Статті в журналах: "Chromatography modelling and simulation"

1

Zenhäusern, Reto, and David W. T. Rippin. "Modelling and simulation of multicomponent nonlinear chromatography." Computers & Chemical Engineering 22, no. 1-2 (January 1998): 259–81. http://dx.doi.org/10.1016/s0098-1354(96)00364-x.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Irankunda, Rachel, Jairo Andrés Camaño Echavarría, Cédric Paris, Loïc Stefan, Stéphane Desobry, Katalin Selmeczi, Laurence Muhr, and Laetitia Canabady-Rochelle. "Metal-Chelating Peptides Separation Using Immobilized Metal Ion Affinity Chromatography: Experimental Methodology and Simulation." Separations 9, no. 11 (November 14, 2022): 370. http://dx.doi.org/10.3390/separations9110370.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Metal-Chelating Peptides (MCPs), obtained from protein hydrolysates, present various applications in the field of nutrition, pharmacy, cosmetic etc. The separation of MCPs from hydrolysates mixture is challenging, yet, techniques based on peptide-metal ion interactions such as Immobilized Metal Ion Affinity Chromatography (IMAC) seem to be efficient. However, separation processes are time consuming and expensive, therefore separation prediction using chromatography modelling and simulation should be necessary. Meanwhile, the obtention of sorption isotherm for chromatography modelling is a crucial step. Thus, Surface Plasmon Resonance (SPR), a biosensor method efficient to screen MCPs in hydrolysates and with similarities to IMAC might be a good option to acquire sorption isotherm. This review highlights IMAC experimental methodology to separate MCPs and how, IMAC chromatography can be modelled using transport dispersive model and input data obtained from SPR for peptides separation simulation.

3

McCoy, M. A., A. I. Liapis, and K. K. Unger. "Applications of mathematical modelling to the simulation of binary perfusion chromatography." Journal of Chromatography A 644, no. 1 (July 1993): 1–9. http://dx.doi.org/10.1016/0021-9673(93)80113-m.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Burrell, Frances M., Phillip E. Warwick, Ian W. Croudace, and W. Stephen Walters. "Development of a numerical simulation method for modelling column breakthrough from extraction chromatography resins." Analyst 146, no. 12 (2021): 4049–65. http://dx.doi.org/10.1039/d0an02251a.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

A numerical simulation method was developed in LabVIEW using rate constants derived from batch experiments. The successful application to chromatographic breakthrough demonstrates potential for integration with automated radioanalytical systems.

5

Karlberg, Micael, João Victor de Souza, Lanyu Fan, Arathi Kizhedath, Agnieszka K. Bronowska, and Jarka Glassey. "QSAR Implementation for HIC Retention Time Prediction of mAbs Using Fab Structure: A Comparison between Structural Representations." International Journal of Molecular Sciences 21, no. 21 (October 28, 2020): 8037. http://dx.doi.org/10.3390/ijms21218037.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Monoclonal antibodies (mAbs) constitute a rapidly growing biopharmaceutical sector. However, their growth is impeded by high failure rates originating from failed clinical trials and developability issues in process development. There is, therefore, a growing need for better in silico tools to aid in risk assessment of mAb candidates to promote early-stage screening of potentially problematic mAb candidates. In this study, a quantitative structure–activity relationship (QSAR) modelling workflow was designed for the prediction of hydrophobic interaction chromatography (HIC) retention times of mAbs. Three novel descriptor sets derived from primary sequence, homology modelling, and atomistic molecular dynamics (MD) simulations were developed and assessed to determine the necessary level of structural resolution needed to accurately capture the relationship between mAb structures and HIC retention times. The results showed that descriptors derived from 3D structures obtained after MD simulations were the most suitable for HIC retention time prediction with a R2 = 0.63 in an external test set. It was found that when using homology modelling, the resulting 3D structures became biased towards the used structural template. Performing an MD simulation therefore proved to be a necessary post-processing step for the mAb structures in order to relax the structures and allow them to attain a more natural conformation. Based on the results, the proposed workflow in this paper could therefore potentially contribute to aid in risk assessment of mAb candidates in early development.

6

Zakaria, Philip, Greg W. Dicinoski, Boon Khing Ng, Robert A. Shellie, Melissa Hanna-Brown, and Paul R. Haddad. "Application of retention modelling to the simulation of separation of organic anions in suppressed ion chromatography." Journal of Chromatography A 1216, no. 38 (September 2009): 6600–6610. http://dx.doi.org/10.1016/j.chroma.2009.07.051.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Dünnebier, G., and K. U. Klatt. "Modelling and simulation of nonlinear chromatographic separation processes: a comparison of different modelling approaches." Chemical Engineering Science 55, no. 2 (January 2000): 373–80. http://dx.doi.org/10.1016/s0009-2509(99)00332-2.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Adeyemo, M. A., O. Adeyeye, O. A. Okeniyi, and S. O. Idowu. "Biomembrane Modelling in Planar Chromatographic Determination of Lipophilicity Using Olive and Castor Oils." Nigerian Journal of Pharmaceutical Research 16, no. 2 (January 19, 2021): 97–106. http://dx.doi.org/10.4314/njpr.v16i2.1.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

BackgroundLipophilicity is a crucial physicochemical parameter that predicts in vivo pharmacokinetics and should be reliably estimated in early stage drug discovery to reduce incidence of attrition. Previous methodologies for its measurement often lead to technically incorrect decisions due to simplistic architecture and poor biomimetic attributes. Significantly, a certain seed oil, used for biomembrane modelling on planar chromatographic platform, was reported to be sufficiently biomimetic and fit for purpose.ObjectivesTo evaluate olive oil (OL) and olive-castor oil (OL-C) equi-mixture as lipids for biomembrane simulation on planar chromatographic platform.Material and MethodRetention behavior of nabumetone, a model compound was used to optimize these potential lipid membranes using a thin film engineered from 5% Liquid paraffin (LP) as benchmark, while halofantrine, nabumetone , α-naphthol and β-naphthol representing varying molecular polarities, were used for validation studies. The validation involved 2-way analysis of variance (ANOVA) associated with variability in Basic lipophilicity parameter (Rmw), and Specific hydrophobic surface area (SHSA) for the optimized surfaces, relative to LP and octadecylsilane (ODS) Further validation entailed correlation of the lipophilicity descriptor i.e. isocratic chromatographic hydrophobicity index (ICHI) on OL, OL-C, ODS and LP with experimental Log P(octanol/water).ResultsOptimized film thicknesses were produced by 5% OL and 1.25% OL-C (p > 0.05). The 2-way ANOVA revealed great variability in performance characteristics of the surfaces (p < 0.0001), and the new surfaces also gave poorer correlation with Log P values (R2= 0.502 and 0.449 respectively).ConclusionThe 1.25 % OL-C demonstrated a higher biomimetic attribute and warrants further validation studies to ascertain biorelevance, of lipophilicity measurement on this platform, in predicting oral drug absorption. Keywords: Lipophilicity, Reversed-phase Thin Layer Chromatography, Retention behaviour, Olive oil, Castor oil

