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Journal articles on the topic 'Diffusion-controlled system'

Author: Grafiati

Published: 28 May 2022

Last updated: 18 July 2025

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Singh, Rajinder, P. Matharu, and J. K. Lalla. "A Diffusion Controlled Drug Delivery System for Theophylline." Drug Development and Industrial Pharmacy 20, no. 7 (1994): 1225–38. http://dx.doi.org/10.3109/03639049409038363.

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Hannech, El-B., and C. R. Hall. "Diffusion controlled reactions in Au/Pb–Sn solder system." Materials Science and Technology 8, no. 9 (1992): 817–24. http://dx.doi.org/10.1179/mst.1992.8.9.817.

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Desaulniers, Donald E., Ronald S. Kaufmann, John A. Cherry, and Harold W. Bentley. "37Cl-35Cl variations in a diffusion-controlled groundwater system." Geochimica et Cosmochimica Acta 50, no. 8 (1986): 1757–64. http://dx.doi.org/10.1016/0016-7037(86)90137-7.

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Li, Xin, Bin Jiang, Hong Yang, Xiang Sheng Xia, Jia Hong Dai, and Fu Sheng Pan. "Solid–Liquid Diffusion and Phase Growth Kinetics in Mg-Ca Binary System." Materials Science Forum 816 (April 2015): 418–23. http://dx.doi.org/10.4028/www.scientific.net/msf.816.418.

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The solid–liquid diffusion between Mg and Mg-10 at.% Ca alloy was studied at a temperature range of 570°C to 630°C for 10, 20, 30min, respectively. Only one compound, Mg2Ca, was observed in the diffusion couples. As the diffusion time increased, the dendritic structure of the diffusion layer became coarser. The thickness of the diffusion layer had an exponential relation to the experimental temperature. The Mg2Ca phase was observed to follow parabolic growth with diffusion time, which suggested that the growth of the Mg2Ca phase was controlled by diffusion mechanism. The activation energy was determined to be 111.28 kJ/mol.

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Kasahara, Kento, and Hirofumi Sato. "A theory of diffusion controlled reactions in polyatomic molecule system." Journal of Chemical Physics 145, no. 19 (2016): 194502. http://dx.doi.org/10.1063/1.4967400.

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Liu, Yongfeng, Kun Luo, Yifan Zhou, Mingxia Gao, and Hongge Pan. "Diffusion controlled hydrogen desorption reaction for the LiBH4/2LiNH2 system." Journal of Alloys and Compounds 481, no. 1-2 (2009): 473–79. http://dx.doi.org/10.1016/j.jallcom.2009.02.142.

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Dekker, L., and S. W. Brok. "Analysis And Simulation Of A Twodimensional Boundary-Controlled Diffusion System." International Journal of Modelling and Simulation 9, no. 3 (1989): 69–72. http://dx.doi.org/10.1080/02286203.1989.11760072.

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Mauri, Emanuele, Anna Negri, Erica Rebellato, Maurizio Masi, Giuseppe Perale, and Filippo Rossi. "Hydrogel-Nanoparticles Composite System for Controlled Drug Delivery." Gels 4, no. 3 (2018): 74. http://dx.doi.org/10.3390/gels4030074.

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Biodegradable poly(ethylene glycol)-block-poly(-lactic acid) (PEG-b-PLA) nanoparticles (NPs) were prepared by nanoprecipitation with controlled dimension and with different electric charges, as monitored by dynamic light scattering (DLS). Then NPs were loaded within hydrogels (HG) developed for biomedical applications in the central nervous system, with different pore sizes (30 and 90 nm). The characteristics of the resulting composite hydrogel-NPs system were firstly studied in terms of ability to control the release of small steric hindrance drug mimetic. Then, diffusion-controlled release of different charged NPs from different entangled hydrogels was studied in vitro and correlated with NPs electric charges and hydrogel mean mesh size. These studies showed different trends, that depend on NPs superficial charge and HG mesh size. Release experiments and diffusion studies, then rationalized by mathematical modeling, allowed us to build different drug delivery devices that can satisfy different medical needs.

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Boldhane, Sanjay, and Bhanudas Kuchekar. "Development and optimization of metoprolol succinate gastroretentive drug delivery system." Acta Pharmaceutica 60, no. 4 (2010): 415–25. http://dx.doi.org/10.2478/v10007-010-0031-x.

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Development and optimization of metoprolol succinate gastroretentive drug delivery systemMetoprolol succinate (MS) gastroretentive (GR) controlled release system was formulated to increase gastric residence time leading to improved drug bioavailability. Box-Behnken model was followed using novel combinations of sodium alginate (SA), sodium carboxymethylcellulose (NaCMC), magnesium alumino metasilicate (MAS) as independent variables. Floating lag time (Flag),t25,t50,t75, diffusion exponent as dependent variables revealed that the amount of SA, NaCMC and MAS have a significant effect (p< 0.05) ont25,t50,t75and Flag. MSGR tablets were prepared and evaluated for mass, thickness, hardness, friability, drug content and floating property. Tablets were studied for dissolution for 24 h and exhibited controlled release of MS with floating for 16 h. The release profile of the optimized batch MS01 fitted first-order kinetics (R2= 0.9868,n= 0.543), indicating non-Fickian diffusion or anomalous transport by diffusion and swelling.

