Quasi-monochromatic x-rays for diagnostic radiology

Monochromatic x-ray beams are desirable in various fields of diagnostic radiology; in fact a reduction of the dose and an enhancement of the contrast could be achieved. In this work two different methods to monochromatize x-ray beams produced by conventional tubes have been compared. In the first one the beam is obtained via Bragg diffraction on mosaic crystal and in the second one by attenuating the polychromatic beam with aluminium filters. We have simulated quasi-monochromatic x-ray spectra by setting suitable values of Bragg's angle to obtain beams tuned to 20, 30, 40 and 50 keV with the SHADOW code, an x-ray tracing program designed to study the propagation and the interaction of a photon beam through an optical system. We have validated such a program by comparing some calculated data with measurements carried out on an experimental apparatus. Attenuated polychromatic x-ray spectra have been simulated by setting appropriate values of aluminium filters and potential with the SPECTRUM PROCESSOR, the software version of the Catalogue of Spectral Data for Diagnostic X-Rays, which provides radiographic x-ray spectra that can be attenuated with several material filters. The relation between the energy resolution and the flux as a function of the mean energy has been investigated and results have been compared. Results show that quasi-monochromatic x-ray beams produced via Bragg diffraction exhibit, for a given mean energy and energy resolution, a higher total flux compared to attenuated spectra.     

Effect of garlic and cabbage on healing of gastric ulcer in experimental rats

The effect of garlic (Allium sativum) and cabbage (Brassica oleracea var. capitata) extracts on the healing of gastric ulcer in experimental rats has been investigated. Thirty-three albino male rats (115 ± 4 g B.Wt. each) were used and divided into 6 groups (n = 6 rats); one was used as a negative control while the others were given aspirin orally (200 mg/kg B.Wt.). One of these groups was employed as a positive control and the others were administrated with 150 or 300 mg/kg B.Wt. doses of garlic and cabbage juice for 7 days. The length of the gastric ulcer, the volume of gastric juice, the total acidity, the pH value, the total bacterial count, and the histopathological changes of the stomach were examined. Results revealed that oral administration with both tested plant extracts reduced the length of gastric ulcer, the total acidity, the volume of gastric juice, the bacterial count, and the histopathological changes caused by aspirin. On the other hand, both aqueous plants extract increased the pH value of gastric juice. It is concluded that, garlic and cabbage extract could be used for healing acute gastric ulcer.     

Unraveling the microstructural and optoelectronic properties of solution-processed Pr-doped SrSnO3 perovskite oxide thin films

The inorganic stannous-based perovskite oxide SrSnO₃ has been utilized in various optoelectronic applications. Facilitating the synthesis process and engineering its properties, however, are still considered challenging due to several aspects. This paper reports on a thorough investigation of the influence of rare-earth (praseodymium) doping on the microstructural and optoelectronic properties of pure and Pr-doped SrSnO₃ perovskite oxide thin films synthesized by a two-step simple chemical solution deposition route. Structural analysis indicated the high quality of the obtained phase and the alteration generated from the insertion of impurities. Surface scanning illustrated the formation of homogenous and crack-free SrSnO₃ thin films with a nanorod morphology, with an augmentation in size as the dopant ratios increased. Optical properties analysis showed an enhancement in the samples optical absorption with wide-range bandgap tuning. First-principles calculations revealed the exchange interactions between the 3d–4f states and their impact on the electronic properties of the pristine material. Hall-effect measurements revealed an immense decrement in the resistivity of the films upon increment of doping ratios, passing from 7.3 × 10⁻² Ω cm for the undoped sample to 4.8 × 10⁻² Ω cm for 7% Pr content, while a reverse trend was observed on the carrier mobility, rising from 2.5 to 7.6 cm² V⁻¹ s⁻¹ for 7% Pr content. The results emphasized the efficiency of the simple synthesis route to produce high-quality samples. The current findings will contribute to paving the way towards expanding the utilization of simple and cost-effective chemical solution deposition methods for the fast and large area growth of stannous-based perovskite oxides for optoelectronic applications.

Unraveling the optical, electronic and electrical properties of high-quality nanorod morphology spray-coated Pr-doped SrSnO₃ perovskite oxide thin films.     

Revealing the impact of strontium doping on the optical,electronic and electrical properties of nanostructured 2H-CuFeO2 delafossite thin films

