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Panjaitan, Jabosar Ronggur Hamonangan, David Andrian Padang, Aziz Fatchurohman, and Fourka Fitra Ramadhan. "Hydrolysis Kinetics of Bacterial Cellulose Using Sodium Hydroxide." Reka Buana : Jurnal Ilmiah Teknik Sipil dan Teknik Kimia 8, no. 1 (March 30, 2023): 79–87. http://dx.doi.org/10.33366/rekabuana.v8i1.4433.
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The hydrolysis reaction is a rupture reaction of reactants with water which is generally used to produce useful derivative products and can be reviewed for kinetics as a basis for reactor design. Nata or bacterial cellulose is a compound consisting of pure cellulose and water so that it can be hydrolyzed to produce various cellulose degradation products. This research examined the kinetic hydrolysis of bacterial cellulose using a sodium hydroxide catalyst. This study aimed to determine the kinetic parameters of the nata hydrolysis reaction using a base sodium hydroxide catalyst. The results showed higher temperatures and longer hydrolysis time performed better in hydrolysis reactions. The hydrolysis kinetics in this study were divided into two types, Type 1 hydrolysis kinetics which used the wet weight of bacterial cellulose, and Type 2, which used the dry weight of bacterial cellulose. From the calculation results, the order of bacterial cellulose hydrolysis reaction ranges from 5 – 6, with the kinetic constants of Type 1 hydrolysis kinetics at 40oC, 60oC, and 80oC were 0.000012, 40,255.4, and 299,839 min-1. In comparison, the reaction constants of Type 2 hydrolysis kinetics at 40oC, 60oC, and 80oC were 0.516851, 1.124119, and 2.408972 min-1. The activation energy of Type 1 hydrolysis kinetics was 558.3932 kJ/mol, and Type 2 hydrolysis kinetics was 35.31205 kJ/mol. The difference in kinetic parameter values for Types 1 and 2 will be a reference in designing a nata hydrolysis reactor from wet and dry nata reactants to produce various cellulose degradation compounds.ABSTRAKReaksi hidrolisis merupakan reaksi pemecahan reaktan dengan air yang umumnya dilakukan untuk memproduksi produk – produk turunan bermanfaat dan dapat ditinjau kinetikanya sebagai dasar dalam perancangan reaktor. Nata atau selulosa bakteri merupakan senyawa yang terdiri dari selulosa murni dan air sehingga dapat dihidrolisis untuk menghasilkan berbagai senyawa degradasi selulosa. Pada penelitian ini diteliti kinetika hidrolisis selulosa bakteri menggunakan katalis natrium hidroksida. Tujuan dari penelitian ini adalah untuk menentukan parameter kinetika reaksi hidrolisis nata menggunakan katalis basa natrium hidroksida. Hasil penelitian menunjukkan bahwa semakin tinggi suhu dan lama waktu hidrolisis akan meningkatkan kinerja reaksi hidrolisis. Kinetika hidrolisis pada penelitian ini terbagi dua tipe yaitu kinetika hidrolisis Tipe 1 yang menggunakan berat basah selulosa bakteri dan dan Tipe 2 yang menggunakan berat kering selulosa bakteri. Dari hasil perhitungan diperoleh orde reaksi hidrolisis selulosa bakteri berkisar antar 5 – 6 dengan konstanta reaksi kinetika hidrolisis Tipe 1 pada suhu 40oC, 60oC dan 80oC berturut – turut adalah 0,000012; 40.255,4; dan 299.839 min-1. Sedangkan konstanta reaksi kinetika hidrolisis Tipe 2 pada suhu 40oC, 60oC dan 80oC berturut – turut adalah 0,516851; 1,124119; dan 2,408972 min-1. Energi aktivasi kinetika hidrolisis Tipe 1 sebesar 558,3932 kJ/mol, dan energi aktivasi kinetika hidrolsis Tipe 2 sebesar 35,31205 kJ/mol. Perbedaan nilai parameter kinetika pada Tipe 1 dan 2 akan menjadi acuan dalam perancangan reaktor hidrolisis nata berbahan baku nata basah dan kering untuk memproduksi berbagai senyawa degradasi selulosa.
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Yablonsky, Gregory, Daniel Branco, Guy Marin, and Denis Constales. "New Invariant Expressions in Chemical Kinetics." Entropy 22, no. 3 (March 24, 2020): 373. http://dx.doi.org/10.3390/e22030373.
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This paper presents a review of our original results obtained during the last decade. These results have been found theoretically for classical mass-action-law models of chemical kinetics and justified experimentally. In contrast with the traditional invariances, they relate to a special battery of kinetic experiments, not a single experiment. Two types of invariances are distinguished and described in detail: thermodynamic invariants, i.e., special combinations of kinetic dependences that yield the equilibrium constants, or simple functions of the equilibrium constants; and “mixed” kinetico-thermodynamic invariances, functions both of equilibrium constants and non-thermodynamic ratios of kinetic coefficients.
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Wulan, Praswasti Pembangun Dyah Kencana, Widodo Wahyu Purwanto, and Yuswan Muharam. "KINETIKA MIKRO DEKOMPOSISI METANA MENJADI KARBON NANOTUBE PADA PERMUKAAN KATALIS Ni-Cu-Al." Reaktor 13, no. 3 (June 3, 2011): 148. http://dx.doi.org/10.14710/reaktor.13.3.148-154.
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MICRO KINETICS OF DECOMPOSITION OF METHANE TO CARBON NANOTUBES OVER NI-CU-AL CATALYST. The main focus of this research was to obtain micro kinetics decomposition of methane producing carbon nanotube on the surface of the Ni-Cu-Al catalyst. Experimental kinetics data collected at a temperature range of 650-750oC and pressure of one atmosphere. The preliminary test was conducted to obtain the kinetics are not influenced by external and internal diffusion limitations as well as inter-phase transfer. Kinetics data were tested by micro kinetic model derived from the catalyst surface reaction mechanism. The most appropriate kinetic model becomes the rate-limiting step of methane decomposition reaction. Results of preliminary experiment showed that the kinetics of the external diffusion effect is negligible at flow rates above 150 mL/min. Internal diffusion can be ignored with a catalyst under 0.25 mm in diameter with a weight of 0.04 grams of catalyst and contact time 2.5x10-4. Rate equation analysis shows that the rate-limiting step is the adsorption which indicates that intermediate consumption (CH4I + I Û CH3I + HI) is faster than the formation of intermediate (adsorption of methane, CH4 + I Û CH4I). The activation energy obtained for 34.628 kJ/mol and pre-exponential factor of 6.583x106. Fokus utama penelitian ini adalah memperoleh kinetika mikro dekomposisi metana yang menghasilkan Carbon Nanotube pada permukaan katalis Ni-Cu-Al. Data kinetika eksperimen diambil pada rentang temperatur 650-750oC dan tekanan 1 atmosfer. Percobaan pendahuluan dilakukan untuk memperoleh daerah kinetika yang tidak dipengaruhi oleh limitasi difusi eksternal dan internal serta perpindahan antar fasa. Data kinetika diuji dengan model kinetika mikro yang diturunkan dari mekanisme reaksi permukaan katalis. Model kinetika yang paling sesuai menjadi tahap pembatas laju reaksi dekomposisi metana. Hasil percobaan pendahuluan kinetika menunjukkan bahwa pengaruh difusi eksternal dapat diabaikan pada laju alir di atas 150 mL/menit. Difusi internal dapat diabaikan dengan menggunakan katalis berdiameter di bawah 0,25 mm dengan berat katalis 0,04 gram pada waktu kontak 2,5x10-4. Analisis persamaan laju menunjukkan bahwa tahap pembatas laju adalah tahap adsorpsi yang menunjukkan bahwa konsumsi intermediate (CH4I + I Û CH3I + HI) lebih cepat dari pembentukan intermediate (adsorpsi metana,CH4 + I Û CH4I). Energi aktivasi yang diperoleh sebesar 34,628 kJ/mol dan faktor pre-eksponensial 6,583x106.
