Water on Au sputtered films.

Transient changes in the contact angle, Δθ ∼ 10°, of water on gold (Au) reveal reversible wetting of near hydrophobic Au films. The recovery time is temperature dependent. Surface flatness is investigated using AFM and profilometery.

Anaesthesia for spinal surgery in adults.

The spectrum of spinal surgery in adult life is considerable. Anaesthesia for major spinal surgery, such as spinal stabilization following trauma or neoplastic disease, or for correction of scoliosis, presents a number of challenges. The type of patients who would have been declined surgery 20 yr ago for medical reasons, are now being offered extensive procedures. They commonly have preoperative co-morbid conditions such as serious cardiovascular and respiratory impairment. Airway management may be difficult. Surgery imposes further stresses of significant blood loss, prolonged anaesthesia, and problematical postoperative pain management. The perioperative management of these patients is discussed. The advent of techniques to monitor spinal cord function has reduced postoperative neurological morbidity in these patients. The anaesthetist has an important role in facilitating these methods of monitoring.

Abiotic hydrolysis of the detergent builder tripolyphosphate by hydrous manganese dioxide.

The hydrolysis of tripolyphosphate to orthophosphate is facilitated by suspensions of amorphous manganese dioxide. Pyrophosphate is observed as an intermediate. The rate enhancement decreases with increasing pH. The weak sorption of orthophosphate on the oxide also decreases with increasing pH, indicating that the orthophosphate product would be bioavailable. The presence of calcium ions in natural waters increases both the rate of hydrolysis of tripolyphosphate and the extent of sorption of orthophosphate. Under some circumstances this abiotic mechanism could play a significant role in the hydrolysis of tripolyphosphate in the aquatic environment.

Hydrolysis of an organophosphate ester by manganese dioxide.

Amorphous manganese dioxide facilitates the hydrolysis of p-nitrophenyl phosphate to p-nitrophenol and orthophosphate despite insignificant adsorption of p-nitrophenyl phosphate or p-nitrophenol to the manganese dioxide. At pH 8, the orthophosphate product is released into solution; at pH 4 and pH 6, some remains adsorbed. The rate of hydrolysis is an order of magnitude more rapid than the same reaction facilitated by iron oxides. Because manganese dioxides are ubiquitous components of soils and sediments, this suggests the possibility of significant abiotic pathways for the formation of bioavailable orthophosphate from phosphate ester precursors.

Spin state and unfolding equilibria of ferricytochrome c in acidic solutions.

Equilibrium, stopped flow, and temperature-jump spectrophotometry have been used to identify processes in the unfolding of ferricytochrome c in acidic aqueous solutions. A relaxation occurring in approximately 100 microseconds involves perturbation of a spin-equilibrium between two folded conformers of the protein with methionine-80 coordinated or dissociated from the heme iron. The protein unfolds more slowly, in milliseconds, with dissociation and protonation of histidine-18. These two transitions appear cooperative in equilibrium measurements at low (0.01 M) ionic strength, but are separated at higher (0.10 M) ionic strength. They are resolved under both conditions in the dynamic measurements. The spin-equilibrium description permits a unified explanation of a number of properties of ferricytochrome c in acidic aqueous solutions.

An NMR investigation of electron transfer in the copper-protein, plastocyanin.

1. The proton NMR spectra of oxidised and reduced French bean plastocyanin have been recorded on a 270 MHz pulsed spctrometer. 2. The spectrum of a mixture containing the protein in the paramagnetic Cu(II) and diamagnetic Cu(I) states is a superposition of the separate spectra. When ferrirate spectra. 3. The results show that self-exchange between Cu(II)- and Cu(I)-plastocyanin is slow on the NMR time scale (kex less than 2-10(4) M-1-s-1 at 50 degrees C), and that electron transfer in the presence of ferricyanide is rapid (k greater than 1-10(5) M-1-s-1).