308 research outputs found

    Experimental behavior of full-scale exterior beam-column space joints retrofitted by ferrocement layers under cyclic loading

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    A majority of the traditional reinforced concrete frame buildings, existing across the Middle East, lack adequate confinement in beam-column joints, or in other words, are shear deficient because they were constructed before the introduction of seismic codes for construction. This research studies the experimental behavior of full-scale beam-column space (three-dimensional) joints under displacement-controlled cyclic loading. Eleven joint specimens, included a traditionally reinforced one (without adequate shear reinforcement), a reference one with sufficient shear reinforcement according to ACI 318, and nine specimens retrofitted by ferrocement layers, were experimentally tested to evaluate a retrofit technique for strengthening shear deficient beam column joints. The studied variables were the number of layers, orientation angle of expanded wire mesh per layer, and presence of steel angles in the corners of joint specimen prior to wrapping with ferrocement layers. The experimental results showed that proper shear reinforcement for the test joints, according to ACI 318, enhanced the behavior of the specimen over that of the traditionally reinforced specimens without adequate shear reinforcement. The joints retrofitted by ferrocement layers showed higher ultimate capacity, higher ultimate displacement prior to failure (better ductility), and they did not suffer heavily damage as observed for the traditionally reinforced one. Increasing the number of ferrocement layers for retrofitted specimens led to improving performance for such specimens compared to the traditionally reinforced ones in terms of enhancing the ultimate capacity and ultimate displacement. Specimens retrofitted by ferrocement layers reinforced by expanded wire mesh of 60° orientation angle showed slightly better performance than those of 45° orientation angles. Retrofitting using steel angles in addition to ferrocement layers improves the seismic performance of the specimens, achieves better stability for stiffness degradation, attains higher capacity of the dissipated energy, and reduces the vulnerability of joints to excessive damage. Based on the experimental work in this study, it is recommended to retrofit beam-column joint specimens by two ferrocement layers in addition to steel angles as stiffeners taking the orientation angle of expanded wire mesh into consideration. Keywords: Retrofitting, Beam-column space joints, Ferrocement layers, Orientation of expanded wire mesh, Ultimate capacity, Stiffness degradation, Cyclic loading, Shear deficient, Traditionally reinforced building

    Studies on new antifreeze protein from the psychrophilic diatom, Fragilariopsis cylindrus

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    Antifreeze proteins (AFPs) are found in a wide range of species including fishes, plants, etc. They have very characteristic feature that inhibit the growth and recrystallization of ice that forms in intercellular spaces. Two expressed sequence tags (ESTs) were previously identified from salt stress cDNA library in Fragilariopsis cylindrus to have similarities with snow mold AFP. Using bioinformatics tools, we analysed these two AFP-ESTs. Accordingly, by using specially designed primers, the open reading frames (ORFs) subcloned into bacterial and plant expression vectors. The predicted gene product, AfpA, had a molecular mass of 27 kDa. Expression of afpA in Escherichia coli yielded an intracellular 27-kDa protein modified with His-tag. According to bioinformatics data, a comparison between AFP-A and carrot AFP has been carried out.Key words: Antifreeze protein, Fragilariopsis cylindrus, recrystallization inhibition

    Optimizing Deep Learning Model Parameters with the Bees Algorithm for Improved Medical Text Classification

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    This paper introduces a novel mechanism to obtain the optimal parameters of a deep learning model using the Bees Algorithm, which is a recent promising swarm intelligence algorithm. The optimization problem is to maximize the accuracy of classifying ailments based on medical text given the initial hyper-parameters to be adjusted throughout a definite number of iterations. Experiments included two different datasets: English and Arabic. The highest accuracy achieved is 99.63% on the English dataset using Long Short-Term Memory (LSTM) along with the Bees Algorithm, and 88% on the Arabic dataset using AraBERT