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Wulan, Praswasti PDK, Widodo W. Purwanto, Yuswan Muharam, and Anindya Adiwardhana. "Parameter kinetika reaksi dekomposisi katalitik metana menjadi karbon nanotube dengan katalis Ni-Cu-Al." Jurnal Teknik Kimia Indonesia 11, no. 1 (October 2, 2018): 34. http://dx.doi.org/10.5614/jtki.2012.11.1.5.
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Kinetic Parameter of Methane catalytic Decomposition Reaction into Nanotube Carbon with Ni-Cu-Al Catalyst. Development of production technology of nanotubes carbon through catalytic conversion of hydrocarbons will be efficient and effective if based on knowledge of the nucleation and growth mechanism of carbon nanotubes. Most of the research that focused on identifying the main products of reaction and estimate the activation energy. Growth kinetics and mechanism data of carbon nanotubes not completely available, so that process kinetics models are always based on experimental kinetic data. The objective of this research is to obtain kinetic parameters of catalytic decomposition of methane using the catalyst Ni-Cu-Al with composition of 2:1:1 which was prepared by co-precipitation method using natrium carbonate solution precipitant. Experimental kinetic data were taken in the temperature range of 650-750 °C and pressure of 1 atmosphere. Kinetic data were tested by micro-kinetic model derived from the catalytic surface reaction mechanism. The most appropriate kinetic model with experimental result is the adsorption stage which shows that consumption of intermediate (reaction surface) faster than the formation of intermediate (adsorption of methane). Kinetic parameters obtained are activation energy of 40,6 kJ/mole and pre-exponential factor of 8,625 x 106. Keywords: methane decomposition, hydrogen, carbon nanotubes, co-precipitation, kinetics of reactionAbstrak Pengembangan teknologi produksi karbon nanotube melalui konversi katalitik hidrokarbon akan efisien dan efektif jika didasarkan pada pengetahuan mekanisme nukleasi dan pertumbuhan karbon nanotube. Sebagian besar studi melakukan riset yang difokuskan pada identifikasi produk utama reaksi dan estimasi energi aktivasi. Data kinetika dan mekanisme pertumbuhan karbon nanotube tidak tersedia dengan lengkap sehingga model kinetika proses selalu didasarkan pada data kinetika eksperimen. Pada penelitian ini, dilakukan studi untuk memperoleh parameter kinetika reaksi dekomposisi katalitik metana menggunakan katalis Ni-Cu-Al dengan target komposisi 2:1:1 yang dipreparasi dengan metode kopresipitasi menggunakan presipitan larutan natrium karbonat. Data kinetika eksperimen diambil pada rentang temperatur 650-750 oC dan tekanan 1 atmosfer. Data kinetika diuji dengan model kinetika mikro yang diturunkan dari mekanisme reaksi permukaan katalis. Model kinetika yang paling sesuai dengan hasil percobaan adalah tahap adsorpsi yang menunjukkan bahwa konsumsi intermediate (reaksi permukaan) lebih cepat dari pembentukan intermediate (adsorpsi metana). Parameter kinetika yang diperoleh berupa Energi aktivasi sebesar 40,6 kJ/mol dan faktor pre-eksponensial 8,625 x 106.Kata kunci: dekomposisi metana, hidrogen, karbon nanotube, kopresipitasi, kinetika reaksi
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Hassan, Siti Roshayu, Yung-Tse Hung, Irvan Dahlan, and Hamidi Abdul Aziz. "Kinetic Study of the Anaerobic Digestion of Recycled Paper Mill Effluent (RPME) by Using a Novel Modified Anaerobic Hybrid Baffled (MAHB) Reactor." Water 14, no. 3 (January 27, 2022): 390. http://dx.doi.org/10.3390/w14030390.
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The process kinetics of an anaerobic digestion process for treating recycled paper mill effluent (RPME) was investigated. A laboratory-scale modified anaerobic hybrid baffled reactor (MAHB) was operated at hydraulic retention times of 1, 3, 5, and 7 days, and the results were analyzed for the kinetic models. A kinetic study was conducted by examining the phase kinetics of the anaerobic digestion process, which were divided into three main stages: hydrolysis kinetics, acetogenesis kinetics, and methane production kinetics. The study demonstrated that hydrolysis was the rate-limiting step. The applied Monod and Contois kinetic models showed satisfactory prediction with μmax values of 1.476 and 0.6796 L day−1, respectively.
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Mulokozi, Adolf M. "Kinetic parameters in heterogeneous kinetics." Thermochimica Acta 197, no. 2 (March 1992): 363–72. http://dx.doi.org/10.1016/0040-6031(92)85036-u.
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Zhong, Wei, and Zhou Tian. "Application of Genetic Algorithm in Chemical Reaction Kinetics." Applied Mechanics and Materials 79 (July 2011): 71–76. http://dx.doi.org/10.4028/www.scientific.net/amm.79.71.
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In this paper, a summary of Genetic Algorithm methods developed recent years applied in chemical reaction kinetics was presented. The applications of the Genetic Algorithm in reduction of the chemical reaction kinetics, estimation of the chemical kinetic parameters and calculation of the chemical kinetic equations were expounded here. Eventually, the confronted problem and developing trend of the application of Genetic Algorithm methods in chemical kinetics were reviewed.
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Juliastuti, S. R., J. Baeyens, C. Creemers, and J. Degreve. "Determination of rate parameter for kinetics of nitrification." Jurnal Teknik Kimia Indonesia 4, no. 2 (October 2, 2018): 234. http://dx.doi.org/10.5614/jtki.2005.4.2.7.
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Determination of rate parameter for kinetics of nitrification The nitrification process is the bottleneck step in the total nitrogen removal. The formation of nitrate is considered as the rate limiting step in the whole process and its kinetics determine the design of the nitrification reactor. Heavy metals (Zn2+ and Cu2+) and different organic compounds are used as micropollutants. These kinetics were experimentally measured by respirometry. In line with the aim of the paper, the experimental investigation are conducted to develop design equations to describe kinetic rate relationships under optimum conditions, study the parameter influence such as pH and inhibition by reaction intermediates and inhibition by external pollutants. Results demonstrate that the maximum value of the specific growth rate of autotrophic biomass() is 1.02 day at pH=7 and decreases at pH 7.5; inhibition occurs at substrate (NH4) concentrations in excess of 15 mg N/l; inhibition occurs at increasing concentrations of NO –N and Cu2+ has more pronounced inhibitory effect than Zn2+. The inhibitory effect of organic compounds are listed as the Chlorobenzene > Trichloroethylene> Phenol> Ethyl benzene; the experimental oxygen uptake rate (OUR)-test results the autotrophic kinetic parameter values, which can be used in design equations. Keywords: Respirometry, Autotrophic Biomass, Nitrification, Oxygen Uptake Rate Abstrak Proses nitrifikasi merupakan langkah penting pada penurunan kadar total nitrogen. Pembentukan nitrat dianggap sebagai tahap pembatas kecepatan reaksi pada keseluruhan proses dan kinetikanya menentukan perancangan dari bagian proses nitrifikasi. Logam berat (Zn2+ dan Cu2+) dan berbagai jenis komponen organik digunakan sebagai mikropolutan. Kinetika ini secara eksperimental diukur menggunakan respirometer. Tujuan penelitian adalah mengembangkan persamaan perancangan yang menggambarkan hubungan laju kinetika pada kondisi optimum, studi pengaruh parameter seperti pH, inhibisi karena reaksi intermediat, dan inhibisi oleh polutan dari luar. Hasil penelitian ditunjukkan sebagai berikut: harga laju pertumbuhan biomasa autotrof maksimum spesifik adalah 1,02 hari-1 pada pH=7 dan menurun pada pH 7,5; inhibisi terjadi pada konsentrasi substrat (NH4+) lebih besar dari 15 mg N/l; inhibisi terjadi pada peningkatan konsentrasi NO -N ;Cu2+ lebih dikenal sebagai penyebab inhibisi daripada Zn2+. Efek inhibisi dari komponen organik di daftar mulai dari Chlorobenzene sampai Ethylbenzen. Tes OUR menghasilkan harga parameter kinetika yang dapat dipakai pad apersamaan perencanaan lumpur aktif nitrifikasi. Kata Kunci: Respirometer, BiomasaAutotrof, Nitrifikasi, Laju Kenaikan Oksigen
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Wentzel, M. C., G. A. Ekama, and G. v. R. Marais. "Processes and Modelling of Nitrification Denitrification Biological Excess Phosphorus Removal Systems – A Review." Water Science and Technology 25, no. 6 (March 1, 1992): 59–82. http://dx.doi.org/10.2166/wst.1992.0114.
