Scientists use laser imaging to assess safety of zinc oxide nanoparticles in sunscreen

ScienceDaily (Nov. 30, 2011) — Ultra-tiny zinc oxide (ZnO) particles with dimensions less than one-ten-millionth of a meter are among the ingredients list of some commercially available sunscreen products, raising concerns about whether the particles may be absorbed beneath the outer layer of skin. To help answer these safety questions, an international team of scientists from Australia and Switzerland have developed a way to optically test the concentration of ZnO nanoparticles at different skin depths. They found that the nanoparticles did not penetrate beneath the outermost layer of cells when applied to patches of excised skin.

The results, which were published this month in the Optical Society's (OSA) open-access journal Biomedical Optics Express, lay the groundwork for future studies in live patients.

The high optical absorption of ZnO nanoparticles in the UVA and UVB range, along with their transparency in the visible spectrum when mixed into lotions, makes them appealing candidates for inclusion in sunscreen cosmetics. However, the particles have been shown to be toxic to certain types of cells within the body, making it important to study the nanoparticles' fate after being applied to the skin. By characterizing the optical properties of ZnO nanoparticles, the Australian and Swiss research team found a way to quantitatively assess how far the nanoparticles might migrate into skin.

The team used a technique called nonlinear optical microscopy, which illuminates the sample with short pulses of laser light and measures a return signal. Initial results show that ZnO nanoparticles from a formulation that had been rubbed into skin patches for 5 minutes, incubated at body temperature for 8 hours, and then washed off, did not penetrate beneath the stratum corneum, or topmost layer of the skin. The new optical characterization should be a useful tool for future non-invasive in vivo studies, the researchers write.

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Zhen Song, Timothy A. Kelf, Washington H. Sanchez, Michael S. Roberts, Jaro Ricka, Martin Frenz, Andrei V. Zvyagin. Characterization of optical properties of ZnO nanoparticles for quantitative imaging of transdermal transport. Biomedical Optics Express, 2011; 2 (12): 3321 DOI: 10.1364/BOE.2.003321

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Scientists propose new names for elements 114 and 116

ScienceDaily (Dec. 1, 2011) — The International Union of Pure and Applied Chemistry (IUPAC) have recommended new proposed names for elements 114 and 116, the latest heavy elements to be added to the periodic table.

Scientists of the Lawrence Livermore National Laboratory (LLNL)-Dubna collaboration proposed the names as Flerovium for element 114 and Livermorium for element 116.

In June 2011, the IUPAC officially accepted elements 114 and 116 as the heaviest elements, more than 10 years after scientists from the Joint Institute for Nuclear Research in Dubna and Lawrence Livermore chemists discovered them.

Flerovium (atomic symbol Fl) was chosen to honor Flerov Laboratory of Nuclear Reactions, where superheavy elements, including element 114, were synthesized. Georgiy N. Flerov (1913-1990) was a renowned physicist who discovered the spontaneous fission of uranium and was a pioneer in heavy-ion physics. He is the founder of the Joint Institute for Nuclear Research. In 1991, the laboratory was named after Flerov -- Flerov Laboratory of Nuclear Reactions (FLNR).

Livermorium (atomic symbol Lv) was chosen to honor Lawrence Livermore National Laboratory (LLNL) and the city of Livermore, Calif. A group of researchers from the Laboratory, along with scientists at the Flerov Laboratory of Nuclear Reactions, participated in the work carried out in Dubna on the synthesis of superheavy elements, including element 116. (Lawrencium -- Element 103 -- was already named for LLNL's founder E.O. Lawrence.)

In 1989, Flerov and Ken Hulet (1926-2010) of LLNL established collaboration between scientists at LLNL and scientists at FLNR; one of the results of this long-standing collaboration was the synthesis of elements 114 and 116.

"Proposing these names for the elements honors not only the individual contributions of scientists from these laboratories to the fields of nuclear science, heavy element research, and superheavy element research, but also the phenomenal cooperation and collaboration that has occurred between scientists at these two locations," said Bill Goldstein, associate director of LLNL's Physical and Life Sciences Directorate.

