Study of Scattering and Polarization of Light in Biological Tissue

Tkáňová optika nabývá rychle na významu a přesná znalost optických vlastností biologických tkání je podstatná pro výzkum v biomedicíně i pro kontrolu kvality potravin. Jestliže je vzorek tkáně osvětlen, dochází k mnohonásobnému odrazu světla. V případě postmortem neživých tkání (maso) je rozměr buněk větší než vlnová délka použitého světla. Dochází k Mieovu rozptylu prošlého nebo zpět odraženého světla, v důsledku čehož se objevují různé polarizační stavy světla. Polarizační stavy světla rozptýleného na difúzním prostředí jsou experimentálně zkoumány a modelovány. V práci jsme provedli dva modifikované experimenty: rozptyl polarizovaného světla, které dvakrát prochází vzorkem (vpřed a vzad) a jen světla, které jen prochází vzorkem. Měření rozptýleného světla ukazuje, že dochází k depolarizaci a ke stáčení polarizační roviny, což obojí závisí na orientaci svalových vláken a stárnutí tkání postmortem. Mimo experimentů byl také proveden teoretický popis difúzní biologické tkáně a byla vypočtena radiační přenosová rovnice pomocí modifikované Monte Carlo metody, která zahrnuje polarizační stav světla (PLMC). Je ukázáno, že stupeň polarizace podstatně závisí na optických vlastnostech rozptylového prostředí. Výsledky ukazují, že stav polarizace světla na výstupu závisí na stavu polarizace světla před vzorkem a na optických vlastnostech a tloušťce vrstvy prostředí v průběhu jejího stárnutí. Je také provedena korelace změn polarizace na čerstvosti masa, i popis dynamického chování polarizace při stárnutí masa.Tissue optics becomes a rapidly expanding field of great interest and a precise knowledge of optical properties of biological tissues is essential for biomedical investigation and food quality control. If the sample of tissue is illuminated, the multiple scattering occurs. In the case of the postmortem tissue (meat) the cell dimensions are larger than the wavelength. Mie scattering of transmitted or reflected light arises and produces various polarization states. Polarization properties of light scattered from a scattering medium have been studied with experiments and modeling. Two modified experiments were performed: scattering of polarized light passing twice the sample (forward and backward) and only transmitted light. The measurements of scattered light display depolarization and rotation of polarized light, which depend both on orientation of the muscle fibers and ageing process of meat. Theoretical description of turbid biological tissue and computing of radiative transfer equation by modified Polarized Light Monte Carlo (PLMC) method has also been executed. It is shown that the degree of polarization is sensitive to the optical properties of the turbid medium. The results demonstrate that polarized light scattered from a scattering medium is sensitive to the state of input polarization and the optical properties and thickness of the tissue during the ageing. The correlations of polarization changes and freshness of meat, as well as dynamic behavior of the polarization in ageing meat are shown.

