【推荐1】Most air conditioners and fridges rely on contracting and expanding a liquid to either absorb or release large quantities of heat. While these systems are relatively cheap and simple to produce, they aren’t very efficient and require lots of energy. Besides, many of the coolants used are environmentally harmful.

Now, Emmanuel Defay at the Luxembourg Institute of Science and Technology and his colleagues have developed a coolant-free refrigeration device made from the metals lead, scandium (钪) and tantalum (钼). It can reach maximum efficiencies of more than 60%, almost double that of typical single-room air conditioning units. The technology is based on a principle called electrocaloric cooling, in which an electric field applied across a material changes the direction of electric charges, causing a temporary increase in temperature and a succeeding decrease when the electric field is removed.

To make their cooling system, Defay and his colleagues piled up eight strips of the material known as lead scandium tantalate, which is electrocaloric, on top of one another and dipped them in a heat-carrying liquid, silicone oil. When an electric field is switched on and the strips heat up, the liquid moves to the right, and when it cools down, it moves to the left, creating permanent regions of hot and cold of about 20℃difference. These regions can be used as hot and cold reservoirs from which the oil can be circulated through pipes to cool or heat rooms or objects as desired.

“Although the efficiency of the device is theoretically 67%, the efficiency of the current design is around 12%. This could be improved if a better conductor of heat than the lead scandium tantalate were found,” said Defay.

“A highest performance has been achieved by combining known elements,” said NeilMathur at the University of Cambridge. However, he added, the team only looked at the cooling power of the pile of metal strips themselves, while it would be interesting to see how the entire device performs together.

【推荐2】There's little more frustrating than being told to smile when you're feeling miserable, but new research published in the journal Experimental Psychology has found that faking（装出）a smile can act on the parts of our brain linked to mood, improving our outlook.

Led by researchers at the University of South Australia, the study confirmed that forcing a smile can essentially trick the mind into receiving the facial expressions and body language of others more positively, which in turn boosts our own mood. I guess that the “fake it till you make it” approach can hold more water than we realized.

In the experiment, the researchers gathered a group of participants and asked them to place a pen between their teeth. If you try doing this yourself now, you'll notice holding a pen forces your face into a smile. They then asked the participants to evaluate the facial expression and movements of other people, sometimes with the pen in their mouth and sometimes without.

The results showed that the pen-in-mouth people viewed the facial expressions and movements of others in a more positive light than those with no pen. By forcing the face into a smile, the experiment was able to improve the outlook of participants regardless of their mental state. The findings showed that smiling not only changes how we see facial expressions but also how we read body expressions, with both generating more positive emotions within us.

“When your muscles say you're happy, you're more likely to see the world around you in a positive way,” said Dr. Marmolejo-Ramos, lead researcher on the study. "In our research we found that when you forcefully practice smiling, it stimulates the emotional center of the brain to encourage an emotionally positive state."

For mental health, this has interesting meanings. If we can trick the brain into treating stimuli（刺激）as "happy", then we can potentially use this mechanism to help improve mental health. Well, I guess there's only one thing to do then…

【推荐1】Benefits (好处) of Exercising Outdoors

Compared with traditional indoor workouts, outdoor exercise — sometimes called green exercise — provides more benefits. Here are several benefits of doing your workouts outdoors.

    1     The first, and perhaps most important benefit, is that being in nature increases feelings of well-being and life satisfaction. In fact, simply being outside and breathing fresh air can make you light-hearted. Research shows that being in nature, also called forest bathing, reduces stress and increases relaxation, and you'll see greater levels of joy in your life.

It's free. There are many benefits of working with an exercise professional in a gym or fitness facility, but doing outdoor exercise is a great way to save money.     2     For example, you can choose some common activities such as biking jogging, hiking or playing tennis.

It's social and increases responsibility.     3     You can also go out with your partner or children at the park for some family fun. If so, you've added two main parts to your exercise program: social support and responsibility.     4    

It doesn't take a lot of time to see the benefits. It's important to note that the benefits of outdoor exercise start at 120 minutes per week.     5     You can have a 25-minute walk every workday or a two-hour hike on weekends. More time spent exercising outside beyond those 120 minutes will have more benefits, but that's a great goal for most people.

【推荐2】How much physical activity do you do in a week? Are you getting enough exercise? Adults who do exercise for just 150 minutes a week can reduce their risk of serious illness by 50%. Regular exercise reduces the risk of early death by 30%.     1     Today, we are much less active than in the past. In fact many adults spend seven hours or more on a chair each day.   

    2     It means that we need to do something extra to burn more calories and use up all our energy. Adults need to do two and a half hours of moderate exercise per week. In addition, you should do exercise to strengthen muscles twice a week.

    3     Team sports such as football, rugby or cricket can be cheap because all the players share the cost of the pitch. Joining a sports club is usually a cheap way of getting exercise and can be very sociable, too.   

Alternatively, if you don't want to spend any money at all, go for a run. The only equipment needed for this is a pair of trainers     4     Go to the park. Try getting a group of friends or family together and have a game of football there.

Although adults should do two and a half hours of exercise a week, you don't have to do it all at one time.     5     If you do ten minutes before work ten minutes during your lunch break and ten minutes after work, five days a week, you've achieved the target! There are many ways of getting fit and we should all recognize the value of doing this, because we will live longer and be more healthy.

【推荐3】Yoga is a discipline I’ve long been a fan of, and I practise sun salutations (拜日式) several times a week. I know it does me good and now I have to add another benefit — it could be a life saver for people recovering from a heart attack.

I’m not at all surprised to learn that an Indian study of almost 2,500 people recovering from heart surgery found breathing exercises and stretching boosted circulation and strengthened the heart Furthermore, the researchers claimed a three-month programme of yoga while recovering from surgery after a heart attack resulted in a lower risk of being bit by another.

Better sill, people who did a daily hour of breathing exercises and gentle movement were about 16% less likely to die over the next five years. Why? Tests showed participants’ hearts were pumping blood around the body more efficiently.

Lead researcher Professor Naresh Sen, from Jaipur, said, “Patients undertook three months of a Dew daily one-hour programme specifically designed for patients who have heart diseases, combining yoga with meditation in the morning, and a pattern of breathing exercises, comprising slow and fast breathing elements in the evening. Yoga and breathing exercises may reduce metabolic (新陈代谢的) stress, reduce oxygen demand and prevent ventricular remodelling (damage to the heart).”

Yoga performed well given tat the trial involved patients who bad suffered the most serious type of heart attack, where one of the major arteries is blocked. All bad undergone surgery to widen the vessels, using a stent (支架) to allow blood to flow more freely. Half the patients were then put on a three-month programme of yoga Over the next five years, the patients in the yoga group were 16% less likely to die. There was an unexpected bonus too, heart performance was improved, with an 1I% boost to its ability to pump blood round the body. Those who didn’t do yoga saw an increase of only 4%.