Search for: analytical-parameters
0.006 seconds

    Two statistical methods for resolving healthy individuals and those with congestive heart failure based on extended self-similarity and a recursive method

    , Article Journal of Biological Physics ; Volume 32, Issue 6 , 2006 , Pages 489-495 ; 00920606 (ISSN) Atyabi, F ; Livari, M. A ; Kaviani, K ; Rahimi Tabar , M. R ; Sharif University of Technology
    In this paper we introduce two methods for measuring irregularities in human heartbeat time series (HHTS). First we consider the multi-fractal structure of HHTS to distinguish healthy individuals and from those with congestive heart failure. In this way we modify the Extended Self-Similarity (ESS) method and apply it to HHTS. Our second approach is based on the recursive method, which we use to predict the duration of the next heartbeat by considering a few previous ones. We use standard physiological data and show that these approaches lead to very satisfactory methods to resolve the healthy and CHF individuals. These methods can be used potentially in portable electronic heart alarm... 

    The sources of stigma and the impacts on Afghan refugees with substance abuse disorders: A qualitative study in Iran

    , Article Journal of Ethnicity in Substance Abuse ; Volume 19, Issue 4 , 2020 , Pages 610-622 Deilamizade, A ; Moghanibashi Mansourieh, A ; Mohammadian, A ; Puyan, D ; Sharif University of Technology
    Routledge  2020
    Iran is the fourth refugee-hosting country and Afghanistan is the second refugee-source country in the world. This research is qualitative and conducted with content analysis method. Twenty-seven individuals participated in the study. They were recruited from two midterm residential drug treatment centers in Tehran. Afghan refugees who use drugs felt and experienced stigma in five areas: family, friends, workplace, neighborhood, and treatment center. The consequences include frequent treatment failure, family relationship disruption, superficial conformity with the host society, and self-stigma. It is necessary to design interventions to reduce stigma and discrimination attached to refugees.... 

    An investigation into the energy transfer efficiency of a two-pigment photosynthetic system using a macroscopic quantum model

    , Article BioSystems ; Volume 197 , 2020 Ghasemi, F ; Shafiee, A ; Sharif University of Technology
    Elsevier Ireland Ltd  2020
    Despite several different measures of efficiency that are applicable to the photosynthetic systems, a precise degree of efficiency of these systems is not completely determined. Introducing an efficient model for the dynamics of light-harvesting complexes in biological environments is a major purpose in investigating such systems. Here, we investigate the effect of macroscopic quantum behavior of a system of two pigments on the transport phenomena in this system model which interacts with an oscillating environment. We use the second-order perturbation theory to calculate the time-dependent population of excitonic states of a two-dimensional Hamiltonian using a non-master equation approach.... 

    Effect of bubble size and angle of tapering upriser pipe on the performance of airlift pumps

    , Article Particulate Science and Technology ; Volume 28, Issue 4 , Aug , 2010 , Pages 332-347 ; 02726351 (ISSN) Hanafizadeh, P ; Saidi, M. H ; Karimi, A ; Zamiri, A ; Sharif University of Technology
    Airlift pumps are devices with the ability to lift liquid phase by injecting the gas phase. Parameters that affect the performance of these pumps are divided into two groups. The first group contains design parameters such as diameter of the pipe, tapering angle of the upriser pipe, and the submergence ratio, which is the ratio of immersed length to the total length of the upriser. The second group includes operating parameters such as the gas flow rate, bubble diameter, bubble distribution, and inlet gas pressure. In this research, the performance of an airlift pump is investigated numerically for different submergence ratios and different diameter of the upriser pipe. For this purpose, an... 

    A systematic study on the effect of noise and shift on multivariate figures of merit of second-order calibration algorithms

    , Article Analytica Chimica Acta ; Volume 952 , 2017 , Pages 18-31 ; 00032670 (ISSN) Ahmadvand, M ; Parastar, H ; Sereshti, H ; Olivieri, A ; Tauler, R ; Sharif University of Technology
    Elsevier B.V  2017
    In the present study, multivariate analytical figures of merit (AFOM) for three well-known second-order calibration algorithms, parallel factor analysis (PARAFAC), PARAFAC2 and multivariate curve resolution-alternating least squares (MCR-ALS), were investigated in simulated hyphenated chromatographic systems including different artifacts (e.g., noise and peak shifts). Different two- and three-component systems with interferences were simulated. Resolved profiles from the target components were used to build calibration curves and to calculate the multivariate AFOMs, sensitivity (SEN), analytical sensitivity (γ), selectivity (SEL) and limit of detection (LOD). The obtained AFOMs for different... 

