Exotic quantum crystal exists: Researchers discover novel state of crystal matter

Nature knows two opposite types of solids: one that emerges upon compression from a liquid and a second that appears if the pressure on a liquid is reduced. While the former is typical for substances in our everyday life the latter occurs for example in a dense quantum liquid of electrons (such as in metals) or ions (in exotic white dwarf or neutron stars).

Now it has been shown that there exists yet a third form of matter that inherits both of these properties. This unusual behaviour has been predicted to exist in crystals of excitons -- hydrogen atom-like bound states of electrons and holes -- in a semiconductor quantum well placed in a strong electric field.

A team from Kiel University (Germany) consisting of Dr. Jens Bönning, Privatdozent Alexei Filinov and Prof. Michael Bonitz has performed extensive accurate computer simulations that shed light on the mysterious properties of this material.

The results appear in the current issue of Physical Review B. There the authors present a simple explanation for the coexistence of the two seemingly contradicting melting behaviours.

The secret lies in the character of the forces acting between two excitons: at low pressure excitons repel each other via a dipole force and form a quantum liquid. Upon compression this fluid freezes into an exciton crystal. Further compression brings two excitons so close together that the quantum wave nature of their constituents (electrons and holes) starts to weaken the forces. As a consequence, further compression leads to an increasing overlap of the exciton quantum waves that is no longer balanced by the inter-exciton repulsion, and the crystal melts again.

The researchers have made precise predictions where to search for this exotic crystal of excitons (particularly well suited are zinc selenide or gallium arsenide quantum wells) -- it is now up to the experimentalists to find this new state of matter.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by Kiel University.

Journal Reference:

J. Böning, A. Filinov, M. Bonitz. Crystallization of an exciton superfluid. Physical Review B, 2011; 84 (7) DOI: 10.1103/PhysRevB.84.075130

E. coli metabolism reversed for speedy production of fuels, chemicals

In a biotechnological tour de force, Rice University engineering researchers this week unveiled a new method for rapidly converting simple glucose into biofuels and petrochemical substitutes. In a paper published online in Nature, Rice's team described how it reversed one of the most efficient of all metabolic pathways -- the beta oxidation cycle -- to engineer bacteria that produce biofuel at a breakneck pace.

Just how fast are Rice's single-celled chemical factories? On a cell-per-cell basis, the bacteria produced the butanol, a biofuel that can be substituted for gasoline in most engines, about 10 times faster than any previously reported organism.

"That's really not even a fair comparison because the other organisms used an expensive, enriched feedstock, and we used the cheapest thing you can imagine, just glucose and mineral salts," said Ramon Gonzalez, associate professor of chemical and biomolecular engineering at Rice and lead co-author of the Nature study.

Gonzalez's laboratory is in a race with hundreds of labs around the world to find green methods for producing chemicals like butanol that have historically come from petroleum.

"We call these 'drop-in' fuels and chemicals, because their structure and properties are very similar, sometimes identical, to petroleum-based products," he said. "That means they can be 'dropped in,' or substituted, for products that are produced today by the petrochemical industry."

Butanol is a relatively short molecule, with a backbone of just four carbon atoms. Molecules with longer carbon chains have been even more troublesome for biotech producers to make, particularly molecules with chains of 10 or more carbon atoms. Gonzalez said that's partly because researchers have focused on ramping up the natural metabolic processes that cells use to build long-chain fatty acids. Gonzalez and students Clementina Dellomonaco, James Clomburg and Elliot Miller took a completely different approach.

"Rather than going with the process nature uses to build fatty acids, we reversed the process that it uses to break them apart," Gonzalez said. "It's definitely unconventional, but it makes sense because the routes nature has selected to build fatty acids are very inefficient compared with the reversal of the route it uses to break them apart."

The beta oxidation process is one of biology's most fundamental, Gonzalez said. Species ranging from single-celled bacteria to human beings use beta oxidation to break down fatty acids and generate energy.

In the Nature study, Gonzalez's team reversed the beta oxidation cycle by selectively manipulating about a dozen genes in the bacteria Escherichia coli. They also showed that selective manipulations of particular genes could be used to produce fatty acids of particular lengths, including long-chain molecules like stearic acid and palmitic acid, which have chains of more than a dozen carbon atoms.

"This is not a one-trick pony," Gonzalez said. "We can make many kinds of specialized molecules for many different markets. We can also do this in any organism. Some producers prefer to use industrial organisms other than E. coli, like algae or yeast. That's another advantage of using reverse-beta oxidation, because the pathway is present in almost every organism."

