Laser surgery technique gets new life in art restoration

A laser technique best known for its use to remove unwanted tattoos from the skin is finding a second life in preserving great sculptures, paintings and other works of art, according to an article in ACS' monthly journal, Accounts of Chemical Research. The technique, called laser ablation, involves removing material from a solid surface by vaporizing the material with a laser beam.

Salvatore Siano and Renzo Salimbeni point out that laser cleaning of artworks actually began about 10 years before the better known medical and industrial applications of the technique. Doctors, for example, use laser ablation in medicine to remove unwanted tattoos from the skin. In industry, the technique can remove paints, coatings and other material without damaging the underlying surface.

In the article, the scientists note that laser ablation has had an important impact in preserving the world's cultural heritage of great works of art. They describe the latest advances in laser cleaning of stone and metal statues and wall paintings, including masterpieces like Lorenzo Ghiberti's Porta del Paradiso and Donatello's David. They also discuss encouraging results of laser cleaning underwater for materials that could deteriorate if exposed to air.

Accounts of Chemical Research: "Advances in Laser Cleaning of Artwork and Objects of Historical Interest: The Optimized Pulse Duration Approach" [Acc. Chem. Res., Article ASAP, DOI: 10.1021/ar900190f].

An electrifying discovery: New material to harvest electricity from body movements

Scientists are reporting an advance toward scavenging energy from walking, breathing, and other natural body movements to power electronic devices like cell phones and heart pacemakers. In a study in ACS' monthly journal, Nano Letters, they describe development of flexible, biocompatible rubber films for use in implantable or wearable energy harvesting systems. The material could be used, for instance, to harvest energy from the motion of the lungs during breathing and use it to run pacemakers without the need for batteries that must be surgically replaced every few years.

Michael McAlpine and colleagues point out that popular hand-held consumer electronic devices are using smaller and smaller amounts of electricity. That opens the possibility of supplementing battery power with electricity harvested from body movements. So-called "piezoelectric" materials are the obvious candidates, since they generate electricity when flexed or subjected to pressure. However, manufacturing piezoelectric materials requires temperatures of more than 1,000 degrees F., making it difficult to combine them with rubber.

The scientists describe a new manufacturing method that solves this problem. It enabled them to apply nano-sized ribbons of lead zirconate titanate (PZT) - each strand about 1/50,000th the width of a human hair - to ribbons of flexible silicone rubber. PZT is one of the most efficient piezoelectric materials developed to date and can convert 80 percent of mechanical energy into electricity. The combination resulted in a super-thin film they call 'piezo-rubber' that seems to be an excellent candidate for scavenging energy from body movements.

Nano Letters: "Piezoelectric Ribbons Printed onto Rubber for Flexible Energy Conversion" [Nano Lett., 2010, 10 (2), pp 524?528, DOI: 10.1021/nl903377u].

Neutrons poised to play big role in future scientific advances

Subatomic particles called neutrons are poised to play a big role in fighting HIV, slowing global warming, and improving manufacturing processes. The reason: They are the focus of a process called neutron scattering that provides unprecedented ways to study the chemistry of a wide range of important materials, including coal and biological cells, according to a fascinating article in Chemical & Engineering News (C&EN), ACS' weekly newsmagazine.

C&EN Associate Editor Jyllian Kemsley notes that neutrons have properties useful for studying materials. Neutrons are special because they can penetrate deeper into samples than some other probes and can interact with atoms in ways that other particles can't. This gives scientists much more information about the structure and activity of materials than some current tools.

Using neutron scattering, scientists have studied how certain fluids behave under stress, which could lead to improved manufacturing processes and products. The method also has been used by scientists to study biological processes. All three of the neutron user facilities located at government labs in the United States are in various phases of expansion. "With greater knowledge of neutrons' capabilities and increased availability, scientific progress undoubtedly awaits," the article notes.

Chemical & Engineering News: "Making Use of Neutrons" [February 22, 2010 Volume 88, Number 8pp. 36-39].

New evidence that green tea may help fight glaucoma and other eye diseases

Scientists have confirmed that the healthful substances found in green tea - renowned for their powerful antioxidant and disease-fighting properties - do penetrate into tissues of the eye. Their new report, the first documenting how the lens, retina, and other eye tissues absorb these substances, raises the possibility that green tea may protect against glaucoma and other common eye diseases. It appears in ACS's bi-weekly Journal of Agricultural and Food Chemistry.

Chi Pui Pang and colleagues point out that so-called green tea "catechins" have been among a number of antioxidants thought capable of protecting the eye. Those include vitamin C, vitamin E, lutein, and zeaxanthin. Until now, however, nobody knew if the catechins in green tea actually passed from the stomach and gastrointestinal tract into the tissues of the eye.

