Do you pump Octane 95 Petrol to your car to get better performance?
If your answer is YES, this article is for you
Dr. Saliya Jayasekara.
Senior Lecturer Department of Mechanical Engineering
University of Moratuwa
Many passenger vehicles, including three-wheelers and motorcycles are fueled by octane 95 gasoline when octane 92 gasoline (petrol) is available at a lower price.
Otto engine (petrol engine) is an internal combustion spark ignition engine invented by a German engineer Nicolaus Otto in 1876 and used in most of the light weight vehicles including cars, three wheelers and motor bicycles. Otto engines can burn most of the hydrocarbon fuels (including hydrogen and ethanol) that can mix with air by evaporation (low boiling point). But the combustion characteristics of different hydrocarbons are not the same when burned inside an engine. If an Otto engine is designed for a particular fuel, it would not perform similarly with a fuel that has a different chemical composition.
In a well-tuned Otto engine run on gasoline for which the engine is designed, the combustion of the gasoline (petrol) / air mixture will continue smoothly from the spark plug to the piston head by igniting successive layers of the mixture as shown in Figure 1 (a).
If low grade gasolines are used, the combustion of some of the air/ fuel mixture in the cylinder does not result from propagation of the flame front initiated by the spark plug, but one or more pockets of air/fuel mixture explode (Detonate) outside the envelope of the normal combustion front as shown in Figure 1 (b). This detonation can cause severe damage to the piston and the head of the engine while deteriorating thermal performance of the engine (low efficiency)
Gasoline is a petroleum-derived product comprising a mixture of different hydrocarbons ranging from 4 to 12 carbon atoms in a carbon chain with the boiling point ranging of 30–225°C. It is predominantly a mixture of paraffins, naphthenes, aromatics and olefins. Additives and blending agents are added to improve the performance and stability of gasoline. The engine designers learned that straight-chain paraffin have a much higher tendency to detonate than do branched-chain paraffin.
The tendency of a particular gasoline to detonate is expressed by its octane number (ON). Arbitrarily, tri-methyl-pentane, C8H18 (iso-octane) is assigned an ON of 100, while the straight-chain paraffin n-heptane, C7H16 is given an ON of zero. Hence, a fuel sample with the same anti-detonation quality as that of a mixture containing 90% iso-octane and 10% n-heptane is said to have an ON of 90. Gasoline is made up of a mixture of mostly branched-chain paraffin with suitable additives to give an ON in the range 90 –100. It was also learned through experiments that the ON of a gasoline blends (e.g. gasoline and ethanol) can be calculated by using weighted average ON of each compound. Most importantly, the octane number has nothing to do with the heating value (Calorific value) or the purity of the fuel.
Engine thermodynamics show that engines with a high compression ratio offer higher thermal performance than engines with a low compression ratio. These engines having high compression ratio require high octane gasoline (for example octane 95) to avoid detonation. However, using gasoline having higher octane ratings for the engines designed for a low octane rating (for example, 92 octane) would not provide an additional benefit or loss, other than increased fuel cost.
Therefore, it is important to know the designed octane number of the engine before fueling (refer owner’s manual of the vehicle). For example: the minimum ON requirement for two and three wheelers in south Asia is 87 (The World Bank). Most of the Toyota, Honda and Nissan models including hybrid engines recommend 92 octane gasoline.
Dr. Saliya Jayasekara received the B. Sc. degree in mechanical engineering from university of Moratuwa in 2001, and the M.Sc. and PhD degrees in decentralized power generation systems from Royal institute of technology Sweden and the Melbourne University Australia in 2004 and 2013 respectively. He has well over 13 years of national and international experience in design and installation of centralised/decentralised power plants, boilers (utility/package) and heat exchangers. Currently he is serving as a senior lecture at University of Moratuwa, a visiting lecturer and fellow at Deakin University Australia.
If you have a heart, say no to tobacco!
BY Dr. Gotabhya Ranasinghe
(MBBS, MD, FCCP, FRCP, FAPSIC, FACC, FESC)
Consultant in General & Interventional Cardiology, NHSL
Tobacco harms practically all of the body’s organs and is a key risk factor for heart disease!
Smoking can impact all aspects of the cardiovascular system, including the heart, blood, and blood vessels. I know from my experience over the years that about 25% of the patients who seek treatment from me for heart conditions smoke.
Is there a strong link between smoking and heart disease?
