bluuebunny/crossref_metadata_2025 huggingface dataset:
Laboratory cultivation of Qatari Acropora: Studying dynamic factors that influence coral growth and photosynthetic efficiency
Authors: Al-Naema Nayla Mohammed , Richard Cecile , Saeed Suhur , Febbo Eric
Published: October 2012

Background:
The coral ecosystem in Qatar is very important as it provides a foundation habitat for many aquatic species. An extensive two-year field study was conducted to evaluate the effectiveness of pulse amplitude modulation (PAM) fluorometry in monitoring the health of sensitive ecosystems such as coral reefs along the coast of Qatar. The study demonstrated that PAM fluorometry can provide reliable and objective information on coral health in advance of visual signs of stress. The scope has now been expanded to include laboratory-based research.

Objectives:
The objectives of this research are: a) to establish a viable laboratory-based Qatari coral (Acropora sp.) culture system and b) to utilize laboratory-based imaging-PAM fluorometry to compile baseline data, and gain an understanding of environmental parameters that affect the health of the Qatari coral.

Methods:
Laboratory studies were initiated in December 2011; Acropora samples were collected from mother colonies in Umm Al-Arshan (north of Qatar); the 'nubbins' were cultured in pre-acclimatized laboratory aquaria. Imaging-PAM fluorometer was used to measure photosynthetic processes that were correlated to laboratory culture conditions. A wide range of water quality parameters have been measured, including: temperature, salinity, ammonia, nitrate, nitrite, phosphate, calcium and pH.

Results:
This research showed that it is possible to successfully culture Acropora coral; the initial colonies have grown to the point that several subsequent colonies have been produced to initiate laboratory assay development. The results of the imaging-PAM also show good correlation with the data obtained using the instrument used in the field.

Conclusion:
This study demonstrated for the first time the successful culture of Qatari Acropora in a laboratory setting in Qatar. The imaging-PAM fluorometer was also used to obtain detailed visual images of photosynthesis processes. Future studies include Acroproa eco-toxicological experiments to study contaminants that could affect the health of the corals around the Qatari coastal area.
Industrial low grade heat: A useful underused energy source
Authors: Benyahia Farid , Khraisheh Majeda , Adham Samer , Menawy Yahia , Fard Ahmad
Published: October 2012

The process industry utilizes thermal energy on a massive scale and rejects a significant proportion into the environment as a low grade heat. The definition of low grade heat is fuzzy and is somewhat related to the temperature of the stream carrying such thermal energy. Estimates of low grade heat emissions are hard to compile accurately on a global scale but these are likely to be of the order of thousands of trillions of BTUs. In some cases, up to 50% of thermal energy consumed is eventually rejected as low grade heat. This waste is not only uneconomical but also environmentally damaging since it carries a carbon footprint.

Modern process plants reduced a great deal of thermal energy losses through heat integration and energy recovery. However, due to process temperature requirements, a vast amount of thermal energy denoted as low grade heat is still rejected. The objectives of this work include evaluating the possibility of utilizing the low grade heat outside the process generating, in a useful manner that has both economic and environmental benefits. In the Middle East where the oil and gas industry rejects vast amounts of low grade heat, recovery and utilization for desalination is becoming a serious option. This work proposes utilization of low grade heat in membrane distillation for desalination and establishes a balance between capital and operating costs as well as carbon footprint reduction. The work is based on a couple of case studies involving well established processes, namely the vinyl chloride monomer and gas-to-liquids processes. The recovery of low grade heat will be coupled with seawater cooling thus providing a warm source of salty water feed to the membrane distillation system. The work indicated that quality potable water may be produced for the petrochemical plants and neighboring living quarters at a reasonable cost. This approach may reduce the demand for fresh water from desalination plants in major industrial complexes making these self-sufficient in fresh water. Benefits are both economic and environmental.
Room temperature ammonia gas sensor based on different acid-doped polyaniline-polyvinyl alcohol blends
Authors: Madi Nabil Kassem , Bhadra Jolly , Al-Thani Noora , Al-Maadeed Mariam A.
Published: October 2012

In the present work, we reported the performance of the gas sensor based on polyaniline-polyvinyl alcohol (PANI-PVA) thin-film to develop a usable sensor. The PANI-PVA were doped with camphorsulphonic acid (CSA), naphtalenesulfonic acid (NSA), dodecyl benzene sulfonic acid (DBSA) and p-toluene sulfonic acid (PTSA). CSA doped PANI nanocomposite sensors were fabricated on glass substrates by dripping and their gas sensing characteristics for ammonia (NH₃) were investigated at room temperature. PANI was prepared by the dispersion polymerization method. An appropriate amount of PANI and acid were mixed in a mortar and pestle. The mixture was dissolved in 100 mL of water, stirring at room temperature for 3 hours. The blend solution was then used to cast films on glass slides.