Pang and his colleagues resolved that uncertainty in experiments with laboratory rats that drank green tea. Analysis of eye tissues showed beyond a doubt that eye structures absorbed significant amounts of individual catechins. The retina, for example, absorbed the highest levels of gallocatechin, while the aqueous humor tended to absorb epigallocatechin. The effects of green tea catechins in reducing harmful oxidative stress in the eye lasted for up to 20 hours. "Our results indicate that green tea consumption could benefit the eye against oxidative stress," the report concludes.

Journal of Agricultural and Food Chemistry: "Green Tea Catechins and Their Oxidative Protection in the Rat Eye" [J. Agric. Food Chem., 2010, 58 (3), pp 1523?1534, DOI: 10.1021/jf9032602].

Oil droplets can navigate complex maze

Call them oil droplets with a brain or even "chemo-rats." Scientists in Illinois have developed a way to make simple oil droplets "smart" enough to navigate through a complex maze almost like a trained lab rat. The finding could have a wide range of practical implications, including helping cancer drugs to reach their target and controlling the movement of futuristic nano-machines, the scientists say. Their study is in the weekly Journal of the American Chemical Society.

Bartosz Grzybowski and colleagues note that the ability to solve a maze is a common scientific test of intelligence. Animals ranging from rats to humans can master the task. Scientists would like to pass along that same ability to anti-cancer drugs, for instance, to help these medications navigate complex mazes of blood vessels and reach the tumor.

The scientists describe an advance in that direction. They developed postage-stamp-sized mazes, and infused them with an alkaline solution, and placed a gel containing a strong acid at the exit. That created a pH gradient, a difference between the acid-alkaline levels. Oil droplets containing a weak acid placed at the entrance of the mazes developed convective flows in response to pH differences and propelled themselves along the gradient toward the exit. Since cancer cells are more acidic than other body cells, the experiment may serve as a model for designing new anti-cancer drugs that move along similar acid-based gradients to target diseased cells, the scientists suggest.

Journal of the American Chemical Society: "Maze Solving by Chemotactic Droplets" [J. Am. Chem. Soc., 2010, 132 (4), pp 1198?1199, DOI: 10.1021/ja9076793].

Answering that age-old lament: Where does all this dust come from?

Where does it come from? Scientists in Arizona are reporting a surprising answer to that question, which has puzzled and perplexed generations of men and women confronted with layers of dust on furniture and floors. Most of indoor dust comes from outdoors. Their report appears in the ACS' Environmental Science & Technology, a semi-monthly journal.

In the study, David Layton and Paloma Beamer point out that household dust consists of a potpourri that includes dead skin shed by people, fibers from carpets and upholstered furniture, and tracked-in soil and airborne particles blown in from outdoors. It can include lead, arsenic and other potentially harmful substances that migrate indoors from outside air and soil. That can be a special concern for children, who consume those substances by putting dust-contaminated toys and other objects into their mouths.

The scientists describe development and use on homes in the Midwest of a computer model that can track distribution of contaminated soil and airborne particulates into residences from outdoors. They found that over 60 percent of house dust originates outdoors. They estimated that nearly 60 percent of the arsenic in floor dust could come from arsenic in the surrounding air, with the remainder derived from tracked-in soil. The researchers point out the model could be used to evaluate methods for reducing contaminants in dust and associated human exposures.

Environmental Science & Technology: "Migration of Contaminated Soil and Airborne Particulates to Indoor Dust" [Environ. Sci. Technol., 2009, 43 (21), pp 8199?8205, DOI: 10.1021/es9003735].

Stitching together 'lab-on-a-chip' devices with cotton thread and sewing needles

Scientists in Australia are reporting the first use of ordinary cotton thread and sewing needles to literally stitch together a microfluidic analytical device - microscopic technology that can transport fluids for medical tests and other purposes in a lab-on-a-chip. The chips shrink room-sized diagnostic testing equipment down to the size of a postage stamp, and promise revolutionary applications in medicine, environmental sensing, and other areas. Their study is in ACS Applied Materials & Interfaces, a monthly journal.

Wei Shen and colleagues note that the development of low-cost "lab-on-a-chip" diagnostic tests has become an attractive area of research. Existing devices require etching microscopic channels onto slivers of silicon, glass, ceramics, or metal in a costly, complicated process. The scientists set out to find an alternative, and did so with cotton thread, which wicks fluids along its tiny fibers.

They stitched thread into paper to form microfluidic sensors capable of detecting and measuring substances released in the urine of patients with several human medical conditions. "The fabrication of thread-based microfluidic devices is simple and relatively low cost because it requires only sewing needles or household sewing machines," the report said. "Our results demonstrate that thread is a suitable material for fabricating microfluidic diagnostic devices for monitoring human health, environment and food safety, especially for the population in less-industrialized areas or remote regions."

