scholarly journals The Use of TiO2 as a Disinfectant in Water Sanitation Applications

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1641
Author(s):  
Rafael Magaña-López ◽  
Paloma I. Zaragoza-Sánchez ◽  
Blanca E. Jiménez-Cisneros ◽  
Alma C. Chávez-Mejía
Keyword(s):  
Protein Interactions ◽  
Advanced Oxidation Processes ◽  
Water Disinfection ◽  
Health Concern ◽  
Actual State ◽  
Attractive Alternative ◽  
Waterborne Diseases ◽  
Satisfactory Description ◽  
Potential Benefits ◽  
Evaluation Parameters

Waterborne diseases produced by organisms of public health concern are prevalent worldwide, continuing to cause deaths annually. Conventional disinfectants (ozone, UV radiation, chlorine) have been insufficient in providing safe water as many studies revealed. TiO2 is an attractive alternative to conventional methods because of its versatility and recently explored biocidal capacity due to advanced oxidation processes. The oligodynamic effect that TiO2 seems to have on some microorganisms consists of effective lipid hyper oxidation of microorganism membranes, as well as protein interactions that lead to the alteration of the internal conditions and the inhibition of metabolic processes that eventually lead to their lysis. Nevertheless, a satisfactory description of other organisms is necessary to complete the disinfectant–organism interaction, and then the subsequent evaluation parameters of sanitation should proceed. In addition, solutions for feasibility, standardization of results for achieving consistent results and defined applications, lower costs, scalability, and security after its application need to be studied. Understanding its usage implies knowing the actual state of the art and its limitations for water disinfection purposes, as well as the potential benefits that overcoming such limitations would provide, thus allowing the possibility of establishing it as a feasible and popular technology.

Excystation ofCryptosporidium parvumat temperatures that are reached during solar water disinfection

Parasitology ◽  
2009 ◽  
Vol 136 (4) ◽  
pp. 393-399 ◽  
Author(s):  
H. GÓMEZ-COUSO ◽  
M. FONTÁN-SAINZ ◽  
J. FERNÁNDEZ-ALONSO ◽  
E. ARES-MAZÁS
Keyword(s):  
Solar Radiation ◽  
Cryptosporidium Parvum ◽  
Gradual Increase ◽  
Water Disinfection ◽  
Waterborne Diseases ◽  
Pathogenic Microorganisms ◽  
Simple Method ◽  
Solar Water ◽  
Solar Water Disinfection ◽  
Notable Increase

SUMMARYSpecies belonging to the generaCryptosporidiumare recognized as waterborne pathogens. Solar water disinfection (SODIS) is a simple method that involves the use of solar radiation to destroy pathogenic microorganisms that cause waterborne diseases. A notable increase in water temperature and the existence of a large number of empty or partially excysted (i.e. unviable) oocysts have been observed in previous SODIS studies with water experimentally contaminated withCryptosporidium parvumoocysts under field conditions. The aim of the present study was to evaluate the effect of the temperatures that can be reached during exposure of water samples to natural sunlight (37–50°C), on the excystation ofC. parvumin the absence of other stimuli. In samples exposed to 40–48°C, a gradual increase in the percentage of excystation was observed as the time of exposure increased and a maximum of 53·81% of excystation was obtained on exposure of the water to a temperature of 46°C for 12 h (versus8·80% initial isolate). Under such conditions, the oocyst infectivity evaluated in a neonatal murine model decreased statistically with respect to the initial isolate (19·38%versus100%). The results demonstrate the important effect of the temperature on the excystation ofC. parvumand therefore on its viability and infectivity.

scholarly journals Legionella pneumophila and Protozoan Hosts: Implications for the Control of Hospital and Potable Water Systems