PANI-PVA blend films are characterized for surface as well as structural morphology SEM and XRD. The morphological analysis shows nanoparticle formation of different shapes depending upon the dopant types. The XRD pictures show some shorts of crystallinity in the blend films. The FTIR spectra show chemical crosslinking between the polymers. The thermal study reveals three steps of degradation of the polymer blends. The electrical properties studies are conducted by in-plane I-V characteristics, and four probe conductivity. We used our blend as an ammonia gas sensor. Among all four sensors the blend film doped with DBSA had good sensitivity and reversibility. This might be because of its enhanced surface morphology that facilitates good adsorption and desorption of ammonia gas on the surface and high conductivity.

In this study, ammonia gas sensors based on PANI-PVA composite films were prepared by a solution casting method. The composite films have been characterized by XRD, FTIR and SEM measurements. The SEM images have shown that PANI-PVA film has a different morphology based on the types of doping acids. The film presents significant resistivity upon exposure to ammonia gas at room temperature. It was found that these sensors are sensitive, stable, fast in response and easy to regenerate at room temperature. The advantages of this composite sensor compared to the pure PANI sensor are its fast regeneration associated with improved mechanical properties and chemical stability.
Role of aromatics and paraffinic hydrocarbons on synthetic jet fuels properties
Authors: Orillano Maria , Al-Nuaimi Ibrahim , Al-Mohandi Dhabia , Warrag Samah , Elbashir Nimir
Published: October 2012

With sponsorship from Qatar Science and Technology Park to support Qatar Airways' vision as a world leader in alternative fuels, our research team started work in this field in 2009 as part of a unique academia-industry collaboration model. The undergraduate student researchers are funded by Qatar National Research Fund and play a major role in this project, participating in all its experimental, computational, and theoretical phases.

Phase I of this work covers the development of correlations between the Gas-to-Liquid (GTL) synthetic jet fuels' building blocks (paraffinic hydrocarbons) and their physical properties (i.e. density, viscosity, flash point, freezing point, heat content, etc.). The objective of this phase was to identify optimum fuel characteristics and to meet aviation industry standards (e.g. ASTM D1655 & D7566). In Phase II, the experimental data were analyzed using sophisticated statistical techniques (i.e. Artificial Neural Network) to accurately describe the (non-)linear trends for all properties. In Phase III, we investigated the role of aromatics in improving certain properties of GTL jet fuels, such as density and elastomer compatibility (which is essential for fuel tank sealing). Analogous to the investigations conducted in Phase I, visualization models were developed to identify the optimum GTL jet fuel composition formulated by normal-, iso-, cyclic-paraffins and mono-aromatics. Currently, we are working on Phase IV which involves expanding our model to include new additives and component families in order to optimize the blending strategy for Qatar's GTL products and to increase their market value. The success in this direction could provide cheaper and more environmentally friendly synthetic jet fuels derived from natural gas, compared to the current oil-derived Jet A-1 fuels.

In addition to the technical results, our fuel characterization lab acts as a training ground for young and talented scientists in order to develop their technical and soft skills. Students get the opportunity to work in a professional environment with strict safety and quality regulations on par with industrial standards, to report scientific data and to draw conclusions from this information in order to make decisions on the next course of research activities.
Optimization of biofuel production using hydrocolloids from red and brown algae along Qatar coast
Authors: Piet Remi
Published: October 2012

The development of clean energies is a central challenge for the sustainable development of the Gulf region. Global pressures including climate change mitigation efforts and energy security concerns are calling for strong investments in alternative sources of energy.

Most of marine algae present in Qatar have no equivalents on earth and therefore could be considered as irreplaceable sources of primary and secondary metabolites. This is especially the case for hydrocolloids from red and brown algae that are cultured and used at an industrial scale for food-processing. This study analyzes the adaptability of existing biofuel production processes currently used for cooking oils or more traditional corn ethanol to algae fuel production.

The potential benefits of biofuel from photosynthetic algae could be significant. Algae can be grown using land and water unsuitable for crop plant or food production, unlike some other first and second generation biofuel feedstocks. Moreover, select species of algae produce bio-oils through the natural process of photosynthesis - requiring sunlight, water and carbon dioxide, supplemented with nutrients. Growing algae therefore consume carbon dioxide, which provides greenhouse gas mitigation benefits. Finally, bio-oil produced by photosynthetic algae and the resultant biofuel will have molecular structures that are similar to the petroleum and refined products we use today. This helps ensure the fuels are compatible with existing transportation technology and infrastructure. In conclusion, if successful, bio-oils from photosynthetic algae could be used to manufacture a full range of fuels including gasoline, diesel fuel and jet fuel that meet the same specifications as today's products.

