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American Chemical Society's Weekly PressPac -- July 30, 2008


New imaging technique reveals hidden details of a lost Van Gogh painting
Analytical Chemistry

European researchers are reporting the first use of a powerful new imaging technique to reveal with unprecedented detail a Van Gogh under a Van Gogh the portrait of a woman hidden underneath one of the fabled Dutch Master's landscapes. Their study, which could provide new insights into the hidden details of other paintings, was scheduled for the July 29 online issue of ACS' Analytical Chemistry, a bi-weekly publication.

Joris Dik and colleagues note that Vincent van Gogh, one of the founding fathers of modern painting, saved canvas by painting-over as many as one-third of his early period works with new or modified pictures. However, current imaging tools used by museums are unable to clearly visualize many of these hidden images, which offer unique and intimate insights into the artist's works, the researchers say.

In the new study, the researchers used their new non-destructive technique, called Synchrotron Radiation-based X-Ray Fluorescence (XRF) Elemental Mapping, to analyze Van Gogh's Patch of Grass painting. Although conventional imaging techniques previously showed that the painting contained the hidden image of a woman's head, the details were blurred. The new technique reveals more detailed information about the chemical composition of the hidden paint layers. As a result, the scientists could construct a clearer and more colorful image of the hidden head. The image even includes brush strokes and facial features such as eyes, nose, mouth, and chin. The reconstructed image shows the dark, somber-head of a Dutch peasant woman, similar to a series of head portraits from Van Gogh's early career, the researchers say. MTS

"A Lost Painting by Vincent van Gogh Visualized by Synchrotron Radiation-based XRF Elemental Mapping"


Joris Dik, Ph.D.
Delft University of Technology
Delft, The Netherlands
Phone: 31-15-2789571


Keeping the crunch in the crust
Journal of Agricultural and Food Chemistry

Scientists in the Netherlands report an advance toward unraveling one of the culinary world's long-standing puzzles: How to maintain the crispy quality of bread crust. The findings could help prolong the coveted crunchiness of bagels, French bread, and other bakery products, the researchers say. Their findings are scheduled for two reports in the August 13 issue of the ACS' bi-weekly Journal of Agricultural and Food Chemistry.

In the new study, Neleke van Nieuwenhuijzen, Marcel Meinders, Ton van Vliet, and colleagues point out that scientists have known for years that dry bread crust starts losing its crispness when water migrates into the crust, resulting in a perceived loss of freshness that turns off consumers. Details of the mechanisms involved in this effect, however, have remained a mystery until now.

The scientists baked wheat bread under different moisture conditions, vapor pressures, and temperatures and then studied the water content and texture of the resulting crusts using sensitive laboratory instruments. They found that water content and water movement in the bread during and after baking were the key factors that determine the crispness of crusts and its retention. By modifying these factors, bakers can optimize bread ingredients to produce crisper, longer-lasting crusts, the researchers say. MTS

"Water Content or Water Activity: What Rules Crispy Behavior in Bread Crust?"
"Water Uptake Mechanism in Crispy Bread Crust"


Marcel Meinders, Ph.D.
Ton van Vliet, Ph.D.
TI Food and Nutrition (formerly WCFS)
Wageningen, the Netherlands
Phone: 0031 317 475 215 (Meinders)
0031-317-475347 (Van Vliet)


Perfectly proportioned legs keep water striders striding

The amazing water strider known for its ability to walk on water came within just a hair of sinking into evolutionary oblivion. Scientists in France and the United Kingdom are reporting that the insect's long, flexible legs have an optimal length that keeps it afloat. Their report is scheduled for the August 19 issue of ACS' Langmuir, a bi-weekly journal.

In the new study, Dominic Vella notes that scientists already know much about the water-repellant structure of the water strider's legs and how it allows them to efficiently scoot and jump on ponds and lakes. However, the insect's many adaptations to life on water surfaces pose scientific puzzles. Solving those mysteries may have practical applications in the design of water-walking robots that can support the maximum possible payload, they note.

Building on earlier work by scientists at Carnegie Mellon University, Vella developed a mathematical model to determine the maximum weight load that a thin, flexible cylinder representing a water strider's legs can support on a liquid surface without sinking. He found that as the length of the cylinder increases, the maximum load at first increases but then reaches a plateau at some critical length. After that length, the cylinder begins to bend and is not able to support more weight. Comparing the model to measurements on museum specimens, Vella found that the strider's legs are typically slightly shorter than the critical length. This suggests that the water strider's legs are just the right length: Long enough to provide maximum weight support but not long enough to bend and hinder the insect's movement, he says. MTS

"Floating Objects with Finite Resistance to Bending"


Dominic Vella, Ph.D.
University of Cambridge
United Kingdom


Turning those old electronic circuit boards into new park benches
Environmental Science & Technology

Scientists in China have developed a new recycling method that could transform yesterday's computer into tomorrow's park bench. Their study, which focuses on decreasing environmental pollution through resource preservation, reuses fibers and resins of waste printed circuit boards (PCBs) that were thought worthless to produce a variety of high-strength materials. It is in the July 15 issue of Environmental Science & Technology.

Zhenming Xu and colleagues point out that as more electrical and electronic equipment has become obsolete, the issue of electronic-waste removal has intensified. PCBs account for about 3 percent by weight of all electronic waste, Xu says. Although metals from the circuit boards, such as copper and aluminum, are recycled, landfill disposal has been the primary method for treating their nonmetallic materials, which have been difficult to recycle, the paper says.

In the study, the researchers developed a process to recycle those nonmetallic materials, which they say could be used to produce diverse items like sewer grates, park benches and fences. The recycled material could also be a substitute for wood and other materials since it is almost as strong as reinforced concrete. "There is no doubt that the technique has potential in the industry for recycling nonmetallic materials of PCBs," Xu says. JS

"A Plate Produced by Nonmetallic Materials of Pulverized Waste Printed Circuit Boards"


Zhenming Xu, Ph.D.
Shanghai Jiao Tong University
Shanghai, China
Phone: +86 21 54747495
Fax: +86 21 54747495


"Chiral" molecules pave the way for safer, more effective drugs
Chemical & Engineering News

In the drive to create safer, more effective drugs for cancer, Parkinson's disease, and other health challenges, researchers worldwide are stepping up efforts to produce purer substances based on a molecule's unique symmetry or chirality, according to an article scheduled for the August 4 issue of Chemical & Engineering News.

In the C&EN cover story, Senior Correspondent Ann M. Thayer points out that in the pharmaceutical world, a molecule's right- or left-handed symmetry determines whether it does good or ill in the body. Today, about 70 percent of new small-molecule drugs that the Food & Drug Administration approved in 2007 contained at least one chiral molecule as its central active component.

But creating one specific configuration of mirror image molecules rather than a mixture remains a challenge, as these molecules are complex and difficult for chemists to construct. But thanks to increased cooperation between academia and industry, chemists are identifying new catalysts and reactions to produce chiral compounds faster, more efficiently, and with fewer environmental risks, such as metal contaminants, the article notes. Although these processes will likely remain unknown to the average consumer, health and the environment will benefit in the long run, the article suggests.

"Interaction Yields"

This story will be available on August 4 at

Michael Bernstein
ACS News Service
Phone: 202-872-6042
Fax: 202-872-4370


Contact: Michael Woods
American Chemical Society

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