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Tuesday, 26 July 2016

The chemistry of ice cream

Who doesn’t love ice cream? Especially when the sun is shining! But what is the science that lies behind ice cream making? Have a look at this graphic which takes a look at some of the ingredients that go into ice cream, and the important role they play in creating the finished product.

Graphic: Compound Interest 
Before the development of modern refrigeration, ice cream was a luxury reserved for special occasions. Making it was quite laborious; ice was cut from lakes and ponds during the winter and stored in holes in the ground, or in wood-frame or brick ice houses, insulated by straw. Many farmers and plantation owners, including U.S. Presidents George Washington and Thomas Jefferson, cut and stored ice in the winter for use in the summer. Frederic Tudor of Boston turned ice harvesting and shipping into a big business, cutting ice in New England and shipping it around the world.

Ice cream was made by hand in a large bowl placed inside a tub filled with ice and salt. This was called the pot-freezer method. French confectioners refined the pot-freezer method, making ice cream in a sorbetière (a covered pail with a handle attached to the lid). In the pot-freezer method, the temperature of the ingredients is reduced by the mixture of crushed ice and salt. The salt water is cooled by the ice, and the action of the salt on the ice causes it to (partially) melt, absorbing latent heat and bringing the mixture below the freezing point of pure water. The immersed container can also make better thermal contact with the salty water and ice mixture than it could with ice alone.

The hand-cranked churn, which also uses ice and salt for cooling, replaced the pot-freezer method. The exact origin of the hand-cranked freezer is unknown, but the first U.S. patent for one was #3254 issued to Nancy Johnson on 9 September 1843. The hand-cranked churn produced smoother ice cream than the pot freezer and did it quicker. Many inventors patented improvements on Johnson's design.

In Europe and early America, ice cream was made and sold by small businesses, mostly confectioners and caterers. Jacob Fussell of Baltimore, Maryland was the first to manufacture ice cream on a large scale. Fussell bought fresh dairy products from farmers in York County, Pennsylvania, and sold them in Baltimore. An unstable demand for his dairy products often left him with a surplus of cream, which he made into ice cream. He built his first ice cream factory in Seven Valleys, Pennsylvania, in 1851. Two years later, he moved his factory to Baltimore. Later, he opened factories in several other cities and taught the business to others, who operated their own plants. Mass production reduced the cost of ice cream and added to its popularity.

The development of industrial refrigeration by German engineer Carl von Linde during the 1870s eliminated the need to cut and store natural ice, and, when the continuous-process freezer was perfected in 1926, commercial mass production of ice cream and the birth of the modern ice cream industry was underway.

In modern times, a common method for producing ice cream at home is to use an ice cream maker, an electrical device that churns the ice cream mixture while cooled inside a household freezer. Some more expensive models have an inbuilt freezing element. A newer method is to add liquid nitrogen to the mixture while stirring it using a spoon or spatula for a few seconds; a similar technique, advocated by Heston Blumenthal as ideal for home cooks, is to add dry ice to the mixture while stirring for a few minutes. Some ice cream recipes call for making a custard, folding in whipped cream, and immediately freezing the mixture. Another method is to use a pre-frozen solution of salt and water, which gradually melts as the ice cream freezes.

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Tuesday, 19 July 2016

Air pollution causes wrinkles and premature ageing, new research shows

Air pollution is prematurely ageing the faces of city dwellers by accelerating wrinkles and age spots, according to emerging scientific research.

The effects of toxic fumes on skin are being seen in both western cities, such as London and New York, as well as in more visibly polluted Asian cities and in some cases may be the primary cause of ageing. The pollution is also being linked to worsening skin conditions such as eczema and hives.

The scientific discoveries are now driving the world’s biggest cosmetics companies to search for solutions, including medicine-like compounds that directly block the biological damage. But doctors warn that some common skin care routines, such as scrubs, make the damage from air pollution even worse.

Poisonous air is already known to cause millions of early deaths from lung and heart diseases and has been linked to diabetes and mental health problems. But perhaps its most visible impact, the damage caused to skin, is just beginning to be understood.

“With traffic pollution emerging as the single most toxic substance for skin, the dream of perfect skin is over for those living and working in traffic-polluted areas unless they take steps to protect their skin right now,” said Dr Mervyn Patterson, a cosmetic doctor at Woodford Medical clinics in the UK.

“Unless people do more they will end up wearing the pollution on their faces in 10 years’ time. It is definitely something people now need to take seriously.”

