Studies of Reaction Mechanisms in Organic Chemistry Using Radiochemical Techniques

An investigation of the mechanism of dehydrogenation of a hydroaromatic compound, 1:4,dihydronaphthalene, by a quinone, tetrachloro-1:4,benzoquinone, has been made. The reaction has been studied by kinetic measurements, spectroscopic measurements and by the determination of tritium isotope effects. The measurements were carried out at 80 C and phenetole was used as the solvent for the reaction mixture. In previous work in these types of systems second order kinetics are generally observed and the bulk of the experimental evidence suggests that the reaction proceeds by an ionic rather than a free radical mechanism. Transfer of a hydride ion has been postulated as the rate determining step. The present work does not entirely support this viewpoint; second order kinetics were only observed in the later stages of the reaction and in the initial reaction period the kinetic data suggest the mechanism is more complex than has previously been supposed. In addition, during the time over which the reaction was normally followed, i. e. 120 minutes, the amount of naphthalene formed is equivalent to approximately half of the 1:4,dihydronaphthalene consumed. The isotope effect measurements, using partially tritiated 1.4,dihydronaphthalene, have given a value of kT/k. =1.16+/-0.16. This result does not support the view that fission of the carbon-hydrogen bond is the rate-determining step, i. e. hydride ion transfer. The result is interpreted in terms of the first step in the reaction being the establishment of an equilibrium involving the formation of a charge-transfer complex and the value of k T/k greater than unity results from an inverse secondary isotope effect. The spectroscopic measurements prove the existence of charge-transfer complexes in the reaction mixture and indicate that the formation of these complexes is the initial step in the reaction. The extra consumption of 1:4,dihydronaphthalene in the reaction is ascribed to the formation of a chloro-substituted quinone in which a chlorine is replaced by monohydronaphthalene group. This byreaction would lead to the production of hydrogen chloride and the latter has been detected among the reaction products. It has been observed that significant amounts of hydrogen chloride do have a small catalytic effect on the reaction. The present work suggests that the reaction proceeds by an ionic mechanism but modifications in the earlier schemes are required. The following scheme is suggested for the reaction of the hydroaromatic compound (RH2) with the tetrachloroquinone (QCL4): RH2 + QCL4 ↔ charge-transfer complex (1) CT complex → RH+ + QCL4H- (2) RH+ + QCL4H-→ R + QCL4H2 (3) or CT complex → RHQCL3 + HCl (4) In systems where the quinone has a low redox potential, or where there is substantial steric hindrance, the formation of the charge transfer complex, step (1), can be rate determining, while with quinones of high redox potential step (1) is relatively rapid and step (2) is the rate determining step

An experimental and numerical study of water jet cleaning process

In this paper, we have experimentally, numerically and theoretically investigated the water jet cleaning process. Very high speed water jets (~80-200 m/s) are typically used in such cleaning operations. These jets diffuse in the surrounding atmosphere by the process of air entrainment and this contributes to the spreading of the jet and subsequent decay of pressure. Estimation of this pressure decay and subsequent placement of the cleaning object is of paramount importance in manufacturing and material processing industries. Also, the pressure distribution on the cleaning surface needs to be assessed in order to understand and optimize the material removal process. In an industrial setting, experimental study is performed to formulate the pressure characteristics. It has shown that the decay of stagnation pressure along the axial direction is linear. It also revealed that no cleaning is possible at radial locations greater than 1.68D from the centerline. Numerical simulations are performed to capture the process of air entrainment in the jet and the subsequent pressure characteristics. The simulation results are found to correctly predict the experimental data. Moreover, a theoretical model for evaluating the optimal and critical stand-off distances has also been derived. Based on our results, we found that the optimal stand-off distance in cleaning operations is ~5D and the jet looses its cleaning ability at axial distances greater than ~26D.Comment: This paper has been Accepted in the Journal of Materials Processing Technolog

Evaluation of plasma neurotransmitters in children living with Attention-Deficit Hyperactivity Disorder (ADHD)