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This paper reviews developments in modelling the kinetics of activated sludge systems: Completely aerobic nitrification, anoxic/aerobic nitrification denitrification (ND), and anaerobic/anoxic/aerobic nitrification denitrification biological excess phosphorus removal (NDBEPR) systems. The paper highlights the progress in developing a general NDBEPR activated sludge kinetic model – development of polyP organism enhanced cultures, their kinetics, simplification of the kinetics for enhanced cultures under constant flow and load conditions, extension of the simplified model to mixed culture NDBEPR systems under constant flow and load conditions, integration of the polyP organism enhanced culture kinetics with the ND kinetics to give a general NDBEPR kinetic model for cyclic flow and load which incorporates the increased specific denitrification rates observed in NDBEPR systems compared to ND systems. Areas of research that require attention to complete the development of the general NDBEPR kinetic model are identified – denitrification by polyP organisms, calibration and verification of the model for cyclic flow and load, etc.
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Liu, Zu Lan, Lan Qian Li, Yi Ping Liu, and Ming Lu. "Kinetic Study of the Adsorption of Dye onto Cotton in SDS-CTAB Reverse Micelles." Applied Mechanics and Materials 723 (January 2015): 591–95. http://dx.doi.org/10.4028/www.scientific.net/amm.723.591.
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Adsorption kinetic study of C.I. reactive blue 19 onto cotton was carried out in SDS-CTAB reverse micelles. The data of adsorption kinetics were examined using pseudo first-and second-order kinetic models. It was found that the adsorption kinetics of dye on cotton with diffusion controlling follows the pseudo first-order kinetic model.
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Pavlostathis, S. G., and E. Giraldo-Gomez. "Kinetics of Anaerobic Treatment." Water Science and Technology 24, no. 8 (October 1, 1991): 35–59. http://dx.doi.org/10.2166/wst.1991.0217.
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A review of the kinetics of anaerobic treatment and the reported values of such kinetic parameters as the maximum specific substrate utilization rate (k), the half-saturation constant (Ks), the microbial growth yield (Y), and the microorganism decay rate constant (b) are presented. The available kinetic information is presented for each subprocess: (a) hydrolysis of complex, paniculate organic materials; (b) fermentation of amino acids and sugars; (c) anaerobic oxidation of long-chain fatty acids and alcohols; (d) anaerobic oxidation of intermediary products (such as short-chain fatty acids); (e) homoacetogenesis; and (f) methanogenesis. The intrinsic rates of each step as well as mass transfer limitations and their effect on the intrinsic kinetics are discussed and areas requiring further research are also identified. Substantial variation exists in the reported values of the kinetic coefficients. This variation is due in part to the variability in mode of operation, environmental and operational conditions in the various studies as well as to the lack of a widely accepted standard procedure for measuring and expressing the biokinetic coefficients. The hydrolysis step is usually assumed to follow first-order kinetics. Whenever the kinetics of the hydrolysis step were studied, they were generally found to be the limiting-step in the overall conversion of complex substrates to methane. With the exception of the hydrolysis step, all other subprocesses of anaerobic treatment have been successfully modeled by following Monod kinetics. The Contois and Chen & Hashimoto model has also been used quite extensively to account for the effect of influent substrate concentration on effluent quality. Based on a brief overview of the observed phenomena related to the kinetics of mass transfer in methanogenesis, it is concluded that with but few exceptions, the evidence for the significance of mass transfer effects in the different reactor configurations is circumstantial and, in some cases, contradictory. Our understanding of the kinetics of paniculate substrate removal in biofilms is still incomplete for engineering applications, and more research is necessary.
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Tran, Hai Nguyen. "Differences between Chemical Reaction Kinetics and Adsorption Kinetics: Fundamentals and Discussion." Journal of Technical Education Science, no. 70B (June 28, 2022): 33–47. http://dx.doi.org/10.54644/jte.70b.2022.1154.
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Adsorption kinetics is an essential part in adsorption studies. The pseudo-first-order (PFO) and pseudo-second-order (PSO) models are frequently used to model the experimental dataset of time-dependent adsorption. The differential equations (based on reaction rate and rate law) of the PFO and PSO models are similar to those of chemical reactions (i.e., first and second order-kinetic reactions). The adsorption kinetics is illustrated through the plot of qt (the amount of adsorbate adsorbed by adsorbent at time t) vs. time. This plot includes two important regions (kinetic and equilibrium). The adsorption rate constant (k1(PFO) or k2(PSO), respectively) of the PFO or PSO models needs to be calculated from two regions. The appropriate selection of initial adsorbate concentrations for studying adsorption kinetics should be based on adsorption isotherm to ensure that adsorption sites in adsorbent (material) are highly (nearly fully) covered by adsorbate (solute). Only in this case, the rate constant of the adsorption is accurately obtained.
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Lin, Yen-Hui. "Kinetic Study of 4-Chlorophenol Biodegradation by Acclimated Sludge in a Packed Bed Reactor." Processes 10, no. 10 (October 19, 2022): 2130. http://dx.doi.org/10.3390/pr10102130.
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In this study, batch experiments were conducted to evaluate the degradation of 4-CP using acclimated sludge. The Monod and Haldane models were employed to fit the specific growth rate with various initial 4-CP concentrations of 67–412 mg/L in the batch experiments. Haldane kinetics showed a better fit to experimental results than Monod kinetics. The kinetic parameters were obtained from a comparison of Monod and Haldane kinetics with batch experimental data. The values of μm and KS were found to be 0.691 d−1 and 5.62 mg/L, respectively, for Monod kinetics. In contrast, the values of μm, KS, and KI were 1.30 d−1, 8.38 mg/L, and 279.4 mg/L, respectively, for Haldane kinetics. The kinetic parameters in Haldane kinetics were used as input parameters for the kinetic model system of the packed bed reactor (PBR). The continuous flow PBR was conducted to validate the kinetic model system. The model-simulated results agreed well with experimental data in the PBR performance operation. At the steady-state stage, the removal efficiency of 4-CP was 70.8–96.1%, while the hydraulic retention time (HRT) was 2.5 to 12.4 h. The corresponding removal of 4-CP was assessed to be 94.6 and 96.1% when the inlet 4-CP loading rate was increased from 0.11 to 0.51 kg/m3-d. The approaches of kinetic models and experiments presented in this study can be applied to design a PBR for 4-CP treatment in wastewater from the effluents of various industries.
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Yen, Shih-Wei, Wei-Hsin Chen, Jo-Shu Chang, Chun-Fong Eng, Salman Raza Naqvi, and Pau Loke Show. "Torrefaction Thermogravimetric Analysis and Kinetics of Sorghum Distilled Residue for Sustainable Fuel Production." Sustainability 13, no. 8 (April 11, 2021): 4246. http://dx.doi.org/10.3390/su13084246.
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This study investigated the kinetics of isothermal torrefaction of sorghum distilled residue (SDR), the main byproduct of the sorghum liquor-making process. The samples chosen were torrefied isothermally at five different temperatures under a nitrogen atmosphere in a thermogravimetric analyzer. Afterward, two different kinetic methods, the traditional model-free approach, and a two-step parallel reaction (TPR) kinetic model, were used to obtain the torrefaction kinetics of SDR. With the acquired 92–97% fit quality, which is the degree of similarity between calculated and real torrefaction curves, the traditional method approached using the Arrhenius equation showed a poor ability on kinetics prediction, whereas the TPR kinetic model optimized by the particle swarm optimization (PSO) algorithm showed that all the fit qualities are as high as 99%. The results suggest that PSO can simulate the actual torrefaction kinetics more accurately than the traditional kinetics approach. Moreover, the PSO method can be further employed for simulating the weight changes of reaction intermediates throughout the process. This computational method could be used as a powerful tool for industrial design and optimization in the biochar manufacturing process.
