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How does laughing gas (N₂O) work?

How does laughing gas (N₂O) work?


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Laughing gas (N2O), well, makes people laugh.

How does just a gas make us do that, there has to be some hormones at work…

So, I wanted to know how this works? What is the mechanism?


This information is all strictly for Entonox - a brand of analgesic gas comprising 50% Oxygen (O2) and 50% Nitrous Oxide (N2O), Laughing Gas. This mixture is known as 'Gas and Air' and is in very common use.

The active ingredient in Entonox is of course the nitrous oxide, so the discussion of the mechanism below refers solely to the N2O as you asked for.

Nitrous oxide enters the blood by diffusion from the alveoli whilst it is being inhaled, but does not bind with haemoglobin. It is fat soluble so quickly moves into cells, including synapse ends in the brain. Because of the stability of the compound, N2O is not metabolised by the body so has its effect as that molecule, then is eliminated by diffusion out of the lungs once inhalation has ceased (taking roughly 2 minutes for on and offset).

According to the material that BOC pharmaceuticals provide, the exact mechanism of the analgesia is not fully understood. It is known, however, to induce "inconsistent changes in the basal levels of thalamic nuclei".

N2O inhibits NMDA receptors in the brain whilst simultaneously encouraging the stimulation of the parasympathetic GABA receptors. This eventually produces an anaesthetic effect. It is also understood that N2O promotes the release of endogenous opioid neurotransmitters ('natural painkillers' e.g. endorphins) that specifically activate descending pain pathways. This inhibits the transmission of pain. In this way the analgesia provided by nitrous oxide is antinociceptive (literally pain reducing) rather than a generalised limbic depressor.

However, nitrous oxide also positively effects potassium ion channels too [ref] - reducing the chance of an action potential being generated in affected neurons. Research into this area of the effects of N2O is ongoing.

Euphoria is a common side effect of N2O usage, hence the name laughing gas. This is as part of wider emotional changes that can occur when nitrous oxide is being administered. For example, some people instead of laughing become scared or in other cases extremely aggressive towards those nearby. The emotional excitement may result in depressive or manic behaviour even to the point of psychosis and hallucinations especially in those who have a preexisting vulnerability to mental illness. The precise mechanism for these disinhibiting is again not fully understood.

Whilst it seems a lot of the answers are missing, the course I'm taking this information from is available online at Discover Entonox - modules 8-10 have relevance to this question. It's free to register and view the materials, they're all nicely narrated with diagrams etc.


How to Make Nitrous Oxide (Laughing Gas)

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    • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
    • B.A., Physics and Mathematics, Hastings College

    You can easily make nitrous oxide, or laughing gas, in the lab or at home. However, there are reasons why you might want to forgo the preparation unless you have chem lab experience.


    What does the treatment with nitrous oxide cost at the dentist?

    Not only patients with a pronounced fear of dentists benefit from the advantages of nitrous oxide treatment. This gentle method of sedation is suitable for adults and children alike and makes treatment noticeably easier. In an interview with the cost check expert, we clarify the costs of laughing gas at the dentist and answer many other questions.

    How does nitrous oxide work??

    Check cost: Sedation using nitrous oxide (nitrogen oxide, N₂O) is a safe and proven variant of anesthesia that has been used since the 19th century. Laughing gas temporarily dampens the function of the central nervous system, it has an analgesic and relaxing effect. Anxiety about treatment is resolved. The unpleasant gag reflex and other unpleasant sensations are also noticeably reduced.

    The perception of time is positively influenced and you have the feeling that the treatment time passes stress-free and much faster. This is particularly advantageous when there is a need for complex therapy. However, unlike general anesthesia, you remain conscious and responsive.

    What does the nitrous oxide treatment cost??

    Check cost: The cost of treatment with nitrous oxide depends on the effort and duration of the therapy.

    duration costs
    first 30 minutes 80 EUR
    every other half hour 50 EUR

    Accordingly, for an average treatment Costs around 100 – 150 EUR.

    The statutory health insurance comes the cost?

    The public health insurance companies do not pay for the nitrous oxide treatment Check cost: The statutory health insurers do not cover the costs of nitrous oxide treatment. This type of sedation is also not always included in the scope of services provided by private health insurers and dental insurance companies. You can find out whether and to what extent the insurance covers the costs in the insurance contract.

    For whom is laughing gas suitable??

    Check cost: Anxiety patients and children in particular benefit from treatment with nitrous oxide. Root canal treatments, implantations, time-consuming periodontal treatments, a necessary bone augmentation or several dental fillings, which should be set at one appointment, are no longer frightened by nitrous oxide.

    How does a nitrous oxide treatment work??

    Check cost: This is done in five steps:

    treatment step Explanation
    Select nose mask These are available in different fits. Many dentists also offer different scents.
    introduction First you get 100% oxygen. The addition of nitrous oxide is gradually increased until the desired effect occurs.
    Local anesthetic Only when the sensation of pain is reduced by the nitrous oxide does the dentist additionally apply a local anesthetic.
    treatment Inhale the laughing gas throughout the treatment period.
    Recovery When the therapy is complete, you will receive pure oxygen for a few minutes until the effects of the nitrous oxide have completely subsided.

    You can leave the practice unaccompanied just 15 to 30 minutes after taking off the breathing mask. One hour after ingestion, the gas has been completely excreted from the body.

    Can I drive a car after the nitrous oxide treatment??

    Check cost: Driving with nitrous oxide will not affect your ability to drive. As soon as you are allowed to leave the practice, you can participate in road traffic without restrictions.

    How safe is nitrous oxide?

    Check cost: Nitrous oxide treatment is very safe it has long been standard in almost all dental practices in numerous countries. Laughing gas has also been used successfully in Germany for many years without complications.

    Pure laughing gas owes its bad reputation to the violent effects of uncontrolled and undiluted inhalation. However, nitrous oxide is used as a sedative in dentistry in concentrations of at most 35 percent and is therefore free of side effects. In Scandinavia, Canada and the USA, over 70 percent of dentists offer stress-free nitrous oxide treatment.