9

Bourdarias, Christian, Marguerite Gisclon, and Stéphane Junca. "Kinetic formulation of a 2 × 2 hyperbolic system arising in gas chromatography." Kinetic & Related Models 13, no. 5 (2020): 869–88. http://dx.doi.org/10.3934/krm.2020030.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Câmara, Leôncio Diógenes T., and Antônio J. Silva Neto. "Network modeling of chromatography by stochastic phenomena of adsorption, diffusion and convection." Applied Mathematical Modelling 33, no. 5 (May 2009): 2491–501. http://dx.doi.org/10.1016/j.apm.2008.07.013.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Liu, Shuting, Xianwen Gao, Wenhai Qi, and Shumei Zhang. "Soft sensor modelling of propylene conversion based on a Takagi-Sugeno fuzzy neural network optimized with independent component analysis and mutual information." Transactions of the Institute of Measurement and Control 41, no. 3 (May 24, 2018): 737–48. http://dx.doi.org/10.1177/0142331218770498.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Propylene conversion is important to economic efficiency in the production of acrylic acid. Hence, the online measurement of propylene conversion is becoming more and more important. The current measurement method is mainly uses an offline meteorological chromatography analyser, which is difficult to measure accurately in real time. A soft sensor modelling method of propylene conversion based on Takagi-Sugeno (T-S) fuzzy neural network optimized by independent component analysis and mutual information is proposed in this paper. Firstly, fast independent component analysis-based denoising strategy is developed to remove the noise in the measurement of variables influenced by propylene conversion. Then, a mutual information-based variable selection method is proposed to select the key variables from multitudinous variables to reduce the influence of weak correlation. Finally, a T-S fuzzy neural network algorithm is employed to forecast the propylene conversion in the process of propylene oxidation. Simulation results show that the proposed soft sensor modelling method has better prediction accuracy and generalization ability. The method of this paper is obvious and effective.

12

James, François, Mauricio Sepúlveda, and Patrick Valentin. "Statistical Thermodynamics Models for Multicomponent Isothermal Diphasic Equilibria." Mathematical Models and Methods in Applied Sciences 07, no. 01 (February 1997): 1–29. http://dx.doi.org/10.1142/s0218202597000025.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

We propose in this paper a whole family of models for isothermal diphasic equilibrium, which generalize the classical Langmuir isotherm. The main tool to obtain these models is a fine modeling of each phase, which states various constraints on the equilibrium. By writing down the Gibbs conditions of thermodynamical equilibrium for both phases, we are led to a constrained minimization problem, which is solved through the Lagrange multipliers. If one of the phases is an ideal solution, we can solve explicitly the equations, and obtain an analytic model. In the most general case, we have implicit formulas, and the models are computed numerically. The models of multicomponent isotherm we obtain in this paper are designed for chromatography, but can be adapted mutatis mutandis to other cases.

13

Brillard, A. "Flow modelling of chemical species through a chromatographic column." Mathematical and Computer Modelling 41, no. 11-12 (May 2005): 1237–50. http://dx.doi.org/10.1016/j.mcm.2004.09.005.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Castéran, Fanny, Karim Delage, Nicolas Hascoët, Amine Ammar, Francisco Chinesta, and Philippe Cassagnau. "Data-Driven Modelling of Polyethylene Recycling under High-Temperature Extrusion." Polymers 14, no. 4 (February 18, 2022): 800. http://dx.doi.org/10.3390/polym14040800.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Two main problems are studied in this article. The first one is the use of the extrusion process for controlled thermo-mechanical degradation of polyethylene for recycling applications. The second is the data-based modelling of such reactive extrusion processes. Polyethylenes (high density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE)) were extruded in a corotating twin-screw extruder under high temperatures (350 °C < T < 420 °C) for various process conditions (flow rate and screw rotation speed). These process conditions involved a decrease in the molecular weight due to degradation reactions. A numerical method based on the Carreau-Yasuda model was developed to predict the rheological behaviour (variation of the viscosity versus shear rate) from the in-line measurement of the die pressure. The results were successfully compared to the viscosity measured from offline measurement assuming the Cox-Merz law. Weight average molecular weights were estimated from the resulting zero-shear rate viscosity. Furthermore, the linear viscoelastic behaviours (Frequency dependence of the complex shear modulus) were also used to predict the molecular weight distributions of final products by an inverse rheological method. Size exclusion chromatography (SEC) was performed on five samples, and the resulting molecular weight distributions were compared to the values obtained with the two aforementioned techniques. The values of weight average molecular weights were similar for the three techniques. The complete molecular weight distributions obtained by inverse rheology were similar to the SEC ones for extruded HDPE samples, but some inaccuracies were observed for extruded UHMWPE samples. The Ludovic® (SC-Consultants, Saint-Etienne, France) corotating twin-screw extrusion simulation software was used as a classical process simulation. However, as the rheo-kinetic laws of this process were unknown, the software could not predict all the flow characteristics successfully. Finally, machine learning techniques, able to operate in the low-data limit, were tested to build predicting models of the process outputs and material characteristics. Support Vector Machine Regression (SVR) and sparsed Proper Generalized Decomposition (sPGD) techniques were chosen to predict the process outputs successfully. These methods were also applied to material characteristics data, and both were found to be effective in predicting molecular weights. More precisely, the sPGD gave better results than the SVR for the zero-shear viscosity prediction. Stochastic methods were also tested on some of the data and showed promising results.

15

Makrodimitris, Kosta, Erik J. Fernandez, Thomas B. Woolf, and John P. O'connell. "ALLD: An object-oriented mesoscopic simulation program for polar biomolecules in hydrophobic chromatography or biomembranes." Molecular Simulation 31, no. 9 (August 2005): 623–36. http://dx.doi.org/10.1080/08927020500108262.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Wang, Jingyu, Jian Yang, Long Li, Pei Qian, and Qiuwang Wang. "Numerical simulation and circuit network modelling of flow distributions in 2-D array configurations." Thermal Science 22, no. 5 (2018): 1987–98. http://dx.doi.org/10.2298/tsci171230256w.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Packing configuration is widely used in chemical industries such as chemical re-action and chromatograph where the flow distribution has a significant effect on the performance of heat and mass transfer. In the present paper, numerical simulation is carried out to investigate the fluid-flow in three 2-D array configurations including in-line array, staggered array and hexagonal array. Meanwhile, a simplified equivalent circuit network model based on the Voronoi tessellation is proposed to simulate the flow models. It is found that firstly, the local Reynolds number could be used as a criterion to determine the flow regime. Flow with maximum local Reynolds number less than 40 could be regarded as Darcy flow. Secondly, the flow pattern can be well represented by the network model in the range of Darcy flow with the determination method of hydraulic resistance pro-posed in the present paper.

