319 research outputs found
Modifying catalytically the soot morphology and nanostructure in diesel exhaust: Influence of silver De-NOx catalyst (Ag/Al2O3)
The influence of an Ag/Al2O3 HC-SCR catalyst on the morphological and nanostructural aspects of the exhaust particulate matter (PM) generated during the combustion of diesel fuel and a glycol ether–diesel fuel blend was addressed in this research work. In addition, the impact of in-cylinder fuel post injections (FPI) on the particulate formation pathway and on the catalytic de-NOx efficiency was also studied.
The tests were carried at low exhaust temperatures in the absence and presence of small amounts of hydrogen (H2). It is concluded that in the absence of H2, the catalyst does not modify the primary particle size (dp0) of the soot aggregates, while the aggregation of the soot particles throughout the catalyst channels is the main governing mechanism. The catalyst influence on the particulate structure was evident when H2 was introduced, with smaller dp0 seen downstream of the catalyst, indicating that despite the short residence time of the PM within the catalyst bed, the soot particles were partially oxidised. The use of late FPI reduces the exhaust PM level and delivers sufficient HC:NOx ratios that improves the catalyst activity up to a maximum of 80% NOx conversion, with no sign of catalyst deactivation when H2 (500 ppm) was injected. Furthermore, it is suggested that along with oxidising part of the particles produced during the main fuel injection phase, late FPI can also produce, to a lesser extent, some additional soot with a less matured structure, resulting on average in less ordered particles being emitted into the exhaust stream.
This work shows that in modern diesel engines, a silver catalyst can alter the soot structure in the exhaust in a way that can ease the diesel particulate filter (DPF) regeneration cycles, improve its filtration efficiency and help in effectively reducing the tailpipe NOx emissions. For the catalyst to perform these functions, multiple in-cylinder fuel injection strategies (late FPI) combined with small amounts of hydrogen addition to the exhaust are required
The Physiological Influence of Prostate size and Prostatic Specific Antigen (PSA) on The Concentrations of some Hormones and Biochemical Compounds for Males in Salah Alden Governorate
This study was conducted to investigate the effect of differencein prostate big size benign and prostate specific antigen (PSA) concentrations on some biochemical (Glucose , Cholesterol , Acid Phosphatase) and hormones(ACTH , Estrogen , Testosterone ) in the men patients having prostatic hyperplasia and compared with healthy men. The study was carried for 60 patients males infected by the prostatic hyperplasia and 40 healthy males, there ages were ranged between (47 – 90 years). The results show that high significant increased (P ≤0.05) in all patients categories(20 – 40 mm3), (41 – 60) ,( 61 – and more) mm3 of prostatic with BPH in the(Glucose, Cholesterol, Acid Phosphatase ACTH and estrogen) compared with a healthy men. There is significant (P ≤0.05) increased in the patients prostate size category of (61 – more mm3) compared with the otherpatients categories(20 – 40 mm3), (41 – 60 mm3) in the (Glucose , Acid Phosphatase , ACTH and estrogen) parameters , while the healthy men was increased significant (P ≤0.05) in the testosterone compared with all patients prostate size categories. On the other hand the all categories for the PSA concentrations (0-3.5) , (3.6-7.0), (7.1 and more) ng/ml are increase significant (P ≤0.05) in prostatic patients compared with healthy men in the components (Glucose , Cholesterol , Acid Phosphatase ACTH) and significant increase (P ≤0.05) in healthy testosterone compared with all PSA categories of prostatic patients. The high PSA category (7.1 and more)ng/ml gives the high concentrations in (Glucose, Cholesterol, Acid Phosphatase ACTH) and a significant effect (P ≤0.05) between the the patients categorie
Subclinical impairment of myocardial deformation displayed by speckle tracking imaging in patients with myotonic dystrophy type 1
Calidad de fruto y aceite de olivos maduros en condiciones de cultivo de secado parcial de la zona radical
