A Multiplexed Four Channel On-Line Iodine Monitor

Abstract

A robust autonomous system is described for the spectrophotometric determination of aqueous elemental iodine in multiple flowing process streams. The quantitative methodology uses characteristic absorbance at 460 nm, corrected for baseline drift using absorbance at 600 nm. Linear dynamic ranges of 0.2 - 25 mg/L, 0.4 - 45 mg/L, and 2 - 250 mg/L have been attained using path lengths of 1 cm, 5 cm, and 10 cm respectively. The multiplexed iodine monitor has proven capable of continuous operation for periods of up to eighteen months.     

A randomized double‐blind crossover study of indoor air filtration and acute changes in cardiorespiratory health in a First Nations community

Few studies have examined indoor air quality in First Nations communities and its impact on cardiorespiratory health. To address this need, we conducted a crossover study on a First Nations reserve in Manitoba, Canada, including 37 residents in 20 homes. Each home received an electrostatic air filter and a placebo filter for 1 week in random order, and lung function, blood pressure, and endothelial function measures were collected at the beginning and end of each week. Indoor air pollutants were monitored throughout the study period. Indoor PM_2.5 decreased substantially during air filter weeks relative to placebo (mean difference: 37 μg/m³, 95% CI: 10, 64) but remained approximately five times greater than outdoor concentrations owing to a high prevalence of indoor smoking. On average, air filter use was associated with a 217‐ml (95% CI: 23, 410) increase in forced expiratory volume in 1 s, a 7.9‐mm Hg (95% CI: ?17, 0.82) decrease in systolic blood pressure, and a 4.5‐mm Hg (95% CI: ?11, 2.4) decrease in diastolic blood pressure. Consistent inverse associations were also observed between indoor PM_2.5 and lung function. In general, our findings suggest that reducing indoor PM_2.5 may contribute to improved lung function in First Nations communities.     

Multi-scale mechanistic modelling of the host defence in invasive aspergillosis reveals leucocyte activation and iron acquisition as drivers of infection outcome

Aspergillus species are ubiquitous environmental moulds, with spores inhaled daily by most humans. Immunocompromised hosts can develop an invasive infection resulting in high mortality. There is, therefore, a pressing need for host-centric therapeutics for this infection. To address it, we created a multi-scale computational model of the infection, focused on its interaction with the innate immune system and iron, a critical nutrient for the pathogen. The model, parameterized using published data, was found to recapitulate a wide range of biological features and was experimentally validated in vivo. Conidial swelling was identified as critical in fungal strains with high growth, whereas the siderophore secretion rate seems to be an essential prerequisite for the establishment of the infection in low-growth strains. In immunocompetent hosts, high growth, high swelling probability and impaired leucocyte activation lead to a high conidial germination rate. Similarly, in neutropenic hosts, high fungal growth was achieved through synergy between high growth rate, high swelling probability, slow leucocyte activation and high siderophore secretion. In summary, the model reveals a small set of parameters related to fungal growth, iron acquisition and leucocyte activation as critical determinants of the fate of the infection.     

亚利桑那州立大学沃尔特·克朗凯特新闻与大众传播学院

为了振兴凤凰城市中心,亚利桑那州为亚利桑那州立大学的一个新建项目举办了几次跨越"毕业领奖台"的优秀设计.楼高6层,20,903m<'2>(295,000平方英尺)的沃尔特·克朗凯特新闻与大众传播学院建筑是其中快速设计、各方协力实施的典范.该建筑由建筑师Ehrlich、HDR建筑公司和和总承包商SUNDT建设公司通力合作,创造了在二十二个月内完成设计并交付使用的记录.     

一种新颖的双桥矩阵变换器控制策略

矩阵变换器是一种AC/AC变换器,它具有正弦输入电流、正弦输出电压、能量双向流动及体积小的优点,但存在着控制方法复杂,开关器件和保护元器件太多的问题.近年来提出的双桥矩阵变换器具有矩阵变换器的优点,同时其控制方法更简单,所用开关元件数目更少.论述了双桥矩阵变换器的原理,讨论了变换器的PWM控制策略以及基于线电压符号的换流方法,提出了整流级、逆变级单独控制,整流级开关频率为10kHz、逆变级开关频率为2kHz的新颖双桥矩阵变换器方案,给出了仿真和实验结果.     

Knight Mine reclamation: A study of revegetation difficulties in a semi-arid environment

ABSTRACT

An analysis of the difficulties associated with the re-establishment of reclamation vegetation on a dry mine site in southern Utah, U.S.A. is presented. Precipitation amounts, seed mix, seed bed preparation techniques, and soil properties all appeared to be adequate for vegetation establishment at the site. However, failure of repeated revegetation efforts in a redisturbed area of the mine site may have been due to higher soil salinity levels in the area, which may Have given Kochia scoparia an initial competitive advantage. Lack of soil moisture and allelopalhic effects due to the dense carpet of Kochia may have also contributed to the continued lack of revegetation success.     

On the Mechanism of Lubrication by Tricresylphosphate (TCP)—The Coefficient of Friction as a Function of Temperature for TCP on M-50 Steel

A pin-on-disk tribometer was used to study the coefficient of friction as a function of temperature for tricresylphosphate (TCP) on CVM M-50 tool steel under the following conditions: TCP was present in a liquid reservoir (bulk lubrication), and TCP was applied as a liquid layer directly to the disk (limited lubrication). Under limited lubrication conditions, experiments were performed in dry (< 100 ppm H₂O) air, dry (< 20 ppm H₂O) nitrogen, dry nitrogen with the disks heated to 700°C, then cooled to room temperature before the TCP was applied and the measurements made (preheated disks), and moist nitrogen using preheated disks. The coefficient of friction decreased at a characteristic temperature, T_r T_r values observed were: 265°C for bulk lubrication conditions in dry air, 225°C for limited lubrication conditions in dry air, and 215°C for limited lubrication conditions in dry nitrogen. The use of preheated disks produced a sharp failure temperature at 218°C which was taken as the temperature about which the behavior of TCP should be judged. X-ray photoelectron spectroscopy confirmed the presence of phosphate on the surface of TCP-lubricated iron pins. Depth profile studies support the suggestion that a chemical reaction occurs between the TCP and the metal surface at T_r.