17

Barkhordari, Ali, Saeed Karimian, Antonio Rodero, Dorota Anna Krawczyk, Seyed Iman Mirzaei, and Amir Falahat. "Carbon Dioxide Decomposition by a Parallel-Plate Plasma Reactor: Experiments and 2-D Modelling." Applied Sciences 11, no. 21 (October 27, 2021): 10047. http://dx.doi.org/10.3390/app112110047.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

The applicability of high voltage electrical discharges for the decomposition of CO2 has been extensively demonstrated. In this study, a new AC parallel-plate plasma reactor is presented which was designed for this purpose. Detailed experimental characterization and simulation of this reactor were performed. Gas chromatography of the exhaust gases enabled calculation of the CO2 conversion and energy efficiency. A conversion factor approximating 25% was obtained which is higher in comparison to existing plasma sources. Optical emission spectroscopy enabled the determination of the emission intensities of atoms and molecules inside the plasma and characterization of the discharge. The Stark broadening of the Balmer hydrogen line Hβ was used for the estimation of the electron density. The obtained densities were of the order of 5 × 1014 cm−3 which indicates that the electron kinetic energy dominated the discharge. The rotational, vibrational, and excitation temperatures were determined from the vibro-rotational band of the OH radical. A 2-temperature plasma was found where the estimated electron temperatures (~18,000 K) were higher than the gas temperatures (~2000 K). Finally, a 2-D model using the fluid equations was developed for determining the main processes in the CO2 splitting. The solution to this model, using the finite element method, gave the temporal and spatial behaviors of the formed species densities, the electric potential, and the temperatures of electrons.

18

Marquardt, Jan E., Carsten-Rene Arlt, Robin Trunk, Matthias Franzreb, and Mathias J. Krause. "Numerical and experimental examination of the retention of magnetic nanoparticles in magnetic chromatography." Computers & Mathematics with Applications 89 (May 2021): 34–43. http://dx.doi.org/10.1016/j.camwa.2021.02.010.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Schmölder, Johannes, and Malte Kaspereit. "A Modular Framework for the Modelling and Optimization of Advanced Chromatographic Processes." Processes 8, no. 1 (January 3, 2020): 65. http://dx.doi.org/10.3390/pr8010065.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

A framework is introduced for the systematic development of preparative chromatographic processes. It is intended for the optimal design of conventional and advanced concepts that exploit strategies, such as recycling, side streams, bypasses, using single or multiple columns, and combinations thereof. The Python-based platform simplifies the implementation of new processes and design problems by decoupling design tasks into individual modules for modelling, simulation, assertion of cyclic stationarity, product fractionation, and optimization. Interfaces to external libraries provide flexibility regarding the choice of column model, solver, and optimizer. The current implementation, named CADET-Process, uses the software CADET for solving the model equations. The structure of the framework is discussed and its application for optimal design of existing and identification of new chromatographic operating concepts is demonstrated by case studies.

20

Dünnebier, G., I. Weirich, and K. U. Klatt. "Computationally efficient dynamic modelling and simulation of simulated moving bed chromatographic processes with linear isotherms." Chemical Engineering Science 53, no. 14 (July 1998): 2537–46. http://dx.doi.org/10.1016/s0009-2509(98)00076-1.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Ganetsos, G., and PE Barker. "The mathematical modelling and computer simulation of chromatographic systems used in chemical and biochemical applications." Mathematical and Computer Modelling 14 (1990): 1052–56. http://dx.doi.org/10.1016/0895-7177(90)90337-m.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Lin, Chen-Jiann, Tseng-Hsiang Tse, Liu-Cheng Che, and Liang-Ming Tsai. "Computer aided design and analysis on distributors in DAC columns." MATEC Web of Conferences 185 (2018): 00024. http://dx.doi.org/10.1051/matecconf/201818500024.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Dynamic axial compression (DAC) columns are key elements in simulated moving bed, which is a chromatography process in drug industry and chemical engineering. In this study, rules for designing distributors are proposed based on mass conservation and validated by experiments, the computer aided design (CAD) and the computational fluid dynamics (CFD). Experimental works are conducted to choose feasible numerical parameters for simulations. In CFD, the transient laminar flow fields are governed by the momentum and species transport equations with Darcy's law to model the porous zone in the packed bed. Results show that CFD combined with CAD solid modelling is a good approach to explore detailed flow fields in DAC columns and carry out parameter analysis for innovative designs. For further testing and evaluation, a new model of compound distributor is designed, 3D printed and processed in factory for practical applications in preparative chromatography.

23

Sun, Mingshuai, Fumin Wang, Wei Liu, Wangfeng Cai, and Xubin Zhang. "Novel application of gas chromatography in measurement of gas flow rate." Flow Measurement and Instrumentation 50 (August 2016): 245–51. http://dx.doi.org/10.1016/j.flowmeasinst.2016.07.006.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Abbasi, Yasser, Chris M. Mannaerts, and William Makau. "Modeling Pesticide and Sediment Transport in the Malewa River Basin (Kenya) Using SWAT." Water 11, no. 1 (January 7, 2019): 87. http://dx.doi.org/10.3390/w11010087.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Understanding the dynamics of pesticide transport in the Malewa River and Lake Naivasha, a major fresh water resource, is critical to safeguard water quality in the basin. In this study, the soil and water assessment tool (SWAT) model was used to simulate the discharge of sediment and pesticides (notably the organochlorine residues of lindane, methoxychlor and endosulfan) into the Malewa River Basin. Model sensitivity analysis, calibration and validation were performed for both daily and monthly time steps using the sequential uncertainty fitting version 2 (SUFI-2) algorithm of the SWAT-CUP tool. Water level gauge data as well as a digital turbidity sensor (DTS-12) for suspended sediment transport were used for the SWAT calibration. Pesticide residues were measured at Upper and Down Malewa locations using a passive sampling technique and their quantity was determined using laboratory gas chromatography. The sensitivity analysis results showed that curve number (CN2), universal soil loss equation erodibility factor (USLE-K) and pesticide application efficiency (AP_EF) formed the most sensitive parameters for discharge, sediment and pesticide simulations, respectively. In addition, SWAT model calibration and validation showed better results for monthly discharge simulations than for daily discharge simulations. Similarly, the results obtained for the monthly sediment calibration demonstrated more match between measured and simulated data as compared to the simulation at daily steps. Comparison between the simulated and measured pesticide concentrations at upper Malewa and down Malewa locations demonstrated that although the model mostly overestimated pesticide loadings, there was a positive association between the pesticide measurements and the simulations. Higher concentrations of pesticides were found between May and mid-July. The similarity between measured and simulated pesticides shows the potential of the SWAT model as initial evaluation modelling tool for upstream to downstream suspended sediment and pesticide transport in catchments.

