excitations in molecular or material systems to be observed in real time. Using the technique, the relaxation dynamics of the photo-excited carriers and electron/phonon coupling in bulk MoS2 are investigated. It is found that the photo-generation of excited carriers occurs within two hundred fs and the relaxation of the carriers is tens of ps. The electron-phonon coupling between the excitations of electrons and the phonon mode E1u of MoS2 is also directly observed. The electron excitation shifts the frequency of the phonon mode 9 cm−1 higher, resulting in an absorption peak at 391 cm−1 and a bleaching peak at 382 cm−1. The frequency shift diminishes with the relaxation of the carriers

Multilevel Matrix Factor Model

Large-scale matrix data has been widely discovered and continuously studied in various fields recently. Considering the multi-level factor structure and utilizing the matrix structure, we propose a multilevel matrix factor model with both global and local factors. The global factors can affect all matrix times series, whereas the local factors are only allow to affect within each specific matrix time series. The estimation procedures can consistently estimate the factor loadings and determine the number of factors. We establish the asymptotic properties of the estimators. The simulation is presented to illustrate the performance of the proposed estimation method. We utilize the model to analyze eight indicators across 200 stocks from ten distinct industries, demonstrating the empirical utility of our proposed approach.Comment: 47 pages, 22 figure

Water-Mediated Ion Pairing: Occurrence and Relevance

We present an overview of the studies of ion pairing in aqueous media of the past decade. In these studies, interactions between ions, and between ions and water, are investigated with relatively novel approaches, including dielectric relaxation spectroscopy, far-infrared (terahertz) absorption spectroscopy, femtosecond mid-infrared spectroscopy, and X-ray spectroscopy and scattering, as well as molecular dynamics simulation methods. With these methods, it is found that ion pairing is not a rare phenomenon only occurring for very particular, strongly interacting cations and anions. Instead, for many salt solutions and their interfaces, the measured and calculated structure and dynamics reveal the presence of a distinct concentration of contact ion pairs (CIPs), solvent shared ion pairs (SIPs), and solvent-separated ion pairs (2SIPs). We discuss the importance of specific ion-pairing interactions between cations like Li+ and Na+ and anionic carboxylate and phosphate groups for the structure and functioning of large (bio)molecular systems

Similar operation template attack on RSA-CRT as a case study

A template attack, the most powerful side-channel attack methods, usually first builds the leakage profiles from a controlled profiling device, and then uses these profiles to recover the secret of the target device. It is based on the fact that the profiling device shares similar leakage characteristics with the target device. In this study, we focus on the similar operations in a single device and propose a new variant of the template attack, called the similar operation template attack (SOTA). SOTA builds the models on public variables (e.g., input/output) and recovers the values of the secret variables that leak similar to the public variables. SOTA’s advantage is that it can avoid the requirement of an additional profiling device. In this study, the proposed SOTA method is applied to a straightforward RSA-CRT implementation. Because the leakage is (almost) the same in similar operations, we reduce the security of RSA-CRT to a hidden multiplier problem (HMP) over GF(q), which can be solved byte-wise using our proposed heuristic algorithm. The effectiveness of our proposed method is verified as an entire prime recovery procedure in a practical leakage scenario

Oxalate as a potent promoter of kidney stone formation

Kidney stones are among the most prevalent urological diseases, with a high incidence and recurrence rate. Treating kidney stones has been greatly improved by the development of various minimally invasive techniques. Currently, stone treatment is relatively mature. However, most current treatment methods are limited to stones and cannot effectively reduce their incidence and recurrence. Therefore, preventing disease occurrence, development, and recurrence after treatment, has become an urgent issue. The etiology and pathogenesis of stone formation are key factors in resolving this issue. More than 80% of kidney stones are calcium oxalate stones. Several studies have studied the formation mechanism of stones from the metabolism of urinary calcium, but there are few studies on oxalate, which plays an equally important role in stone formation. Oxalate and calcium play equally important roles in calcium oxalate stones, whereas the metabolism and excretion disorders of oxalate play a crucial role in their occurrence. Therefore, starting from the relationship between renal calculi and oxalate metabolism, this work reviews the occurrence of renal calculi, oxalate absorption, metabolism, and excretion mechanisms, focusing on the key role of SLC26A6 in oxalate excretion and the regulatory mechanism of SLC26A6 in oxalate transport. This review provides some new clues for the mechanism of kidney stones from the perspective of oxalate to improve the understanding of the role of oxalate in the formation of kidney stones and to provide suggestions for reducing the incidence and recurrence rate of kidney stones

Synthesis, characterization and catalytic methanation performance of modified kaolin-supported Ni-based catalysts

Kaolin as a raw material for mesoporous support was firstly modified by calcination, add treatment, and then was used to prepare nickel catalysts. The amount of alumina which was activated in kaolin during thermal treatment and then leached out in the acid was different. XRD pattern of the kaolin calcined at 600 degrees C or 900 degrees C exhibited only the diffraction peaks for amorphous silica and quartz while that calcined at 1100 degrees C showed obvious peaks for gamma-Al2O3. Therefore, the nickel-based catalysts exhibited different physic-chemical properties. Atmospheric syngas methanation over the catalysts clarified an activity order of CA-1100 > CA-900 > CA-1400 > CA600 > KA approximate to 0 at temperatures of 350-650 degrees C and a space velocity of 120 L.g(-1). h(-1). Metallic nickel with small diameter which has medium interaction with the modified kaolin and is well dispersed on the support would have reasonably good activity and carbon-resistance for syngas methanation. (C) 2019 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved

synthesischaracterizationandcatalyticmethanationperformanceofmodifiedkaolinsupportednibasedcatalysts

Kaolin as a raw material for mesoporous support was firstly modified by calcination, acid treatment, and then was used to prepare nickel catalysts. The amount of alumina which was activated in kaolin during thermal treatment and then leached out in the acid was different. XRD pattern of the kaolin calcined at 600?°C or 900?°C exhibited only the diffraction peaks for amorphous silica and quartz while that calcined at 1100?°C showed obvious peaks for γ-Al 2 O 3 . Therefore, the nickel-based catalysts exhibited different physic-chemical properties. Atmospheric syngas methanation over the catalysts clarified an activity order of CA-1100?>?CA-900?>?CA-1400?>?CA-600?>?KA?≈?0 at temperatures of 350–650?°C and a space velocity of 120?L·g ?1 ·h ?1 . Metallic nickel with small diameter which has medium interaction with the modified kaolin and is well dispersed on the support would have reasonably good activity and carbon-resistance for syngas methanation

synthesischaracterizationandcatalyticmethanationperformanceofmodifiedkaolinsupportednibasedcatalysts

Kaolin as a raw material for mesoporous support was firstly modified by calcination, acid treatment, and then was used to prepare nickel catalysts. The amount of alumina which was activated in kaolin during thermal treatment and then leached out in the acid was different. XRD pattern of the kaolin calcined at 600?°C or 900?°C exhibited only the diffraction peaks for amorphous silica and quartz while that calcined at 1100?°C showed obvious peaks for γ-Al 2 O 3 . Therefore, the nickel-based catalysts exhibited different physic-chemical properties. Atmospheric syngas methanation over the catalysts clarified an activity order of CA-1100?>?CA-900?>?CA-1400?>?CA-600?>?KA?≈?0 at temperatures of 350–650?°C and a space velocity of 120?L·g ?1 ·h ?1 . Metallic nickel with small diameter which has medium interaction with the modified kaolin and is well dispersed on the support would have reasonably good activity and carbon-resistance for syngas methanation