Pre-emptive analgesia from intravenous administration of opioid: no effect with pentazocine

The influence of timing of administration of preoperative pentazocine on pain and analgesic requirements after surgery was studied in 46 patients undergoing total abdominal hysterectomy. Twenty-three patients received thiamylal 5 mg.kg-1 on induction of anesthesia, followed by pentazocine 30 mg or 60 mg before surgical incision (group A). Twenty-three control patients received pentazocine 30 mg or 60 mg, 5 min after abdominal incision (group B). The visual analogue scales for pain 24 h after operation were 6.0 cm at 30 mg dose in group A or 5.3 cm at 60 mg dose in group A and 5.7 cm at 30 mg dose in group B or 4.7 cm at 60 mg dose in group B. There were no differences in the visual analogues scales. Pentazocine consumption in the first 24 h after surgery was 67.5 mg at 30 mg dose in group A or 52.5 mg at 60 mg dose in group A and 70.9 mg at 30 mg dose in group B or 51.8 mg at 60 mg dose in group B. We conclude that postoperative pentazocine consumption and pain scores are no different when pentazocine is given before or after skin incision for abdominal hysterectomy and that there is no clinically useful pre-emptive analgesic effect with these doses of pentazocine.     

Suppression of Active Oxidation of Polycarbosilane-Derived Silicon Carbide Fibers by Preoxidation at High Oxygen Pressure

Three types of polycarbosilane-derived SiC fibers (Nicalon, Hi-Nicalon, and Hi-Nicalon S) with different SiO₂ film thicknesses ( b ) were subjected to exposure tests at 1773 K in an argon-oxygen gas mixture with an oxygen partial pressure of 1 Pa. The suppression effect of a SiO₂ coating on active oxidation was examined through TG, XRD analysis, SEM observation, and tensile tests. All the as-received fibers were oxidized in the active-oxidation regime. The mass gain and the SiO₂ film development showed a suppression of active oxidation at b values of ≧0.070 μm for Nicalon, ≧0.013 μm for Hi-Nicalon, and ≧0.010 μm for Hi-Nicalon S fibers. Considerable strength was retained in the SiO₂-coated fibers. For Hi-Nicalon fibers, the retained strength was 71%–90% of the strength in the as-received state (2.14–2.69 GPa).     

Vinyl polymerization by metal complexes. XVI. Photopolymerization of vinyl monomers by metal-amine systems

The photopolymerization of vinyl monomers was studied by the system of metal-amine complex and carbon tetrachloride. Addition of amines to the initiating system generally accelerates the polymerization. The acceleration by various sorts of amines in different solvents was examined. It was confirmed that the photopolymerization in question is of free radical character. The polymerization mechanism was discussed.     

Diffusion of vanadium,chromium, and manganese in copper

The diffusion coefficients of vanadium, chromium and manaanese in copper have been determined by the residual activity method with radioactive tracers V⁴⁸, Cr⁵¹ and Mn⁵⁴ in the temperature ranges between 955 and 1342 K, between 999 and 1338 K and between 971 and 1253 K, respectively. The temperature dependence of the diffusion coefficients is expressed by the following Arrhenius equations along with the probable errors:D _V/Cu = (2.48 _-0.44 ^+0.53 ) x 10⁻⁴ exp [-(215 ± 2) kJ mol⁻¹/RT] m² per s,D _Cr/Cu = (0.337 _-0.090 ^+0.124 ) x 10⁻⁴ exp [-(195 ± 3) kJ mol⁻¹/RT] m² per s,D _Mn/Cu = (1.02 _-0.18 ^+0.22 ) x 10⁻⁴ exp [-(200 ± 2) kJ mol⁻¹/RT] m² per s. Anomalous penetration profiles for the diffusion of Cr⁵¹ and Mn⁵⁴ in the present results suggest that experimental results onD _Cr/Cu andD _Mn/Cu in the past have been influenced by oxidation and evaporation of the chemically active radiotracers during annealing for diffusion. formerly Graduate Student, Tohoku University     

High-speed planar-structure Inp/InGaAsP/InGaAs avalanche photodiode grown by VPE

Planar-structure InP/InGaAsP/InGaAs avalanche photo-diodes have been realised by using a VPE-growth technique and a Be+ implanted guard ring. Sensitivity measurement has been performed at 1.3 ?m and 1.8 Gbit/s. The minimum average received level required for 10?9 BER was ?31.3 dBm, which was 1.2 dB better than the value for the Ge-APD.