LLNL scientists Ken Moody, Dawn Shaughnessy, Jackie Kenneally and Mark Stoyer were critical members of the team along with a team of retired LLNL scientists including John Wild, Ron Lougheed and Jerry Landrum. Former LLNL scientists Nancy Stoyer, Carola Gregorich, Jerry Landrum, Joshua Patin and Philip Wilk also were on the team. The research was supported by LLNL Laboratory Research and Development funds (LDRD).

Scientists at LLNL have been involved in heavy element research since the Laboratory's inception in 1952 and have been collaborators in the discovery of six elements -- 113,114,115,116,117 and 118.

Livermore also has been at the forefront of investigations into other areas related to nuclear science such as cross-section measurements, nuclear theory, radiochemical diagnostics of laser-induced reactions, separations chemistry including rapid automated aqueous separations, actinide chemistry, heavy-element target fabrication, and nuclear forensics.

The creation of elements 116 and 114 involved smashing calcium ions (with 20 protons each) into a curium target (96 protons) to create element 116. Element 116 decayed almost immediately into element 114. The scientists also created element 114 separately by replacing curium with a plutonium target (94 protons).

The creation of elements 114 and 116 generate hope that the team is on its way to the "island of stability," an area of the periodic table in which new heavy elements would be stable or last long enough for applications to be found.

The new names were submitted to the IUPAC in late October and now remain in the public domain. The new names will not be official until about five months from now when the public comment period is over.

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Setting the stage for life: Scientists make key discovery about the atmosphere of early Earth

ScienceDaily (Nov. 30, 2011) — Scientists in the New York Center for Astrobiology at Rensselaer Polytechnic Institute have used the oldest minerals on Earth to reconstruct the atmospheric conditions present on Earth very soon after its birth. The findings, which appear in the Dec. 1 edition of the journal Nature, are the first direct evidence of what the ancient atmosphere of the planet was like soon after its formation and directly challenge years of research on the type of atmosphere out of which life arose on the planet.

The scientists show that the atmosphere of Earth just 500 million years after its creation was not a methane-filled wasteland as previously proposed, but instead was much closer to the conditions of our current atmosphere. The findings, in a paper titled "The oxidation state of Hadean magmas and implications for early Earth's atmosphere," have implications for our understanding of how and when life began on this planet and could begin elsewhere in the universe.

For decades, scientists believed that the atmosphere of early Earth was highly reduced, meaning that oxygen was greatly limited. Such oxygen-poor conditions would have resulted in an atmosphere filled with noxious methane, carbon monoxide, hydrogen sulfide, and ammonia. To date, there remain widely held theories and studies of how life on Earth may have been built out of this deadly atmosphere cocktail.

Now, scientists at Rensselaer are turning these atmospheric assumptions on their heads with findings that prove the conditions on early Earth were simply not conducive to the formation of this type of atmosphere, but rather to an atmosphere dominated by the more oxygen-rich compounds found within our current atmosphere -- including water, carbon dioxide, and sulfur dioxide.

"We can now say with some certainty that many scientists studying the origins of life on Earth simply picked the wrong atmosphere," said Bruce Watson, Institute Professor of Science at Rensselaer.

The findings rest on the widely held theory that Earth's atmosphere was formed by gases released from volcanic activity on its surface. Today, as during the earliest days of the Earth, magma flowing from deep in the Earth contains dissolved gases. When that magma nears the surface, those gases are released into the surrounding air.

"Most scientists would argue that this outgassing from magma was the main input to the atmosphere," Watson said. "To understand the nature of the atmosphere 'in the beginning,' we needed to determine what gas species were in the magmas supplying the atmosphere."

As magma approaches Earth's surface, it either erupts or stalls in the crust, where it interacts with surrounding rocks, cools, and crystallizes into solid rock. These frozen magmas and the elements they contain can be literal milestones in the history of Earth.

One important milestone is zircon. Unlike other materials that are destroyed over time by erosion and subduction, certain zircons are nearly as old as Earth itself. As such, zircons can literally tell the entire history of the planet -- if you know the right questions to ask.