Of course, there is! Smoking definitely contributes to heart disease. The majority of smokers experience heart attacks.
Some claim that the only people at risk for heart attacks or strokes are those who are classified as heavy smokers. Although this is the case, did you know that smoking even one or two cigarettes a day might result in heart attacks?
Young smokers are on the rise, which unfortunately brings more cardiac patients between the ages of 20 and 25 to the cardiology unit.
Why is tobacco poison for your heart?
The harmful mix of more than 7,000 chemicals in cigarette smoke, including nicotine and carbon monoxide, can interfere with vital bodily functions when inhaled.
When you breathe, your lungs absorb oxygen and pass it on to your heart, which then pumps this oxygen-rich blood to the rest of your body through the blood arteries. However, when the blood that is circulated to the rest of the body picks up the toxins in cigarette smoke when you breathe it in, your heart and blood arteries are harmed by these substances, which could result in cardiovascular diseases.
What does cigarette smoke do to your heart?
Atherosclerosis (Building up of cholesterol deposits in the coronary artery)
Endothelium dysfunction leads to atherosclerosis. The inner layer of coronary arteries or the arterial wall of the heart both function improperly and contribute to artery constriction when you smoke cigarettes. As a
result, the endothelium-cell barrier that separates the arteries is breached, allowing cholesterol plaque to build up. It’s crucial to realize that smoking increases the risk of endothelial dysfunction in even those who have normal cholesterol levels.
The plaque accumulated in the arteries can burst as a result of continued smoking or other factors like emotional stress or strenuous exercises. Heart attacks occur when these plaque rupture and turn into clots.
Coronary artery spasm
Did you know you can experience a spasm immediately after a puff of smoke?
A brief tightening or constriction of the muscles in the wall of an artery that supplies blood to the heart is referred to as a coronary artery spasm. Part of the heart’s blood flow can be impeded or reduced by a spasm. A prolonged spasm can cause chest pain and possibly a heart attack.
People who usually experience coronary artery spasms don’t have typical heart disease risk factors like high cholesterol or high blood pressure. However, they are frequent smokers.
An erratic or irregular heartbeat is known as an arrhythmia. The scarring of the heart muscle caused by smoking can cause a fast or irregular heartbeat.Additionally, nicotine can cause arrhythmia by speeding up the heart rate.
One of the best things you can do for your heart is to stop smoking!
Did you know the positive impacts start to show as soon as you stop smoking?
After 20 minutes of quitting smoking, your heart rate begins to slow down.
In just 12 hours after quitting, the level of carbon monoxide in your blood returns to normal, allowing more oxygen to reach your heart and other vital organs.
12 to 24 hours after you stop smoking, blood pressure levels return to normal.
Your risk of developing coronary heart disease decreases by 50% after one year of no smoking.
So let us resolve to protect and improve heart health by saying no to tobacco!
Religious cauldron being stirred; filthy rich in abjectly poor country
What a ho ha over a silly standup comedian’s stupid remarks about Prince Siddhartha. I have never watched this Natasha Edirisuriya’s supposedly comic acts on YouTube or whatever and did not bother to access derogatory remarks she supposedly introduced to a comedy act of hers that has brought down remand imprisonment on her up until June 6. Speaking with a person who has his ear to the ground and to the gossip grape wine, I was told her being remanded was not for what she said but for trying to escape consequences by flying overseas – to Dubai, we presume, the haven now of drug kingpins, money launderers, escapees from SL law, loose gabs, and all other dregs of society.
Of course, derogatory remarks on any religion or for that matter on any religious leader have to be taboo and contraveners reprimanded publicly and perhaps imposed fines. However, imprisonment according to Cassandra is too severe.
Just consider how the Buddha treated persons who insulted him or brought false accusations against him including the most obnoxious and totally improbable accusation of fatherhood. Did he even protest, leave along proclaim his innocence. Did he permit a member of the Sangha to refute the accusations? Not at all! He said aloud he did not accept the accusations and insults. Then he asked where the accusations would go to? Back to sender/speaker/accuser. That was all he said.
Thus, any person or persons, or even all following a religion which is maligned should ignore what was said. Let it go back and reside with the sayer/maligner. Of course, the law and its enforcers must spring to action and do the needful according to the law of the land.
