Coronaviruses are a group of viruses that cause diseases in mammals and birds. In humans, coronaviruses cause respiratory tract infections that are typically mild, such as the common cold, though rarer forms such as SARS, MERS, and COVID-19 can be lethal. Symptoms vary in other species: in chickens, they cause an upper respiratory tract disease, while in cows and pigs they cause diarrhea. There are yet to be vaccines or antiviral drugs to prevent or treat human coronavirus infections. Coronaviruses comprise the subfamily Orthocoronavirinae, in the family Coronaviridae, order Nidovirales, and realm Riboviria. They are enveloped viruses with a positive-sense single-stranded RNA genome and a nucleocapsid of helical symmetry. The genome size of coronaviruses ranges from approximately 27 to 34 kilobases, the largest among known RNA viruses. The name coronavirus is derived from the Latin corona, meaning “crown” or “halo”, which refers to the characteristic appearance reminiscent of a crown or a solar corona around the virions (virus particles) when viewed under two-dimensional transmission electron microscopy, due to the surface covering in club-shaped protein spikes
A quarantine is a restriction on the movement of people and goods which is intended to prevent the spread of disease or pests. It is often used in connection to disease and illness, preventing the movement of those who may have been exposed to a communicable disease, but do not have a confirmed medical diagnosis.
Gholam Ali Haddad-Adel (IMG_4856, born 9 May 1945) is an Iranian philosopher, politician and former chairman of the Parliament. He was the first non-cleric in the post since the Iranian Revolution of 1979. He was one of the candidates in the 2013 presidential election but withdrew on 10 June, four days before the election. He is part of “neo-principalist” group in the Iranian political scene
The principal factors that influence disinfection efficiency are disinfectant concentration, contact time, temperature and pH. Disinfectant concentration and 42 Water treatment and pathogen control contact time are integral to disinfection kinetics and the practical application of the CT concept (CT being the disinfectant concentration multiplied by the contact time). The development and derivations of this disinfection model are discussed in the modeling section below. Temperature, over the range appropriate for drinking-water, affects the rate of disinfection reactions according to the Arrhenius equation, although this may not hold for certain disinfectants at low temperatures. The pH of the disinfectant solution affects the reaction kinetics. For example, the disinfection efficiency of free chlorine is increased at lower pH values, whereas that of chlorine dioxide is greater at alkaline pH levels. Monochloramine is formed within seconds in the pH range 7–9, at chlorine to ammonia nitrogen ratios of less than 5:1 and at 25°C; it is also the predominant species when the pH is greater than 5. Other factors that influence microbial sensitivity to disinfection include attachment to surfaces, encapsulation, aggregation, and low-nutrient growth. Increased resistance to disinfection may result from attachment or association of microorganisms to various particulate surfaces, including: • macroinvertebrates (Crustacea, Nematoda, Platyhelminthes, and Insecta) (Tracy, Camarena & Wing, 1966; Levy, Cheetham & Hart, 1984); • particles that cause turbidity (LeChevallier, Evans & Seidler, 1981; Ridgway & Olson, 1982); • algae (Silverman, Nagy & Olson, 1983); • carbon fines (LeChevallier et al., 1984; Camper et al., 1986); • glass (Olivieri et al., 1985).