25

Hedayati, Ali, and S. M. Ghoreishi. "Artificial Neural Network and Adaptive Neuro-Fuzzy Interface System Modeling of Supercritical CO2 Extraction of Glycyrrhizic Acid from Glycyrrhiza glabra L." Chemical Product and Process Modeling 11, no. 3 (September 1, 2016): 217–30. http://dx.doi.org/10.1515/cppm-2015-0048.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Abstract In this study, the extraction of Glycyrrhizic acid (GA) from Glycyrrhiza glabra (licorice) root was investigated by Soxhlet extraction and modified supercritical CO2 with water as co-solvents and 30 min of static extraction time. The high performance liquid chromatography (HPLC) was used to identify and quantitatively determine the amount of extracted GA recovery of supercritical CO2 extraction of GA. The extraction recovery was modeled by adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN). Different ANFIS networks (by changing the type of membership functions) were compared with evaluation of networks accuracy in GA recovery prediction and subsequently the suitable network was determined. A three-layer artificial neural network was also developed for modeling of GA extraction from licorice plant root. In this regard, different networks (by changing the number of neurons in the hidden layer and algorithm of network training) were compared with evaluation of networks accuracy in extraction recovery prediction. One-step secant back propagation algorithm with six neurons in hidden layer was found to be the most suitable network and the coefficient of determination (R2) was 98.5 %. Gaussian combination membership function (gauss2mf) using 2 membership function to each input was obtained to be optimum ANFIS architecture with mean square error (MSE) of 0.05,0.17 and 0.07 for training, testing and checking data, respectively.

26

Giordano, Deborah, Angelo Facchiano, Paola Minasi, Nunzio D’Agostino, Mario Parisi, and Virginia Carbone. "Phenolic Compounds and Capsaicinoids in Three Capsicum annuum Varieties: From Analytical Characterization to In Silico Hypotheses on Biological Activity." Molecules 28, no. 19 (September 22, 2023): 6772. http://dx.doi.org/10.3390/molecules28196772.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

The affinity of specific phenolic compounds (PCs) and capsaicinoids (CAPs) present in three Capsicum annuum varieties (Friariello, Cayenne and Dzuljunska Sipka) to the transient receptor potential vanilloid member 1 (TRPV1) was investigated by integrating an analytic approach for the simultaneous extraction and analysis through high-performance liquid chromatography coupled with ion trap mass spectrometry (HPLC/ITMS) and UV detection (HPLC-UV) of PCs and CAPs and structural bioinformatics based on the protein modelling and molecular simulations of protein–ligand docking. Overall, a total of 35 compounds were identified in the different samples and CAPs were quantified. The highest content of total polyphenols was recorded in the pungent Dzuljunska Sipka variety (8.91 ± 0.05 gGAE/Kg DW) while the lowest was found in the non-pungent variety Friariello (3.58 ± 0.02 gGAE/Kg DW). Protein modelling generated for the first time a complete model of the homotetrameric human TRPV1, and it was used for docking simulations with the compounds detected via the analytic approach, as well as with other compounds, as an inhibitor reference. The simulations indicate that different capsaicinoids can interact with the receptor, providing details on the molecular interaction, with similar predicted binding energy values. These results offer new insights into the interaction of capsaicinoids with TRPV1 and their possible actions.

27

Cooper, Isabelle, Cornelia B. Landersdorfer, Ashley Gordon St John, and Andis Graudins. "The pharmacokinetics of intranasal droperidol in volunteers characterised via population modelling." SAGE Open Medicine 6 (January 2018): 205031211881328. http://dx.doi.org/10.1177/2050312118813283.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Background: Droperidol is used parenterally to treat nausea and vomiting, migraine and acute behavioural disturbance. Intranasal use is not reported for droperidol. Intranasal drug administration reduces need for intravenous line placement and risk of needle-stick. Objective: To model population pharmacokinetics of intranasal droperidol. Method: Single doses of intranasal and intravenous droperidol (0.02 mg/kg) were studied in an open-label crossover-trial in seven volunteers with a 1-week washout period. Blood samples collected over 10-h were analysed by liquid chromatography tandem mass spectrometer. Droperidol plasma concentrations following intravenous and intranasal administration were subjected to non-compartmental analysis and population pharmacokinetic modelling using S-ADAPT. Monte Carlo simulations were conducted for various potential intranasal dosage regimens. Results: The droperidol concentration-time profiles following intravenous and intranasal administration were best described by a model with two equilibrating disposition compartments and linear elimination. The apparent elimination clearance for intranasal dosing was 87.9 L/h and apparent central volume of distribution 18.2 L. Monte Carlo simulations of 5 mg droperidol (corresponding to the maximum volume that can be practically administered intranasal at a time) given intranasally at 0 and 5 min or 0 and 10 min indicated peak concentrations would reach those seen at 25 min after single intravenous administration of 1.5 mg. No adverse clinical effects or QT interval prolongation were observed. Conclusion: Given the reduced bioavailability of intranasal droperidol, Monte Carlo simulations suggested that it could potentially be used at a higher dose (2.5–5 mg) than currently used intravenously in clinical trials assessing the effectiveness in treatment of nausea, vomiting and migraine.

28

Zhang, Lin, Guofeng Zhao, and Yan Sun. "Molecular dynamics simulation and experimental validation of the effect of pH on protein desorption in hydrophobic charge induction chromatography." Molecular Simulation 36, no. 13 (November 2010): 1096–103. http://dx.doi.org/10.1080/08927022.2010.506511.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Curró, C., D. Fusco, and N. Manganaro. "Exact description of simple wave interactions in multicomponent chromatography." Journal of Physics A: Mathematical and Theoretical 48, no. 1 (December 4, 2014): 015201. http://dx.doi.org/10.1088/1751-8113/48/1/015201.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Klatt, Karsten-Ulrich, Guido Dünnebier, and Sebastian Engell. "Modeling and computationally efficient simulation of chromatographic separation processes." Mathematics and Computers in Simulation 53, no. 4-6 (October 2000): 449–55. http://dx.doi.org/10.1016/s0378-4754(00)00240-8.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Zhu, Huaiqin, Peijun Ji, and Wei Feng. "Explanation of enantioseparation of amino acid derivatives in gas chromatography." Molecular Simulation 37, no. 15 (December 2011): 1258–65. http://dx.doi.org/10.1080/08927022.2011.597393.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Khan, Shumaila, Sabahuddin Ahmad, Mohammad Imran Siddiqi, and Bilqees Bano. "Physico-chemical and in-silico analysis of a phytocystatin purified from Brassica juncea cultivar RoAgro 5444." Biochemistry and Cell Biology 94, no. 6 (December 2016): 584–96. http://dx.doi.org/10.1139/bcb-2016-0029.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

This study describes the isolation and purification of a phytocystatin from seeds of Brassica juncea (Indian mustard; cultivar RoAgro 5444), which is an important oilseed crop both agriculturally and economically. The protein was purified by gel filtration chromatography with 24.3% yield and 204-fold purification, and visualised by 2D gel electrophoresis. The 18.1 kDa mustard cystatin was highly specific for cysteine proteinases. The plant cystatin inhibited cathepsin B, confirming its role in conferring pest resistance. The inhibitor was highly stable over a pH range of 3–10 and retained significant inhibitory potential up to 70 °C. The stoichiometry of its interaction with papain, determined by isothermal calorimetry, suggests a 1:1 complex. Secondary structural elements calculated by far-UV circular dichroism (CD) spectroscopy show an 18.8% α-helical and 21% β-sheet structure. The protein was a non-competitive inhibitor of thiol proteinases. The Stokes radius and frictional co-efficient were used to describe the shape and size of the protein. Homology modelling and docking studies proposed a prototype illustrating the Brassica phytocystatin mediated papain inhibition. Molecular dynamics (MD) study revealed the excellent stability of the papain–phytocystatin complex during a simulation for 100 ns. Detailed results identify the mustard cystatin as an important member of the phytocystatin family.