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Setiawan, Adhi, W. Widiyastuti, Sugeng Winardi, and Agung Nugroho. "KINETIKA REAKSI SINTHESIS BIOMATERIAL HIDROXYAPATITE DENGAN JENIS PREKURSOR NITRAT DAN ASETAT." Reaktor 15, no. 2 (February 20, 2014): 104. http://dx.doi.org/10.14710/reaktor.15.2.104-110.
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Hidroxyapatite (HAp) merupakan salah satu biomaterial yang banyak diaplikasikan dalam dunia medis untuk membuat implant jaringan tubuh terutama tulang dan gigi sehingga kemurnian produk HAp memegang peranan yang cukup penting. Agar diperoleh HAp dengan kemurnian tinggi, kinetika reaksi pembentukan HAp harus diketahui secara jelas. Metode yang digunakan untuk memperoleh kinetika reaksi HAp adalah dengan analisis TG-DTA yang dilakukan pada dua jenis prekursor HAp yaitu asetat dan nitrat. Metode TG-DTA tersebut dilakukan dengan memanaskan prekursor HAp dengan variasi laju pemanasan 10, 15, 17, dan 20 oC/menit. Hasil analisis TG-DTA menunjukkan bahwa reaksi dekomposisi prekursor asetat dan nitrat membentuk HAp masing-masing terjadi pada suhu 659 oC dan 560 oC. Hasil fitting parameter kinetika menunjukkan bahwa energi aktivasi pembentukan HAp pada prekursor asetat sebesar 161,56 kJ/mol dengan model kinetika Normal Grain Growth sedangkan pada prekursor nitrat sebesar 374 kJ/mol dengan model kinetika Johnson-Mehl-Avrami. Kata kunci: Biomaterial, hidroxypapatite, Dekomposisi, Energi Aktivasi ABSTRACT KINETIC STUDY OF THE BIOMATERIAS HIDOXYAPATITE SINTHESIS WITH PRECURSOR NITRATE AND ACETATE. Hidroxyapatite (HAp) is one of the biomaterials widely applied in the medical world to make implant tissues of the body, especially bones and teeth so that the purity of the HAp plays a fairly important. In order to obtain high purity HAp, reaction kinetics should be known clearly. TG-DTA is method used to obtain the reaction kinetics of HAp.TG-DTA analyzes were conducted on precursors acetate and nitrate. TG-DTA method is carried out by heating HAp precursor with variation heating rate 10, 15, 17, and 20° C/min respectively. The results of TG-DTA showed decomposition precursor acetate and nitrate formed HAp occurs on temperature 659° C and 560° C respectively. The results of the fitting kinetic showed activation energy of the HAp formation on acetate precursors about 161.56 kJ/mol with Normal Grain Growth kinetic model whereas the nitrate precursor about 374 kJ/mol with Johnson-Mehl-Avrami kinetic model.
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Moses, Julianne I. "Chemical kinetics on extrasolar planets." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, no. 2014 (April 28, 2014): 20130073. http://dx.doi.org/10.1098/rsta.2013.0073.
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Chemical kinetics plays an important role in controlling the atmospheric composition of all planetary atmospheres, including those of extrasolar planets. For the hottest exoplanets, the composition can closely follow thermochemical-equilibrium predictions, at least in the visible and infrared photosphere at dayside (eclipse) conditions. However, for atmospheric temperatures , and in the uppermost atmosphere at any temperature, chemical kinetics matters. The two key mechanisms by which kinetic processes drive an exoplanet atmosphere out of equilibrium are photochemistry and transport-induced quenching. I review these disequilibrium processes in detail, discuss observational consequences and examine some of the current evidence for kinetic processes on extrasolar planets.
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Chan, T. W., G. D. Shyu, and A. I. Isayev. "Reduced Time Approach to Curing Kinetics, Part I: Dynamic Rate and Master Curve from Isothermal Data." Rubber Chemistry and Technology 66, no. 5 (November 1, 1993): 849–64. http://dx.doi.org/10.5254/1.3538349.
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Abstract A reduced time approach has been used to predict nonisothermal curing kinetics based on isothermal kinetic data. This approach makes it clear that the conversion in a kinetic process is a function of the reduced time alone and allows for the construction of a master curve from isothermal kinetic data, indicating that the dynamic (or nonisothermal ) rate is equal to the isothermal rate. The approach can be applied to curing, crystallization, and other physico-chemical kinetics. A method is also described for correcting the nonisothermal curing kinetic data obtained from differential scanning calorimetry ( DSC ) for a temperature lag between the sample and the DSC furnace. For two rubber compounds, it has been found that the nonisothermal curing kinetic data corrected for this temperature lag are in better agreement with the predictions based on isothermal kinetics than the uncorrected data.
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Liavitskaya, Tatsiana, and Sergey Vyazovkin. "All You Need to Know about the Kinetics of Thermally Stimulated Reactions Occurring on Cooling." Molecules 24, no. 10 (May 18, 2019): 1918. http://dx.doi.org/10.3390/molecules24101918.
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In this tutorial overview article the authors share their original experience in studying the kinetics of thermally stimulated reactions under the conditions of continuous cooling. It is stressed that the kinetics measured on heating is similar to that measured on cooling only for single-step reactions. For multi-step reactions the respective kinetics can differ dramatically. The application of an isoconversional method to thermogravimetry (TGA) or differential scanning calorimetry (DSC) data allows one to recognize multi-step kinetics in the form of the activation energy that varies with conversion. Authors’ argument is supported by theoretical considerations as well as by experimental examples that include the reactions of thermal decomposition and crosslinking polymerization (curing). The observed differences in the kinetics measured on heating and cooling ultimately manifest themselves in the Arrhenius plots of the opposite curvatures, which means that the heating kinetics cannot be used to predict the kinetics on cooling. The article provides important background knowledge necessary for conducting successful kinetic studies on cooling. It includes a practical advice on optimizing the parameters of cooling experiments as well as on proper usage of kinetic methods for analysis of obtained data.
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Kovárová-Kovar, Karin, and Thomas Egli. "Growth Kinetics of Suspended Microbial Cells: From Single-Substrate-Controlled Growth to Mixed-Substrate Kinetics." Microbiology and Molecular Biology Reviews 62, no. 3 (September 1, 1998): 646–66. http://dx.doi.org/10.1128/mmbr.62.3.646-666.1998.
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SUMMARY Growth kinetics, i.e., the relationship between specific growth rate and the concentration of a substrate, is one of the basic tools in microbiology. However, despite more than half a century of research, many fundamental questions about the validity and application of growth kinetics as observed in the laboratory to environmental growth conditions are still unanswered. For pure cultures growing with single substrates, enormous inconsistencies exist in the growth kinetic data reported. The low quality of experimental data has so far hampered the comparison and validation of the different growth models proposed, and only recently have data collected from nutrient-controlled chemostat cultures allowed us to compare different kinetic models on a statistical basis. The problems are mainly due to (i) the analytical difficulty in measuring substrates at growth-controlling concentrations and (ii) the fact that during a kinetic experiment, particularly in batch systems, microorganisms alter their kinetic properties because of adaptation to the changing environment. For example, for Escherichia coli growing with glucose, a physiological long-term adaptation results in a change in KS for glucose from some 5 mg liter−1 to ca. 30 μg liter−1. The data suggest that a dilemma exists, namely, that either “intrinsic” KS (under substrate-controlled conditions in chemostat culture) or μmax (under substrate-excess conditions in batch culture) can be measured but both cannot be determined at the same time. The above-described conventional growth kinetics derived from single-substrate-controlled laboratory experiments have invariably been used for describing both growth and substrate utilization in ecosystems. However, in nature, microbial cells are exposed to a wide spectrum of potential substrates, many of which they utilize simultaneously (in particular carbon sources). The kinetic data available to date for growth of pure cultures in carbon-controlled continuous culture with defined mixtures of two or more carbon sources (including pollutants) clearly demonstrate that simultaneous utilization results in lowered residual steady-state concentrations of all substrates. This should result in a competitive advantage of a cell capable of mixed-substrate growth because it can grow much faster at low substrate concentrations than one would expect from single-substrate kinetics. Additionally, the relevance of the kinetic principles obtained from defined culture systems with single, mixed, or multicomponent substrates to the kinetics of pollutant degradation as it occurs in the presence of alternative carbon sources in complex environmental systems is discussed. The presented overview indicates that many of the environmentally relevant apects in growth kinetics are still waiting to be discovered, established, and exploited.