    A continuous flow microfluidic device based on contactless dielectrophoresis for bioparticles enrichment

    , Article Electrophoresis ; Volume 39, Issue 3 , 2018 , Pages 445-455 ; 01730835 (ISSN) Rahmani, A ; Mohammadi, A. A ; Kalhor, H. R ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    In recent years, applications of dielectrophoresis-based platforms have been recognized as effective and dependable approach to separate cells and bioparticles, suspended in different carrier fluids, based on particle size and electrical properties. In this study, a microfluidic device was fabricated by an unprecedented electrode pattern, and several experiments were performed to enrich samples including either of yeast, Escherichia coli, or latex particles. A chemical deposition-based method was employed for fabrication of microelectrodes, inducing nonuniform electric field required for dielectrophoresis-based separation. One major advantage of our employed method is low fabrication cost,... 

    Double network hydrogel of sodium alginate/polyacrylamide cross-linked with POSS: Swelling, dye removal and mechanical properties

    , Article International Journal of Biological Macromolecules ; Volume 129 , 2019 , Pages 187-197 ; 01418130 (ISSN) Bahrami, Z ; Akbari, A ; Eftekhari Sis, B ; Sharif University of Technology
    Elsevier B.V  2019
    In this work, for the first time, we presented a novel design strategy to fabricate a new type of Octa-aminopropyl polyhedral oligomeric silsesquioxane hydrochloride salt (OA-POSS)-based Alg/PAAm DN gels, consisting of PAAm gel as the first chemical network and Alg/OA-POSS gel as the second chemical-physical network. Incorporation of OA-POSS nanoparticles with various feed ratio into the second network not only led to form strong coordination interactions but also in comparison to the other Alg/PAAm gels demonstrated superior mechanical properties. pH, temperature, contact time and salt effects parameters were studied on the swelling and dye removal properties of the synthesized DN hybrid... 

    Qquantitative structure - retention relationship study of a variety of compounds in reversed-phase liquid chromatography: A PLS-MLR-STANN approach

    , Article QSAR and Combinatorial Science ; Volume 27, Issue 2 , 2008 , Pages 137-146 ; 1611020X (ISSN) Jalali Heravi, M ; Garkani Nejad, Z ; Kyani, A ; Sharif University of Technology
    A quantitative structure-retention relationships model has been developed to study the retention behavior of 87 aliphatic and aromatic compounds in Reversed-Phase Liquid Chromatography (RPLC) on five bonded-phase columns differing in silanol group acidity. Six numerical descriptors of Molecular Mass (M), partial charge of the most negative atom (NPCH), partial charge of the most positive hydrogen (PCHH), van der Waals volume (VOLUME), Dipole Moment (DIMO), and Highest Occupied Molecular Orbital (HOMO) have been calculated for each compound. A separate Multiple Linear Regression (MLR) model has been developed using the six descriptors for each column. Partial Least Square (PLS) combined with... 

    Model-based fiducial points extraction for baseline wandered electrocardiograms

    , Article IEEE Transactions on Biomedical Engineering ; Volume 55, Issue 1 , 2008 , Pages 347-351 ; 00189294 (ISSN) Sayadi, O ; Shamsollahi, M. B ; Sharif University of Technology
    A fast algorithm based on the nonlinear dynamical model for the electrocardiogram (ECG) is presented for the precise extraction of the characteristic points of these signals with baseline drift. Using the adaptive bionic wavelet transform, the baseline wander is removed efficiently. In fact by the means of the bionic wavelet transform, the resolution in the time-frequency domain can be adaptively adjusted not only by the signal frequency but also by the signal instantaneous amplitude and its first-order differential, which results in a better baseline wander cancellation. At the next step the parameters of the model are chosen to have the least square error with the original ECG. Determining... 