Hydrodynamics, Mixing, and Mass Transfer in Bubble Columns with Internals

Bubble columns and slurry bubble columns are considered reactors of choice for a wide range of applications in the chemical, biochemical, and petrochemical industries. Most of the chemical applications of bubble columns include exothermic processes and hence they require some means of heat removal to maintain a steady process. The most practical means for heat removal in these reactors is the utilization of vertical cooling internals since they provide high heat transfer area per reactor volume. However, the effects of these internals on the reactor performance are poorly understood in the open literature. This causes the design of the internals to be based on empirical rules not on the applications of fundamentals. The main objective of this study is to enhance the understanding of the effects of vertical cooling internals on the gas hydrodynamics, gas mixing, and mass transfer. In addition, this study attempts to develop and validate models that can simulate the radial gas velocity profile and axial gas mixing in the presence and absence of internals. Finally, this work aims to validate all the observed experimental results and models in larger columns with and without internals to have a better understanding of the scale-up effects in the presence of internals. This is accomplished by carrying out experiments in a lab-scale 8-inch bubble column and a pilot-scale 18-inch bubble column in the absence and presence of internals. The studied % occluded area by internals: ~ 25%) is chosen to match the % occluded area used in the Fischer-Tropsch synthesis. The radial gas velocity profiles are measured using the 4-point optical probe and are used to validate the 1-D gas velocity model developed by Gupta: 2002). Gar tracer techniques are used to study the effect of internals on the overall axial gas mixing and mass transfer. A 2-D model, that considers the radial variations of the gas velocity and gas holdup, is developed and used to analyze the tracer data allowing the estimation of the turbulent diffusivities of the gas phase. The 2-D model along with the axial dispersion coefficient model developed by Degaleesan and Dudukovic: 1998) are used to determine the contribution of different mixing mechanisms to the overall axial gas mixing. The main findings of the current work can be summarized as follows: The effect of internals and column diameter on the gas velocity profile, gas mixing, and mass transfer is assessed. The presence of internals causes: An increase in the center-line gas velocity. A significant decrease in axial gas mixing. A decrease in the gas-liquid mass transfer coefficient. The increase in column diameter causes: Enhancement of the gas circulation. An increase in axial gas mixing. The model developed by Gupta: 2002) to predict radial gas velocity profiles is validated at different operating conditions in the presence and absence of internals. A 2-D convection-diffusion model is developed and proven useful in interpreting gas tracer data and simulating the overall axial gas mixing in the presence and absence of internals

Physiological investigations of the response of wheat (Triticum aestivum L.) to soil salinity

PhD ThesisA series of greenhouse and control environment experiments were carried out to study the response of some wheat cultivars (Triticum aestivum L. ) to soil salinity. The rate and percentage of seed germination were reduced by increasing soil salinity. The cultivar Falchetto was more tolerant in terms of germination than the other cultivars under saline conditions. Increasing salinity consistently reduced the growth and dry matter production of all wheat cultivars used. The most sensitive growth character to salinity was leaf area and tiller number while net assimilation rate was least sensitive and sometimes not affected by salinity. The retardation of growth under salt stress in this study may result from reduced leaf area for photosynthesis, but the cause of reduced leaf area is not clear. In all cultivars tested, grain yield and its components were reduced by increasing soil salinity (0 - 0.6% salt) or irrigation with saline water (0 - 4000 ppm salt). The most sensitive yield characters to salinity were spike number and grain number per spike while spike length and spikelet number per spike were less sensitive as compared with the other components. Falchetto and Shakha 62 were less sensitive than the other cultivars used in this study. Leaf proline content increased while leaf chlorophyll content decreased with increasing soil salinity. Also, leaf and stem content of sodium, calcium and magnesium increased with increasing salinity levels both in vegetative parts and in grains. Increasing soil salinity increased ash and protein content of wheat grains but decreased moisture and total carbohydrate content. Application of nitrogen fertilizer under saline conditions enhanced grain yield and its components and to some extent countered the adverse effect of soil salinity up to 0.4%. While added nitrogen did not increase growth and dry weight of wheat plant significantly, crop growth rate increased significantly. On the other hand spraying wheat crop with trace elements did not affect the growth and grain yield and its components except 1000 kernel weight under saline conditions. The interaction effect between salinity and some environmental factors was significant on germination and growth. Under saline and non-saline conditions increasing temperature from 10 to 20°C increased germination capacity and depressed it between 20 and 30°C. Also, increased relative humidity from 47 to 92% increased germination capacity. For vegetative growth, generally, increasing temperature up to 20°C, relative humidity from 47 to 92%, and available soil water content from 20 to 100% increased vegetative growth and dry matter production of wheat plant under saline and non-saline conditions. The interaction effect between salinity and presoaking with plant growth regulators (CCC, GA3, IAA and Kinetin) and salt solutions (Nacl and Cacl2 ) on germination and growth of wheat accelerated germination under saline and non-saline conditions. For some characters presoaking with these plant growth regulators or salt reduced the deleterious effect of salinity and improved plant performance at these early stages of growth under saline conditions. Water and osmotic potentials, total and relative water content (RWC) and transpiration rate decreased and stomatal number per microscope field increased with increasing soil salinity, but turgor potential was essentially unchanged by increasing soil salinity indicating osmotic adjustment. Also, it is evident from the water relations, PEG and RH experiments that ion toxicity effect operated in addition to the osmotic one during early stages of growthEgyptian Government