One wonders why this sudden spurt of insults arrowed to Buddhism. Of course, the aim is to denigrate the religion of the majority in the land. Also perhaps with ulterior motives that you and Cass do not even imagine. In The Island of Wednesday May 31, MP Dilan Perera of Nidahas Janatha Sabawa (difficult to keep pace with birth of new political parties combining the same words like nidahas and janatha to coin new names) accused Jerome Fernando and Natasha E as “actors in a drama orchestrated by the government to distract people from the real issues faced by the masses.”
We, the public, cannot simply pooh pooh this out of hand. But is there a deeper, subtler aim embedded in the loose talk of Jerome and his followers? Do we not still shudder and shake with fear and sympathy when we remember Easter Sunday 2019 with its radical Muslim aim of causing chaos? It is said and believed that the Muslim radicals wanted not only to disrupt Christian prayer services on a holy day but deliver a blow to tourism by bombing hotels.
Then their expectation was a backlash from the Sinhalese which they hoped to crush by beheading approaching Sinhala avenging attackers with swords they had made and stacked. This is not Cass’ imagination running riot but what a Catholic Priest told us when we visited the Katuwapitiya Church a couple of weeks after the dastardly bombing.
It is believed and has been proclaimed there was a manipulating group led by one demented person who egged the disasters on with the double-edged evil aim of disrupting the land and then promising future security if … Hence, we cannot be so naïve as to believe that Jerome and Natasha were merely careless speakers. Who knows what ulterior moves were dictated to by power-mad black persons and made to brew in the national cauldron of discontent? Easiest was to bring to the boil religious conflict, since the races seem to be co-living harmoniously, mostly after the example of amity set before the land and internationally of Sri Lankans of all races, religions, social statuses and ages being able to unite during the Aragalaya.
We have already suffered more than our fair share of religious conflict. The LTTE exploded a vehicle laden with bombs opposite the Dalada Maligawa; shot at the Sacred Bo Tree, massacred a busload of mostly very young Buddhist monks in Aranthalawa. This was on June 2, 1987, particularly pertinent today. They killed Muslims at prayer in a mosque in Katankudy after ethnically cleansing Jaffna and adjoining areas of Muslim populations.
The Sinhalese, led by ultra-nationalists and drunken goons ravaged Tamils in 1983 and then off and on conflicted with Muslims. Hence the need to nip all and every religious conflict in the bud; no preachers/ Buddhist monks/overzealous lay persons, or comedians and media persons to be allowed to malign religions and in the name of religion cause conflict, least of all conflagration.
Comes to mind the worst case of religious intolerance, hate, revenge and unthinkable cruelty. Cass means here the prolonged fatwa declared against Salman Rushdie (1947-), British American novelist of Indian origin who had a ransom set aside for his life declared by the then leader of Iran, Ruhollah Khomeini, soon after Rushdie’s novel Satanic Verses was published in 1988. The British government diligently ensured his safety by hiding him in various places. After nearly two decades of tight security around him, he ventured to the US on an invited visit. He settled down in New York, believing he was now safe from the fatwa and mad men. It was not to be. In New York on stage to deliver a lecture in 2022, Rushdie was set upon by a lone assailant who stabbed him in the eye, blinding him in that eye and necessitating his wearing an eye band. What on earth was his crime? Writing a fictitious story to succeed many he had written and won prizes for like the Booker.
Religious fanaticism must never be permitted to raise its devilish head wherever, whenever.
Farmer’s fabulously rich son
Often quoted is the phrase coined by the Tourist Board, Cass believes, to describe Sri Lanka. Land like no other. It was completely complementary and justified when it was first used. We were an almost unique island where every prospect pleased, particularly its smiling, easy going people and the wonderful terrain of the land with varying altitudes, climates and fauna and flora.
Then with the decline of the country engineered and wrought by evil, self-gratifying politicians, their sidekicks and dishonest bureaucrats, disparities became stark. Sri Lanka is now in the very dumps: bankrupt, its social, economic and sustainability fabric in shreds and people suffering immensely. But since it is a land like no other with a different connotation, only certain of its population suffer and undergo deprivation and hardship. Others live grand even now and have money stashed high in–house and overseas in banks, businesses and dubious off shore dealings. Some lack the few rupees needed to travel in a bus but most political bods drive around in luxury cars; infants cry for milk and children for a scrap of bread or handful of rice. Plain tea is drunk by many to quell pangs of hunger while the corrupt VIPs quaff champaign and probably have exotic foods flown over from gourmet venues.
