Have scientists worked out why hot water freezes faster than cold water?


Scientists claim to have solved why hot water appears to freeze faster than cold water

It is a phenomenon that has baffled the world’s brightest minds since the time of Aristotle.

Now a team of physicists believe they may have solved the centuries old mystery of why hot water freezes faster than cold water.

Known as the Mpemba effect, water behaves unlike most other liquids by freezing into a solid more rapidly from a heated state than from room temperature.

Scientists have suggested dozens of theories for why this may occur, but none have been able to satisfactorily explain this strange physical property.

A team of physicists at the Nanyang Technological University in Singapore have now published what they believe may be the solution.

Each water molecule is bound to its neighbour through a highly charged electromagnetic bond known as a “hydrogen bond”.

It is this that produces surface tension in water and also gives it a higher than expected boiling point compared to other liquids.

However, Dr Sun Changqing and Dr Xi Zhang from Nanyang Technological University, argue this also determines the way water molecules store and release energy.

They argue that the rate at which energy is released varies with the initial state of the water and so calculate that hot water is able to release energy faster when it is placed into a freezer.

Dr Changqing said: “The processes and the rate of energy release from water vary intrinsically with the initial energy state of the sources.”

The Mpemba effect is named after a Tanzanian student called Erasto Mpemba, who observed that hot ice cream mix froze before the cold mix.

Together with a physics professor at University College at Dar es Salaam, he published a paper in 1969 that showed equal volumes of boiling water and cold in similar containers would freeze at different times, with the hot water freezing first.

Similar observations have been described in the past, however, by Aristotle, Francis Bacon and Rene Descartes.

The effect can also have some real world implications, such as whether to use boiling water to defrost the windscreen of your car on a winters day and whether hot water pipes are more prone to freezing than cold ones.

Some people deny that the effect exists at all and is in fact an artefact of experimental procedure, but others claim to have shown it using carefully controlled experiments.

There are a number of theories for might cause this, including that evaporation of hot water means there is less water to freeze.

Another theory suggests that dissolved gasses in the water are released in hot water and so make it more viscous.

Last year the Royal Society of Chemistry offered a £1,000 prize to anyone who could explain how the Mpemba effect worked.

Nikola Bregovic, a chemistry research assistant at the University of Zagreb, was announced as the winner for the prize earlier this year.

He conducted experiments using beakers of water in his laboratory and his resulting paper suggested that the effect of convection was probably responsible.

He said that convection currents set up in the warm water cause it to cool more rapidly.

However, Dr Changqing and Dr Zhang have attempted to explain the effect further by examining the process at a molecular level.

Last week they published a paper in the journal Scientific Reportsshowing how water molecules arrange themselves when forming ice

They also published a paper on arXiv Chemical Physics that explained the Mpemba effect.

They say the interaction between the hydrogen bonds and the stronger bonds that hold the hydrogen and oxygen atoms in each molecule together, known as covalent bonds, is what causes the effect.

Scientists in Singapore claim to have worked out why hot water freezes faster than cold water

Normally when a liquid is heated, the covalent bonds between atoms stretch and store energy.

The scientists argue that in water, the hydrogen bonds produce an unusual effect that causes the covalent bonds to shorten and store energy when heated.

This they say leads to the bonds to release their energy in an exponential way compared to the initial amount stored when they are cooled in a freezer.

So hot water will lose more energy faster than cool water.

Dr Changqing said: “Heating stores energy by shortening and stiffening the H-O covalent bond.

“Cooling in a refrigerator, the H-O bond releases its energy at a rate that depends exponentially on the initially stored energy, and therefore, Mpemba effect happens.”

The Royal Society of Chemistry received more than 22,000 responses to its call for a solution to the Mpemba effect and it is still receiving theories despite the competition closing a year ago.

Mr Bregovic, who was judged to have developed the best solution by a panel of experts a conference at Imperial College London last year, said: “This small simple molecule amazes and intrigues us with its magic.”

Aeneas Wiener, from Imperial College who helped to judge the competition, added: “The new paper demonstrates that even though a phenomenon seems simple, delving deeper reveals even more complexity – and that is certainly worth looking at.