33

Bellich, Barbara, Ining A. Jou, Marco Caterino, Roberto Rizzo, Neil Ravenscroft, Mustafa Fazli, Tim Tolker-Nielsen, John W. Brady, and Paola Cescutti. "Burkholderia cenocepacia H111 Produces a Water-Insoluble Exopolysaccharide in Biofilm: Structural Determination and Molecular Modelling." International Journal of Molecular Sciences 21, no. 5 (March 2, 2020): 1702. http://dx.doi.org/10.3390/ijms21051702.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Biofilms are a multicellular way of life, where bacterial cells are close together and embedded in a hydrated macromolecular matrix which offers a number of advantages to the cells. Extracellular polysaccharides play an important role in matrix setup and maintenance. A water-insoluble polysaccharide was isolated and purified from the biofilm produced by Burkholderia cenocepacia strain H111, a cystic fibrosis pathogen. Its composition and glycosidic linkages were determined using Gas–Liquid Chromatography–Mass Spectrometry (GLC–MS) on appropriate carbohydrate derivatives while its complete structure was unraveled by 1D and 2D NMR spectroscopy in deuterated sodium hydroxide (NaOD) aqueous solutions. All the collected data demonstrated the following repeating unit for the water-insoluble B. cenocepacia biofilm polysaccharide: [3)-α-d-Galp-(1→3)-α-d-Glcp-(1→3)-α-d-Galp-(1→3)-α-d-Manp-(1→]n Molecular modelling was used, coupled with NMR Nuclear Overhauser Effect (NOE) data, to obtain information about local structural motifs which could give hints about the polysaccharide insolubility. Both modelling and NMR data pointed at restricted dynamics of local conformations which were ascribed to the presence of inter-residue hydrogen bonds and to steric restrictions. In addition, the good correlation between NOE data and calculated interatomic distances by molecular dynamics simulations validated potential energy functions used for calculations.

34

Gosse, Laurent. "Time-Splitting Schemes and Measure Source Terms for a Quasilinear Relaxing System." Mathematical Models and Methods in Applied Sciences 13, no. 08 (August 2003): 1081–101. http://dx.doi.org/10.1142/s0218202503002829.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Several singular limits are investigated in the context of a 2 × 2 system arising for instance in the modeling of chromatographic processes. In particular, we focus on the case where the relaxation term and a L2 projection operator are concentrated on a discrete lattice by means of Dirac measures. This formulation allows one to study more easily some time-splitting numerical schemes.

35

Budiman, Cahyo, Raimalynah Abd Razak, Angelesa Runin Anak Unggit, Rafida Razali, Meiny Suzery, Ruzaidi Azli Mohd Mokhtar, Ping-Chin Lee та Didik Huswo Utomo. "Catalytic Properties of Caseinolytic Protease Subunit of Plasmodium knowlesi and Its Inhibition by a Member of δ-Lactone, Hyptolide". Molecules 27, № 12 (12 червня 2022): 3787. http://dx.doi.org/10.3390/molecules27123787.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

The caseinolytic protease (Clp) system plays an essential role in the protein homeostasis of the malaria parasite, particularly at the stage of apicoplast development. The inhibition of this protein is known to have a lethal effect on the parasite and is therefore considered an interesting avenue for antimalaria drugs discovery. The catalytic activity of the Clp system is modulated by its proteolytic subunit (ClpP), which belongs to the serine protease family member and is therefore extensively studied for further inhibitors development. Among many inhibitors, the group of β-lactone is known to be a specific inhibitor for ClpP. Nevertheless, other groups of lactones have never been studied. This study aims to characterize the catalytic properties of ClpP of Plasmodium knowlesi (Pk-ClpP) and the inhibition properties of a δ-lactone hyptolide against this protein. Accordingly, a codon-optimized synthetic gene encoding Pk-ClpP was expressed in Escherichia coli BL21(DE3) and purified under a single step of Ni2+-affinity chromatography, yielding a 2.20 mg from 1 L culture. Meanwhile, size-exclusion chromatography indicated that Pk-ClpP migrated primarily as homoheptameric with a size of 205 kDa. The specific activity of pure Pk-ClpP was 0.73 U µg−1, with a catalytic efficiency kcat/KM of 0.05 µM−1 s−1, with optimum temperature and pH of 50 °C and 7.0–7.5, respectively. Interestingly, hyptolide, a member of δ-lactone, was shown to inhibit Pk-ClpP with an IC50 value of 17.36 ± 1.44 nM. Structural homology modelling, secondary structure prediction, and far-UV CD spectra revealed that helical structures dominate this protein. In addition, the structural homology modeling showed that this protein forms a barrel-shaped homoheptamer. Docking simulation revealed that the inhibition was found to be a competitive inhibition in which hyptolide was able to dock into the catalytic site and block the substrate. The competitiveness of hyptolide is due to the higher binding affinity of this molecule than the substrate.

36

Alamir, Mazen, Fadi Ibrahim, and Jean Pierre Corriou. "A flexible nonlinear model predictive control scheme for quality/performance handling in nonlinear SMB chromatography." Journal of Process Control 16, no. 4 (April 2006): 333–44. http://dx.doi.org/10.1016/j.jprocont.2005.07.001.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Brini, Alberto, Vahe Avagyan, Ric C. H. de Vos, Jack H. Vossen, Edwin R. van den Heuvel, and Jasper Engel. "Improved One-Class Modeling of High-Dimensional Metabolomics Data via Eigenvalue-Shrinkage." Metabolites 11, no. 4 (April 13, 2021): 237. http://dx.doi.org/10.3390/metabo11040237.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

One-class modelling is a useful approach in metabolomics for the untargeted detection of abnormal metabolite profiles, when information from a set of reference observations is available to model “normal” or baseline metabolite profiles. Such outlying profiles are typically identified by comparing the distance between an observation and the reference class to a critical limit. Often, multivariate distance measures such as the Mahalanobis distance (MD) or principal component-based measures are used. These approaches, however, are either not applicable to untargeted metabolomics data, or their results are unreliable. In this paper, five distance measures for one-class modeling in untargeted metabolites are proposed. They are based on a combination of the MD and five so-called eigenvalue-shrinkage estimators of the covariance matrix of the reference class. A simple cross-validation procedure is proposed to set the critical limit for outlier detection. Simulation studies are used to identify which distance measure provides the best performance for one-class modeling, in terms of type I error and power to identify abnormal metabolite profiles. Empirical evidence demonstrates that this method has better type I error (false positive rate) and improved outlier detection power than the standard (principal component-based) one-class models. The method is illustrated by its application to liquid chromatography coupled to mass spectrometry (LC-MS) and nuclear magnetic response spectroscopy (NMR) untargeted metabolomics data from two studies on food safety assessment and diagnosis of rare diseases, respectively.