    A new detection chamber design on centrifugal microfluidic platform to measure hemoglobin of whole blood

    , Article SLAS Technology ; Volume 26, Issue 4 , 2021 , Pages 392-398 ; 24726303 (ISSN) Mahmodi Arjmand, E ; Saadatmand, M ; Eghbal, M ; Bakhtiari, M. R ; Mehraji, S ; Sharif University of Technology
    SAGE Publications Inc  2021
    Undoubtedly, microfluidics has been a focal point of interdisciplinary science during the last two decades, resulting in many developments in this area. Centrifugal microfluidic platforms have good potential for use in point-of-care devices because they take advantage of some intrinsic forces, most notably centrifugal force, which obviates the need to any external driving forces. Herein, we introduce a newly designed detection chamber for use on microfluidic discs that can be employed as an absorbance readout step in cases where the final solution has a very low viscosity and surface tension. In such situations, our chamber easily eliminates the air bubbles from the final solution without... 

    Three dimensional heat transfer modeling of gas-solid flow in a pipe under various inclination angles

    , Article Powder Technology ; Vol. 262, Issue. 1 , 2014 , pp. 223-232 ; ISSN: 0032-5910 Pishvar, M ; Saffar Avval, M ; Mansoori, Z ; Amirkhosravi, M ; Sharif University of Technology
    The turbulent heat transfer in gas-solid flows through an inclined pipe under various inclination angles is studied with constant wall heat flux. The hydrodynamic k- τ and kθ- τθ thermal two phase model is used in a lagrangian/Eulerian four way approach. The numerical results agreed reasonably with available experimental data in vertical and horizontal pipe flows. The effects of inclination angles on the flow patterns are reported. The pressure drop and Nusselt number are enhanced significantly as the inclination increases up to a certain angle. The mass loading ratio has influence on the optimal inclination angle. With increasing loading ratio, the optimal inclination angle of maximum... 

    Application of chitosan-citric acid nanoparticles for removal of chromium (VI)

    , Article International Journal of Biological Macromolecules ; Volume 80 , September , 2015 , Pages 431-444 ; 01418130 (ISSN) Bagheri, M ; Younesi, H ; Hajati, S ; Borghei, S. M ; Sharif University of Technology
    Elsevier  2015
    In the present study, CS-CA nanoparticle was prepared for forming a new amide linkage, by grafting the amino groups of CS in the presence of carboxylic groups of CA that acts as cross-linking agent. The as-prepared CS-CA nanoparticle samples were characterized by use of dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier-transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques, which showed that the cross-linking agent preserved during the chemical modifications. The adsorption capacity of the CS-CA nanoparticles for the removal of Cr (VI) in aqueous solution was studied. The adsorption equilibrium data... 

    Experimentally based pore network modeling of NAPL dissolution process in heterogeneous porous media

    , Article Journal of Contaminant Hydrology ; Volume 228 , November , 2020 Khasi, S ; Ramezanzadeh, M ; Ghazanfari, M. H ; Sharif University of Technology
    Elsevier B.V  2020
    Practical designs of non-aqueous phase liquids (NAPLs) remediation strategies require reliable modeling of interphase mass transfer to predict the retraction of NAPL during processes such as dissolution. In this work, the dissolution process of NAPL during two-phase flow in heterogeneous porous media is studied using pore-network modeling and micromodel experiments. A new physical-experimental approach is proposed to enhance the prediction of the dissolution process during modeling of interphase mass transfer. In this regard, the normalized average resident solute concentration is evaluated for describing the dissolution process at pore-level. To incorporate the effect of medium... 

    Electrochemical prostate-specific antigen biosensors based on electroconductive nanomaterials and polymers

    , Article Clinica Chimica Acta ; Volume 516 , 2021 , Pages 111-135 ; 00098981 (ISSN) Dowlatshahi, S ; Abdekhodaie, M. J ; Sharif University of Technology
    Elsevier B.V  2021
    Prostate cancer (PCa), the second most malignant neoplasm in men, is also the fifth leading cause of cancer-related deaths in men globally. Unfortunately, this malignancy remains largely asymptomatic until late-stage emergence when treatment is limited due to the lack of effective metastatic PCa therapeutics. Due to these limitations, early PCa detection through prostate-specific antigen (PSA) screening has become increasingly important, resulting in a more than 50% decrease in mortality. Conventional assays for PSA detection, such as enzyme-linked immunosorbent assay (ELISA), are labor intensive, relatively expensive, operator-dependent and do not provide adequate sensitivity.... 

