Investigation into adsorption equilibrium and thermodynamics for water vapor on montmorillonite clay

The isothermal adsorption curves for water vapor on montmorillonite were measured by a gravimetric adsorption system. Dent's model was employed to estimate the adsorption behaviors of water vapor on primary adsorption sites and secondary adsorption sites. The thermodynamics analysis of water vapor adsorption was performed. At low vapor pressure region, primary adsorption predominates, and with increasing vapor pressure, secondary adsorption becomes notable. Primary adsorption sites have an evidently stronger adsorption affinity than secondary adsorption sites. With increasing vapor pressure, Gibbs free energy variation rapidly increases and then reduces slowly. Although increasing vapor pressure raises adsorption spontaneity on primary adsorption sites, the enhancement in vapor pressure decreases the spontaneity of water vapor adsorption on secondary adsorption sites. As adsorbed loading increases, isosteric heat of adsorption and entropy loss decrease first and then increase quickly. The gradually growing water clusters are responsible for the increase of entropy loss at late stage.     

Rip currents near coastal structures in Lake Michigan: Characterization and assessment for warnings

Rip currents near coastal structures commonly occur in Lake Michigan in the Great Lakes region of the United States. Lack of timely warning due to undocumented characteristics of rip currents and no assessment tool can contribute to tragic drownings incidents. In this paper, we characterized rip current occurrences near breakwater structures and developed an assessment tool for providing timely rip current warnings to beachgoers at the study site, City of Port Washington, WI. Characteristics of rip currents near the structure were observed from field measurements or visual images. Deflection rip currents had speeds of ～ 0.2 m/s and lasted for several hours. The rip current occurrences were associated with environmental proxies. It was found that rip currents can occur even when the water appears calm near the structure. A Structure Rip Checklist and Assessment Matrix (SRiCAM) with a four-tiered risk was developed and validated using observations. Furthermore, the SRiCAM was integrated into cyberinfrastructure with a data contingency plan to provide real-time warnings to the public. The applicability of the SRiCAM to other locations across Lake Michigan was further tested and results are promising. Overall, the SRiCAM has the potential to be widely extended to foster recreational water safety and resilience to rip current hazards in the Great Lakes.     

Tribological behavior of TSP reinforced WC matrix composites sliding against N80 casing steel lubricated by water-based drilling fluid

The friction and casing wear behavior of TSP composites sliding against N80 casing steels and lubricated by drilling fluids were investigated. It was found that the water-based drilling fluid reduced friction coefficient and casing wear effectively. The surface lubricating films with iron oxide grains formed on the surface of casings are all observed for the three hardbandings, while the discontinuous lubrication film of N3 alloy might account for the higher casing wear therewith. The lowest friction coefficient and casing wear was recorded for TSP composite under load of 10–130 N. This is dependent on the adsorbed lubricating liquid on the rubbing surface and the formation of height difference between the TSP part and the WC matrix part.     

Niobium as a new binder for polycrystalline diamond (PCD) sintered via High Pressure-High Temperature (HPHT)

In this research, the effect of adding 2.5, 5.0 and 10 wt% niobium (Nb) as a binding agent was investigated for High Pressure-High Temperature (HPHT) sintering of polycrystalline diamond (PCD). Samples were sintered at 1750 °C and 7.7 GPa. Detailed characterization of the as-sintered materials revealed a uniform dispersion of the Nb additives in the diamond matrix and no interfacial cracking was observed. Higher concentration of binder increased tendency to intergranular failure. The formation of NbC and NbC_0.84 phases after sintering was identified, indicating that some of the matrix carbon may have undergone graphitization.     

降雨入渗及地震作用下边坡稳定性研究

边坡滑坡给社会经济和人民生命安全带来了巨大威胁，降雨和地震是边坡滑坡的两大诱因。以云南省某矿山边坡作为研究对象，取样后在室内进行岩石力学实验，得到后期工作所需的岩石力学参数，利用霍克布朗准则推导出岩体的力学参数，运用理论计算和数值模拟分析降雨和地震对边坡稳定性影响，结果表明：1）在降雨入渗作用下，边坡出现滑坡主要是静水压力造成的；2）在地震作用下，当地震峰值加速度为0.1g时，有效塑性区主要位于边坡中下部，当增大地震峰值加速度，其范围向坡脚移动，当加速度为0.3g时，塑性区出现贯通趋势。     

Flotation performance and adsorption mechanism of novel 1-(2-hydroxyphenyl)hex-2-en-1-one oxime flotation collector to malachite

A novel collector 1-(2-hydroxyphenyl)hex-2-en-1-one oxime (HPHO) was synthesized from 2-hydroxy acetophenone and butyraldehyde. Its flotation performance and adsorption mechanism to malachite were investigated by flotation test, zeta potential, Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis techniques. Compared with benzohydroxamic acid (BA), 1-(2-hydroxyphenyl)ethan-1-one oxime (HPEO) and sodium isobutyl xanthate (SIBX), HPHO exhibited excellent collecting power to malachite without additional reagents, such as Na₂S regulator and methyl isobutyl carbinol (MIBC) frother. Results of zeta potential indicated that HPHO was coated on malachite surfaces through a chemisorption process. FTIR and XPS data gave clear evidence for the formation of Cu–oxime complex on malachite surfaces after HPHO adsorption through the linkage between C=C, –OH, N–OH group and Cu species.     