38

Rossignol, S., L. Chiappini, E. Perraudin, C. Rio, S. Fable, R. Valorso, and J. F. Doussin. "Development of parallel sampling and analysis for the elucidation of gas/particle partitioning of oxygenated semi-volatile organics: a limonene ozonolysis study." Atmospheric Measurement Techniques Discussions 5, no. 1 (February 6, 2012): 1153–231. http://dx.doi.org/10.5194/amtd-5-1153-2012.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Abstract. Gas/particle partitioning behaviour of secondary organic matter semi-volatile fraction and the associated multiphase chemistry are key features to accurately evaluate secondary organic aerosol climate and health impacts. However, today, oxygenated secondary species partitioning is rarely assessed in experimental SOA studies and SOA modelling is still largely based on estimated partitioning data. This paper describes a new analytical approach, solvent free and easy to use, to explore the chemical composition of the secondary organic matter at a molecular scale in both gas and particulate phases. The method is based on thermal-desorption (TD) of gas and particulate samples, coupled with gas chromatography (GC) and mass spectrometry (MS), with on sampling supports derivatisation processes. Gaseous compounds are trapped on PFBHA or MTBSTFA pre-coated Tenax TA adsorbent tubes. Particulate samples are collected onto quartz or Teflon-quartz filters and subsequently exposed to PFBHA or MTBSTFA derivatisation reagents before TD-GC-MS analysis. Method development and validation are presented from an atmospherically relevant range of organic acids and carbonyl and hydroxyl compounds. Method application to a limonene ozonolysis experiment conducted in the EUPHORE simulation chamber under close-to-real conditions of low concentrations and relative humidity provides an overview of the method abilities. 25 compounds have been positively or tentatively identified, 9 being in both gaseous and particulate phases and 11, among them tri carboxylic acids, hydroxyl dicarboxylic acids and oxodicarboxylic acids, being detected for the first time.

39

Wilhelms, Benedikt, Jens Broscheit, and Sergey Shityakov. "Chemical Analysis and Molecular Modelling of Cyclodextrin-Formulated Propofol and Its Sodium Salt to Improve Drug Solubility, Stability and Pharmacokinetics (Cytogenotoxicity)." Pharmaceuticals 16, no. 5 (April 28, 2023): 667. http://dx.doi.org/10.3390/ph16050667.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Propofol is a widely used general anesthetic in clinical practice, but its use is limited by its water-insoluble nature and associated pharmacokinetic and pharmacodynamic limitations. Therefore, researchers have been searching for alternative formulations to lipid emulsion to address the remaining side effects. In this study, novel formulations for propofol and its sodium salt Na-propofolat were designed and tested using the amphiphilic cyclodextrin (CD) derivative hydroxypropyl-β-cyclodextrin (HPβCD). The study found that spectroscopic and calorimetric measurements suggested complex formation between propofol/Na-propofolate and HPβCD, which was confirmed by the absence of an evaporation peak and different glass transition temperatures. Moreover, the formulated compounds showed no cytotoxicity and genotoxicity compared to the reference. The molecular modeling simulations based on molecular docking predicted a higher affinity for propofol/HPβCD than for Na-propofolate/HPβCD, as the former complex was more stable. This finding was further confirmed by high-performance liquid chromatography. In conclusion, the CD-based formulations of propofol and its sodium salt may be a promising option and a plausible alternative to conventional lipid emulsions.

40

Rossignol, S., L. Chiappini, E. Perraudin, C. Rio, S. Fable, R. Valorso, and J. F. Doussin. "Development of a parallel sampling and analysis method for the elucidation of gas/particle partitioning of oxygenated semi-volatile organics: a limonene ozonolysis study." Atmospheric Measurement Techniques 5, no. 6 (June 27, 2012): 1459–89. http://dx.doi.org/10.5194/amt-5-1459-2012.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Abstract. The gas/particle partitioning behaviour of the semi-volatile fraction of secondary organic matter and the associated multiphase chemistry are key features to accurately evaluate climate and health impacts of secondary organic aerosol (SOA). However, today, the partitioning of oxygenated secondary species is rarely assessed in experimental SOA studies and SOA modelling is still largely based on estimated partitioning data. This paper describes a new analytical approach, solvent-free and easy to use, to explore the chemical composition of the secondary organic matter at a molecular scale in both gas and particulate phases. The method is based on thermal desorption (TD) of gas and particulate samples, coupled with gas chromatography (GC) and mass spectrometry (MS), with derivatisation on sampling supports. Gaseous compounds were trapped on Tenax TA adsorbent tubes pre-coated with pentafluorobenzylhydroxylamine (PFBHA) or N-Methyl-N-(t-butyldimethylsilyl)trifluoroacetamide (MTBSTFA). Particulate samples were collected onto quartz or Teflon-quartz filters and subsequently subjected to derivatisation with PFBHA or MTBSTFA before TD-GC/MS analysis. Method development and validation are presented for an atmospherically relevant range of organic acids and carbonyl and hydroxyl compounds. Application of the method to a limonene ozonolysis experiment conducted in the EUPHORE simulation chamber under simulated atmospheric conditions of low concentrations of limonene precursor and relative humidity, provides an overview of the method capabilities. Twenty-five compounds were positively or tentatively identified, nine being in both gaseous and particulate phases; and twelve, among them tricarboxylic acids, hydroxyl dicarboxylic acids and oxodicarboxylic acids, being detected for the first time.

41

Zobel-Roos, Steffen, Mourad Mouellef, Reinhard Ditz, and Jochen Strube. "Distinct and Quantitative Validation Method for Predictive Process Modelling in Preparative Chromatography of Synthetic and Bio-Based Feed Mixtures Following a Quality-by-Design (QbD) Approach." Processes 7, no. 9 (September 2, 2019): 580. http://dx.doi.org/10.3390/pr7090580.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Process development, especially in regulated industries, where quality-by-design approaches have become a prerequisite, is cost intensive and time consuming. A main factor is the large number of experiments needed. Process modelling can reduce this number significantly by replacing experiments with simulations. However, this requires a validated model. In this paper, a process and model development workflow is presented, which focuses on implementing, parameterizing, and validating the model in four steps. The presented methods are laid out to gain, create, or generate the maximum information and process knowledge needed for successful process development. This includes design of experiments and statistical evaluations showing process robustness, sensitivity of target values to process parameters, and correlations between process and target values. Two case studies are presented. An ion exchange capture step for monoclonal antibodies focusing on high accuracy and low feed consumption; and one case study for small molecules focusing on rapid process development, emphasizing speed of parameter determination.