Applied Materials & Interfaces: "Thread as a Versatile Material for Low-Cost Microfluidic Diagnostics" [ppl. Mater. Interfaces, 2010, 2 (1), pp 1?6; DOI: 10.1021/am9006148].

Transforming skin cells into stem cells using a molecular toolkit

In an effort to sidestep the ethical dilemma involved in using human embryonic stem cells to treat diseases, scientists are developing non-controversial alternatives: In particular, they are looking for drug-like chemical compounds that can transform adult skin cells into the stem cells now obtained from human embryos. That's the topic of a fascinating article in Chemical & Engineering News (C&EN), ACS' weekly newsmagazine.

C&EN Associate Editor Sarah Everts notes that in 2006, researchers in Japan figured out a way to use genetic engineering to coax a skin cell to become a so-called "pluripotent" stem cell - a type of cell that can potentially morph or change into any cell of the human body. The scientists achieved the result by infecting the skin cell with a virus containing certain genes instructing the cell to change.

Now chemists are trying to reproduce this cellular alchemy with drug-like substances because gene therapies have faced trouble getting into the clinic. Scientists are looking for chemical ways to go backward in cell development - to reprogram mature cells into stem cells. Others are trying to identify substances that can morph one cell directly into other cell types - for example, from a skin cell directly into a nerve cell that might treat Parkinson's disease - without the use of stem cells at all. The ultimate goal is to be able to reprogram any cell of the body into another by means of a simple molecular kit, the article notes. But as chemists start putting together toolkits with these drug-like molecules, they face many technical hurdles as well as challenges getting acceptance from the stem cell community.

Chemical & Engineering News: "Back to the future with stem cells" [Volume 88, Number 6pp. 50 - 53, February 8, 2010 ].

Extra large carbon

Heaviest halo nucleus discovered.

An exotic form of carbon has been found to have an extra large nucleus, dwarfing even the nuclei of much heavier elements like copper and zinc, in experiments performed in a particle accelerator in Japan. The discovery is reported in the current issue of Physical Review Letters and highlighted with a Viewpoint by Kirby Kemper and Paul Cottle of Florida State University in the February 8 issue of Physics.

Carbon-22, which has a nucleus comprised of 16 neutrons and 6 protons, is the heaviest atom yet discovered to exhibit a "halo nucleus." In such atoms, some of the particles that normally reside inside the nucleus move into orbits outside the nucleus, forming a halo of subatomic particles. Because atoms like carbon-22 are packed with an excessive number of neutrons, they're unstable and rapidly break apart to form lighter atoms, but they are more stable than scientists had previously expected. The extra stability is a surprise because the three particles-? two neutrons and a nucleus-? that form a halo nucleus interact in a way that is difficult for physicists to model due to the complicated mathematics necessary to describe so-called "three body" problems.

The unexpected stability has led to such halo nucleus atoms being labeled Borromean atoms in reference to an ancient pattern depicting three rings interlocked such that the removal of any one ring would cause all three to be disconnected. Borromean rings were often used to symbolize a stable union of three parts in traditional carvings and family crests.

The detection and analysis of carbon-22 sets a new milestone in challenging nuclear physics, and hails a promising era in the investigation of heavier and even more exotic nuclei as new beam facilities and more sensitive detectors come on line over the next decade. The surprising discovery of carbon-22's halo suggests that nuclear physicists will have plenty of new ground to cover in coming years.

[Kirby W. Kemper and Paul D. Cottle: A breakthrough observation for neutron dripline physics. Physics, 3, 13, February 8, 2010; DOI 10.1103/Physics.3.13]

First discovery of the female sex hormone progesterone in a plant

In a finding that overturns conventional wisdom, scientists are reporting the first discovery of the female sex hormone progesterone in a plant. Until now, scientists thought that only animals could make progesterone. A steroid hormone secreted by the ovaries, progesterone prepares the uterus for pregnancy and maintains pregnancy. A synthetic version, progestin, is used in birth control pills and other medications. The discovery is reported in the American Chemical Society's Journal of Natural Products, a monthly publication.

"The significance of the unequivocal identification of progesterone cannot be overstated," the article by Guido F. Pauli and colleagues, states. "While the biological role of progesterone has been extensively studied in mammals, the reason for its presence in plants is less apparent." They speculate that the hormone, like other steroid hormones, might be an ancient bioregulator that evolved billions of years ago, before the appearance of modern plants and animals. The new discovery may change scientific understanding of the evolution and function of progesterone in living things.