“We hope it’ll inspire young people to pursue scientific studies.”

Dr Denis Osborne, a lecturer at University College in Dar es Salaam who published the paper with Mr Mpemba on the effect they had observed, said: “Several different mechanisms may cause or contribute to an Mpemba effect.

“What the authors describe as a property of H-O bonding may be one of these.”

Cancer Is A Purely Man-Made Disease, Researchers Confirm


Researchers from the University Of Manchester, United Kingdom, have concluded that cancer is a purely man-made disease, fueled by the excesses of modern life. Scientists spent a great deal of time studying mummies, fossils and classical literature before reaching this conclusion. In the study of Egyptian mummies, for example, scientists found no signs of cancer in many of them—with the exception of one isolated case.

Slivers of tissue from hundreds of Egyptian mummies were rehydrated and placed under the microscope. They found only one case of cancer in the mummies examined. In the past, some scientists have argued that the ancient Egyptians did not live long enough to develop cancer. To dismiss this weak argument, the researchers pointed out that other age-related disease, such as hardening of the arteries and brittle bones, occurred during this time. The journal Nature Reviews Cancer reports that fossil evidence of cancer is not solid, with scientific literature providing a few dozen, mostly disputed, examples in animal fossils. Even the study of thousands of Neanderthal bones has provided only one example of a possible cancer. Evidence of cancer in ancient Egyptian texts is also tenuous, with cancer-like problems more likely being caused by leprosy or even varicose veins.

It is said the ancient Greeks were probably the first to define cancer as a specific disease, and to distinguish between benign and malignant tumors. The 17th century provides the first descriptions of operations for breast and other cancers. However, the first reports in scientific literature of distinctive tumors only occurred in the past 200 years. Nasal cancer in snuff users appeared in 1761. Scrotal cancer in chimney sweeps was also discovered in 1775. Lead researcher of this study, Michael Zimmerman said there should have been plenty of cancer-related evidence available in ancient societies because they lacked effective healthcare. “In an ancient society lacking surgical intervention, evidence of cancer should remain in all cases.

The virtual absence of malignancies in mummies must be interpreted as indicating their rarity in antiquity, indicating that cancer-causing factors are limited to societies affected by modern industrialization,” Zimmerman said. Professor Rosalie David, who also played a key role in the analysis of the possible reference to the disease in classical literature, fossil records and mummified bodies, said: “In industrialized societies, cancer is second only to cardiovascular disease as a cause of death. But in ancient times, it was extremely rare. There is nothing in the natural environment that can cause cancer. So it has to be a man-made disease, down to pollution and changes to our diet and lifestyle.

The important thing about our study is that it gives a historical perspective to this disease. We can make very clear statements on the cancer rates in societies because we have a full overview. We have looked at millennia, not one hundred years, and have masses of data. Yet again extensive ancient Egyptian data, along with other data from across the millennia, has given modern society a clear message – cancer is man-made and something that we can and should address.” Scientists recommend a healthy diet, regular physical activity and maintenance of a healthy weight. These 3 lifestyle choices are believed to be able to prevent about a third of the most common cancers.

Sleep loss detrimental to blood vessels


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Blood vessel with an erythrocyte (red blood cell, E) within its lumen, endothelial cells forming its tunica intima (inner layer), and pericytes forming its tunica adventitia (outer layer) 

Lack of sleep has previously been found to impact the activation of the immune system, inflammation, carbohydrate metabolism and the hormones that regulate appetite. Now University of Helsinki researchers have found that sleep loss also influences cholesterol metabolism.

The study examined the impact of cumulative sleep deprivation on cholesterol metabolism in terms of both gene expression and blood lipoprotein levels. With state-of-the-art methods, a small blood sample can simultaneously yield information about the activation of all genes as well as the amounts of hundreds of different metabolites. This means it is possible to seek new regulating factors and metabolic pathways which participate in a particular function of the body.

“In this case, we examined what changes sleep loss caused to the functions of the body and which of these changes could be partially responsible for the elevated risk for illness,” explains Vilma Aho, researcher from the Sleep Team Helsinki research group.