    Who shouldn’t be treated with nitrous oxide?

    In principle, everyone can be sedated with nitrous oxide Check cost: There are few medical contraindications allergies to nitrous oxide are also not known.

    If you have a cold and breathing through your nose is difficult, nitrous oxide treatment can be difficult. If there are serious general illnesses such as MS, COPD, pneumothorax, pulmonary emphysema or ileus, the doctor should speak in detail about the use of nitrous oxide.

    Severe asthmatics and people taking antidepressants should not be treated with nitrous oxide. In the case of pregnant women, sedation gas is not recommended for reasons of safety. In the case of non-cooperative patients, for example small children or patients with a disability, treatment under general anesthesia is generally preferable.

    What side effects can occur?

    Check cost: The nitrous oxide treatment is almost always free of side effects. In rare cases:

    • nausea
    • dizziness
    • bloating
    • Numbness in arms and legs
    • a headache
    • temporary drowsiness
    • brief euphoria

    on. Serious side effects are usually due to an uncontrolled overdose. This can almost be ruled out during dental treatment.

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    A Little Laughing Gas Can Help Treat Depression, Small Study Finds

    A dose of laughing gas may just help some people with hard-to-treat depression, suggests a new, small clinical trial published Wednesday. The study found that people who inhaled nitrous oxide reported improvements in their depression symptoms afterward. It also found that people felt similar improvements with a smaller dose as they did with a larger one, but experienced substantially fewer side effects.

    Nitrous oxide (N₂O) is a colorless, non-flammable gas at room temperature that’s long been used as an anesthetic and sometimes as a recreational drug, due to the euphoria and dissociative hallucinations it can cause upon inhalation. But several years ago, Peter Nagele, a researcher and trauma anesthesiologist at the University of Chicago, and his colleagues began looking into nitrous oxide as a potential treatment for depression.

    “It started with the observation that ketamine, a different anesthetic with similar mechanistic properties like nitrous oxide (likely via NMDA-receptor blockage), was found to be a rapid antidepressant that also worked in patients with treatment-resistant depression,” Nagele told Gizmodo in an email. “By connecting these dots, we hypothesized that nitrous oxide may also be an antidepressant.”

    Their early research has suggested that inhaling a hour’s worth of nitrous oxide, mixed at 50% concentration with oxygen, could have “rapid and marked antidepressant effects” in patients with treatment-resistant depression. This new study, published Wednesday in Science Translational Medicine, is a Phase II controlled trial of the treatment. These sorts of trials are used to further figure out a potential drug’s efficacy and safety, oftentimes by testing out different doses.

    The small trial recruited 28 participants in a crossover design, which is when all the volunteers go through each of the trial’s conditions and their responses are compared to one another (as opposed to two or more distinct groups that either take the drug or placebo). In this case, that meant the volunteers, who had depression for an average of 17.5 years, had three treatment sessions: one where they inhaled a 50% dose of nitrous oxide, another where they inhaled a 25% dose, and one where they inhaled oxygen (the placebo). Afterwards, the volunteers took surveys meant to assess their level of depression.

    Ultimately, 24 people participated in at least one treatment session, and 20 took all the treatments. The team found that these volunteers on average experienced a greater improvement in depression symptoms when they took the nitrous oxide at either dose than they did after taking the placebo (based on the primary survey they completed)—an improvement that lasted for up to two weeks. They also found that both doses seemed to provide similar relief, but that people were more likely to experience side-effects like headaches, nausea, and lightheadedness from the larger dose.

    The findings are based on a very small sample size, so they shouldn’t be given too much weight right now. But Nagale’s other research has suggested that for some people who haven’t responded to other treatments, nitrous oxide may trigger a profound recovery. In at least one case, published last year, a patient with severe depression seemed to experience a complete remission following a single session of 50% nitrous oxide—a remission that had endured a month later. A form of ketamine has also since become an FDA-approved depression treatment, further raising hopes that nitrous oxide could be taken seriously as an antidepressant.

    Nagale and his team are planning to team up with other researchers to conduct larger trials at multiple locations (a key part of showing a drug really works), while also trying to study exactly how it seems to be affecting the brains of those with depression for the better. But it’s likely that the future of this treatment will depend on public and non-commercial funding, Nagale said, pointing to the example of ketamine.

    Some doctors and patients had been using generic ketamine, taken through IV, as an experimental depression treatment for years. But Johnson & Johnson didn’t fund expensive clinical trials to secure an approval for ketamine as a depression treatment it instead developed a patentable form taken as a nasal spray, called esketamine . That sort of commercialization isn’t something that’s possible with nitrous oxide, according to Nagale.

    “It is unlikely that a pharmaceutical company will be interested, as nitrous oxide is off-patent and there is no analogue or enantiomer it may need funding from the NIH and academic investigators taking the lead,” he said.

    Born and raised in NYC, Ed covers public health, disease, and weird animal science for Gizmodo. He has previously reported for the Atlantic, Vice, Pacific Standard, and Undark Magazine.


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    Contents

    Rocket motors Edit

    Nitrous oxide may be used as an oxidiser in a rocket motor. This is advantageous over other oxidisers in that it is much less toxic, and due to its stability at room temperature is also easier to store and relatively safe to carry on a flight. As a secondary benefit, it may be decomposed readily to form breathing air. Its high density and low storage pressure (when maintained at low temperature) enable it to be highly competitive with stored high-pressure gas systems. [12]

    In a 1914 patent, American rocket pioneer Robert Goddard suggested nitrous oxide and gasoline as possible propellants for a liquid-fuelled rocket. [13] Nitrous oxide has been the oxidiser of choice in several hybrid rocket designs (using solid fuel with a liquid or gaseous oxidiser). The combination of nitrous oxide with hydroxyl-terminated polybutadiene fuel has been used by SpaceShipOne and others. It also is notably used in amateur and high power rocketry with various plastics as the fuel.

