Search This Blog

Friday, April 17, 2020

Epistemic theories of truth

From Wikipedia, the free encyclopedia
 
In philosophy, epistemic theories of truth are attempts to analyze the notion of truth in terms of epistemic notions such as knowledge, belief, acceptance, verification, justification, and perspective.

A variety of such conceptions can be classified into verificationist theories, perspectivalist or relativist theories, and pragmatic theories.

Verificationism is based on verifying propositions. The distinctive claim of verificationism is that the result of such verifications is, by definition, truth. That is, truth is reducible to this process of verification.

According to perspectivalism and relativism, a proposition is only true relative to a particular perspective. Roughly, a proposition is true relative to a perspective if and only if it is accepted, endorsed, or legitimated by that perspective.

Many authors writing on the topic of the notion of truth advocate or endorse combinations of the above positions. Each of these epistemic conceptions of truth can be subjected to various criticisms. Some criticisms apply across the board, while others are more specific.

Verificationist views

The two main kinds of verification philosophies are positivism and a-priorism.

In positivism, a proposition is meaningful, and thus capable of being true or false, if and only if it is verifiable by sensory experiences

A-priorism, often used in the domains of logic and mathematics, holds a proposition true if and only if a priori reasoning can verify it. In the related certainty theory, associated with Descartes and Spinoza, a proposition is true if and only if it is known with certainty

Logical positivism attempts to combine positivism with a version of a-priorism.

Another theory of truth which is related to a-priorism is the concept-containment theory of truth. The concept-containment theory of truth is the view that a proposition is true if and only if the concept of the predicate of the proposition is "contained in" the concept of the subject. For example, the proposition that bachelors are unmarried men is true, on this view, because the concept of the predicate (unmarried men) is contained in the concept of the subject (bachelor). A contemporary reading of the concept-containment theory of truth is to say that every true proposition is an analytically true proposition.

Perspectivist views

According to perspectivalism and relativism, a proposition is only true relative to a particular perspective. The Sophists' relativist and Nietzsche's philosophy are some of the most famous examples of such perspectivalism. There are four main versions of perspectivalism, and some interesting subdivisions:

Individual perspectivalism

According to individual perspectivalism, perspectives are the points of view of particular individual persons. So, a proposition is true for a person if and only if it is accepted or believed by that person (i.e., "true for me").

Discourse perspectivalism

According to discourse perspectivalism, a perspective is simply any system of discourse, and it is a matter of convention which one chooses. A proposition is true relative to that particular discourse if and only if it is somehow produced (or "legitimated") by the methods of that particular discourse. An example of this appears in the philosophy of mathematics: formalism. A proposition is true relative to a set of assumptions just in case it is a deductive consequence of those assumptions.

Collectivist perspectivalism

In collectivist perspectivalism, perspectives are understood as collectivities of people (cultures, traditions, etc.). There are, roughly, three versions of collectivism:

Consensus

A perspective is, roughly, the broad opinions, and perhaps norms and practices, of a community of people, perhaps all having some special feature in common. So, a proposition is true (for a community C) if, and only if, there is a consensus amongst the members of C for believing it.

Power

In the power-oriented view, a perspective is a community enforced by power, authority, military might, privilege, etc. So, a proposition is true if it "makes us powerful" or is "produced by power", thus the slogan "truth is power".

This view of truth as a political stake may be loosely associated with Martin Heidegger or with Michel Foucault's specific analysis of historical and political discourse, as well as with some social constructivists

However, the Nazi mysticism of a communitarian "blood community" conception radically differs from Heidegger or Foucault's criticism of the notion of the individual or collective subject.

Marxist

Truth-generating perspectives are collectives opposed to, or engaged in struggle against, power and authority. For example, the collective perspective of the "proletariat". So, proposition is true if it is the "product of political struggle" for the "emancipation of the workers" (Adorno). This view is again associated with some social constructivists (e.g., feminist epistemologists).

Transcendental perspectivalism

On this conception, a truth-conferring perspective is something transcendental, and outside immediate human reach. The idea is that there is a transcendental or ideal epistemic perspective and truth is, roughly, what is accepted or recognized-as-true from that ideal perspective. There are two subvarieties of transcendental perspectivalism:

Coherentism

The ideal epistemic perspective is the set of "maximally coherent and consistent propositions". A proposition is true if and only if it is a member of this maximally coherent and consistent set of propositions (associated with several German and British 19th century idealists).

Theological perspectivalism

Theologically, the ideal epistemic perspective is that of God ("God's point of view"). From this perspective, a proposition is true if and only if it agrees with the thoughts of God.

Pragmatic views

Although the pragmatic theory of truth is not strictly classifiable as an epistemic theory of truth, it does bear a relationship to theories of truth that are based on concepts of inquiry and knowledge. 

The ideal epistemic perspective is that of "completed science", which will appear in the (temporal) "limit of scientific inquiry". A proposition is true if and only if, in the long run it will come to be accepted by a group of inquirers using scientific rational inquiry. This can also be modalized: a proposition is true if, and only if, in the long run it would come to be accepted by a group of inquirers, if they were to use scientific rational inquiry. This view is thus a modification of the consensus view. The consensus need to satisfy certain constraints in order for the accepted propositions to be true. For example, the methods used must be those of scientific inquiry (criticism, observation, reproducibility, etc.). This "modification" of the consensus view is an appeal to the correspondence theory of truth, which is opposed to the consensus theory of truth. 

Long-run scientific pragmatism was defended by Charles Sanders Peirce. A variant of this viewpoint is associated with Jürgen Habermas, though he later abandoned it.

Carbon-neutral fuel

From Wikipedia, the free encyclopedia
 
Carbon-neutral fuel is energy fuel or energy systems which have no net greenhouse gas emissions or carbon footprint. One class is synthetic fuel (including methane, gasoline, diesel fuel, jet fuel or ammonia) produced from renewable, sustainable or nuclear energy used to hydrogenate carbon dioxide directly captured from the air (DAC), recycled from power plant flue exhaust gas or derived from carbonic acid in seawater. Renewable energy sources include wind turbines, solar panels, and hydroelectric powerful power stations. Another type of renewable energy source is biofuel. Such fuels are potentially carbon-neutral because they do not result in a net increase in atmospheric greenhouse gases.

To the extent that carbon-neutral fuels displace fossil fuels, or if they are produced from waste carbon or seawater carbonic acid, and their combustion is subject to carbon capture at the flue or exhaust pipe, they result in negative carbon dioxide emission and net carbon dioxide removal from the atmosphere, and thus constitute a form of greenhouse gas remediation.

