A review on cement degradation under CO2-rich environment of sequestration projects

Global warming arising from the release of greenhouse gasses into the atmosphere is one of the biggest issues attracting a lot of attention. One of the conventional problems in sequestration projects is the degradation of Portland cement due to its exposure to supercritical CO2. This paper gives a review on the laboratory work performed to understand changes in the mechanical and transport properties of cement when it is in a CO2 rich environment. The results obtained indicated that pozzolanic material could be useful in enhancing the cement resistance against CO2, although more studies are still required to confirm this conclusion

ISOLATION OF ASTRAGALIN FROM IRAQI CHENOPODIUM ALBUM

Objective: Chenopodium album L is the species of the genus chenopodium. The Greek name Chenopodium means goosefoot. The plant is native to Asia and Europe. The analysis of the constituents of the Iraqi plant was performed using gas chromatography and high-performance liquid chromatography techniques.Methods: Thin-layer chromatography (TLC) and high-performance TLC chromatographic techniques were used for the detection and isolation of the active constituent found in the plant. Spectral analysis such as nuclear magnetic resonance (NMR) and UV was used to confirm the chemical structure of the compound isolated.Results: Astragalin was isolated and identified by comparison with standard kaempferol 3-O-β-glucoside (astragalin) which was detected as the major glycoside in the polar fraction of the plant. Further, identification of the compound was performed by 1H-NMR spectroscopy.Conclusion: Astragalin is the major flavonoid glycoside found in the plant.Â

Imaging algorithm for COVID-19: A practical approach

© 2020 Elsevier Inc. The global pandemic of COVID-19 pneumonia caused by the novel coronavirus (SARS-CoV-2) has strained healthcare resources across the world with emerging challenges of mass testing, resource allocation and management. While reverse transcriptase-polymerase chain reaction (RT-PCR) test is the most commonly utilized test and considered the current gold standard for diagnosis, the role of chest imaging has been highlighted by several studies demonstrating high sensitivity of computed tomography (CT). Many have suggested using CT chest as a first-line screening tool for the diagnosis of COVID-19. However, with advancement of laboratory testing and challenges in obtaining a CT scan without significant risk to healthcare providers, the role of imaging in diagnosis has been questioned. Several imaging societies have released consensus statements and guidelines on utilizing imaging resources and optimal reporting. In this review, we highlight the current evidence on various modalities in thoracic imaging for the diagnosis of COVID-19 and describe an algorithm on how to use these resources in an optimal fashion in accordance with the guidelines and statements released by major imaging societies

ICASENSE : une application de l'analyse en composantes indépendantes à l'IRM parallèle

Les récentes méthodes d'imagerie IRM parallèle (SENSE et SMASH) nécessitent une bonne connaissance de la sensibilité des antennes. Celle ci est généralement mesurée lors d'une phase de calibration, ou estimée par filtrage adaptatif spatio-temporel si l'on dispose d'une série d'acquisitions (TSENSE). Nous proposons une formulation du problème en termes de séparation aveugle de sources : une analyse en composantes indépendantes (ICA) permet alors d'extraire les informations de sensibilité des antennes à partir d'une seule acquisition. Des résultats de simulations sont présentés, démontrant l'intérêt de cette nouvelle méthode que nous nommerons ICASENSE

Phonon-assisted radiofrequency absorption by gold nanoparticles resulting in hyperthermia

It is suggested that in gold nanoparticles (GNPs) of about 5 nm sizes used in the radiofrequency (RF) hyperthermia, an absorption of the RF photon by the Fermi electron occurs with involvement of the longitudinal acoustic vibrational mode (LAVM), the dominating one in the distribution of vibrational density of states (VDOS). This physical mechanism helps to explain two observed phenomena: the size dependence of the heating rate (HR) in GNPs and reduced heat production in aggregated GNPs. The argumentation proceeds within the one-electron approximation, taking into account the discretenesses of energies and momenta of both electrons and LAVMs. The heating of GNPs is thought to consist of two consecutive processes: first, the Fermi electron absorbs simultaneously the RF photon and the LAVM available in the GNP; hereafter the excited electron gets relaxed within the GNP's boundary, exciting a LAVM with the energy higher than that of the previously absorbed LAVM. GNPs containing the Ta and/or Fe impurities are proposed for the RF hyperthermia as promising heaters with enhanced HRs, and GNPs with rare-earth impurity atoms are also brought into consideration. It is shown why the maximum HR values should be expected in GNPs with about 5-7 nm size.Comment: proceedings at the NATO Advanced Research workshop FANEM-2015 (Minsk, May 25-27, 2015). To be published in the final form in: "Fundamental and Applied NanoElectroMagnetics" (Springer Science + Business Media B.V.

Awareness and Use of Benzodiazepines in Healthy Volunteers and Ambulatory Patients Visiting a Tertiary Care Hospital: A Cross Sectional Survey

Background: Indiscriminate prescription of Benzodiazepines in Pakistan and subsequent availability over-the-counter without prescription is a major public health problem, requiring systematic inquiry through research. Additionally, there is limited data on the awareness and use of Benzodiazepines from developing countries making it impossible to devise meaningful health policies. Methodology/Principal Findings: This was an Observational, Cross-Sectional study. conducted at Aga Khan University. A total of 475 (58.5 % males, 41.5 % females) people visiting a tertiary care hospital were interviewed by means of a structured questionnaire. The results showed that majority of population was aware of one or more Benzodiazepines (80.4%) and 30.4 % had used them at some point in life. 42.4 % of the users had been using it for more than a year. Commonest reason for use was sleep disturbance. Frequency of usage was higher for females, married individuals, educated (.Grade12), high socioeconomic status and housewives. More (59%) were prescribed than not and of them most by GP (58.5%). Only 36.5% of them were particularly told about the long-term addiction potential by the use of these drugs. Conclusion: Easy availability, access to re-fills without prescription and self prescription compounded with the lack of understanding of abuse potential of benzodiazepines constitutes a significant problem demanding serious consideratio

A modified empirical criterion for strength of transversely anisotropic rocks with metamorphic origin

A modified empirical criterion is proposed to determine the strength of transversely anisotropic rocks. In this regard, mechanical properties of intact anisotropic slate obtained from three different districts of Iran were taken into consideration. Afterward, triaxial rock strength criterion introduced by Rafiai was modified for transversely anisotropic rocks. The criterion was modified by adding a new parameter α for taking the influence of strength anisotropy into consideration. The results obtained have shown that the parameter α can be considered as the strength reduction parameter due to rock anisotropy. The modified criterion was compared to the modified Hoek–Brown (Saroglou and Tsiambaos) and Ramamurthy criteria for different anisotropic rocks. It was concluded that the criterion proposed in this paper is a more accurate and precise criterion in predicting the strength of anisotropic rocks

Shear Wave Splitting Analysis to Estimate Fracture Orientation and Frequency Dependent Anisotropy

Shear wave splitting is a well-known method for indication of orientation, radius, and length of fractures in subsurface layers. In this paper, a three component near offset VSP data acquired from a fractured sandstone reservoir in southern part of Iran was used to analyse shear wave splitting and frequency-dependent anisotropy assessment. Polarization angle obtained by performing rotation on radial and transverse components of VSP data was used to determine the direction of polarization of fast shear wave which corresponds to direction of fractures. It was shown that correct implementation of shear wave splitting analysis can be used for determination of fracture direction. During frequency- dependent anisotropy analysis, it was found that the time delays in shear- waves decrease as the frequency increases. It was clearly demonstrated throughout this study that anisotropy may have an inverse relationship with frequency. The analysis presented in this paper complements the studied conducted by other researchers in this field of research