Pathogens ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 286 ◽  
Author(s):  
Muhammad Atif Nisar ◽  
Kirstin E. Ross ◽  
Melissa H. Brown ◽  
Richard Bentham ◽  
Harriet Whiley
Keyword(s):  
Legionella Pneumophila ◽  
Distribution Systems ◽  
Water Distribution ◽  
Potable Water ◽  
Water Systems ◽  
Water Disinfection ◽  
Health Concern ◽  
Waterborne Pathogen ◽  
Microbial Biofilms ◽  
Pontiac Fever

Legionella pneumophila is an opportunistic waterborne pathogen of public health concern. It is the causative agent of Legionnaires’ disease (LD) and Pontiac fever and is ubiquitous in manufactured water systems, where protozoan hosts and complex microbial communities provide protection from disinfection procedures. This review collates the literature describing interactions between L. pneumophila and protozoan hosts in hospital and municipal potable water distribution systems. The effectiveness of currently available water disinfection protocols to control L. pneumophila and its protozoan hosts is explored. The studies identified in this systematic literature review demonstrated the failure of common disinfection procedures to achieve long term elimination of L. pneumophila and protozoan hosts from potable water. It has been demonstrated that protozoan hosts facilitate the intracellular replication and packaging of viable L. pneumophila in infectious vesicles; whereas, cyst-forming protozoans provide protection from prolonged environmental stress. Disinfection procedures and protozoan hosts also facilitate biogenesis of viable but non-culturable (VBNC) L. pneumophila which have been shown to be highly resistant to many water disinfection protocols. In conclusion, a better understanding of L. pneumophila-protozoan interactions and the structure of complex microbial biofilms is required for the improved management of L. pneumophila and the prevention of LD.

The Inactivation of Hepatitis a Virus and other Model Viruses by UV Irradiation

1993 ◽  
Vol 27 (3-4) ◽  
pp. 339-342 ◽  
Author(s):  
D. A. Battigelli ◽  
M. D. Sobsey ◽  
D. C. Lobe
Keyword(s):  
Uv Radiation ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Health Concern ◽  
Attractive Alternative ◽  
Type B ◽  
Log10 Reduction ◽  
Public Health Concern ◽  
Stirred Reactor ◽  
Virus Survival

Ultraviolet light is an attractive alternative to chemical disinfection of water, but little is known about its ability to inactivate important waterborne pathogens such as hepatitis A virus. Therefore, the sensitivity of HAV strain HM-175, coxsackievirus type B-5, rotavirus strain SA-11, and bacteriophages MS2 and øX174 to ultraviolet radiation of 254 nm wavelength in phosphate buffered water was determined. Purified stocks of the viruses were combined and exposed to collimated UV radiation in a stirred reactor for a total dose of up to 40 mW sec/cm2. Virus survival kinetics were determined from samples removed at dose intervals. The 4 log,10 (99.99%) inactivation doses for HAV, CB5, SA-11 and øX174 were 16, 29, 42 and 9 mW sec/cm2, respectively. MS2 exhibited the greatest resistance in buffered water with less than a 1 log10 reduction observed after exposure to 25 mW sec/cm2. A 15 mW sec/cm2 exposure induced a 7 log10 reduction of øX174, while inactivation of HAV, CB5 and SAll was intermediate, with at least 3 log10 reductions occurring after a 20 mW sec/cm2 exposure. The results of these experiments indicate that UV radiation can effectively inactivate viruses of public health concern in drinking water.

scholarly journals A Comparative Review of the Traditional and Modern Methods of Water Treatment

2020 ◽  
pp. 44-51
Author(s):  
Abayomi Olusegun Adeniyi
Keyword(s):  
Water Treatment ◽  
Tamil Nadu ◽  
Water Disinfection ◽  
Filter Method ◽  
Waterborne Diseases ◽  
Traditional Methods ◽  
Water Filter ◽  
Quality Of Water ◽  
Comparative Review ◽  
Modern Methods