And most of those who drive luxury cars, eat and drink exotically and live the GOOD life, did not inherit wealth, nor earn it legitimately. Young men who had not a push bike to ride or Rs 25 to go on a school trip to Sigiriya are now fabulously wealthy. Cass does not want to list how they demonstrate immense wealth possession now.
One case in the news is Chaminda Sirisena, who seems to be very, very wealthy, wearing a ring that is valued at Rs 10 million, and then losing it to cause severe damnation to its stealer. Goodness! Cass cannot even imagine such a ring. Well, he lost it and 5,000 US $ and Rs 100,000. The suspect is his personal security guard. Having never heard of this brother of the ex Prez and he not being the paddy multimillionaire owning hotels, Cass googled. Here is short reply, “Chaminda Sirisena. Owner Success Lanka Innovative Company, Sri Lanka, 36 followers, 36 connections. (The last two bits of info completely incomprehensible and no desire at all to verify). He sure is comparable to Virgin Airways Branson and other top global entrepreneurs to become so wealthy being a son of a man who served in WWII and was given a small acreage to cultivate paddy in Polonnaruwa. When his brother Maitripala became Prez of Sri Lanka it was with pride the comparison was brought in to the American President who moved from log cabin to the White House.
Hence isn’t our beloved, now degraded Sri Lanka, a land like no other with Midases around?
We now have another maybe thief to worry about. No further news of the poor mother whose life was quashed for the sake of a gold ring, leaving three children motherless and probably destitute. When we were young, we were told very early on that if we lost anything it was more our fault; we were careless and placed temptation to less fortunate persons. The Tamil woman who died after being in remand was such a one who needed extra protection from temptation. To Cass her employer is more to blame for the probable theft and for the tragedy that followed.
Snakes of Sri Lanka
By Ifham Nizam
Snake bites are a serious public health issue in Sri Lanka. It has been estimated that nearly 80,000 snake bites occur here every year.Due to fear and poor knowledge, hundreds of thousands of snakes, mostly non-venomous ones, are killed by humans each year.The state spends more than USD 10 million a year on treating snake bite patients.
According to health sector statistics between 30,000 and 40,000 snake bite patients receive treatment in hospitals annually, says Dr. Anjana Silva, who is Professor in Medical Parasitology, Head/ Department of Parasitology, Faculty of Medicine and Allied Sciences, Rajarata University.
To date, 93 land and 15 sea snake species have been recorded from Sri Lanka. While all 15 sea snakes are venomous, only 20% of the land snakes are venomous or potentially venomous.
The term, ‘venomous snakes’ does not mean they cause a threat to human lives every time they cause a bite. The snakes of highest medical importance are the venomous ones which are common or widespread and cause numerous snakebites, resulting in severe envenoming, disability or death,” says Dr. Silva who is also Adjunct Senior Research Fellow – Monash Venom Group,Department of Pharmacology, Faculty of Medicine, Nursing and Health Sciences, Monash University and Research Associate- South Asian Clinical Toxicology Research Collaboration, Faculty of Medicine, University of Peradeniya.
Only five snakes could be considered to be of the highest medical importance in Sri Lanka: Russell’s viper, Indian krait, Sri Lankan cobra, Merrem’s hump-nosed viper and Saw-scaled viper. All but Merrem’s hump-nosed vipers are covered by Indian Polyvalent antivenom, the only treatment available for snake bites in Sri Lanka.
There are another five snake species with secondary medical importance, which are venomous snakes and capable of causing morbidity, disability or death, but the bites are less frequent due to various reasons (Sri Lankan krait, Highland Hump-nosed viper, Lowland hump-nosed pit viper, Green-pit viper and Beaked sea snake)
The snakes of highest medical importance in Sri Lanka are as follows:
- Russell’s viper (Daboia russelii) (Sinhala: Thith Polanga/ Tamil: Kannadi viriyan)
Medically the most important snake in Sri Lanka. It is found throughout South Asia. It is responsible for about 30% of snake bites in Sri Lanka and also about 70% of deaths due to snake bites in Sri Lanka.
Some 2-5% bites by Russell’s viper are fatal. Widely distributed throughout the country up to the elevations of 1,500m from sea level. Highly abundant in paddy fields and farmlands but also found in dry zone forests and scrub lands. Bites occur more during the beginning and end of the farming seasons in dry zone. It can grow up to 1.3m in length. Most bites are reported during day time.
