Removal and reinsertion of cemented femoral components during acetabular revision

The Mayo block is an extremely efficacious regional anesthetic technique used to provide anesthesia of the forefoot. Patients requiring surgical correction of hallux deformity, bunionectomy, and first metatarsal surgery may benefit from this technique. The Mayo block is a field block that anesthetizes the specific nerves of the forefoot that innervate the surgical field. This technique requires less local anesthesia than that required by direct local anesthetic infiltration and does not distort the surgical tissue planes. The Mayo block is effective. This technique has been used at one military hospital on more than 275 patients. The failure rate of the block is less than 1%. Learning this technique adds to the anesthetist's armamentarium of regional anesthesia, aids in rapid case turnover, and avoids the risks associated with major conduction and general anesthesia.     

A model of the quaternary structure of enolases, based on structural and evolutionary analysis of the octameric enolase from Bacillus subtilis

Purified enolase from Bacillus subtilis has a native mass of approximately 370 kDa. Since B. subtilis enolase was found to have a subunit mass of 46.58 kDa, the quaternary structure of B. subtilis is octameric. The pl for B. subtilis enolase is 6.1, the pH optimum (pHo) for activity is 8.1-8.2, and the Km for 2-PGA is approximately 0.67 mM. Using the dimeric Calpha structure of yeast dimeric enolase as a guide, these dimers were arranged as a tetramer of dimers to simulate the electron microscopy image processing obtained for the octameric enolase purified from Thermotoga maritima. This arrangement allowed identification of helix J of one dimer (residues 86-96) and the loop between helix L and strand 1 (HL-S1 loop) of another dimer as possible subunit interaction regions. Alignment of available enolase amino acid sequences revealed that in 16 there are two tandem glycines at the C-terminal end of helix L and the HL-S1 loop is truncated by 4-6 residues relative to the yeast polypeptide, two structural features absent in enolases known to be dimers. From these arrangements and alignments it is proposed that the GG tandem at the C-terminal end of helix L and truncation of the HL-S1 loop may play a critical role in octamer formation of enolases. Interestingly, the sequence features associated with dimeric quaternary structure are found in three phylogenetically disparate groups, suggesting that the ancestral enolase was an octamer and that the dimeric structure has arisen independently multiple times through evolutionary history.     

Heterojunction InAlAs/InP MESFETs grown by OMVPE

Lattice-matched InAlAs/n-InP and InAlAs/n⁺-InP heterostructure MESFETs with extrinsic transconductances of 220 and 155 mS/mm, respectively, have been fabricated on semi-insulating InP substrates. Maximum stable gains of 11.5 dB for the 1.25-μm-gate n-InP channel and 10 dB for the 1.0-μm-gate n⁺-InP channel devices were measured at 10 GHz. An extrapolated f_max of 42 GHz was obtained for the n⁺-channel MESFET     

Relationships between labile-P,NAHCO3-soluble P,and mobilisation of non-labile P in soils treated with inorganic phosphate fertilisers and organic manures

Weighted-mean L-values and uptakes of P by plants were determined using ryegrass grown in a controlled environment on soils obtained from long-term field experiments at Rothamsted (Batcombe and Winchester soil series), Woburn (Stackyard and Cottenham series) and Saxmundham (Beccles series) given different organic and inorganic manurial treatments. Linear regression analysis showed that, under the experimental conditions used, (small soil volume, weekly additions of all nutrients other than P) initial soil NaHCO₃-soluble P accounted for more than 95% of the variance of plant-P uptake and weighted-mean L-values. The relationships between NaHCO₃-soluble P, plant-P uptakes and weighted-mean L-values (labile P) were all independent of soil type and form of P fertiliser applied. In most soils, L-values increased with increasing cut number, and the rate of increase was linearly related to initial soil NaHCO₃-soluble P, suggesting that NaHCO₃-P measurements may provide useful information on the availability of initially non-isotopically exchangeable soil-P reserves. The plants removed about 68% more P from the soils than was measured as initially NaHCO₃-soluble and about one-half the labile soil-_P. Labile soil-P was 3.5 times greater than initial NaHCO₃-soluble P. The initial soil NaHCO₃-soluble P required to provide at least 95% of maximum yield increased with increasing cut number (from 37 mg P kg^?1 soil at cut 1 to 160 mg P kg^?1 soil at cut 4), probably because the NaHCO₃-P pool was replenished more slowly than P was removed by the plants.     