42

Leven, Cyril, Sacha Schutz, Marie-Pierre Audrezet, Emmanuel Nowak, Laurent Meijer, and Tristan Montier. "Non-Linear Pharmacokinetics of Oral Roscovitine (Seliciclib) in Cystic Fibrosis Patients Chronically Infected with Pseudomonas aeruginosa: A Study on Population Pharmacokinetics with Monte Carlo Simulations." Pharmaceutics 12, no. 11 (November 12, 2020): 1087. http://dx.doi.org/10.3390/pharmaceutics12111087.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Roscovitine (Seliciclib), a new protein kinase inhibitor, was administered orally to adult patients with cystic fibrosis for the first time in the ROSCO-CF trial, a dose-escalation, phase IIa, randomized, controlled trial. Extensive pharmacokinetic sampling was performed up to 12 h after the first oral dose. Roscovitine and its main metabolite M3 were quantified by liquid chromatography coupled with tandem mass spectrometry. The pharmacokinetics analyses were performed by non-linear mixed effects modelling. Monte Carlo simulations were performed to assess the impact of dose on the pharmacokinetics of oral roscovitine. Twenty-three patients received oral doses ranging from 200 to 800 mg of roscovitine and 138 data points were available for both roscovitine and M3 concentrations. The pharmacokinetics was best described by a two-compartment parent-metabolite model, with a complex saturable absorption process modelled as the sum of Gaussian inverse density functions. The Monte Carlo simulations showed a dose-dependent and saturable first-pass effect leading to pre-systemic formation of M3. The treatment with proton-pump inhibitors reduced the rate of absorption of oral roscovitine. The pharmacokinetics of oral roscovitine in adult patients with cystic fibrosis was non-linear and showed significant inter-individual variability. A repeat-dose study will be required to assess the inter-occasional variability of its pharmacokinetics.

43

Marton, Michal, Ján Ilavský, and Danka Barloková. "Pesticide removal and efficiency of different types of granular activated carbon." Pollack Periodica 16, no. 1 (March 25, 2021): 126–31. http://dx.doi.org/10.1556/606.2020.00140.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

AbstractPesticides as one of the micro-pollutants present a great problem and threat to the environment and human health. They can infiltrate the sources of drinking water by application on the agricultural fields. This article is focused on Atrazine, Terbuthylazine and their metabolites. It is their complex structure that makes them hard to degrade naturally and, thus, water needs to be treated before safe using. Therefore, this article studies adsorption on the two granular activated carbons Filtrasorb 400 and Norit 1240 W. For the determination of the concentration liquid chromatography was used. In this article it is presented that Filtrasorb 400 efficiency (26–40% and 33–45% for atrazine and terbuthylazine respectively) is better than the efficiency of Norit 1240 W (9–27% and 10–24% for atrazine and terbuthylazine respectively).

44

Thomas, M. P., C. Verma, S. M. Boyd, and K. Brocklehurst. "The structural origins of the unusual specificities observed in the isolation of chymopapain M and actinidin by covalent chromatography and the lack of inhibition of chymopapain M by cystatin." Biochemical Journal 306, no. 1 (February 15, 1995): 39–46. http://dx.doi.org/10.1042/bj3060039.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

1. The selectivity observed when the potentially general technique for the isolation of fully active forms of cysteine proteinases, covalent chromatography by thiol-disulphide interchange, is applied to chymopapain M and to actinidin was investigated by a combination of experimentation and computer modelling. Neither of these enzymes is able to react with the original Sepharose-GSH-2-dipyridyl disulphide gel, but fully active forms of both enzymes are obtained by using Sepharose-2-hydroxypropyl-2′-dipyridyl disulphide gel, which is both electrically neutral and sterically less demanding than the GSH gel. Electrostatic potential calculations, minimization and molecular-dynamics simulations provide explanations for the unusual, but different, specificities exhibited by actinidin and chymopapain M in the interactions of their active centres with ligands. 2. The unique behaviour of chymopapain M in exerting an almost absolute specificity for substrates with glycine at the P1 position and in resisting inhibition by cystatin was examined by the computer-modelling techniques. A new, modelled, structure of the complete chicken egg-white cystatin molecule based on the crystal structure of a short form of cystatin was deduced as a necessary prerequisite. The results suggest that electrostatic repulsion prevents reaction of actinidin with the GSH gel, whereas a steric ‘cap’ resulting from a unique arginine-65-glutamic acid-23 interaction in chymopapain M prevents reaction of the gel with this enzyme and accounts for the lack of its inhibition by cystatin and its specificity in catalysis. 3. Use of chymopapain M as a structural variant of papain demonstrates the validity of the predictions of Lowe and Yuthavong [Biochem. J. (1971) 124, 107-115] relating to the structural requirements and binding characteristics of the S1 subsite of papain.

45

Moreira, Bruno, António Sousa, Ana Maria Mendonça, and Aurélio Campilho. "Automatic Lane Segmentation in TLC Images Using the Continuous Wavelet Transform." Computational and Mathematical Methods in Medicine 2013 (2013): 1–19. http://dx.doi.org/10.1155/2013/218415.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

This paper describes a new methodology for lane detection in Thin-Layer Chromatography images. An approach based on the continuous wavelet transform is used to enhance the relevant lane information contained in the intensity profile obtained from image data projection. Lane detection proceeds in three phases: the first obtains a set of candidate lanes, which are validated or removed in the second phase; in the third phase, lane limits are calculated, and subtle lanes are recovered. The superior performance of the new solution was confirmed by a comparison with three other methodologies previously described in the literature.

46

Vargas-Bustamante, Jaquebet, Roberto Salcedo, and Jorge Balmaseda. "A Route to Understanding the Ethane Adsorption Selectivity of the Zeolitic Imidazolate Framework-8 in Ethane–Ethylene Mixtures." Materials 16, no. 19 (October 7, 2023): 6587. http://dx.doi.org/10.3390/ma16196587.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Ethylene production has a negative environmental impact, with its separation step being one of the major contributors of pollution. This has encouraged the search for energy-efficient alternatives, among which the adsorptive separation of ethane and ethylene stands out. ZIF-8 is a molecular sieve that is potentially useful for this purpose. It is selective to ethane, an exceptional property that remains unexplained. Furthermore, the adsorption of ethane and ethylene above room temperature, such as at steam cracking process outlet temperatures, has not been addressed either. This work aims to fill this knowledge gap by combining experiments at very low volumetric fillings with density–functional theory modelling methods. Adsorption isotherms of ethane and ethylene on ZIF-8 at pressures below 0.3 bar and 311 K, 333 K, and 363 K were measured using zero-length column chromatography. The low-pressure domain of the isotherms contains information on the interactions between the adsorbate molecules and the adsorbent. This favors the understanding of their macroscopic behavior from simulations at the atomic level. The isosteric enthalpy of adsorption of ethane remained constant at approximately −10 kJ/mol. In contrast, the isosteric enthalpy of adsorption of ethylene decreased from −4 kJ/mol to values akin to those of ethane as temperature increased. ZIF-8 selectivity to ethane, estimated from ideal adsorbed solution theory, decreased from 2.8 to 2.0 with increasing pressure up to 0.19 bar. Quantum mechanical modelling suggested that ethylene had minimal interactions with ZIF-8, while ethane formed hydrogen bonds with nitrogen atoms within its structure. The findings of this research are a platform for designing new systems for the adsorptive separation of ethane and ethylene and thus, reducing the environmental impact of ethylene production.