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Limpongsa, Ekapol, and Kraisri Umprayn. "Preparation and Evaluation of Diltiazem Hydrochloride Diffusion-Controlled Transdermal Delivery System." AAPS PharmSciTech 9, no. 2 (2008): 464–70. http://dx.doi.org/10.1208/s12249-008-9062-8.

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Lerch, M. "Diffusion controlled formation of β type phases in the system ZrO2_Zr3N4". Solid State Ionics 95, № 1-2 (1997): 87–93. http://dx.doi.org/10.1016/s0167-2738(96)00549-8.

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Hanika, Jiří, and Vladimíra Ehlová. "Effect of internal diffusion on kinetics of liquid phase hydrogenation and disproportionation of the cyclohexene on palladium catalysts." Collection of Czechoslovak Chemical Communications 54, no. 11 (1989): 3003–10. http://dx.doi.org/10.1135/cccc19893003.

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Kinetics of the side reactions represented by the system involving hydrogenation and disproportionation of cyclohexene on a commercial catalyst CHEROX 41-00 (3%Pd/C) and on a supported palladium catalyst prepared by impregnation of aluminia with aqueous palladium dichloride (2.15% Pd/γ-Al2O3) have been investigated. As follows from the effectiveness factors of internal diffusion for individual reactions, in the region of internal diffusion, cyclohexene hydrogenation is preferred compared to disproportionation. This finding can be related to the fact that while the rate of disproportionation is controlled by cyclohexene diffusion, the rate of hydrogenation is controlled by diffusion of hydrogen.

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Boeck, T., and P. Rudolph. "The influence of thermal diffusion on the travelling heater method in a diffusion controlled growth system." Journal of Crystal Growth 79, no. 1-3 (1986): 105–9. http://dx.doi.org/10.1016/0022-0248(86)90423-9.

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Krupp, Ulrich, Katrin Jahns, Kamil Balinski, and Jürgen Wübbelmann. "Numerical Analysis of Diffusion-Controlled Internal Corrosion by the Cellular Automata Approach." Defect and Diffusion Forum 383 (February 2018): 51–58. http://dx.doi.org/10.4028/www.scientific.net/ddf.383.51.

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The cellular automata method offers a promising approach to describe diffusion and diffusion-controlled precipitation processes at high temperatures. During high temperature exposure, technical components like gas-turbine blades, furnaces, or exhaust systems, are operating in corrosive atmospheres. The resulting material-degradation processes are diffusion‐controlled, and corrosive species penetrate into the material leading to the formation of embrittling precipitates. Cellular automata (CA) represent distributed dynamical systems whose structure is particularly well suited to determine the temporal evolution of the system. In this study, it is shown that the model is able to consider diffusion, nucleation and growth aspects, interdiffusion between scales, and high diffusivity paths like grain boundaries. This has been demonstrated by applying CA to (i) nitrogen diffusion, (ii) internal intergranular oxidation of nickel-based alloy, and (iii) interdiffusion of a binary diffusion couple.

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Kadhim, Murad M., and Qusay A. Abbas. "Bohm Diffusion in Magnetron Sputtering System: A Review Article." Iraqi Journal of Industrial Research 11, no. 3 (2024): 55–68. https://doi.org/10.53523/ijoirvol11i3id462.

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This review provides a comprehensive analysis of recent advances in understanding Bohm diffusion in magnetron sputtering systems, a process critical for optimizing thin-film deposition. Bohm diffusion significantly influences the spatial distribution and energy of sputtered particles near the substrate, impacting the overall film quality and performance. The review delves into theoretical models, experimental findings, and computational simulations to uncover the mechanisms driving Bohm diffusion within the plasma sheath. Key factors, such as magnetic field strength, gas pressure, target-to-substrate distance, and plasma parameters, are examined for their impact on diffusion behaviors and, consequently, film deposition outcomes. By highlighting these interdependencies, the review underscores the importance of Bohm diffusion in achieving controlled, uniform deposition essential for high-performance coatings. Additionally, it addresses how advances in understanding Bohm diffusion can enable more effective tuning of deposition processes to meet specific application requirements in fields ranging from electronics to materials engineering. Through a synthesis of current research, this review offers valuable insights to scientists and engineers aiming to enhance the efficiency and precision of magnetron sputtering for tailored thin-film applications, ultimately contributing to the broader field of thin-film fabrication.

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Anjali, Bhansali Dr. A. Chandewar Dr. Madhuri Channawar Ashwini warnkar Anisha kohale. "Design And Chacterization of Novel Topical Drug Delivery System." International Journal of Pharmaceutical Sciences 3, no. 5 (2025): 2915–25. https://doi.org/10.5281/zenodo.15450341.

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The present study focuses on the design and characterization of a novel topical drug delivery system incorporating Vitex negundo extract through microsponge technology followed by gel formulation. Vitex negundo, known for its potent anti-inflammatory and antimicrobial properties, and microsponges via the quasi-emulsion solvent diffusion technique, employing ethyl cellulose as the polymer and polyvinyl alcohol as the stabilizer. The prepared microsponges were characterized for particle size, surface morphology, entrapment efficiency, and thermal stability using techniques such as, scanning electron microscopy (SEM), and The optimized microsponges were then incorporated into a carbopol-based gel to develop a stable, non-irritant topical formulation. The gel was evaluated for physicochemical parameters, in-vitro drug release, and release kinetics. Results indicated controlled release of the active constituents, enhanced stability, and improved spreadability. This microsponge-based gel system offers a promising approach for the effective topical delivery of herbal actives, providing a controlled and targeted therapeutic effect with minimal side effects.