    Nitrous oxide also may be used in a monopropellant rocket. In the presence of a heated catalyst, N
    2 O will decompose exothermically into nitrogen and oxygen, at a temperature of approximately 1,070 °F (577 °C). [14] Because of the large heat release, the catalytic action rapidly becomes secondary, as thermal autodecomposition becomes dominant. In a vacuum thruster, this may provide a monopropellant specific impulse (Isp) of as much as 180 s. While noticeably less than the Isp available from hydrazine thrusters (monopropellant or bipropellant with dinitrogen tetroxide), the decreased toxicity makes nitrous oxide an option worth investigating.

    Internal combustion engine Edit

    In vehicle racing, nitrous oxide (often referred to as just "nitrous") allows the engine to burn more fuel by providing more oxygen during combustion. The increase in oxygen allows for an increase in the injection of fuel, allowing the engine to produce more engine power. The gas is not flammable at a low pressure/temperature, but it delivers more oxygen than atmospheric air by breaking down at elevated temperatures, about 570 degrees F (

    300C). Therefore, it often is mixed with another fuel that is easier to deflagrate. Nitrous oxide is a strong oxidising agent, roughly equivalent to hydrogen peroxide, and much stronger than oxygen gas.

    Nitrous oxide is stored as a compressed liquid the evaporation and expansion of liquid nitrous oxide in the intake manifold causes a large drop in intake charge temperature, resulting in a denser charge, further allowing more air/fuel mixture to enter the cylinder. Sometimes nitrous oxide is injected into (or prior to) the intake manifold, whereas other systems directly inject, right before the cylinder (direct port injection) to increase power.

    The technique was used during World War II by Luftwaffe aircraft with the GM-1 system to boost the power output of aircraft engines. Originally meant to provide the Luftwaffe standard aircraft with superior high-altitude performance, technological considerations limited its use to extremely high altitudes. Accordingly, it was only used by specialised planes such as high-altitude reconnaissance aircraft, high-speed bombers and high-altitude interceptor aircraft. It sometimes could be found on Luftwaffe aircraft also fitted with another engine-boost system, MW 50, a form of water injection for aviation engines that used methanol for its boost capabilities.

    One of the major problems of using nitrous oxide in a reciprocating engine is that it can produce enough power to damage or destroy the engine. Very large power increases are possible, and if the mechanical structure of the engine is not properly reinforced, the engine may be severely damaged, or destroyed, during this kind of operation. It is very important with nitrous oxide augmentation of petrol engines to maintain proper operating temperatures and fuel levels to prevent "pre-ignition", [18] or "detonation" (sometimes referred to as "knock"). Most problems that are associated with nitrous oxide do not come from mechanical failure due to the power increases. Since nitrous oxide allows a much denser charge into the cylinder, it dramatically increases cylinder pressures. The increased pressure and temperature can cause problems such as melting the piston or valves. It also may crack or warp the piston or head and cause pre-ignition due to uneven heating.

    Automotive-grade liquid nitrous oxide differs slightly from medical-grade nitrous oxide. A small amount of sulfur dioxide ( SO
    2 ) is added to prevent substance abuse. [19] Multiple washes through a base (such as sodium hydroxide) can remove this, decreasing the corrosive properties observed when SO
    2 is further oxidised during combustion into sulfuric acid, making emissions cleaner. [ citation needed ]

    Aerosol propellant Edit

    The gas is approved for use as a food additive (E number: E942), specifically as an aerosol spray propellant. Its most common uses in this context are in aerosol whipped cream canisters and cooking sprays.

    The gas is extremely soluble in fatty compounds. In aerosol whipped cream, it is dissolved in the fatty cream until it leaves the can, when it becomes gaseous and thus creates foam. Used in this way, it produces whipped cream which is four times the volume of the liquid, whereas whipping air into cream only produces twice the volume. If air were used as a propellant, oxygen would accelerate rancidification of the butterfat, but nitrous oxide inhibits such degradation. Carbon dioxide cannot be used for whipped cream because it is acidic in water, which would curdle the cream and give it a seltzer-like "sparkling" sensation.

    The whipped cream produced with nitrous oxide is unstable, however, and will return to a more liquid state within half an hour to one hour. [20] Thus, the method is not suitable for decorating food that will not be served immediately.

    During December 2016, some manufacturers reported a shortage of aerosol whipped creams in the United States due to an explosion at the Air Liquide nitrous oxide facility in Florida in late August. With a major facility offline, the disruption caused a shortage resulting in the company diverting the supply of nitrous oxide to medical clients rather than to food manufacturing. The shortage came during the Christmas and holiday season when canned whipped cream use is normally at its highest. [21]

    Similarly, cooking spray, which is made from various types of oils combined with lecithin (an emulsifier), may use nitrous oxide as a propellant. Other propellants used in cooking spray include food-grade alcohol and propane.

    Medicine Edit

    Nitrous oxide has been used in dentistry and surgery, as an anaesthetic and analgesic, since 1844. [22] In the early days, the gas was administered through simple inhalers consisting of a breathing bag made of rubber cloth. [23] Today, the gas is administered in hospitals by means of an automated relative analgesia machine, with an anaesthetic vaporiser and a medical ventilator, that delivers a precisely dosed and breath-actuated flow of nitrous oxide mixed with oxygen in a 2:1 ratio.

    Nitrous oxide is a weak general anaesthetic, and so is generally not used alone in general anaesthesia, but used as a carrier gas (mixed with oxygen) for more powerful general anaesthetic drugs such as sevoflurane or desflurane. It has a minimum alveolar concentration of 105% and a blood/gas partition coefficient of 0.46. The use of nitrous oxide in anaesthesia, however, can increase the risk of postoperative nausea and vomiting. [24] [25] [26]

    Dentists use a simpler machine which only delivers an N
    2 O / O
    2 mixture for the patient to inhale while conscious. The patient is kept conscious throughout the procedure, and retains adequate mental faculties to respond to questions and instructions from the dentist. [27]

    Inhalation of nitrous oxide is used frequently to relieve pain associated with childbirth, trauma, oral surgery and acute coronary syndrome (includes heart attacks). Its use during labour has been shown to be a safe and effective aid for birthing women. [28] Its use for acute coronary syndrome is of unknown benefit. [29]

    In Britain and Canada, Entonox and Nitronox are used commonly by ambulance crews (including unregistered practitioners) as rapid and highly effective analgesic gas.

