Investigation of the iodine species on platinum catalyst used as hydrogen oxidation

Hydrogen can be oxidized by recombination with atmospheric oxygen over a catalyst, such as Pt/Al₂O₃, at a temperature much lower than that required for thermal oxidation generating heat and water vapor. However, there is potential for the passive autocatalytic recombiner to generate volatile forms of iodine, namely molecular iodine, by catalytic dissociation of various iodine compounds too. The dissociated atomic iodine on the surfaces of the Pt/Al₂O₃ catalyst is mainly measured at ambient temperature as I 3d peaks in X-ray photoelectron spectroscopy. It seems that dissociation of iodine compounds on the catalyst surfaces and then production of gaseous I₂ by recombination of the dissociated iodine occur prior to the oxidation or reduction of iodine compounds under air or H₂. Atomic iodine is predominant on the surfaces of the catalyst in H₂ and air conditions, and it is stable even with exposure to H₂O. Adsorbed iodine prevents the adsorption of H₂ or O₂ for recombination to H₂O, but it can be desorbed completely at a high temperature.     

Gas production from different classes of methane hydrate deposits by the depressurization method

There are four primary classes of natural gas hydrate deposits in natural world. The differences between them are in the distribution of the methane hydrate, free gas, and free water layers. A reactor which the height was 120 mm and the inner diameter was 103 mm was used in hydrate formation and dissociation, and 17 thermocouples measured the distribution of temperature during the mining process. Different experimental means were applied to simulate three classes of methane hydrate deposits, in which water and glass beads filled in different orders. The hydrate samples were dissociated by depressurization, and the results showed no need to test a backpressure greater than 94% of the equilibrium pressure of methane hydrate. Class 1 sample's methane hydrate decomposition rate was slower than that of class 3 sample at the beginning of depressurization when backpressure was 2.3 and 2.6 MPa, but then, the opposite happened. The average dissociation rate decreased nearly linearly with the increase in backpressure for the class 1 samples.     

Testimonial theatre-making: Establishing or dissociating the self.

A group of professional and preprofessional actors (n = 54) from South Africa, (n = 17), the United States (n = 9), and Canada (n = 25) were compared with a healthy and active nonclinical American control group (n = 57) for type of and total traumatic events (TEQ), vividness and extensiveness of fantasy proneness (ICMI), and type and frequency of dissociation (DES-II). All actors had received intensive training in Stanislavski-based acting and participated in theater-making projects that incorporated the creation and performance of testimonial theater. Based on this acting background, we hypothesized that fewer actors would endorse pathological dissociation. This hypothesis was contradicted. Our second hypothesis was found to be correct, that actors endorsed higher fantasy proneness. The last hypothesis was found to be partially correct; fantasy significantly explained some of the variance for dissociation for both the actor and the control groups. There were no significant differences for type and total past traumatic events between the actor and the control groups. Independent sample T tests, multivariate analysis of covariance (with age as a covariate), stepwise linear regression and logistic regression all supported the relationship between fantasy-dissociation in this study. While not minimizing the effect of past trauma, this study revealed that fantasy is significantly associated with the disorienting effects of dissociation. Rather than establishing an integrated self, for some actors, their sense of self remained dissociated. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

废旧线路板环保解离回收处理技术

本技术采用先进的高速祸流粉碎与微分解离新工艺,全封闭处理,不致二次污染,金属回收率达98%.采用机械破碎法对线路板进行破碎,不但节能,而且金属分离率高;再据二者密度差用分选法回收废旧线路板中的铜,将剩余的非金属材料通过特定的工艺制成高分子材料产品.处理能耗低,生产过程无二次污染,达到节能减排和资源回收的双重目的.     