This study bridges with a past survey carried out by Dr. Jean-Michel Kornprobst on the algae resources in Qatar and existing engineering processes currently developed in the United States and more specifically by the University of South Florida Polytechnic (Dr Philippidis) or the Abbess Ceter on Ecosystem Science and Policy at the University of Miami. Its objective is to assess the production capacity in Qatar as well as suggest projects and international cooperation to reach full potential.
Preliminary assessment of geochemistry and grain-size distribution of soils in Qatar
Authors: AlHajri Salma , Costa Ozeas
Published: October 2012

Soil plays an important role in life, especially in the cycling and supply of nutrients and water. Soil degradation is a serious global problem. It is caused by improper use of soil for different human activities. Soil degradation can lead to a significant decline in the productivity of agricultural lands. On a global scale, the annual loss of 75 billion tons of soil (mostly through desertification and soil erosion) costs the world about US$ 400 billion. Over 33% of the global land surface is affected by desertification, while only about 11% of global soil is considered to be stable. This study aims to perform a preliminary assessment of the soil quality at different locations in Qatar. Samples were collected from 14 sites at 8 different locations in the central east of Qatar, in May 2012. These locations are representative of a variety of desert soils (Umm Al-Zubar, Sealine, Semeisma, and Umm Al-Amad), farmland (Al Sailiya), a wastewater pond (Abu-Nakhala), a sandy beach (Katara Beach) and a protected area (Biological Field at Qatar University).

The samples were analyzed using a Master Sizer 2000 particle size analyzer for grain-size analysis and by using ICP-MS for geochemical analysis. The results showed significant difference in soil texture (grain-size analysis) between all the study sites. Grain-size distribution analysis showed that soils at the Abu-Nakhala wastewater pond and the Katara Beach are composed almost exclusively of coarse particles (sand-size or higher), while area 3 of the QU Biological Field contained the highest amount of fine particles (over 52% of silt and clay). Geochemical analysis of the soil samples indicate that calcium is the dominant fraction in most of the samples, with concentrations varying between 61% and 89%. Magnesium is the second most abundant element (with concentration varying between 3% and 26%), followed closely by aluminum, with concentrations between 3% and 15%. Potassium (concentrations between 1% and 8%) and iron (1% to 6%) complete the list of major elements in the studied soils.
Optimum power transmission-based droop control design for multi-terminal high voltage DC offshore wind farms
Authors: Abdel-kalik Ayman , Massoud Ahmed , Ahmed Shehab
Published: October 2012

Power generation through wind is expected to play a major role in the world's future energy portfolio. Wind power integration remains a challenging research area due to the unique characteristics of wind power generation. In particular, offshore wind has received significant attention worldwide due to the vast generation potential available. The electrical infrastructure of offshore wind farms is thus of significant importance. Multi-terminal high voltage direct current (HVDC) technology represents a preferable solution and has shown promise in solving wind farm interconnection problems. Droop control techniques have been proposed as a means to regulate the DC voltage and facilitate the automatic coordination between different converters without the need for fast communication between units. Different methodologies have been suggested to select the droop gains to satisfy the system performance specifications. In this work, a control design methodology is proposed for power sharing among the multi-terminal HVDC feeders providing that the power transmission efficiency is optimized. A simulation study on a 400 kV/1000 MW four-terminal HVDC transmission topology is conducted to determine the validity of the proposed methodology.
Simulation of a commercial-scale slurry bubble column reactor using cobalt catalysts
Authors: Morsi Badie , Sehabiague Laurent
Published: October 2012

A user-friendly simulator based on a comprehensive computer model for slurry bubble column reactor (SBCR) developed in our laboratory was used to predict the performance of a conceptual commercial-scale (9-m ID and 50-m height) SBCR for indirect coal conversion using Fischer-Tropsch (F-T) synthesis in the presence of a cobalt catalyst. New correlations for predicting the hydrodynamic and mass transfer parameters and three different kinetic rate expressions from the available literature specifically for cobalt catalysts were incorporated in the simulator. The effects of operating conditions, including catalyst concentration, pressure, temperature, H2/CO ratio, and superficial gas velocity on the SBCR performance were predicted using the simulator. The predictions showed that the performance of the SBCR was strongly dependent on the kinetic rate expression used. At low catalyst concentration, the reactor operated in a kinetic-controlled regime with increased syngas conversion and catalyst productivity; however, increasing catalyst concentration drove the reactor to operate in a mass transfer-controlled regime with decreased syngas conversion and catalyst productivity. The transition from kinetic-controlled regime to mass transfer-controlled regime occurred at different solid concentrations depending on the kinetic rate expressions employed. High H2/CO ratios in the inlet feed gas to the SBCR led to high syngas conversion. Increasing the superficial syngas velocity in the reactor decreased the gas residence time, which decreased the syngas conversions. High operating temperature always resulted in high syngas conversion. Also, the effect of operating pressure on the SBCR performance was not clear, since increasing pressure resulted in low or high syngas conversion depending on the catalyst and kinetic rate expressions used.
Outbursts and cavities in comets
Authors: Ipatov Sergei
Published: October 2012

In 2005 the impact module of the Deep Impact (DI) spacecraft collided with Comet 9P/Tempel 1. Based on analysis of the images made by this spacecraft during the first 13 minutes after the impact, Ipatov and A'Hearn concluded that the triggered outburst of small particles and excavation of a large cavity with dust and gas under pressure began at te= 8s, where te is the time after the DI collision. Schultz et al. analyzed images of Comet Tempel 1 made by the Stardust spacecraft and supposed that the diameter of the transient DI crater (dtc) was about 150-200m. Some authors support smaller values of dtc (up to 50m).