    Fifty percent nitrous oxide can be considered for use by trained non-professional first aid responders in prehospital settings, given the relative ease and safety of administering 50% nitrous oxide as an analgesic. The rapid reversibility of its effect would also prevent it from precluding diagnosis. [30]

    Recreational use Edit

    Recreational inhalation of nitrous oxide, with the purpose of causing euphoria and/or slight hallucinations, began as a phenomenon for the British upper class in 1799, known as "laughing gas parties".

    Starting in the nineteenth century, widespread availability of the gas for medical and culinary purposes allowed the recreational use to expand greatly throughout the world. In the United Kingdom, as of 2014, nitrous oxide was estimated to be used by almost half a million young people at nightspots, festivals and parties. [31] The legality of that use varies greatly from country to country, and even from city to city in some countries.

    Widespread recreational use of the drug throughout the UK was featured in the 2017 Vice documentary Inside The Laughing Gas Black Market, in which journalist Matt Shea met with dealers of the drug who stole it from hospitals, [32] although with nitrous oxide canisters being readily available online, the incidents of hospital theft are expected to be extremely rare.

    A significant issue cited in London's press is the effect of nitrous oxide canister littering, which is highly visible and causes significant complaint from communities. [33]

    The major safety hazards of nitrous oxide come from the fact that it is a compressed liquefied gas, an asphyxiation risk and a dissociative anaesthetic.

    While relatively non-toxic, nitrous oxide has a number of recognised ill effects on human health, whether through breathing it in or by contact of the liquid with skin or eyes.

    Nitrous oxide is a significant occupational hazard for surgeons, dentists and nurses. Because nitrous oxide is minimally metabolised in humans (with a rate of 0.004%), it retains its potency when exhaled into the room by the patient, and can pose an intoxicating and prolonged exposure hazard to the clinic staff if the room is poorly ventilated. Where nitrous oxide is administered, a continuous-flow fresh-air ventilation system or N
    2 O scavenger system is used to prevent a waste-gas buildup.

    The National Institute for Occupational Safety and Health recommends that workers' exposure to nitrous oxide should be controlled during the administration of anaesthetic gas in medical, dental and veterinary operators. [34] It set a recommended exposure limit (REL) of 25 ppm (46 mg/m 3 ) to escaped anaesthetic. [35]

    Mental and manual impairment Edit

    Exposure to nitrous oxide causes short-term decreases in mental performance, audiovisual ability and manual dexterity. [36] These effects coupled with the induced spatial and temporal disorientation could result in physical harm to the user from environmental hazards. [37]

    Neurotoxicity and neuroprotection Edit

    Like other NMDA receptor antagonists, N
    2 O was suggested to produce neurotoxicity in the form of Olney's lesions in rodents upon prolonged (several hour) exposure. [38] [39] [40] [41] New research has arisen suggesting that Olney's lesions do not occur in humans, however, and similar drugs such as ketamine are now believed not to be acutely neurotoxic. [42] [43] It has been argued that, because N
    2 O has a very short duration under normal circumstances, it is less likely to be neurotoxic than other NMDAR antagonists. [44] Indeed, in rodents, short-term exposure results in only mild injury that is rapidly reversible, and neuronal death occurs only after constant and sustained exposure. [38] Nitrous oxide also may cause neurotoxicity after extended exposure because of hypoxia. This is especially true of non-medical formulations such as whipped-cream chargers (also known as "whippets" or "nangs"), [45] which never contain oxygen, since oxygen makes cream rancid. [46]

    Additionally, nitrous oxide depletes vitamin B12 levels. This can cause serious neurotoxicity if the user has preexisting vitamin B12 deficiency. [47]

    Nitrous oxide at 75% by volume reduces ischemia-induced neuronal death induced by occlusion of the middle cerebral artery in rodents, and decreases NMDA-induced Ca 2+ influx in neuronal cell cultures, a critical event involved in excitotoxicity. [44]

    DNA damage Edit

    Occupational exposure to ambient nitrous oxide has been associated with DNA damage, due to interruptions in DNA synthesis. [48] This correlation is dose-dependent [49] [50] and does not appear to extend to casual recreational use however, further research is needed to confirm the duration and quantity of exposure needed to cause damage.

    Oxygen deprivation Edit

    If pure nitrous oxide is inhaled without oxygen mixed in, this can eventually lead to oxygen deprivation resulting in loss of blood pressure, fainting and even heart attacks. This can occur if the user inhales large quantities continuously, as with a strap-on mask connected to a gas canister. It can also happen if the user engages in excessive breath-holding or uses any other inhalation system that cuts off a supply of fresh air. [51] A further risk is that symptoms of frostbite can occur on the lips, larynx and bronchi if the gas is inhaled directly from the gas container. Therefore, condoms or balloons are often used to inhale nitrous oxide from. [52]

    Vitamin B12 deficiency Edit

    Long-term exposure to nitrous oxide may cause vitamin B12 deficiency. It inactivates the cobalamin form of vitamin B12 by oxidation. Symptoms of vitamin B12 deficiency, including sensory neuropathy, myelopathy and encephalopathy, may occur within days or weeks of exposure to nitrous oxide anaesthesia in people with subclinical vitamin B12 deficiency.