    Anti-quorum sensing activity of some medicinal plants

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    Background: Quorum sensing is the key regulator of virulence factors of Pseudomonas aeruginosa such as biofilm formation, motility, productions of proteases, hemolysin, pyocyanin, and toxins. The aim of this study was to explore the effect of the extracts from some medicinal plants on quorum sensing and related virulence factors of P. aeruginosa.Material and Methods: Quorum sensing inhibitory (OSI) effect of the alcohol extracts of 20 medicinal plants was evaluated by Chromobacterium violaceum reporter using agar cup diffusion method. The efficient QSI extracts were tested for their activity against biofilm synthesis, motility, and synthesis of pyocyanin from P. aeruginosa PA14Results: The extracts of Citrus sinensis, Laurus nobilis, Elettaria cardamomum, Allium cepa, and Coriandrum sativum exhibited potent quorum quenching effect. On the other hand, Psidium guajava and Mentha longifolia extracts showed lower QSI activity. These extracts exhibited significant elimination of pyocyanin formation and biofilm development of Pseudomonas aeruginosa PA14. In addition, they significantly inhibited twitching and swimming motilities of P. aeruginosa PA14.Conclusion: This study illustrated, for the first time, the importance of C. sinensis, L. nobilis, E. cardamomum, A. cepa, and C. sativum as quorum sensing inhibitors and virulence suppressors of P. aeruginosa. Thus, these plants could provide a natural source for the elimination of Pseudomonas pathogenesis.Keywords: Quorum sensing inhibitory activity, P. aeruginosa, Chromobacterium violaceum, virulence factor

    Examining the cancellation mechanism of neutron EDM in a model with dilaton-dominated susy breaking

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    We examine the cancellation mechanism between the different contributions to the electric dipole moment of the neutron in a model with dilaton-dominated SUSY breaking. We find these accidental cancellations occur at few points in parameter space. For a wide region of this space we must constrain the phase of μ\mu to be of order 10110^{-1} and have the phases of AA and μ\mu strongly correlated in order to have small neutron EDM. Moreover, we consider the indirect CP violation parameter ϵ\epsilon in this region where the electric dipole moment is less than the experimental limit and find that we can generate ϵ\epsilon of order 10610^{-6}

    Terretonin N: A New Meroterpenoid from Nocardiopsis sp.

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    Hamed A, Abdel-Razek AS, Frese M, et al. Terretonin N: A New Meroterpenoid from Nocardiopsis sp. Molecules. 2018;23(2): 299.Terretonin N (1), a new highly oxygenated and unique tetracyclic 6-hydroxymeroterpenoid, was isolated together with seven known compounds from the ethyl acetate extract of a solid-state fermented culture of Nocardiopsis sp. Their structures were elucidated by spectroscopic analysis. The structure and absolute configuration of 1 were unambiguously determined by X-ray crystallography. The isolation and taxonomic characterization of Nocardiopsis sp. is reported. The antimicrobial activity and cytotoxicity of the strain extract and compound 1 were studied using different microorganisms and a cervix carcinoma cell line, respectively

    Neurological presentation predicting immune thrombotic thrombocytopenic purpura outcome

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    Introduction: Immune thrombotic thrombocytopenic purpura (iTTP) is a rare disorder caused by acquired autoantibodies to a disintegrin and metalloprotease with thrombospondin-1 motifs (ADAMTS-13) that normally cleaves von Willebrand factor macromolecules. It is manifested by microangiopathic hemolytic anemia, systemic microvascular thrombi formation, and subsequent end-organ ischemia (renal and neurological manifestations). Early diagnosis and management resulted in improving the survival rate. This is a retrospective study conducted to describe the clinical characteristics of patients diagnosed with iTTP, their survival, and prognostic factors affecting it. Methods: We included adult patients who met the diagnostic criteria of iTTP between 2016 and 2019. Based on PLASMIC Score for TTP, our patients ranged from 6 to 7. ADAMTS-13 testing was not done because of financial issues. Results: A total of 21 patients were included in this study. The median age of the studied patients was 30.45 years, and 81% of them were female. The most common clinical feature was fever (57.1%), followed by bleeding manifestations (52.4%), neurological manifestations (47.6%), renal impairment (42.9%), and cardiac manifestations (9.5%). There were a total of 4 deaths (19.04%). The overall survival was correlated significantly with neurological manifestations and PLASMIC scores (p = 0.02, 0.012, respectively). Conclusions: Our report reinforces that iTTP is not mandatory to be presented with classic pentad. Using PLASMIC score could help in the diagnosis and prediction of survival, and we strongly suggest that the absence of neurological manifestations  results in better overall survival. Therapeutic plasma exchange should be started as soon as possible once iTTP is suspected. Rituximab has an important role in improving treatment outcomes