Such power to gas carbon-neutral and carbon-negative fuels can be produced by the electrolysis of water to make hydrogen. Through the Sabatier reaction methane can then be produced which may then be stored to be burned later in power plants (as a synthetic natural gas), transported by pipeline, truck, or tanker ship, or be used in gas to liquids processes such as the Fischer–Tropsch process to make traditional fuels for transportation or heating.

Other carbon-negative fuels include synthetic fuels made from CO2 extracted from the atmosphere. Some companies are working on this.

Similar to regular biofuels, carbon-negative fuels only remain carbon-negative as long as the fuel is not combusted. Upon combustion, the carbon they contain (i.e. taken from industrial sources) is released again into the atmosphere (thus leveling out the environmental benefit). The time between fuel production and combustion of the fuel (the carbon storage time) can thus be quite short (far shorter than the 100 year storage time set for afforestation/reforestation projects under the Kyoto Protocol. or even underground carbon storage.

Carbon-neutral fuels are used in Germany and Iceland for distributed storage of renewable energy, minimizing problems of wind and solar intermittency, and enabling transmission of wind, water, and solar power through existing natural gas pipelines. Such renewable fuels could alleviate the costs and dependency issues of imported fossil fuels without requiring either electrification of the vehicle fleet or conversion to hydrogen or other fuels, enabling continued compatible and affordable vehicles. A 250 kilowatt synthetic methane plant has been built in Germany and it is being scaled up to 10 megawatts.

Carbon credits can also play an important role for carbon-negative fuels.

Production

Carbon-neutral fuels are synthetic hydrocarbons. They can be produced in chemical reactions between carbon dioxide, which can be captured from power plants or the air, and hydrogen, which is created by the electrolysis of water using renewable energy. The fuel, often referred to as electrofuel, stores the energy that was used in the production of the hydrogen. Coal can also be used to produce the hydrogen, but that would not be a carbon-neutral source. Carbon dioxide can be captured and buried, making fossil fuels carbon-neutral, although not renewable. Carbon capture from exhaust gas can make carbon-neutral fuels carbon negative. Other hydrocarbons can be broken down to produce hydrogen and carbon dioxide which could then be stored while the hydrogen is used for energy or fuel, which would also be carbon-neutral.

The most energy-efficient fuel to produce is hydrogen gas, which can be used in hydrogen fuel cell vehicles, and which requires the fewest process steps to produce. 

There are a few more fuels that can be created using hydrogen. Formic acid for example can be made by reacting the hydrogen with CO2. Formic acid combined with CO2 can form isobutanol.

Methanol can be made from a chemical reaction of a carbon-dioxide molecule with three hydrogen molecules to produce methanol and water. The stored energy can be recovered by burning the methanol in a combustion engine, releasing carbon dioxide, water, and heat. Methane can be produced in a similar reaction. Special precautions against methane leaks are important since methane is nearly 100 times as potent as CO2, in terms of Global warming potential. More energy can be used to combine methanol or methane into larger hydrocarbon fuel molecules.

Researchers have also suggested using methanol to produce dimethyl ether. This fuel could be used as a substitute for diesel fuel due to its ability to self ignite under high pressure and temperature. It is already being used in some areas for heating and energy generation. It is nontoxic, but must be stored under pressure. Larger hydrocarbons and ethanol can also be produced from carbon dioxide and hydrogen. 

All synthetic hydrocarbons are generally produced at temperatures of 200–300 °C, and at pressures of 20 to 50 bar. Catalysts are usually used to improve the efficiency of the reaction and create the desired type of hydrocarbon fuel. Such reactions are exothermic and use about 3 mol of hydrogen per mole of carbon dioxide involved. They also produce large amounts of water as a byproduct.

Sources of carbon for recycling

The most economical source of carbon for recycling into fuel is flue-gas emissions from fossil-fuel combustion where it can be obtained for about US$7.50 per ton. However, this is not carbon-neutral, since the carbon is of fossil origin, therefore moving carbon from the geosphere to the atmosphere. Automobile exhaust gas capture has also been seen as economical but would require extensive design changes or retrofitting. Since carbonic acid in seawater is in chemical equilibrium with atmospheric carbon dioxide, extraction of carbon from seawater has been studied. Researchers have estimated that carbon extraction from seawater would cost about $50 per ton. Carbon capture from ambient air is more costly, at between $94 and $232 per ton and is considered impractical for fuel synthesis or carbon sequestration. Direct air capture is less developed than other methods. Proposals for this method involve using a caustic chemical to react with carbon dioxide in the air to produce carbonates. These can then be broken down and hydrated to release pure CO2 gas and regenerate the caustic chemical. This process requires more energy than other methods because carbon dioxide is at much lower concentrations in the atmosphere than in other sources.

Researchers have also suggested using biomass as a carbon source for fuel production. Adding hydrogen to the biomass would reduce its carbon to produce fuel. This method has the advantage of using plant matter to cheaply capture carbon dioxide. The plants also add some chemical energy to the fuel from biological molecules. This may be a more efficient use of biomass than conventional biofuel because it uses most of the carbon and chemical energy from the biomass instead of releasing as much energy and carbon. Its main disadvantage is, as with conventional ethanol production, it competes with food production.

Renewable and nuclear energy costs

Nighttime wind power is considered the most economical form of electrical power with which to synthesize fuel, because the load curve for electricity peaks sharply during the warmest hours of the day, but wind tends to blow slightly more at night than during the day. Therefore, the price of nighttime wind power is often much less expensive than any alternative. Off-peak wind power prices in high wind penetration areas of the U.S. averaged 1.64 cents per kilowatt-hour in 2009, but only 0.71 cents/kWh during the least expensive six hours of the day. Typically, wholesale electricity costs 2 to 5 cents/kWh during the day. Commercial fuel synthesis companies suggest they can produce gasoline for less than petroleum fuels when oil costs more than $55 per barrel.

In 2010, a team of process chemists led by Heather Willauer of the U.S. Navy, estimates that 100 megawatts of electricity can produce 160 cubic metres (41,000 US gal) of jet fuel per day and shipboard production from nuclear power would cost about $1,600 per cubic metre ($6/US gal). While that was about twice the petroleum fuel cost in 2010, it is expected to be much less than the market price in less than five years if recent trends continue. Moreover, since the delivery of fuel to a carrier battle group costs about $2,100 per cubic metre ($8/US gal), shipboard production is already much less expensive.

Willauer said seawater is the "best option" for a source of synthetic jet fuel. By April 2014, Willauer's team had not yet made fuel to the standard required by military jets, but they were able in September 2013 to use the fuel to fly a radio-controlled model airplane powered by a common two-stroke internal combustion engine. Because the process requires a large input of electrical energy, a plausible first step of implementation would be for American nuclear-powered aircraft carriers (the Nimitz-class and the Gerald R. Ford-class) to manufacture their own jet fuel. The U.S. Navy is expected to deploy the technology some time in the 2020s.