This study aimed to ascertain the underlying neuro-biochemical imbalances that exist in children with ADHD by assessing the plasma levels of dopamine, serotonin, norepinephrine, γ aminobutyric acid (GABA) and glutamate. Moreover, it investigated the potential effects of PUFA and vitamins supplementation as an alternative therapy to modulate the levels of these neurotransmitters and the overall clinical status of ADHD patients. The study included 40 ADHD patients, aged 4-6 years. The diagnostic and statistical manual of mental disorders (DSM-5) test has been employed to diagnose patients with ADHD and the severity of symptoms was assessed using the Arabic version of Conners' Parent Rating Scale. Additionally, patients were assessed using the Arabic versions of Mini International Neuropsychiatric Interview for Children (M.I.N.I. Kid) and Stanford-Binet Intelligence Scale, 5th Edition (SB5). Recruited patient received nutritional supplement of semi-solid diet containing 1000 mg PUFA with selected vitamins once daily for six months. The evaluation of ADHD symptoms and levels of neurotransmitters has been carried out at pre-/post-intervention stage. Post-nutrition intervention assessment, there was a significant increase in dopamine, norepinephrine, GABA levels (p-value < 0.0001) with significant decrease in glutamate level (p-value < 0.0001) when compared to their correspondent pre-intervention levels. Symptoms of inattention and/or hyperactivity-impulsivity were significantly improved after 6 months nutrition intervention program (p-value<0.001). Therefore, supplementation with omega-3 fatty acids and vitamins could be considered more extensively in therapy of ADHD patients particularly those who are less than 6 years old

Impact of Perceived Organizational Support as Intermediary Variable between the Values of Organizational Confidence and Organizational Citizenship Behavior: An Empirical Study on the Staff of Al-Aqsa University in Gaza

هدفت الدراسة الحالية التعرف إلى أثر الدعم التنظيمي المدرك كمتغير وسيط على قيم الثقة التنظيمية وسلوك المواطنة التنظيمية بأبعادها الخمسة في جامعة الأقصى وهي (الإيثار – اللطف والكياسة – الروح الرياضية – السلوك الحضاري – وعي الضمير). ولتحقيق أهداف الدراسة قام الباحث بتصميم استبانة مكونة من (33) فقرة للحصول على البيانات، حيث قام بتطبيقها على عينة من العاملين في الجامعة بلغ عددهم (149) مبحوثاً. وقد اعتمد الباحث على المنهج الوصفي. وبعد التحليل الإحصائي للبيانات توصلت الدراسة إلى أن مستوى تصورات العاملين في جامعة الأقصى لقيم الثقة التنظيمية السائدة جاءت بدرجة متوسطة. ودرجة ممارسة العاملين لسلوك المواطنة التنظيمية جاء بدرجة متوسطة. أما مستوى إدراكهم للدعم التنظيمي جاء بدرجة مرتفعة. كما أشارت النتائج إلى أن الدعم التنظيمي المدرك يتوسط بشكل كلي العلاقة ما بين قيم الثقة التنظيمية وسلوك المواطنة التنظيمية في بعدي (الإيثار –اللطف والكياسة)، في حين يتوسط بشكل جزئي العلاقة ما بين قيم الثقة التنظيمية وأبعاد (الروح الرياضية – السلوك الحضاري – وعي الضمير) لسلوك المواطنة التنظيمية. الكلمات المفتاحية: الدعم التنظيمي المدرك، سلوك المواطنة التنظيمية، قيم الثقة التنظيمية.The present study aimed at identifying the effect of organizational support, which is perceived as an intermediate variable, on the values of organizational confidence ​​and the behavior of organizational citizenship at Al-Aqsa University represented by five dimensions (altruism, kindness, politeness, cultural behavior, conscience). To achieve the objectives of the study, the researcher designed a questionnaire consisting of (33) items to collect the data.&nbsp; The questionnaire was distributed to a sample of (149) university staff. The researcher used the descriptive method. After the statistical analysis of the data, results revealed that the level of perceptions of employees of Al-Aqsa University for the prevailing organizational confidence values ​​was medium. The degree of practicing the behavior of organizational citizenship by Al-Aqsa University staff was also&nbsp; medium, whereas their level of awareness of organizational support was high. The results also indicated that the perceived organizational support is exactly in the middle of the relationship between the values ​​of organizational confidence and the behavior of organizational citizenship in the dimensions of (altruism – kindness and politeness), while the relationship was partly mediating between the values ​​of organizational confidence and the dimensions of (athletic spirit, civilized behavior, and conscience). Keywords: Perceived organizational support, Organizational citizenship behavior, Organizational confidence value