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Huang, Song, Chengwu Yang, Ge Han, Shengfeng Zhao, and Xingen Lu. "Multipoint design optimization for a controlled diffusion airfoil compressor cascade." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 11 (2020): 2143–59. http://dx.doi.org/10.1177/0954406220904730.

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Under high altitude and low Reynolds number conditions, the aerodynamic performance of compressor cascades deteriorates drastically. In this paper, an optimally designed system combining class-shape-transformation method, S1 surface flow solver and whale optimization algorithm was established to achieve for a controlled diffusion airfoil, called MANGHH. The aim of this work is to improve our understanding of the loss mechanism for the original cascade and optimal cascade under different inflow conditions. The study shows that the total pressure loss of the optimal cascade at an angle of attack of −4°, 0°, and 6° decreases by 55.9%, 16.1%, and 16.3%, respectively, compared with the original controlled diffusion airfoil. The range of the available low loss incidence improves significantly. At different incidences, the optimal cascade moves the blade loading forward compared with that of the original controlled diffusion airfoil while reducing the growth rate of the boundary layer thickness, eliminating a wide range of flow separations. The optimal cascade reduces the total pressure loss mainly by reducing trailing edge mixing loss compared with that of the original controlled diffusion airfoil. Under different inlet Mach number conditions, a laminar separation bubble appears on the suction surface of the original controlled diffusion airfoil. As the inlet Mach number increases, the position of the laminar separation bubble moves slightly upstream, while the length and depth of the laminar separation bubble increase. Fortunately, the total pressure loss of the optimal cascade decreases significantly compared with that of the original controlled diffusion airfoil. Under different incoming turbulence intensity conditions, the total pressure loss of the optimal cascade is always lower than that of the original controlled diffusion airfoil. As the incoming turbulence intensity increases, the total pressure loss of the original controlled diffusion airfoil decreases first and then increases. However, the total pressure loss of the optimal cascade increases with increasing incoming turbulence intensity due to the improvement of the turbulence dissipation capacity.

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Krichagina, Elena V., Sheldon X. C. Lou, Suresh P. Sethi, and Michael I. Taksar. "Diffusion Approximation for a Controlled Stochastic Manufacturing System with Average Cost Minimization." Mathematics of Operations Research 20, no. 4 (1995): 895–922. http://dx.doi.org/10.1287/moor.20.4.895.

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Felderhof, B. U., and R. B. Jones. "Reversible diffusion-controlled reactions in a disordered system of static spherical catalysts." Journal of Chemical Physics 111, no. 9 (1999): 4205–17. http://dx.doi.org/10.1063/1.479719.

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Dekker, L., and S. W. Brok. "Modelling and Stability Analysis of a Boundary Controlled 2-D Diffusion System." IFAC Proceedings Volumes 22, no. 4 (1989): 501–5. http://dx.doi.org/10.1016/s1474-6670(17)53595-8.

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Huang, Y. J., and L. James Lee. "Optimization of diffusion-controlled free radical polymerizations in a distributed parameter system." Chemical Engineering Science 44, no. 2 (1989): 363–76. http://dx.doi.org/10.1016/0009-2509(89)85073-0.

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Pastore, Raffaele, Antonio Ciarlo, Giuseppe Pesce, Antonio Sasso, and Francesco Greco. "A model-system of Fickian yet non-Gaussian diffusion: light patterns in place of complex matter." Soft Matter 18, no. 2 (2022): 351–64. http://dx.doi.org/10.1039/d1sm01133b.

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Mannam, Revathi, and Indira Muzib Yallamalli. "PHARMACOKINETIC STUDY OF MATRIX MEMBRANE MODERATED TRANSDERMAL SYSTEM OF BOSENTAN MONOHYDRATE." Asian Journal of Pharmaceutical and Clinical Research 10, no. 9 (2017): 255. http://dx.doi.org/10.22159/ajpcr.2017.v10i9.19282.

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Objective: The objective of the present research work is to carry out the pharmacokinetic studies of optimized matrix membrane moderatedtransdermal patch of bosentan monohydrate.Materials and Methods: The matrix membrane moderated transdermal system was formulated using HPMC, HPMC K4M and E RLPO. In vitrodiffusion studies were carried out using modified Franz diffusion cell and for the optimized transdermal patch, pharmacokinetic studies were carriedout using New Zealand male rabbits. Plasma samples were quantified using high-performance liquid chromatography.Results: The in vitro diffusion studies revealed that formulation F3 with HPMC K4M and E RLPO had controlled release up to 28 hrs, and a maximumof 95.02±2.68% drug was released. The release kinetics followed mixed order non-Fickian diffusion. The pharmacokinetic studies of the optimizedpatch revealed controlled release up to 45 hrs where a 2.2-fold increase in area under curve (AUC) and 3.8 times increase in mean residence time(MRT) were observed compared to oral route. The results were appeared to be significant at p≤0.05. The variation in half-life was found to be notstatistically significant when compared between oral and transdermal routes.Conclusion: The pharmacokinetic results concluded that the matrix membrane moderated transdermal system with extended AUC and MRT canenhance the bioavailability of bosentan monohydrate by minimizing the drug-related side effects in oral route.