This study was conducted to evaluate the quantitative and qualitative effects of partial rootzone drying (PRD) irrigation on olive trees and their fruit and oil quality. Olive trees of the Moroccan Picholine variety were grown under arid conditions in Marrakech, and exposed to four irrigation treatments: Control (irrigated with 100 % of the crop evapotranspiration, on the two sides of the root system), PRD1 (irrigated with 50 % of the control, on one side of the root system, switching every two weeks), PRD2 (irrigated with 50 % of the control, on one side of the root system, switching every four weeks) and PRD3 (irrigated with the same amount of water as the control applied on one side of the root system, switching every two weeks). The individual fruit weight, dimensions and oil contents were generally greater under PRD than the control. Whereas, the fruit water content was lower under PRD1 and PRD2 than the control and PRD3. Oil acidity was not affected by irrigation, while the total polyphenol content, which affects the oxidative stability and sensory characteristics of the oil, increased in response to the PRD irrigation, especially under PRD1 (246.0 ppm) and PRD2 (278.5 ppm) treatments, against 148.4 ppm and 101.8 ppm for PRD3 and the control respectively. This increase could explain the oil bitterness observed under PRD1 and PRD2. The fatty acid composition was not affected by PRD1 and PRD2. The oil quality based on UV absorption coefficients (K232 and K270) decreased significantly under PRD2. Chlorophyll content and maturity index were antagonistic, and olive ripeness was found to be precocious under PRD irrigation treatments compared to the control.Este estudio fue realizado para evaluar los efectos cuantitativos y cualitativos de la irrigación de olivos por secado parcial de la zona radical (PRD) sobre la calidad de su fruto y de su aceite. Los olivos de la variedad marroquà Picholine fueron cultivados en condiciones áridas en Marrakech, y expuestos a cuatro tratamientos de irrigación: Control (irrigado con el 100 % de la evapotranspiración de la cosecha, en los dos lados del sistema radical), PRD1 (irrigado con el 50 % del control, en sólo un lado del sistema radical, cambiando cada dos semanas), PRD2 (irrigado con el 50 % del control, en un lado del sistema radical, cambiando cada cuatro semanas) y PRD3 (irrigado con la misma cantidad del agua que el control aplicado en un lado del sistema radical, cambiando cada dos semanas). El peso individual del fruto, sus dimensiones y el contenido en aceite fueron generalmente mayores bajo PRD que en el control. Mientras que, el contenido de agua de la aceituna fue inferior en PRD1 y PRD2 que en el control y en PRD3. La acidez del aceite no se afectó por el régimen de irrigación, mientras que el contenido total de polifenoles, que afecta a la estabilidad oxidativa y a las caracterÃsticas sensoriales del aceite, aumentó en respuesta a la irrigación mediante PRD, sobre todo con los tratamientos PRD1 (246.0 ppm) y PRD2 (278.5 ppm), frente a los 148.4 ppm y 101.8 ppm de PRD3 y el control, respectivamente. Este aumento podrÃa explicar el amargor del aceite obtenida con PRD1 y PRD2. La composición de ácidos grasos no fue afectada por PRD1 Y PRD2. La calidad del aceite basada en los coeficientes de absorción UV (K232 y K270) disminuyó considerablemente con PRD2. El contenido de clorofila resultó antagonista del Ãndice de madurez, y éste último se desarrolló más precozmente en los tratamientos de irrigación PRD que en el control
A distributed optimization method for the geographically distributed data centres problem
The geographically distributed data centres problem (GDDC) is a naturally distributed resource allocation problem. The problem involves allocating a set of virtual machines (VM) amongst the data centres (DC) in each time period of an operating horizon. The goal is to optimize the allocation of workload across a set of DCs such that the energy cost is minimized, while respecting limitations on data centre capacities, migrations of VMs, etc. In this paper, we propose a distributed optimization method for GDDC using the distributed constraint optimization (DCOP) framework. First, we develop a new model of the GDDC as a DCOP where each DC operator is represented by an agent. Secondly, since traditional DCOP approaches are unsuited to these types of large-scale problem with multiple variables per agent and global constraints, we introduce a novel semi-asynchronous distributed algorithm for solving such DCOPs. Preliminary results illustrate the benefits of the new method
Advanced Catalytic Technologies for Compressed Natural Gas–Gasoline Fuelled Engines:Challenges in methane abatement
Advancing treatment of retinal disease through in silico trials
Abstract
