Researchers at the University of Birmingham, U.K., and Duke University, U.S., have described the exceptional strength and toughness of novel polymers made from sugars, and the chemistry underpinning their characteristics, in a study published in Angew Chemie.

The study examined two polymers based on isosorbide and isomannide that were produced by a recently disclosed method that uses sugars as a starting point for synthesis. Both polymers have superior properties to conventional thermoplastic elastomers, and in addition, are degradable and mechanically recyclable.

In a key finding, the researchers discovered that the polymer made from isosorbide displayed superior elastic recovery and toughness which was shown to be a result of the stereochemistry of the sugar groups in the materials.

Using supercomputer simulations and other experimental techniques, the researchers showed that the difference in elastic recovery results from the way that the sugar stereochemistry directs the network of hydrogen bonds between and within the long-chain molecules.

The researchers concluded that both polymers have high optical clarity, exceptional mechanical strength, and extensibility, but the isosorbide-based polymer has superior toughness, due to its higher elasticity.

Professor Andrew Dove, from Birmingham’s School of Chemistry, commented, who led the research team, commented: “The long-term impacts of modern polymers on the environment are a significant concern. Isosorbide is a renewable feedstock alternative to petroleum derivatives for commercial polymer production. It is derived from plants, and, as one of the top 20 biomass sourced molecules, is available at a scale that is consistent with commercial production of bioplastics.”

Duke University professor Dr. Matthew Becker said: “Most bio-sourced plastics have lacked the mechanical properties needed to compete in commercial applications and lose nearly all of their mechanical properties when reprocessed. The materials outlined in this paper change that paradigm”.

A joint patent application has been filed by the University of Birmingham Enterprise and Duke University, covering both the polymers and the method of making them. The researchers are now looking for industrial partners who are interested in licensing the technology.

A KAIST team compute express link (CXL) provides new insights on memory disaggregation and ensures direct access and high-performance capabilities

A team from the Computer Architecture and Memory Systems Laboratory (CAMEL) at KAIST presented a new compute express link (CXL) solution whose directly accessible, and high-performance memory disaggregation opens new directions for big data memory processing. Professor Myoungsoo Jung said the team’s technology significantly improves performance compared to existing remote direct memory access (RDMA)-based memory disaggregation.

CXL is a peripheral component interconnect-express (PCIe)-based new dynamic multi-protocol made for efficiently utilizing memory devices and accelerators. Many enterprise data centers and memory vendors are paying attention to it as the next-generation multi-protocol for the era of big data.  

Emerging big data applications such as machine learning, graph analytics, and in-memory databases require large memory capacities. However, scaling out the memory capacity via a prior memory interface like double data rate (DDR) is limited by the number of the central processing units (CPUs) and memory controllers. Therefore, memory disaggregation, which allows connecting a host to another host’s memory or memory nodes, has appeared.

RDMA is a way that a host can directly access another host’s memory via InfiniBand, the commonly used network protocol in data centers. Nowadays, most existing memory disaggregation technologies employ RDMA to get a large memory capacity. As a result, a host can share another host’s memory by transferring the data between local and remote memory.  

Although RDMA-based memory disaggregation provides a large memory capacity to a host, two critical problems exist. First, scaling out the memory still needs an extra CPU to be added. Since passive memory such as dynamic random-access memory (DRAM), cannot operate by itself, it should be controlled by the CPU. Second, redundant data copies and software fabric interventions for RDMA-based memory disaggregation cause longer access latency. For example, remote memory access latency in RDMA-based memory disaggregation is multiple orders of magnitude longer than local memory access.

To address these issues, Professor Jung’s team developed the CXL-based memory disaggregation framework, including CXL-enabled customized CPUs, CXL devices, CXL switches, and CXL-aware operating system modules. The team’s CXL device is a pure passive and directly accessible memory node that contains multiple DRAM dual inline memory modules (DIMMs) and a CXL memory controller. Since the CXL memory controller supports the memory in the CXL device, a host can utilize the memory node without processor or software intervention. The team’s CXL switch enables scaling out a host’s memory capacity by hierarchically connecting multiple CXL devices to the CXL switch allowing more than hundreds of devices. Atop the switches and devices, the team’s CXL-enabled operating system removes redundant data copy and protocol conversion exhibited by conventional RDMA, which can significantly decrease access latency to the memory nodes.

In a test comparing loading 64B (cache line) data from memory pooling devices, CXL-based memory disaggregation showed 8.2 times higher data load performance than RDMA-based memory disaggregation and even similar performance to local DRAM memory. In the team’s evaluations for a big data benchmark such as a machine learning-based test, CXL-based memory disaggregation technology also showed a maximum of 3.7 times higher performance than prior RDMA-based memory disaggregation technologies. 

“Escaping from the conventional RDMA-based memory disaggregation, our CXL-based memory disaggregation framework can provide high scalability and performance for diverse datacenters and cloud service infrastructures,” said Professor Jung. He went on to stress, “Our CXL-based memory disaggregation research will bring about a new paradigm for memory solutions that will lead the era of big data.” 

The study suggests ecological trade-offs between growth and death allow marine microbes with different dispersal strategies to coexist on small particles in the ocean 

Trade-offs between the benefit of colonizing new particles and the risk of being wiped out by predators allow diverse populations of marine microbes to exist together shows a study published today in eLife.

The findings help explain how a vast array of diverse bacteria and microbes coexist on floating particle rafts in oceans.

Microbial foraging in patchy environments, where resources are fragmented into particles, plays a key role in natural environments. In oceans and freshwater systems, bacteria and microbes can interact with particle surfaces in different ways: some only colonize them for short periods, while others form long-lived, stable colonies.

