"Pompeian red is really special. It represents the height of the ancient Romans’ mastery in making colors," said Daniela Daniele, a researcher at Berlin's State Museum. That unique quality makes it all the more important to learn how to preserve Pompeii’s brilliant red pigment.
They used an unusually fine grind (2~3 µm), which makes the pigment’s color more intense. They also mixed in larger crystals 10~15 µm, which gave a shiny quality to the surface. Cinnabar that is processed in the typical way yields a dull red similar to red ochre.
Artificial Atoms
Jim_Kling
Image Courtesy: PlasmaChem GmbH, Berlin, GermanySpherical particles of a few thousand atoms " known as nanoparticles " have been used as artificial atoms to create larger crystals that could find use in a variety of applications, such as nanoparticle-based transistors or wave guides for use in biosensors, or as computer components.
Nanoparticles are often coated with rod-like molecules to prevent further growth or agglomeration. This 'ligand shell' can be made to react with other molecules and link up with other nanoparticles to form polymers, but it does so with no particular preference the resulting structures tend to be amorphous. Nanoparticles would be even more useful if researchers could get them to assemble in a directed manner.
Francesco Stellacci and his colleagues at the Massachusetts Institute of Technology team synthesized gold nanoparticles and used a combination of 1-nonanethiol and 4-methylbenzenethiol as the ligand surface. They then used a two phase polymerization reaction inspired by the procedure to synthesize nylon. The nanoparticles were first exposed to a solution of 11-mercaptoundecanoic acid to form disulfide bonds with the 1-nonanethiol, leaving the carboxylic acid group from 1-nonanethiol protruding into space. They predicted that the polar 1-nonanethiol residues would be the first to react with the 11-mercaptoundecanoic acid, so that when the reaction was quenched it would yield nanoparticles with two modified poles. They then treated the mixture with a 1,6-diaminohexane and an activating agent to form amide bonds that would link the resulting carboxylic acid residue to the carboxylic acid residue hanging off of another nanoparticle.
Transmission electron microscopy images of the resulting precipitate revealed linear nanoparticle chains and no sign of aggregates. The particles formed films as large as 1 cm2 and up to 60 microns thick. Such films have the potential to be used as nano-waveguides for use in biosensors. Linked nanoparticles transfer light in a characteristic way, and this can be altered when they are bound to a biological molecule. This change can be used to sense the molecule's presence.
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Technology
Intel Unveils New Transistor
Hafnium-based materials will be incorporated in 45-nm-technology chips
Alex Tullo
In what it dubs the "biggest change to computer chips in 40 years," Intel says it is using hafnium-based dielectric insulating materials with metal gates to construct the transistors in its new 45-nm-technology chips.
During those 40 years, silicon dioxide, the transistor dielectric material of choice, was made thinner and thinner to maintain adequate capacitance as chip size shrank. In the most advanced chips in production today, which have 65-nm circuit lines, the SiO2 layer is only 1.2 nm thick.
But making SiO2 thinner has also led to electrical leakage and excess heat. For the 45-nm transistor, Intel is replacing SiO2 with a hafnium-based material. With their higher dielectric constants, or k values, hafnium compounds form a thicker gate that blocks electrons while maintaining capacitance.
And because the new high-k dielectric material is not compatible with conventional silicon gate electrodes, Intel is using an unnamed metal as the gate electrode.
Intel says the new materials reduce transistor current leakage by more than 90% compared with SiO2. Successfully implementing 45-nm process technology permits a doubling of the transistor density on the chip.
"The implementation of high-k and metal materials marks the biggest change in transistor technology since the introduction of polysilicon gate MOS [metal-oxide-semiconductor] transistors in the late 1960s," Intel cofounder Gordon Moore said in a statement.
Intel isn't alone in using high-k materials to push chip size smaller. A day after Intel's announcement, IBM said it had successfully made transistors with an unspecified high-k and metal combination with partners Advanced Micro Devices, Sony, and Toshiba. IBM plans to incorporate its version of the new technology into chips next year.
But Intel intends to be the first on the market with commercial 45-nm-technology chips. The company is developing 15 45-nm processor products, five of which are being tested. The company intends to ramp up production of 45-nm-technology chips at facilities in Oregon and Arizona at the end of the year and in Israel by the first half of 2008.
Chemical & Engineering News
ISSN 0009-2347
Bush Proposes 20% Cut In U.S. Gas Use
President wants more non-oil-based fuel, better vehicle efficiency
Jeff Johnson
http://pubs.acs.org/cen/staff/biojwj.html
His intention this time is to cut projected gasoline use by 20% by 2017. The plan would reduce U.S. gasoline consumption by 8.5 billion gal through better vehicle efficiency and cut another 35 billion gal of gas by substituting renewable or alternative fuels.
Bush's new alternative fuel target is nearly five times the government's current goal of producing 7.5 billion gal of renewable fuel by 2012. Nearly all of today's renewable fuel comes from corn-based ethanol, and the field is booming. Refiners expect to reach the 2012 target this year or next.
However, Bush's plan would eat up the nation's entire corn crop. Hence, the new goal will be a driver for cellulosic feedstocks—grasses, trees, corn stalks—as well as more energy crop acreage and more intense farming methods (C&EN, Dec. 4, 2006, page 57).
The Administration allows fuel options besides ethanol, but with the exception of biodiesel, none are produced today in sufficient quantities to influence the President's goal.
The Administration's vehicle efficiency goals are premised on a 4% annual efficiency increase beginning in 2010. Details are few, and Bush wants specifics to be left to the secretary of transportation. The Union of Concerned Scientists estimates Bush's proposal would raise average efficiency to 34 miles per gal from today's top rating of 27 mpg.
The day after Bush's address, the Administration issued an executive order requiring federal agencies to improve energy efficiency and cut annual energy use by 3% through 2015. And the President visited DuPont's biofuels experiment station in Wilmington, Del., where he toured the company's biobutanol and cellulosic research projects.
http://www2.dupont.com/
Chemical & Engineering News
ISSN 0009-2347
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