Treating retinal diseases to prevent sight loss is an increasingly important challenge. Thanks to the configuration of the eye, the retina can be examined relatively easily in situ. Owing to recent technological development in scanning devices, much progress has been made in understanding the structure of the retina and characterising retinal biomarkers. However, treatment options remain limited and are often of low efficiency and efficacy.&#xD;&#xD;In recent years, the concept of in silico clinical trials has been adopted by many pharmaceutical companies to optimise and accelerate the development of therapeutics. In silico clinical trials rely on the use of mathematical models based on the physical and biochemical mechanisms underpinning a biological system. With appropriate simplifications and assumptions, one can generate computer simulations of various treatment regimens, new therapeutic molecules, delivery strategies and so forth, rapidly and at a fraction of the cost required for the equivalent experiments. Such simulations have the potential not only to hasten the development of therapies and strategies but also to&#xD;optimise the use of existing therapeutics.&#xD;&#xD;In this paper, we review the state-of-the-art in in silico models of the retina for mathematicians, biomedical scientists and clinicians, highlighting the challenges to developing in silico clinical trials. Throughout this paper, we highlight key findings from in silico models about the physiology of the retina in health and disease. We describe the main building blocks of in silico clinical trials and identify challenges to developing in silico clinical trials of retinal diseases.</jats:p
Severe neurologic syndrome associated with Middle East respiratory syndrome corona virus (MERS-CoV)
Quantifying the contribution of intracranial pressure and arterial blood pressure to spontaneous tympanic membrane displacement
Objective: Although previous studies have shown associations between patient symptoms/outcomes and the spontaneous tympanic membrane displacement (spTMD) pulse amplitude, the contribution of the underlying intracranial pressure (ICP) signal to the spTMD pulse remains largely unknown. We have assessed the relative contributions of ICP and arterial blood pressure (ABP) on spTMD at different frequencies in order to determine whether spTMD contains information about the ICP above and beyond that contained in the ABP. Approach: Eleven patients, who all had invasive ICP and ABP measurements in situ, were recruited from our intensive care unit. Their spTMD was recorded and the power spectral densities of the three signals, as well as coherences between the signals, were calculated in the range 0.1–5 Hz. Simple and multiple coherences, coupled with statistical tests using surrogate data, were carried out to quantify the relative contributions of ABP and ICP to spTMD. Main results: Most power of the signals was found to predominate at respiration rate, heart rate, and their harmonics, with little outside of these frequencies. Analysis of the simple coherences found a slight preference for ICP transmission, beyond that from ABP, to the spTMD at lower frequencies (7/11 patients at respiration, 7/10 patients at respiration 1st harmonic) which is reversed at the higher frequencies (2/11 patients at heart rate and its 1st harmonic). Both ICP and ABP were found to independently contribute to the spTMD. The multiple coherence reinforced that ICP is preferentially being transmitted at respiration and respiration 1st harmonic. Significance: Both ABP and ICP contribute independently to the spTMD signal, with most power occurring at clear physiological frequencies—respiration and harmonics and heart rate and harmonics. There is information shared between the ICP and spTMD that is not present in ABP. This analysis has indicated that lower frequencies appear to favour ICP as the driver for spTMD
Pulsatile tympanic membrane displacement is associated with cognitive score in healthy subjects
To test the hypothesis that pulsing of intracranial pressure has an association with cognition, we measured cognitive score and pulsing of the tympanic membrane in 290 healthy subjects. This hypothesis was formed on the assumptions that large intracranial pressure pulses impair cognitive performance and tympanic membrane pulses reflect intracranial pressure pulses. 290 healthy subjects, aged 20–80 years, completed the Montreal Cognitive Assessment Test. Spontaneous tympanic membrane displacement during a heart cycle was measured from both ears in the sitting and supine position. We applied multiple linear regression, correcting for age, heart rate, and height, to test for an association between cognitive score and spontaneous tympanic membrane displacement. Significance was set at P < 0.0125 (Bonferroni correction.) A significant association was seen in the left supine position (p = 0.0076.) The association was not significant in the right ear supine (p = 0.28) or in either ear while sitting. Sub-domains of the cognitive assessment revealed that executive function, language and memory have been primarily responsible for this association. In conclusion, we have found that spontaneous pulses of the tympanic membrane are associated with cognitive performance and believe this reflects an association between cognitive performance and intracranial pressure pulses
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