Mineral and heavy metals content in tilapia fish (Oreochromis niloticus) collected from the River Nile in Damietta governorate, Egypt and evaluation of health risk from tilapia consumption

This study was conducted to determine heavy metals and trace elements content in tilapia fish collected from three sources in Damietta governorate, Egypt and to evaluate the human health risk due to tilapia consumption. Tilapia samples were collected from two locations in the River Nile stream, tow fish farms and two sluiceways. Health risk assessment was evaluated based on the consumption habits of adult human. The results revealed that all samples vary in elements concentrations. The calculation of human health risk revealed that the consumption of tilapia in the three tested area does not pose any health risk except for Selenium. It could be concluded that consumption of such fish may be a risk for consumers who eat fish more than one time per week. Consequently, precautions should be taken and warning against eating tilapia fish caught from these regions should be announced.This study was conducted to determine heavy metals and trace elements content in tilapia fish collected from three sources in Damietta governorate, Egypt and to evaluate the human health risk due to tilapia consumption. Tilapia samples were collected from two locations in the River Nile stream, tow fish farms and two sluiceways. Health risk assessment was evaluated based on the consumption habits of adult human. The results revealed that all samples vary in elements concentrations. The calculation of human health risk revealed that the consumption of tilapia in the three tested area does not pose any health risk except for Selenium. It could be concluded that consumption of such fish may be a risk for consumers who eat fish more than one time per week. Consequently, precautions should be taken and warning against eating tilapia fish caught from these regions should be announced

An investigation of the mechanical properties of ternary blend cement pasts containing a large amount of cement kiln dust

Cement kiln dust is a by-product of the cement industry composed of particles of feedstock and condensed volatilized inorganic salts. The effect of Cement kiln dust (CKD) on the mechanical properties of ternary blend cement pastes was studied by preparing different mixes using 40%CKD, 10% OPC and 50% of three different pozzolanic material (ground granulated blast furnace slag (GGBFS), metakaolin (MK), and ground clay brick (GCB)). The mechanical properties were tested via the determination of compressive strength, bulk density, total porosity, and chemically combined water content at 3, 7, 28, 90, and 180 days. The hydration products were evaluated using x-ray diffraction analysis. The result indicated that 40%CKD greatly enhances the activation of GGBFS, MK, and GCB. The paste that contains (10% OPC, 40% CKD, and 50% GGBFS) gives the highest compressive strength, while (10% OPC, 40% CKD, and 50% GCB) gives the lowest compressive strength

Geological and Geotechnical Assessment of Gabal Ataqa Dolostones, for Pavement Construction in Egypt

Aggregate is a collective term for the mineral materials such as sand, gravel and crushed stone. By weight, aggregate generally occupies about 92-96 percent of the hot mix asphalt (HMA), and about 79-85 percent of the Portland cement concrete (PCC). Aggregate is also used for Base and Sub-base courses for both flexible and rigid pavements. This research aims to investigate the geological and geotechnical properties of Gabal Ataqa dolostone for pavement construction projects in Egypt. A total of six dolomite microfacies were recognized and classified according to the dolomite rock classification. The X-Ray Diffraction (XRD) analysis showed that Ataqa dolostones consist mainly of dolomite (89.79%) and calcite (7.74%), while quartz (2.3 %) and halite (0.18 %) were found in small amounts in some samples. Generally Ataqa dolostone is around stoichiometric (50.96%), and may belong to dolomite of late diagentic coarse crystalline dolomite. The chemical investigation showed that the major elements of the investigated dolostone rocks are SiO2 (1.72 %); CaO (32.03%), MgO (19.18%), Fe2O3 (0.22 %), Na2O (0.11%), and Al2O3 (0.05%) while the loss on ignition is about (46.19 %.). The trace elements consist of strontium (116 ppm), barium (14.0 ppm); and very low amount of zirconium (3 ppm). Petrographic, chemical, mineralogical, and compressive strength of Ataqa dolostone rocks beside, geotechnical properties of the produced coarse aggregates were investigated. Los Angeles abrasion, apparent specific gravity, water absorption, disintegration, and stripping were evaluated. The results of the conducted testing indicate that Ataqa dolostone rocks are suitable for road construction and concrete industry.