Over 85% of the bites are at the level of or below the ankle. It is a very aggressive snake when provoked. Spontaneous bleeding due to abnormalities in blood clotting and kidney failure have life-threatening effects.
- The Sri Lankan Russell’s vipers cause mild paralysis as well, which is not life threatening. Indian Polyvalent antivenom covers Russell’s viper envenoming. Deaths could be due to severe internal bleeding and acute renal failure.
- Indian Krait (Bungarus caeruleus) (Sinhala: Thel Karawala/ Maga Maruwa; Tamil: Yettadi virian/ Karuwelan Pambu)
It is distributed in India, Sri Lanka, Nepal, Bangladesh, Pakistan and Afghanistan. It is found across the lowland semi-arid, dry and intermediate zones of Sri Lanka. Almost absent in the wet zone. Usually, a non-offensive snake during the daytime; however, it could be aggressive at night.
Common kraits slither into human settlements at night looking for prey. People who sleep on the ground are prone to their bites.
Most common krait bites do occur at night. Bites are more common during the months of September to December when the north-east monsoon is active. Most hospital admissions of krait bites follow rainfall, even following a shower after several days or months without rain.
Since most bites do occur while the victim is asleep, the site of bite could be in any part of the body.
As bite sites have minimal or no effects, it would be difficult to find an exact bite site in some patients. Bite site usually is painless and without any swelling. Causes paralysis in body muscles which can rapidly lead to life threatening respiratory paralysis (breathing difficulty).
- Sri Lankan Cobra (Naja polyoccelata; Naja naja) Sinhala: Nagaya; Tami: Nalla pambu
Sri Lankan cobra is an endemic species in Sri Lanka. It is common in lowland (<1200m a.s.l), close to human settlements. Cobras are found on plantations and in home gardens, forests, grasslands and paddy fields. It is the only snake with a distinct hood in Sri Lanka.
Hood has a spectacle marking on the dorsal side and has two black spots and the neck usually has three black bands on the ventral side. When alarmed, cobras raise the hood and produce a loud hiss.
Cobra bites could occur below the knee. They are very painful and lead to severe swelling and tissue death around the affected place. Rapidly progressing paralysis could result from bites, sometimes leading to life-threatening respiratory paralysis (breathing difficulty). Deaths could also be due to cardiac arrest due to the venom effects.
- Merrem’s hump-nosed viper (Hypnale hypnale) Sinhala: Polon Thelissa/ Kunakatuwa; Tamil: Kopi viriyan.
Small pit-vipers grow up to 50cm in length. Head is flat and triangular with a pointed and raised snout. They are usually found coiled, they keep the heads at an angle of 45 degrees. Merrem’s Hump-nosed viper (Hypnale hypnale) is the medically most important Hump-nosed viper as it leads to 35-45% of all snake bites in Sri Lanka.
Merrem’s Hump-nosed vipers are very common in home gardens and on plantations and grasslands. Bites often happen during various activities in home gardens and also during farming activities in farmlands in both dry and wet zones. Hands and feet (below the ankle) are mostly bitten. Bites can often lead to local swelling and pain and at times, severe tissue death around the bite site may need surgical removal of dead tissue or even amputations. Rarely, patients could develop mild blood clotting abnormalities and acute kidney failure. Although rare, deaths are reported due to hypnale bites.
- Saw-scaled viper (Echis carinatus), Sinhala: Weli Polanga; Tamil: Surutai Viriyan
This species is widely distributed in South Asia. However, in Sri Lanka, it is restricted to dry coastal regions such as Mannar, Puttalam, Jaffna peninsula and Batticaloa. In Sri Lanka, this snake grows upto 40-50cm. It is a nocturnal snake which is fond of sand dunes close to the beach. It could be found under logs and stones during daytime. Bites are common during January and February.
It is a very aggressive snake. A distinct, white colour ‘bird foot shape’ mark or a ‘diamond shape’ mark could be seen over the head. When alarmed, it makes a hissing sound by rubbing the body scales. Although this snake causes frequent severe envenoming and deaths in other countries, its bites are relatively less severe in Sri Lanka. Bites could lead to mild to moderate swelling and pain on the affected place and blood clotting abnormalities and haemorrhage and rarely it could lead to kidney failure.
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