Demonstration projects and commercial development

A 250 kilowatt methane synthesis plant was constructed by the Center for Solar Energy and Hydrogen Research (ZSW) at Baden-Württemberg and the Fraunhofer Society in Germany and began operating in 2010. It is being upgraded to 10 megawatts, scheduled for completion in autumn, 2012.

The George Olah carbon dioxide recycling plant operated by Carbon Recycling International in Grindavík, Iceland has been producing 2 million liters of methanol transportation fuel per year from flue exhaust of the Svartsengi Power Station since 2011. It has the capacity to produce 5 million liters per year.

Audi has constructed a carbon-neutral liquefied natural gas (LNG) plant in Werlte, Germany. The plant is intended to produce transportation fuel to offset LNG used in their A3 Sportback g-tron automobiles, and can keep 2,800 metric tons of CO2 out of the environment per year at its initial capacity.

Commercial developments are taking place in Columbia, South Carolina, Camarillo, California, and Darlington, England. A demonstration project in Berkeley, California proposes synthesizing both fuels and food oils from recovered flue gases.

Greenhouse gas remediation

Carbon-neutral fuels can lead to greenhouse gas remediation because carbon dioxide gas would be reused to produce fuel instead of being released into the atmosphere. Capturing the carbon dioxide in flue gas emissions from power plants would eliminate their greenhouse gas emissions, although burning the fuel in vehicles would release that carbon because there is no economical way to capture those emissions. This approach would reduce net carbon dioxide emission by about 50% if it were used on all fossil fuel power plants. Most coal and natural gas power plants have been predicted to be economically retrofittable with carbon dioxide scrubbers for carbon capture to recycle flue exhaust or for carbon sequestration. Such recycling is expected to not only cost less than the excess economic impacts of climate change if it were not done, but also to pay for itself as global fuel demand growth and peak oil shortages increase the price of petroleum and fungible natural gas.

Capturing CO2 directly from the air or extracting carbonic acid from seawater would also reduce the amount of carbon dioxide in the environment, and create a closed cycle of carbon to eliminate new carbon dioxide emissions. Use of these methods would eliminate the need for fossil fuels entirely, assuming that enough renewable energy could be generated to produce the fuel. Using synthetic hydrocarbons to produce synthetic materials such as plastics could result in permanent sequestration of carbon from the atmosphere.

Technologies

Traditional fuels, methanol or ethanol

Some authorities have recommended producing methanol instead of traditional transportation fuels. It is a liquid at normal temperatures and can be toxic if ingested. Methanol has a higher octane rating than gasoline but a lower energy density, and can be mixed with other fuels or used on its own. It may also be used in the production of more complex hydrocarbons and polymers. Direct methanol fuel cells have been developed by Caltech's Jet Propulsion Laboratory to convert methanol and oxygen into electricity. It is possible to convert methanol into gasoline, jet fuel or other hydrocarbons, but that requires additional energy and more complex production facilities. Methanol is slightly more corrosive than traditional fuels, requiring automobile modifications on the order of US$100 each to use it.

In 2016, a method using carbon spikes, copper nanoparticles and nitrogen that converts carbon dioxide to ethanol was developed.

Microalgae

Microalgae is a potential carbon neutral fuel, but efforts to turn it into one have been unsuccessful so far. Microalgae are aquatic organisms living in a large and diverse group. They are unicellular organisms that do not have complex cell structures like plants. However, they are still photo autotrophic, able to use solar energy to convert chemical forms via photosynthesis. They are typically found in freshwater and marine system and there are approximately 50,000 species that has been found.

Microalgae will be a huge substitute for the needs of fuel in the era of global warming. Growing microalgae is important in supporting the global movement of reducing global CO2 emissions. Microalgae has a better ability, compared to conventional biofuel crops, in acting as a CO2fixation source as they convert CO2 into biomass via photosynthesis at higher rates. Microalgae is a better CO2 converter than conventional biofuel crops. 
 
With that being said, a considerable interest to cultivate microalgae has been increasing in the past several years. Microalgae is seen as a potential feedstock for biofuel production as their ability to produce polysaccharides and triglycerides (sugars and fats) which are both raw materials for bioethanol and biodiesel fuel. Microalgae also can be used as a livestock feed due to their proteins. Even more, some species of microalgae produce valuable compounds such as pigments and pharmaceuticals.

Production

Two main ways of cultivating microalgae are raceway pond systems and photo-bioreactors. Raceway pond systems are constructed by a closed loop oval channel that has a paddle wheel to circulate water and prevent sedimentation. The channel is open to the air and its depth is in the range of 0.25–0.4 m (0.82–1.31 ft). The pond needs to be kept shallow since self-shading and optical absorption can cause the limitation of light penetration through the solution of algae broth. PBRs's culture medium is constructed by closed transparent array of tubes. It has a central reservoir which circulated the microalgae broth. PBRs is an easier system to be controlled compare to the raceway pond system, yet it costs a larger overall production expenses.

The carbon emissions from microalgae biomass produced in raceway ponds could be compared to the emissions from conventional biodiesel by having inputs of energy and nutrients as carbon intensive. The corresponding emissions from microalgae biomass produced in PBRs could also be compared and might even exceed the emissions from conventional fossil diesel. The inefficiency is due to the amount of electricity used to pump the algae broth around the system. Using co-product to generate electricity is one strategy that might improve the overall carbon balance. Another thing that needs to be acknowledged is that environmental impacts can also come from water management, carbon dioxide handling, and nutrient supply, several aspects that could constrain system design and implementation options. But, in general, Raceway Pond systems demonstrate a more attractive energy balance than PBR systems.

Economy

Production cost of microalgae-biofuel through implementation of raceway pond systems is dominated by the operational cost which includes labour, raw materials, and utilities. In raceway pond system, during the cultivation process, electricity takes up the largest energy fraction of total operational energy requirements. It is used to circulate the microalgae cultures. It takes up an energy fraction ranging from 22% to 79%. In contrast, capital cost dominates the cost of production of microalgae-biofuel in PBRs. This system has a high installation cost though the operational cost is relatively lower than raceway pond systems.

Microalgae-biofuel production costs a larger amount of money compared to fossil fuel production. The cost estimation of producing microalgae-biofuel is around $3.1 per litre ($11.57/US gal). Meanwhile, data provided by California Energy Commission shows that fossil fuel production in California costs $0.48 per litre ($1.820/US gal) by October, 2018. This price ratio leads many to choose fossil fuel for economic reasons, even as this results in increased emissions of carbon dioxide and other greenhouse gases. Advancement in renewable energy is being developed to reduce this production cost.