The study established that the genes which participate in the regulation of cholesterol transport are less active in persons suffering from sleep loss than with those getting sufficient sleep. This was found both in the laboratory-induced sleep loss experiment and on the population level.

While analysing the different metabolites, the researchers found that in the population-level data, persons suffering from sleep loss had fewer high-density HDL lipoproteins, commonly known as the good cholesterol transport proteins, than persons who slept sufficiently.

Together with other risk factors, these results help explain the higher risk of cardiovascular disease observed in sleep-deprived people and help understand the mechanisms through which lack of sleep increases this risk.

“It is particularly interesting that these factors contributing to the onset of atherosclerosis, that is to say, inflammatory reactions and changes to cholesterol metabolism, were found both in the experimental study and in the epidemiological data,” Aho says.

The results highlight the health impact of good sleep. The researchers emphasise that health education should focus on the significance of good, sufficient sleep in preventing common diseases, in addition to healthy food and exercise. Even a small reduction in illnesses, or even postponing the onset of an illness, would result in significant cost savings for society at large.

 

Children who snack on sweets after meals more likely to be overweight, study says .


Image: Children who snack on sweets after meals more likely to be overweight, study says (Audio)

Compared to toddlers who crave salty foods, children who mindlessly snack on cookies and cake may be more likely to wind up overweight, a U.S. study suggests.

To study what’s known as ‘eating in the absence of hunger’, researchers tracked how many sweet and salty snacks children ate just after finishing a full meal.

Children who ate the most sweets after the meal threw the biggest tantrums when the treats were taken away. These children had greater odds of gaining excess weight than kids who grazed on salty foods or didn’t put up a fuss when their snack was removed, the study found.

Can we hypercharge vaccines? Tapping a chemical we already make could enhance T-cell production


Vaccine
Researchers at Boston Children’s Hospital report that a fatty chemical naturally found in damaged tissues can induce an unexpected kind of immune response, causing immune cells to go into a “hyperactive” state that is highly effective at rallying infection-fighting T-cells. The findings, published online by Science on April 21, could enhance vaccines and make them much more effective.

The researchers, led by Jonathan Kagan, PhD, got a five times greater adaptive in mice when using the chemical, called oxPAPC. They believe that oxPAPC or a related synthetic compound could be used to help immunize people against a wide range of infections. “We think this could be a general means to increase response to any type of vaccine,” says Kagan, also an associate professor at Harvard Medical School.

oxPAPC targets only —sentinels that circulate around the body searching for microbes and activating T-cells to destroy the invaders. Previously, it was thought that dendritic cells (also commonly known as antigen-presenting cells) have just two : an inactive state, in which they can search for microbes, and an active state, in which they have encountered a microbe and gain the ability to activate T-cells.

“We identified a naturally-occurring molecule that creates a heightened, ‘hyperactive’ state of dendritic cell activation,” says Kagan. “These hyperactive cells live for a long time and are the best activators of T-cells that we know of, so this could be a very useful tool in vaccine development.”

In particular, when they gave oxPAPC to mice, they saw strong activation of memory T-cells. Memory T-cells respond more effectively to invaders than other kinds of T-cells, but are not efficiently elicited by ordinary activated dendritic cells.

Kagan’s team further showed that hyperactivated dendritic cells make a critical protein, IL-1ß, that triggers memory T-cell production. Dead dendritic cells also release IL-1ß, but only for a short period of time. Hyperactivated dendritic cells produce IL-1ß for longer times, which likely explains why they are such effective stimulators of memory T-cells.

Finally, the researchers found that oxPAPC’s key target is an enzyme called caspase-11. When activated by other molecules, caspase-11 triggers cell death and inflammation. But when activated by oxPAPC, the enzyme promotes hyperactivation of dendritic cells.

“These discoveries highlight that dendritic and caspase-11 can have more than one activation state, which was never before known,” says Kagan.

Kagan and Boston Children’s Hospital’s Technology and Innovation Development Office (TIDO), have filed for a patent on this work and are seeking investor interest so they can move oxPAPC or a similar compound toward a clinical trial.

