Pyrene bisiminopyridine ligand and its zinc complex

The synthesis of a pyrene bisiminopyridine ligand L was successfully accomplished by condensation between 1-aminopyrene and 2,6-pyridinecarboxaldehyde. The complexation of L with zinc triflate afforded a neutral metal complex formulated as [Zn(H2O)LCF3SO3)2].2Et2O. In the complex, the ligand is coordinated to zinc(II) through its three nitrogen atoms which form a distorted octahedral environment together with three oxygen atoms, two from the triflate anions and one from aqua ligand. Both compounds have been characterized using NMR, elemental analysis, mass spectrometry, electronic absorption (UV-Vis) and infrared. Luminescence properties of these compounds show an emission maxima at 412 nm, indicating a pyrene monomer emission

Specific heat and magnetocaloric effect in Pr1-xAgxMnO3 manganites

The magnetocaloric effect in alternating magnetic fields has been investigated in Pr1-xAgxMnO3 manganites with x=0.05-0.25. The stepwise reversal of the sign of the magnetocaloric effect has been revealed in a weakly doped sample (x=0.05) at low temperatures (~80 K). This reversal is attributed to the coexistence of the ferromagnetic and canted antiferromagnetic phases with different critical temperatures.Comment: 4 pages, 4 figure

Metal Complexes of a Pyrene based iminopyridine ligand: Synthesis, X-ray structures and Optical properties

National audienc

Chemical Characterization and Source Identification of Beached Oil from Two Areas Along the North-Western Coast of Qatar

Over the years there have been several reports of oil spills affecting particularly the northern coast of Qatar. In most cases, the source of oil spills is not identified. The spilled oils are very resistant to degradation and can affect the coastal ecosystem over many years. Even today, after 24 years, some of the oil that was spilled during the 1991 Gulf War can be found in sand, close to the Al Zubahra UNESCO site. The Maersk Oil Research and Technology Center in Doha (MO-RTC) has established the Oil Fingerprint project in collaboration with the University of Qatar and the University of Copenhagen. One of the objectives of the collaboration is to identify the potential source and origin of oil spills based on their chemical composition. A total of 38 samples were collected. During the sampling campaign it was discovered that the coast was contaminated with highly weathered oil that could originate from the Gulf War era but also with more fresh oil that most likely originates from recent oil spills in the Arabian Gulf. We therefore collected polluted soil samples and contaminated sediments from two main areas along the beach in North-western Qatar. The samples were analysed using gas chromatography - mass spectrometry in selected ion monitoring mode (GC-MS/SIM) and the oil composition was characterized. The likely source of the beached oil was identified by a comparison of diagnostic source ratios by comparing petroleum hydrocarbon fingerprints of steranes and hopanes of the spills against an oil database. The initial chemical fingerprinting based on selected ion chromatograms (SICs) of steranes (m/z 217) and hopanes (m/z 191), were remarkable similar as were the C29-/C30-Hopane ratios between sampling sites. However, a more detailed pixel-based analysis showed significant differences between samples. The process also included an assessment of the physical and biological weathering effects on the oil spills. Petroleum biomarker patterns (steranes and hopanes) are identical for all 14 samples included in this pilot study. The only differences observed were in the relative concentration of LMW and HMW steranes. This could be due to real source oil differences, however, the general weathering patterns indicate that these differences are more likely due to extensive weathering of especially two samples (9-02, 3-02) but also 8-01 and 10-01 shows severe weathering effects. Analysis of alkyl-PAHs provided an overall evaporative weathering degree for the samples. Distinct differences in the isomer patterns were observed for 3- to 4-ring alkyl-PAHs and this cannot be immediately explained as biodegradation. The largest fraction of the samples seems to originate from the same source but other sources are clearly present. A more detailed analysis with normalization to Euclidean norms within six selected SICs revealed more source specific information. In conclusion, the results indicate at least 2-3 different sources on the basis of differences in PAH isomer patterns. This was confirmed by visual inspection of SICs of C1-C3 alkyl-substituted phenanthrene, dibenzothophene, chrysene and pyrene isomers. Apart from the finding that the spills originate from several sources, the evaporation profiles indicated that not all of the spills are crude oils but that some are also heavy fuels. This suggests ongoing bunker flush off the coast of Qatar. These findings are of importance in further bioremediation processes in which, different approaches should be investigated to achieve high efficiency strategies if removal of oil pollutants from AlZubaraa area.qscienc

Proteomic analysis of T. qataranse exposed to lead (Pb) stress reveal new proteins with potential roles in Pb tolerance and detoxification mechanism