The scientists sought to determine the oxidation levels of the magmas that formed these ancient zircons to quantify, for the first time ever, how oxidized were the gases being released early in Earth's history. Understanding the level of oxidation could spell the difference between nasty swamp gas and the mixture of water vapor and carbon dioxide we are currently so accustomed to, according to study lead author Dustin Trail, a postdoctoral researcher in the Center for Astrobiology.

"By determining the oxidation state of the magmas that created zircon, we could then determine the types of gases that would eventually make their way into the atmosphere," said Trail.

To do this Trail, Watson, and their colleague, postdoctoral researcher Nicholas Tailby, recreated the formation of zircons in the laboratory at different oxidation levels. They literally created lava in the lab. This procedure led to the creation of an oxidation gauge that could then be compared with the natural zircons.

During this process they looked for concentrations of a rare Earth metal called cerium in the zircons. Cerium is an important oxidation gauge because it can be found in two oxidation states, with one more oxidized than the other. The higher the concentrations of the more oxidized type cerium in zircon, the more oxidized the atmosphere likely was after their formation.

The calibrations reveal an atmosphere with an oxidation state closer to present-day conditions. The findings provide an important starting point for future research on the origins of life on Earth.

"Our planet is the stage on which all of life has played out," Watson said. "We can't even begin to talk about life on Earth until we know what that stage is. And oxygen conditions were vitally important because of how they affect the types of organic molecules that can be formed."

Despite being the atmosphere that life currently breathes, lives, and thrives on, our current oxidized atmosphere is not currently understood to be a great starting point for life. Methane and its oxygen-poor counterparts have much more biologic potential to jump from inorganic compounds to life-supporting amino acids and DNA. As such, Watson thinks the discovery of his group may reinvigorate theories that perhaps those building blocks for life were not created on Earth, but delivered from elsewhere in the galaxy.

The results do not, however, run contrary to existing theories on life's journey from anaerobic to aerobic organisms. The results quantify the nature of gas molecules containing carbon, hydrogen, and sulfur in the earliest atmosphere, but they shed no light on the much later rise of free oxygen in the air. There was still a significant amount of time for oxygen to build up in the atmosphere through biologic mechanisms, according to Trail.

The research was funded by NASA.

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Dustin Trail, E. Bruce Watson, Nicholas D. Tailby. The oxidation state of Hadean magmas and implications for early Earth’s atmosphere. Nature, 2011; 480 (7375): 79 DOI: 10.1038/nature10655

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Some atheist scientists with children embrace religious traditions, according to new research

ScienceDaily (Dec. 1, 2011) — Some atheist scientists with children embrace religious traditions for social and personal reasons, according to research from Rice University and the University at Buffalo -- The State University of New York (SUNY).

The study also found that some atheist scientists want their children to know about different religions so their children can make informed decisions about their own religious preferences.

"Our research shows just how tightly linked religion and family are in U.S. society -- so much so that even some of society's least religious people find religion to be important in their private lives," said Rice sociologist Elaine Howard Ecklund, the study's principal investigator and co-author of a paper in the December issue of the Journal for the Scientific Study of Religion.

The researchers found that 17 percent of atheists with children attended a religious service more than once in the past year.

The research was conducted through interviews with a scientifically selected sample of 275 participants pulled from a survey of 2,198 tenured and tenure-track faculty in the natural and social sciences at 21 elite U.S. research universities. Approximately half of the original survey population expressed some form of religious identity, whereas the other half did not.

The individuals surveyed cited personal and social reasons for integrating religion into their lives, including:

Scientific identity -- Study participants wish to expose their children to all sources of knowledge (including religion) and allow them to make their own choices about a religious identity.Spousal influence -- Study participants are involved in a religious institution because of influence from their spouse or partner.Desire for community -- Study participants want a sense of moral community and behavior, even if they don't agree with the religious reasoning.

Ecklund said one of the most interesting findings was discovering that not only do some atheist scientists wish to expose their children to religious institutions, but they also cite their scientific identity as reason for doing so.