Scientists have long puzzled over the greater-than-expected diversity of microscopic creatures in oceans, a phenomenon called the 'plankton paradox'. While researchers have begun to understand the factors that support so many different types of plankton, many questions remain about the more plentiful ocean microbes that live on floating particles. 

"We wanted to study the role that dispersal strategies play in the successful coexistence of different microbes living on the same set of particles," says co-first author Ali Ebrahimi, who completed the study while he was a postdoctoral fellow at the Ralph M. Parsons Laboratory for Environmental Science and Engineering, Massachusetts Institute of Technology (MIT), Cambridge, US.

Ebrahimi and the team used mathematical modeling and computer simulations to test how different dispersal strategies may help marine microbes exist together in this way. They found that differently navigating the trade-offs between growth and survival can allow microbes to thrive together.

Their model showed that organisms that stay put on a single particle for longer have more opportunities to multiply. However, they face a higher risk of being wiped out by a virus or other predator capable of engulfing whole particles. On the other hand, microbes that more frequently hop between particles have less opportunity to multiply, but also have a lower risk of facing a mass mortality event. The success of one strategy over another may depend on differing environmental conditions.

"When the particle supply is high, microbes that hop rapidly between them will have a greater chance of survival," explains co-first author Akshit Goyal, Physics of Living Systems Fellow at the MIT Department of Physics. "But when particles are harder to come by, the bacteria that stay put will have an advantage."

Additionally, the team found that coexistence can remain stable in the face of changing environmental conditions, such as algal blooms of particles, favoring growth, and changing numbers of predators, favoring mortality. Together, these differing factors significantly increase the likelihood that populations with diverse dispersal strategies can live together.

"Our work focused on the link between dispersal and mortality in the ocean, but there’s plenty more going on in these environments," Goyal concludes. "Future research could provide important new insights on how environmental changes might impact these minuscule communities and, in turn, their wider marine ecosystem."

Co-first authors Ebrahimi and Goyal worked on this study alongside senior author Otto Cordero, Associate Professor at the MIT Department of Civil and Environmental Engineering.

Earthquakes themselves affect the movement of Earth's tectonic plates, which in turn could impact future earthquakes, according to new research from the University of Copenhagen. This new knowledge should be incorporated in computer models used to gauge earthquake risk, according to the researchers behind the study.

Like a gigantic puzzle, Earth’s tectonic plates divide the surface of our planet into larger and smaller pieces. These pieces are in constant motion due to the fluid-like part of Earth’s mantle, upon which they slowly sail. These movements regularly trigger earthquakes, some of which can devastate cities and cost thousands of lives. In 1999, the strongest European earthquake in recent years struck the town of İzmit, Turkey – taking the lives of 17,000 of its residents.

Among researchers and earthquake experts, it is well accepted that earthquakes are caused by a one-way mechanism: as plates move against one another, energy is slowly accrued along plate margins, and then suddenly released via earthquakes. This happens time and again over decades- or century-long intervals, in a constant stick-slip motion.

But in a new study, researchers from the Geology Section at the University of Copenhagen’s Department of Geosciences and Natural Resource Management demonstrate that the behavior of tectonic plates can change following an earthquake.

Using extensive GPS data and analysis of the 1999 İzmit earthquake, the researchers have been able to conclude that the Anatolian continental plate that Turkey sits upon has changed direction since the earthquake. Data also show that this influenced the frequency of quakes around Turkey after 1999.

"It appears that the link between plate motion - earthquake occurrence is not a one-way street. Earthquakes themselves feedback, as they can cause plates to move differently afterward," explains the study’s lead author, postdoc Juan Martin De Blas, who adds:

"As the plate movements change, it somewhat affects the pattern of the later earthquakes. If a tectonic plate shifts direction or moves at a different rate than before, this potentially impacts onto the seismicity of its margins with neighboring plates."

Quake models  can be improved

According to the researchers, the new findings provide a clear basis for reevaluating the risk models that interpret data gathered from the monitoring of tectonic plate movements. This data is used to assess the risk of future earthquakes in terms of probability, somehow like the nice/bad weather forecast.  

"An important aspect of these models is that they operate under the assumption that plate movements remain constant. With this study, we can see that this isn’t the case. Therefore, the models can now be further evolved so they take the feedback mechanism that occurs following an earthquake into account, where plates shift direction and speed," says Associate Professor Giampiero Iaffaldano, the study’s co-author.

The assumption that plate movements are constant has largely been a "necessary" assumption according to the researchers because monitoring plate motions over a few years were once impossible. But with the advent of geodesy in Geosciences and the extensive and ever-growing use of GPS devices over the last 20 years, we can track plate motion changes over year-long periods.

Could make us better at assessing risk

How tectonic plates are monitored varies greatly from place to place. Often GPS transmitters are positioned preferentially near the edges of a tectonic plate. This allows public agencies and researchers to track the movement of plate boundaries. But according to the researchers, we can also benefit from even more GPS devices continuously monitoring plate interiors, away from their margins.

"Plate boundaries undergo constant deformation and poorly represent the movement of plates as a whole. Therefore, GPS data from monitors positioned farther away from the plate boundaries should be used to a much greater degree. This can better inform us weather plates are changing motion and how, and provide information useful for assessing the risk of future events somewhere other than the known hot-spots," says Giampiero Iaffaldano.

The researchers point out that their study is limited to the Anatolian continental plate, as the İzmit earthquake is one of the few events for which a combination of sufficient seismic and GPS data is available. However, they expect that the picture is the same for other tectonic plates around the planet.