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GHASEMI, MARYAM, STEFANIE SONNER, and HERMANN J. EBERL. "Time adaptive numerical solution of a highly non-linear degenerate cross-diffusion system arising in multi-species biofilm modelling." European Journal of Applied Mathematics 29, no. 6 (2018): 1035–61. http://dx.doi.org/10.1017/s0956792518000554.

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We propose a numerical method for the simulation of a quasi-linear parabolic biofilm model that exhibits three non-linear diffusion effects: (i) a power law degeneracy, (ii) a super diffusion singularity and (iii) non-linear cross-diffusion. The method is based on a spatial Finite Volume discretisation in which cross-diffusion terms are formally treated as convection terms. Time-integration of the resulting semi-discretised system is carried out using an error-controlled, time-adaptive, embedded Rosenbrock–Wanner method. We compare several variants of the method and two variants of the model to investigate how details such as the choice cross-diffusion coefficients, and specific variants of the time integrator affect simulation time.

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Arora, Neha, and Balaji R. Jagirdar. "From (Au5Sn + AuSn) physical mixture to phase pure AuSn and Au5Sn intermetallic nanocrystals with tailored morphology: digestive ripening assisted approach." Phys. Chem. Chem. Phys. 16, no. 23 (2014): 11381–89. http://dx.doi.org/10.1039/c4cp00249k.

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Du, Runmei. "Approximate Controllability of the Degenerate System with the First-Order Term." Journal of Function Spaces 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/151484.

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We consider the approximate controllability of the degenerate system with the first-order term. The first-order term in the equation cannot be controlled by the diffusion term. The system is shown to be approximately controllable by constructing a control by means of its conjugate problem.

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Laporte, V., Krzysztof Wolski, Pascal Berger, A. Terlain, and Gerard Santarini. "Diffusion-Controlled Liquid Bismuth Induced Intergranular Embrittlement of Copper." Defect and Diffusion Forum 237-240 (April 2005): 683–88. http://dx.doi.org/10.4028/www.scientific.net/ddf.237-240.683.

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The consequences of the contact between liquid bismuth and a copper bicrystal are investigated at 500°C. Atoms of bismuth are shown to penetrate and embritlle the copper grain boundary. Grain boundary concentration profiles of bismuth are obtained on fracture surfaces by both Auger electron spectroscopy and He4+ Rutherford backscattering spectroscopy. The maximum bismuth intergranular concentration is calculated from experimental data to be about 1.7 monolayers (near the liquid bismuth / solid copper interface). The overall profiles are significantly different from typical erfc profiles and an interpretation is proposed, based on the coupling effect between grain boundary diffusion and non-linear segregation. These results allow us to conclude on the absence of grain boundary wetting for the Cu / Bi system at 500°C.

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He, Ping, and Yangmin Li. "Analytical solution of a hyperbolic partial differential equation and its application." International Journal of Intelligent Computing and Cybernetics 10, no. 2 (2017): 183–99. http://dx.doi.org/10.1108/ijicc-10-2016-0040.

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Purpose The purpose of this paper is to investigate the analytical solution of a hyperbolic partial differential equation (PDE) and its application. Design/methodology/approach The change of variables and the method of successive approximations are introduced. The Volterra transformation and boundary control scheme are adopted in the analysis of the reaction-diffusion system. Findings A detailed and complete calculation process of the analytical solution of hyperbolic PDE (1)-(3) is given. Based on the Volterra transformation, a reaction-diffusion system is controlled by boundary control. Originality/value The introduced approach is interesting for the solution of hyperbolic PDE and boundary control of the reaction-diffusion system.

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Hasan, Md Nazmul, and Khan Rubayet Rahaman. "Pattern Formation in Intra-Specific Competition Food Chain System with Bifurcation and Chaos Control." International Journal of Bifurcation and Chaos 31, no. 03 (2021): 2150048. http://dx.doi.org/10.1142/s0218127421500486.

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The study is an attempt to explore the competitive effects on the top predators in the tri-trophic food chain model. Holling types II and IV functional responses are used to investigate the complex behavior of the tri-trophic prey–predator system. Reaction–diffusion systems have been used to represent temporal evolution and spatial interaction among the species. Consequently, local and global stabilities, and Hopf-bifurcation have been analyzed. The numerical simulation leads to spontaneous and interesting pattern formation in two dimensions, signifying diffusion interaction between mid- and top-level predators. The effect of diffusion on the chaotic dynamics of the model systems is also investigated. It is found that the chaos mechanism wave-like behavior of the chaotic attractor exists for a long time. The diffusion of this long-term behavior is controlled by using Hybrid Control Strategy.

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Furuto, Akira, and Masanori Kajihara. "Numerical Analysis for Kinetics of Reactive Diffusion Controlled by Boundary and Volume Diffusion in a Hypothetical Binary System." MATERIALS TRANSACTIONS 49, no. 2 (2008): 294–303. http://dx.doi.org/10.2320/matertrans.mra2007192.

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AITTA, ANNELI, HERBERT E. HUPPERT, and M. GRAE WORSTER. "Diffusion-controlled solidification of a ternary melt from a cooled boundary." Journal of Fluid Mechanics 432 (April 10, 2001): 201–17. http://dx.doi.org/10.1017/s0022112000003232.

