570 research outputs found

    Inter-species variation in the oligomeric states of the higher plant Calvin cycle enzymes glyceraldehyde-3-phosphate dehydrogenase and phosphoribulokinase

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    In darkened leaves the Calvin cycle enzymes glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoribulokinase (PRK) form a regulatory multi-enzyme complex with the small chloroplast protein CP12. GAPDH also forms a high molecular weight regulatory mono-enzyme complex. Given that there are different reports as to the number and subunit composition of these complexes and that enzyme regulatory mechanisms are known to vary between species, it was reasoned that protein-protein interactions may also vary between species. Here, this variation is investigated. This study shows that two different tetramers of GAPDH (an A2B2 heterotetramer and an A4 homotetramer) have the capacity to form part of the PRK/GAPDH/CP12 complex. The role of the PRK/GAPDH/CP12 complex is not simply to regulate the 'non-regulatory' A4 GAPDH tetramer. This study also demonstrates that the abundance and nature of PRK/GAPDH/CP12 interactions are not equal in all species and that whilst NAD enhances complex formation in some species, this is not sufficient for complex formation in others. Furthermore, it is shown that the GAPDH mono-enzyme complex is more abundant as a 2(A2B2) complex, rather than the larger 4(A2B2) complex. This smaller complex is sensitive to cellular metabolites indicating that it is an important regulatory isoform of GAPDH. This comparative study has highlighted considerable heterogeneity in PRK and GAPDH protein interactions between closely related species and the possible underlying physiological basis for this is discussed. © 2011 The Author(s)

    Menstrual pattern amongst adolescent girls: a cross sectional study from Raichur, Karnataka

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    Background: Menstrual disorders in adolescent age are quite different than in adult women, both for diagnostic and therapeutic management. We need to take into account the problems in normal initiation of menarche, hematological problems, general endocrine problems, and fragile emotional status at this tender age. The objective of the study was to study the patterns of menstrual disorders in adolescent girls.Methods: Cross sectional observational study was carried out in 200 adolescent girls, aged 12 to 19 years, among the students of S.R.P.S PU college and the district government Girls’ school in Raichur during the period of January 2017 to December 2017. A pre-structured questionnaire was used and data was analysed using Statistical package for social sciences (SPSS) 23.0 version.Results: Majority of the girls in our study were from 17-18 years age group (55%). The mean age of menarche was 13.2±0.9 years. Cycle length of 35 days cycle length. Majority had normal cycle length. Dysmenorrhea was found in 84 (42%) students. Premenstrual symptoms like tiredness were noted in 14 (7%) of cases, pain in the legs in 10 (5%), irritability in 8 (4%), lack of interest in work and play in 7 (3.5%), low back pain in 6 (3%), low/depressed mood in 6 (3%), anger in 4 (2%), anxiety in 4 (2%), difficulty in concentrating in 2 (1%), nausea\vomiting were noted in 2 (1%).Conclusions: Prevalence of dysmenorrhea was 42%. Premenstrual symptoms like tiredness were noted in majority of the girls 7%, pain in the legs in 5%, irritability in 4%

    Galvanic exchange as a novel method for carbon nitride supported coag catalyst synthesis for oxygen reduction and carbon dioxide conversion

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    A bimetallic alloy of CoAg nanoparticles (NPs) on a carbon nitride (CN) surface was synthesized using a galvanic exchange process for the oxygen reduction reaction (ORR) and carbon dioxide electrocatalytic conversion. The reduction potential of cobalt is ([Co2+(aq) + 2e? ? Co(s)], ?0.28 eV) is smaller than that of Ag ([Ag+(aq) + e? ? Ag(s)], 0.80 eV), which makes Co(0) to be easily replaceable by Ag+ ions. Initially, Co NPs (nanoparticles) were synthesized on a CN surface via adsorbing the Co2+ precursor on the surface of CN and subsequently reducing them with NaBH4 to obtain Co/CN NP. The Co NPs on the surface of CN were then subjected to galvanic exchange, where the sacrificial Co atoms were replaced by Ag atoms. As the process takes place on a solid surface, only the partial replacement of Co by Ag was possible generating CoAg/CN NPs. Synthesized CoAg/CN bimetallic alloy were characterized using different techniques such as powder x-ray diffraction (PXRD), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electron diffraction spectroscopy (EDS) to confirm the product. Both the catalysts, Co/CN and CoAg/CN, were evaluated for oxygen reduction reaction in 1M KOH solution and carbon dioxide conversion in 0.5 M KHCO3. In the case of ORR, the CoAg/CN was found to be an efficient electrocatalyst with the onset potential of 0.93 V, which is comparable to commercially available Pt/C having Eonset at 0.91 V. In the electrocatalytic conversion of CO2, the CoAg/CN showed better performance than Co/CN. The cathodic current decreased dramatically below ?0.9V versus Ag/AgCl indicating the high conversion of CO2. - 2019 by the authors. Licensee MDPI, Basel, Switzerland.Acknowledgements: The authors would like to gratefully acknowledge financial support from Total Research & Technology Feluy (Grant Number: QUEX-CENG-TRT-17/18) in conducting this research. The statements made herein are solely the responsibility of the authors. The authors also wish to gratefully acknowledge the Gas Processing Centre (GPC) at Qatar University for carrying out XRD and XPS analysis, and the Central Laboratory Unit (CLU) at Qatar University for services related to electron microscopy.Scopu