My recent studies were devoted to estimates of the distance between the upper border of the cavity (dcav) excavated at te= 8s and the pre-impact surface of the comet. In particular, I supposed that the depth of a growing crater is proportional to te^gamma (where gamma is about 0.25-0.4) during the intermediate stage of crater excavation.

The most probable estimate of dcav was about 0.1dtc*(te/Te)^0.3+1 meters, where Te is the duration of the normal ejection (Te=500 s at dtc=150 m). Using this approach I obtained dcav to be 5 or 6 meters for dtc equal to 150 or 200 m (dtc is 3 or 4 m for dtc ~ 50-100 m). The obtained values of the depth are in accordance with the depth (4-20 m) of the initial sublimation front of the CO ice in the models of the explosion of Comet 17P/Holmes considered by Kossacki and Szutowicz. The porous structure of comets provides enough space for sublimation and testifies in favor of existence of cavities. Natural outbursts were observed for several comets.

Our studies testify in favor of that cavities with dust and gas under pressure located a few meters below surfaces of comets can be common. Similarity of velocities of particles ejected at triggered and natural outbursts shows that these outbursts could be caused by similar internal processes in comets.
Optical and surface properties of anatase TiO2 by sol-gel for solar cells
Authors: Aljufairi Najat
Published: October 2012

Introduction:
Solar energy has been one of the most active research areas in the last decade because it is environmental friendly with respect to conventional energy resources. Titanium dioxide (TiO2) is a promising oxide material that has useful electrical and optical properties. It has been extensively investigated for photovoltaic applications. Anatase titania (TiO2) is a well known n-type inorganic metal oxide semiconductor, it is transparent to visible light and has a high refractive index. TiO2 thin films have successfully been used in preparation of solar energy cells. Sol-gel is widely used because of its simplicity, commercial viability, and potential for cost effective mass production. It is also used for industrial fabrication because of its low-cost availability.

Objectives:
The effects of substrate types and thickness on structural, morphological and optical properties of dip-coated TiO2 thin films for applicability usage in solar cells were studied.

Methods:
TiO2 films have been prepared by sol-gel dip coating technique, using titanium isopropoxide (TIP) as precursors. The structure and the phase of TiO2 films were analyzed by x-ray diffraction which showed that films were anatase. Optical properties of the films were characterized by ultraviolet-visible spectroscopy and ellipsometry.

Results:
The optical band gap was calculated for anatase film layers 50, 100, 150 and 200nm at 3.95, 3.87, 3.75 and 3.70eV, respectively. The refractive index of the films were computed by ellipsometry which were in the range of 1.9 to 2.3 and a wavelength range from 380 to 600nm. The thickness of the films was obtained from ellipsometry as of 58nm per one dip. The surfaces of TiO2 thin films were analyzed by a scanning electron microscope (SEM), atomic force microscope (AFM) and energy dispersive spectrometer (EDS). The images obtained by SEM showed cracks and shrinkage particles in the film, whereas the images obtained by AFM showed a homogeneous distribution of elongated shapes of nanoparticles through the film. In addition, the composition of TiO2 thin films checked via EDS found a small amount of Ti.

Conclusion:
The results showed that anatase titania (TiO2) nanomaterials have a promised potential for applications in solar cells.
Nilpotence in physics: Generalized uncertainty principles and Tsallis entropy
Authors: Kalogeropoulos Nikolaos
Published: October 2012

Background and Objectives:
The objective of this work is to illustrate concepts and applications of nilpotent structures in physics. To that end, we will use two examples, both of which have attracted considerable attention recently: the generalized uncertainty principle, in its various forms, and the Tsallis entropy. The former has been motivated and extensively used in string theory and black hole physics during the last two decades. There are almost 4000 papers written on the latter during the last 20 years, reflecting a considerable interest in Tsallis entropy as an alternative to the Boltzmann-Gibbs-Shannon (BGS) entropic form. The Tsallis entropy has been having a considerable impact in re-examining the foundations of statistical mechanics for both equilibrium and non-equilibrium processes.

Nilpotent structures have a long presence in various branches of mathematics, especially in group theory and geometry with the works of Malcev and Gromov standing out as particularly pertinent for our purposes. We also consider the sub-Riemannian aspects of nilpotent structures which have applications in a variety of fields ranging from examining how a cat falls to analyzing human vision.

Results:
Both the generalized uncertainty principles and the Tsallis entropy indicate that the dynamical structure of spacetime and the statistical methods used to quantize it may benefit considerably if one uses general nilpotent structures instead of the two-stage Heisenberg model or the abelian group of the BGS entropy.