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Maitra, S., S. Mukherjee, N. Saha, and J. Pramanik. "Non-isothermal decomposition kinetics of magnesite." Cerâmica 53, no. 327 (September 2007): 284–87. http://dx.doi.org/10.1590/s0366-69132007000300011.
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Kinetics of thermal decomposition of Indian magnesite was studied by thermo-gravimetric analysis under non-isothermal condition. Coats and Redfern Integral approximation method was used to determine the kinetic parameters. Using the kinetic parameters different kinetic functions were analyzed with the experimental data to ascertain the decomposition mechanism of magnesium carbonate and it was observed that the decomposition reaction followed a contracting sphere kinetic mechanism.
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Fouad, Mohamed R., Ahmed F. El-Aswad, and Maher I. Aly. "Mathematical models of the adsorption-desorption kinetics of fenitrothion in clay soil and sandy clay loam soil." Current Chemistry Letters 13, no. 4 (2024): 641–54. http://dx.doi.org/10.5267/j.ccl.2024.6.002.
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Batch adsorption and desorption kinetic experiments of fenitrothion on clay soil and sandy clay loam soil indicated that the equilibration time was approximately 30 hours. The kinetics of adsorption and desorption exhibited two distinct stages: a rapid process in the initial stages followed by a slow process. The pseudo-first-order model followed by the Elovich kinetic model fit the experimental adsorption and desorption data quite well, with high values of R2 and low values of ∆qe% and SSE. Accordingly, the pseudo-first-order model is most suitable for describing the adsorption and desorption kinetics of fenitrothion on clay soil and sandy clay soil. Pseudo-second-order model type-1 and type-2 models fit the experimental adsorption data; however, these models cannot be used to describe desorption kinetics. Moreover, the modified Freundlich model has limited applicability, and the intraparticle diffusion kinetic model cannot describe the kinetics of the adsorption and desorption of fenitrothion on clay and sandy clay loam soils.
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Provis, J. L., and J. S. J. van Deventer. "Geopolymerisation kinetics. 2. Reaction kinetic modelling." Chemical Engineering Science 62, no. 9 (May 2007): 2318–29. http://dx.doi.org/10.1016/j.ces.2007.01.028.
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Gao, Han, Xiaotian Zhao, Lei Zhou, Fabrizio Sabba, and George F. Wells. "Differential kinetics of nitrogen oxides reduction leads to elevated nitrous oxide production by a nitrite fed granular denitrifying EBPR bioreactor." Environmental Science: Water Research & Technology 6, no. 4 (2020): 1028–43. http://dx.doi.org/10.1039/c9ew00881k.
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L Salami, DO Olumuyiwa, EA Alfred, and OS Olakanmi. "Kinetic modelling of dumpsite leachate treatment using Musa sapientum peels as bio-sorbent." Global Journal of Engineering and Technology Advances 9, no. 2 (November 30, 2021): 024–31. http://dx.doi.org/10.30574/gjeta.2021.9.2.0117.
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Kinetics models are very vital to dumpsite operators and planners as they provide relevant information for effective treatment of leachates. The aim of this work is to model the kinetic process of treatment of Lagos dumpsite leachate using Musa sapientum peels as bio-sorbent with a view of establishing the kinetic parameters of the treatment process. Musa sapientum peels which were collected from Ayetoro market in Epe Local Government area of Lagos State were used to prepare the bio-sorbent. Kinetic process was carried out using 1 g of the prepared bio-sorbent in 100 ml Lagos dumpsite leachate in different conical flasks and at various contacting time. The kinetic data obtained were fitted to different kinetics models. The kinetics models tested were Fractional power model, Lagregren pseudo first – order model, Pseudo second – order model, Kuo – Lotse kinetic model, Blanchard kinetic model and Elovich kinetic model. Other kinetics models considered were Sobkowsk – Czerwi kinetic model, Intraparticle diffusion (IPD) model, Behnajady – Modirshahla – Ghanbery (BMG) model and Diffusion – Chemisorption model. Coefficient of determination (R2) values and the expected nature of the plots of the models were used to screen the tested models. The results revealed that the Pseudo second – order kinetic model has the best R2 value of 0.99996 and the graph followed the expected nature of the plot hence it was adopted in this work. It was concluded that Pseudo second – order kinetic model can be used to navigate the treatment process of Lagos dumpsite using Musa sapientum peels as bio-sorbent.
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Petkovic, Sandra, Borivoj Adnadjevic, and Jelena Jovanovic. "Novel kinetics model for adsorption of pollutant from wastewaters onto zeolites. Kinetics of phenol adsorption on zeolite-type silicalite." Adsorption Science & Technology 37, no. 3-4 (March 4, 2019): 349–64. http://dx.doi.org/10.1177/0263617419833201.
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The kinetics of isothermal adsorption of phenol from an aqueous solution onto the zeolite-type silicalite was investigated. Zeolite-type silicalite was synthesized and its basic physico-chemical properties were determined. Isothermal adsorption kinetics curves of phenol on zeolite-type silicalite were measured at temperature range from 283 to 313 K. By applying Friedman’s differential isoconversional method it was found that the adsorption of phenol on silicalite has one rate determining step. By using the ‘model-fitting’ method it was established that the kinetic of adsorption can be described with theoretical kinetic model of the two-dimensional phase-boundary controlled reaction (model R2). The kinetic parameters, activation energy ([Formula: see text]) and preexponetial factor ( lnA = 14.1 min−1) of phenol adsorption were calculated. The thermodynamic parameters, standard enthalpy (Δ H*), standard entropy (Δ S*) and standard free Gibbs energy of adsorption (Δ G*) were calculated and discussed. A novel model for the kinetics of pollutant adsorption from wastewaters onto zeolites based on the following: zeolite pores have cylindrical shape with average radius r0, pores in zeolite are filled simultaneously by the model ‘layer by layer’, the rate of phenol adsorption is higher than the rate of the growth of the thickness of the adsorption layer was suggested. It has been found that the adsorption kinetics can be completely described by this kinetic model.
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Rogozhnikov, D. A., and B. V. Kolmachikhin. "Polymetallic Ore Concentration Middlings Nitric Acid Leaching Kinetics." Solid State Phenomena 265 (September 2017): 1065–70. http://dx.doi.org/10.4028/www.scientific.net/ssp.265.1065.
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The purpose of this work is the kinetic evaluation of reactions occurring during nitric acid leaching of pollymetallic sulfide middlings, for the most complete translation of copper, zinc and sulfur in solution and concentration of precious metals in residue. Methodology is pollymetallic sulfide middlings nitric acid leaching kinetics were studied using mathematical methods such as the experimental data numerical differentiation. Relevance/value is the main sulfide minerals kinetic characteristics were obtained for the studied materials, including the rate of the process, order of reaction, the rate constant for the forward and reverse reaction. Findings are the rate of the process is limited by kinetics. The calculated values of kinetic parameters showed that the process kinetics are influenced by such factors as the nature of leachable sulfide, nitric acid concentration, the surface area of the solid sulfide, the system approaches equilibrium at saturation of the liquid phase reaction products.
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Qi, Yu Song, Jian Wen Yang, Zhao Hua Zeng, and Yong Lie Chen. "Study of UV Curing Kinetics for Coating Containing Siloxane Modified Polyurethane-Acrylate." Advanced Materials Research 791-793 (September 2013): 175–78. http://dx.doi.org/10.4028/www.scientific.net/amr.791-793.175.
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The UV curing kinetics of coating containing siloxane modified polyurethane-acrylate were studied using photo-DSC (DPC). The effects of some factors such as incident light intensity, initiator concentration, reaction temperature on the curing kinetics have been analysized from DPC data. The curing kinetic parameters (kp and kt) for prepolymers have also been determinedv by combining steady state and non-steady state kinetics.
