sponsored by the Institute of Medi­cine in Washington, D.C., the panel particularly cited blood levels of CD4 lymphocyte cells as the best surrogate marker to augment or re­place other indicators in efficacy trials of new AIDS drugs.

Patient survival rates and frequen­cy of opportunistic infections are "clinical endpoints" that the Food & Drug Administration currently ac­cepts as evidence of drug effective­ness. But these tests are slow, tend­ing to keep potentially beneficial drugs out of the hands of desperate patients for long periods while trials proceed. Surrogate endpoints could be evaluated more quickly, thus speeding drug approvals.

Of several surrogates under con­sideration, the CD4 marker is now furthest along for use in clinical AIDS trials, according to Anthony S. Fauci, director of the Office of AIDS Research at the National In-

The Administration and Congress are chipping away at the massive environmental, health, and safety problems besetting the Department of Energy's nuclear arms plants.

Acting on one of the highest pro­file problems, DOE Secretary James D. Watkins has approved a plan for restarting production of tritium at the Savannah River complex near Aiken, S.C. No DOE plant has been making tritium, a vital nuclear weap­on component, for more than a year, and Watkins gives high priority to resuming production.

However, members of Congress and environmental groups fear DOE may try to resume production be­fore it can complete an environ­mental impact statement (EIS) and finish ultrasonic testing for possi­ble reactor cracks. Three environ­mental groups have sued DOE to require an EIS before restart.

Congress last week vastly expand­ed funding for cleanup and envi­ronmental restoration at the nucle­ar arms plants, beefing up what DOE describes as a 30-year effort.

The restart plan, prepared by the Westinghouse Savannah River Co., which has operated the 192,000-acre site since Du Pont pulled out last

stitutes of Health. A number of AIDS studies on CD4, he says, "under­score what immunologists have known for some time—that you need CD4-positive lymphocytes or else you will not do well There has been an unequivocal associa­tion between low levels of CD4 cells and measurable deleterious events."

Panelist Jay C. Lipner, partner in a New York law firm that repre­sents AIDS advocacy groups and himself an AIDS patient, added a note of urgency to the proceedings. "I'm not going to sit up here and argue against good science," he says. "However, there is a certain amount of uncertainty that's inevitable in this. . . . I think that the research community is going to have to ac­cept a certain amount of uncertain­ty and realize that they're not going to have perfect markers We can­not wait; this must proceed."

Stu Borman

April, calls for the plant's K reactor to begin low-power testing "late in the third quarter" of 1990, and to resume tritium production "in the fourth quarter." The L and P reac­tors would follow at three-month intervals. Watkins says he will make a final decision on whether to go ahead and on precise startup dates only after a detailed program re­view about next April.

Assailed by charges of misman­agement and safety and environ­mental problems, DOE shut down the K, L, and P reactors last year for "maintenance and improvements." DOE had originally hoped to re­sume production last December but it now appears tritium production will be halted at least two years.

The N reactor at DOE's Hanford complex near Richland, Wash., could also make tritium. However, it is not currently operating and Watkins is expected to send it into moth­balls soon, anyway. Thus, until new reactors can be built, U.S. strategic weapons will continue to depend for tritium upon the three 35-year-old Savannah reactors, all of which be­gan operating in 1954.

Meanwhile, the House and Sen­ate last week gave final passage to

the energy and water development appropriation for fiscal 1990, con­taining $1.66 billion for cleaning up the nuclear arms complex—more than two thirds above spending in the current fiscal year. Moreover, the bill gives the DOE weapons com­plex a total of $2.4 billion when all related environmental restoration and waste management activities are included, a figure that is projected to reach $4 billion by fiscal 1993.

Richard Seltzer

Dow, Sikorsky join in composites venture Dow Chemical and the Sikorsky Air­craft division of United Technolo­gies Corp. are forming a joint ven­ture to produce, design, manufac­ture, and market advanced composite products. Financial terms of the joint venture haven't been released.

Advanced composites, consisting of graphi te- , glass-, or aramid-reinforced thermoplastic and ther-moset resins, are increasingly being used in high-stress, high-perform­ance materials. Components devel­oped through the Dow-Sikorsky Air­craft venture are to be supplied to the aerospace, defense, automotive, and industrial markets.

The use of lightweight, high-strength advanced composites in these markets is expected to increase at an annual rate of at least 9% over the next several years, according to SRI International. Worldwide sales of advanced composite components reached $1 billion in 1988 and are expected to hit $2 billion by 1993. The projected growth, the two com­panies believe, "merits the focus of a new company/ '

The company will be competing with others, such as FMC and Al­l ied-Signal , w h o , in addi t ion to being among the many producers of advanced composite materials, also have their own defense, aero­space, or automotive divisions. The joint venture is expected to begin operation in early 1990. Annual sales are projected to be $75 million in the first year, and are estimated to reach $600 mil l ion by the late 1990s.