Conclusions:
Nilpotent structures are flexible enough to generalize aspects of quantum theory and statistical mechanics. At the same time, they are understood well enough to allow us to obtain results of potential physical significance. Hence they are worth taking a look at and exploring their consequences.

Notes:
Partial results have already been published by the author recently and have appeared in the arXiv.org repository and are being presented at various international conferences. Parts of this work were done in collaboration with A. J. Creaco of the City University of New York.
Identification of source of oil spills in the environment using biomarkers and isotopes
Authors: Dessort Daniel , Hassan Hend
Published: October 2012

Today, the use of standard tools of petroleum organic geochemistry is the most convenient way to characterize and quantify contamination of environment by fossil fuel. Good knowledge of natural processes that alter the hydrocarbons during biodegradation, weathering, oxidation or simply evaporation, can also be applied to predict the fate of a pollution.

For instance, organic geochemistry played an important role in the environmental assessments of oil spills (e.g.Exxon Waldez or Deep Water Horizon).

Oil spill identification is usually conducted by a specialized laboratory in order to find the source of a spill. Guidelines on recommended methods for sample collection, handling and analysis are well established (e.g. NORDTEST Oil Spill Identification system).

At TRCQ, we use a variety of geochemical techniques in order to:

*make the distinction between naturally occurring hydrocarbons and anthropogenic pollution;
*make the distinction between crude oil and refined hydrocarbons;
*assess the origin of oil spills, oil slicks and gas seeps--these techniques can be used for the characterization of the origin of fluids in the case of well integrity issues;
*monitor the fate of spilled oil and its alteration;
*map the spatial distribution of hydrocarbon pollutants in sediments and aquifers and their evolution through time.

Advanced geochemical techniques are used:

*high resolution gas chromatography (HRGC) for fingerprinting;
*HRGC coupled with mass spectrometry (HRGC/MS) for fossil biomarkers analysis;
*compound specific isotope analysis (CSIA), a sophisticated technique that consists of measuring the carbon and hydrogen stable isotope ratios of individual compounds (C1 to C30) separated by GC; the stable isotope ratio of individual components depends on their source and their alteration, and CSIA is the only technique able to correlate the gas seep to its source.

In this paper, we show the use of organic geochemistry to characterize the oil spill pollution at seabed occurring in 1998. GC-MS analyses of the alkane fractions has allowed delineating three groups of samples:

*samples dominated by a petroleum signature;
*samples in which petroleum occurs with a subordinate land-derived contribution;
*samples in which petroleum is associated to a recent marine input--within this group one may generate a subgroup in which some terrestrial debris have been seen in minor amount.
HAWA'AK: An end-to-end air quality monitoring system for Qatar
Authors: Yaacoub Elias , Kadri Abdullah , Abu-Dayya Adnan
Published: October 2012

The effect of air pollution on human health is considered a major and serious problem, globally. The purpose of air quality monitoring is not merely to collect data but to provide the information required by scientists, policy-makers and planners to enable them to make informed decisions on managing and improving the environment, as well as to present useful information for public end-users. Monitoring fulfills a central role in this process, providing the necessary, sound scientific basis for developing policies and strategies, setting objectives, assessing compliance with targets and planning enforcement action.

Traditionally, bulky air quality monitoring stations are used for collecting various gas concentrations. These stations include many reference analyzers. Although they have a high level of accuracy, such stations require frequent calibration and maintenance and they need access to power sockets mainly for air conditioning, which limits their use on a large scale. Research and industrial bodies are focusing on developing a new generation of sensing stations at a low cost, smaller size, and with more mobility features. Variations of such stations are being used in different indoor and outdoor environments for both residential and industrial applications.

These sensor stations are generally deployed as a wireless sensor network (WSN). A WSN is composed of a number of sensing stations transmitting wirelessly the information they capture. A sensing station is generally composed of a power unit, processing unit, sensing unit, and communication unit.

In this work, a real-time air quality monitoring system is presented. This system is based on utilizing multi-gas (MG) monitoring stations that communicate with a platform by means of machine-to-machine communication. Each MG monitoring station includes gaseous sensing elements, a data logging component, and a wireless communication board. They are powered by solar energy. The platform is located on a backend server where data cleaning and filtering operations are carried out.

