NEWS OF THE WEEK gus, a previously unknown genus and position, the settlement was not entirely species, was named Taxomyces andrea-unanticipated. In mid-March, IMCF indicated that pretrial rulings might have adnae to honor Andrea Stierle. Why a fungus produces the same versely affected its defense. Wendell F. Bueche, IMCF's president compound as its host plant is still uncertain. But if genetic exchange between and chief executive officer, calls the host and fungus is involved, says Stro- agreement "costly," yet "manageable." bel, "it would be extremely important to IMCF's payment is in addition to about find out the mechanism—to understand $33 million it will spend to settle all perit and then be able to utilize it." He be- sonal injury claims in Texas litigation. lieves it possible "that any number of But personal injury lawsuits still continother important pharmaceuticals, besides ue in Louisiana. To cover the settlement Taxol, could also be found in fungi from and related expenses, IMCF will take a $109 million after-tax charge against pharmacologically important plants." Several firms have shown interest in earnings for the first quarter of 1993. All of IMCF's insurers initially denied licensing the Taxol-producing fungus technology, for which the university is coverage and refused to pay settlements seeking patent protection. "Main pros- unconditionally. In March, however, pectsrightnow are Bristol-Myers Squibb, IMCF reached an undisclosed settlement Lederle, and ESCAgenetics," says Strobel. with one insurer. IMCF now seeks recovStu Borman ery from its two other insurers. A spokesman says arbitration with one insurer is close to settlement, and IMCF has filed a lawsuit against the other. About a year ago, IMCF sold its ammonia production facilities in Sterlington to Koch Industries. With IMCF's deparIMC Fertilizer (IMCF) and Angus Chem- ture from the site, Angus assumed manical have settled a lawsuit stemming agement and operation of its nitroparaffrom a May 1991 explosion and fire at fins plant. Angus acquired the 38-yearAngus' Sterlington, La., nitroparaffins old plant in 1982 from International plant that killed eight workers and in- Minerals & Chemicals, since separated jured more than 100. The settlement will into Imcera and IMCF. Although the explosion knocked out Angus' basic nitrocost IMCF $180 million. The Occupational Safety & Health paraffins production, the rebuilt plant Administration found that the explo- returned to operation about a year ago. Ann Thayer sion was caused by unprotected piping and a lack of safety equipment. Despite OSHA's citation, IMCF denied any violation of laws or safety standards. The plant is owned by Angus, an Illinoisbased subsidiary of Alberta Natural Gas, and was operated under contract by IMCF, Northbrook, 111., which had Two independent research groups have its own operations at the site. shown that the tips of carbon tubules with Angus and its insurer filed suit dimensions on the scale of nanometers— against IMCF, seeking at least $280 mil- so-called carbon nanotubes—can be lion to cover property loss, interrupted opened by exposure to an oxidizing agent business, and punitive damages. Under and relatively mild heating. This research the agreement, IMCF will pay Angus opens the way to further characterization and Angus' insurer, Industrial Risk In- of these cousins of the fullerenes. surers, $180 million over a three-year Carbon nanotubes consist of concenperiod. Angus' share will be about $44 tric graphitic carbon tubes capped by million. IMCF also agrees to no longer fullerenelike hemispheres that curve seek reimbursement from Angus of the through incorporation of five-membered $9.8 million IMCF had to pay as part of rings. Scientists speculate open tubes a record $10 million fine by OSHA. might act as "nanoscale test tubes" for The settlement ends all pending litiga- studying catalysis and one- or lowtion between the two companies in Texas dimensional chemistry and physics. and Illinois courts, IMCF says. Although At Oxford University, England, MalIMCF rejected Angus' lawsuit claims and colm L. H. Green and coworkers heated said it would defend its limited liability nanotubes in carbon dioxide gas to 850
IMC Fertilizer settles lawsuit over explosion
Carbon nanotubes opened by oxidation
8
APRIL 12,1993 C&EN
°C. Corrosion in the cap region occurred in 5 to 10% of the nanotubes subjected to this treatment [Nature, 362, 520 (1993)]. Meanwhile, at NEC Corp. in Tsukuba, Japan, P. M. Ajayan, Thomas W. Ebbessen, Sumio Iijima, and coworkers showed that nanotube caps are attacked when the tubes are heated in air to about 700 °C [Nature, 362, 522 (1993)]. Both groups found that, in addition to opening the nanotubes, the oxidation reactions eat away the tubes' outer layers, effectively thinning their walls. Carbon nanotubes were discovered by Iijima in 1991. A method for bulk synthesis—graphite vaporization similar to that used to produce fullerenes—was developed by Ajayan and Ebbessen in 1992. Earlier this year, Iijima and Ajayan reported nanotubes open and fill with molten lead when they are heated to 400 °C in air in the presence of lead particles (C&EN, Feb. 8, page 31). At Oxford, Green, S. C. Tsang, and P. J. F. Harris used transmission electron microscopy (TEM) to study nanotubes exposed to heat and carbon dioxide. The images show, among other features, a nanotube from which the graphitic layers have been stripped near the tip, leaving a short, protruding inner tube of a type not seen before, as well as nanotubes in which the caps have been completely destroyed. They also report producing nanotubes from which all outer layers have been stripped, leaving tubes consisting of a single graphitic layer. NEC's Ajayan, Ebbessen, and Iijima and coworkers T. Ichihashi, K. Tanigaki, and H. Hiura find that nanotubes that are first opened by heating in the presence of oxygen, and then exposed to molten lead, fill less easily than tubes that are opened in the presence of molten lead. They speculate that the inside cavities of closed tubes are vacuums or near-vacuums, and that when the tubes are opened in the presence of a liquid, the liquid is sucked in. They note that the "meaning of vacuum in such small cavities is unclear." The presence of pentagons in the curved regions of the nanotube tips almost certainly plays a role in the susceptibility of the tips to oxidation, say both groups. The NEC researchers report that experiments with polyhedral carbon nanoparticles—which contain the same number of pentagons as nanotubes but a lesser degree of curvature—suggest strain "must be the key factor in the onset of oxidation at the nanotube tips." Rudy Baum