"We thought that these individuals might be less inclined to introduce their children to religious traditions, but we found the exact opposite to be true," Ecklund said. "They want their children to have choices, and it is more consistent with their science identity to expose their children to all sources of knowledge."

One study participant raised in a strongly Catholic home said he came to believe later that science and religion were not compatible. He said what he wants to pass on to his daughter -- more than the belief that science and religion are not compatible -- is the ability to make her own decisions in a thoughtful, intellectual way.

"I … don't indoctrinate her that she should believe in God," the study participant said. "I don't indoctrinate her into not believing in God." He said he sees himself as accomplishing this by exposing her to a variety of religious choices, including Christianity, Islam, Buddhism and others.

Ecklund said the study's findings will help the public better understand the role that religious institutions play in society.

"I think that understanding how nonreligious scientists utilize religion in family life demonstrates the important function they have in the U.S.," she said.

Ecklund is the author of "Science vs. Religion: What Scientists Really Think,"published by Oxford University Press last year.

The paper was co-authored by University at Buffalo SUNY sociologist Kristen Schultz Lee. A grant from the John Templeton Foundation and funding from Rice supported the research.

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Elaine Howard Ecklund, Kristen Schultz Lee. Atheists and Agnostics Negotiate Religion and Family. Journal for the Scientific Study of Religion, Volume 50, Issue 4, pages 728%u2013743, December 2011 DOI: 10.1111/j.1468-5906.2011.01604.x

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Shaken, not stirred: Scientists spy molecular maneuvers

ScienceDaily (Oct. 27, 2011) — Stir this clear liquid in a glass vial and nothing happens. Shake this liquid, and free-floating sheets of protein-like structures emerge, ready to detect molecules or catalyze a reaction. This isn't the latest gadget from James Bond's arsenal -- rather, the latest research from the U. S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) scientists unveiling how slim sheets of protein-like structures self-assemble. This "shaken, not stirred" mechanism provides a way to scale up production of these two-dimensional nanosheets for a wide range of applications, such as platforms for sensing, filtration and templating growth of other nanostructures.

"Our findings tell us how to engineer two-dimensional, biomimetic materials with atomic precision in water," said Ron Zuckermann, Director of the Biological Nanostructures Facility at the Molecular Foundry, a DOE nanoscience user facility at Berkeley Lab. "What's more, we can produce these materials for specific applications, such as a platform for sensing molecules or a membrane for filtration."

Zuckermann, who is also a senior scientist at Berkeley Lab, is a pioneer in the development of peptoids, synthetic polymers that behave like naturally occurring proteins without degrading. His group previously discovered peptoids capable of self-assembling into nanoscale ropes, sheets and jaws, accelerating mineral growth and serving as a platform for detecting misfolded proteins.

In this latest study, the team employed a Langmuir-Blodgett trough -- a bath of water with Teflon-coated paddles at either end -- to study how peptoid nanosheets assemble at the surface of the bath, called the air-water interface. By compressing a single layer of peptoid molecules on the surface of water with these paddles, said Babak Sanii, a post-doctoral researcher working with Zuckermann, "we can squeeze this layer to a critical pressure and watch it collapse into a sheet."

"Knowing the mechanism of sheet formation gives us a set of design rules for making these nanomaterials on a much larger scale," added Sanii.

To study how shaking affected sheet formation, the team developed a new device called the SheetRocker to gently rock a vial of peptoids from upright to horizontal and back again. This carefully controlled motion allowed the team to precisely control the process of compression on the air-water interface.

"During shaking, the monolayer of peptoids essentially compresses, pushing chains of peptoids together and squeezing them out into a nanosheet. The air-water interface essentially acts as a catalyst for producing nanosheets in 95% yield," added Zuckermann. "What's more, this process may be general for a wide variety of two-dimensional nanomaterials."