In addition, this platform converts the received data to useful information that is delivered to users through web portal and mobile applications. The system uses a high density of sensing stations per unit area in order to provide localized pollution information, as opposed to bulky analyzers deployed in limited numbers.
Effect of salinity on carbon and sulfur cycles in Umm Alhool sabkha microbial mat ecosystem in Qatar
Authors: Al-Najjar Mohammad , Al-Thani Roda , Al Raei Abdul Monem
Published: October 2012

Microbial mats are only present under extreme conditions, where grazing by higher organisms is limited. Therefore, microbial mats may provide insight into extraterrestrial life, due to their adaptations to extreme temperatures, desiccation or salinity. They are faced with a diurnal cycle with variable length based on their location, which exposes them to extreme salinity conditions (i.e., water withdrawal and high evaporation). Cyanobacteria in the photic zone of a mat ecosystem supply the other microorganism with the required organic material to produce energy and grow. Subsequently, this will reproduce the nutrients needed by the phototrophs through elemental re-mineralization.
In this work, we investigated the effect of water salinity that covers the microbial mat ecosystem of Umm Alhool sabkha, Qatar, regarding the most important processes within microbial mats: photosynthesis and sulfate reduction (SR). Our results showed that both photosynthetic and sulfate reduction rates decreased with increasing the salinity. The microbial community structure, assessed by 454 pyro-sequencing, revealed that the cyanobacterial community structure changed in response to the change in salinity. This was not the case for the sulfate reducer community structure, which stayed as it is in the mats incubated at different salinities. Therefore, we speculate that salinity affects the photosynthetic community structure, and consequently affects the photosynthetic activity of the whole ecosystem. However, sulfate reduction rates decreased due to less organic material supply from the upper layers and not due to change in microbial community structure of SR. Other factors such as the activity of the enzymes could also have an effect on SRR, but it was not investigated in this study.
Application of chemically synthesized polyaniline-polystyrene blend as a carbon dioxide gas sensor
Authors: Bhadra Jolly , Al-Thani Noora , Madi Nabil K , Al-Maadeed Mariam A.
Published: October 2012

The use of conducting polymers as sensing elements in chemical sensors is attracting attention due to their high sensitivity in change of the electrical and optical properties when exposed to different types of gases or liquids. The ease in synthesis of these polymers and sensitivity at room temperature add to the sensors' advantages. This can be of importance particularly considering CO2 sensors that are used in different applications such as industrial process, fertilizers, and environmental pollution monitoring. Polyaniline (PANI) is one of the most attractive materials among the variety of conducting polymers due to its unique electrical properties, environmental stability, easy fabrication process, and intrinsic redox reaction.
In our present work we successfully prepare conducting polymer PANI-polystyrene (PS) blends doped with HCl by an in situ dispersion polymerisation method. Keeping the aniline concentration constant, five blends are prepared using different monomer ratios of PS. The PANI-PS sensors are deposited on glass substrates by the dripping method. The obtained sensors are characterized by SEM for morphology study and electrical properties by IV characteristics and four-probe conductivity study.
The electrical conductivity of the composite films ranged from 4.3 x10¯5 - 5.2 x10¯² S·m¯¹. There is an increase in conductivity value with the decrease in PS content. This is justified as there is an increase in the number of more conducting species, i.e., PANI in the composite with a lower PS content. The PANI-PS blend sensors show good sensitivity to CO2 gas. In particular, sensors with higher concentrations (above the percolation threshold) of PANI, displayed excellent sensitivity and fast response.
Conducting polymer PANI-PS blends are prepared using five different concentrations of PS (i.e., 1 M, 0.9 M, 0.8 M, 0.7 M and 0.6 M), and the films obtained are characterized using SEM. SEM pictures show nanoparticle formation, and as the PS concentration decreases, particles combine to form clusters or chains. The electrical properties are also observed to increase with a decrease in the PS concentration. The I-V characteristics show some non-ohmic behavior. The CO2-sensing behavior is most responsive for the blends containing 0.7 and 0.6 M of PS.
The possibility to lower building energy consumptions in Qatar
Authors: Kharseh Mohamad , Hassani Ferri , Al Khawajah Mohammed
Published: October 2012

Most global energy comes from fossil fuel. Currently, there is a strong belief that climate change is anthropogenic and attributed to fossil fuel consumption. Heating and cooling systems account for half of global energy consumptions. In hot and underdeveloped countries such as Qatar, the share of air conditioning systems is expected to be even more than half the national energy consumption. This provides the challenge to study energy consumption in building sectors to find new methods to increase the performance of air conditioning systems. Up until now, renewable energy sources supply only around 2-3% of the annual global heating and cooling demand. Due to its high thermal performance, heat pump systems and in particular ground coupled heat pump systems (GCHP), are increasingly becoming more common for air conditioning applications. In the light of the improvement in performance of photovoltaic systems, the combination between the photovoltaic and HP or GCHP is gaining more economic feasibility.

This paper studies renewable energy options for building cooling systems for energy and environment savings. To achieve this goal, a residential apartment in Doha, Qatar, was selected as a case study. The cooling demand of the case study was assessed and four different cooling systems were designed including: (1) air coupled heat pump system (as a reference system); (2) ground coupled heat pump; (3) air coupled heat pump combined with a photovoltaic panel to generate electricity; and (4) ground coupled heat pump combined with a photovoltaic panel to generate electricity. Compared to the reference system, the reduction in the non-renewable energy consumption and the payback time was estimated for each system.
What's up with Qatar? How eustasy and neotectonics influenced the late Pleistocene and Holocene sea-level history of Qatar
Authors: Jameson Jeremy , Strohmenger Christian
Published: October 2012

The evolution of coastal plains, the present day shape, and surface hydrology of Qatar are related to changes in relative sea level. Several factors acting on different time scales have contributed to sea level changes. These include tectonism and glacioeustasy. The peninsula shape is the surface expression of the Qatar Arch, one of the largest structural features of the Arabian Plate. It plunges northward into the Zagros foredeep. The Arabian Gulf initially formed during the Tertiary period as a foreland basin due to the uplift of the Zagros Mountains.