Soil lead (Pb) contamination is one of the environmental problems facing the modern world. Sources of Pb in soil include industrial activities such as mining and smelting processes, agricultural activities such as application of insecticide and municipal sewage sludges, and urban activities such as use of lead in gasoline, paints, and other materials. Phytoremediation is the direct use of living green plants and is an effective, cheap, non-invasive, and environmentally friendly technique used to transfer or stabilize all the toxic metals and environmental pollutants in polluted soil or groundwater. Current work in this area is invested in elucidating mechanisms that underpin toxic-metal tolerance and detoxification mechanisms. The present study aims to gain insight into the mechanisms of Pb tolerance in T. qataranse by comparative proteomics. MALDI-TOF/MS and in silico proteome analysis showed differential protein expression between treated (50 mg kg⎯1 Pb) and untreated (0 mg kg⎯1 Pb) T. qataranse. A total of eighty-six (86) differentially expressed proteins, most of which function in ion and protein binding, antioxidant activity, transport, and abiotic response stress, were identified. In addition, essential stress-regulating metabolic pathways, including glutathione metabolism, cellular response to stress, and regulation of HSF1-mediated heat shock response, were also enriched. Also, at 52- and 49-kDa MW band areas, up to six hypothetical proteins with unknown functions were identified. Of these, protein AXX17_AT2G26660 is highly rich in glycine amino acid residues (up to 76%), suggesting that it is a probable glycine-rich protein (GRP) member. Although GRPs are known to be involved in plant defense against abiotic stress, including salinity and drought, there is no report on their role on Pb tolerance and or detoxification in plants. Further enrichment analysis in the current study reveals that the hypothetical proteins do not interact with known proteins and are not part of any enriched pathway. However, additional research is needed to functionally validate the role of the identified proteins in Pb detoxification mechanism.Qatar University’s student grant QUST-CAS-SPR-2017-33 supports this study

Reuse of Sludge as Organic Soil Amendment: Insights into the Current Situation and Potential Challenges

Sludge generation as an organic by-product of wastewater treatment has seen a consistent increase worldwide due to population growth and industrial activities. This poses a chronic challenge regarding management options and environmental concerns. The agricultural valorization of unconventional organic materials has become inevitable, especially in semi-arid and arid countries that suffer from depleted soils and shortages in farm manure supply. High-income countries have also been interested in this recycling practice to mitigate landfilling or incineration issues. Sewage and some industrial sludges contain a complex mixture of beneficial and harmful substances, which varies with the origin of effluents. Therefore, sludge land application should be well managed in order to achieve sustainable agro-environmental goals. This review paper focuses on different aspects related to sludge reuse in agriculture, starting by investigating the diversity of sludge types and composition. In addition to the preponderant urban sewage sludge, the less-studied industrial sludges, such as those generated from pulp and paper mills or gas-to-liquid industries, are hereby addressed as well. Then, post-land application effects are discussed in relation to sludge quality, dose, and reuse conditions. The present paper also examines the disparities between guidelines that determine sludge conformity for land application in various countries or regions. Accordingly, special attention is given to increasing risks related to emerging pollutants in sludge such as pharmaceuticals, which have been overused since the outbreak of COVID-19 pandemic. This exhaustive investigation will assist the establishment of sustainable strategies for the safe agricultural reuse of biosolids.This review paper is an outcome of the research project M-QJRC-2020-9 funded in the framework of collaboration between Qatar University and Marubeni Corporation.Scopu

Use of environmental isotopes to assess the sustainability of intensively exploited aquifer systems (2012‐2015)

Intensive exploitation of groundwater over longer period has led, in many important aquifers, to marked lowering of water tables, increasing exploitation costs, and often, to a progressive deterioration of water quality. Concentrated pumping may also alter flow patterns permanently with the risk of migration of pollutants into aquifers from the surrounding aquifers or surface water bodies due to lack of physical protection to prevent them. Isotope hydrology tools have proven to be very useful in assessing groundwater hydrology, addressing aspects related to recharge processes, delineation of flow patterns, water quality issues and interactions with other water bodies; this unique information can be further used to evaluate long term aquifer sustainability. The objective of the Coordinated Research Project F33019 is to develop and review approaches and methodologies, mostly based on the combined use of conventional hydrogeological techniques and environmental isotopes, to assess the response of groundwater systems to intensive exploitation and groundwater availability. Access to new dating tools and approaches for groundwater dating covering different time scales offers the possibility to evaluate changes in groundwater dynamics and flow patterns, providing key data to predict the evolution of aquifers and their sustainability as major sources of water. The CRP aims to assess the performance of these new tools and approaches and the possible adoption of these methods by water management experts

The Healing Process of Intracorporeally and In Situ Devitalized Distal Femur by Microwave in a Dog Model and Its Mechanical Properties In Vitro

Background: Limb-salvage surgery has been well recognized as a standard treatment and alternative to amputation for patients with malignant bone tumors. Various limb-sparing techniques have been developed including tumor prosthesis, allograft, autograft and graft-prosthesis composite. However, each of these methods has short- and long-term disadvantages such as nonunion, mechanical failures and poor limb function. The technique of intracorporeal devitalization of tumor-bearing bone segment in situ by microwave-induced hyperthermia after separating it from surrounding normal tissues with a safe margin is a promising limb-salvage method, which may avoid some shortcomings encountered by the above-mentioned conventional techniques. The purpose of this study is to assess the healing process and revitalization potential of the devitalized bone segment by this method in a dog model. In addition, the immediate effect of microwave on the biomechanical properties of bone tissue was also explored in an in vitro experiment. Methods: We applied the microwave-induced hyperthermia to devitalize the distal femurs of dogs in situ. Using a monopole microwave antenna, we could produce a necrotic bone of nearly 20 mm in length in distal femur. Radiography, bone scintigraphy, microangiography, histology and functional evaluation were performed at 2 weeks and 1, 2, 3, 6, 9 and 12 months postoperatively to assess the healing process. In a biomechanical study, two kinds of bone specimens, 3 and 6 cm in length, were used for compression and three-point bending test respectively immediately after extracorporeall