Similar recipes for diets and 'ivory'.

Several years ago, polymer chemist Orlando A. Battista develped processes for extracting virus-sized crystals from cellulose and from synthetic polymers such as nylon and polyester (SN: 4/10/82, p. 246). Now, retired from industry and the president of his own Ft. Worth-based research institute, Battista is patenting diverse applications for insoluble gels made from these microcrystals and licensing the technologies to commercial developers. While a French company is preparing to market disposable contact lenses based on these gels, two of the newest licensed applications being pursuid in the United States are a diet aid and synthetic ivory.

Ordinary fibrous cellulose contains a chain of small crystals linked by hingelike fragments. Battista developed an acid process that cleaves off the hinges without attacking the crystals. Mixed with water, the crystals gel into an insoluble, creamlike glue, which is used widely as the pharmacologically inert binder holding many dry pills or tablets together.

For the diet aid, a microcrystalline-cellulose gel is used to bind ordinary cellulose fibers to a protein gelatin, like the gelatin that serves as the basis for Jell-O. "Cross-linking" the gelatin's protein -- adding a molecule that makes a covalent chemical bond between two amino acid chains -- gives it sustained resistance to acid degradation in the stomach. The result is that the protein takes longer to digest.

In processing, the gelatin-cellulose material is compressed to about 5 percent of its original volume. When later consumed with a glass of water, it will swell to about 20 times its consumed volume, exerting a mechanical pressure on the walls of the stomach so that the person truly feels full.

In the hour it takes the diet aid's proteing to break down in the stomach, the body will be fooled into thinking its caloric cravings have been sated, Battista says. Yet a 3-gram diet bar need not contain more than 2 or 3 calories. A small pill of the material, taken shortly before the meals, would allow diners to feel satisfied with smaller portions. In addition, Battista notes, these weight-control aids supply fiber to the diet.

"A cellulose-based pill is not a new idea" for dieting, says Christopher Smith in the Food and Drug Administration's (FDA's) Rockville, Md., office. FDA believes "the idea has merit," he told SCIENCE NEWS. The real question is whether it's safe and effective in helping people curb their appetites. And there will be no way of judging that, he says, until formal research studies on the product are submitted to FDA for review.

Preliminary clinical work has already been done, Battista told reporters at the recent American Chemical Society meeting in Chicago, although further clinical trials must still be conducted by the commercial developer before the product can win Food and Drug Administration approval. However, because the product contains only ingredients that FDA has already listed as "generally recognized as safe," Battista anticipates approval will not be difficult.

A similar recipe is used to concoct synthetic ivory. A different cross-linked gelatin (whose formulation is proprietary) is mixed with microcrystalline cellulose and calcium phosphate. Allowed to dry at room temperature for 10 weeks, the resulting material "has essentially the same chemical composition as elephant tusk," Battista says, and is virtually indistinguishable from real ivory.

Eliminating the calcium phosphate from the recipe and heating the material to 850[deg.]C in a nitrogen environment creates a one-third-sized carbon version of the original that preserves all structural details of the prefiring piece -- including any lathe marks or molecular pore configurations. Heating to 2,000[deg.]C converts the prefiring piece to graphite. Not only are these carbon and graphite materials more durable than those produced by the simple compression of petroleum pitch, Battista says, but they also make it easier to engineer larger and smaller structures.