Dissociative electron attachment to the highly reactive difluoromethylene molecule–importance of CF2 for negative ion formation in fluorocarbon plasmas

Dissociative electron attachment to the highly reactive difluoromethylene molecule, CF2, produced in a C3F6/He microwave plasma and stepwise via the fast atom reaction CF3I+H?CF3+HI and CF3+H?CF2+HF, has been investigated. The upper limit for the cross section of formation of F- via dissociative electron attachment to CF2 is estimated to be 5×10-4?Å2. This value is four orders of magnitude smaller than the cross section previously predicted from scattering calculations. It is concluded that difluoromethylene plays a negligible role in negative ion formation in fluorocarbon plasmas.

INCIDENCE AND CLINICAL IMPORTANCE OF PERIOPERATIVE HISTAMINE-RELEASE - RANDOMIZED STUDY OF VOLUME LOADING AND ANTIHISTAMINES AFTER INDUCTION OF ANESTHESIA

Although histamine release is recognised as a common event during anaesthesia and surgery, few clinicians judge the resultant cardiorespiratory disturbances serious enough to warrant prophylaxis with antihistamines. We have assessed the incidence and importance of histamine release in a randomised 2 x 2 factorial study.

Chemical control through dissociative electron attachment - A study on pentafluorotoluene, pentafluoroaniline and pentafluorophenol

In a combined experimental and theoretical study on dissociative electron attachment (DEA) to pentafluorotoluene, pentafluoroaniline and pentafluorophenol in the energy range 0-3 eV we reveal the role of rearrangement and hydrogen bonded intermediates in the DEA process and show that HF formation can be used to enable otherwise inaccessible, efficient low energy DEA processes.

Dissociative electron attachment to C2F5 radicals

Dissociative electron attachment to the reactive C2F5 molecular radical has been investigated with two complimentary experimental methods; a single collision beam experiment and a new flowing afterglow Langmuir probe technique. The beam results show that F- is formed close to zero electron energy in dissociative electron attachment to C2F5. The afterglow measurements also show that F- is formed in collisions between electrons and C2F5 molecules with rate constants of 3.7 × 10-9 cm3 s-1 to 4.7 × 10-9 cm3 s-1 at temperatures of 300–600 K. The rate constant increases slowly with increasing temperature, but the rise observed is smaller than the experimental uncertainty of 35%.

Ocular anesthesia in the new millennium

In the new millennium anesthetic agents will be safer and more efficient. Topical anesthesia will be the most frequently used technique. Time- and cost-saving measures will expand the current trend of outpatient surgery and anesthesia will be reduced. Patients' perioperative comfort will improve.

Subconjunctival versus peribulbar anesthesia in trabeculectomy:A prospective, randomized study

BACKGROUND AND OBJECTIVE: To compare the use of subconjunctival and peribulbar anesthesia for trabeculectomy. PATIENTS AND METHODS: Sixty patients undergoing trabeculectomy were prospectively randomized to receive either peribulbar or subconjunctival anesthesia. Peribulbar anesthesia consisted of a 3-ml inferior and a 1-ml superior injection of a 1:1 mixture of 2% mepivacaine, 0.75% bupivacaine, and hyaluronidase. Subconjunctival anesthesia consisted of a 1- to 2-ml injection of the same mixture without hyaluronidase in the superotemporal quadrant. Intraoperative pain, presence of eye movements, and complications during surgery were evaluated. RESULTS: The frequency and intensity of pain was statistically similar between the two groups. All episodes of pain (20% in the subconjunctival group and 6.6% in the peribulbar group) were rated as mild. Eye movement was more common in the subconjunctival group than in the peribulbar group, but it was controlled by verbal command and did not interfere with the procedure. No clinically significant complications occurred during surgery. CONCLUSION: Subconjunctival anesthesia is an effective alternative to peribulbar anesthesia for trabeculectomy.

Preliminary clinical assessment of polyvinyl alcohol-tetrahydroxyborate hydrogels as potential topical formulations for local anesthesia of lacerations

The aim of this study was to assess a novel semisolid material as a potential topical drug delivery system for acute laceration. The objectives were to correlate physical characterization data using rheologic studies and to compare with clinical assessment of performance in an emergency department (ED).