Provided by Rice University (news : web)

DuPont delivers strong results in second quarter

 DuPont’s second-quarter 2011 earnings were $1.37 per share, up 17 percent versus $1.17 per share in the prior year, excluding significant items from both periods. Reported second-quarter 2011 earnings were $1.29 per share, including significant item charges of $.08 per share related to the acquisition. Reported second-quarter 2010 earnings were $1.26 per share. Sales increased 19 percent to $10.3 billion with 11 percent higher local prices, 2 percent higher sales volume, 3 percent currency benefit and a 3 percent net increase from portfolio changes. Sales in developing markets grew 29 percent and represent 30 percent of total sales.

Strong performances in Agriculture, Performance Chemicals and Safety & Protection, and the acquisition of Danisco contributed to a 20 percent increase in segment pre-tax operating income, excluding significant items.  The company is on track versus its full-year 2011 productivity targets for fixed costs and working capital.  Year-to-date fixed cost productivity totals more than $180 million.

“Our strong second-quarter sales growth across all segments and regions resulted from consistent global execution and customer-focused innovation,” said DuPont Chair and CEO Ellen Kullman.  “We are increasing our earnings outlook for 2011 based on strong performance year–to-date and confidence in our business plans for the second half of the year.  Longer term, we expect additional compelling growth opportunities across our businesses stemming from science-powered innovations and collaboration, including the integration of Danisco’s world-class enzymes, fermentation and specialty food ingredients capabilities with DuPont’s strong industrial biosciences and nutrition & health offerings.”

The company increased its full-year 2011 earnings outlook, excluding significant items, to a range of $3.90 to $4.05 per share.  The increase reflects strong second-quarter results, the expectation for continued global economic growth and about $.05 per share full-year operating earnings from Danisco on an underlying basis. Prior guidance was a range of $3.65 to $3.85 per share, excluding the impact of Danisco.  The company’s estimate for the impact of the Danisco acquisition on full-year reported earnings is now a reduction of $.18 to $.29 per share, versus the previous estimate of a $.30 to $.45 per share reduction. The current view is based on anticipated full-year Danisco operating earnings of about $.05 per share and significant item charges related to the acquisition estimated to be $.23 to $.34 per share. In addition to these Danisco charges, the company expects a $.03 per share significant item charge in the third quarter associated with a licensing agreement.

 

ALTANA continues on its growth course

08-08-2011: The specialty chemicals Group ALTANA AG continued its growth course over the first six months of the current business year. Compared to the first half of 2010, the company was able to increase its sales by 9%, up from €773.1 million to €840.3 million. However, sharply rising raw materials costs which can only be passed on to customers with a certain time lag burden the company's profit. Earnings before interest, taxes, depreciation and amortization (EBITDA) grew less strongly by 1% to €172.9 million, compared to €171.5 million in the prior-year period. The EBITDA margin thus declined from 22.2% to 20.6%. Earnings before taxes (EBT) rose by 1% from €126.2 million to €127.0 million.

Sales in the BYK Additives & Instruments division rose strongly in the first six months of 2011; they were up from €279.5 million in the prior-year period to €314.4 million, which is an increase of 13%. The ECKART Effect Pigments division recorded sales of €184.6 million, an increase of 2% on the prior year (€180.2 million). Sales in the ELANTAS Electrical Insulation division improved by 10% and were up from €185.5 million to €203.3 million. The ACTEGA Coatings & Sealants division was also able to improve sales noticeably, achieving an increase of 8%. The division generated sales of €138.0 million following €127.9 million in the first half of 2010.

"We are looking back on a successful first half-year 2011, in which we were able to continue our dynamic growth of the past business year,“ stated Dr. Matthias L. Wolfgruber, CEO of ALTANA AG. "However, the partially massive raw materials cost increases negatively affect our earnings,“ continued Wolfgruber. "The best strategy against rising raw materials costs is a clear and strong focus on specialties with high relevance of research and service, which offer our customers added value,“ said Wolfgruber. "We will therefore maintain our course which is oriented to innovation and customer service in order to continue profitable growth in the future."

ALTANA anticipates sales growth in comparison with the prior year also for the second half of the current business year. However, compared to the first six months of 2011 the growth momentum is expected to slow down. The EBITDA margin 2011 should remain below the prior-year figure (20.5%) owing to the raw materials cost increases. Should the economic environment worsen, caused for example by the high public debt levels of many industrial nations, the business of ALTANA would also be affected.

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