Previous studies indicate the Arabian Gulf was an arid fluvial plain during the Last Glacial Maximum, 18,000 years before present (BP). The Gulf floor was a likely route for people migrating between Iran and Arabia. 14,000 years BP the sea level started rising, flooding the Gulf. The period between 14,000-7000 years BP was marked by a rapid rise (1 m/100 yr) driven by the melting of the polar ice caps. Age dating of Qatar coastal deposits indicate the rate of rise decreased as the sea level approached present day, 7000 years BP. Most coastal deposits are relicts of a Holocene sea-level highstand, dating from 7000-3000 years BP. Holocene beaches at 2-4 meter elevations and up to 15 km inland are relicts of this highstand. Similar beaches are found elsewhere along the Gulf. During this period coral reefs formed a discontinuous fringe around the windward and oblique Qatar coastlines. A drop of sea level approximately 2000 years BP may account for the demise of the fringing reefs.

The occurrence of Late Pleistocene to Miocene fluvial gravel deposits of the Hofuf Formation 20 to 40 meters above sea level are interpreted as being related to long-term tectonic uplift, the evolution of the Zagros foredeep and structural tilting of the Arabian plate. Pleistocene shoreline deposits above present sea level dating from 30,000-40,000 years BP are interpreted as part of the same structural flexural event.

Thus, data from Pleistocene to present suggest that the sea-level history of Qatar reflects relatively high frequency changes driven by eustasy superimposed on a long-term pattern of tectonic uplift.
Behavior of porous materials under asymmetric dynamic loading
Authors: Bugarin Sinisa , Paskaramoorthy Ratnam
Published: October 2012

Background and Objectives:
Stress concentration around cavities and cracks strongly influence the fracture and fatigue properties of porous materials. Microcracks that form around discontinuities in the material such as cavities link up to form macrocracks leading to substantial degradation of material mechanical properties. The dominant factor aiding the formation of microcracks is the stress concentration. The study investigates the dynamic stress concentration around different size oblate spheroidal cavities due to shear waves in an infinite elastic medium.

Methods:
As the available analytical methods are only applicable to simple shape cavities, hybrid methods have been presented to study the stress concentration around different shape cavities embedded in an elastic medium. The method used combines the finite element method with analytical procedure for elastic wave propagation in an elastic medium. The accuracy of the method was verified by analyzing a spherical cavity.

Results:
Different shape oblate cavities are investigated under varying frequencies of shear waves and different matrix material properties. The stress concentrations within the matrix are found to be dependent on the frequency of incident shear wave, aspect ratio of the cavity and the Poisson's ratio of the matrix.

Conclusions:
The study reveals that the dynamic stress concentration can reach much higher values than the static case. Dynamic stress concentration factors as high as 6 result for low aspect ratio cavities of 0.2 and even values of 6.6 with a materials Poisson's ratio of 0.45.
Nanofluids: Optical properties and its effects in near-wall measurements
Authors: Sadr Reza , Kanjirakat Anoop
Published: October 2012

Engineered colloidal suspensions of nano-sized particles in base fluids (nanofluids) have shown promise in heat transfer research as a potential for future heat transfer fluid. However, the conflicting reports on the thermal properties of these fluids necessitate a detailed look into the physical mechanisms behind this enhancement. As heat transfer is a surface phenomenon, near-wall fluid flow and temperature measurements could provide considerable insight in this regard. Optical methods are commonly used to probe the flow at micro/nano scales. As the accuracy of these measurement techniques depend on knowledge of the optical properties of the fluid under consideration, a detailed understanding of these properties is required. For example, evanescent wave-based nanoparticle image velocimetry (nPIV) can be an effective tool in exploring near-wall nanofluid velocity/temperature field. In this method, an evanescent wave illumination is used to measure near-wall velocity fields with an out-of-plane resolution of the order of O(100 nm). In this study, optical properties of SiO2-water nanofluids at various particle concentrations varying from 0 to 6% by weight are investigated. Measurements of refractive indices and the optical transmittance of nanofluids, which are directly related to the depth of penetration in nPIV measurements are carried out. The effect and the correction required in the nPIV measurements due to the modification in optical properties of nanofluids are discussed. The results obtained demonstrate that addition of nanoparticles exhibit a change in optical properties that could affect optical-based measurement in nanofluids.
Understanding the link between moisture dynamics and microbial activity in mobile dunes
Authors: Abdul Majid Sara , Louge Michel , Hay Anthony , Richer Renee
Published: October 2012

Barchan dunes in southeastern Qatar are relentlessly pushed by northwesterly, shamal, winds. This research aims to understand whether a synergy between moisture retention and microbial growth could be exploited to stop them from upsetting natural habitat as they pass. These mobile dunes in Qatar also constitute a unique test area in which to study mechanisms of desertification.