Environmental impact

There are several known environmental impacts of cultivating microalgae:
Water resource
There could be an increasing demand of fresh water as microalgaes are aquatic organisms. Fresh water is used to compensate evaporation in raceway pond systems. It is used for cooling purpose. Using recirculating water might compensate for the needs of the water but it comes with a greater risk of infection and inhibition: bacteria, fungi, viruses. These inhibitors are found in greater concentrations in recycled waters along with non-living inhibitors such as organic and inorganic chemicals and remaining metabolites from destroyed microalgae cells.
Algae toxicity
Many microalgae species could produce some toxins (ranging from ammonia to physiologically active polypeptides and polysaccharides) in some point in their life cycle. These algae toxins may be important and valuable products in their applications in biomedical, toxicological and chemical research. However, they also come with negative effects. These toxins can be either acute or chronic. The acute example is the paralytic shellfish poisoning that may cause death. One of the chronic one is the carcinogenic and ulcerative tissue slow changes caused by carrageenan toxins produced in red tides. Since the high variability of toxins producing microalgae species, the presence or absence of toxins in a pond will not always be able to be predicted. It all depends on the environment and ecosystem condition.

Diesel from water and carbon dioxide

Audi has co-developed E-diesel, a carbon-neutral fuel with a high cetane number. It is also working on E-benzin, which is created using a similar process.

Production

Water undergoes electrolysis at high temperatures to form Hydrogen gas and Oxygen gas. The energy to perform this is extracted from renewable sources such as wind power. Then, the hydrogen is reacted with compressed carbon dioxide captured by direct air capture. The reaction produces blue crude which consists of hydrocarbon. The blue crude is then refined to produce high efficiency E-diesel. This method is, however, still debatable because with the current production capability it can only produce 3,000 liters in a few months, 0.0002% of the daily production of fuel in the US. Furthermore, the thermodynamic and economic feasibility of this technology have been questioned. An article suggests that this technology does not create an alternative to fossil fuel but rather converting renewable energy into liquid fuel. The article also states that the energy return on energy invested using fossil diesel is 18 times higher than that for e-diesel.

History

Investigation of carbon-neutral fuels has been ongoing for decades. A 1965 report suggested synthesizing methanol from carbon dioxide in air using nuclear power for a mobile fuel depot. Shipboard production of synthetic fuel using nuclear power was studied in 1977 and 1995. A 1984 report studied the recovery of carbon dioxide from fossil fuel plants. A 1995 report compared converting vehicle fleets for the use of carbon-neutral methanol with the further synthesis of gasoline.

Solar combisystem

From Wikipedia, the free encyclopedia
 
A solar combisystem provides both solar space heating and cooling as well as hot water from a common array of solar thermal collectors, usually backed up by an auxiliary non-solar heat source.
Solar combisystems may range in size from those installed in individual properties to those serving several in a block heating scheme. Those serving larger groups of properties district heating tend to be called central solar heating schemes.

Many types of solar combisystems are produced - over 20 were identified in the first international survey, conducted as part of IEA SHC Task 14  in 1997. The systems on the market in a particular country may be more restricted, however, as different systems have tended to evolve in different countries. Prior to the 1990s such systems tended to be custom-built for each property. Since then commercialised packages have developed and are now generally used.

Depending on the size of the combisystem installed, the annual space heating contribution can range from 10% to 60% or more in ultra-low energy Passivhaus-type buildings; even up to 100% where a large interseasonal thermal store or concentrating solar thermal heat is used. The remaining heat requirement is supplied by one or more auxiliary sources in order to maintain the heat supply once the solar heated water is exhausted. Such auxiliary heat sources may also use other renewable energy sources (when a geothermal heat pump is used, the combisystem is called geosolar) and, sometimes, rechargeable batteries.

During 2001, around 50% of all the domestic solar collectors installed in Austria, Switzerland, Denmark, and Norway were to supply combisystems, while in Sweden it was greater. In Germany, where the total collector area installed (900,000 m2) was much larger than in the other countries, 25% was for combisystem installations. Combisystems have also been installed in Canada since the mid-1980s.

Some combisystems can incorporate solar thermal cooling in summer.

Classification

Following the work of IEA SHC Task 26 (1998 to 2002), solar combisystems can be classified according to two main aspects; firstly by the heat (or cool) storage category (the way in which water is added to and drawn from the storage tank and its effect on stratification); secondly by the auxiliary heat (or cool) management category (the way in which non-solar-thermal auxiliary heaters or coolers can be integrated into the system). 

Maintaining stratification (the variation in water temperature from cooler at the foot of a tank to warmer at the top) is important so that the combisystem can supply hot or cool water and space heating and cooling water at different temperatures. 

Heat and cool storage categories
Category Description
A No controlled storage device for space heating and cooling.
B Heat and cool management and stratification enhancement by means of multiple tanks and/or by multiple inlet/outlet pipes and/or by three- or four-way valves to control flow through the inlet/outlet pipes.
C Heat and cool management using natural convection in storage tanks and/or between them to maintain stratification to a certain extent.
D Heat and cool management using natural convection in storage tanks and built-in stratification devices.
B/D Heat and cool management by natural convection in storage tanks and built-in stratifiers as well as multiple tanks and/or multiple inlet/outlet pipes and/or three- or four-way valves to control flow through the inlet/outlet pipes.
 
Auxiliary heat and cool management categories
Category Description
M (mixed mode) The space heating loop is fed from a single store heated by both solar collectors and the auxiliary heater.
P (parallel mode) The space heating and cooling loop is fed alternatively by the solar collectors (or a solar water storage tank), or by the auxiliary heater or cooler; or there is no hydraulic connection between the solar heat and cool distribution and the auxiliary heat emissions.
S (serial mode) The space heating and cooling loop may be fed by the auxiliary heater, or by both the solar collectors (or a solar water storage tank) and the auxiliary heater connected in series on the return line of the space heating loop.

A solar combisystem may therefore be described as being of type B/DS, CS, etc. 

Within these types, systems may be configured in many different ways. For the individual house they may – or may not – have the storage tanks, controls and auxiliary heater and cooler integrated into a single prefabricated package. In contrast, there are also large centralised systems serving a number of properties.

The simplest combisystems – the Type A – have no "controlled storage device". Instead they pump warm (or cool) water from the solar collectors through underfloor central heating pipes embedded in the concrete floor slab. The floor slab is thickened to provide thermal mass and so that the heat and cool from the pipes (at the bottom of the slab) is released during the evening.