Selecting authentic audiovisual materials and designing authentic tasks in the AFL classroom: Criteria and challenges

This study investigated the criteria of selecting authentic audiovisual materials (AAM) and designing authentic tasks (AT) as well as the challenges which teachers of Arabic as a Foreign Language (AFL) encounter when selecting AAM and designing AT in the AFL classroom. Data collection procedures included an online questionnaire, classroom observations, and teachers’ interviews. Data collection followed this order: 112 respondents from various teaching backgrounds were surveyed, five AFL classrooms were observed, and four AFL instructors in a private university in Egypt were interviewed. Data was quantitatively and qualitatively analyzed. The results indicated that AFL teachers frequently use news, songs, and movies. The AFL teachers illustrated that AAM could be used at all levels, and they mainly use them to raise cultural awareness. Furthermore, results demonstrated that AFL teachers commonly follow specific criteria when selecting AAM and designing AT. Moreover, results illustrated that AFL teachers face challenges when selecting AAM and when designing AT. The task of finding AAM is difficult in terms of conducting the search, making a selection, and screening the vocabulary. On the other hand, the main challenges when designing AT include: effort, time, need for training, and preparation of appropriate activities to accurately measure learners’ levels. The results revealed that AFL teachers need training to select the suitable AAM for each level, to prepare an AAM-based curriculum, and to use technological tools. The results also demonstrated that AFL teachers lack a clear understanding of AT, which implies focusing on developing AFL teachers’ skills to effectively prepare AT. Such results, therefore, support the hypothesis that AFL teachers lack a clear understanding of AT. In response, certain pedagogical implications are proposed

Templated Hydroxyapatite Nucleation and Growth at Physiological Conditions onto Self-assembled Elastin-Like Nanoparticles.

Studying materials in the nanosize scale lead to develop new synthetic approaches and discover a lot of new properties, and therefore manipulating to develop new materials that are used for different applications. In the nanoscale, physics, chemistry, biology, material science and engineering converge toward the same principles and tools. In this work, nanoparticles that developed genetically have been used to form hydroxyapatites. Polymers such as elastin-like polymers can be manipulated by the bottom-up approach to form nanoparticles and also by top-down to form patterns in scales of nanometers on the polymer hydrogel. The first aim of this work is to synthesis a nanoparticles and characterizing it. These nanoparticles are synthesized from amphiphilic elastin-like copolymers that exhibit a lower critical solution temperature, (LCST), and under the effect of the environmental stimuli could show a transition from soluble phase to insoluble phase. Below this transition temperature, in aqueous solution, the polymers chains are hydrated and extended by the hydrophobic interaction. Above this transition temperature, the chains can be assembled to form a phase separated state and adopt a dynamic, regular and nonrandom structure. Due to the self-assembly properties of thess amphiphilic elastin-like polymers at low temperature, recombinant DNA genetic engineering has been used to recombine it with SNA15 fragment. The SNA15 fragment is the first fifteen amino acid from salivary protein statherin wherein the two phosphoserine amino acid residues at positions 2 and 3 have been substituted by L- aspartic acid. This fragment has a negative charge and a helical structure in all solvents that has a high affinity to nucleate and promote the crystallization of hydroxyapatites. The amphiphilic block copolymer has been recombined with three and six fragments of SNA15. These polymers have been characterized in ultra-pure deionized water by using differential scanning calorimetry and light scattering; furthermore, have been characterized in the solid state by Fourier Transform Infrared Spectroscopy (FTIR). The second aim of this work is using these nanoparticles as a template to form nanoparticles of calcium phosphates under physiological conditions. The elastin-like polymers assembled to nanoparticles that are able to form calcium phosphate in SBF at 37oC. Electron microscopy used to study the formed nanoparticles of calcium phosphate by performing electron diffraction and elemental analysis over the nanoparticles. Also, the calcium phosphates formed have been investigated using X-ray to identify the formed phases of calcium phosphate. Furthermore; the formed nanocalcium phosphates and its effect on polymer structure have been studied by FTIR spectroscopy.Física de la Materia Condensada, Cristalografía y MineralogíaMáster en Nanociencia y Nanotecnología Molecula