Use of conditioning time to investigate the mechanisms of interactions of selected fatty acids on hematite Part II laboratory investigations

It is the aim of this paper to examine the effects of conditioning time on the flotation of hematite using three technical grade fatty acid reagents as providing additional evidence on their mechanism of interaction with the hematite surface. Various mechanisms have been postulated as occurring as conditioning time is increased. Both physical (e.g. conditioning time and power input) and chemical (nature, dispersion and solubility of the adsorbing species) contribute to the mechanisms of attachment of collector. In this paper, the mechanism of attachment of oleate to hematite can be readily explained by chemisorption, but the mechanism of attachment of lauric acid appears to be physical adsorption at neutral pH. The flotation of hematite with a mixture of tallow-type fatty acids (palmitic, stearic and oleic acids) is very sensitive to conditioning time, and suggests that, even though flotation is very effective at short conditioning times, it is very susceptible to the presence of fines and their associated high surface areas. It is therefore obvious that both the physical and chemical conditions contribute to the mechanisms of adsorption of fatty acids on iron-containing oxide minerals and must be understood in order to optimise the flotation of these minerals in an industrial situation.     

Modeling surface water-groundwater interaction in arid and semi-arid regions with intensive agriculture

In semi-arid and arid areas with intensive agriculture, surface water-groundwater (SW-GW) interaction and agricultural water use are two critical and closely interrelated hydrological processes. However, the impact of agricultural water use on the hydrologic cycle has been rarely explored by integrated SW-GW modeling, especially in large basins. This study coupled the Storm Water Management Model (SWMM), which is able to simulate highly engineered flow systems, with the Coupled Ground-Water and Surface-Water Flow Model (GSFLOW). The new model was applied to study the hydrologic cycle of the Zhangye Basin, northwest China, a typical arid to semi-arid area with significant irrigation. After the successful calibration, the model produced a holistic view of the hydrological cycle impact by the agricultural water use, and generated insights into the spatial and temporal patterns of the SW-GW interaction in the study area. Different water resources management scenarios were also evaluated via the modeling. The results showed that if the irrigation demand continuous to increase, the current management strategy would lead to acceleration of the groundwater depletion, and therefore introduce ecological problems to this basin. Overall, this study demonstrated the applicability of the new model and its value to the water resources management in arid and semi-arid areas.     

It is in the box! Improving the usability and benefits of surgical safety checklists – A feasibility study

Up to 50% of preventable hospital medical errors occur in or after visiting an operating theater in the United States. To address this issue, hospitals use a Surgical Safety Checklist (SSC), which can reduce complications and mortality rates when used systematically. To execute it, surgeons read aloud from a poster hanging on a wall. However, studies report usability issues with posters and often surgeons execute the checklist from memory, which can reduce completion rates at the expense of patient safety. We present a novel approach to increase the SSC's usability in view of improving patient safety. Our DigitalChecklistBox displays the SSC directly on a patient's surgical drape and enables surgeons to navigate through the checklist using hand gestures. Evaluated with 10 surgeons, it increased the checklist elements' readability and navigation and brought additional functionalities to limit the number of missed elements.     

预应力锚索锚固力监测点经济高效布设方法研究

预应力锚索锚固力监测点合理布设是提高边坡稳定性监测可靠性的重要手段，在确保边坡稳定安全的同时，可最大程度上节省工程监测成本。现阶段预应力锚索锚固力监测点布设方案设计多依赖工程经验，具有很强的盲目性并且监测成本较大，尤其对于大型高陡边坡，由于挖方量和边坡加固工程量巨大，如何实现高陡边坡预应力锚索锚固力监测点经济高效布设，保证边坡安全高效监测是目前亟需解决的问题。以广东省江门市迎宾西路某高边坡为研究背景，通过研究锚索的群锚效应和锚索失效后的影响范围，确定了监测点之间的合理布设间距。构建了边坡三维模型，通过数值计算，模拟高边坡开挖全过程，由数值计算结果分析边坡开挖过程中变形失稳的潜在危险区域，进行监测点选择型布设。通过上述方法，实现了该段高陡路堑边坡预应力锚索锚固力监测点的经济高效布设。研究表明：基于群锚效应与三维数值模拟方法，提出的预应力锚索合理布设间距与开挖过程中潜在危险区域重点监测相结合的综合布设优化方案，可合理利用材料和空间、大幅节省监测成本，实现边坡的经济、高效监测。研究成果为高陡路堑边坡稳定性监测点合理布设提供了一种新的思路。