Chemical Additives for Corrosion Control in Desalination Plants

The addition of chemical additives has been considered as a standard operation in water treatment systems. This chapter discusses the chemical additives used for the control of corrosion in desalination systems. Specifically, corrosion inhibitors for various metallurgies, biocides, and oxygen scavengers are covered. The pros and cons of the additive chemicals have been highlighted. The need to utilize green corrosion inhibitors based on plants and ionic liquids materials have been emphasized. This class of materials are environmentally friendly, cheap, and readily available

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18–49, 50–69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population

Hydration of C₄AF in the presence of artificial CaSO₄ and lime

292-296The ferrite phase consists of about 8-13 wt% portland cement. This phase has received little attention with regard to its hydration. The aim of present investigation is to synthesize the ferrite phase and study the rate of hydration in the presence of CaSO4 and CaO up to 28-days in suspension. This study is followed by the determination of the free lime as well as combined water con tents and the hydration products by the XRD analysis. The results revealed that whatever the amount of CaSO4 the monosulphate AFm was the only phase formed from 6 h up to 28-days and the ettringite AFt was not formed. In the presence of 1 mol CaSO4 and 2 mol CaO, the monosulphate AFm with carboaluminate was the dominant phase at 28-days. When the amount of CaSO4 was increased to 3 mol with the same amount of lime the hydration was retarded in comparison with that containing 1 mol of CaSO4. Very small amount of sulphoaluminate ferrite hydrate was formed with residual reactants such as C4AF,CaSO4 and Ca(OH)2

Characteristics of blended cements containing nano-silica

AbstractThe aim of the present work is to evaluate the effect of nano-silica (NS) on physico-chemical, compressive and flexural strengths of OPC-granulated slag blended cement pastes and mortars. Different mixes were made with various amounts of NS, OPC and granulated blast-furnace slag (GBFS) and hydrated for 3, 7, 28 and 90days. The hydration behavior was followed by estimation of free lime (FL) and combined water content at different curing ages. The required water for standard consistency, setting times and compressive strength was also determined. The results obtained were confirmed by XRD, DTA, IR and SEM techniques. The required water for standard consistency and setting times increases with NS content due to the presence of 1% of superplasticizer. As the NS content increases the values of both FL and pH decrease. The compressive and flexural strengths of cement mortars containing NS are higher than those of control OPC–GBFS mix (M3). As the NS content increases above 4mass% NS, compressive and flexural strengths of OPC–GBFS–NS blends decrease but still more than those of the control samples (M3). The results of XRD, DSC, IR and SEM examinations are in good harmony with each other and with chemical analyses. The composite OPC–GBFS–NS cements containing 45mass% of GBFS and 3–4mass% of NS possess the highest improvement of mechanical properties, hydration kinetics and microstructure of hardened cement pastes and mortars

Durability of composite cements containing granulated blast-furnace slag and silica nano-particles

88-100<span style="font-size:11.0pt;mso-bidi-font-size: 10.0pt;font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" letter-spacing:-.1pt;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"="" lang="EN-GB">The durability of concrete has been a major concern of civil engineering. Chemical attack caused by aggressive waters is one of the factors causing damage to concrete. The effect of nano-silica (NS) on the durability of composite cement pastes and mortars cements containing granulated blast-furnace slag (GBFS) subjected to seawater attack has been studied. Chemically combined water, free lime, total chloride and sulphate contents, as well as bulk density, compressive and flexural strengths have been determined. The durability of cement pastes has been monitored using SEM and XRD techniques. The obtained results indicate that NS improves the compressive and flexural strengths subjected to seawater up to 12 months. NS decreases the accessibility of SO42- and Cl- to penetrate the pore system, hence the total sulfate and total chloride contents decrease. The accumulation of additional hydration products within the pore system enhances the densification of cement paste matrix to form closed and compact structure with narrow pores.</span

Mutual inter-regulation between iNOS and TGF-β1: Possible molecular and cellular mechanisms of iNOS in wound healing.

Abnormal wound healing with excessive scarring is a major health problem with socioeconomic and psychological impacts. In human, chronic wounds and scarring are associated with upregulation of the inducible nitric oxide synthase (iNOS). Recently, we have shown physiological regulation of iNOS in wound healing. Here, we sought to investigate the possible mechanistic role of iNOS in wound healing using biochemical and immunohistochemical assays. We found: (a) iNOS is the main source of wound nitric oxide (NO), (b) NOS inhibition in the wound, downregulated iNOS protein, mRNA and enzymatic activity, and reduced wound NO, and (c) iNOS inhibition resulted in delayed healing at early time points, and excessive scarring at late time points. Furthermore, molecular and cellular analysis of the wound showed that iNOS inhibition significantly (P < 0.05) increased TGF-β1 mRNA and protein levels, fibroblasts and collagen deposition. These latter findings suggest that iNOS might be exerting its action in the wound by signaling through TGF-β1 that activates wound fibroblasts to produce excessive collagen. Our current findings provide further support that iNOS is crucial for physiological wound healing, and suggest that dysregulation of iNOS during the inflammatory phase impairs healing, and results in disfiguring post-healing scarring. Thus, the mutual feedback regulation between iNOS and TGF-β1 at the gene, protein and functional levels might be the mechanism through which iNOS regulates the healing. Monitoring and maintenance of wound NO levels might be important for healing and avoiding long-term complications in susceptible people including patients with diabetic wounds, venous ulcers or keloid prone