Artificial pollution of groundwater may arise from either point or diffuse sources. Several different means to improve the microbial quality of water and reduce waterborne diseases have been documented around the world.  Traditional methods of water treatment include Filtration through winnowing sieve (used widely in Mali), Filtration through cloth (commonly used in villages in India, Mali and the southern part of Niger), Filtration through clay vessels (used in Egypt), filtration through plant material (commonly used in Tamil Nadu and Kerala, India) and Jempeng stone filter method (used in Bali, Indonesia). Modern methods of water treatment include Solar Water Disinfection (SODIS), LifeStraw, Nanofilter, Ceramic water filter, Bio-sand filter and Kanchan Arsenic filter. Comparatively, traditional methods of water treatment employ crude methods which have proved to be effective in relation to filtration but the modern methods make use of newer research technologies in the elimination of pathogens and toxic chemicals to make drinking water more potable and safe.

scholarly journals Neutral evolution test of the spike protein of SARS-CoV-2 and its implications in the binding to ACE2

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Georgina I. López-Cortés ◽  
Miryam Palacios-Pérez ◽  
Gabriel S. Zamudio ◽  
Hannya F. Veledíaz ◽  
Enrique Ortega ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Neutral Theory ◽  
Purifying Selection ◽  
Spike Protein ◽  
Health Concern ◽  
Neutral Evolution ◽  
Evolutionary Mechanisms ◽  
Theory Of Evolution ◽  
Selective Pressures

AbstractAs the SARS-CoV-2 has spread and the pandemic has dragged on, the virus continued to evolve rapidly resulting in the emergence of new highly transmissible variants that can be of public health concern. The evolutionary mechanisms that drove this rapid diversity are not well understood but neutral evolution should open the first insight. The neutral theory of evolution states that most mutations in the nucleic acid sequences are random and they can be fixed or disappear by purifying selection. Herein, we performed a neutrality test to better understand the selective pressures exerted over SARS-CoV-2 spike protein from homologue proteins of Betacoronavirus, as well as to the spikes from human clinical isolates of the virus. Specifically, Tyr and Asn have higher occurrence rates on the Receptor Binding Domain (RBD) and in the overall sequence of spike proteins of Betacoronavirus, whereas His and Arg have lower occurrence rates. The in vivo evolutionary phenomenon of SARS-CoV-2 shows that Glu, Lys, Phe, and Val have the highest probability of occurrence in the emergent viral particles. Amino acids that have higher occurrence than the expected by the neutral control, are favorable and are fixed in the sequence while the ones that have lower occurrence than expected, influence the stability and/or functionality of the protein. Our results show that most unique mutations either for SARS-CoV-2 or its variants of health concern are under selective pressures, which could be related either to the evasion of the immune system, increasing the virus’ fitness or altering protein – protein interactions with host proteins. We explored the consequences of those selected mutations in the structure and protein – protein interaction with the receptor. Altogether all these forces have shaped the spike protein and the continually evolving variants.

Acceptability of HIV Pre-exposure Prophylaxis (PrEP) and Opinions on PrEP Service Delivery Among Men Who Have Sex With Men in Singapore: A Qualitative Study

2019 ◽  
Vol 31 (2) ◽  
pp. 152-162 ◽  
Author(s):  
Chen Seong Wong ◽  
P. Arun Kumar ◽  
Christina M. Wong ◽  
Bryan C. H. Choong ◽  
Oliver Z. Lim ◽  
...  
Keyword(s):  
Hiv Transmission ◽  
Attractive Alternative ◽  
Patient Centered ◽  
Related Services ◽  
Qualitative Descriptive ◽  
Potential Benefits ◽  
Sex With Men ◽  
Exposure Prophylaxis ◽  
The Cost ◽  
Barriers And Motivators

