Compact high energy x-ray spectrometer based on forward Compton scattering for high intensity laser plasma experiments.

This article describes the design and presents recent results from testing and calibration of a forward Compton scattering high energy X-ray spectrometer. The calibration was performed using a bremsstrahlung source on the photon scattering facility at the γ Electron linac for beams with high brilliance and low emittance accelerator at Helmholtz-Zentrum Dresden-Rossendorf, which provides high energy X-ray photons with energies up to 18 MeV. The calibration was conducted at different bremsstrahlung end point energies-10.5, 13, 15, and 18 MeV. Experimental spectra show a systematic increase in the maximum energy, photon temperature, and flux. The spectrometer is effective for an energy range of 4-20 MeV with 20%-30% energy resolution. The spectrometer operates in low vacuum with pressure less than 0.1 mbar. Experimental tests showed that operating such a spectrometer in air causes a spuriously enhanced high energy signal due to Compton scattering of photons within air. The article also describes the design and shielding considerations which helped to achieve a dynamic range greater than 30 with this spectrometer. The comparison between the experimental results and Monte Carlo simulations are also presented.

Study of the prophylactic effect of droperidol, alizapride, propofol and promethazine on spinal morphine-induced pruritus.

BACKGROUND: We have compared the use of alizapride, propofol, droperidol and promethazine for the prevention of spinal morphine-induced pruritus. METHODS: Three hundred ASA I or II women undergoing Caesarean section under spinal anaesthesia, in which morphine 0.2 mg was added to a local anaesthetic, were assigned randomly to receive i.v., in the operating room, just after delivery of the baby, alizapride 100 mg, propofol 20 mg, droperidol 1.25 mg, promethazine 50 mg or saline 2 ml (control group). In the postoperative period, the women were assessed for pruritus (absent, mild, moderate or severe) or other untoward symptoms by blinded observers. We used 95% confidence limits (95% CI) for the cumulative incidence of moderate and severe pruritus to compare the groups, and the NNT and 95% CI to compare droperidol, propofol and alizapride as for their effectiveness in preventing pruritus. For other untoward effects, the chi(2)-test was used, results being considered significant when P<0.05. RESULTS: The droperidol, propofol and alizapride groups had significantly lower incidences of pruritus compared with the control and promethazine groups, while the incidence of pruritus was similar among the patients assigned to the promethazine and control groups. As for the prevention of moderate and severe pruritus, droperidol had the lowest NNT (3.52; 95% CI: 3.37-3.67), followed by propofol (4.61; 95% CI: 4.45-4.77) and alizapride (5.43; 95% CI: 5.27-5.59). As for untoward effects, droperidol and promethazine increased the incidence of somnolence, which seemed more severe with promethazine. Otherwise, there were no differences between the groups. CONCLUSION: Droperidol, propofol and alizapride, in a decreasing order of effectiveness in the doses used in this study, reduced the incidence of pruritus induced by the use of morphine 0.2 mg intrathecally. On the other hand, promethazine 50 mg was shown to be ineffective.

Propagation of fatigue cracks in acrylic bone cements containing different radiopaque agents.

In this work three iodine-containing monomers were proposed as new radiopaque agents for acrylic bone cements. In previous studies the addition of iodine-containing methacrylate monomers provided a statistically significant increase in tensile stress, fracture toughness and ductility, with respect to the barium sulphate (BaSO4)-containing cement. However, since fatigue resistance is one of the main properties required to ensure a good long-term performance of permanent prostheses, it is important to compare the fatigue properties of these new bone cement formulations with the radiolucent and BaSO4-containing bone cements. Because the acrylic cements have initial cracks, fatigue crack propagation studies were performed. It can be observed that these acrylic cements followed the Paris-Erdogan model. The results showed that the addition of some organic radiopacifiers (DISMA, TIBMA) increased the fatigue crack propagation resistance as compared to the radiolucent cement, being similar to the BaSO4-containing cement. The radiolucent cement showed a low crack propagation resistance.

Zirconia-toughened hydroxyapatite ceramic obtained by wet sintering.