Dow will supply capital, R&D ef-

Tritium production to resume in late 1990

September 18, 1989 C&EN 7

News of the Week

New technology yields polycarbonates

Bisphenol A Bis(chloroformate)

forts, commercial resources, and li­censing rights to its advanced com­posites fabrication technologies. United Technologies will contrib­ute its existing Sikorsky Aircraft pro­duction facility in Tallassee, Ala., along with research, engineering, and design groups located in Con­necticut. The new company will be based in Connecticut and will em­ploy about 500 people.

Ann Thayer

FROM MIAMI BEACH

New polymerizations broaden carbonate uses New developments in polymeriza­tion of carbonates at General Elec­tric promise to expand markets for these polymers in a range of prod­ucts including windows and sport­ing equipment. These processes open doors to new composites and crosslinked resins and to better ways of fabricating polycarbonates. Some of the details of the technolo­gies were unveiled last week at the American Chemical Society meet­ing in Miami Beach.

The technique , says John W. Verbicky, manager of GE Research & Development Center's chemical synthesis laboratory, is based on the first practical synthesis of very large cyclics. It is also applicable to polyarylates, aramids, and ether/ thioether-imide and -sulfone resins.

U.S. consumption of polycarbo­nates will be almost 500 million lb in 1989. Domestic producers are Dow (100 million lb per year capac­ity), GE (420 million lb), and Mobay (160 million lb). Notable among the current diverse appl icat ions of polycarbonates are windows (25%), transportation (15%), electrical and electronic devices (12%), and indus­trial (11%) and sporting equipment (10%).

One polycarbonate technology, Verbicky says, is based on reaction of bisphenol A and its bis(chloro-formate) ester to form cyclic oligo­mers ranging from 24 rings to 240. This material is a powder that, when heated, melts and flows easily into the tight spaces in a complex fiber-reinforcing network.

Cyclic oligomers n = 1-20

Anionic catalysts trigger opening of rings, whose "l iving" anionic ends attack other rings, leading to chain growth. Catalyst concentra­tions control molecular weights that range from 50,000 to 700,000. Molecular weights of conventional polycarbonates, made by reaction of bisphenol A and phosgene, are 40,000 to 60,000.

Crosslinked polycarbonates result

FROM MIAMI BEACH

Forest survey finds 75% less biomass The northern forests of North Amer­ica may contain only one fourth as much biomass as previously calcu­lated report Daniel B. Botkin and Lloyd G. Simpson of the University of California, Santa Barbara.

Each square meter of the ever­green forest, according to their sur­vey sample, contains an average of about 4 kg of above-ground bio­mass. The entire forest has a total of about 22 billion metric tons. Previ­ous estimates of the average bio­mass contained in one square meter range from 12 to 18 kg.

Large-scale measurements are es­sential for understanding global warming, because they are needed for determining the potential for forests to absorb the carbon dioxide produced by the burning of fossil fuels and for determining how much carbon is released by forest clear-

Catalyst / r ^ r r n \

Polycarbonate

g from inclusion of such compounds c as the internal cyclic bis(carbonate) o of l,5-tetrakis(3,5-dimethyl-2-hy-i- droxyphenyl)pentane or a copoly-:s mer of styrene and glycidyl meth-). acrylate in the oligomer mixture, d Ring-opening polymerization of cy->f clic oligomers made by reaction of e bisphenol A and isophthaloyl chlo­

ride yields polyarylate resins. It Stephen Stinson

ing. "It has become commonplace to suggest that vegetation might se­quester major amounts of carbon and that the additional large-scale plant­ing of trees might provide an addi­tional sink for carbon," Botkin told

r- attendees at last week's meeting of is the American Chemical Society, i- Since there was no agreement on d the boundaries of the boreal for-y ests, Botkin defined them with en­

vironmental features. He used July r- mean isotherms to set the north and r- south boundaries and subdivided the >f area into 12 regions whose bound->- aries were defined by climatic, geo->f logic, and soil patterns. Equal-sized i- units were sampled in each region. )- Botkin says his study is the first ?r attempt to gather statistically reli­

able estimates of vegetation biomass 5- for a large area of Earth. In other il studies, areas with mature trees were d sampled and the measurements ex->r trapolated to large regions. Botkin e notes there is a general lack of in-il formation on the interactions be­ll tween global climate and vegetation, r- Bette Hileman

8 September 18, 1989 C&EN