Saturday, August 6, 2011

Wave Motion - New Compounds for Molecule Interferometry Experiments

When waves meet, a new single wave is created. This phenomenon is well understood for mechanical waves such as sound, and electro-magnetic waves such as light, and the "interference" of light waves is applied in astronomy, fiber optics, and oceanography. The observation that even individual large organic molecules can delocalize over large distance and interfere — not with each other, but each one with itself — is rather new, and its study requires suitable substances. A team of chemists led by Marcel Mayor at the Universität Basel has recently designed a new series of compounds that were successfully used for interferometry experiments by a group of experimental physicists headed by Markus Arndt at the Universität Wien, as they report in the European Journal of Organic Chemistry.

Chemical functionalization allows the properties of the molecules to be tailored to the needs of the experiments. To be compatible with interferometry, compounds must be highly volatile, stable, and easily ionized. In order to understand the transition between quantum and classical mechanics, it is important to study molecules of increasing mass. The first two criteria can be met by highly fluorinated compounds. To meet the requirements of a high molecular mass and good detectability, the authors judiciously paired the fluorinated moieties to a porphyrin core.

The team presented a modular synthesis of seven fluorinated porphyrins. The aim of the authors was to cover a specific mass range and to optimize the design of the structures towards high volatility; their resulting synthetic strategy is straightforward and easily applied. The fluorine components are coupled to the outer parts of the porphyrins in the last step of the synthesis. They can thus be easily modified to fine-tune the interferometry experiments. Despite the high fluorine content of the porphyrins, these compounds could still be produced by established organic synthesis protocols.

The researchers showed that at least one of their prepared compounds met the criteria for thermal evaporation and stability, and the team plans to adopt the modular synthesis technique reported for the design of more specific, mass-limited, sublimable organic dyes for future molecule interferometry experiments.

Original publication:
Marcel Mayor et al.; "Highly Fluorous Porphyrins as Model Compounds for Molecule Interferometry"; European Journal of Organic Chemistry.


Global Polyester Market to Reach Nearly 40 Million Tons

 The global polyester market is expected to achieve levels of 39.3 million tons by 2015, according to a new report available on Growth in the use of polyester in Asian countries, particularly in China is predicted to drive market expansion.

Asia-Pacific represents the largest as well as fastest growing regional polyester market. A large portion of the Asia-Pacific demand for polyester originates from China. Currently, China, with a huge installed capacity base, accounts for the majority of the world polyester market.

Asia-Pacific is poised to demonstrate the fastest CAGR of more than 6.0% over the analysis period. In terms of products, filament yarn constitutes the largest as well as fastest growing polyester product segment. Filament yarn is projected to demonstrate a CAGR of more than 5.0% over the analysis period.

Polyester plants worldwide primarily rely on continuous production systems. In recent times, newer plants are being designed with advanced four-reactor construction in place of conventional five-reactor construction so as to make the plant more economically profitable. In addition, a large number of polyester manufacturers in countries such as China, Taiwan, and other Asian countries are seen integrating backwards into fiber production. Factors including increasing demand for polyester textiles in the region and producers' desire for better control over feedstock are encouraging the manufacturers to focus on backward integration.

Major players profiled in the polyester market report include AOC, Ashland Performance Chemicals, DAK Americas LLC, Diolen Industrial Fibers, Du Pont, Far Eastern Industrial, Hyosung, Invista, Kolon Industries, Kordsa Global, Mitsubishi Chemical Corporation, Nan Ya Plastics Corporation, Performance Fibers, Reichhold, Reliance Industries, Teijin, Toray, Wellman, Zhejiang GuXianDao Industrial Fiber among others.


Seaweed as a rich new source of heart-healthy food ingredients

In an article that may bring smiles to the faces of vegetarians who consume no dairy products and vegans, who consume no animal-based foods, scientists have identified seaweed as a rich new potential source of heart-healthy food ingredients. Seaweed and other "macroalgae" could rival milk products as sources of these so-called "bioactive peptides," they conclude in an article in ACS's Journal of Agricultural and Food Chemistry.

Maria Hayes and colleagues Ciarán Fitzgerald, Eimear Gallagher and Deniz Tasdemir note increased interest in using bioactive peptides, now obtained mainly from , as ingredients in so-called functional foods. Those foods not only provide nutrition, but have a medicine-like effect in treating or preventing certain diseases. Seaweeds are a rich but neglected alternative source, they state, noting that people in East Asian and other cultures have eaten seaweed for centuries: Nori in Japan, dulse in coastal Europe, and limu palahalaha in native Hawaiian cuisine.