Combisystem design

The size and complexity of combisystems, and the number of options available, mean that comparing design alternatives is not straightforward. Useful approximations of performance can be produced relatively easily, however accurate predictions remain difficult. 

Tools for designing solar combisystems are available, varying from manufacturer's guidelines to nomograms (such as the one developed for IEA SHC Task 26) to various computer simulation software of varying complexity and accuracy.

Among the software and packages are CombiSun (released free by the Task 26 team, which can be used for basic system sizing) and the free SHWwin (Austria, in German). Other commercial systems are available. 

Solar combisystems generally use underfloor heating and cooling.

Concentrating solar thermal technology may be used to make the collectors as small as possible.

Technologies

Solar combisystems use similar technologies to those used for solar hot water and for regular central heating and underfloor heating, as well as those used in the auxiliary systems - microgeneration technologies or otherwise.

The element unique to combisystems is the way that these technologies are combined, and the control systems used to integrate them, plus any stratifier technology that might be employed.

Relationship to low energy building

By the end of the 20th century solar hot water systems had been capable of meeting a significant portion of domestic hot water requirements in many climate zones. However it was only with the development of reliable low-energy building techniques in the last decades of the century that extending such systems for space heating became realistic in temperate and colder climatic zones.

As heat demand reduces, the overall size and cost of the system is reduced, and the lower water temperatures typical of solar heating may be more readily used - especially when coupled with underfloor heating or wall heating. The volume occupied by the equipment also reduces, which also increases the flexibility of its location.

In common with other heating systems in low-energy buildings, system performance is more sensitive to the number of occupants, room temperature and ventilation rates, when compared to regular buildings where such effects are small in relation to the higher overall energy demand.

Seasonal thermal energy storage

From Wikipedia, the free encyclopedia
 
Seasonal thermal energy storage (or STES) is the storage of heat or cold for periods of up to several months. The thermal energy can be collected whenever it is available and be used whenever needed, such as in the opposing season. For example, heat from solar collectors or waste heat from air conditioning equipment can be gathered in hot months for space heating use when needed, including during winter months. Waste heat from industrial process can similarly be stored and be used much later. Or the natural cold of winter air can be stored for summertime air conditioning. STES stores can serve district heating systems, as well as single buildings or complexes. Among seasonal storages used for heating, the design peak annual temperatures generally are in the range of 27 to 80 °C (81 to 180 °F), and the temperature difference occurring in the storage over the course of a year can be several tens of degrees. Some systems use a heat pump to help charge and discharge the storage during part or all of the cycle. For cooling applications, often only circulation pumps are used. A less common term for STES technologies is interseasonal thermal energy storage.

Examples for district heating include Drake Landing Solar Community where ground storage provides 97% of yearly consumption without heat pumps, and Danish pond storage with boosting.

STES technologies

There are several types of STES technology, covering a range of applications from single small buildings to community district heating networks. Generally, efficiency increases and the specific construction cost decreases with size.

Underground thermal energy storage

  • UTES (underground thermal energy storage), in which the storage medium may be geological strata ranging from earth or sand to solid bedrock, or aquifers. UTES technologies include:
    • ATES (aquifer thermal energy storage). An ATES store is composed of a doublet, totaling two or more wells into a deep aquifer that is contained between impermeable geological layers above and below. One half of the doublet is for water extraction and the other half for reinjection, so the aquifer is kept in hydrological balance, with no net extraction. The heat (or cold) storage medium is the water and the substrate it occupies. Germany’s Reichstag building has been both heated and cooled since 1999 with ATES stores, in two aquifers at different depths.
In the Netherlands there are well over 1,000 ATES systems, which are now a standard construction option. A significant system has been operating at Richard Stockton College (New Jersey) for several years. ATES has a lower installation cost than BTES because usually fewer holes are drilled, but ATES has a higher operating cost. Also, ATES requires particular underground conditions to be feasible, including the presence of an aquifer.
    • BTES (borehole thermal energy storage). BTES stores can be constructed wherever boreholes can be drilled, and are composed of one to hundreds of vertical boreholes, typically 155 mm (6.102 in) in diameter. Systems of all sizes have been built, including many quite large.
The strata can be anything from sand to crystalline hardrock, and depending on engineering factors the depth can be from 50 to 300 metres (164 to 984 ft). Spacings have ranged from 3 to 8 metres (9.8 to 26.2 ft). Thermal models can be used to predict seasonal temperature variation in the ground, including the establishment of a stable temperature regime which is achieved by matching the inputs and outputs of heat over one or more annual cycles. Warm-temperature seasonal heat stores can be created using borehole fields to store surplus heat captured in summer to actively raise the temperature of large thermal banks of soil so that heat can be extracted more easily (and more cheaply) in winter. Interseasonal Heat Transfer uses water circulating in pipes embedded in asphalt solar collectors to transfer heat to Thermal Banks created in borehole fields. A ground source heat pump is used in winter to extract the warmth from the Thermal Bank to provide space heating via underfloor heating. A high Coefficient of Performance is obtained because the heat pump starts with a warm temperature of 25 °C (77 °F) from the thermal store, instead of a cold temperature of 10 °C (50 °F) from the ground. A BTES operating at Richard Stockton College since 1995 at a peak of about 29 °C (84.2 °F) consists of 400 boreholes 130 metres (427 ft) deep under a 3.5-acre (1.4 ha) parking lot. It has a heat loss of 2% over six months. The upper temperature limit for a BTES store is 85 °C (185 °F) due to characteristics of the PEX pipe used for BHEs, but most do not approach that limit. Boreholes can be either grout- or water-filled depending on geological conditions, and usually have a life expectancy in excess of 100 years. Both a BTES and its associated district heating system can be expanded incrementally after operation begins, as at Neckarsulm, Germany. BTES stores generally do not impair use of the land, and can exist under buildings, agricultural fields and parking lots. An example of one of the several kinds of STES illustrates well the capability of interseasonal heat storage. In Alberta, Canada, the homes of the Drake Landing Solar Community (in operation since 2007), get 97% of their year-round heat from a district heat system that is supplied by solar heat from solar-thermal panels on garage roofs. This feat – a world record – is enabled by interseasonal heat storage in a large mass of native rock that is under a central park. The thermal exchange occurs via a cluster of 144 boreholes, drilled 37 metres (121 ft) into the earth. Each borehole is 155 mm (6.1 in) in diameter and contains a simple heat exchanger made of small diameter plastic pipe, through which water is circulated. No heat pumps are involved.
    • CTES (cavern or mine thermal energy storage). STES stores are possible in flooded mines, purpose-built chambers, or abandoned underground oil stores (e.g. those mined into crystalline hardrock in Norway), if they are close enough to a heat (or cold) source and market.
    • Energy Pilings. During construction of large buildings, BHE heat exchangers much like those used for BTES stores have been spiraled inside the cages of reinforcement bars for pilings, with concrete then poured in place. The pilings and surrounding strata then become the storage medium.
    • GIITS (geo interseasonal insulated thermal storage). During construction of any building with a primary slab floor, an area approximately the footprint of the building to be heated, and > 1 m in depth, is insulated on all 6 sides typically with HDPE closed cell insulation. Pipes are used to transfer solar energy into the insulated area, as well as extracting heat as required on demand. If there is significant internal ground water flow, remedial actions are needed to prevent it.