Nitrogen dioxide diffusion tube for air quality monitoring.By Etan J. Tal, via Wikimedia Commons.
Prof Jean Krutmann, director at the Leibniz Research Institute for Environmental Medicine in Germany, said: “UV [damage from the sun] was really the topic in skin protection for the last 20-30 years. Now I think air pollution has the potential to keep us busy for the next few decades.”

Air pollution in urban areas, much of which comes from traffic, includes tiny particles called PMs, nitrogen dioxide (NO2) and chemicals such as polycyclic aromatic hydrocarbons (PAHs). “What is very clear is that PMs are a problem for skin,” said Krutmann, whose work has shown PMs increase age spots and wrinkles.

But one of the his newest studies showed NO2 also increases ageing. They studied people in both Germany and China and discovered that age spots on their cheeks increased by 25% with a relatively small increase in pollution, 10 microgrammes of NO2 per cubic metre. Many parts of the UK have illegally high levels of NO2, with London breaking its annual limit in the first week of 2016, with levels reaching over 200 microgrammes of NO2 per cubic metre.

Krutmann said other factors, such as UV exposure, nutrition and smoking contribute to ageing: “But what we can say is that, at least for the pigment spots on the cheeks, it seems air pollution is the major driver.”

“It is not a problem that is limited to China or India – we have it in Paris, in London, wherever you have larger urban agglomerations you have it,” he said. “In Europe everywhere is so densely populated and the particles are being distributed by the wind, so it is very difficult to escape from the problem.”

The accelerated skin ageing was seen in relatively young people and Patterson said: “If you are seeing these changes in middle age, these are worrying trends.”

Other recent research is summed up in a review paper in the journal Frontiers in Environmental Science, which concluded: “Prolonged or repetitive exposure to high levels of these [air] pollutants may have profound negative effects on the skin.”

Understanding exactly how air pollution causes the skin damage is at an early stage, according to Krutmann: “We are just now dipping into the mechanisms.” But many of the pollutants are known to pass easily through the skin and cause a variety of impacts.

“These agents have a very irritating effect and once they get into the skin, they activate multiple pathways of inflammation,” said Patterson. “Some pathways ignite the melanocytes, which create far too much pigment and end up giving you unwanted sun spots.”

“Other pathways ignite messengers that make blood vessels grow, that’s what results in increased redness and potentially rosacea,” he said. “Also, if you damage skin, it goes into repair mode and excites enzymes which re-adsorb damaged collagen. When you have too much chronic inflammation, these enzymes remove more collagen than your skin can create. This produces skin laxity and that’s where fine lines and wrinkles come in.”

Dr Debra Jaliman, a skin expert based in New York City, says her patients are now worrying about the impact of air pollution on their skin, which she said can cause darkening of the skin and acne-like eruptions, as well as ageing.

“At the moment, there are not many products for prevention [of air pollution damage], however it may be a trend in the coming years as it becomes a much bigger issue,” she said.

Major beauty companies have begun their own research and are launching the first products formulated to battle skin damage from toxic air. Dr Frauke Neuser, senior scientist for Olay, a Procter and Gamble brand, has run studies showing significantly lower skin hydration in people living in polluted areas and lab studies showing that diesel fumes and PMs cause inflammation in skin cells.

Her team then screened for ingredients that could counteract some of the damaging effects. “We found niacinamide - vitamin B3 - to be particularly effective,” she said. “We have recently increased its level in several products by as much as 40%.”

Frauke’s work has also shown direct correlations between spikes in PM air pollution in Beijing and an increase in hospital visits by people with skin conditions including hives. “This indicates that not only skin ageing but also skin health are affected by air pollution,” she said.

L’Oreal, another cosmetics giant, published a medical study in 2015 showing that eczema and hives were more common in people in Mexico exposed to higher levels of air pollution, a conclusion supported by separate research in Canada. “The next step is to understand more deeply the environment-induced damages, in order to develop skin ageing prevention routines and products,” said Dr Steve Shiel, scientific director at L’Oreal.

Clinique, a big makeup brand, has already launched a sonic face cleansing brush it claims better removes pollution. “This [air pollution] is not going to go away. This is not a problem that is easily fixed,” said Janet Pardo at Clinique.

However, researchers are now working on medicine-like compounds that block the damage from air pollution from occurring in the first place. Krutmann’s lab helped Symrise, one of the world’s biggest suppliers of cosmetics ingredients, identify one, though the lab has no commercial stake in the product, which is called SymUrban.