After characterizing the behavior and shape of the dune field west of Umm Said, we developed unique instruments for detecting humidity in hyper-arid environments. Using those, we measured diurnal variations in temperature and humidity beneath the dune, as well as fluxes of carbon dioxide through the surface. We also recorded temperature and humidity from a probe initially buried on the dune's avalanche face, emerging 15 months later on its windward face. In the laboratory, we measured effective diffusion, permeability and activity of its sands. By inserting an artificial rippled porous surface in our wind tunnel, we recorded how winds can induce a flow of air within porous sands, thus facilitating moisture and dust intake.

Metagenomic analysis of DNA extracted from two dunes revealed that the dune microbial communities were dominated by bacteria from the actinobacteria and firmicutes phyla. Consistent with the known metabolic capacity of these phyla, in silico assessment of the metabolic potential of the dune microbial community suggests that is dominated by heterotrophic bacteria, with surprising few genes for photosynthesis being detected. Other genes, however, were detected that may prove useful in dune stabilization efforts such as urease, and in biotechnology applications such as antibiotic biosynthesis. We succeeded in adapting cultivation independent methods for quantifying viable microbes directly from the sand and in culturing microbes found on individual sand grains. Analysis of the metabolic potential of these isolates is ongoing.
Heat wave hazard modelling in Qatar
Authors: El Morjani Zine El Abidine , Mohieldeen Yasir Elginaid , Mohamed Ahmed Abdulla , Al-Sulaiti Mohammad Hassan
Published: October 2012

Background & Objectives:
Heat wave hazard modelling is attracting a lot of attention, especially with the onset of climate change and global warming currently taking place. General global climatic models and trends predict that heat waves will increase in frequency, duration, and intensity. Yet, heat wave hazard modelling remains a challenging and imperative problem because of the complexity introduced by natural and human elements such as land-use, air temperature variability, topography, soils characteristics, and air pollution. In this study, heat wave hazard in Qatar is mapped, modelled and predicted for two and five years.

Methods:
Geographic information system (GIS) and remote sensing (RS) techniques are used to carry out multilayer analysis by combining different parameters that influence and determine heat wave in the region. Land surface temperature (LST) derived from remotely sensed data (Landsat ETM thermal infra-red band) is also used in the analysis. The LST image proved to be extremely useful as the variation of the thermal phenomenon is highly related to and reflects the land surface variability in the study area. Heat wave index (HWI) is calculated using in situ and Gumbel frequency analysis is used for head wave (HW) prediction. Step-wise regression analysis is used to identify the predictive variables/parameters of HWI and to determine the model.

Results:
The magnitude and spatial distribution of heat wave in Qatar are mapped. These results can be used address environmental, health, and urban planning issues.
Population-census data is used to estimate the proportion of the vulnerable age groups that will be affected by HW in Qatar. More than 87% of children aged 4 and less are found to be at very high risk to HW, while more than 86% of people above 65 years are at the same level of risk.

Conclusions:
GIS and RS techniques are valuable research tools for environmental studies. The model developed here can be used by decision makers and planners to make better informed decisions on planning of hospitals and schools in low heat wave risk areas. Furthermore, the model gives a good indication for planning future electric energy consumption by air-conditioning and cooling of buildings.
Analysis of CO2 equilibrium data in aqueous solutions of DEA, MDEA and their mixtures using the modified Kent Eisenberg model and the Deshmukh-Mather model
Authors: Benamor Abdelbaki , Aroussi Abdelwahab
Published: October 2012

Alkanolamine solutions are widely used for the removal of acid gases such as CO2 and H2S from process streams containing these components in the industries. The technique has been proven to be reliable and has found wide application in many chemical industries such as ammonia production, coal gasification and natural gas processing. In this work, equilibrium data of CO2 absorption in aqueous solutions of single and mixed amine was analysed using the Modified Kent Eisenberg model and the Deshmukh-Mather model. Experimental data on CO2 loading in aqueous solutions of DEA and MDEA at temperatures ranging from 303K to 323K and CO2 partial pressure from 0.09kPa to 100 kPa obtained using a stirred cell reactor was fitted to generate the different parameters required in each model. Using the generated parameters, the models were applied to predict the CO2 loading in solutions of DEA and MDEA reported in the literature. In all cases, it was found that both models were found to give a good prediction of CO2 loading over a wide range of operating conditions. However, the Deshmukh-Mather model was found to be more accurate compared to the Kent Eisenberg model in predicting CO2 loading, especially at low CO2 partial pressures.