PrEP is effective in preventing HIV transmission among at-risk HIV-negative MSM. A qualitative descriptive study with five focus group discussions (N = 33) involving a purposively recruited sample of Singaporean MSM was conducted from August 2016 to April 2017 to understand local perspectives on potential barriers and motivators to the adoption of PrEP, prior to the implementation of PrEP services in Singapore. Knowledge of PrEP was high, and many viewed PrEP as an attractive alternative to condoms for HIV prevention. Concerns about PrEP included the cost of PrEP and related services, the frequency of PrEP-related clinic visits, fear of side effects, and the stigma associated with using PrEP. Participants felt PrEP was best provided by MSM-friendly providers, and more needed to be done to increase awareness of the effectiveness of PrEP. Access to PrEP for MSM in Singapore has to be affordable, patient-centered, and convenient to maximize the potential benefits of PrEP.

scholarly journals Special Issue: Application of Advanced Oxidation Processes

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 867
Author(s):  
Ciro Bustillo-Lecompte ◽  
Jose Colina-Marquez ◽  
Lars Rehmann
Keyword(s):  
Treatment Option ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
Attractive Alternative ◽  
Special Issue ◽  
Complementary Treatment ◽  
Oxidation Processes ◽  
Conventional Methods

Advanced oxidation processes (AOPs) are nowadays not only considered as a complementary treatment option but as an attractive alternative to conventional methods [...]

scholarly journals Carbon nanotubes as antimicrobial agents for water disinfection and pathogen control

2018 ◽  
Vol 16 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Dan Liu ◽  
Yiqin Mao ◽  
Lijun Ding
Keyword(s):  
Carbon Nanotubes ◽  
Antimicrobial Agents ◽  
Microbial Control ◽  
Antimicrobial Properties ◽  
Water Disinfection ◽  
Water Remediation ◽  
Waterborne Diseases ◽  
Bacterial Strains ◽  
Pathogen Control ◽  
Bacteria Resistance

Abstract Waterborne diseases significantly affect human health and are responsible for high mortality rates worldwide. Antibiotics have been known for decades for treatment of bacterial strains and their overuse and irrational applications are causing increasing bacteria resistance. Therefore, there is a strong need to find alternative ways for efficient water disinfection and microbial control. Carbon nanotubes (CNTs) have demonstrated strong antimicrobial properties due to their remarkable structure. This paper reviews the antimicrobial properties of CNTs, discusses diverse mechanisms of action against microorganisms as well as their applicability for water disinfection and microbial control. Safety concerns, challenges of CNTs as antimicrobial agents and future opportunities for their application in the water remediation process are also highlighted.

Experimental and Numerical Studies on Highly Loaded Supersonic Axial Turbine Cascades

2010 ◽  
Author(s):  
T. Wolf ◽  
F. Kost ◽  
E. Janke ◽  
F. Haselbach ◽  
L. Willer
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Attractive Alternative ◽  
High Pressure Turbine ◽  
Number Range ◽  
Potential Benefits ◽  
High Mach ◽  
Aero Engines ◽  
Turbine Airfoils ◽  
Highly Loaded

For the small to medium thrust range of modern aero engines, highly loaded single stage HP turbines facilitate an attractive alternative to a more conventional 2-stage HPT architecture. Whereas the potential benefits of reductions in component length and part count, hence, in weight and cost do motivate their application, the related risks are in maintaining associated losses of supersonic flows at low values as well as managing the interaction losses between HPT and the downstream sub-component to arrive at competitive levels of component efficiencies. This paper focuses on fundamental aerodynamic concept studies and related cascade experiments in support of a future highly loaded high-pressure turbine architecture. Starting with some general remarks on low-loss supersonic aerodynamic concepts for high-pressure turbines, results from development efforts towards 2D airfoil concepts viable for high-pressure turbine airfoils are shown. In particular, CFD based design approaches are compared against experimental data taken at DLR Go¨ttingen in un-cooled cascade tests and at engine representative levels of Mach and Reynolds numbers. For the airfoils investigated, it turns out that there is indeed a supersonic Mach number range were loss levels are comparable to high Mach number subsonic values, thereby enabling a competitive aerodynamic design concept for a 3D high-pressure turbine stage.

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