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Bakar, Siti Asmah, Hussein Saed Geedi, Mohd Hairul Khamidun, Radin Maya Saphira Radin Mohamed, Mohammad Faizal Che Daud, and Umi Fazara Md Ali. "Evaluation lead removal kinetics modelling of adsorption by using composite of Chitosan and Ceramic waste." IOP Conference Series: Earth and Environmental Science 1205, no. 1 (June 1, 2023): 012010. http://dx.doi.org/10.1088/1755-1315/1205/1/012010.
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Abstract This study focuses on understanding the Pb adsorption kinetics from greywater using a composite of chitosan and ceramic waste (CCCW), which is suitable for preserving water quality. For ease and general application, a kinetic model with a simple expression and a manageable small set of parameters that nevertheless provides a fair adsorption description in the equilibrium state is still critical. Although some current kinetic models, such as the pseudo-second-order type, meet these conditions, their performance is still questionable, especially when applied to a variety of experimental data. Batch adsorption experiments were carried out with the predetermined value of the operational parameter such as adsorbent dosage, contact time, and shaking speed. Kinetic models such as pseudo-first order, pseudo-second order, intraparticle diffusion kinetic model, Avrami model, and the Bangham model were used in this study to understand the kinetics of removal of lead from greywater. The efficacy results of adsorbent’s dose in lead removal process with increasing adsorption capacity with contact time from 0.0014 to 0.00277 mg/g, the removal efficiency increases from 45.90 to 90.83%. The most significant contribution of this work is an understanding of the optimal kinetics model that can describe the behaviour of lead adsorption on CCCW. Five models for the adsorption of Pb2+ have been identified to clarify the kinetics models’ usefulness in accuracy based on rank order. This study may provide insight into understanding the ability and usability of the appropriate model in kinetics adsorption.
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Gajewska, Magdalena, and Katarzyna Skrzypiec. "Kinetics of nitrogen removal processes in constructed wetlands." E3S Web of Conferences 26 (2018): 00001. http://dx.doi.org/10.1051/e3sconf/20182600001.
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The aim of this paper is to present a state-of-the-art review of the kinetics of nitrogen removal in constructed wetlands. Biological processes of nitrogen removal from wastewater can be described using equations and kinetic models. Hence, these kinetic models which have been developed and evaluated allow for predicting the removal of nitrogen in treatment wetlands. One of the most important, first order removal model, which is still applied, was analysed and its rate coefficients and factors were compared. This study also demonstrates the validity of Monod and multiple Monod kinetics, commonly seen today. Finally, a computational example of the reaction kinetics of nitrogen removal was also included in the study.
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Van Praagh, Andrew, Bo Nelson, Paul Ballieu, Melanie Smith, and Mike Rule. "Abstract 7427: Automated, real-time acquisition and quantification of peak, plateau-phase in vivo bioluminescent data." Cancer Research 84, no. 6_Supplement (March 22, 2024): 7427. http://dx.doi.org/10.1158/1538-7445.am2024-7427.
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Abstract It is widely recognized that plateau-phase bioluminescent (BL) kinetic curve data should be used when reporting on BLI results from substrate-injection BLI model systems. The basis for this understanding is that plateau-phase BL data is uniquely suited in several ways: (i) it will optimize the detection of target, luciferase-expressing cells (especially when they are low in copy number or deep within the animal model), (ii) it will optimize BLI data reproducibility (with there being no change in signal values across the plateau phase), and (iii) it will also provide BLI data values that correlate consistently with the number of viable target cells in a given BLI model. Given this critical value of plateau-phase BL data, there is, nevertheless, a simple practical issue to be addressed: The overall manual process of generating BL kinetic curves, and then identifying and quantifying plateau-phase data is not insignificant—it takes time!In this poster, we review the performance of “Kinetics,” a new feature in the Aura software platform from Spectral Instruments Imaging, LLC. Kinetics is designed to collect, present, and analyze BL kinetic curve data for up to 10 mice, in a completely automated and real-time fashion. Data outputs include a live graph that simultaneously presents individual mouse, whole body ROI (Total photon/sec) values vs. time post-luciferase injection, and analogous mean BL values per mouse group. Here in, we present an evaluation of the performance of Kinetics under various testing conditions. We initially evaluated Kinetics’ ability to acquire, present and analyze the BL kinetic curves of 5 phantoms. The photon output rates of these phantoms (Total photons/sec) were programmed to mimic the rise, plateau, and fall sequence typically seen BLI studies. In an analogous fashion, we then tested Kinetics’ ability to acquire, present, and analyze the BL kinetic curves of 5 to 10 live mice from several oncology models. Furthermore, we used Kinetics in oncology efficacy studies to monitor for expected changes in BL kinetic curve shapes (i.e., for changes in the onset times and durations of the rise, plateau and fall phases in BL kinetic curves) between different treatment groups (e.g., between positive controls groups and one or more treatment groups). In the same studies, we also used Kinetics to check for changes in BL kinetic curve shapes that might occur for a given treatment group across several time points, after pathogen challenge. Results from this set of experiments consistently and clearly illustrated the capability of Kinetics to acquire, present and analyze individual and mean BL kinetic curve data for up to 10 mice at a time, in an automated and real-time fashion. We believe that Kinetics from Spectral Instruments Imaging, LLC, has the potential to revolutionize the ease with which plateau-phase, BL kinetic curve data can be collected, presented, and used in a wide range of preclinical BLI studies. Citation Format: Andrew Van Praagh, Bo Nelson, Paul Ballieu, Melanie Smith, Mike Rule. Automated, real-time acquisition and quantification of peak, plateau-phase in vivo bioluminescent data [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7427.
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Christensen, F. R., G. Holm Kristensen, and J. la Cour Jansen. "Biofilm Structure – An Important and Neglected Parameter in Waste Water Treatment." Water Science and Technology 21, no. 8-9 (August 1, 1989): 805–14. http://dx.doi.org/10.2166/wst.1989.0283.
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Experimental investigations on the kinetics of wastewater treatment processes in biofilms were performed in a laboratory reactor. Parallel with the kinetic experiments, the influence of the biofilm kinetics on the biofilm structure was studied at macroscopic and microscopic levels. The close interrelationship between biofilm kinetics and structural changes caused by the kinetics is illustrated by several examples. From the study, it is evident that the traditional modelling of wastewater treatment processes in biofilm reactors based on substrate removal kinetics alone will fail in many cases, due to the inevitable changes in the biofilm structure not taken into consideration. Therefore design rules for substrate removal in biofilms used for wastewater treatment must include correlations between the removal kinetics and the structure and development of the biological film.
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Widjaja, Frances, Yasser Alhejji, and Ivonne M. C. M. Rietjens. "The Role of Kinetics as Key Determinant in Toxicity of Pyrrolizidine Alkaloids and Their N-Oxides." Planta Medica 88, no. 02 (November 5, 2021): 130–43. http://dx.doi.org/10.1055/a-1582-9794.
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AbstractPyrrolizidine alkaloids (PAs) are a large group of plant constituents of which especially the 1,2- unsaturated PAs raise a concern because of their liver toxicity and potential genotoxic carcinogenicity. This toxicity of PAs depends on their kinetics. Differences in absorption, distribution, metabolism, and excretion (ADME) characteristics of PAs may substantially alter the relative toxicity of PAs. As a result, kinetics will also affect relative potency (REP) values. The present review summarizes the current state-of-the art on PA kinetics and resulting consequences for toxicity and illustrates how physiologically-based kinetic (PBK) modelling can be applied to take kinetics into account when defining the relative differences in toxicity between PAs in the in vivo situation. We conclude that toxicokinetics play an important role in the overall toxicity of pyrrolizidine alkaloids. and that kinetics should therefore be considered when defining REP values for combined risk assessment. New approach methodologies (NAMs) can be of use to quantify these kinetic differences between PAs and their N-oxides, thus contributing to the 3Rs (Replacement, Reduction and Refinement) in animal studies.
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Maafi, Mounir, and Wassila Maafi. "Quantification of Unimolecular Photoreaction Kinetics: Determination of Quantum Yields and Development of Actinometers—The Photodegradation Case of Cardiovascular Drug Nisoldipine." International Journal of Photoenergy 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/454895.