Surface and above ground technologies

  • Pit Storage. Lined, shallow dug pits that are filled with gravel and water as the storage medium are used for STES in many Danish district heating systems. Storage pits are covered with a layer of insulation and then soil, and are used for agriculture or other purposes. A system in Marstal, Denmark, includes a pit storage supplied with heat from a field of solar-thermal panels. It is initially providing 20% of the year-round heat for the village and is being expanded to provide twice that. The world's largest pit store (200,000 m3 (7,000,000 cu ft)) was commissioned in Vojens, Denmark, in 2015, and allows solar heat to provide 50% of the annual energy for the world's largest solar-enabled district heating system.
  • Large-scale thermal storage with water. Large scale STES water storage tanks can be built above ground, insulated, and then covered with soil.
  • Horizontal heat exchangers. For small installations, a heat exchanger of corrugated plastic pipe can be shallow-buried in a trench to create a STES.
  • Earth-bermed buildings. Stores heat passively in surrounding soil.
  • Salt hydrate technology This technology achieves significantly higher storage densities than water-based heat storage.

Conferences and organizations

The International Energy Agency's Energy Conservation through Energy Storage (ECES) Programme has held triennial global energy conferences since 1981. The conferences originally focused exclusively on STES, but now that those technologies are mature other topics such as phase change materials (PCM) and electrical energy storage are also being covered. Since 1985 each conference has had "stock" (for storage) at the end of its name; e.g. EcoStock, ThermaStock. They are held at various locations around the world. Most recent were InnoStock 2012 (the 12th International Conference on Thermal Energy Storage) in Lleida, Spain and GreenStock 2015 in Beijing. EnerStock 2018 will be held in Adana, Turkey in April 2018.

The IEA-ECES programme continues the work of the earlier International Council for Thermal Energy Storage which from 1978 to 1990 had a quarterly newsletter and was initially sponsored by the U.S. Department of Energy. The newsletter was initially called ATES Newsletter, and after BTES became a feasible technology it was changed to STES Newsletter.

Use of STES for small, passively heated buildings

Small passively heated buildings typically use the soil adjoining the building as a low-temperature seasonal heat store that in the annual cycle reaches a maximum temperature similar to average annual air temperature, with the temperature drawn down for heating in colder months. Such systems are a feature of building design, as some simple but significant differences from 'traditional' buildings are necessary. At a depth of about 20 feet (6 m) in the soil, the temperature is naturally stable within a year-round range, if the draw down does not exceed the natural capacity for solar restoration of heat. Such storage systems operate within a narrow range of storage temperatures over the course of a year, as opposed to the other STES systems described above for which large annual temperature differences are intended.

Two basic passive solar building technologies were developed in the US during the 1970s and 1980s. They utilize direct heat conduction to and from thermally isolated, moisture-protected soil as a seasonal storage medium for space heating, with direct conduction as the heat return method. In one method, "passive annual heat storage" (PAHS), the building’s windows and other exterior surfaces capture solar heat which is transferred by conduction through the floors, walls, and sometimes the roof, into adjoining thermally buffered soil.

When the interior spaces are cooler than the storage medium, heat is conducted back to the living space. The other method, “annualized geothermal solar” (AGS) uses a separate solar collector to capture heat. The collected heat is delivered to a storage device (soil, gravel bed or water tank) either passively by the convection of the heat transfer medium (e.g. air or water) or actively by pumping it. This method is usually implemented with a capacity designed for six months of heating. 

A number of examples of the use of solar thermal storage from across the world include: Suffolk One a college in East Anglia, England, that uses a thermal collector of pipe buried in the bus turning area to collect solar energy that is then stored in 18 boreholes each 100 metres (330 ft) deep for use in winter heating. Drake Landing Solar Community in Canada uses solar thermal collectors on the garage roofs of 52 homes, which is then stored in an array of 35 metres (115 ft) deep boreholes. The ground can reach temperatures in excess of 70 °C which is then used to heat the houses passively. The scheme has been running successfully since 2007. In Brædstrup, Denmark, some 8,000 square metres (86,000 sq ft) of solar thermal collectors are used to collect some 4,000,000 kWh/year similarly stored in an array of 50 metres (160 ft) deep boreholes.

Liquid engineering

Architect Matyas Gutai obtained an EU grant to construct a house in Hungary which uses extensive water filled wall panels as heat collectors and reservoirs with underground heat storage water tanks. The design uses microprocessor control.

Small buildings with internal STES water tanks

A number of homes and small apartment buildings have demonstrated combining a large internal water tank for heat storage with roof-mounted solar-thermal collectors. Storage temperatures of 90 °C (194 °F) are sufficient to supply both domestic hot water and space heating. The first such house was MIT Solar House #1, in 1939. An eight-unit apartment building in Oberburg, Switzerland was built in 1989, with three tanks storing a total of 118 m3 (4,167 cubic feet) that store more heat than the building requires. Since 2011, that design is now being replicated in new buildings.

In Berlin, the “Zero Heating Energy House”, was built in 1997 in as part of the IEA Task 13 low energy housing demonstration project. It stores water at temperatures up to 90 °C (194 °F) inside a 20 m3 (706 cubic feet) tank in the basement.

A similar example was built in Ireland in 2009, as a prototype. The solar seasonal store consists of a 23 m3 (812 cu ft) tank, filled with water, which was installed in the ground, heavily insulated all around, to store heat from evacuated solar tubes during the year. The system was installed as an experiment to heat the world's first standardized pre-fabricated passive house in Galway, Ireland. The aim was to find out if this heat would be sufficient to eliminate the need for any electricity in the already highly efficient home during the winter months.

Use of STES in greenhouses

STES is also used extensively for the heating of greenhouses. ATES is the kind of storage commonly in use for this application. In summer, the greenhouse is cooled with ground water, pumped from the “cold well” in the aquifer. The water is heated in the process, and is returned to the “warm well” in the aquifer. When the greenhouse needs heat, such as to extend the growing season, water is withdrawn from the warm well, becomes chilled while serving its heating function, and is returned to the cold well. This is a very efficient system of free cooling, which uses only circulation pumps and no heat pumps.