    Symptoms are treated with high doses of vitamin B12, but recovery can be slow and incomplete. [53]

    People with normal vitamin B12 levels have stores to make the effects of nitrous oxide insignificant, unless exposure is repeated and prolonged (nitrous oxide abuse). Vitamin B12 levels should be checked in people with risk factors for vitamin B12 deficiency prior to using nitrous oxide anaesthesia. [54]

    Prenatal development Edit

    Several experimental studies in rats indicate that chronic exposure of pregnant females to nitrous oxide may have adverse effects on the developing fetus. [55] [56] [57]

    Chemical/physical risks Edit

    At room temperature (20 °C [68 °F]) the saturated vapour pressure is 50.525 bar, rising up to 72.45 bar at 36.4 °C (97.5 °F)—the critical temperature. The pressure curve is thus unusually sensitive to temperature. [58]

    As with many strong oxidisers, contamination of parts with fuels have been implicated in rocketry accidents, where small quantities of nitrous/fuel mixtures explode due to "water hammer"-like effects (sometimes called "dieseling"—heating due to adiabatic compression of gases can reach decomposition temperatures). [59] Some common building materials such as stainless steel and aluminium can act as fuels with strong oxidisers such as nitrous oxide, as can contaminants that may ignite due to adiabatic compression. [60]

    There also have been incidents where nitrous oxide decomposition in plumbing has led to the explosion of large tanks. [15]

    The pharmacological mechanism of action of N
    2 O in medicine is not fully known. However, it has been shown to directly modulate a broad range of ligand-gated ion channels, and this likely plays a major role in many of its effects. It moderately blocks NMDAR and β2-subunit-containing nACh channels, weakly inhibits AMPA, kainate, GABAC and 5-HT3 receptors, and slightly potentiates GABAA and glycine receptors. [61] [62] It also has been shown to activate two-pore-domain K +
    channels. [63] While N
    2 O affects quite a few ion channels, its anaesthetic, hallucinogenic and euphoriant effects are likely caused predominantly, or fully, via inhibition of NMDA receptor-mediated currents. [61] [64] In addition to its effects on ion channels, N
    2 O may act to imitate nitric oxide (NO) in the central nervous system, and this may be related to its analgesic and anxiolytic properties. [64] Nitrous oxide is 30 to 40 times more soluble than nitrogen.

    The effects of inhaling sub-anaesthetic doses of nitrous oxide have been known to vary, based on several factors, including settings and individual differences [65] [66] however, from his discussion, Jay (2008) [37] suggests that it has been reliably known to induce the following states and sensations:

    • Intoxication
    • Euphoria/dysphoria
    • Spatial disorientation
    • Temporal disorientation
    • Reduced pain sensitivity

    A minority of users also will present with uncontrolled vocalisations and muscular spasms. These effects generally disappear minutes after removal of the nitrous oxide source. [37]

    Euphoric effect Edit

    In rats, N
    2 O stimulates the mesolimbic reward pathway by inducing dopamine release and activating dopaminergic neurons in the ventral tegmental area and nucleus accumbens, presumably through antagonisation of NMDA receptors localised in the system. [67] [68] [69] [70] This action has been implicated in its euphoric effects and, notably, appears to augment its analgesic properties as well. [67] [68] [69] [70]

    It is remarkable, however, that in mice, N
    2 O blocks amphetamine-induced carrier-mediated dopamine release in the nucleus accumbens and behavioural sensitisation, abolishes the conditioned place preference (CPP) of cocaine and morphine, and does not produce reinforcing (or aversive) effects of its own. [71] [72] Effects of CPP of N
    2 O in rats are mixed, consisting of reinforcement, aversion and no change. [73] In contrast, it is a positive reinforcer in squirrel monkeys, [74] and is well known as a drug of abuse in humans. [75] These discrepancies in response to N
    2 O may reflect species variation or methodological differences. [72] In human clinical studies, N
    2 O was found to produce mixed responses, similarly to rats, reflecting high subjective individual variability. [76] [77]

    Anxiolytic effect Edit

    In behavioural tests of anxiety, a low dose of N
    2 O is an effective anxiolytic, and this anti-anxiety effect is associated with enhanced activity of GABAA receptors, as it is partially reversed by benzodiazepine receptor antagonists. Mirroring this, animals that have developed tolerance to the anxiolytic effects of benzodiazepines are partially tolerant to N
    2 O . [78] Indeed, in humans given 30% N
    2 O , benzodiazepine receptor antagonists reduced the subjective reports of feeling "high", but did not alter psychomotor performance, in human clinical studies. [79]

    Analgesic effect Edit

    The analgesic effects of N
    2 O are linked to the interaction between the endogenous opioid system and the descending noradrenergic system. When animals are given morphine chronically, they develop tolerance to its pain-killing effects, and this also renders the animals tolerant to the analgesic effects of N
    2 O . [80] Administration of antibodies that bind and block the activity of some endogenous opioids (not β-endorphin) also block the antinociceptive effects of N
    2 O . [81] Drugs that inhibit the breakdown of endogenous opioids also potentiate the antinociceptive effects of N
    2 O . [81] Several experiments have shown that opioid receptor antagonists applied directly to the brain block the antinociceptive effects of N
    2 O , but these drugs have no effect when injected into the spinal cord.

    Conversely, α2-adrenoceptor antagonists block the pain-reducing effects of N
    2 O when given directly to the spinal cord, but not when applied directly to the brain. [82] Indeed, α2B-adrenoceptor knockout mice or animals depleted in norepinephrine are nearly completely resistant to the antinociceptive effects of N
    2 O . [83] Apparently N
    2 O -induced release of endogenous opioids causes disinhibition of brainstem noradrenergic neurons, which release norepinephrine into the spinal cord and inhibit pain signalling. [84] Exactly how N
    2 O causes the release of endogenous opioid peptides remains uncertain.

    Nitrous oxide is a colourless, non-toxic gas with a faint, sweet odour.

    Nitrous oxide supports combustion by releasing the dipolar bonded oxygen radical, and can thus relight a glowing splint.