Losing weight after pregnancy.


Post birth, many woman desire to return to their pre-pregnancy size weight. This infographic provides tips and information to enable young mothers to achieve their goal. Dieting is not really the way to do it but following these guidelines will certainly help. A combination of healthy diet plus some exercise will help to lose weight after having a baby.

11 daily habits of self-made billionaires anyone can adopt.


 

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If you want to get rich, start by studying the people who have already done so.

“The only person who can teach you how to think like a millionaire is a millionaire,” writes Steve Siebold in his book, “How Rich People Think.”

The same could be said about billionaires.

Below, we’ve rounded up 11 habits of self-made billionaires. You may notice that none of them require dramatic life changes – a few tweaks here and there to your daily routine could result in huge gains.

http://m.businessinsider.in/11-daily-habits-of-self-made-billionaires-anyone-can-adopt/articleshow/51932895.cms

Scientists Have Created A Fuel Cell That Runs On Urine — Yep, Urine


With planet Earth facing a barrage of environmental threats — namely, fossil fuel depletion, pollution and climate change — clean, renewable energy is critically important.

And while emerging energy sources like solar, wind and hydroelectricity seem promising, they may soon be joined by the unlikeliest of renewable resources: urine.

In a new paper, a team of researchers at England’s University of Bath announced they developed a low-cost, pee-powered fuel cell capable of running electronic devices, including cell phones.

Dr. Mirella Di Lorenzo, a lecturer in the university’s department of chemical engineering and an author of the study, said the ability to harness the power of human waste could revolutionize electricity generation.

“Microbial fuel cells can play an important role in addressing the triple challenge of finding solutions that support secure, affordable and environmentally sensitive energy, known as the ‘energy trilemma,’” Di Lorenzo said in a statement. “There is no single solution to this ‘energy trilemma’ apart from taking full advantage of available indigenous resources, which include urine.”

UNIVERSITY OF BATH
Dr. Mirella Di Lorenzo, a lecturer in the University of Bath’s Department of Chemical Engineering, holds a pee-powered fuel cell.

The device is roughly the size of a U.S. quarter, costs between $1.50 and $3 to make, and “uses natural biological processes of ‘electric’ bacteria to turn organic matter, such as urine, into electricity,” according to a release. As urine passes through the fuel cell, it reacts with the bacteria, generating electricity that researchers say can either directly power an electronic device or be stored for later use.

Researchers said a single cell is capable of generating 2 watts per cubic meter, enough to power a cell phone for an unspecified amount of time, but the power output could be significantly increased by stacking multiple cells together.

While recognizing that the output of a single cell “is not comparable with other alternative technologies such as hydrogen or solar fuel cells,” researchers said the urine-powered fuel cells come with their own set of unique advantages, specifically small size and manufacturing cost.

Lead author Jon Chouler said he’s particularly excited about the cell’s potential in poor and developing countries.

“To have created technology that can potentially transform the lives of poor people who don’t have access to, or cannot afford electricity, is an exciting prospect,” Chouler said in a statement. “I hope this will enable those in need to enjoy a better quality of life as a result of our research.”

Surprisingly, this is not the first time scientists have pondered — or even proven — pee’s potential.

In 2011, Ohio University’s Gerardine Botte invented a way to use urine to create a hydrogen fuel. And a group of teenagers in Africa successfully developed a generator that runs on the bodily fluid.

So stay plenty hydrated, Earthlings, because apparently our bodies produce renewable energy daily.

10 Science Experiments That Had The Potential To Wipe Out Humanity


In the attempt to unfold the secrets of life on Earth, its existence and many more things, man has done a lot of experimentation. However, during these experiments and activities often done to decode the mystery of earth, scientists have also risked humankind.

Man has always wandered into the darkness to explore the abyss and return with knowledge that may help them to grow and expand their horizon. But these experiments and calculations have always involved several dangers that have sometimes risked to entire mankind. From exploding nuclear bombs in outer space to trying to re-create the big bang, the human race has come pretty close to destroying itself on many occasions… all in the name of science.