Influenza treatment

From Wikipedia, the free encyclopedia
 
Treatments for influenza include a range of medications and therapies that are used in response to disease influenza. Treatments may either directly target the influenza virus itself; or instead they may just offer relief to symptoms of the disease, while the body's own immune system works to recover from infection.

The two main classes of antiviral drugs used against influenza are neuraminidase inhibitors, such as zanamivir and oseltamivir, or inhibitors of the viral M2 protein, such as amantadine and rimantadine. These drugs can reduce the severity of symptoms if taken soon after infection and can also be taken to decrease the risk of infection. However, virus strains have emerged that show drug resistance to both classes of drug.

Symptomatic treatment

The United States authority on disease prevention, the Centers for Disease Control and Prevention (CDC), recommends that persons suffering from influenza infections:
  • Stay at home
  • Get plenty of rest
  • Drink a lot of liquids
  • Do not smoke or drink alcohol
  • Consider over-the-counter medications to relieve flu symptoms
  • Consult a physician early on for best possible treatment
  • Remain alert for emergency warning signs
Warning signs are symptoms that indicate that the disease is becoming serious and needs immediate medical attention. These include:
  • Difficulty breathing or shortness of breath
  • Pain or pressure in the chest or abdomen
  • Dizziness
  • Confusion
  • Severe or persistent vomiting
In children other warning signs include irritability, failing to wake up and interact, rapid breathing, and a blueish skin color. Another warning sign in children is if the flu symptoms appear to resolve, but then reappear with fever and a bad cough.

Antiviral drugs

Antiviral drugs directly target the viruses responsible for influenza infections. Generally, anti-viral drugs work optimally when taken within a few days of the onset of symptoms. Certain drugs are used prophylactically, that is they are used in uninfected individuals to guard against infection. 

Four licensed influenza antiviral agents are available in the United States: amantadine, rimantadine, zanamivir, and oseltamivir. They are available through prescription only. These drugs fall into categories as either M2-inhibitors (admantane derivatives) or neuraminidase inhibitors as illustrated in the following table.
Antiviral drugs to treat influenza
Class Effective Against Drug Name (INN) Brand Name Year Approved Manufacturer
M2 inhibitors
(adamantane derivatives)
Influenza A Amantadine Symmetrel 1976 Endo Pharmaceuticals
Rimantadine Flumadine 1994 Forest Laboratories
Neuraminidase inhibitors Influenza A & B Zanamivir Relenza 1999 GlaxoSmithKline
Oseltamivir Tamiflu 1999 Hoffmann-La Roche
Cap-dependent endonuclease inhibitor Influenza A & B Baloxavir marboxil Xofluza 2018 Shionogi & CompanyRoche AG
Note: Neuraminidase inhibitors are approved for prophylaxis use in children and adults.

In Russia and China a drug called arbidol is also used as a treatment. Testing of the drug has predominantly occurred in these countries and, although no clinical trials have been published demonstrating this is an effective drug, some data suggest that this could be a useful treatment for influenza.

Peramivir

Peramivir, an experimental anti-influenza drug, developed by BioCryst Pharmaceuticals has not yet been approved for sale in the United States. This drug can be given as an injection, so may be particularly useful in serious cases of influenza where the patient is unconscious and oral or inhaled drug administration is therefore difficult.

In October 2009, it was reported that the experimental antiviral drug Peramivir had been effective in treating serious cases of swine flu. On October 23, the U.S. Food and Drug Administration (FDA) issued an Emergency Use Authorization for Peramivir (now expired), leading to wider and faster availability for patients. Since the FDA's decisions and actions are closely watched around the world, this move is likely to also increase demand for Peramivir internationally.

Interferons

Interferons are cellular signalling factors produced in response to viral infection. Research into the use of interferons to combat influenza began in the 1960s in the Soviet Union, culminating in a trial of 14,000 subjects at the height of the Hong Kong Flu of 1969, in which those treated prophylactically with interferon were more than 50% less likely to suffer symptoms, though evidence of latent infection was present. In these early studies leukocytes were collected from donated blood and exposed to a high dose of Newcastle disease, causing them to release interferons. Although interferon therapies became widespread in the Soviet Union, the method was doubted in the United States after high doses of interferon proved ineffective in trials. Though the 1969 study used 256 units of interferon, subsequent studies used up to 8.4 million units. It has since been proposed that activity of interferon is highest at low concentrations. Phase III trials in Australia are planned for 2010, and initial trials are planned in the U.S. for late 2009.

Interferons have also been investigated as adjuvants to enhance to effectiveness of influenza vaccines. This work was based on experiments in mice that suggested that type I interferons could enhance the effectiveness of influenza vaccines in mice. However, a clinical trial in 2008 found that oral dosing of elderly patients with interferon-alpha actually reduced their immune response to an influenza vaccine.

Viferon is a suppository of (non-pegylated) interferon alpha-2b, ascorbic acid (vitamin C), and tocopherol (vitamin E) which was reported in two small studies to be as effective as arbidol. It is sold in Russia for $4–$9 per suppository depending on dose. Another interferon alfa-2b medicine, "Grippferon", nasal drops, is used for treatment and emergency prevention of Influenza and cold. Its manufacturers have appealed to the WHO to consider its use against avian influenza and H1N1 Influenza 09 (Human Swine Flu), stating that it was used successfully in Russia for eight years, but that "the medical profession in Europe and the USA is not informed about this medicine".

Drug resistance

Influenza viruses can show resistance to anti-viral drugs. Like the development of bacterial antibiotic resistance, this can result from over-use of these drugs. For example, a study published in the June 2009 Issue of Nature Biotechnology emphasized the urgent need for augmentation of oseltamivir (Tamiflu) stockpiles with additional antiviral drugs including zanamivir (Relenza) based on an evaluation of the performance of these drugs in the scenario that the 2009 H1N1 'Swine Flu' neuraminidase (NA) were to acquire the tamiflu-resistance (His274Tyr) mutation which is currently widespread in seasonal H1N1 strains. Yet another example is in the case of the amantadines treatment may lead to the rapid production of resistant viruses, and over-use of these drugs has probably contributed to the spread of resistance. In particular, this high-level of resistance may be due to the easy availability of amantadines as part of over-the-counter cold remedies in countries such as China and Russia, and their use to prevent outbreaks of influenza in farmed poultry.

