Researchers from Purdue University have developed a new white paint that can reflect over 95 percent of sunlight, which can cool the surface even lower than the surrounding temperature. Painted on a building, the new paint could help cut cooling costs and energy use.

Many different reflective cooling paints have been developed over the years, but they all have their drawbacks. For the new study, the Purdue researchers developed a new method—using calcium carbonate (碳酸钙) fillers, which are much richer, cheaper, and absorb less ultraviolet (紫外线的) light. And the new reflective cooling paint can give off more sunlight—reflecting 95.5 percent of the light that strikes it. That’s better than many of the other paints in development, which manage between 80 and 90 percent, although it falls short of the record holder—the Teflon coating, which reflects 98 percent of light.

The team tested the new coating outdoors over two days, and showed that under direct sunlight it remained 1.7℃ below the surrounding temperature. In another set of tests, the researchers painted some parts of a pattern with the new paint, and others with a regular white paint of the same thickness. Using a special camera, they could see the pattern clearly, thanks to the difference in temperature between the two materials.

The team says that the new paint could not only help cool buildings, but prevent outdoor electrical systems from overheating. But to ensure that it is commercially practicable, the researchers next plan to investigate how well it lasts out in the environment.

“The cost of our paint may be comparable to other commercial paints or even lower than them,” says Xiulin Ruan, an author of the study. “The key is to ensure the reliability of the paint so that it is workable in long-term outdoor applications.”

It takes a certain quickness to pick a strawberry or a salad. While crops （农作物）like wheat and potatoes have been harvested by machine for decades, many fruits and vegetables have proved resistant （有抵抗的）to automation. They are too easily damaged, or too hard for heavy farm machinery to locate.

But recently, technological developments and advances in machine learning have led to successful trying of more sensitive and skillful robots, which use cameras and artificial intelligence （Al） to locate ripe fruit and handle it carefully and exactly.

Developed by engineers at the University of Cambridge, the Vegebot is the first robot that can identify and harvest iceberg lettuce - bringing hope to farmers that one of the most demanding crops for human pickers could finally be automated.

First, a camera scans （扫描）the lettuce and, with the help of a machine learning calculation trained on more than a thousand lettuce images, decides if it is ready for harvest. Then a second camera guides the picking cage on top of the plant without breaking it. Sensors feel when it is in the right position, and pressed air drives a blade through the stalk （柄）at a high force to get a clean cut.

Its success rate is high, with 91% of the crop accurately classified, according to a study published in July. But the robot is still much slower than humans, taking 31 seconds on average to pick one lettuce. Researchers say this could easily be sped up by using lighter materials.

Such adjustments would need to be made if the robot was used commercially （商业地）. "Our goal was to prove you can do it, and we've done it,” Simon Birrell, co-author of the study, tells CNN Business. "Now it depends on somebody taking the baton （指挥棒）and running forward," he says.

With the summer heat becoming increasingly unbearable over the years due to climate change, the cooling load in the summertime has also been on the rise. Insulation (隔热) is currently the main solution for blocking heat from entering a building, but by applying an additional material that can delay heat penetration (渗透), it can prevent the indoor temperature from rising and in turn lower the cooling load of the building.

A research team in Korea has developed a new material for building walls that can help reduce the penetration of heat from the outside. The team directed by Dr. Sarng Woo Karng from KIST revealed that they have successfully done it through building walls by applying a phase change material (PCM).One of the most common types is paraffin oil, which is used to make candles.

A solid PCM absorbs heat as it transforms into a liquid phase, so by using a case to hold it when it is in a liquid phase without causing any leakage, it is possible to apply them to a building wall to block heat from entering inside.

The problem, however, is that the PCM turns into liquid starting from the outermost layer, and the parts that are hot move upward, while the parts that are still relatively cool move downward. Thus, while the upper part may have completely melted, the lower part will have not, and as a result, heat will penetrate into the building through the area where the PCM is in a liquid phase. In the end, the PCM becomes ineffective in controlling the indoor temperature and is rendered useless.

Dr. Karng’s team addressed the non-uniform phase change with bubble injections .Injecting bubbles into the bottom part of the PCM enabled uniform circulation (流动) of the PCM in a liquid phase. Dr.Karng said, “We expect that the insulating wall using the PCM bubble generator used in this study will contribute to reducing the amount of energy used to heat or cool a building. Insulation techniques using the PCM help reduce heat penetration, in combination with the building insulating material, and it can also be used as the outer walls of zero-energy buildings.