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The lack of integrated rate-laws for photoreactions has led to carry out the treatment of drugs photodegradation kinetic data using the classical zeroth-, first-, and second-order kinetics that were originally developed for thermal reactions. The recent developments of Φ-order kinetic models has opened new perspectives in the treatment of photoreaction kinetics of systems involving a photolabile molecule (A) transforming into a photochemically and thermally stable product (B), that is, the AB(1Φ) photoreaction systems. Within this framework, the kinetics of cardiovascular and photosensitive drug nisoldipine (NIS) has been rationalised. Continuous and monochromatic irradiation of NIS in ethanol obeyed Φ-order kinetics with a sigmoid-shaped quantum yield variation with irradiation wavelength (0.0041–0.35 within 235–390 nm spectral region). Both NIS initial concentration-induced self-photostabilisation effect and the photostabilisation by absorption competitors were quantified (up 70%) and related to a reduction of the photokinetic factor. Finally, the Φ-order kinetics also served to demonstrate the actinometric potential of NIS for the 320–400 nm dynamic range.
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Fatmawati, Akbarningrum. "Model kinetika inhibisi substrat pada pertumbuhan Kluyveromyces lactis." Jurnal Teknik Kimia Indonesia 8, no. 2 (October 2, 2018): 50. http://dx.doi.org/10.5614/jtki.2009.8.2.3.
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Substrat inhibition kinetic model of Kluyveromyces lactis growthFood industry waste such as whey may be utilized as substrates in fermentation processes. Kluyveromyces lactis is yeast that can metabolize the lactose content of whey. In fermentation process design, the kinetics data and growth model of the microorganism are essential. This research was done to identify the growth kinetic model of Kluyveromyces lactis FNCC 3024 in lactose, glucose, and galactose substrates. Substrate concentration was varied as 5, 10, 20, 50, 100, and 150 g/L. Yeast growth profile in glucose and lactose substrates indicated substrate inhibition effect, while the growth profile in galactose substrate did not. Non-competitive substrate inhibition kinetic model was more suitable for glucose and lactose models, with a relatively small sum of squares of errors, namely 9.956 x 10-3 for glucose and 3.777 x 10-3 for lactose. Monod kinetic model for galactose substrate produced the lowest sum of squares of errors, namely 1.358 x 10-3. The maximum specific growth rate obtained from the modeling for glucose, lactose, and galactose substrates were 0.295, 0.265, and 0.147 hour-1.Keywords: kinetics, growth, inhibition, substrate, Kluyveromyces lactis Abstrak Limbah industri makanan seperti whey dapat dimanfaatkan sebagai substrat dalam proses fermentasi. Kluyveromyces lactis adalah salah satu ragi yang dapat memetabolisme kandungan laktosa dari whey. Pada perancangan proses fermentasi sangat diperlukan data kinetika dan model pertumbuhan dari mikroorganisme. Penelitian ini dilakukan untuk mengetahui model kinetika pertumbuhan batch Kluyveromyces lactis FNCC 3024 pada substrat laktosa, glukosa dan galaktosa. Konsentrasi substrat divariasi sebesar 5, 10, 20, 50, 100 dan 150 g/L. Profil pertumbuhan ragi pada substrat glukosa dan laktosa menunjukkan adanya inhibisi substrat sedangkan profil pertumbuhan pada substrat galaktosa inhibisi substrat tidak tampak. Model kinetika inhibisi subtrat non-kompetitif lebih tepat digunakan untuk substrat glukosa dan laktosa dengan kuadrat beda yang cukup kecil yaitu 9,956 x 10-3 untuk glukosa dan 3,777 x 10-3 untuk laktosa. Model kinetika Monod untuk substrat galaktosa memberikan jumlah kuadrat residual terkecil yaitu 1,358 x 10-3. Laju pertumbuhan spesifik maksimum yang dihasilkan dan pemodelan untuk substrat glukosa, laktosa dan galaktosa berturut-turut adalah 0,295, 0,265 dan 0,147 jam-1.Kata kunci : kinetika, pertumbuhan, inhibisi, substrat, Kuyveromyces lactis
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Constales, Denis, Gregory Yablonsky, Yiming Xi, and Guy Marin. "Egalitarian Kinetic Models: Concepts and Results." Energies 14, no. 21 (November 2, 2021): 7230. http://dx.doi.org/10.3390/en14217230.
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In this paper, two main ideas of chemical kinetics are distinguished, i.e., a hierarchy and commensuration. A new class of chemical kinetic models is proposed and defined, i.e., egalitarian kinetic models (EKM). Contrary to hierarchical kinetic models (HKM), for the models of the EKM class, all kinetic coefficients are equal. Analysis of EKM models for some complex chemical reactions is performed for sequences of irreversible reactions. Analytic expressions for acyclic and cyclic mechanisms of egalitarian kinetics are obtained. Perspectives on the application of egalitarian models for reversible reactions are discussed. All analytical results are illustrated by examples.
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Basheer Hasan, Diya'uddeen, Abdul Aziz Abdul Raman, and Wan Mohd Ashri Wan Daud. "Kinetic Modeling of a Heterogeneous Fenton Oxidative Treatment of Petroleum Refining Wastewater." Scientific World Journal 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/252491.
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The mineralisation kinetics of petroleum refinery effluent (PRE) by Fenton oxidation were evaluated. Within the ambit of the experimental data generated, first-order kinetic model (FKM), generalised lumped kinetic model (GLKM), and generalized kinetic model (GKM) were tested. The obtained apparent kinetic rate constants for the initial oxidation step (k2′), their final oxidation step (k1′), and the direct conversion to endproducts step (k3′) were 10.12, 3.78, and 0.24 min−1for GKM; 0.98, 0.98, and nil min−1for GLKM; and nil, nil, and >0.005 min−1for FKM. The findings showed that GKM is superior in estimating the mineralization kinetics.
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Yao, Hui Min, Jun Yi Zhu, and Guang Qing Xia. "The Drug Loading Kinetics Mechanism of Ion Exchange Fiber as a Novel Kind of Drug Carrier Material." Advanced Materials Research 904 (March 2014): 54–58. http://dx.doi.org/10.4028/www.scientific.net/amr.904.54.
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The adsorption of Fenazoxine hydrochloride was investigated by performing batch kinetic sorption experiments. Experiments were carried out as function of contact time, initial concentration. Adsorption data were modeled using the pseudo-first-order and pseudo-second-order kinetics equations. It showed that the pseudo-second order kinetic equation can describe the adsorption kinetics best. The results indicate that ion-exchange fiber is suitable as drug carriers for loading drugs.
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Sambhi, M. S. "Kinetics of Chain Scission of Natural Rubber." Rubber Chemistry and Technology 62, no. 5 (November 1, 1989): 779–87. http://dx.doi.org/10.5254/1.3536274.
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Abstract The first-order and zero-order kinetic models of chain scission, based on random chain scission processes, are critically examined. It is likely that for many practical situations, the first-order chain scission kinetics can be represented by pseudozero-order kinetic types of equations. The kinetic results indicate that chain scission of NR occurs either by a pseudofirst-order or a pseudozero-order process. The pseudozero-order chain scission kinetics of NR are in consonance with the result that chain scission involves the bimolecular reaction of peroxy radicals in the termination step of the oxidation mechanism. However, this does not preclude unambiguously other chain scission reactions. The chain scission activation energy of NR is determined with the use of expressions derived for the oxidative degradation of NR as measured in terms of Wallace plasticities.
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Vidal, Eduardo, Antonio Negro, Alberto Cassano, and Cristina Zalazar. "Simplified reaction kinetics, models and experiments for glyphosate degradation in water by the UV/H2O2process." Photochemical & Photobiological Sciences 14, no. 2 (2015): 366–77. http://dx.doi.org/10.1039/c4pp00248b.
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This work reports the degradation kinetics of glyphosate in water employing the UV/H2O2process. The kinetic model was experimentally validated. Results compare the kinetics of the herbicide alone and a commercial formulation.
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Morasch, Robert, Hubert A. Gasteiger, and Bharatkumar Suthar. "Li-Ion Battery Active Material Impedance Analysis I: Comparison of Measured NCM 111 Kinetics with Butler-Volmer Equation Based Predictions." Journal of The Electrochemical Society 170, no. 8 (August 1, 2023): 080522. http://dx.doi.org/10.1149/1945-7111/acf161.