Event Based Retrieval From Digital Libraries Containing Data Streams

The objective of this research is to study the issues involved in building a digital library that contains data streams and allows event-based retrieval. “Digital Libraries are storehouses of information available through the Internet that provide ways to collect, store, and organize data and make it accessible for search, retrieval, and processing” [29]. Data streams are sources of information for applications such as news-on-demand, weather services, and scientific research, to name a few. A data stream is a sequence of data units produced over a period of time. Examples of data streams are video streams, audio stream, and sensor readings. Saving data streams in digital libraries is advantageous because of the services provided by digital libraries such as archiving, preservation, administration, and access control. Events are noteworthy occurrences that happen during data streams. Events are easier to remember than specific time instances at which they occur; hence using them for retrieval is more commensurate with human behavior and can be more efficient via direct accessing instead of scanning. The focus of this research is not only on storing data streams in a digital library and using event-based retrieval, but also on relating streams and playing them back at the same time, possibly in a synchronized manner, to facilitate better understanding in research or other working situations. Our approach for this research starts by considering digital libraries for: stock market, news streams, census bureau statistics, weather, sports games, and the educational environment. For each of these applications, we form categories of possible users and the basic requirements for each of them. As a result, we identify a list of design goals that we take into consideration in developing the architecture of the library. To illustrate and validate our approach we implement a medical digital library containing actual Computed Tomography (CT) scan streams. It also contains sample medical text and audio streams to show the heterogeneity of the library. Streams are displayed in a concise, yet complete, way that makes it unproblematic for users to decide whether or not to playback a stream and to set playback options. The playback interface itself is organized in a way that accommodates synchronous and asynchronous streams and enables users to control the playback of these streams. We study the performance of the specialized search and retrieval processes in comparison to traditional search and retrieval processes. We conclude with a discussion on how to adapt the library to additional stream types in addition to suggesting other future efforts in this area

Study of some physicochemical parameters in the water Of El-Bagouria Canal at El-Menoufia Governorate, Egypt

Background: Environmental pollution is one of the most serious problems facing humanity in the 20th century and still require great efforts at all levels. This is especially rivers are the main sources for drinking and irrigation.Objective: The present study was aimed to investigate some physicochemical parameters in the water at different sites of El-Bagouria Canal, El-Menoufia Governorate during the period of study.Materials and methods: Water samples were collected seasonally from the four stations during the year and stored for the final examination. Environmental factors and heavy metals concentrations were determined by using specific methods.Results: Spring showed the highest value of pH and turbidity, while autumn and winter showed the highest levels of electric conductivity, total dissolved solids, and chloride. However, alkalinity and total hardness were peaked during autumn. Statistically, there is strong positive correlation between pH, alkalinity with water temperatures, turbidity, (TDS) and total hardness with pH. The results indicated that the maximum levels of the concentrations of studied heavy metals in water were recorded during the hot season compared to the cold seasons. Correlation coefficient indicated that, a positive correlation between cadmium concentration in the water with lead, plus positive correlation between lead, copper with iron were present.Conclusion: It could be concluded that increased levels of physicochemical factors and heavy metal concentrations may pose a high risk to aquatic organisms and human health. So, the present study shows that precautionary measures must be taken to reduce pollution at the freshwater canals in the future

Fault-tolerant interconnection networks for multiprocessor systems

Interconnection networks represent the backbone of multiprocessor systems. A failure in the network, therefore, could seriously degrade the system performance. For this reason, fault tolerance has been regarded as a major consideration in interconnection network design. This thesis presents two novel techniques to provide fault tolerance capabilities to three major networks: the Baseline network, the Benes network and the Clos network. First, the Simple Fault Tolerance Technique (SFT) is presented. The SFT technique is in fact the result of merging two widely known interconnection mechanisms: a normal interconnection network and a shared bus. This technique is most suitable for networks with small switches, such as the Baseline network and the Benes network. For the Clos network, whose switches may be large for the SFT, another technique is developed to produce the Fault-Tolerant Clos (FTC) network. In the FTC, one switch is added to each stage. The two techniques are described and thoroughly analyzed