“We found one molecule that can do the job,” he said, and it is now being registered as cosmetic ingredient. “In a few years from now I expect we will see cosmetic products that can specifically protect against skin ageing from air pollution.”

Patterson said it is possible for people to give themselves some protection now. “You don’t have to sit back passively and put up with it. You can take sensible, easy steps that will make a difference.”

“If your skin is really healthy, it is quite a good barrier,” he said, explaining that the top layer is like a roof - flattened cells like tiles separated by protective lipids.

“Certain skin care products are very disruptive to the surface of the skin,” he warned. “So a darling of the industry is retinoids, but these have a very profound negative effect on barrier function. Another darling of the industry is glycolic acid, but it is also very disruptive to the external skin barrier. People think these are good skin care, making the skin look smoother, but they are not helpful for the overall health of the skin barrier.”

Patterson is also dismissive of face scrubs: “The skin is trying its damnedest to make this wonderful defence mechanism and what do women and men do? They scrub the hell out of it. It just doesn’t make sense.” He said products that help repair the skin barrier, by delivering the pre-cursor lipids the cells need, are beneficial, as are ones that tackle inflammation.

“You can also put on a very nice physical shield in the form of good quality mineral makeup,” he said. “That produces an effect like a protective mesh and probably has some trapping effect, protecting against the initial penetration of particles. But you also need always to try to remove that shield in the evening, washing the slate clean every night.”

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Wednesday, 13 July 2016

New antidepressant target discovered

Northwestern Medicine scientists have shown how manipulating a novel target in the brain using gene therapy could lead to new treatments for depression.

The investigators showed decreasing a set of proteins called HCN channels reduced depression-like behavior in mice. If replicated in humans, the findings could inform fresh therapies for millions of patients who do not respond to existing treatments for depression.

"Drugs currently available for treating depression help most patients, but they stop working for some patients and don't work from the get-go for others," said senior author Dr. Dane Chetkovich, a professor of neurology and of physiology at Northwestern University Feinberg School of Medicine and a Northwestern Medicine neurologist. "There is a real need for new therapies to help patients desperate for alternatives to the available therapeutic options."

Drugs currently available for treating depression help most patients, but they don't work for others.
Most existing antidepressants affect mood and emotions by increasing levels of neurotransmitters called monoamines, namely serotonin, dopamine and norepinephrine. But the fact that these drugs are not effective for many patients suggests there are additional mechanisms underlying depression yet to be uncovered that could be targeted with new therapies.

In previous research, Chetkovich's lab and others showed those mechanisms might involve the hippocampus, a region of the brain important for learning, memory and emotional regulation. There, they saw changes to HCN channels, typically involved in controlling the electrical activity of cells in the heart and brain, also played a critical role in behaviors linked to depression.

In the new study, a group of Northwestern scientists led by Chetkovich took steps to translate that insight into a potential gene therapy using mouse models. The scientists surgically injected mice with a nontoxic virus engineered to express a gene that turns off HCN channel function in hippocampus neurons.

"When the HCN channels stopped working, the mice behaved as if they'd been given antidepressant medications," Chetkovich explained.

In contrast, increasing the function of HCN channels removed the antidepressant effect.

To measure depression-like behavior, the scientists measured how long mice would seek to escape an environment before giving up - a test commonly used by the pharmaceutical industry to screen compounds for effectiveness as antidepressants, including medications currently on the market.

"This work not only identifies a totally new treatment target for depression, it provides a detailed molecular description of the structures that need to be manipulated for it to act as an antidepressant and develops viral tools to do so," said Chetkovich, who is also director of Feinberg's Medical Scientist Training Program.

In future research, the scientists are focusing on adapting the viral gene therapy approach to human patients. They also have a grant from the National Institute of Mental Health to find small molecules that could be developed into oral medications to turn off HCN channels in the brain.

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Wednesday, 6 July 2016

EU referendum: UK science wakes up to new future

UK science will have to fight to make sure it is not an after-thought as Britain renegotiates its relationship with the EU, say research leaders.

The science establishment expressed its "disappointment" on Friday with the referendum's outcome.

It had been in the "remain" camp.

How will UK science be affected by Brexit?
The decision to leave the EU now means new structures will have to be put in place if the science sector is to continue to enjoy favourable access to the union's programmes and funding.

Jo Johnson, the minister for universities and science - an "in" supporter - was one of the first to react.

