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91.
《Annals of Pure and Applied Logic》2022,173(8):103135
We further develop a forcing notion known as Coding with Perfect Trees and show that this poset preserves, in a strong sense, definable P-points, definable tight MAD families and definable selective independent families. As a result, we obtain a model in which , each of , , has a witness and there is a well-order of the reals. Note that both the complexity of the witnesses of the above combinatorial cardinal characteristics, as well as the complexity of the well-order are optimal. In addition, we show that the existence of a well-order of the reals is consistent with and each of the following: , , , where the smaller cardinal characteristics have co-analytic witnesses.Our methods allow the preservation of only sufficiently definable witnesses, which significantly differs from other preservation results of this type. 相似文献
92.
Dong Gun Oh Prof. Hristiyan A. Aleksandrov Haneul Kim Dr. Iskra Z. Koleva Dr. Konstantin Khivantsev Prof. Georgi N. Vayssilov Prof. Ja Hun Kwak 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(49):e202200684
Pd-based catalysts are the most widely used for CO oxidation because of their outstanding catalytic activity and thermal stability. However, fundamental understanding of the detailed catalytic processes occurring on Pd-based catalysts under realistic conditions is still lacking. In this study, we investigated CO oxidation on metallic Pd clusters supported on Al2O3 and SiO2. High-angle annular dark-field scanning transmission electron microscopy revealed the formation of similar-sized Pd clusters on Al2O3 and SiO2. In contrast, CO chemisorption analysis indicated a gradual change in the dispersion of Pd (from 0.79 to 0.2) on Pd/Al2O3 and a marginal change in the dispersion (from 0.4 to 0.24) on Pd/SiO2 as the Pd loading increased from 0.27 to 5.5 wt %; these changes were attributed to differences in the metal-support interactions. Diffuse reflectance infrared Fourier-transform spectroscopy revealed that fewer a-top CO species were present in Pd supported on Al2O3 than those in Pd supported on SiO2, which is related to the morphological differences in the metallic Pd clusters on these two supports. Despite the different dispersion profiles and surface characteristics of Pd, O2 titration demonstrated that linearly bound CO (with an infrared signal at 2090 cm−1) reacted first with oxygen in the case of CO-saturated Pd on Al2O3 and SiO2, which suggests that a-top CO on the terrace site plays an important role in CO oxidation. The experimental observations were corroborated by periodic density functional calculations, which confirmed that CO oxidation on the (111) terrace sites is most plausible, both kinetically and thermodynamically, compared to that on the edge or corner sites. This study will deepen the fundamental understanding of the effect of Pd clusters on CO oxidation under reaction conditions. 相似文献
93.
Gang Li Libo Liao Xinchou Lou Peixun Shen Weimin Song Shudong Wang Zhaoling Zhang 《中国物理C(英文版)》2022,46(11):113001-113001-8
Various Higgs factories are proposed to study the Higgs boson precisely and systematically in a model- independent way. In this study, the Particle Flow Network and ParticleNet techniques are used to classify the Higgs decays into multicategories, and the ultimate goal is to realize an "end-to-end" analysis. A Monte Carlo simulation study is performed to demonstrate the feasibility, and the performance looks rather promising. This result could be the basis of a "one-stop" analysis to measure all the branching fractions of the Higgs decays simultaneously. 相似文献
94.
Yuanyuan Cui Yaoyang Meng Yun Hu Yuqi Chen Yixian Yang Min Fang Cun Li Weiju Zhu 《中国化学会会志》2023,70(1):68-75
A novel fluorescent probe, LCH , based on dicyanisophorone and carbazole, was prepared for the visual detection of Cu2+. The probe LCH could recognize Cu2+ by fluorescence quenching in EtOH/H2O (1/4, v/v) solution, which could be easily identified under the 365 nm UV lamp, and the detection limit was as low as 0.785 μM. The recognition mechanism of probe LCH with Cu2+ was determined by combining 1H NMR titration, MS, and theoretical calculations. Practical application experiments showed that probe LCH could be used to detect Cu2+ in the test strip experiments. Cell imaging experiments showed that the probe LCH owned good cell permeability and could be applied to the imaging of Cu2+ in HepG2 cells. In addition, fluorescence colocalization experiments showed that LCH could target lipid droplets. These results indicate that the probe LCH will have a good application prospect in environmental detection and clinical medicine. 相似文献
95.
Fabien Pascale Klaus Doll Francesco Silvio Gentile Roberto Dovesi 《Journal of computational chemistry》2023,44(2):65-75
The ferromagnetic and antiferromagnetic wave functions of the KMnF3 perovskite have been evaluated quantum-mechanically by using an all electron approach and, for comparison, pseudopotentials on the transition metal and the fluorine ions. It is shown that the different number of α and β electrons in the d shell of Mn perturbs the inner shells, with shifts between the α and β eigenvalues that can be as large as 6 eV for the 3s level, and is far from negligible also for the 2s and 2p states. The valence electrons of F are polarized by the majority spin electrons of Mn, and in turn, spin polarize their 1s electrons. When a pseudopotential is used, such a spin polarization of the core functions of Mn and F can obviously not take place. The importance of such a spin polarization can be appreciated by comparing (i) the spin density at the Mn and F nuclear position, and then the Fermi contact constant, a crucial quantity for the hyperfine coupling, and (ii) the ferromagnetic–antiferromagnetic energy difference, when obtained with an all electron or a pseudopotential scheme, and exploring how the latter varies with pressure. This difference is as large as 50% of the all electron datum, and is mainly due to the rigid treatment of the F ion core. The effect of five different functionals on the core spin polarization is documented. 相似文献
96.