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We present details of an experimental study of crystallization adjacent to a cooled boundary from an aqueous solution of potassium nitrate and sodium nitrate. This transparent system is typical of many ternary melts that do not form solid solutions, including examples in igneous petrology and metallurgy. We have measured the rates of advance of the front of crystallization and the eutectic front, behind which the system is completely solid. From careful measurements of the concentration and temperature fields, we have been able to infer the location of an internal phase boundary: the cotectic front separating a region in which only one component of the ternary system forms crystals from a region in which two components form crystals. Our experiments were conducted under conditions in which fluid flow is minimal, so that rates of crystallization are determined principally by the diffusive transport of heat. We have confirmed that the thicknesses of the various regions all grow in proportion to the square root of time, as is expected of diffusion-limited growth, and have determined the constants of proportionality for a range of different initial concentrations and boundary temperatures. We have found evidence to suggest that there may be a significant nucleation delay in the secondary and tertiary crystallization. Our measurements of concentration provide much more information about the ternary phase diagram than has hitherto been available.

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Zaman, Muhammad, Junaid Qureshi, Hira Ejaz, et al. "Oral controlled release drug delivery system and Characterization of oral tablets; A review." Pakistan Journal of Pharmaceutical Research 2, no. 1 (2016): 67. http://dx.doi.org/10.22200/pjpr.2016167-76.

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Oral route of drug administration is considered as the safest and easiest route of drug administration. Control release drug delivery system is the emerging trend in the pharmaceuticals and the oral route is most suitable for such kind of drug delivery system. Oral route is more convenient for It all age group including both pediatric and geriatrics. There are various systems which are adopted to deliver drug in a controlled manner to different target sites through oral route. It includes diffusion controlled drug delivery systems; dissolution controlled drug delivery systems, osmotically controlled drug delivery systems, ion-exchange controlled drug delivery systems, hydrodynamically balanced systems, multi-Particulate drug delivery systems and microencapsulated drug delivery system. The systems are formulated using different natural, semi-synthetic and synthetic polymers. The purpose of the review is to provide information about the orally controlled drug delivery system, polymers which are used to formulate these systems and characterizations of one of the most convenient dosage form which is the tablets.

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Gliko, Olga, Nicholas A. Booth, and Peter G. Vekilov. "Step bunching in a diffusion-controlled system: phase-shifting interferometry investigation of ferritin." Acta Crystallographica Section D Biological Crystallography 58, no. 10 (2002): 1622–27. http://dx.doi.org/10.1107/s0907444902014324.

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Baheti, Varun A., Sanjay Kashyap, Praveen Kumar, Kamanio Chattopadhyay, and Aloke Paul. "Solid–state diffusion–controlled growth of the phases in the Au–Sn system." Philosophical Magazine 98, no. 1 (2017): 20–36. http://dx.doi.org/10.1080/14786435.2017.1392052.

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Chamarthy, Sai Prasanth, and Rodolfo Pinal. "Plasticizer concentration and the performance of a diffusion-controlled polymeric drug delivery system." Colloids and Surfaces A: Physicochemical and Engineering Aspects 331, no. 1-2 (2008): 25–30. http://dx.doi.org/10.1016/j.colsurfa.2008.05.047.

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Kandasamy, Palani, and Souti Mukherjee. "Enhancing shelf life of tomato under controlled atmosphere condition using diffusion channel system." Engineering in Agriculture, Environment and Food 12, no. 1 (2019): 1–10. http://dx.doi.org/10.1016/j.eaef.2018.07.001.

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Irfan, Sayed Ameenuddin, and Radzuan Razali. "Mathematical modelling of controlled release fertilizer." Malaysian Journal of Fundamental and Applied Sciences 13, no. 4-1 (2017): 372–74. http://dx.doi.org/10.11113/mjfas.v13n4-1.878.

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Controlled release fertilizers (CRFs) are essential for sustainable agriculture system. CRFs are designed to maintain the constant optimum release rate of nutrients from the coated granule. This increase the plant uptake of nutrients hence reduces the soil pollution and decreases the crop expenditure. In the literature, the maximum studies have been done by considering the molecular diffusion as the only phenomenon responsible for nutrient release from CRFs. The molecular diffusion model is solved mostly by using the variable separable methods and Laplace transform as well as finite difference methods by different researchers. The release of NPK (nutrient) depends on both molecular diffusions which are expressed by Fick’s second law of diffusion and ionic diffusion, due to the electrolytic behavior of NPK in the soil. In this work, an analytical solution is presented. The obtained solution helps to find the effect of granule coating thickness, nutrient release rate, pH of the soil and temperature of the soil on the nutrient release profiles.

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Fairchild, Robert W., Stephen Long, and Andrew Yule. "IMPLEMENTING A NEW DIFFUSION BATTERY FOR RADON PROGENY DOSE DETERMINATION." Radiation Protection Dosimetry 188, no. 3 (2020): 311–15. http://dx.doi.org/10.1093/rpd/ncz288.

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Abstract The Australian Radiation Laboratory Diffusion Battery was created in 1992 to evaluate radon progeny dose coefficients based on measured aerosol conditions. The Australian Radiation Laboratory Diffusion Battery used filters, alpha counters and a legacy laptop computer running a PowerBASIC program that controlled the hardware. Because technology has evolved, the original system is not supportable. A replacement system consisting of separate hardware and software modules has been created. The hardware counting module is based on the proven design of the Effective Dosimeter, using modern detectors, electronics, flow sensors, a microcontroller and a secure digital memory card for data storage. The analysis of the data has been implemented in an Excel spreadsheet with Visual Basic for Applications coding to do loops and iterations. Tests of the software with current and historic data sets, all taken with the original Australian Radiation Laboratory Diffusion Battery system, have validated a modern, supportable diffusion battery system.

