Modelling chloroform in indoor swimming pool air and water: the influences of internal air circulation and occupants.

The release of chloroform from water to air in an indoor swimming pool (ISP) exhibits complex physicochemical interactions among many variables, including environmental conditions, occupant activities, and geometry of the ISP. By combining the relevant variables, a structured mathematical model, the double-layer air compartment (DLAC) model, was developed to predict the level of chloroform in ISP air. A physical parameter, the indoor airflow recycle ratio (R), was incorporated into the DLAC model due to internal airflow circulation resulting in the ISP structural configuration. The theoretical R-value for a specific indoor airflow rate (vy) can be found by fitting the predicted residence time distribution (RTD) to the simulated RTD from computational fluid dynamics (CFD), showing a positive linear relationship with vy. The mechanical energies induced by occupant activities were converted into a lumped overall mass-transfer coefficient to account for the enhanced mass transfer of chloroform from the water into the air and mixing in ISP air. The DLAC model predicted that chloroform air concentrations were statistically less accurate without considering the influence of R compared with the online open-path Fourier transform infrared measurements. A novel index, the magnitude of emission (MOE) from swimmers, was linked to the level of chloroform in ISP water. The capability of the DLAC model associated with the MOE concept may facilitate upgrading the hygiene management of ISPs, including the ability to administer necessary chlorine additives in pool water and monitor the chloroform in ISP air.

Extending Theory of Planned Behavior to Understand Service-Oriented Organizational Citizen Behavior.

The financial crisis of 2007-2008 and the COVID-19 pandemic have caused many enterprises to suffer great losses. Thus, companies have to take measures such as pays cut, furloughs, or layoffs, which caused dissatisfaction among employees and triggered labor disputes. Therefore, this study explores the service-oriented organizational citizenship behavior based on the decomposed theory of planned behavior in order to understand the behavioral intentions of employees through their mental states, job attitudes, subjective norms, and perceived behavioral control. This study conducted questionnaire surveys for employees in different industries, collected 281 valid questionnaires, and applied Structural Equation Model for the analysis. The results show: (1) employees believe organizational justice in the organization is important, and when they feel treated fairly, their job attitudes and beliefs are enhanced. (2) Employees' job attitudes and beliefs support service-oriented organizational citizenship behavior, in other words, they have positive job attitudes and beliefs and will actively provide better service to customers. (3) When employees are treated reasonably and fairly by the organization and have positive job attitudes (job satisfaction and organizational commitment) and perceived behavior control, their spontaneous service-oriented organizational citizenship behavior is stimulated, thus increasing organizational development.

Enhanced Activity of Hierarchical Nanostructural Birnessite-MnO2-Based Materials Deposited onto Nickel Foam for Efficient Supercapacitor Electrodes.

Hierarchical porous birnessite-MnO2-based nanostructure composite materials were prepared on a nickel foam substrate by a successive ionic layer adsorption and reaction method (SILAR). Following composition with reduced graphene oxide (rGO) and multiwall carbon nanotubes (MWCNTs), the as-obtained MnO2, MnO2/rGO and MnO2/rGO-MWCNT materials exhibited pore size distributions of 2-8 nm, 5-15 nm and 2-75 nm, respectively. For the MnO2/rGO-MWCNT material in particular, the addition of MWCNT and rGO enhanced the superb distribution of micropores, mesopores and macropores and greatly improved the electrochemical performance. The as-obtained MnO2/rGO-MWCNT/NF electrode showed a specific capacitance that reached as high as 416 F·g-1 at 1 A·g-1 in 1 M Na2SO4 aqueous electrolyte and also an excellent rate capability and high cycling stability, with a capacitance retention of 85.6% after 10,000 cycles. Electrochemical impedance spectroscopy (EIS) analyses showed a low resistance charge transfer resistance for the as-prepared MnO2/rGO-MWCNT/NF nanostructures. Therefore, MnO2/rGO-MWCNT/NF composites were successfully synthesized and displayed enhanced electrochemical performance as potential electrode materials for supercapacitors.

Recycling dredged harbor sediment to construction materials by sintering with steel slag and waste glass: Characteristics, alkali-silica reactivity and metals stability.

This work recovered the dredged sediment around Kaohsiung Harbor, Taiwan, for preparing lightweight aggregates (LWA), of which physicochemical properties as affected by the addition of basic-oxygen-furnace (BOF) slag and waste glass were investigated. LWA properties included water absorption, particle density, compressive strength, shrinkage, and microstructure of sintered pellets were evaluated to ensure feasibility of dredged harbor sediment reutilization technique. Results showed that adding appropriate amount of glass powders (~7%) to the mixtures of sediment and slag significantly reduced the water absorption (as low as 2.2%) of the sintered pellets and increase the compressive strength (as high as 23.1 MPa) of LWA, which were found to be controlled by open porosity and shrinkage. Excessive addition of glass (>10%) led to increase in internal pore sizes of the sintered pellets, and thus reduced the compressive strength. The alkali-silica reactivity (ASR) of the LWA was innocuous according to the ASTM C289 test. Sintering and glass addition improved the stability of heavy metal and environmental compatibility of the LWA. The recycling of waste sediment, slag, and glass for LWA production can provide an alternative for the disposal of dredge harbor sediment and has positive impact on waste reduction, which not only can reduce secondary contamination to the environment, but also can contribute to circular economy.

Experimental study of fuel sootiness effects on flashover.

Previous fire safety studies have demonstrated that flashover can result in severe injure and death and heat radiating back to a fuel is an important mechanism. Fuel sootiness dominates in radiative heat transfer. However, empirical correlations from previous investigations did not consider the fuel sootiness but nevertheless generated reasonably good predictions of flashover. In this study, a series of experiments was employed to examine fuel sootiness effects on flashover. The fuels used, in the order of their sootiness, were gasoline, n-hexane, iso-propanol and methanol. These fuels were filled in circular pans 100-320 mm in diameter to generate fires with different heat release rates and levels of sootiness. The pans were in 1/3 the size of the ISO 9705 test chamber. After ignition, the heat release rate (HRR), temperature inside the chamber, as well as heat flux on the floor and time to flashover (t(fo)) were determined. Experimental data show that HRR at flashover and t(fo) were strongly corrected and their relationship was independent of the fuel burned. Although heat feedback to the floor increased as fuel sootiness increased, consequently enhancing the burning of sooty fuels, flashover occurs only when the HRR at flashover criterion is reached.

Orientation effect on cone calorimeter test results to assess fire hazard of materials.

A cone calorimeter can provide material "reaction to fire" information for use in evaluating the fire hazard of materials. Two orientations can be selected, vertical or horizontal, depending on the geometry of materials in their final use. However, most fire models and material evaluation reports fail to consider the effects of the orientation and applied the horizontal case data. To assess the validity of using data with "horizontal" samples for further applications, a systematic experimental was performed using materials including PMMA, wooden products and polystyrene foams. Besides critical heat flux for ignition, other "reaction to fire" material properties were measured, including ignition time, ignition temperature, heat release rate history and mass loss rate when exposed to three heating irradiances, namely 15, 30 and 50 kW/m(2). For the horizontal orientation in comparison to the vertical orientation, the study data reveal relatively constant temperature distribution before ignition, lower critical heat flux for pilot ignition, shorter time to ignition, lower peak heat release rate, identical total heat release, longer burning time and almost identical combustion completeness for all the tested materials except polystyrene foams. Ignition temperature displaced no clear trend. Vertical orientation tests are consequently recommended for evaluating material fire performance.