Construction of a New Method for Easy Fitting Block Pattern uitable for Egyptian Women and Comparing it to the Borgo Method

Constructing a basic block pattern is an essential step that covers all body types, and therefore can be applied to any design and any type of clothing. This means, constructing a suitable basic block pattern increases the quality of the pieces of clothes. So, it calls for the technical side in the analysis of the design accurately and understand the type and construction of fabric used, and between the practical side in taking the body measurements accurately and add the appropriate ease amount of comfort for a good fitting for all sizes, and gives the appropriate effect in terms of fit, comfort, and drape. Therefore, the aim of the research focused on constructing an easy-fitting block pattern of the blouse to suit the body of the Egyptian woman. The results showed that the new suggested method is better than the method of Fernando Borgo (B) as such, the study recommended the importance of studying the easy fitting block and studying the pattern making as one of the main factors for the quality of the final product

Autism and Fragile X: Is There a Neurochemical Link?

BACKGROUND:Autism and Fragile X syndrome are intertwined. This study aimed at assessing Serotonin, Glutamate, and Gama Amino Butyric Acid (GABA) in autism and Fragile X syndrome patients and to detect possible neurochemical similarities between the 2 disorders that can be used as metabolic biomarkers.DESIGN AND METHODS: Eighty subjects divided into four groups, two diseased groups (20 male patients with Autism and 20 males with Fragile X syndrome) and two control groups (20 neurotypical male controls and 20 Down syndrome male patients) were included. Estimation of Serotonin, Glutamate and GABA were done using Enzyme linked Immunosorbent Assay (ELISA), Tandem Mass Spectrometry and high-pressure liquid chromatography (HPLC), respectively.RESULTS: Serotonin was, exclusively, significantly low in autistic children. GABA was significantly high in both autistic and Fragile X children only, but not in Down syndrome children. Glutamate was significantly high in children with autism, Fragile X and Down syndrome Children.CONCLUSIONS: Autism and Fragile X syndrome share some neurochemical similarities with regards of high Glutamate and GABA levels while Serotonin was significantly different in the 2 disorders and may be used a unique biomarker for autism

Semantic prioritization of novel causative genomic variants

Discriminating the causative disease variant(s) for individuals with inherited or de novo mutations presents one of the main challenges faced by the clinical genetics community today. Computational approaches for variant prioritization include machine learning methods utilizing a large number of features, including molecular information, interaction networks, or phenotypes. Here, we demonstrate the PhenomeNET Variant Predictor (PVP) system that exploits semantic technologies and automated reasoning over genotype-phenotype relations to filter and prioritize variants in whole exome and whole genome sequencing datasets. We demonstrate the performance of PVP in identifying causative variants on a large number of synthetic whole exome and whole genome sequences, covering a wide range of diseases and syndromes. In a retrospective study, we further illustrate the application of PVP for the interpretation of whole exome sequencing data in patients suffering from congenital hypothyroidism. We find that PVP accurately identifies causative variants in whole exome and whole genome sequencing datasets and provides a powerful resource for the discovery of causal variants.NS was funded by Wellcome Trust (Grant 100585/Z/12/Z) and the National Institute for Health Research Cambridge Biomedical Research Centre. IB, RBMR, MK, YH, VBB, RH were funded by the King Abdullah University of Science and Technology. GVG acknowledges funding from the National Science Foundation (NSF grant number: IOS-1340112) and the European Commision H2020 (Grant Agreement No. 731075)