688 research outputs found
Laser ignition of elastomer-modified cast double-base (EMCDB) propellant using a diode laser
An experimental study was conducted to investigate laser ignition using a diode laser for elastomer-modified cast double-base (EMCDB) propellant in order to develop more liable and greener laser ignitors for direct initiation of the propellant. Samples of the propellant were ignited using a 974 nm near-infrared diode laser. Laser beam parameters including laser power, beam width and pulse width were investigated to determine their effects on the ignition performance in terms of delay time, rise time and burn time of the propellant which was arranged in several different configurations. The results have shown that the smaller beam widths, longer pulse widths and higher laser powers resulted in shorter ignition delay times and overall burn times, however, there came a point at which increasing the amount of laser energy transferred to the material resulted in no significant reduction in either delay time or overall burn time. The propellant tested responded well to laser ignition, a discovery which supports continued research into the development of laser-based propellant ignitors
Improving gasoline direct injection (GDI) engine efficiency and emissions with hydrogen from exhaust gas fuel reforming
Thermochemical recovery technology for improved modern engine fuel economy – part 1: analysis of a prototype exhaust gas fuel reformer
Exhaust gas fuel reforming has the potential to improve the thermal efficiency of internal combustion engines, as well as simultaneously reduce gaseous and particulate emissions.</p
Validation of a gas chromatography-mass spectrometry method for the analysis of sterol oxidation products in serum
A validated gas chromatography-mass spectrometry (GC-MS) detection method for the quantitative analysis of sterol oxidation products (SOPs) in serum is described. After a lipid extraction procedure with chloroform-methanol, a cold saponification and purification by solid phase extraction, oxysterols were derivatized to form trimethyl-sylil-ethers which were subjected to GC-MS analysis. Calibration curves for cholesterol oxidation products showed determination coefficient (R(2)) of 1.0, with low values for the coefficient of variation of the response factors (< 1%). Detection and quantification limits were below 5 ng/mL and 10 ng/mL, respectively. Recovery data were between 77.65% and 110.29% (CV < 10% for all compounds). Good results were obtained for within- and between-day repeatability, with values below 10%. In conclusion, the method performed is suitable for the determination and quantification of SOPs in serum
Adipose-Derived Stem Cells in Crohn's Rectovaginal Fistula
Therapeutic options for recto-vaginal fistula in the setting of Crohn's disease are limited and many data are available in the literature. The manuscript describes the history of a patient who has been the pioneer of our Clinical Trials in treating this disease in fistulizing Crohn's disease environment. We believe it is the first time that a patient with this disease has been treated by adipose-derived stem cells in allogeneic form. The conclusion of our study with Mary is that the use of mesenchymal stem cells derived from adipose tissue is secure, either in autologous or allogeneic form. Furthermore, we have proved that if we use multi-dose and multiple applications on a patient, it does not produce any adverse effect, which confirms us the safety of using these cells in patients at least in the fistulizing Crohn's disease environment
Tribological Performance of Biomass-Derived Bio-Alcohol and Bio-Ketone Fuels
This study relates to developing future alternative fuels and focuses on the effects of a fuel’s molecular structure on its properties and performance in advanced propulsion systems. The tribological performance of various biomass-derived oxygenated alternative fuels, including butanol, pentanol, cyclopentanol, cyclopentanone, and gasoline and their blends with diesel, was investigated. Lubricity tests were conducted using a high-frequency reciprocating rig (HFRR). Cyclopentanone-diesel and cyclopentanol-diesel blends result in smaller wear scar sizes compared to using their neat forms. A lower steel disc contaminated with the alternative fuels during the HFRR tests resulted in worn surface roughness values lower than those of the neat diesel by up to 20%. It is believed that these reductions are mainly due to the presence of the hydroxyl group and the carbonyl group in alcohols and ketones, respectively, which make them more polar and consequently helps the formation of the protective lubrication film on the worn moving surfaces during the sliding process. Overall, the results from this study indicate that environmentally friendly cyclopentanol and cyclopentanone are practical and efficient fuel candidates for future advanced propulsion systems
Los derechos humanos al medio ambiente adecuado y a su protección
La fábula de Esopo, conocida también en las versiones dadas
por La Fontaine y Samaniego, explica con lucidez las relaciones
entre el ser humano y el planeta Tierra. Conocidas las limitaciones de éste último, sólo una estulticia inexplicable puede llevar
a aquél a sobrexplotar sus recursos hoy, ajeno a las consecuencias
que esto tendrá mañana. La conciencia generalizada de que se
está llevando a cabo un modo de desarrollo fundado en principios análogos a los que determinaron la conducta del dueño de la
gallina de los huevos de oro ha impulsado una respuesta cada vez
más vigorosa de la sociedad para reconducir este estado de cosas.
El Derecho está siendo sensible a esta nueva demanda social y
está dando paulatinamente respuestas jurídicas a los interrogantes
ambientales. De entre todas ellas quizá la de mayor relevancia
teórica es la que concibe él medio ambiente adecuado como un
derecho humano
Treatment of heart failure with autologous skeletal myoblasts
The management of patients with heart failure
is a daily challenge for cardiologists and cardiac surgeons.
Pharmacotherapy, atrio-biventricular resynchronization, myocardial
revascularization, valve repair techniques, latissimus
dorsi cardiomyoplasty, acorn cardiac support device, heart
transplantation and mechanical assist devices do not cover all the needs. The recent progress in cellular and molecular biology
allows the development of new therapies for heart failure.
Transplantation of Autologous Cells: One of the most innovative
consists in the transplantation of autologous ex-vivo expanded
cells into the myocardium for heart muscle regeneration.
This approach is called “cellular cardiomyoplasty”
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