    Biliary fistula and late recurrence of liver hydatid cyst: Role of cysto-biliary communication: A prospective multicenter study

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    Background: Hydatid cyst disease (HCD) is common in certain locations. Surgery is associated with postoperative biliary fistula (POBF) and recurrence. The primary aim of this study was to identify whether occult cysto-biliary communication (CBC) can predict recurrent HCD. The secondary aim was to assess the role of cystic fluid bilirubin and alkaline phosphatase (ALP) levels in predicting POBF and recurrent HCD. Aim: To identify whether occult CBC can predict recurrent HCD. The secondary aim was to assess the role of cystic fluid bilirubin and ALP levels in predicting POBF and recurrent HCD. Methods: From September 2010 to September 2016, a prospective multicenter study was undertaken involving 244 patients with solitary primary superficial stage cystic echinococcosis 2 and cystic echinococcosis 3b HCD who underwent laparoscopic partial cystectomy with omentoplasty. Univariable logistic regression analysis assessed independent factors determining biliary complications and recurrence. Results: There was a highly statistically significant association (P ≤ 0.001) between cystic fluid biochemical indices and the development of biliary complications (of 16 patients with POBF, 15 patients had high cyst fluid bilirubin and ALP levels), where patients with high bilirubin-ALP levels were 3405 times more likely to have biliary complications. There was a highly statistically significant association (P ≤ 0.001) between biliary complications, biochemical indices, and the occurrence of recurrent HCD (of 30 patients with recurrent HCD, 15 patients had high cyst fluid bilirubin and ALP; all 16 patients who had POBF later developed recurrent HCD), where patients who developed biliary complications and high bilirubin-ALP were 244.6 and 214 times more likely to have recurrent hydatid cysts, respectively. Conclusion: Occult CBC can predict recurrent HCD. Elevated cyst fluid bilirubin and ALP levels predicted POBF and recurrent HCD

    Influence of blended powders on properties of ultra-high strength fibre reinforced self compacting concrete subjected to elevated temperatures

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    Ultra-High Strength Fibre Reinforced Self Compacting Concrete (UHSFRSCC) is in great demand for use in construction projects around the globe. Unless fillers are utilized in this concrete, its production will come at an excessive environmental cost due to the high Carbon footprint of Portland cement. A gap in the published literature was identified, where quaternary mixes, containing Portland cement with three fillers, incorporating fibres, and achieving ultra high strength, were not cited. In this study ternary and quaternary mixes were designed and produced, satisfying the European Guidelines for SCC, with compressive strengths exceeding 115 MPa. Some mixes had compressive strengths between 125 – 150 MPa, which were not previously reported in the literature. The mixes contained Silica Fume (SF), Metakaolin (MK), Limestone powder (LS) as partial Portland cement replacement and quartz powder (QP) as partial sand replacement. Basalt Fibres were added to reinforce the matrix. Compressive & tensile strength of the mixes along with UPV, sorptivity, absorption and SEM Micro-structure features were studied at ambient temperature and after the samples were exposed to either 200 or 300 oC; since the behavior of HSC at elevated temperature is always a cause for concern. The active and inert fillers exhibited a synergic behavior at all temperature conditions. The mix containing: 15% SF, 5% MK, 20% LS and 34% QP achieved the best performance. Compressive and splitting tensile strength improve by 10% and 17% while sorptivity and absorption decline by 40% and 29% respectively at ambient temperature. Residual compressive strength improved by 10% and 19% while, residual splitting tensile strength significantly increases by 21% and 28% after exposure to elevated temperatures 200°C and 300°C respectively. Meanwhile, residual sorptivity decreases by 39% and 38% after exposure to these elevated temperatures. Microstructure properties supported and agreed with the mechanical and permeation characteristics results. The results will contribute to the development of UHSFRSCC in hot weather countries
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