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Mondal, Nita. "THE ROLE OF MATRIX TABLET IN DRUG DELIVERY SYSTEM." International Journal of Applied Pharmaceutics 10, no. 1 (2018): 1. http://dx.doi.org/10.22159//ijap.2018v10i1.21935.

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Matrix tablet is an important tool for controlled and sustained release dosage forms. The oral route remains the most common route for the administration of drugs. Tablets offer the lowest cost approach to sustained and controlled release dosage forms. The hydrophilic polymer matrix is widely used in this dosage form. The use of different polymers in controlling the release of drugs has become the most important tool in the formulation of matrix tablets. The drug releases by both dissolution-controlled as well as diffusion-controlled mechanisms from the matrix. The development of oral controlled release systems has been a challenge to formulation scientists due to their inability to restrain and localize the system at targeted areas of the gastrointestinal tract. There are several advantages of matrix devices including improved patient compliance due to less frequent drug administration, reduction of fluctuation in steady-state drug levels, maximum utilization of the drug, increased safety margin of a potent drug. This review aims on the discussion of different materials used to prepare matrix tablets, different types of matrix tablets and the drug release mechanism from the matrices.

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Tani, Jun-ichi, Guerman Popov, Paul R. Mort, and Richard E. Riman. "Precursor and processing effects on BaPbO3 formation kinetics." Journal of Materials Research 21, no. 3 (2006): 584–96. http://dx.doi.org/10.1557/jmr.2006.0071.

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The synthesis of BaPbO3 from a wide range of mixtures containing metalorganic precursors, nitrate precursors, lead oxides, barium oxide and peroxide was investigated, and the kinetics was analyzed using the Johnson–Mehl–Avrami (JMA) equation. It was found that Ba and Pb stearate soaps and Pb oxalate that were used as metalorganic precursors formed BaCO3 and PbO or Pb3O4 after firing at 440 °C. The formation rate of BaPbO3 from a metalorganic precursor system is not higher than that from the conventional BaCO3–PbO system and does not depend on mixing methods or the kinds of metalorganic precursors but instead on the synthesis atmosphere. In the case of the BaCO3–PbO system, the Avrami exponent (n) is ∼1, indicating that the reaction is controlled by the phase-boundary-contraction interface reaction. For the BaO2–PbO2 system, n has two values ∼1 and ∼0.3, depending on the reaction temperature and time, indicating that the reaction is either controlled by the phase-boundary-contraction interface reaction or diffusion-controlled reaction. In the Ba nitrate–Pb nitrate system, phase-pure BaPbO3 is obtained at 550 °C, which is 250 °C lower than in the case of the BaCO3–PbO system. The value of n for the nitrate system is ∼1.5, indicating that the reaction is controlled by a three-dimensional (3D) diffusion-controlled nucleation mechanism. In the BaO–PbO system, the formation of BaPbO3 started at 350 °C by an exothermic reaction and the content of BaPbO3 in the product was ∼40 wt%, which is independent of reaction temperature as well as time in the temperature range of 350–500 °C.

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Schablitzki, T., J. Rogal, and R. Drautz. "A kinetic Monte Carlo approach to diffusion-controlled thermal desorption spectroscopy." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375, no. 2098 (2017): 20160404. http://dx.doi.org/10.1098/rsta.2016.0404.

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Atomistic simulations of thermal desorption spectra for effusion from bulk materials to characterize binding or trapping sites are a challenging task as large system sizes as well as extended time scales are required. Here, we introduce an approach where we combine kinetic Monte Carlo with an analytic approximation of the superbasins within the framework of absorbing Markov chains. We apply our approach to the effusion of hydrogen from BCC iron, where the diffusion within bulk grains is coarse grained using absorbing Markov chains, which provide an exact solution of the dynamics within a superbasin. Our analytic approximation to the superbasin is transferable with respect to grain size and elliptical shapes and can be applied in simulations with constant temperature as well as constant heating rate. The resulting thermal desorption spectra are in close agreement with direct kinetic Monte Carlo simulations, but the calculations are computationally much more efficient. Our approach is thus applicable to much larger system sizes and provides a first step towards an atomistic understanding of the influence of structural features on the position and shape of peaks in thermal desorption spectra. This article is part of the themed issue ‘The challenges of hydrogen and metals’.

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Klümper-Westkamp, Heinrich, Marian G. Skalecki, and Hans-Werner Zoch. "Sensor system for controlled carbonitriding." Matériaux & Techniques 106, no. 1 (2018): 102. http://dx.doi.org/10.1051/mattech/2018027.

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Carbonitriding is mainly used to enhance the hardenability and wear resistance of unalloyed steels. Last year investigations have shown that improved component properties can efficiently be obtained by carbonitriding also low alloy and even higher alloy steels. The importance of carbonitriding rises. In the past, carbonitriding was done with constant ammonia additions, e.g. 2–5 vol% are added to the carburizing atmosphere without controlling or measuring the nitriding potential of the atmosphere. The results scatter in a wide rage depending on furnace, batch size and load and many other influencing factors. The need for a control system is obvious. The presented sensor system allows carbonitriding processes, where carbon and nitrogen potentials of the atmosphere are controlled. This allows adjusting surface carbon and nitrogen contents to desired values independently and guarantees constant product quality. The sensor system consists of a combination of an ammonia and an oxygen sensor and simulation software. By this way online diffusion profile calculation for carbon and nitrogen are possible even for alloyed steels taking alloy factors for both into account. These alloy factors, measured for many steel grades and phase boundaries, were calculated with Thermocalc.