    A novel magnetic poly(aniline-naphthylamine)-based nanocomposite for micro solid phase extraction of rhodamine B

    , Article Analytica Chimica Acta ; Volume 794 , 2013 , Pages 38-46 ; 00032670 (ISSN) Bagheri, H ; Daliri, R ; Roostaie, A ; Sharif University of Technology
    A novel Fe3O4-poly(aniline-naphthylamine)-based nanocomposite was synthesized by chemical oxidative polymerization process as a magnetic sorbent for micro solid phase extraction. The scanning electron microscopy images of the synthesized nanocomposite revealed that the copolymer posses a porous structure with diameters less than 50nm. The extraction efficiency of this sorbent was examined by isolation of rhodamine B, a mutagenic and carcinogenic dye, from aquatic media in dispersion mode. Among different synthesized polymers, Fe3O4/poly(aniline-naphthylamine) nanocomposite showed a prominent efficiency. Parameters including the desorption solvent, amount of sorbent, desorption time, sample... 

    Is independent component analysis appropriate for multivariate resolution in analytical chemistry?

    , Article TrAC - Trends in Analytical Chemistry ; Volume 31 , 2012 , Pages 134-143 ; 01659936 (ISSN) Parastar, H ; Jalali Heravi, M ; Tauler, R ; Sharif University of Technology
    In this article, we examine Independent Component Analysis (ICA) and the concept of Mutual information (MI) as a quantitative measure of independence from the point of view of analytical chemistry. We compare results obtained by different ICA methods with results obtained by Multivariate Curve Resolution Alternating Least Squares (MCR-ALS). These results have shown that, when non-negativity constraints are applied, values of MI increase considerably and the resolved components cannot anymore be considered to be independent (i.e. they can only be considered to be the " least dependent" components). MI values of profiles resolved by MCR-ALS and ICA did not differ significantly when... 

    Comparison of two mathematical models for correlating the organic matter removal efficiency with hydraulic retention time in a hybrid anaerobic baffled reactor treating molasses

    , Article Bioprocess and Biosystems Engineering ; Volume 35, Issue 3 , 2012 , Pages 389-397 ; 16157591 (ISSN) Ghaniyari Benis, S ; Martín, A ; Borja, R ; Martin, M. A ; Hedayat, N ; Sharif University of Technology
    A modelling of the anaerobic digestion process of molasses was conducted in a 70-L multistage anaerobic biofilm reactor or hybrid anaerobic baffled reactor with six compartments at an operating temperature of 26 °C. Five hydraulic retention times (6, 16, 24, 72 and 120 h) were studied at a constant influent COD concentration of 10,000 mg/L. Two different kinetic models (one was based on a dispersion model with first-order kinetics for substrate consumption and the other based on a modification of the Young equation) were evaluated and compared to predict the organic matter removal efficiency or fractional conversion. The first-order kinetic constant obtained with the dispersion model was... 

    Fuzzy C-means clustering for chromatographic fingerprints analysis: A gas chromatography-mass spectrometry case study

    , Article Journal of Chromatography A ; Volume 1438 , 2016 , Pages 236-243 ; 00219673 (ISSN) Parastar, H ; Bazrafshan, A ; Sharif University of Technology
    Fuzzy C-means clustering (FCM) is proposed as a promising method for the clustering of chromatographic fingerprints of complex samples, such as essential oils. As an example, secondary metabolites of 14 citrus leaves samples are extracted and analyzed by gas chromatography-mass spectrometry (GC-MS). The obtained chromatographic fingerprints are divided to desired number of chromatographic regions. Owing to the fact that chromatographic problems, such as elution time shift and peak overlap can significantly affect the clustering results, therefore, each chromatographic region is analyzed using multivariate curve resolution-alternating least squares (MCR-ALS) to address these problems. Then,...