Which countries are the central nodes of the global trade network? While China is currently the world’s largest trading partner, this hasn’t always been the case.

This series of graphics by Anders Sundell outlines the history of the world’s biggest trade hubs, showing how the landscape has evolved since 1960. Using netgraphs, each visual connects countries to their primary trading partner, using data that includes both imports and exports.

In people who had been infected with SARs-CoV-2 and were then vaccinated, the outcome was completely different: All the vaccines provided a major immunological boost against re-infection, and the differences between the mRNA shots and the other ones "began to blur," says John Moore, a virologist at Weill Cornell Medicine in New York who was not involved in the study.

Of the five vaccines tested, four produced nearly identical immune reactions. This group included Pfizer's mRNA shot as well a shot made by AstraZeneca, the Sputnik V shot made by the Gamaleya Research Institute of Epidemiology and Microbiology in Russia, and one from Cansino, a Chinese company. A fifth vaccine, CoronaVac, made by Sinovac Biotech in China, was the worst performer, though still protective to some degree. //

The study's point that vaccinating after a case of COVID provides protection against future infections is supported by a newly-published Israeli study. Researchers found that unvaccinated individuals who had recovered from COVID and were then given the Pfizer vaccine had significantly lowered reinfection risks after getting a Pfizer vaccine.

Summing up the two findings, Moore says "The Israeli paper tells you that vaccinating convalescent people has real-world benefits and the Rockefeller paper tells you the vaccine you use [either mRNA or non-mRNA] is inconsequential — you get the benefits from each."

Many attempts at solar desalination systems rely on some kind of wick to draw the saline water through the device, but these wicks are vulnerable to salt accumulation and relatively difficult to clean. The team focused on developing a wick-free system instead.

The result is a layered system, with dark material at the top to absorb the sun’s heat, then a thin layer of water above a perforated layer of material, sitting atop a deep reservoir of the salty water such as a tank or a pond. After careful calculations and experiments, the researchers determined the optimal size for the holes drilled through the perforated material, which in their tests was made of polyurethane. At 2.5 millimeters across, these holes can be easily made using commonly available waterjets.

The holes are large enough to allow for a natural convective circulation between the warmer upper layer of water and the colder reservoir below. That circulation naturally draws the salt from the thin layer above down into the much larger body of water below, where it becomes well-diluted and no longer a problem. “It allows us to achieve high performance and yet also prevent this salt accumulation,” says Wang, who is the Ford Professor of Engineering and head of the Department of Mechanical Engineering.

Li says that the advantages of this system are “both the high performance and the reliable operation, especially under extreme conditions, where we can actually work with near-saturation saline water. And that means it’s also very useful for wastewater treatment.”

With the attention of the world focused on events in Ukraine, one of the questions people are asking is about the country’s nuclear power industry. Here is a brief overview. //

Ukraine is heavily dependent on nuclear energy, with 15 reactors generating about half of its electricity. All its current reactors are Russian-designed VVER types. //

As of mid-2021, six of Ukraine’s 15 reactors were operating using fuel manufactured by Westinghouse, fabricated at its plant in Västerås in Sweden. //

"In the event of loss of the external power supply at the nuclear power plant, the autonomous power supply system starts working by means of powerful diesel generators. Ukrainian nuclear power plants are ready for such a mode of operation: the stock of diesel fuel located at nuclear power plants significantly exceeds the established standards. //

He added that two years' worth of nuclear fuel had been stockpiled in case of interruption of supply.