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Guo Si-Hang, Yang Guang-Yu, Meng Guo-Qing, Wang Ying-Ying, Pan Jun-Xing, and Zhang JinJun. "Dynamic Self-Assembly of Active Particle Systems Controlled by Light Fields." Acta Physica Sinica 74, no. 9 (2025): 0. https://doi.org/10.7498/aps.74.20241556.

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Active particle systems are nonequilibrium systems composed of selfpropelled Brownian particles, where interactions between particles can give rise to various collective behaviors. This study, based on Brownian dynamics simulations, explores the effects of light intensity, rotational diffusion coefficient, and the width and spacing of illuminated regions on the aggregation structures of the system. First, this study examines the influence of light intensity on aggregation structures under different rotational diffusion coefficients, finding that as the rotational diffusion coefficient increases, the system gradually stabilizes. This stabilization is attributed to the reduced collision effects among particles at higher diffusion coefficients. Under suitable rotational diffusion coefficients, gradually increasing the ratio of longitudinal to transverse light-induced self-propulsion forces leads to a transition in the system's aggregation structure from a transverse stripe structure configuration to a tic-tac-toe structure, ultimately resulting in a longitudinal stripe structure. This indicates that the system's aggregation structure can be effectively controlled by varying the relative light intensities of the longitudinal and transverse illumination. From a dynamical perspective, unstable structures consistently exhibit a super-diffusive behavior throughout the simulations, while stable structures transition from initial super-diffusion to normal diffusion, indicating that under steady state conditions, particles aggregate in the shaded regions, exhibiting Brownian motion. To further investigate the influence of light fields on collective particle behavior, this study systematically varied the width of the illuminated regions and the spacing between adjacent illuminated regions, finding that the overall trends were consistent with previous conclusions. It was also observed that wider illuminated regions with narrower spacing facilitate the formation of tictac-toe structures, while narrower illuminated regions with wider spacing tend to lead to the emergence of a novel structure—checkerboard structures. This study investigates the phase separation behavior of particles in complex optical field environments, providing valuable insights for controlling aggregation states in active particle systems.

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Backhaus-Ricoult, M., and R. Dieckmann. "Defects and Cation Diffusion in Magnetite (VII): Diffusion Controlled Formation of Magnetite During Reactions in the Iron-Oxygen System." Berichte der Bunsengesellschaft für physikalische Chemie 90, no. 8 (1986): 690–98. http://dx.doi.org/10.1002/bbpc.19860900814.

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Zhang, Xinming, Yi Li, and Youhua Fan. "Regularization Cuckoo Search Algorithm for Multi-Parameter Optimization of the Multi-Laminated Controlled Release System." Axioms 11, no. 10 (2022): 500. http://dx.doi.org/10.3390/axioms11100500.

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The multi-laminated controlled release system has been widely used in the modern pharmaceutical industry because of its simple structure and safety, which can control the drug release behavior by regulating its internal parameters. To achieve three desired drug release behaviors of constant rate, linear reduction, and nonlinearity, which can be controlled by the optimization of the controllable parameters in the controlled release system, such as initial concentration and diffusion coefficient, a new regularization cuckoo search algorithm based on the cuckoo search algorithm and Tikhonov regularization method is proposed. The numerical examples confirm the stability, effectiveness, and feasibility of the proposed method. The effect of the number of model layers on the optimization results is also analyzed.

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Kalishyn, Yevhen Yu, Małgorzata Rachwalska, and Peter E. Strizhak. "Stirring Effect on the Belousov-Zhabotinsky Oscillating Chemical Reactions in a Batch. Experimental and Modelling." Zeitschrift für Naturforschung A 65, no. 1-2 (2010): 132–40. http://dx.doi.org/10.1515/zna-2010-1-215.

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AbstractWe have studied the stirring effect on the time-delayed bifurcations of transient oscillations in the Belousov-Zhabotinsky (BZ) oscillating chemical reaction in a closed system. Experiments show that oscillations disappear through the time-delayed Hopf bifurcations, whose parameters depend on the stirring rate. The explanation of the stirring effect is based on the theories of diffusion-controlled reactions and hydrodynamic turbulence. We show that an increase of the stirring rate leads to an increase of the rate constant for the diffusion-controlled reaction. We propose a kinetic scheme that describes the effect observed in the experiments. A good agreement between the experimental data and the simulations is obtained.

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Lee, Sean. "Investigating the Feasibility of Xylitol and Gelatin for Controlled Release System in Drug Delivery using Calcium Alginate." Journal of International Research in Medical and Pharmaceutical Sciences 19, no. 3 (2024): 52–69. http://dx.doi.org/10.56557/jirmeps/2024/v19i38890.