This research is reported in a paper titled, "Shaken, not stirred: Collapsing a peptoid monolayer to produce free-floating, stable nanosheets," appearing in the Journal of the American Chemical Society (JACS) and available in JACS online. Co-authoring the paper with Zuckermann and Sanii were Romas Kudirka, Andrew Cho, Neeraja Venkateswaran, Gloria Olivier, Alexander Olson, Helen Tran, Marika Harada and Li Tan.

This work at the Molecular Foundry was supported by DOE's Office of Science and the Defense Threat Reduction Agency.

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Babak Sanii, Romas Kudirka, Andrew Cho, Neeraja Venkateswaran, Gloria K. Olivier, Alexander M. Olson, Helen Tran, R. Marika Harada, Li Tan, Ronald N. Zuckermann. Shaken, Not Stirred: Collapsing a Peptoid Monolayer To Produce Free-Floating, Stable Nanosheets. Journal of the American Chemical Society, 2011; : 111012114427004 DOI: 10.1021/ja206199d

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Scientists measure dream content for the first time: Dreams activate the brain in a similar way to real actions

ScienceDaily (Oct. 28, 2011) — The ability to dream is a fascinating aspect of the human mind. However, how the images and emotions that we experience so intensively when we dream form in our heads remains a mystery. Up to now it has not been possible to measure dream content. Max Planck scientists working with colleagues from the Charité hospital in Berlin have now succeeded, for the first time, in analysing the activity of the brain during dreaming.

They were able to do this with the help of lucid dreamers, i.e. people who become aware of their dreaming state and are able to alter the content of their dreams. The scientists measured that the brain activity during the dreamed motion matched the one observed during a real executed movement in a state of wakefulness.

The research is published in the journal Current Biology.

Methods like functional magnetic resonance imaging have enabled scientists to visualise and identify the precise spatial location of brain activity during sleep. However, up to now, researchers have not been able to analyse specific brain activity associated with dream content, as measured brain activity can only be traced back to a specific dream if the precise temporal coincidence of the dream content and measurement is known. Whether a person is dreaming is something that could only be reported by the individual himself.

Scientists from the Max Planck Institute of Psychiatry in Munich, the Charité hospital in Berlin and the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig availed of the ability of lucid dreamers to dream consciously for their research. Lucid dreamers were asked to become aware of their dream while sleeping in a magnetic resonance scanner and to report this "lucid" state to the researchers by means of eye movements. They were then asked to voluntarily "dream" that they were repeatedly clenching first their right fist and then their left one for ten seconds.

This enabled the scientists to measure the entry into REM sleep -- a phase in which dreams are perceived particularly intensively -- with the help of the subject's electroencephalogram (EEG) and to detect the beginning of a lucid phase. The brain activity measured from this time onwards corresponded with the arranged "dream" involving the fist clenching. A region in the sensorimotor cortex of the brain, which is responsible for the execution of movements, was actually activated during the dream. This is directly comparable with the brain activity that arises when the hand is moved while the person is awake. Even if the lucid dreamer just imagines the hand movement while awake, the sensorimotor cortex reacts in a similar way.

The coincidence of the brain activity measured during dreaming and the conscious action shows that dream content can be measured. "With this combination of sleep EEGs, imaging methods and lucid dreamers, we can measure not only simple movements during sleep but also the activity patterns in the brain during visual dream perceptions," says Martin Dresler, a researcher at the Max Planck Institute for Psychiatry.

The researchers were able to confirm the data obtained using MR imaging in another subject using a different technology. With the help of near-infrared spectroscopy, they also observed increased activity in a region of the brain that plays an important role in the planning of movements. "Our dreams are therefore not a 'sleep cinema' in which we merely observe an event passively, but involve activity in the regions of the brain that are relevant to the dream content," explains Michael Czisch, research group leader at the Max Planck Institute for Psychiatry.

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Martin Dresler, Stefan P. Koch, Renate Wehrle, Victor I. Spoormaker, Florian Holsboer, Axel Steiger, Philipp G. Sämann, Hellmuth Obrig, Michael Czisch. Dreamed Movement Elicits Activation in the Sensorimotor Cortex. Current Biology, Published online Oct. 27, 2011 DOI: 10.1016/j.cub.2011.09.029

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