Their review of almost 100 scientific studies concluded that that some proteins work just like the bioactive peptides in milk products to reduce blood pressure almost like the popular ACE inhibitor drugs. "The variety of macroalga species and the environments in which they are found and their ease of cultivation make macroalgae a relatively untapped source of new bioactive compounds, and more efforts are needed to fully exploit their potential for use and delivery to consumers in food products," Hayes and her colleagues conclude.

More information: “Heart Health Peptides from Macroalgae and Their Potential Use in Functional Foods” J. Agric. Food Chem., 2011, 59 (13), pp 6829–6836 DOI: 10.1021/jf201114d

Macroalgae have for centuries been consumed whole among the East Asian populations of China, Korea, and Japan. Due to the environment in which they grow, macroalgae produce unique and interesting biologically active compounds. Protein can account for up to 47% of the dry weight of macroalgae depending on species and time of cultivation and harvest. Peptides derived from marcoalgae are proven to have hypotensive effects in the human circulatory system. Hypertension is one of the major, yet controllable, risk factors in cardiovascular disease (CVD). CVD is the main cause of death in Europe, accounting for over 4.3 million deaths each year. In the United States it affects one in three individuals. Hypotensive peptides derived from marine and other sources have already been incorporated into functional foods such as beverages and soups. The purpose of this review is to highlight the potential of heart health peptides from macroalgae and to discuss the feasibility of expanding the variety of foods these peptides may be used in.

Provided by American Chemical Society (news : web)

Chemists create molecular polyhedron

Chemists have created a molecular polyhedron, a ground-breaking assembly that has the potential to impact a range of industrial and consumer products, including magnetic and optical materials.

The work, reported in the latest issue of the journal Science, was conducted by researchers at New York University's Department of Chemistry and its Molecular Design Institute and the University of Milan's Department of .

Researchers have sought to coerce to form regular polyhedra—three-dimensional objects in which each side, or face, is a polygon—but without sustained success. Archimedean solids, discovered by the ancient Greek mathematician Archimedes, have attracted considerable attention in this regard. These 13 solids are those in which each face is a regular polygon and in which around every vertex—the corner at which its geometric shapes meet—the same polygons appear in the same sequences. For instance, in a truncated tetrahedron, the pattern forming at every vertex is hexagon-hexagon-triangle. The synthesis of such structures from molecules is an intellectual challenge.

The work by the NYU and University of Milan forms a quasi-truncated octahedron, which also constitutes one of the 13 Archimedean solids. Moreover, as a , the structure has the potential to serve as a cage-like framework to trap other molecular species, which can jointly serve as building blocks for new and enhanced materials.

"We've demonstrated how to coerce molecules to assemble into a polyhedron by design," explained Michael Ward, chair of NYU's Department of Chemistry and one of the study's co-authors. "The next step will be to expand on the work by making other polyhedra using similar design principles, which can lead to new materials with unusual properties."

The research team's creation relies on a remarkably high number of —72—to assemble two kinds of hexagonal molecular tiles, four each, into a truncated octahedron, which consists of eight molecular tiles. Although chemists often use hydrogen bonds because of their versatility in building complex structures, these bonds are weaker than those holding atoms together within the molecules themselves, which often makes larger scale structures constructed with hydrogen bonds less predictable and less sustainable. The truncated octahedron discovered by the NYU team proved to be remarkably stable, however, because the hydrogen bonds are stabilized by the ionic nature of the molecules and because no other outcomes are possible. In fact, the truncated octahedra assemble further into crystals that have nanoscale pores, resembling a class of well-known compounds called zeolites, which are made from inorganic components.

Because the structure also serves as a molecular cage, it can house, or encapsulate, other molecular components, giving future chemists a vehicle for developing a range of new compounds.

Provided by New York University (news : web)

SLAC X-rays help discover new drug against melanoma


It was front page news around the world: a drug designed to disrupt malignant melanoma, the deadliest form of skin cancer, was so successful in its latest round of testing in humans that the tests were halted – like an early-round knockout in boxing – so patients in the trial who were receiving other treatments could be moved to the new medicine.