On the other hand, a few strains resistant to neuraminidase inhibitors have emerged and circulated in the absence of much use of the drugs involved, and the frequency with which drug resistant strains appears shows little correlation with the level of use of these drugs. However, laboratory studies have shown that it is possible for the use of sub-optimal doses of these drugs as a prophylactic measure might contribute to the development of drug resistance.

During the United States 2005–2006 influenza season, increasing incidence of drug resistance by strain H3N2 to amantadine and rimantadine led the CDC to recommend oseltamivir as a prophylactic drug, and the use of either oseltamivir or zanamivir as treatment.

Over-the-counter medication

Antiviral drugs are prescription-only medication in the United States. Readily available over-the-counter medications do not directly affect the disease, but they do provide relief from influenza symptoms, as illustrated in the table below. 

OTC medicines provide relief for 'flu symptoms
Symptom(s) OTC Medicine
fever, aches, pains, sinus pressure, sore throat analgesics
nasal congestion, sinus pressure decongestants
sinus pressure, runny nose, watery eyes, cough antihistamines
cough cough suppressant
sore throat local anesthetics

Children and teenagers with flu symptoms (particularly fever) should avoid taking aspirin as taking aspirin in the presence of influenza infection (especially Influenzavirus B) can lead to Reye's syndrome, a rare but potentially fatal disease of the brain.

Off-label uses of other drugs

Several generic prescription medications might prove useful to treat a potential H5N1 avian flu outbreak, including statins, fibrates, and chloroquine.

Nutritional supplements and herbal medicines

Malnutrition can reduce the ability of the body to resist infections and is a common cause of immunodeficiency in the developing world. For instance, in a study in Ecuador, micronutrient deficiencies were found to be common in the elderly, especially for vitamin C, vitamin D, vitamin B-6, vitamin B-12, folic acid, and zinc, and these are thought to weaken the immune system or cause anemia and thus place people at greater risk of respiratory infections such as influenza. Seasonal variation in sunlight exposure, which is required for vitamin D synthesis within the body, has been proposed as one of the factors accounting for the seasonality of influenza. A meta-analysis of 13 studies indicated some support for adjunctive vitamin D therapy for influenza, but called for more rigorous clinical trials to settle the issue conclusively.

A recent review discussing herbal and alternative medicines in influenza treatment details evidence suggesting that N-acetylcysteine, elderberry, or a combination of Eleutherococcus senticosus and Andrographis paniculata may help to shorten the course of influenza infection. The article cites more limited evidence including animal or in vitro studies to suggest possible benefit from vitamin C, DHEA, high lactoferrin whey protein, Echinacea spp., Panax quinquefolium, Larix occidentalis arabinogalactans, elenolic acid (a constituent of olive leaf extract), Astragalus membranaceus, and Isatis tinctoria or Isatis indigotica. Another review assessed the quality of evidence for alternative influenza treatments, it concluded that there was "no compelling evidence" that any of these treatments were effective and that the available data on these products is particularly weak, with trials in this area suffering from many shortcomings, such as being small and poorly-designed and not testing for adverse effects.

N-Acetylcysteine

The activity of N-acetylcysteine (NAC) against influenza was first suggested in 1966. In 1997 a randomized clinical trial found that volunteers taking 1.2 grams of N-acetylcysteine daily for six months were as likely as those taking placebo to be infected by influenza, but only 25% of them experienced clinical symptoms, as contrasted with 67% of the control group. The authors concluded that resistance to flu symptoms was associated with a shift in cell mediated immunity from anergy toward normoergy, as measured by the degree of skin reactivity to seven common antigens such as tetanus and Candida albicans.

Several animal studies found that in a mouse model of lethal infection with a high dose of influenza, oral supplementation with one gram of N-acetylcysteine per kilogram of body weight daily increased the rate of survival, either when administered alone or in combination with the antiviral drugs ribavirin or oseltamivir. NAC was shown to block or reduce cytopathic effects in influenza-infected macrophages, to reduce DNA fragmentation (apoptosis) in equine influenza-infected canine kidney cells, and to reduce RANTES production in cultured airway cells in response to influenza virus by 18%. The compound has been proposed for treatment of influenza.

Elderberry

A few news reports have suggested the use of an elderberry (Sambucus nigra) extract as a potential preventative against the 2009 flu pandemic. The preparation has been reported to reduce the duration of influenza symptoms by raising levels of cytokines. However, the use of the preparation has been described as "imprudent" when an influenza strain causes death in healthy adults by cytokine storm leading to primary viral pneumonia. The manufacturer cites a lack of evidence for cytokine-related risks, but labels the product only as an antioxidant and food supplement.

"Kan Jang"

The mixture of Eleutherococcus senticosus ("Siberian ginseng") and Andrographis paniculata, sold under the trade name Kan Jang, was reported in the Journal of Herbal Pharmacotherapy to outperform amantadine in reducing influenza-related sick time and complications in a Volgograd pilot study of 71 patients in 2003. Prior to this, an extract of Eleutherococcus senticosus was shown to inhibit replication of RNA but not DNA viruses in vitro. Among nine Chinese medicinal herbs tested, Andrographis paniculata was shown to be most effective in inhibiting RANTES secretion by H1N1 influenza infected cells in cell culture, with an IC50 for the ethanol extract of 1.2 milligrams per liter.

Green Tea

High dietary intake of green tea (specifically, catechins and theanine that is found in tea products) has been correlated with reduced risk of contracting influenza, as well as having an antiviral effect upon types A and B. Specifically, the high levels of epigallocatechin gallate, epicatechin gallate, and epigallocatechin present in green tea were found to inhibit influenza virus replication. Additionally, topical application has been suggested to possibly act as a mild disinfectant. Regular dietary intake of green tea has been associated with stronger immune response to infection, through the enhancement of T-Cell function.

Passive immunity

Transfused antibodies

An alternative to vaccination used in the 1918 flu pandemic was the direct transfusion of blood, plasma, or serum from recovered patients. Though medical experiments of the era lacked some procedural refinements, eight publications from 1918-1925 reported that the treatment could approximately halve the mortality in hospitalized severe cases with an average case-fatality rate of 37% when untreated.

Bovine colostrum might also serve as a source of antibodies for some applications.

Ex vivo culture of T lymphocytes

Human T lymphocytes can be expanded in vitro using beads holding specific antigens to activate the cells and stimulate growth. Clonal populations of CD8+ cytotoxic T cells have been grown which carry T cell receptors specific to influenza. These work much like antibodies but are permanently bound to these cells. (See cellular immunity). High concentrations of N-acetylcysteine have been used to enhance growth of these cells. This method is still in early research.

Representation of a Lie group

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Representation_of_a_Lie_group...