    N
    2 O is inert at room temperature and has few reactions. At elevated temperatures, its reactivity increases. For example, nitrous oxide reacts with NaNH
    2 at 460 K (187 °C) to give NaN
    3 :

    The above reaction is the route adopted by the commercial chemical industry to produce azide salts, which are used as detonators. [85]

    The gas was first synthesised in 1772 by English natural philosopher and chemist Joseph Priestley who called it phlogisticated nitrous air (see phlogiston theory) [86] or inflammable nitrous air. [87] Priestley published his discovery in the book Experiments and Observations on Different Kinds of Air (1775), where he described how to produce the preparation of "nitrous air diminished", by heating iron filings dampened with nitric acid. [88]

    Early use Edit

    The first important use of nitrous oxide was made possible by Thomas Beddoes and James Watt, who worked together to publish the book Considerations on the Medical Use and on the Production of Factitious Airs (1794). This book was important for two reasons. First, James Watt had invented a novel machine to produce "factitious airs" (including nitrous oxide) and a novel "breathing apparatus" to inhale the gas. Second, the book also presented the new medical theories by Thomas Beddoes, that tuberculosis and other lung diseases could be treated by inhalation of "Factitious Airs". [22]

    The machine to produce "Factitious Airs" had three parts: a furnace to burn the needed material, a vessel with water where the produced gas passed through in a spiral pipe (for impurities to be "washed off"), and finally the gas cylinder with a gasometer where the gas produced, "air", could be tapped into portable air bags (made of airtight oily silk). The breathing apparatus consisted of one of the portable air bags connected with a tube to a mouthpiece. With this new equipment being engineered and produced by 1794, the way was paved for clinical trials, [ clarification needed ] which began in 1798 when Thomas Beddoes established the "Pneumatic Institution for Relieving Diseases by Medical Airs" in Hotwells (Bristol). In the basement of the building, a large-scale machine was producing the gases under the supervision of a young Humphry Davy, who was encouraged to experiment with new gases for patients to inhale. [22] The first important work of Davy was examination of the nitrous oxide, and the publication of his results in the book: Researches, Chemical and Philosophical (1800). In that publication, Davy notes the analgesic effect of nitrous oxide at page 465 and its potential to be used for surgical operations at page 556. [89] Davy coined the name "laughing gas" for nitrous oxide. [90]

    Despite Davy's discovery that inhalation of nitrous oxide could relieve a conscious person from pain, another 44 years elapsed before doctors attempted to use it for anaesthesia. The use of nitrous oxide as a recreational drug at "laughing gas parties", primarily arranged for the British upper class, became an immediate success beginning in 1799. While the effects of the gas generally make the user appear stuporous, dreamy and sedated, some people also "get the giggles" in a state of euphoria, and frequently erupt in laughter. [91]

    One of the earliest commercial producers in the U.S. was George Poe, cousin of the poet Edgar Allan Poe, who also was the first to liquefy the gas. [92]

    Anaesthetic use Edit

    The first time nitrous oxide was used as an anaesthetic drug in the treatment of a patient was when dentist Horace Wells, with assistance by Gardner Quincy Colton and John Mankey Riggs, demonstrated insensitivity to pain from a dental extraction on 11 December 1844. [93] In the following weeks, Wells treated the first 12 to 15 patients with nitrous oxide in Hartford, Connecticut, and, according to his own record, only failed in two cases. [94] In spite of these convincing results having been reported by Wells to the medical society in Boston in December 1844, this new method was not immediately adopted by other dentists. The reason for this was most likely that Wells, in January 1845 at his first public demonstration to the medical faculty in Boston, had been partly unsuccessful, leaving his colleagues doubtful regarding its efficacy and safety. [95] The method did not come into general use until 1863, when Gardner Quincy Colton successfully started to use it in all his "Colton Dental Association" clinics, that he had just established in New Haven and New York City. [22] Over the following three years, Colton and his associates successfully administered nitrous oxide to more than 25,000 patients. [23] Today, nitrous oxide is used in dentistry as an anxiolytic, as an adjunct to local anaesthetic.

    Nitrous oxide was not found to be a strong enough anaesthetic for use in major surgery in hospital settings, however. Instead, diethyl ether, being a stronger and more potent anaesthetic, was demonstrated and accepted for use in October 1846, along with chloroform in 1847. [22] When Joseph Thomas Clover invented the "gas-ether inhaler" in 1876, however, it became a common practice at hospitals to initiate all anaesthetic treatments with a mild flow of nitrous oxide, and then gradually increase the anaesthesia with the stronger ether or chloroform. Clover's gas-ether inhaler was designed to supply the patient with nitrous oxide and ether at the same time, with the exact mixture being controlled by the operator of the device. It remained in use by many hospitals until the 1930s. [23] Although hospitals today use a more advanced anaesthetic machine, these machines still use the same principle launched with Clover's gas-ether inhaler, to initiate the anaesthesia with nitrous oxide, before the administration of a more powerful anaesthetic.

    As a patent medicine Edit

    Colton's popularisation of nitrous oxide led to its adoption by a number of less than reputable quacksalvers, who touted it as a cure for consumption, scrofula, catarrh and other diseases of the blood, throat and lungs. Nitrous oxide treatment was administered and licensed as a patent medicine by the likes of C. L. Blood and Jerome Harris in Boston and Charles E. Barney of Chicago. [96] [97]


    How Laughter Works

    ­First of all, laughter is not the same as humor. Laughter is the physiological respo­nse to humor. Laughter consists of two parts -- a set of gestures and the production of a sound. When we laugh, the brain pressures us to conduct both those activities simultaneously. When we laugh heartily, changes occur in many parts of the body, even the arm, leg and trunk muscles.

    Under certain conditions, our bodies perform what the Encyclopedia Britannica describes as "rhythmic, vocalized, expiratory and involuntary actions" -- better known as laughter. Fifteen facial muscles contract and stimulation of the zygomatic major muscle (the main lifting mechanism of your upper lip) occurs. Meanwhile, the respiratory system is upset by the epiglottis half-closing the larynx, so that air intake occurs irregularly, making you gasp. In extreme circumstances, the tear ducts are activated, so that while the mouth is opening and closing and the struggle for oxygen intake continues, the face becomes moist and often red (or purple). The noises that usually accompany this bizarre behavior range from sedate giggles to boisterous guffaws.