中低品位铝土矿新型正浮选捕收剂的开发研究

针对中低品位铝土矿浮选脱硅过程中存在的一系列问题,以铝土矿工艺矿物学为基础,实现目标矿物的单体解离。根据矿物表面,物理化学性质差异,结合浮选药剂分子设计理论,对铝土矿浮选捕收剂的极性基、非极性基进行重新设计,使药剂基团易于与矿物结合后形成环状螯合物,增强药剂捕收性能,强化药剂选择性能,开发出用量较小、选择性强、泡沫量少的铝土矿新型正浮选捕收剂。     

Establishment and evaluation of strength criterion for clayey silt hydrate-bearing sediments

Appropriate strength criterion is the prerequisite for wellbore stability analysis. In this paper, the Modified Mohr-Coulomb criterion that considering the effects of hydrate is established based on the experimental results of the artificial clayey silt samples with hydrate. Meanwhile, the new criterion was evaluated by comparing the differences in the safe lower limit of drilling mud density calculated by both the traditional and modified Mohr-Coulomb criteria. The result demonstrates that the mud density window calculated by the new criterion is narrower, which reveals the applicability of the modified Mohr-Coulomb criterion in the analysis of wellbore stability in hydrate formation.     

Hydrogen production via sulfur-based thermochemical cycles: Part 1: Synthesis and evaluation of metal oxide-based candidate catalyst powders for the sulfuric acid decomposition step

The present work concerns the synthesis of various single and mixed oxide materials and their study as catalysts for the sulfuric acid dissociation reaction via which the production of SO₂ and O₂ is achieved. This is the most energy intensive step of sulfur-based thermochemical cycles for the production of hydrogen. Commercial (i.e. FeO, Fe₃O₄, Fe₂O₃, CuO, Cr₂O₃, γ-Al₂O₃, Pt/γ-Al₂O₃) and in-house binary and ternary compositions of the Cu-Fe-Al system as well as Fe-Cr mixed oxide materials prepared by the Solution Combustion Synthesis (SCS) technique were comparatively tested. The materials were studied in powder form, in a fixed bed reactor at 850 °C and ambient pressure. The feedstock was concentrated liquid sulfuric acid (95-98% wt) and all tests were performed at a Liquid Hourly Space Velocity-LHSV of 50-52 h⁻¹. It was found that systems of both in-house synthesized mixed oxide families (Cu-Fe-Al and Fe-Cr) with proper composition could achieve SO₃ conversions comparable to that of the reference Pt/γ-Al₂O₃ system, being at the same time much less expensive. The results, in combination with characterization results of fresh and spent catalysts are employed to identify possible mechanisms of the reaction and streamline the synthesis of more efficient catalytic systems.     

统计假设检验技术在优化产品测试方法中的应用

在PET产品特性黏度测试方法优化过程中,应用几种统计假设检验对不同试验方案下的试验数据可靠性、准确性进行比较,从而选出最佳的试验方案。     

A DFT study on the addition and abstraction reactions of thiourea with hydroxyl radical

The thiourea + ^? hydrogen atom transfer mechanism has been investigated theoretically for the first time. The objectives of the study OHhave been to elucidate the nature of the reaction species, energetic, geometric, electronic and reaction kinetic properties for the reaction. The study has been performed with the DFT/BHHLYP, DFT/ωB97X-D and DFT/M06-2X methods, by using the 6-311++G(3df,2p) basis set. The study has been performed in vacuo and in aqueous media. The results of the study indicate that the ^?OH addition mechanism is thermodynamically favored to the direct H-atom abstraction mechanism. The activation energy is dependent on the media; it is higher in water solution than in vacuo. The direct H-atom abstraction mechanism is kinetically favored with respect to the ^?OH addition mechanism in both media, suggesting that the reaction of thiourea with ^?OH most likely proceeds through this mechanism. In water solution, the estimated apparent rate constant is close to the experimentally determined value. The spin density distribution on the thiyl is delocalized throughout the S–C–N region. The bond dissociation enthalpy is overestimated, with respect to experimentally available data, but suggests that H-atom transfer is easier in non-polar medium than in polar medium.     

A distance correlation index of spatial dependence for compositional data

Geographical data in economic, social or environmental sciences are usually recorded as compositions, i.e. relative frequencies, and a common inquiring problem concerns the analysis of these data over different geographical regions. In the present paper we define a new statistical test to verify spatial dependence of such geographical distributions based on distance correlation, a recently introduced measure of dependence between random vectors. The proposed index computes the non-linear spatial distance between distributions and can be applied on compositional frequency distributions. Simulations and an application on Italian electoral data are presented, to illustrate the capabilities of the proposed test to detect spatial dependence.