Delafossite materials are considered to be a promising range of transparent conductive oxides for optoelectronic applications. The complications that have held back their implementation in practical devices lie in the complex growth methods that are required and in the formation of undesirable secondary phases. Herein, a fast, simple, and low-cost deposition method allowing the deposition of high-quality 2H-CuFeO₂ nanostructured thin films is employed. The effect of Sr doping on the properties of spray-coated CuFeO₂ thin film annealed at 850 °C is reported. X-ray diffraction (XRD) analysis revealed the delafossite structures of all the samples corresponding to the 2H-CuFeO₂ phase. The lattice spacing decreased with increasing substitution of Sr at the Cu site. Raman analysis further authenticated the structural results collected via XRD analysis. Surface scanning using field-emission scanning electron microscopy revealed the formation of nanostructured CuFeO₂ thin film possessing high crystalline quality, with the nanocrystal size increasing as the dopant content was increased. Energy-dispersive X-ray analysis allowed the quantification of the elements content via determining the ratios of the main elements as well as the dopant content in each sample. The optical properties of the samples showed strong light absorption in the visible region with a decrease in the band gap values with Sr insertion. First-principles calculations using density functional theory (DFT) were conducted to strengthen the experimental findings regarding the nature of the bonds in the hexagonal lattice of the CuFeO₂ compound and the effect of Sr doping on its characteristics. The electrical properties measured at room temperature revealed p-type conductivity with tunable resistivity, while the samples displayed increased electron mobility as a function of the dopant content. Consequently, our work introduced an efficient and cost-effective synthesis route for the preparation of high-quality nanostructured 2H-CuFeO₂ thin films, paving the way to facilitate further device applications.

Facile synthesis of the challenging 2H-CuFeO₂ delafossite nanostructured thin films is reported, and the effect of Sr doping is revealed experimentally and theoretically.     

血清N端脑钠肽前体和降钙素原水平在脓毒症患者中的表达及相关性分析

目的 探讨血清N末端脑钠肽前体(NT-pro BNP)和降钙素原(PCT)水平在脓毒症患者中的表达水平及相关性.方法 采集120例脓毒症患者和40例健康志愿者(对照组).脓毒症患者按病情严重程度分为一般脓毒症组、严重脓毒症组、脓毒症休克组,每组各40例.按患者入院28 d后预后情况,又分为存活组和死亡组.记录血清NT-pro BNP、PCT水平及急性生理和慢性健康状况(APACHE-Ⅱ)评分.结果 与对照组相比,脓毒症各组的血清NT-pro BNP、PCT水平均明显增高,差异有统计学意义(P<0.05);随着脓毒症病情的加重,血清NT-pro BNP、PCT水平和APACHEⅡ评分明显升高,一般脓毒症组、严重脓毒症组、脓毒症休克组两两比较,差异有统计学意义(P<0.05).死亡组患者的血清PCT、NT-pro BNP水平和APACHEⅡ评分明显高于存活组,差异有统计学意义(P<0.05).血清NT-pro-BNP灵敏度和特异度为81.34%、86.27%,PCT为83.08%、88.61%.血清NT-proBNP水平和血清PCT水平呈正相关(r=0.826,P<0.05),血清NT-proBNP水平与APACHEⅡ评分呈正相关(r=0.756,P<0.05),血清PCT水平与APACHEⅡ评分也呈正相关(r=0.702,P<0.05).结论 血清NT-pro BNP和PCT水平对脓毒血症患者病情程度和生存情况的预测评估具有重要的临床应用价值.     

Tracheotomy or prolonged tracheal intubation for long-term ventilation

130 critically ill patients undergoing long term mechanical ventilation were divided into two groups, tracheotomy versus translaryngeal intubation. There were no difference in demographic characteristics between the two groups. The incidence of chronic obstructive pulmonary disease (COPD) was also higher in T. The tracheotomy was achieved at mean within 14 days after the beginning of mechanical ventilation. The incidence of pneumonia is the same in the two groups (41% for T versus 39% for I). The length of mechanical ventilation is longer in T (25 +/- 12 d versus 12 +/- 4 d). The COPD represent a risk factor for prolonged mechanical ventilation in T (18 days in COPD patients with tracheotomy versus 9 days in non COPD patients). The length of stay in intensive care unit is higher in T (29 +/- 13 d versus 15 +/- 4 d). The 28th day mortality is similar between the two groups. The tracheotomy didn't allow a shorter duration of mechanical ventilation. That's can be explain by the fact that we performed the tracheotomy in a high risk population for pulmonary complications (COPD) and often after a first failure of weaning form mechanical ventilation.     

Spatial resolution measurements in quasimonochromatic x rays with mosaic crystals for mammography application

A novel x-ray source for mammography application is being investigated. Quasimonochromatic x rays have been produced via Bragg diffraction with a W-anode x-ray tube and a graphite mosaic crystal array. The system provides 18 keV x rays with an energy resolution deltaE/E approximately equals 0.12. A thorough analysis of the spatial resolution of the system has been performed in order to understand and quantify the effect of the introduction of an active optical element such as a mosaic crystal in the x-ray path. The focal spot of the source and its emission properties have been studied by using the slit camera method. Experiments have shown that the introduction of a mosaic crystal in the optical path modifies the resolution properties of the Bragg diffraction-based radiography system. Along the direction perpendicular to the diffraction plane the resolution properties of the imaging system mainly depend on the x-ray tube focal spot size and position. Along the diffraction plane the focal spot size depends on mosaic characteristics and on the geometrical setup. Hence, it could be modified by setting the appropriate experimental conditions.