Examples of rank 3 product action transitive decompositions

A transitive decomposition is a pair where Γ is a graph and is a partition of the arc set of Γ such that there is a subgroup of automorphisms of Γ which leaves invariant and transitively permutes the parts in . In an earlier paper we gave a characterisation of G-transitive decompositions where Γ is the graph product K _m × K _m and G is a rank 3 group of product action type. This characterisation showed that every such decomposition arose from a 2-transitive decomposition of K _m via one of two general constructions. Here we use results of Sibley to give an explicit classification of those which arise from 2-transitive edge-decompositions of K _m .      

Promoting CO2 Electroreduction to Multi-Carbon Products by Hydrophobicity-Induced Electro-Kinetic Retardation

Advancing the performance of the Cu-catalyzed electrochemical CO₂ reduction reaction (CO₂RR) is crucial for its practical applications. Still, the wettable pristine Cu surface often suffers from low exposure to CO₂, reducing the Faradaic efficiencies (FEs) and current densities for multi-carbon (C₂₊) products. Recent studies have proposed that increasing surface availability for CO₂ by cation-exchange ionomers can enhance the C₂₊ product formation rates. However, due to the rapid formation and consumption of *CO, such promotion in reaction kinetics can shorten the residence of *CO whose adsorption determines C₂₊ selectivity, and thus the resulting C₂₊ FEs remain low. Herein, we discover that the electro-kinetic retardation caused by the strong hydrophobicity of quaternary ammonium group-functionalized polynorbornene ionomers can greatly prolong the *CO residence on Cu. This unconventional electro-kinetic effect is demonstrated by the increased Tafel slopes and the decreased sensitivity of *CO coverage change to potentials. As a result, the strongly hydrophobic Cu electrodes exhibit C₂₊ Faradaic efficiencies of ≈90 % at a partial current density of 223 mA cm⁻², more than twice of bare or hydrophilic Cu surfaces.     

Use of a MDI-functionalized reactive polymer for the manufacture of modified bitumen with enhanced properties for roofing applications

In this study, the suitability of a reactive polymer, synthesized by reaction of 4,4′-diphenylmethane diisocyanate (MDI) with a low molecular weight polyethylene-glycol (PEG), as a modifying agent for the manufacture of bitumen-based waterproof membranes, was evaluated. With that purpose, rheological and thermal analysis tests, and microstructural observations by AFM were carried out on different samples of modified bitumen having a MDI–PEG content ranging from 0 to 10 wt.%, cured at room temperature for a period of time within 0–30 days. The results obtained demonstrate that the addition of the reactive polymer proposed in this work to bitumen is very suitable at high in-service temperatures, because a noticeable increase in the values of viscosity, at 60 °C, of the resulting modified bitumen samples is observed on a time-scale of days. AFM observations, carried out at 50 °C, evidenced that the reactive polymer MDI–PEG leads to a new microstructure, displaying a higher level of stiffness. Therefore, this polymer should be seriously taken into consideration as a modifier of bituminous coatings for the waterproofing industry.     

Psychoacoustics of in-car switch buttons: From feelings to engineering parameters

The car interior is becoming quieter and other sounds are now exposed to user perception, such as the sound produced by interface buttons when actuated. So, the functional role of the button sound on interface operation and its aesthetic and emotional role on the user experience are now more important than before. However, little research and design effort has been paid to understand how to design buttons that produce a pleasant sound. Moreover, the button’s sound requirements received by interface manufacturers are ill-defined, insufficient or even inexistent, and consequently their conversion into specifications for manufacturing is problematic and leads to long and costly development processes. The purpose of this paper is to contribute to identify relevant acoustic parameters that explain the users sound preferences. Data on preference subjective judgments were collected and buttons acoustic signals were measured allowing the development of preference models based on partial least squares regression and neural networks methods. The former was successful in selecting the relevant parameters to describe the preference ratings of the buttons sound. The later, dealing with the non-linear nature of acoustic perception, was able to predict preferences based on the relevant parameters.     

我国丁腈橡胶产业发展现状及未来发展趋势

概述了全球丁腈橡胶(NBR)的产能等状况,分析了我国NBR的产能、产量及消费现状,介绍了我国主要NBR生产厂家的产品结构和价格变化等情况。从环保型NBR开发、三元共聚NBR、氢化丁腈橡胶(HNBR)产品开发、乳液聚合动力学基础研究、NBR在线监测技术发展及国内NBR在关键技术进步、聚合工艺改进和新产品开发等几个方面介绍了国内外NBR生产技术的最新进展,并展望了我国未来NBR的市场及技术发展趋势。紧密联系市场,优化聚合反应配方,改进生产工艺,提高过程控制水平,研发高性能NBR的新牌号,绿色环保化生产及提高产品服务质量是增强NBR产品市场竞争力的重要举措。     

CDn体系DEPT谱线的理论研究

本文根据算符函数的幂级数展开,给出了描述高自旋弱耦合体系的积算符理论,并用来描述I_n S((1)/2)体系(其中I=1/2,1,…)的DEPT实验.给出I(1)_n S((1)/2)体系(例如CD_n)DEPT谱线的增益系数的普遍公式,并提出了用作图法得出谱线结构的方法.     

脉冲梯度场增强的DQF-COSY实验t1噪声研究

脉冲相位的不稳定性是导致二维谱中的t₁噪声的原因之一.本文从理论上和实验上对脉冲相位不稳定性所引起的t₁噪声进行了研究.从角动量算符I_x,I_y和I_z推导中发现,由于磁化矢量在P型和N型DQF-COSY实验的脉冲梯度场中进动方向的内在差异,一部分脉冲相位误差在P型DQF-COSY实验会被重聚掉,在N型DQF-COSY实验中却会被加重.因此P型DQF-COSY实验的t₁噪声比N型小.理论推导还得到t₁噪声在P型和N型中的理论比值为√3:√11.以上理论结果得到我们实验结果的支持.     

N2O同位素的紫外光解：同位素分馏和产物的转动量子态分布

采用时间依赖的量子波包法研究¹⁴N¹⁴N¹⁶O、¹⁴N¹⁵N¹⁶O、¹⁵N¹⁴N¹⁶O、¹⁵N¹⁵N¹⁶O、¹⁴N¹⁴N¹⁷O和¹⁴N^{14相似文献}   

微波消解石墨炉原子吸收光谱法测定水产品中镉

采用微波消解样品,石墨炉原子吸收光谱法测定水产品中镉。在最佳试验条件下,镉的线性范围为0—2μg·L-1,检出限为1.3pg。相对标准偏差为1.9%—3.1%,本方法简便,快速、准确。