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Calcium Alginate-based beads have been recognized to have high potential for pharmaceutical applications thanks to their ease of use and biocompatibility. This study aims to investigate how xylitol and gelatin could be used for a controlled drug delivery system and how to manipulate such a delivery system. For the study, calcium alginate beads were synthesized using two different calcium compounds: calcium lactate (CL) and calcium chloride (CC). Varying concentrations of the calcium compounds in the beads were prepared to measure their effects on their characteristics, such as size, weight, strength, and, most importantly, the diffusion rate. The study attempted to manipulate the diffusion rates by incorporating xylitol and gelatin into the calcium alginate membrane. A comparative analysis revealed that CC and CL affected the beads differently. For instance, bead size increased with CC concentration up to 5%, after which it decreased, while CL showed a more consistent decrease in size as concentration increased. Weight generally decreased with higher concentrations of both CC and CL, but the reduction was more pronounced with CL. The popping force increased with CC concentration but had a non-linear relationship with CL, reaching around 7% concentration before decreasing. The study also examined the percentage change in weight after 48 hours of drying. For smaller beads (3mm), the weight change decreased with higher CC concentration, but for larger beads (7.05mm), the trend reversed, showing an increase in weight change at higher concentrations. Similar patterns were observed for CL, with weight change initially decreasing but increasing with higher concentrations. Our diffusion studies found that the xylitol concentration generally enhanced diffusion rates, with CL beads showing a greater initial diffusion than CC beads. In contrast, gelatin concentration has less predictable effects on diffusion rates. For CL beads, more gelatin results in less dye diffusion, suggesting that gelatin may impact the initial release of dye from the beads.

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Korosteleva, E. N., A. G. Knyazeva, M. A. Anisimova, and I. O. Nikolaev. "The impact of impurities on the Al–Fe–C system phase composition changes during sintering." Powder Metallurgy аnd Functional Coatings 17, no. 2 (2023): 5–13. http://dx.doi.org/10.17073/1997-308x-2023-2-5-13.

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Manufacturing waste can be not only recycled but also utilized as a source of chemical elements and as a component of powder materials. Steel swarf are a complex multicomponent material with a high iron content, while impurities such as carbon can affect the diffusion interaction in the chip and metal powder mixture. In this study, we investigate the diffusion interaction between aluminum and steel swarf using temperature-controlled vacuum sintering. We analyzed the resulting mixture’s microstructure and phase composition, and observed that sintering creates a multiphase structure in which FeAl iron aluminide occupies at least 30 vol. %. Despite the high sintering temperature, we also observed residual aluminum and iron. Incomplete transformation may result form refractory products that inhibit diffusion or impurities that influence the magnitude and direction of the diffusion fluxes. To confirm the impurities’ role in the diffusion interaction kinetics, we developed simulation models of the intermetallic phase growth for a flat and spherical particle embedded in aluminum. The model consider cross-diffusion fluxes in the emerging phase regions and possible effects of impurities on the concentration limit for the new phase’s existence. We derived approximate analytical solutions to analyze the emerging phase growth trends under various model parameters.

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Chen, Y. C., Hong Zhi Cui, J. Ding, and Yun Bo Chen. "Experiments Proving the Mixed Control of the Reactive Diffusion System Zn/Fe₃Si with Clamp Press." Defect and Diffusion Forum 258-260 (October 2006): 59–62. http://dx.doi.org/10.4028/www.scientific.net/ddf.258-260.59.

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More than twenty years were needed for people to understand the formation mechanism of the periodic-layered structures not only because of the complications of pattern formation, but also due to the limits of traditional diffusion theories. Based on the general theory of interdiffusion growth proposed by Y.C. Chen et al. [1], the quantitative model of periodic layer formation during solid state reactions has been succeeded [2]. The experimental results shown in this paper proved one of the model’s predicts that the reactive diffusion system Zn/Fe3Si with clamp press annealed at 663K should be mixed controlled. Also, the important influence of the uniaxial compressive stress on the diffusion coefficient was emphasized and the reasons are discussed.

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Wróbel, Marek, and Andriy Burbelko. "A Diffusion Model of Binary Systems Controlled by Chemical Potential Gradient." Journal of Casting & Materials Engineering 6, no. 2 (2022): 39–44. http://dx.doi.org/10.7494/jcme.2022.6.2.39.

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The paper presents a model of diffusion in a single phase with chemical potential gradient as the driving force of the process. Fick’s laws are strictly empirical and the assumption that the concentration gradients are the driving forces of diffusion is far from precise. Instead, the gradient of chemical potential μi of component i is the real driving force. The matter of governing equations of models that incorporate this approach will be raised and discussed in this article. One of more important features is the ability to acquire results where diffusion against the concentration gradient may occur. The presented model uses the Finite Difference Method (FDM) and employs the CALPHAD method to obtain chemical potentials. The calculations of chemical potential are carried out for instant conditions – temperature and composition – in the entire task domain by Thermo-Calc via a TQ-Interface. Then the heterogeneity of chemical potentials is translated into mass transfer for each individual element. Calculations of two modelling tasks for one-dimension diffusion field were carried out. First: isothermal conditions with linear initial composition distribution and second: constant temperature gradient with uniform chemical composition in the specimen. Results for two binary solid solutions: Fe-C and Fe-Si, in the FCC phase for the given tasks will be presented. Modelling allows us to estimate the time needed to reach a desired state in a particular equilibrium or quasi-equilibrium state. It also shows the path of the composition change during the process. This can be used to determine whether the system at some point is getting close to the formation of another phase due to significant deviation from its initial conditions.

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