The Characterization of a Piston Displacement-Type Flowmeter Calibration Facility and the Calibration and Use of Pulsed Output Type Flowmeters

Critical measurement performance of fluid flowmeters requires proper and quantified verification data. These data should be generated using calibration and traceability techniques established for these verification purposes. In these calibration techniques, the calibration facility should be well-characterized and its components and performance properly traced to pertinent higher standards. The use of this calibrator to calibrate flowmeters should be appropriately established and the manner in which the calibrated flowmeter is used should be specified in accord with the conditions of the calibration.These three steps: 1) characterizing the calibration facility itself, 2) using the characterized facility to calibrate a flowmeter, and 3) using the calibrated flowmeter to make a measurement are described and the pertinent equations are given for an encoded-stroke, piston displacement-type calibrator and a pulsed output flowmeter. It is concluded that, given these equations and proper instrumentation of this type of calibrator, very high levels of performance can be attained and, in turn, these can be used to achieve high fluid flow rate measurement accuracy with pulsed output flowmeters.     

Undoped InP/InGaAs heterostructure insulated-gate FET's grown byOMVPE with PECVD-deposited SiO2 as gate insulator

The fabrication and performance of InP/InGaAs insulated-gate FETs which use a heterojunction to isolate the channel electrons from the semiconductor-insulator interface are discussed. Plasma-enhanced chemical vapor deposition (PECVD) was used to deposit SiO₂ on InP to form the gate insulator. Since the device structure is undoped, channel electrons are accumulated by the gate-induced field across the insulator. Extrinsic transconductances of 130 mS/mm (300 K) and 210 mS/mm (77 K) were achieved for 1.5- μm gate-length devices. Gate-drain breakdown voltages in excess of 20 V were also measured     

0.33-μm gate-length millimeter-wave InP-channel HEMTs with highf1 and fmax

The fabrication of 0.33-μm gate-length AlInAs/InP high electron mobility transistors (HEMTs) is reported. These InP-channel devices have f_t values as high as 76 GHz, f_max values of 146 GHz, and maximum stable gains of 16.8, 14, and 12 dB at 10, 18, and 30 GHz, respectively. The extrinsic DC transconductances are as high as 610 mS/mm; with drain-source breakdown voltages exceeding 10 V. The effective electron velocity in the InP channel is estimated to be at least 1.8×10⁷ cm/s, while the f_tL_g product is 29 GHz-μm. These results are comparable to the best reported results for similar InGaAs-channel devices     

The dependence of the electrical and optical properties of molecular beam epitaxial Ino.52Alo.48As on growth parameters: Interplay of surface kinetics and thermodynamics

The optical and transport properties of In_0.52Al_o.48As grown by molecular beam epitaxy have been studied as a function of growth temperature in the range of 300-520° C. It is evident that under our growth conditions, thermodynamic considerations become important, and combined with surface kinetics, clustering effects become most severe for growth temperatures around 400° C. The clustering effects are manifested by changes in low-temperature photoluminescence, Hall transport and in the properties of Schottky diodes made on the films and the relevant parameters show a peaking for growth at 400° C. In particular, the Hall mobility exhibits a turning point forT > 300 K, beyond which the mobility increases with increasing temperature. In addition, the Hall electron concentration exhibits an anomalous reduction in value in the same high-temperature range. Measurements were also made on In_0.52Al_0.48As grown at 620-650° C by metalorganic chemical vapor deposition. While these films exhibit the same turning point in Hall mobility, the reduction in carrier concentration is significantly absent. Analysis of these data therefore indicates that the turning point in the mobility, which is present for both growth techniques, is caused by small clusters (~35Å) of phases slightly different from the mean composition. The reduction in electron concentration, seen only in the molecular beam epitaxial samples, suggest a more severe phase separation. A simple analysis for the sample grown at 400° C indicates that the compositions In_0.60Al_0.40As and In_0.44Al_0.56As might be present, in addition to the mean lattice-matched composition.     

Advanced fuel elements for passive pressure tube light water reactors

This paper focuses on the development of advanced fuel elements for innovative pressure tube light water reactors. Considerations and constraints that affect the design process and various possible options are discussed. The two most promising fuel designs, which can survive a loss-of-coolant accident without primary coolant replenishment, while having sufficient margins to fuel design limits, are proposed, described and evaluated. It is demonstrated that this key objective can be achieved, provided that reliable SiC cladding or coating, which can withstand operating and accident conditions without failure, can be manufactured. Recent advances in ceramic coating technologies and experimental tests of coated specimens indicate that the attainment of this goal is feasible.