A toughened hydroxyapatite (HA) ceramic has been obtained through the incorporation of magnesia partially stabilized zirconia (Mg-PSZ) under uniaxial pressing and sintering in wet oxygen at 1250 degrees C for 4 h. The powder X-ray diffraction (XRD) patterns and infrared spectra (FT-IR) show that HA is the only calcium phosphate phase present. The composite (MgPSZ-HA) has a density of 94% the theoretical value. The bending strength and the fracture toughness are around 50% higher for Mg-PSZ reinforced than for HA. The grain size and the fracture surface were studied by scanning electron microscopy (SEM). The influence of the Mg-PSZ particles on the fracture mechanism of the HA ceramic is discussed.

Improvement of the mechanical properties of acrylic bone cements by substitution of the radio-opaque agent.

Acrylic bone cements become radio-opaque by the addition of an inorganic compound, commonly BaSO4 or ZrO2. However, the use of these additives has some negative effects such as loss of mechanical properties, risk of release and bone resorption. The use of the monomer 2,5-diiodo-8-quinolyl methacrylate (IHQM), which shows adequate polymerization and radio-opacity properties, is proposed as a new X-ray opaque, methacrylate iodine-containing agent. The aim of this study is to determine the effect of this new radio-opaque agent on the mechanical properties of acrylic bone cements. The addition of the iodine-containing methacrylate provides a statistically significant increase in the tensile strength, fracture toughness and ductility, with respect to the barium sulphate-containing cement. This effect can be attributed to the fact that the use of a radio-opaque monomer eliminates the porosity associated with the barium sulfate particles, which show no adhesion to the matrix. However, some reinforcing effect must also be attributed to the iodine-containing monomer, since the tensile and fracture toughness values reached are even higher than those shown by the radiolucent cement.

Anticuerpos monoclonales de ratón contra la proteína gag 24 del Virus de la Inmunodeficiencia Humana Tipo I (VIH-1) / Mouse monoclonal antibodies against the gag 24 protein of the human immunodeficient virus type I (HIV-1)

El desarrollo de sistemas que permiten la cuantificación de la proteína gag 24 del VIH-1 puede ser de importancia en el pronóstico de la evolución de pacientes con SIDA, y en el monitoreo de la producción de antígeno natural y recombinante. En este trabajo se reporta la generación de un panel de anticuerpos monoclonales (AcM), a través de la fusión de esplenocitos de ratones inmunizados con el antígeno recombinante y el mieloma SP2/O/Ag14. Se han caracterizado cinco AcM provenientes de clones secretores estables. La especificidad de los anticuerpos por la gag 24 fue confirmada por ELISA, inmunofluorescencia indirecta y Western Blot. Uno de los cinco AcM reconoce, además, la cepa SBL6669 del VIH-2 en ELISA. Finalmente se demostró que el suero de un individuo infectado con VIH-1 inhibe la unión de AcM 197 a la gag 24 adsorbida a placas de poliestireno (AU)

Anticuerpos monoclonales de ratón contra la proteína gag 24 del Virus de la Inmunodeficiencia Humana Tipo I (VIH-1) / Mouse monoclonal antibodies against the gag 24 protein of the human immunodeficient virus type I (HIV-1)

El desarrollo de sistemas que permiten la cuantificación de la proteína gag 24 del VIH-1 puede ser de importancia en el pronóstico de la evolución de pacientes con SIDA, y en el monitoreo de la producción de antígeno natural y recombinante. En este trabajo se reporta la generación de un panel de anticuerpos monoclonales (AcM), a través de la fusión de esplenocitos de ratones inmunizados con el antígeno recombinante y el mieloma SP2/O/Ag14. Se han caracterizado cinco AcM provenientes de clones secretores estables. La especificidad de los anticuerpos por la gag 24 fue confirmada por ELISA, inmunofluorescencia indirecta y Western Blot. Uno de los cinco AcM reconoce, además, la cepa SBL6669 del VIH-2 en ELISA. Finalmente se demostró que el suero de un individuo infectado con VIH-1 inhibe la unión de AcM 197 a la gag 24 adsorbida a placas de poliestireno