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This paper provides an analytical assessment of the feasibility of wind energy for Saudi Arabia's envisioned NEOM city, which plans to use only renewable energy. A probability density function was fit to winds simulated for the NEOM region during 2014‐2018. Using this distribution, the optimal wind turbine was selected as the one with the largest capacity factor and smallest levelized cost of energy (LCOE). Financial, environmental, and risk analysis of a wind farm consisting of 100 of these units was also performed. A Weibull distribution determined by changing the shape and scale parameters to minimize the mean squared error offered the best fit to the measured wind speeds at this location. The estimated power density showed that the NEOM site warrants a Class 3 classification, which means wind energy systems would be suitable for commercial operation. A 3.2‐MW wind turbine, which is optimal for this location, has a capacity factor varying from 31.9% to 41.4% and LCOE that ranges from 6.99¢ to 8.32¢ per kWh. The 320‐MW wind farm has a positive net present value, a simple payback period of 13.8 years, and a LCOE of 6.6¢ per kWh. By installing this farm, potential annual savings of CO2 are around 106 metric tons. [ABSTRACT FROM AUTHOR]

This paper examines the bio-derived stabilization of sand-only or sand-plus-silt soils using an extracted bacterial enzyme application to achieve induced calcite precipitation (ICP). As compared to conventional microbial induced calcite precipitation (MICP) methods, which use intact bacterial cells, this strategy that uses free urease catalysts to secure bacterial enzyme–induced calcite precipitation (BEICP) appears to offer an improved means of bio-stabilizing silty-sand soils as compared to that of MICP processing. Several benefits may possibly be achieved with this BEICP approach, including bio-safety, environmental, and geotechnical improvements. Notably, the BEICP bio-stabilization results presented in this paper demonstrate (i) higher rates of catalytic urease activity, (ii) a wider range of application with sand-plus-silt soil applications bearing low-plasticity properties, and (iii) the ability to retain higher levels of soil permeability after BEICP processing. Comparative BEICP versus MICP results for sand-only systems are presented, along with BEICP-based results for stabilized soil mixtures at 90:10 and 80:20 percentile sand:silt ratios. This BEICP method's ability to obtain unconfined compressive strength results in excess of 1000 kPa with sand-plus-silt soil mixtures is particularly noteworthy. [ABSTRACT FROM AUTHOR]

Furthermore, the discussers' equation presents a relationship between UCS and the porosity/cement index that are suitable for portland cement stabilized soils via mixing method. Soils and portland cement are mixed uniformly at their dry states during the stabilization process, whereas the biocementation stabilization adopts a percolation circulation technique that solidifies the specimen column from top to bottom. Portland cement stabilization and biocementation stabilization techniques' working mechanisms are different and equations developed for predicting UCS of portland cement stabilized soils may not be directly applicable to soils stabilized using biocementation techniques. [Extracted from the article]

Addresses the prevalence of providing psychotherapy over the Internet. Ethical issues surrounding the phenomenon; Factors to be considered by clinicians deciding to work online; Opportunity of the prospect of online mental health care treatment.

Wastewater disinfection is practiced with the goal of reducing risks of human exposure to pathogenic microorganisms. In most circumstances, the efficacy of a wastewater disinfection process is regulated and monitored based on measurements of the responses of indicator bacteria. However, inactivation of indicator bacteria does not guarantee an acceptable degree of inactivation among other waterborne microorganisms (e.g., microbial pathogens). Undisinfected effluent samples from several municipal wastewater treatment facilities were collected for analysis. Facilities were selected to provide a broad spectrum of effluent quality, particularly as related to nitrogenous compounds. Samples were subjected to bench-scale chlorination and dechlorination and UV irradiation under conditions that allowed compliance with relevant discharge regulations and such that disinfectant exposures could be accurately quantified. Disinfected samples were subjected to a battery of assays to assess the immediate and long-term effects of wastewater disinfection on waterborne bacteria and viruses. In general, (viable) bacterial populations showed an immediate decline as a result of disinfectant exposure; however, incubation of disinfected samples under conditions that were designed to mimic the conditions in a receiving stream resulted in substantial recovery of the total bacterial community. The bacterial groups that are commonly used as indicators do not provide an accurate representation of the response of the bacterial community to disinfectant exposure and subsequent recovery in the environment. UV irradiation and chlorination/dechlorination both accomplished measurable inactivation of indigenous phage; however, the extent of inactivation was fairly modest under the conditions of disinfection used in this study. UV irradiation was consistently more effective as a virucide than chlorination/dechlorination under the conditions of application, based on measurements of virus (phage) diversity and concentration. Taken together, and when considered in conjunction with previously published research, the results of these experiments illustrate several important limitations of common disinfection processes as applied in the treatment of municipal wastewaters. In general, it is not clear that conventional disinfection processes, as commonly implemented, are effective for control of the risks of disease transmission, particularly those associated with viral pathogens. Microbial quality in receiving streams may not be substantially improved by the application of these disinfection processes; under some circumstances, an argument can be made that disinfection may actually yield a decrease in effluent and receiving water quality. Decisions regarding the need for effluent disinfection must account for site-specific characteristics, but it is not clear that disinfection of municipal wastewater effluents is necessary or beneficial for all facilities. When direct human contact or ingestion of municipal wastewater effluents is likely, disinfection may be necessary. Under these circumstances, UV irradiation appears to be superior to chlorination in terms of microbial quality and chemistry and toxicology. This advantage is particularly evident in effluents that contain appreciable quantities of ammonia-nitrogen or organic nitrogen. [ABSTRACT FROM AUTHOR]