Hybrid Nanocrystals of Small Molecules and Chemically Disordered Polymers

Organic crystals formed by small molecules can be highly functional but are often brittle or insoluble structures with limited possibilities for use or processing from a liquid phase. A possible solution is the nanoscale integration of polymers into organic crystals without sacrificing long-range order and therefore function. This enables the organic crystals to benefit from the advantageous mechanical and chemical properties of the polymeric component. We report here on a strategy in which small molecules cocrystallize with side chains of chemically disordered polymers to create hybrid nanostructures containing a highly ordered lattice. Synchrotron X-ray scattering, absorption spectroscopy, and coarse-grained molecular dynamics simulations reveal that the polymer backbones form an "exo-crystalline" layer of disordered chains that wrap around the nanostructures, becoming a handle for interesting properties. The morphology of this "hybrid bonding polymer" nanostructure is dictated by the competition between the polymers' entropy and the enthalpy of the lattice allowing for control over the aspect ratio of the nanocrystal by changing the degree of polymer integration. We observed that nanostructures with an exo-crystalline layer of polymer exhibit enhanced fracture strength, self-healing capacity, and dispersion in water, which benefits their use as light-harvesting assemblies in photocatalysis. Guided by computation, future work could further explore these hybrid nanostructures as components for functional materials.

High-quality graphene via microwave reduction of solution-exfoliated graphene oxide

Efficient exfoliation of graphite in solutions to obtain high-quality graphene flakes is desirable for printable electronics, catalysis, energy storage, and composites. Graphite oxide with large lateral dimensions has an exfoliation yield of ~100%, but it has not been possible to completely remove the oxygen functional groups so that the reduced form of graphene oxide (GO; reduced form: rGO) remains a highly disordered material. Here we report a simple, rapid method to reduce GO into pristine graphene using 1- to 2-second pulses of microwaves. The desirable structural properties are translated into mobility values of >1000 square centimeters per volt per second in field-effect transistors with microwave-reduced GO (MW-rGO) as the channel material and into particularly high activity for MW-rGO catalyst support toward oxygen evolution reactions.

Effects of intraoperative glucose on protein catabolism and plasma glucose levels in patients with supratentorial tumors

Animal studies suggest that hyperglycemia (glucose concentrations greater than 225 mg/dl) occurring prior to periods of brain ischemia exacerbates neurologic damage. Neurosurgical patients, a group at risk for intraoperative brain ischemia, often receive glucose. Therefore, the effects of intraoperative glucose administration (IGA) on these patients were studied. Sixteen patients undergoing supratentorial craniotomy were randomly assigned to receive either 5% glucose in 0.9% sodium chloride solution (G) or 0.9% sodium chloride solution (S) infusion (both at a rate of 3-4 ml X kg-1 X h-1) during the first 4 h of surgery. All patients received glucose infusions postoperatively. Plasma glucose, insulin, free fatty acids, alanine, ketones, base excess, pH, triglycerides, and lactate were measured during the infusion period and 24 h postoperatively. Urinary nitrogen was measured, commencing with the infusion and continuing for 24 h. Neurologic testing included preoperative and postoperative neurologic and psychomotor exams, time to extubation (min), and degree of alertness at the completion of anesthesia. The G group had significantly greater intraoperative plasma glucose concentrations at all time periods studied during the infusion (P less than 0.05). Glucose levels ranged from 200-242 mg/dl compared with 120-160 mg/dl in G and S groups, respectively. G group hyperglycemia was within the range associated with exacerbation of ischemic brain damage in animal studies. Free fatty acids and ketones were significantly greater (P less than 0.05) intraoperatively in the S group. Lactate and insulin were significantly greater in the G group at 4 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Diphenylhydantoin, phenobarbital, and primidone in saliva, plasma, and cerebrospinal fluid

Diphenylhydantoin, primidone, and phenobarbital were determined in saliva and plasma of 164 patients by gas-liquid chromatography. The saliva ratio was about one-tenth in patients on diphenylhydantoin, 0.32-0.38 on phenobarbital alone and with other drugs, 0.97 and 0.96 on primidone alone and with other drugs. The S/P ratio of phenobarbital was similar in patients treated with primidone alone or with co-medication. For diphenylhydantoin and primidone, the S/P and CSF/plasma ratio were similar; for phenobarbital the S/P ratio was lower due to the difference in pH of saliva and CSF. Thus the concentration in saliva serves as a measure of the nonprotein-bound or free concentration in plasma with the advantage that saliva is easy to obtain. Co-medication does not change the S/P ratio for the three drugs studied. The high correlation between levels in plasma and in saliva allows the plasma levels to be predicted from the concentration in saliva.