利用ALD制备了TiO2限域的Pd催化剂, 研究了限域空间内Pd纳米颗粒与TiO2的界面作用对1,4-丁炔二醇(BYD)加氢性能的影响. 相比于管外负载型催化剂, 限域催化剂在催化1,4-丁炔二醇选择性加氢反应中体现出非常高的催化活性和1,4-丁烯二醇的选择性. HR-TEM、 EDX-Mapping、 XRD、 XPS和H2-TPR表征说明, 限域体系中Pd-TiO2的界面相互作用强于传统TiO2表面负载型Pd催化剂, 这种强界面作用不仅能够提高BYD的加氢活性, 也可抑制半加氢产物1,4-丁烯二醇的异构化和深度加氢, 提高1,4-丁烯二醇的选择性, 而且限域结构也可阻止管内壁Pd纳米颗粒的脱落, 提高催化剂的稳定性. 相似文献
97.
1902年,瑞士化学家维尔纳对氯化铵结构的解释为氢键概念的形成奠定了基础。1920年,美国化学家拉提麦尔和罗德布什首先认识了水中的氢键:2个八隅体所持的氢核构成的“弱键(weak bond)”。1928年,美国化学家鲍林在解释[FHF]-的结构时首次使用“氢键(hydrogen bond)”一词,但并未对氢键的概念进行明确定义。1939年,鲍林在《化学键的本质》中明确提出了氢键的概念,并解释了氢键的性质,自此,氢键的概念正式形成。近年来,科学家经过深入研究发现了氢键的新类型:π型氢键、双氢键、金属氢键和单电子氢键。随着科学思想和科学技术的发展,关于氢键的认识也会越来越深入。 相似文献
98.
Simultaneous application of multiple sinusoidal waveforms perturbations superimposed onto DC staircase step significantly enriches current response. The measured current is characterized by a matrix of data rather than a conventional voltammetric output in a form of a vector. This increase of the dimensionality of the current response and therefore the wealth of analytical information is achieved without compromising the time of analysis. The natural approach for compression of such data and extraction of relevant information is by utilizing multi-way chemometric decomposition techniques. An electroplating solution presents a very challenging analyte for electroanalysis as its constituents interact synergistically with each other during both the plating process and its simulation during electroanalysis. For some components the mechanism is not entirely understood. Therefore, the only way to benefit from the analytical data is by employing soft modeling. The electrode processes involving additives rely heavily on adsorption and, indirectly, on electron transfer kinetics for which AC voltammetry is an analytical technique capable of delivering informative signals. This paper presents a rigorous universal method for calculating and validating an exemplary multi-way calibration of a leveler component in a copper electroplating bath used in the semiconductor industry. The method presented employs comparatively Parallel Factor Analysis coupled with Inverse Least Squares Regression and multi-linear Partial Least Squares. The calibration training set consists of multi-frequency AC voltammetric data subjected to pretreatments aiming to select informative independent variables and exclude outliers. 相似文献
99.
Xiaoyu Liu Haolin Lu Prof. Shengli Zhu Prof. Zhenduo Cui Prof. Zhaoyang Li Prof. Shuilin Wu Prof. Wence Xu Prof. Yanqin Liang Prof. Guankui Long Prof. Hui Jiang 《Angewandte Chemie (International ed. in English)》2023,62(13):e202300800
It is challenging to design one non-noble material with balanced bifunctional performance for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for commercial sustainability at a low cost since the different electrocatalytic mechanisms are not easily matchable for each other. Herein, a self-standing hybrid system Ni18Fe12Al70, consisting of Ni2Al3 and Ni3Fe phases, was constructed by laser-assisted aluminum (Al) incorporation towards full water splitting. It was found that the incorporation of Al could effectively tune the morphologies, compositions and phases. The results indicate that Ni18Fe12Al70 delivers an extremely low overpotential to trigger both HER (η100=188 mV) and OER (η100=345 mV) processes and maintains a stable overpotential for 100 h, comparable to state-of-the-art electrocatalysts. The synergistic effect of Ni2Al3 and Ni3Fe alloys on the HER process is confirmed based on theoretical calculation. 相似文献
100.
《印度化学会志》2023,100(1):100860
This study investigates the influence of synthesis processes such as sonication, sol-gel, and microwave on the production of highly crystalline Lanthanum oxide nanoparticles (La2O3) employing Lanthanum nitrate and Ammonium hydroxide (NH4OH) as precursors. X-ray diffraction (XRD), particle size analysis (DLS), Field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible absorption spectroscopy (UV–Vis), and electrochemical impedance spectroscopy (EIS) were used to examine the most effective processing method and its effects on the nanoparticle characteristics, such as structure, morphology, and optical and electrical behavior. Sonication produces La2O3 NPs with a smaller crystalline size, an agglomerated nanorod structure, a higher bandgap, and better electrical responsiveness than sol-gel and microwave techniques. Structural and optical characterization tests discovered this. The photocatalytic degradation activity of cationic Safranin and anionic Congo red dye exhibits degradation efficiency of around 90.13% and 89.66%, respectively. 相似文献