Scientists previously identified progesterone-like substances in plants and speculated that the hormone itself could exist in plants. But researchers had not found the actual hormone in plants until now. Pauli and colleagues used two powerful laboratory techniques, nuclear magnetic resonance and mass spectroscopy, to detect progesterone in leaves of the Common Walnut, or English Walnut, tree. They also identified five new progesterone-related steroids in a plant belonging to the buttercup family.

Journal of Natural Products: "Occurrence of Progesterone and Related Animal Steroids in Two Higher Plants" [J. Nat. Prod., January 28, 2010; DOI: 10.1021/np9007415].

Toward safer plastics that lock in potentially harmful plasticizers

Scientists have published the first report on a new way of preventing potentially harmful plasticizers - the source of long-standing human health concerns - from migrating from one of the most widely used groups of plastics. The advance could lead to a new generation of polyvinyl chloride (PVC) plastics that are safer than those now used in packaging, medical tubing, toys, and other products, they say. Their study is in ACS' Macromolecules, a bi-weekly journal.

Helmut Reinecke and colleagues note that manufacturers add large amounts of plasticizers to PVC to make it flexible and durable. Plasticizers may account for more than one-third of the weight of some PVC products. Phthalates are the mainstay plasticizers. Unfortunately, they migrate to the surface of the plastic over time and escape into the environment. As a result, PVC plastics become less flexible and durable. In addition, people who come into contact with the plastics face possible health risks. The U. S. Consumer Product Safety Commission in 2009 banned use of several phthalate plasticizers for use in manufacture of toys and child care articles.

The scientists describe development of a way to make phthalate permanently bond, or chemically attach to, the internal structure of PVC so that it will not migrate. Laboratory tests showed that the method completely suppressed the migration of plasticizer to the surface of the plastic. "This approach may open new ways to the preparation of flexible PVC with permanent plasticizer effect and zero migration," the article notes.

Macromolecules: "Phthalate Plasticizers Covalently Bound to PVC: Plasticization with Suppressed Migration" [Article ASAP; DOI: 10.1021/ma902740t].

Imaging method for eye disease used to eye art forgeries

Scientists in Poland are describing how a medical imaging technique has taken on a second life in revealing forgery of an artist's signature and changes in inscriptions on paintings that are hundreds of years old. A report on the technique, called optical coherence tomography (OCT), is in ACS' Accounts of Chemical Research, a monthly journal.

Piotr Targowski notes that easel paintings prepared according to traditional techniques consist of multiple layers. The artist, for instance, first applies a glue sizing over the canvas to ensure proper adhesion of later layers. Those layers may include an outline of the painting, the painting itself, layers of semitransparent glazes, and finally transparent varnish. Art conservators and other experts resort to a variety of technologies to see below the surface and detect changes, including forged signatures and other alterations in a painting. But those approaches may damage artistic treasures or not be sensitive enough to detect finer details.

The scientists describe how OCT, used to produce three-dimensional images of the layers of the retina of the eye, overcomes those difficulties. They used OCT to analyze two oil paintings from the 18th and 19th centuries. In one, "Saint Leonard of Porto Maurizio," OCT revealed evidence that the inscription "St. Leonard" was added approximately fifty years after completion of the painting. In the other, "Portrait of an unknown woman," OCT found evidence of the possible of forgery of the artist's signature.

Accounts of Chemical Research: "Structural Examination of Easel Paintings with Optical Coherence Tomography" [Acc. Chem. Res., Article ASAP; DOI: 10.1021/ar900195d].

Enlisting a drug discovery technique in the battle against global warming

Scientists in Texas are reporting that a technique used in the search for new drugs could also be used in the quest to discover new, environmentally friendly materials for fighting global warming. Such materials could be used to capture the greenhouse gas carbon dioxide from industrial smokestacks and other fixed sources before it enters the biosphere. The new study appears in ACS' bi-monthly journal Energy & Fuels.

Michael Drummond and colleagues Angela Wilson and Tom Cundari note that greener carbon-capture technologies are a crucial component in mitigating climate change. Existing technology is expensive and can generate hazardous waste. They point out that proteins, however, can catalyze reactions with carbon dioxide, the main greenhouse gas, in an environmentally friendly way. That fact got the scientists interested in evaluating the possibility of using proteins in carbon capture technology.

In the study, they used the pharmacophore concept to probe how the 3-dimensional structure of proteins affects their ability to bind and capture carbon dioxide. The German chemist and Nobel Laureate Paul Ehrlich, who originated the concept a century ago, defined a pharmacophore as the molecular framework that carries the key features responsible for a drug's activity. The scientists concluded that the approach could point the way to the development of next-generation carbon capture technologies.

Energy & Fuels: "Toward Greener Carbon Capture Technologies: A Pharmacore-Based Approach to Predict CO2 Binding Sites in Proteins" [Article ASAP; DOI: 10.1021/ef901132v].