He took to Twitter in the early hours to say: "Big decision. Let's make it work."

Britain's science sector has done increasingly well out of the EU in recent years, receiving €8.8bn in research funding in 2007-2013 versus the €5.4bn it paid in over the same period. And UK-based scientists have won about a fifth of all the grants, in terms of value, from the top-tier programmes run by the European Research Council.

This funding flow-back has been described as being akin to having another Research Council to go with the seven national bodies that presently distribute UK government monies.

To maintain access to the EU stream, Britain will likely now have to get itself some kind of "associated country" status, similar to the positions held by other non-EU countries such as Norway, Switzerland and Israel.

Associated countries pay a GDP membership fee to "join the club", after which, in principle, their scientists can bid for support in the same way as those from full EU member states.

But the exact arrangements will need to be worked out, and are going to depend on wider economic and political factors.

Switzerland, for example, only has "partial" associated status currently because it is not allowing Croatian citizens free access to its labour market.

And having free movement to work collaboratively is central to the way modern science is done.

Scientists for Britain is the group of researchers that has most prominently lobbied for Brexit.

It has argued that the policies of "political union" - and the regulations that flow from Brussels - are not a prerequisite for the UK playing a full role in European scientific collaborations.

The UK can survive and thrive outside full union membership, it contends.

And on Friday, its spokesman Dr Lee Upcraft said he was confident a new settlement would be found to maintain UK involvement in EU programmes and by extension the country's world-leading position in European and global science.

But he also urged the research establishment to hold government to account on national funding.

He echoed a recent complaint from Stephen Hawking, that "we've become reliant on EU funding. We get back a little more than we put in, and associated status will need to address this. But the other thing we need to do, and what UK academia needs to do, is get much better at lobbying government."

EU funding had masked a stagnation in national support, he told BBC News.

Dr Sarah Main from the neutral Campaign for Science and Engineering said there would inevitably be a big uncertainty factor going forward - which comes on top of sector changes already being pushed through parliament in the form of the Higher Education and Research bill (this will bring the seven Research Councils into a single body).

"In the run-up to the referendum, people talked a lot about associated status," she said. "To what extent the EU will make a clear path to enable the UK to obtain associated status and join science programmes back in the EU, I think will be driven by the politics.

"You have to remember that every associated country that people have quoted in the arguments up till now - none was previously a member of the EU that then exited. So, it won't necessarily be straightforward, but it would be welcome because we do want to compete in EU competitive funding streams, and as far as possible influence EU regulations, markets and the conditions for doing science and the training of scientists."

Prof Venki Ramakrishnan, the president of the Royal Society, agreed with Dr Main that ministers must not lose sight of science as they renegotiate Britain's relationship with the EU.

"In the upcoming negotiations, we must make sure that research, which is the bedrock of a sustainable economy, is not short-changed, and the government ensures that the overall funding level of science is maintained," he said in a statement.

Areas that should not be affected directly by the Brexit vote include the big intergovernmental research organisations.

The likes of the European Space agency; the European Southern Observatory, which operates major telescopes; and Cern, which runs the Large Hadron Collider, the largest cryogenic facility in the world at liquid helium temperature, are all separate legal entities to the EU.

However, EU money has increasingly been directed at some of their work. For example, Brussels is now the largest single contributor to Esa's budget, using the agency to procure the Galileo satellite navigation system and the Copernicus/Sentinel Earth observation constellation of satellites.

Britain's science-related companies working in these kinds of fields will want re-assurance that a renegotiated future does not turn into a competitive disadvantage.

Patrick Wood is the managing director of Surrey Satellite Technology Limited, which assembles the navigation payloads for every Galileo spacecraft.

He told BBC News on Friday: "We are days away from submitting the proposal for the next follow-on order, to complete the Galileo constellation, and we will continue to work hard with our supply chain to do this.

"I would look for our UK politicians to unite together to continue to support this flagship European project containing key UK technology, knowhow and to help protect jobs here in the UK."

Likewise, the chair of the House of Commons Science and Technology committee, Nicola Blackwood MP, wanted to highlight the care now needed to ensure the commercial science sector was properly supported.

"My committee's recent report into EU regulation of the life sciences pointed out that this sector alone comprises almost 5,000 companies employing 200,000 people in the UK, generating an annual turnover of £60bn. The Science and Technology Committee will want, in the coming weeks and months, to look at the consequences of this vote for British science," she said.

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