    The impact of mechanical shear on membrane flux and energy demand

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    The use of forced mechanical shear for both disc membranes (rotating and vibrating disc filtration, RDF and VDF respectively) and hollow fibres (vibrating HF membranes, VHFM) is reviewed. These systems have been extensively studied and, in the case of the disc membranes, have reached commercialisation and proven effective in achieving transmembrane pressure (TMP) control for various challenging feed waters. The effects of operating conditions, namely shear rate as enhanced by rotation and vibration speed and TMP, and feed water quality on the filtration flux and specific energy consumption are quantified as part of the review. A new relationship is revealed between the two empirical constants governing the classical relationship between membrane flux and shear rate, and a mathematical correlation proposed accordingly. A study of available information on energy reveals that operation at lower shear rates (i.e. rotation or vibration speeds) and more conservative fluxes leads to lower specific energy demands in kWh m−3 permeate, albeit with a larger required membrane area

    Performance evaluation of the dynamic trajectory design for an unmanned aerial base station in a single frequency network

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    Using an Unmanned Aerial Base Station (UABS) i.e., a base station carried by a UAV (Unmanned Aerial Vehicle) or drone, is a promising approach to offer coverage and capacity to those users that are not being served by the base stations of the terrestrial network. In this paper, we propose an approach to the design of the drone's trajectory to account for the quickly varying user traffic and pattern. This approach is based on the identification of clusters made of nearby users to be served. The decision on which cluster to visit next by the UABS depends on a cost-function considering the distance to the next cluster, the user density and spread in the cluster, and the direction compared to the previously visited cluster. Furthermore, we propose a radio resource assignment algorithm to minimize the interference from the UABS to the terrestrial network when both are operating in the same frequency band. The potential improvements in terms of network capacity (sum throughput) and user satisfaction are estimated in this study

    Prevalence of somatisation and psychologisation among patients visiting primary health care centres in the State of Qatar

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    Background: Medically unexplained somatic complaints are among the most common clinical presentations in primary care in developing countries and they are considerable burden for patients and health care system. Objectives: The aim of this study was to determine the prevalence of somatisation in comparison to psychologisation among a sample of Qatari patients who were visiting primary health care (PHC) centres and to investigate the clinical and socio-demographic characteristics of somatisers (STs) and psychologisers (PGs). Method: The survey was conducted among PHC Qatari patients during the period from January to July 2007. About 2,320 patients were approached, of whom 1,689 agreed to participate and responded to the questionnaire. Among the studied Qatari patients, 404 patients were identified for clinical interview. The first stage of the study was conducted with the help of general practitioners, using the 12-item General Health Questionnaire. The second stage was carried out by a consultant using the Clinical Interview Schedule. A specific operational criterion was used to identify STs and PGs. Results: The prevalence rate of STs among the total studied sample was 12.4%, while the PGs were 11.5%. Among the identified psychiatric cases, the proportion of STs (52%) was higher than PGs (48%). Most of the diagnostic categories were more prevalent among PGs. The dissatisfaction at work and stressful life events within 12 months before the onset of the presenting symptoms were the three postulated determinants which were significantly more among STs than PGs. Conclusion: The prevalence of somatised mental disorder was little higher than the psychologised mental disorder. The prevalence of somatisation and psychologisation is comparable with other reported studies from the Middle-East and Western countries. Dissatisfaction at work and stressful life events were significantly higher among STs than PGs.Keywords: somatisers; psychologisers; primary health care; determinants; Arab cultur
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