    ­Behavioral neurobiologist and pioneering laughter researcher Robert Provine jokes that he has encountered one major problem in his study ­of laughter. The problem is that laughter disappears just when he is ready to observe it -- especially in the laboratory. One of his studies looked at the sonic structure of laughter. He discovered that all human laughter consists of variations on a basic form that consists of short, vowel-like notes repeated every 210 milliseconds. Laughter can be of the "ha-ha-ha" variety or the "ho-ho-ho" type but not a mixture of both, he says. Provine also suggests that humans have a "detector" that responds to laughter by triggering other neural circuits in the brain, which, in turn, generates more laughter. This explains why laughter is contagious.

    Humor researcher Peter Derks describes laughter response as "a really quick, automatic type of behavior." "In fact, how quickly our brain recognizes the incongruity that lies at the heart of most humor and attaches an abstract meaning to it determines whether we laugh," he says.

    In the next section, we'll learn why we laugh.

    One of the key features of natural laughter is its placement in speech, linguists say. Laughter almost always occurs during pauses at the end of phrases. Experts say this suggests that an orderly process (probably neurologically based) governs the placement of laughter in speech and gives speech priority access to the single vocalization channel. This strong relationship between laughter and speech is much like punctuation in written communication -- that's why it's called the punctuation effect.


    What is the density of laughing gas, dinitrogen monoxide, n2o, at a temperature of 325 k and a pressure of 113.0 kpa?

    Where, P is the pressure of the gas (Pa), V is the volume of the gas (m³), n is the number of moles of gas (mol), R is the universal gas constant ( 8.314 J mol ⁻¹ K⁻ ¹) and T is temperature in Kelvin.

    Where, n is number of moles, m is mass and M is molar mass.

    From (2) and (3),
    PV = (m/M) RT

    By rearranging,
    P = (m/VM)RT (4)

    From (1) and (4)
    P = (dRT) / M

    The given data,
    P = 113.0 kPa = 113.0 x 10 ³ Pa
    d = ?
    R = 8.314 J mol ⁻¹ K⁻ ¹
    T = 325 K
    M = 44.0 g/mol = 44.0 x 10⁻³ kg/mol

    By substitution,

    113.0 x 10³ Pa = (d x 8.314 J mol⁻¹ K⁻¹ x 325 K) / 44.0 x 10⁻³ kg/mol

    d = (113.0 x 10³ Pa x 44.0 x 10⁻³ kg/mol) / (8.314 J mol⁻¹ K⁻¹ x 325 K )
    d = 1.84 kg m ⁻ ³

    Hence, the density of the N ₂O at 325 K and 113.0 kPa is 1.84 kg m⁻³.

    Assumption made is "N ₂O gas has an ideal gas behavior".


    Nitrogen fertilizers are incredibly efficient, but they make climate change a lot worse

    Sustainable farming can reduce nitrous oxide emissions. Credit: eutrophication & hypoxia/Flickr, CC BY-SA

    Nitrous oxide (N2O) (more commonly known as laughing gas) is a powerful contributor to global warming. It is 265 times more effective at trapping heat in the atmosphere than carbon dioxide and depletes our ozone layer.

    Human-driven N2O emissions have been growing unabated for many decades, but we may have been seriously underestimating by just how much. In a paper published today in Nature Climate Change, we found global emissions are higher and growing faster than are being reported.

    Although clearly bad news for the fight against climate change, some countries are showing progress towards reducing N2O emissions, without sacrificing the incredible crop yields allowed by nitrogen fertilizers. Those countries offer insights for the rest of the world.

    There are a number of natural and human sources of N2O emissions, which have remained relatively steady for millennia. However, in the early 20th century the Haber-Bosch process was developed, allowing industry to chemically synthesize molecular nitrogen from the atmosphere to create nitrogen fertilizer.

    This advancement kick-started the Green Revolution, one of the greatest and fastest human revolutions of our time. Crop yields across the world have increased many times over due to the use of nitrogen fertilizers and other improved farming practices.

    But when soil is exposed to abundant nitrogen in its active form (as in fertilizer), microbial reactions take place that release N2O emissions. The unrestricted use in nitrogen fertilizers, therefore, created a huge uptick in emissions.

    N2O is the third-most-important greenhouse gas after carbon dioxide and methane. As well as trapping heat, it depletes ozone in the stratosphere, contributing to the ozone hole. Once released into the atmosphere, N2O remains active for more than 100 years.

    N₂O concentrations (parts per billion) in air from Cape Grim Baseline Air Pollution Station (Tasmania, Australia) and air contained in bubbles trapped in firn and ice from the Law Dome, Antarctica. N₂O concentrations from these two sites reflect global concentrations, not local conditions. Credit: BoM/CSIRO/AAD.

    Tracking emissions from above

    Conventional analysis of N2O emissions from human activities are estimated from various indirect sources. This include country-by-country reporting, global nitrogen fertilizer production, the areal extent of nitrogen-fixing crops and the use of manure fertilizers.

    Our study instead used actual atmospheric concentrations of N2O from dozens of monitoring stations all over the world. We then used atmospheric modeling that explains how air masses move across and between continents to infer the expected emissions of specific regions.

    We found global N2O emissions have increased over the past two decades and the fastest growth has been since 2009. China and Brazil are two countries that stand out. This is associated with a spectacular increase in the use of nitrogen fertilizers and the expansion of nitrogen-fixing crops such as soybean.

    We also found the emissions reported for those two countries, based on a methodology developed by the Intergovernmental Panel on Climate Change, are significantly lower than those inferred from N2O levels in the atmosphere over those regions.

    This mismatch seems to arise from the fact that emissions in those regions are proportionally higher than the use of nitrogen fertilizers and manure. This is a departure from the linear relationship used to report emissions by most countries.

    There appears to be a level of nitrogen past which plants can no longer effectively use it. Once that threshold is passed in croplands, N2O emissions grow exponentially.

    N₂O emissions from agriculture estimated by using the emissions factors approach of the IPCC (blue), the calculated emission factor in this study (green), and the average of the atmospheric inversions in this study (black). Credit: Thompson et al. 2019 Nature Climate Change

    Reducing N2O emissions from agriculture will be very challenging, given the expected global growth in population, food demand and biomass-based products including energy.