A crucial part of the research for developing this new drug, called vemurafenib, took place at three DOE national laboratories: SLAC National Accelerator Laboratory, Argonne National Laboratory and Lawrence Berkeley National Laboratory. A Berkeley-based drug-discovery company, Plexxikon, used the labs’ powerful X-ray facilities to determine the precise structure of a mutated protein involved in this cancer – and potential drug candidates that could stop its spread.

Plexxikon’s success, reported last month, is an impressive victory for an emerging approach to combating illness: creating drugs custom-designed to throw molecular monkey wrenches into the disease process.

First researchers identify a target protein that plays a key role in the disease. In this case, it was an enzyme involved in cell growth that sometimes mutates and makes cells multiply out of control, the hallmark of cancer. If the scientists could find a small molecule that fit perfectly into a specific place in the mutated enzyme, they could block the enzyme’s action and slow or stop the cancer.

The researchers screen hundreds of small molecules – potential drugs – and identify the most promising ones. Then they bind each molecule to the target protein, crystallize the bound pair and study it with powerful beams of X-rays, which scatter off the atoms in the crystal and reveal its 3-D structure. This technique, known as macromolecular X-ray crystallography, has become an important tool for probing large, complex biological molecules and discovering new drugs. Molecules that look like good blockers are chemically tweaked to optimize their performance, and their structures determined again to see if they bind to the target protein more effectively. It may take several rounds of such chemical tinkering and X-ray structure work to find the optimal molecule for stopping the disease with no significant side effects. Drug candidates then undergo a rigorous series of highly-regulated trials to determine their effectiveness, safety, side effects and proper dosages.

Plexxikon also used the X-ray crystallography facilities at SLAC’s Stanford Synchrotron Radiation Lightsource, or SSRL, to design two other drugs that are now being tested in humans. One is aimed at type II diabetes and other metabolic disorders. The other attacks cells found in many metastatic breast, colorectal, lung, and prostate cancers, and may also be effective against autoimmune diseases such as rheumatoid arthritis, multiple sclerosis and lupus.

“Our unique success story in producing a life-changing drug in a matter of a few years is a testament to the power of structural information,” said Chao Zhang, the company’s head of structural chemistry. He said structures produced by X-ray crystallography “provide precise information on how a drug interacts with its protein target. This information points us in the most productive directions, enabling a small chemistry team to generate new drug candidates quickly.”

Macromolecular crystallography is a rapidly growing activity. Six of SSRL’s 30 beamlines host a large number of such projects each year; the specialized beam lines are funded primarily by the Department of Energy’s Office of Biological and Environmental Research and the National Institutes of Health. Worldwide, scientists are using more than 130 X-ray synchrotron beamlines to study biological molecules. X-ray crystallography was used to determine some 87 percent of the nearly 74,000 structures submitted to date to the Protein Data Bank, the worldwide repository for 3-D structure information on large biological molecules, and the vast majority of those used synchrotron X-rays.

Since scientists first demonstrated the feasibility of using synchrotron radiation for macromolecular crystallography at SSRL in 1976, greater X-ray intensity, better beam quality and improved detectors, computers and sample-handling automation have dramatically increased the speed and accuracy with which scientists can obtain their results.

“Ten years ago we could typically examine only 20 crystals per 8-hour shift on a beamline, and collect data from one or two of them,” said Ana Gonzalez, SSRL senior staff scientist. Now, she said, users can manipulate their samples and measure the data remotely, over the Internet, “and during a single shift we can look at some 100 crystals and also collect datasets from 20 to 30 of them.”

The future offers potentially transformative new technologies thanks to SLAC’s Linac Coherent Light Source, or LCLS. In experiments there, an international team of scientists showed that they can get the rough 3-D structures of proteins from tiny protein nanocrystals, which may be much easier to create than the larger crystals needed for traditional synchrotron-based X-ray diffraction. The nanocrystals are suspended in water and squirted through the powerful LCLS X-ray laser beam, which pulses 120 times a second. In the instant before the intense X-rays destroy a nanocrystal, detectors record a flash of X-ray diffraction information. Finally, scientists use sophisticated computer programs to merge the data from hundreds of thousands of nanocrystals to reveal the protein’s structure.

By enabling scientists to determine the structures of many proteins that don’t fully crystallize, “the ultrafast LCLS X-ray beam has the potential to guide the design of next-generation drugs,” said Plexxikon’s Zhang.

Provided by SLAC National Accelerator Laboratory (news : web)