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Clay-Based Antibiotics Kill Resistant Pathogens
Use of modern antibiotics has significantly reduced the number and severity of bacterial infections worldwide. Liberal or unrestrained use of antibiotics, however, allows some strains of bacteria to develop antibiotic resistance and become immune to traditional treatments. To tackle these especially resilient strains, Lawrence Livermore geochemists and biologists sought to rethink antibacterial formulation. Research published in the January 24, 2022, issue of Scientific Reports, points to the mineral components of naturally occurring clays as a promising antimicrobial source.
Clays rich in pyrite and smectite minerals have been known to express antimicrobial properties with the potential to kill antibiotic-resistant bacteria. The Livermore team developed an artificial geochemical process using hydrothermal reactors to produce mineral substances that exhibit the same physical characteristics and reactivity absent the inconsistencies found in natural deposits. The synthetic clay formulations were tested on pathogens that have eluded conventional antibiotics and found to neutralize those pathogens in less than one hour of direct exposure.
The researchers then applied the minerals to mammalian fibroblast cells to assess whether the concocted alternative could safely eradicate pathogens in humans. Despite initial toxicity, the cells were able to safely regenerate once the antibiotic minerals were removed. Lead researcher Keith Morrison notes that the results “indicate that mammalian cells may experience minimal toxicity while invading pathogens are killed,” raising hopes that the use of synthetic antimicrobial minerals to fight resistant strains may be imminent.
Contact: Keith Morrison (925) 423-1342 (morrison30@llnl.gov).
Plasma-Based Lenses Show Potential
Powerful laser systems like those housed at the National Ignition Facility employ a wide array of optics made to redirect, amplify, and focus light beams to deliver a precise, intense shot at a target. These solid-state optical components are susceptible to physical damage from the extraordinary levels of energy they encounter. Despite constant design and resilience improvements, even the most robust optics will be unable withstand the relentless petawatt beam energies produced by an imminent generation of ultrahigh-power laser systems. In an article published February 8, 2022, in Physical Review Letters, the research team, led by Livermore physicist Matthew Edwards, outlines the potential for diffractive plasma-based lenses to resist damage.
While plasma-based gratings, amplifiers, and mirrors have previously been demonstrated, focusing light by means of a plasma lens has proven challenging in high-repetition-rate experiments. The new lens design comes in two variations that make use of diffraction. The first relies on the precise excitation of a confined inert gas by two lasers; the resulting interference pattern produces concentric regions of plasma and gas. In the second design, lasers shape an existing plasma into the same configuration due to the plasma’s tendency to be expelled from laser-excited regions. The result is a means of focusing the beam pulse that is exponentially smaller and more resistant to damage than even advanced solid-state optics.
The scientists tested both designs via computer simulation under a variety of conditions. The second method proved most effective in silico, capable of focusing beam intensities of up to 1017 watts per centimeter squared. With such high damage resistance, plasma lenses may be integrated into future ultrahigh-energy laser systems.
Contact: Pierre Michel (925) 424-4819 (michel7@llnl.gov).
New Methods Detect Effective Climate Mitigation Efforts
As researchers worldwide scramble for new technologies and policies to mitigate the effects of climate change, Lawrence Livermore climate scientist Mark Zelinka and international collaborators have devised statistical methods to more quickly detect changes in the global warming rate. In their study published March 24, 2022, in Nature Communications, the scientists’ new methods filter out the noise of natural climate variability so that the signal—slowed warming from future emissions reductions—can shine through.
Trends in global temperature reflect not just the slow, steady rise associated with human emissions but also the short-term effects of natural fluctuations. For example, natural climate cycles like El Niño can make one year much warmer than prior years, obscuring whether emissions reductions are having a tangible effect on global climate. Drawing upon an approach pioneered by Zelinka and his Livermore colleagues, the team estimated and removed contributions from natural fluctuations on the global warming rate, allowing more easily detectable changes.
Previous methods could take up to 20 years to detect slowed global warming from emissions reductions. The new climate variability noise filter cuts this time in half. This means scientists and policymakers can gauge how emissions reductions alter the warming rate and whether nations are on track to meet their climate goals.
Contact: Mark Zelinka (925) 423-5146 (zelinka1@llnl.gov).