    However, all future emission scenarios consistent with the goals of the Paris Agreement require N2O emissions to stop growing and, in most cases, to decline—between 10% and 30% by mid-century.

    Interestingly, emissions from the U.S. and Europe have not grown for over two decades, yet crop yields across these regions increased or remained steady. Both regions have created strong regulations largely to prevent excess accumulation of nitrogen in soils and into waterways.

    These areas and other studies have demonstrated the success of more sustainable farming in reducing emissions while increasing crop yields and farm-level economic gains.

    A whole toolbox of options is available to increase nitrogen use efficiency and reduce N2O emissions: precision applications of nitrogen in space and time, the use of N-fixing crops in rotations, reduced tillage or no-tillage, prevention of waterlogging, and the use of nitrification inhibitors.

    Regulatory frameworks have shown win-win outcomes in a number of countries. With intelligent adaptions to different nations' and regions' needs, they can also work elsewhere.

    This article is republished from The Conversation under a Creative Commons license. Read the original article.


    Nitrous oxide emissions 300 times more powerful than carbon dioxide are jeopardising Earth's future

    Credit: Shutterstock

    Nitrous oxide from agriculture and other sources is accumulating in the atmosphere so quickly it puts Earth on track for a dangerous 3℃ warming this century, our new research has found.

    Each year, more than 100 million tons of nitrogen are spread on crops in the form of synthetic fertilizer. The same amount again is put onto pastures and crops in manure from livestock.

    This colossal amount of nitrogen makes crops and pastures grow more abundantly. But it also releases nitrous oxide (N2O), a greenhouse gas.

    Agriculture is the main cause of the increasing concentrations, and is likely to remain so this century. N₂O emissions from agriculture and industry can be reduced, and we must take urgent action if we hope to stabilize Earth's climate.

    Where does nitrous oxide come from?

    We found that N2O emissions from natural sources, such as soils and oceans, have not changed much in recent decades. But emissions from human sources have increased rapidly.

    Atmospheric concentrations of N2O reached 331 parts per billion in 2018, 22% above levels around the year 1750, before the industrial era began.

    Agriculture caused almost 70% of global N2O emissions in the decade to 2016. The emissions are created through microbial processes in soils. The use of nitrogen in synthetic fertilizers and manure is a key driver of this process.

    2000 years of atmospheric nitrous oxide concentrations. Observations taken from ice cores and atmosphere. Credit: BoM/CSIRO/AAD

    Other human sources of N2O include the chemical industry, waste water and the burning of fossil fuels.

    N₂O is destroyed in the upper atmosphere, primarily by solar radiation. But humans are emitting N2O faster than it's being destroyed, so it's accumulating in the atmosphere.

    N₂O both depletes the ozone layer and contributes to global warming.

    As a greenhouse gas, N2O has 300 times the warming potential of carbon dioxide (CO2) and stays in the atmosphere for an average 116 years. It's the third most important greenhouse gas after CO2 (which lasts up to thousands of years in the atmosphere) and methane.

    N2O depletes the ozone layer when it interacts with ozone gas in the stratosphere. Other ozone-depleting substances, such as chemicals containing chlorine and bromine, have been banned under the United Nations Montreal Protocol. N2O is not banned under the protocol, although the Paris Agreement seeks to reduce its concentrations.

    Reducing fertiliser use on farms is critical to reducing N₂O emissions. Credit: Shutterstock

    The Intergovernmental Panel on Climate Change has developed scenarios for the future, outlining the different pathways the world could take on emission reduction by 2100. Our research found N₂O concentrations have begun to exceed the levels predicted across all scenarios.

    The current concentrations are in line with a global average temperature increase of well above 3℃ this century.

    We found that global human-caused N2O emissions have grown by 30% over the past three decades. Emissions from agriculture mostly came from synthetic nitrogen fertilizer used in East Asia, Europe, South Asia and North America. Emissions from Africa and South America are dominated by emissions from livestock manure.

    In terms of emissions growth, the highest contributions come from emerging economies—particularly Brazil, China, and India—where crop production and livestock numbers have increased rapidly in recent decades.

    N2O emissions from Australia have been stable over the past decade. Increase in emissions from agriculture and waste have been offset by a decline in emissions from industry and fossil fuels.

    Regional changes in N₂O emissions from human activities, from 1980 to 2016, in million tons of nitrogen per year. Data from: Tian et al. 2020, Nature. Credit: Global Carbon Project & International Nitrogen Initiative

    N₂O must be part of efforts to reduce greenhouse gas emissions, and there is already work being done. Since the late 1990s, for example, efforts to reduce emissions from the chemicals industry have been successful, particularly in the production of nylon, in the United States, Europe and Japan.

    Reducing emissions from agriculture is more difficult—food production must be maintained and there is no simple alternative to nitrogen fertilizers. But some options do exist.

    In Europe over the past two decades, N₂O emissions have fallen as agricultural productivity increased. This was largely achieved through government policies to reduce pollution in waterways and drinking water, which encouraged more efficient fertilizer use.

    Other ways to reduce N2O emissions from agriculture include:

    • better management of animal manure
    • applying fertilizer in a way that better matches the needs of growing plants
    • alternating crops to include those that produce their own nitrogen, such as legumes, to reduce the need for fertilizer
    • enhanced efficiency fertilizers that lower N₂O production.
    Global nitrous oxide budget 2007-16. Credit: Adopted from Tian et al. 2020. Nature. Source: Global Carbon Project & International Nitrogen Initiative.

    Getting to net-zero emissions

    Stopping the overuse of nitrogen fertilizers is not just good for the climate. It can also reduce water pollution and increase farm profitability.

    Even with the right agricultural policies and actions, synthetic and manure fertilizers will be needed. To bring the sector to net-zero greenhouse gas emissions, as needed to stabilize the climate, new technologies will be required.

    This article is republished from The Conversation under a Creative Commons license. Read the original article.


    Watch the video: Το αέριο του γέλιου, ένας εχθρός του κλίματος - futuris (July 2022).


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