History is full of strange experiments that people predicted might bring about the end of the human race… and in some cases; they might actually have had a point.

There have been miscalculations and calculated risks taken with the knowledge of the dangers with the hope of achieving a positive outcome. Whether it was the largest particle collider setup near Geneva or activities done under SETI, all these process to find human’s existence or alien, these activities have always raised a big risk on human and sometime even on earth.

Here are 10 scientific experiments that people believed, rightly or wrongly, had the potential to wipe out humanity.

http://www.speakingtree.in/blog/10-science-experiments-that-had-the-potential-to-wipe-out-humanity

Ultrasonic Signals Transmit Data Through Meat at HD Video Quality.


Researchers achieved data rates as high as 30 megabits per second through this pork loin suspended between two transducers.

Modern medical implants are hobbled by slow download speeds. Most medical devices transmit data over radio frequencies at the relatively glacial pace of fewer than 50 kilobytes per second. At that rate, it can take ages for physicians to transfer data or reprogram devices.

New evidence suggests ultrasonic signals could speed up that process. Researchers who achieved higher data rates in one early test say that these signals may eventually enable doctors to live stream high-quality video from inside of a patient.

A team led by Andrew Singer, an electrical engineer at the University of Illinois at Urbana Champaign, found that they could use ultrasonic signals totransfer data through meat at speeds up to 30 megabits per second. That’s the highest ever recorded data rate for signals transmitted through animal tissue, Singer says. For comparison, streaming Netflix in Ultra HD requires 25 megabits per second.

Most implants installed today broadcast on radio frequencies. But those signals must remain below a maximum bandwidth of 300 kilohertz. More powerful signals might cause the resulting electromagnetic waves to interfere with nearby devices. They could also harm patients, since the body absorbs some waves as the signals pass through. Or as Singer puts it, “We are a bag of salt water, and electromagnetic waves heat up salt water.”

In addition to being dangerous, this absorption also makes data transfer quite inefficient. Singer wanted to use ultrasonic signals to transmit data at higher rates and keep more of it intact along the way.

Before he could begin his experiment, Singer had to pick up some pork loin and beef liver from County Market in Champaign, Ill. He threw some pig knuckles in the shopping bag, too because he thought it might be neat to try to transmit wireless signals through bone and gristle.

Back at his lab, colleagues rejected the pig knuckles. But the remaining slabs were carefully strung, one at a time, between two 5-megahertz transducers in a tank filled with water. One transducer converted binary digital data to ultrasonic signals that were transmitted through the meat. Its twin measured the resulting data rates.

Singer was happy to see that, in addition to the signal traveling fast, most of the original data arrived intact, with little lost during its journey through the meat.  “We were a little bit surprised that the meat really did not provide much in terms of additional dispersion or attenuation,” Singer says. “The signals coupled extremely well and we had almost the entire bandwidth available to us for data transmission.”

Jeremy Dahl, a radiologist at Stanford University who focuses on ultrasonic devices, points out that the transducers in Singer’s study were positioned only 5.86 centimeters apart, with the meat in the middle. Therefore, it’s not clear that medical devices embedded deep in the body could achieve similar rates while transmitting to, for example, a physician’s kiosk across the room.

And since they didn’t test the pig knuckles, Singer’s group still doesn’t know how ultrasonic signals will stack up as a method of data transmission when when signals have to travel through bone or skin.

Another potential issue is that ultrasonic signals travel in a beam instead of broadcasting in all directions at once. A physician would have to know how a device is oriented within a patient’s body in order to catch the signal it emits.

“If you’re trying to receive from a different location from where that beam is directed, you’re not going to receive any signal,” Dahl says. Radio frequency is omnidirectional, so an external device can capture it from any direction.

Next, Singer hopes to pursue animal studies. In the future, he thinks higher data rates achieved through ultrasonic signals could allow physicians to ask a patient to swallow a camera and watch a live stream as it passes through the digestive tract.

Or, it might enable practical functions that have so far eluded the medical device industry, such as making software upgrades to devices that are already in place. “At today’s rates for communicating with implantable devices, you’d never even consider the possibility to change the software on these things,” Singer says.