47

Kim, Seongho, and Xiang Zhang. "Comparative Analysis of Mass Spectral Similarity Measures on Peak Alignment for Comprehensive Two-Dimensional Gas Chromatography Mass Spectrometry." Computational and Mathematical Methods in Medicine 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/509761.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Peak alignment is a critical procedure in mass spectrometry-based biomarker discovery in metabolomics. One of peak alignment approaches to comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC-MS) data is peak matching-based alignment. A key to the peak matching-based alignment is the calculation of mass spectral similarity scores. Various mass spectral similarity measures have been developed mainly for compound identification, but the effect of these spectral similarity measures on the performance of peak matching-based alignment still remains unknown. Therefore, we selected five mass spectral similarity measures, cosine correlation, Pearson’s correlation, Spearman’s correlation, partial correlation, and part correlation, and examined their effects on peak alignment using two sets of experimental GC×GC-MS data. The results show that the spectral similarity measure does not affect the alignment accuracy significantly in analysis of data from less complex samples, while the partial correlation performs much better than other spectral similarity measures when analyzing experimental data acquired from complex biological samples.

48

Alli, Ahmad, Fathima Paruk, Claire Roger, Jeffrey Lipman, Daren Calleemalay, Steven C. Wallis, Juan Scribante, Guy A. Richards, and Jason A. Roberts. "Peri-operative pharmacokinetics of cefazolin prophylaxis during valve replacement surgery." PLOS ONE 18, no. 9 (September 20, 2023): e0291425. http://dx.doi.org/10.1371/journal.pone.0291425.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Objective There is little prospective data to guide effective dosing for antibiotic prophylaxis during surgery requiring cardiopulmonary bypass (CPB). We aim to describe the effects of CPB on the population pharmacokinetics (PK) of total and unbound concentrations of cefazolin and to recommend optimised dosing regimens. Methods Patients undergoing CPB for elective cardiac valve replacement were included using convenience sampling. Intravenous cefazolin (2g) was administered pre-incision and re-dosed at 4 hours. Serial blood and urine samples were collected and analysed using validated chromatography. Population PK modelling and Monte-Carlo simulations were performed using Pmetrics® to determine the fractional target attainment (FTA) of achieving unbound concentrations exceeding pre-defined exposures against organisms known to cause surgical site infections for 100% of surgery (100% fT>MIC). Results From the 16 included patients, 195 total and 64 unbound concentrations of cefazolin were obtained. A three-compartment linear population PK model best described the data. We observed that cefazolin 2g 4-hourly was insufficient to achieve the FTA of 100% fT>MIC for Staphylococcus aureus and Escherichia coli at serum creatinine concentrations ≤ 50 μmol/L and for Staphylococcus epidermidis at any of our simulated doses and serum creatinine concentrations. A dose of cefazolin 3g 4-hourly demonstrated >93% FTA for S. aureus and E. coli. Conclusions We found that cefazolin 2g 4-hourly was not able to maintain concentrations above the MIC for relevant pathogens in patients with low serum creatinine concentrations undergoing cardiac surgery with CPB. The simulations showed that optimised dosing is more likely with an increased dose and/or dosing frequency.

49

Huang, Canyi, Keding Li, Jianqiang Du, Bin Nie, Guoliang Xu, Wangping Xiong, and Jigen Luo. "Research on Hybrid Feature Selection Method Based on Iterative Approximation Markov Blanket." Computational and Mathematical Methods in Medicine 2020 (April 7, 2020): 1–11. http://dx.doi.org/10.1155/2020/8308173.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

The basic experimental data of traditional Chinese medicine are generally obtained by high-performance liquid chromatography and mass spectrometry. The data often show the characteristics of high dimensionality and few samples, and there are many irrelevant features and redundant features in the data, which bring challenges to the in-depth exploration of Chinese medicine material information. A hybrid feature selection method based on iterative approximate Markov blanket (CI_AMB) is proposed in the paper. The method uses the maximum information coefficient to measure the correlation between features and target variables and achieves the purpose of filtering irrelevant features according to the evaluation criteria, firstly. The iterative approximation Markov blanket strategy analyzes the redundancy between features and implements the elimination of redundant features and then selects an effective feature subset finally. Comparative experiments using traditional Chinese medicine material basic experimental data and UCI’s multiple public datasets show that the new method has a better advantage to select a small number of highly explanatory features, compared with Lasso, XGBoost, and the classic approximate Markov blanket method.

50

Yáñez-Serrano, Ana María, Anke Christine Nölscher, Efstratios Bourtsoukidis, Eliane Gomes Alves, Laurens Ganzeveld, Boris Bonn, Stefan Wolff, et al. "Monoterpene chemical speciation in a tropical rainforest:variation with season, height, and time of dayat the Amazon Tall Tower Observatory (ATTO)." Atmospheric Chemistry and Physics 18, no. 5 (March 8, 2018): 3403–18. http://dx.doi.org/10.5194/acp-18-3403-2018.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Abstract. Speciated monoterpene measurements in rainforest air are scarce, but they are essential for understanding the contribution of these compounds to the overall reactivity of volatile organic compound (VOC) emissions towards the main atmospheric oxidants, such as hydroxyl radicals (OH), ozone (O3) and nitrate radicals (NO3). In this study, we present the chemical speciation of gas-phase monoterpenes measured in the tropical rainforest at the Amazon Tall Tower Observatory (ATTO, Amazonas, Brazil). Samples of VOCs were collected by two automated sampling systems positioned on a tower at 12 and 24 m height and analysed using gas chromatography–flame ionization detection. The samples were collected in October 2015, representing the dry season, and compared with previous wet and dry season studies at the site. In addition, vertical profile measurements (at 12 and 24 m) of total monoterpene mixing ratios were made using proton-transfer-reaction mass spectrometry. The results showed a distinctly different chemical speciation between day and night. For instance, α-pinene was more abundant during the day, whereas limonene was more abundant at night. Reactivity calculations showed that higher abundance does not generally imply higher reactivity. Furthermore, inter- and intra-annual results demonstrate similar chemodiversity during the dry seasons analysed. Simulations with a canopy exchange modelling system show simulated monoterpene mixing ratios that compare relatively well with the observed mixing ratios but also indicate the necessity of more experiments to enhance our understanding of in-canopy sinks of these compounds.

Статті в журналах з теми "Chromatography modelling and simulation"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями