Chemistry News Archive May 2008

Melting glaciers may release DDT and contaminate Antarctic environment

In an unexpected consequence of climate change, scientists are raising the possibility that glacial melting is releasing large amounts of the banned pesticide DDT, which is contaminating the environment in Antarctica. The study is scheduled for the June 1 issue of ACS� bi-weekly journal Environmental Science & Technology.

In the study, Heidi N. Geisz and colleagues estimate that up to 2.0-8.8 pounds of DDT are released into coastal waters annually along the Western Antarctic Ice Sheet from glacial meltwater. The researchers point out that DDT reaches Antarctica by long-range atmospheric transport in snow, and then gets concentrated in the food chain. DDT has been banned in the northern hemisphere and has been regulated worldwide since the 1970s. Geisz found, however, that DDT levels in the Adelie penguin have been unchanged since the 1970s, despite an 80 percent reduction in global use.

Global warming may explain that contradiction, they say. As the annual winter temperature on the Antarctic Peninsula has increased by about 10 degrees Fahrenheit in the last 30 years, glaciers have retreated. The possibility that glacial meltwater has contaminated Antarctic organisms with DDT, the study says, �has compelling consequences� if global warming should continue and intensify. - JS

Environmental Science & Technology: "Melting Glaciers: A Probable Source of DDT to the Antarctic Marine Ecosystem".

Light-driven "molecular brakes" provide stopping power for nanomachines

Researchers in Taiwan report development of a new type of "molecular brake" that could provide on-demand stopping power for futuristic nanomachines. The brake, thousands of times smaller than the width of a human hair, is powered by light and is the first capable of working at room temperature, the researchers say. Their study is scheduled for the June 5 issue of ACS' Organic Letters, a bi-weekly journal.

In the new study, Jye-Shane Yang and colleagues point out that the ability to control specific motions of small molecules or larger molecular structures is essential for the development of nanomachines. Some of these machines may find use in delivering drugs or performing surgery deep inside the human body. Although scientists have already built molecular motors, wheels, and gears for powering nanomachines, the development of a practical braking system remains a challenge, the researchers say.

Yang�s group assembled a prototype molecular brake that resembles a tiny four-bladed wheel and contains light-sensitive molecules. The paddle-like structure spins freely when a nanomachine is in motion. In laboratory studies, the scientists showed that exposing the structure to light changes its shape so that "blades" stop spinning, putting on the brakes. The braking power can be turned off by altering the wavelength of light exposure, they add. - MTS

Organic Letters: "A Pentiptycene-Derived Light-Driven Molecular Brake".

Next-generation explosives: More power and safety without the pollution

Scientists in Germany are reporting development of a new generation of explosives that is more powerful than TNT and other existing explosives, less apt to detonate accidentally, and produce fewer toxic byproducts. Their study of these more environmentally friendly explosives is scheduled for the June 24 issue of ACS� Chemistry of Materials, a bi-weekly journal.

In the new study, Thomas M. Klap�tke and Carles Mir� Sabate point out that conventional explosives such as TNT, RDX and HMX, widely-used in military weapons, are rich in carbon and tend to produce toxic gases upon ignition. In addition to polluting the environment, these materials are also highly sensitive to physical shock, such as hard impacts and electric sparks, making their handling extremely dangerous. Greener, safer explosives are needed, the researchers say.

To meet this need, Klap�tke and Sabate turned to a recently explored class of materials called tetrazoles, which derive most of their explosive energy from nitrogen instead of carbon. They identified two promising tetrazoles: HBT and G2ZT. The researchers developed tiny �bombs� out of these materials and detonated them in the laboratory. The materials showed less sensitivity to shock than conventional explosives and produced fewer toxic products when burned, the researchers say. - MTS

Chemistry of Materials: "Bistetrazoles: Nitrogen-Rich, High-Performing, Insensitive Energetic Compounds".

Rice in your gas tank: Boosting biofuel production from rice straw

Researchers in China are reporting a discovery that could turn rice straw into an inexpensive new renewable source of biofuel. Their new study, scheduled for the July 16 issue of ACS' bimonthly journal Energy & Fuels, describes a way to boost production of biofuel from rice straw by almost 65 percent.

In the new study, Xiujin Li and colleagues point out that China is the world's largest rice producer, a crop that leaves behind about 230 million tons of rice straw each year. Rice straw is the stem and leaves left behind after harvesting the grains. Scientists, however, have not tapped rice straw for production of biogas because bacteria cannot easily break down its cellulose due to the complex physical and chemical structures of lignocellulosic biomass.

The researchers treated rice straw with sodium hydroxide before allowing bacteria to ferment it into a biogas. That so-called pretreatment increased biogas production by making more cellulose and other compositions in straw available for digestion by the bacteria. Three prototype facilities have been built in China using this technology. - MTS

Energy & Fuels:
"Physiochemical Characterization of Rice Straw Pretreated with Sodium Hydroxide in the Solid State for Enhancing Biogas Production".

Electronic waste disposal: A growing challenge

Millions of tons of unwanted computers, cell phones and other electronic waste (E-waste) are filling the world�s recycling bins each year. But the lack of standardized recycling methods and E-waste�s potentially toxic health effects have sparked a growing debate over how to deal with this tsunami of cast-off technology, according to an article scheduled for the May 26 issue of Chemical & Engineering News, ACS� weekly newsmagazine.

C&EN Senior Editor Jeff Johnson points out that barely 15 percent of the estimated two million tons of E-waste produced each year in the United States is recycled or reused. Leftovers are often shipped to poorer countries like Africa, India, or China, where workers face health dangers as they attempt to remove lesser valued, more toxic parts, the article notes.

But change may be around the corner. Environmental advocates, community groups, Congress, and some in the electronics industry are seeking alternatives to these �informal� recycling efforts, including the manufacture of �greener� electronic parts and equipment, tougher regulations on the disposal and shipping of E-waste, and �take back� programs that encourage manufacturers to collect the E-waste that they produce, according to the article.

Chemical & Engineering News: "A Tsunami of Electronic Waste".

New-generation artificial cornea could restore vision for millions worldwide

An improved artificial cornea, which could restore the vision of more than 10 million people worldwide who are blind due to diseased corneas, finally is moving toward reality, scientists in California conclude in a new analysis of research on the topic. Their study is scheduled for the June 6 issue of ACS' Biotechnology Progress, a bi-monthly journal.

Curtis Frank, Christopher Ta, David Myung, and Jennifer Cochran point out that disease or injury to the cornea - the clear tissue covering the front of the eye - is the second leading cause of blindness worldwide. Although treated in developed countries with transplants from donors, cornea transplants are unavailable in many parts of the world due to shortages of donors or to cultural or religious barriers. The growing popularity of laser eye surgery also is reducing availability of corneas by making them unacceptable for donation, the researchers add.

The report describes new materials that already have made limited-use artificial corneas available, partially fulfilling a medical dream that dates to 1771. More advanced materials, including polymer hydrogels similar to those used to make soft contact lenses, promise to so closely imitate human donor corneas that �these devices could eliminate the need for donor corneas altogether,� the article notes. - MTS

Biotechnology Progress: "Development of Hydrogel-Based Keratoprostheses: A Materials Perspective".

First evidence that bacteria get �touchy-feely� about dangerous biofilms

Researchers in Massachusetts report for the first time that bacteria use a sense of touch in deciding where to form biofilms. Those colonies of microbes grow on medical implants and other devices and play a key role in the multi-billion-dollar-per-year problem of antibiotic resistant infections. The finding could lead to safer implant materials for fighting biofilms, which are linked to thousands of deaths each year, the scientists say. It also can be used to develop materials capable of sustaining cultures of important, beneficial bacteria. Their study is scheduled for the June 9 issue of ACS� Biomacromolecules, a bi-monthly journal.

In the new report, Krystyn J. Van Vliet and colleagues note that past research focused on killing microbes that already have formed biofilms, or impregnating surfaces with antimicrobial compounds. Scientists knew about certain surface conditions that affected biofilm formation, though many results were in conflict, and the effect of mechanical stiffness of those surfaces had not been considered previously.

The researchers studied the effects of different polymer materials on the adhesion of Staphylococcus epidermidis, the most common bacterial source of hospital-based infections, and on E. coli. In laboratory tests, they found that the bacteria adhered preferentially to the stiffer polymers, as compared to other polymers. Altering the stiffness of the polymers used in implants could lead to �smarter� materials for fighting or sustaining biofilm formation, they conclude. - MTS

Biomacromolecules: "Substrata Mechanical Stiffness Can Regulate Adhesion of Viable Bacteria".

Rice grown in United States contains less-dangerous form of arsenic

Rice grown in the United States may be safer than varieties from Asia and Europe, according to a new global study of the grain that feeds over half of humanity. The study evaluated levels of arsenic, which can be toxic at high levels, in rice worldwide. The two-part report is scheduled for the May 15 issue of ACS� Environmental Science & Technology, a semi-monthly journal.

Yamily J. Zavala and colleagues point out that rice is a potentially important source of human exposure to arsenic, especially in populations with rice-based diets. Arsenic in rice is of special concern because it accumulates in much higher concentrations in rice than other staple grain crops. The researchers discovered that arsenic contamination of irrigation water was more important than soil contamination in increasing arsenic levels in rice.

Using global arsenic data, the researchers classified rice into two types, where the predominant arsenic forms were either organic or the more toxic inorganic forms. They found that rice from the United States largely contains organic arsenic, which is less easily absorbed into the body and excreted more rapidly than inorganic arsenic. Rice contaminated with inorganic arsenic prevails in Asia and Europe. The study suggests that breeding new rice varieties that convert inorganic arsenic to organic arsenic would be an �important risk reduction strategy, especially for countries like Bangladesh and India with arsenic contaminated environments and high rice consumption rates.� - AD

Environmental Science & Technology:
- "Arsenic in Rice: I. Estimating Normal Levels of Total Arsenic in Rice Grain",
- "Arsenic in Rice: II. Arsenic Speciation in USA Grain and Implications for Human Health".

A simple, low-cost carbon filter removes 90% of carbon dioxide from smokestack gases

Researchers in Wyoming report development of a low-cost carbon filter that can remove 90 percent of carbon dioxide gas from the smokestacks of electric power plants that burn coal and other fossil fuels. Their study is scheduled for the May 21 issue of ACS� monthly journal, Industrial & Engineering Chemistry Research.

Maciej Radosz and colleagues at Wyoming's Soft Materials Laboratory cite the pressing need for simple, inexpensive new technologies to remove carbon dioxide from smokestack gases. Coal-burning electric power plants are major sources of the greenhouse gas, and control measures may be required in the future.

The study describes a new carbon dioxide-capture process, called a Carbon Filter Process, designed to meet the need. It uses a simple, low-cost filter filled with porous carbonaceous sorbent that works at low pressures. Modeling data and laboratory tests suggest that the device works better than existing technologies at a fraction of their cost. - MTS

Industrial & Engineering Chemistry Research: "Flue-Gas Carbon Capture on Carbonaceous Sorbents: Toward a Low-Cost Multifunctional Carbon Filter for �Green� Energy Producers".

Dirt-digging Mars spacecraft to look for evidence of life beneath planet�s surface

With the scheduled landing of the Phoenix spacecraft on the surface of Mar�s later this month, scientists are hoping that the craft will provide new chemical clues about the red planet�s watery past or even the presence of life. If successful, the mission will be the first to dig beneath the planet�s surface, according to an article scheduled for the May 19 issue of Chemical & Engineering News, ACS� weekly newsmagazine.

Written by Senior Editor Elizabeth K. Wilson, the C&EN article notes that several space vehicles have explored Mars over the past few years, providing valuable information about its surface rocks and atmosphere. But many scientists believe that if life exists or ever existed on the planet, the chemical clues for its existence are likely found in the soil beneath the surface. Scheduled to land May 25, the Phoenix spacecraft is equipped with four sensor-laden �beakers� to test sub-surface soil samples dug by the craft�s robotic arm.

The lander�s destination is a flat plain near Mar�s north pole, where NASA�s Mars Odyssey orbiter recently detected evidence of subsurface water and ice. At the very least, scientists hope to finally solve the long-standing mystery of the exact chemical composition of the Martian soil. A manned mission may be next, the article notes, though not anytime soon.

Chemical & Engineering News: "Digging beneath the Martian surface".

Identifying abnormal protein levels in diabetic retinopathy

Researchers in Massachusetts are reporting an advance in bridging huge gaps in medical knowledge about the biochemical changes that occur inside the eyes of individuals with diabetic retinopathy (DR) - a leading cause of vision loss and blindness in adults. In a study scheduled for the June 6 issue of ACS� monthly Journal of Proteome Research, they report discovery of 37 proteins that were increased or decreased in the eyes of patients with DR compared to patients without the disease.

Edward P. Feener and colleagues point out that DR is a complication of diabetes that affects the eyesight of millions of people. It involves damage to blood vessels in the retina, the light sensitive tissue in the back of the eye. Physicians know that vessels grow abnormally, swell, and leak in DR. However, they have little understanding of the biochemical changes underlying those damaging events.

The researchers studied eye fluid from individuals with and without DR who were undergoing eye surgery. They analyzed proteins in the vitreous, the gel-like material inside the eye between the retina and the lens. The study found 252 proteins in the fluid, including 37 proteins that showed changes that were associated with proliferative diabetic retinopathy, the most severe form of the disease. The study could lead to new insights into disease mechanisms and new treatments, the article states. - MTS

Journal of Proteome Research: "Characterization of the Vitreous Proteome in Diabetes without Diabetic Retinopathy and Diabetes with Proliferative Diabetic Retinopathy".

Microwave zapping kills invasive species before the invasion

Scientists in Louisiana are reporting development and successful testing of a new cost-effective system to kill unwanted plants and animals that hitch a ride to the United States in the ballast water of merchant ships. These so-called �invasive species,� such as the notorious zebra mussel, devastate native organisms and infrastructure and cost taxpayers billions of dollars annually. The study is scheduled for the June 1 issue of ACS� Environmental Science & Technology, a semi-monthly journal.

In the study, Dorin Boldor and colleagues point out that invasive species often travel in ballast tanks of international cargo ships. Ships pump sea water into these tanks for stability when a vessel leaves port with little or no cargo. They dump the water at their destination - along with zebra mussels, Asian clams and other organisms that may pose environmental risks.

The new study describes development and laboratory-scale tests of a continuous microwave system which, much like a kitchen microwave oven, used heat to inactivate zooplankton, algae, and oyster larvae in salt water. Researchers found that a 30-second zap, followed by a 200-second holding period, removed all marine life. Boldor noted that the high heating rates, low operating costs, and effectiveness in hazy water distinguish it from conventional heating methods. - JS

Environmental Science & Technology: "Design and Implementation of a Continuous Microwave Heating System for Ballast Water Treatment".

New process may convert toxic computer waste into safe products

Discarded computer parts could one day wind up fueling your car. That�s because researchers in Romania and Turkey have developed a simple, efficient method for recycling printed circuit boards into environmentally-friendly raw materials for use in fuel, plastic, and other useful consumer products. Their study is scheduled for the May 21 issue of ACS� Energy & Fuels, a bi-monthly journal.

The boom in the use of computers has also created one of the world�s biggest environmental headaches: What to do with all the discarded circuit boards, which contain high levels of pollutants such as heavy metals and flame retardants that can potentially harm humans? Researchers are seeking ways to remove these toxins so that these scrap materials can be safely recycled.

In the new study, Cornelia Vasile and colleagues collected printed circuit boards from discarded computers and processed the boards with a combination of high temperatures, catalysts, and chemical filtration. The processing method removed almost all of the toxic substances from the scraps, resulting in oils that can be safely used as fuel or raw materials called feedstocks for a wide variety of consumer products, the researchers say. - MTS

Energy & Fuels: "Feedstock Recycling from the Printed Circuit Boards of Used Computers".

Consumers warm up to �greener� personal care products, but labeling controversy broils

From soaps to body lotions to shampoos, consumers are increasingly drawn to personal care products that are labeled �green� or environmentally-friendly, a fast-growing market that chalks-up an estimated $4 billion in sales per year worldwide. Despite the hype over these products, there�s growing confusion by consumers and manufacturers alike over what it really means to be labeled as �green,� according to an article scheduled for the May 12 issue of Chemical & Engineering News, ACS� weekly newsmagazine.

Written by C&EN Senior Correspondent Marc Reisch, the magazine�s cover story points out that there�s no universal consensus over what is green, organic, or sustainable. To the detriment of consumers, manufacturers sometimes produce misleading labels in an effort to cash-in on the hype, the article notes. Some manufacturers have even begun to certify their products as green under a variety of different standards and criteria or using different certifying bodies.

But change may be around the corner. Some groups in the U.S. and abroad are now working on establishing clearer standards for personal care products. Notes Reisch: �Unless ingredient makers and formulators sort out their differences, the subject of what is natural, organic, and sustainable may have to be sorted out in a court of law.�

Chemical & Engineering News: "Seeking Sustainability".

Fighting global warming - at the dinner table

Substituting chicken, fish, or vegetables for red meat just once a week can help combat climate change - even more dramatically than buying locally sourced food, according to scientists in Pennsylvania who studied the environmental impacts of food production and distribution in the United States. The study is scheduled for the May 15 issue of ACS�s bi-weekly journal Environmental Science & Technology.

In the study, Christopher L. Weber and H. Scott Matthews explain that environmental advocates and retailers have urged customers to purchase goods from local sources to minimize environmental impacts. Despite this emphasis on �buying local,� the researchers point out that few studies in the U. S. have compared greenhouse gas emissions from food production to those of transportation.

Weber and Matthews found that the production phase dominates the average U.S. household�s greenhouse-gas burden - contributing 83 percent of them - whereas transportation accounts for only 11 percent. Red meat, according to the report, is almost 150 percent more greenhouse-gas-intensive than chicken or fish.

�Thus, we suggest that dietary shift can be a more effective means of lowering an average household�s food-related climate footprint than �buying local,�� the paper says. �Shifting less than one day per week�s worth of calories from red meat and dairy products to chicken, fish, eggs, or a vegetable-based diet achieves more greenhouse-gas reduction than buying all locally sourced food.� - JS

Environmental Science & Technology: "Food-Miles and the Relative Climate Impacts of Food Choices in the United States".

New insights on link between early consumption of cows� milk and Type-1 diabetes

Researchers in Maine report a new explanation for the mysterious link between consumption of cows� milk protein in infant formula early in life and an increased risk of later developing Type-1 diabetes. A protein in cow�s milk that triggers an unusual immune response appears to be the main culprit, they say. The study is scheduled for the June 6 issue of ACS� monthly Journal of Proteome Research.

In the new study, Marcia F. Goldfarb points out that several studies have reported a possible link between the early introduction of cow�s milk protein into an infant�s diet and subsequent development of the disease. In Type-1 diabetes, the immune system erroneously appears to attack and destroy insulin-producing cells in the pancreas. It usually begins in childhood, requires insulin injections, and afflicts about 800,000 people in the U.S. alone. Scientists do not understand the link between cow�s milk and diabetes. They know, however, that beta-lactoglobulin, a protein present in cow�s milk but not found in human breast-milk, is structurally similar to the human protein glycodelin, which controls the production of T-cells. T-cells help guard the body against infection.

Goldfarb describes research on patients with Type-1 diabetes, which suggests that an infant�s immature immune system may inadvertently destroy glycodelin in an effort to destroy the similar cow�s milk protein, which the system recognizes as foreign. This could result in the overproduction of T-cells, which can attack the insulin-producing cells of the pancreas and trigger diabetes, she says. - MTS

Journal of Proteome Research: "Relation of Time of Introduction of Cow Milk Protein to an Infant and Risk of Type-1 Diabetes Mellitus".

Boosting �mussel� power: New technique for making key marine mussel protein

Researchers in Korea report development of a way to double production of a sticky protein from marine mussels destined for use as an antibacterial coating to prevent life-threatening infections in medical implants. The coating, produced by genetically-engineered bacteria, could cut medical costs and improve implant safety, the researchers say. Their study is scheduled for the June 6 issue of ACS� Biotechnology Progress, a bi-monthly publication.

Bacterial infection of medical implants, such as cardiac stents and dialysis tubing, threatens thousands of people each year and is a major medical challenge due to the emergence of antibiotic-resistant bacteria. Several research groups are working on long-lasting, germ-fighting coatings from mussel proteins, but production of these coatings is inefficient and expensive.

Hyung Joon Cha and colleagues previously developed a way to use genetically engineered E. coli bacteria to produce mussel adhesive proteins. Now they report adding a new gene for producing Vitreoscilla hemoglobin (VHb), a substance that boosts production of proteins under low-oxygen conditions. Adding the VHb gene to the engineered E. coli doubled the amount of mussel proteins produced, which could lead to more cost-effective coatings, the researchers say. - MTS

Biotechnology Progress: "Enhancement of Mussel Adhesive Protein Production in Escherichia coli by Co-expression of Bacterial Hemoglobin".

Munch-o-matic: Scientists develop the artificial mouth

For years scientists have tried to build an electronic tongue, a robotic tasting device that could have profound applications in improving food quality and safety. But before machines learn to taste their food, they first need to learn how to chew it. In a study scheduled for the May 14 issue of ACS� bi-weekly Journal of Agricultural and Food Chemistry, scientists report the design of an artificial mouth that mimics the first vital steps of human digestion - chewing, saliva release and the initial breakdown of food.

In the study, Ga�lle Arvisenet and colleagues point out that a number of factors are involved in the release of aromatic and flavor compounds in the mouth. Chewing, the release of saliva, the rate of food breakdown and the temperature all affect the flavor and smell of food before it�s swallowed. To accurately reproduce the effects of chewing, Arvisenet's team needed to build a machine that could imitate several - if not all - of these subtle processes. �Our aim was not to reproduce the human mouth conditions exactly, but to reproduce the result of mastication,� says Arvisenet.

The researchers compared apples chewed by their machine and by human mouths. The resulting apple pulp was scrutinized for texture, color and aromatic compound release. �Experimental conditions were determined that produced fruit in a state closest to that obtained after mastication in a human mouth,� reports Arvisenet. - AD

Journal of Agricultural and Food Chemistry: "Effect of Apple Particle State on the Release of Volatile Compounds in a New Artificial Mouth Device".

No more needles: Toward an artificial pancreas for fighting diabetes

A specially coated metal tube, no larger than a cigarette, could be the key to developing an artificial pancreas to help millions of people with diabetes avoid insulin injections, according to an article scheduled for the May 5, 2008 issue of Chemical & Engineering News, ACS� weekly newsmagazine. The so-called �bioartificial pancreas� also could help keep blood sugar closer to normal levels, and perhaps reduce the risk of diabetic complications, which include blindness, kidney failure, and premature death, the article suggests.

Written by Associate Editor Bethany Halford, the C&EN article points out that researchers have been trying to develop an artificial pancreas for years. Most approaches involve encapsulating healthy islet cells - the pancreatic cells that detect glucose and release insulin - and transplanting them into diabetic patients. But enclosing a large collection of cells has been difficult because the materials designed to hold them are not biocompatible, or optimal for use in the body, Halford notes.

The new device, developed by Joseph P. Kennedy and colleagues at the University of Akron in Ohio, is coated with a permeable polymer membrane that is key to its success. In addition to improving the exchange of insulin and glucose between the islet cells and the blood, the polymer membrane helps increase the supply of oxygen to the cells for improved function and lifespan. The device itself has already shown promise in preliminary animal studies and researchers are looking ahead to clinical trials in humans, the article notes.

Chemical & Engineering News: "Perfecting an artificial pancreas".