Researchers at China's Tsinghua University used ion-selective membranes of ultrathin graphene oxide (GO) to develop a novel, ion-selective but highly permeable separator for significantly improving both the energy density and power density of lithium-sulfur batteries. This resulted in a highly-stable and anti-self-discharge lithium-sulfur cell.
Polysulfides are materials generated at the cathode side, diffuse through the membrane, react with lithium anode, and shuttle back. During the process, polysulfides dissolve and irreversibly react with metal lithium and organic components, inducing the destruction of the cathode structure, depletion of the lithium anode, and loss of active sulfur materials. Commonly used separators in battery systems are porous polymer membranes, which separate the two electrodes while having little impact on the transportation of ions through the membrane. The researchers' design was of a GO membrane, sandwiched between cathode and anode electrodes, which efficiently prohibited the shuttle of polysulfides through the membrane.
The Spanish Graphenea, along with Russian and Spanish collaborators, have shown that adding graphene to alumina improves the ceramic's wear resistance and decreases friction. The result is expected to soon find uses in real products, as graphene and its derivatives seem to be biocompatible and in addition carry a low cost.
Alunima (an oxide of aluminium) has been long in use in biomedical applications such as load-bearing hip prostheses and dental implants, due to its high resistance to corrosion, low friction, high wear resistance and strength. This recent study describes the dry sliding behavior of a graphene/alumina composite material and compares it to regular alumina. The wear rate of the advanced composite was 50% lower than that of pure alumina, while the friction coefficient was reduced by 10%. This finding is made even more astonishing by the fact that the concentration of graphene in the final product is only 0.22% by weight. The type of graphene used for the study is Graphenea's standard graphene oxide.
Back in 2013, Rice scientists developed a simple method to reduce coal into graphene quantum dots (GQDs). Now, these Rice researchers have found a way to engineer these GQDs for specific semiconducting properties in two separate processes.
The researchers' work demonstrates precise control over the graphene oxide dots' band gap, the very property that makes them semiconductors. By sorting the QDs through ultrafiltration, it was found possible to produce quantum dots with specific semiconducting properties. The second process involved direct control of the reaction temperature in the oxidation process that reduced coal to quantum dots. The researchers found hotter temperatures produced smaller dots that had different semiconducting properties. The dots in these experiments came from treatment of anthracite, a kind of coal. The processes produce batches in specific sizes between 4.5 and 70 nanometers in diameter.
Scientists at the Natural Science Foundation and the Hospital-Public Cross-Link Project of Shanghai Jiao Tong University discovered that graphene oxide might be helpful in eliminating antibiotic-resistant bacteria that causes tooth decay and gum disease.
Graphene oxide is able to inhibit the growth of certain bacterial strains with minimal harm to cells. The researchers tested it against three different species of bacteria that are also linked to tooth decay and gum disease. Findings showed that graphene oxide effectively slowed the growth of the pathogens.
Researchers from the Bourns College of Engineering at the University of California, Riverside investigated a strategy to improve lithium-sulfur batteries' performance by creating nano-sized sulfur particles, and coating them in glass.
Lithium-sulfur batteries have been attracting attention thanks to their ability to produce up to 10 times more energy than conventional batteries, but one of the main roadblocks to implementing them is a the tendency for lithium and sulfur reaction products (called lithium polysulfides) to dissolve in the battery’s electrolyte and travel to the opposite electrode permanently, which causes the battery’s capacity to decrease over its lifetime. The scientists designed a cathode material in which silica (glass) cages “trap” polysulfides.. The team used an organic precursor to construct the trapping barrier.
Scientists at the University of Manchester found that graphene oxide may act as an anti-cancer agent that selectively targets cancer stem cells (CSCs). In combination with existing treatments, this could eventually lead to tumor shrinkage as well as preventing the spread of cancer and its recurrence after treatment.
The team prepared a variety of graphene oxide formulations for testing against six different cancer types - breast, pancreatic, lung, brain, ovarian and prostate. The flakes inhibited the formation of tumor sphere formation in all six types, suggesting that graphene oxide can be effective across a large number of different cancers, by blocking processes which take place at the surface of the cells. The researchers suggest that this may deliver a better overall clinical outcome when used in combination with conventional cancer treatments.
A recent study performed at Rice University explored the toxicity of different nanomaterials. A major difficulty in assessing nanomaterial toxicity is that there are many different varieties of nanomaterials and it is too costly to test all of them using traditional methods. The goal of the study was to develop a low-cost, high-throughput method to solve this problem.
The scientists achieved this goal by testing nanomaterials on a worm called Nematode C. Elegans. They designed assays that can test hundreds of nanomaterials in a week. These assays test the effects of each nanomaterial on thousands of worms. The material cost for each assay is only about 50 cents. As a demonstration, they applied their technology to test 20 nanomaterials and found that most of them showed some degree of toxicity. This method can serve effectively as a rapid initial screen to prioritize a few nanomaterials for more expensive, dedicated toxicology testing.