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The expression for the exchange current density to describe the intercalation kinetics of Li-ion battery materials proposed by Newman and coworkers has been used extensively for battery modeling, however its applicability to existing battery materials should be validated. Here we show an electrochemical impedance spectroscopy (EIS) analysis of the kinetic behavior of NCM 111 as a function of electrolyte salt concentration and state-of-charge (SOC) and compare it to the proposed theory. An areal capacity dependent EIS analysis first gives insights into the feasibility of measuring kinetic and transport parameters, including the solid diffusion resistance of lithium, showing that low-areal capacity electrodes are required to predominantly probe the kinetics. We then show how the charge transfer kinetics follow a Butler-Volmer type concentration dependent behavior for lower concentrated electrolytes (≤1.5 M) but deviate from the proposed theory at higher salt concentrations. A further SOC dependent analysis shows how NCM 111 generally follows the proposed theory of U-shaped symmetric kinetics, but the limited oxidative stability window leads to practically asymmetric kinetics for charging and discharging. This asymmetry is visible in NCM 111 lithiation and delithiation rate tests, where upon lithiation the kinetics generally become slower for higher degrees of lithiation, limiting the performance.
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KITIS, G., C. FURETTA, and V. PAGONIS. "MIXED-ORDER KINETICS MODEL FOR OPTICALLY STIMULATED LUMINESCENCE." Modern Physics Letters B 23, no. 27 (October 30, 2009): 3191–207. http://dx.doi.org/10.1142/s0217984909021351.
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The theory of mixed-order kinetics is well-established for the description of single thermoluminescence (TL) glow-peaks. The main advantage of mixed-order kinetics relative to the more widely used general-order kinetic theory is that the former is physically meaningful whereas the latter is entirely empirical. In the case of optically stimulated luminescence (OSL) either non-first-order or second-order kinetics are studied using the empirical general-order kinetics theory. In the present work, expressions for mixed-order kinetics are derived for OSL curves. A peak shape parameter for linear modulation OSL is developed and special mixed-order expressions are derived for use in the computerized OSL curve deconvolution analysis.
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French, Andrew S., and Lisa L. Stockbridge. "Fractal and Markov behavior in ion channel kinetics." Canadian Journal of Physiology and Pharmacology 66, no. 7 (July 1, 1988): 967–70. http://dx.doi.org/10.1139/y88-159.
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Kinetic analysis of ion channel recordings attempts to distinguish the number and lifetimes of channel molecular states. Most kinetic analysis assumes that the lifetime of each state is independent of previous channel history, so that open and closed durations are Markov processes whose probability densities are sums of exponential decays. An alternative approach assumes that channel molecules have many configurtions with widely varying lifetimes. Rates of opening and closing then vary with the time scale of observation, leading to fractal kinetics. We have examined kinetic behavior in two types of channels from human and avian fibroblasts, using a maximum likehood method to test the dependence of rates on observational time scale. For both channels, openings showed mixed fractal and Markov behavior, while closings gave mainly fractal kinetics.
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Kutlugil’dina, Galiya G. "Kinetic scheme of apple pectin oxidative transformations under the action of the ozone-oxygen mixture." Butlerov Communications 61, no. 2 (February 29, 2020): 79–89. http://dx.doi.org/10.37952/roi-jbc-01/20-61-2-79.
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Mathematical modeling of apple pectin oxidative transformations (AP) under the action of the ozone-oxygen mixture in aqueous solutions (the reaction system "AP + O3 + O2 + H2O") has been carried out. The kinetic scheme of the oxidation process was compiled basing on the well-known ideas of liquid-phase oxidation mechanisms of organic compounds (taking into account the currently known experimental results on AP oxidation). Using the "KhimKinOptima" software package for the proposed scheme, the inverse and direct chemical kinetics problems were solved. The well-known literature data on the rate constants of elementary stages were used. The rate constants of the oxidation key stages have been determined after solving the chemical kinetics inverse problem with the index method of the observed and calculated kinetic data global optimization. It turned out that the rate constants of the individual stages obtained by calculation are in good agreement with the values of the rate constants taken from literary sources. The chemical kinetics direct problem has been solved with the found rate constants and allowed obtaining kinetic curves of all participants in the apple pectin ozonized oxidation. It was found that the kinetic curve of the accumulation of carboxyl groups, obtained experimentally, completely coincided with the theoretical dependence. It has been also shown that the proposed apple pectin oxidative conversion scheme in the "AP + O3 + O2 + H2O" reaction system allows one to explain all the currently available experimental results. The apple pectin ozonized oxidation under another initiator (Н2О2 + FeSO4) has been studied to confirm the kinetic scheme. To do this, 3 new stages has been introduced into the scheme proposed, characterizing the catalytic decomposition of hydrogen peroxide under a transition metal (Fe2+). By solving the chemical kinetics direct problem, the accumulation kinetic curves of the final reaction products were obtained. It has been found that the carboxyl groups accumulation kinetics in the reaction system "AP + O3 + O2 + H2O2 + FeSO4 + H2O" after the supplementary experiment coincided with the theoretical kinetic curve. Thereby, the accuracy of the apple pectin proposed oxidative conversion scheme is confirmed.
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Du, Hong Shuang, Xiang Yu Li, Xue Yong Ren, and Yan Xue Han. "Pyrolysis Kinetics Equation of Larch Bark." Advanced Materials Research 772 (September 2013): 313–18. http://dx.doi.org/10.4028/www.scientific.net/amr.772.313.
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The larch bark was examined by non-isothermal means to determine the mass loss kinetics of the thermal decomposition with linear temperature programming in nitrogen atmosphere. In this work, mechanism equation of = was used forCoats-Redfern integral methodat the different heating rates. The apparent activation energy, pre-exponential factor and the pyrolysis kinetic equations at the different heating rates were obtained. The pyrolysis temperature area was divided into two separate temperature regions for the pyrolysis kinetic equation and the two components were decomposed respectively at the two separate temperature regions. The global mass loss rate of the bark is considered as controlled respectively by the reactions of the two components respectively during the lower and higher temperature ranges. The kinetics of the two components are found to abide by the mechanism equation of =, which gave the best fits to the experimental data. The obtained kinetic equations of the bark at the different heating rates were additionally validated by the reasonable agreement between the experimental and calculated results.
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Arkhangelsky, I. V., I. A. Godunov, N. V. Yashin, Yu K. Naganovskii, and O. N. Shornikova. "The kinetics of intumescent flame retardant foaming." Pozharovzryvobezopasnost/Fire and Explosion Safety 29, no. 5 (December 2, 2020): 71–81. http://dx.doi.org/10.22227/pvb.2020.29.05.71-81.
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Introduction. Intumescent flame retardants are intensively used as passive fire protection means. Under fire conditions, these coatings foam and turn into coke, which turns into ash. These products have various fire resistant properties. These transformations are possible due to the foaming process, whose kinetics determines the fire protective characteristics of the compositions used. The paper considers the kinetics of the foaming process in the course of the pyrolysis of four different foaming compositions. The classical triad was used as a thermally expanding agent for the three of them, it includes ammonium polyphosphate, pentaerythritol, and melamine, and the fourth one has intercalated graphite.Research methods. Thermal analysis is widely used to identify and study various materials, substances and fire retardants. However, we have not found any kinetic studies performed using methods of thermal analysis in the literature. In this work, methods of non-isothermal kinetics are used to identify the mechanism of foaming. For this purpose, four series of thermogravimetric tests were carried out at different heating rates for each composition under study. The results of the experiment made it possible to solve inverse and direct kinetic problems and identify mechanisms of the processes.Results and discussion. Methods of non-isothermal kinetics were employed to show that low-temperature stages of thermolysis can be considered as gross-one-stage processes for all samples. The solution of the direct kinetic problem has helped to identify that the limiting foaming stage is described by the Avrami – Erofeev equation for all compositions under study, while the values of kinetic parameters differ significantly. Consequently, foaming proceeds are similar for samples having different compositions. The foaming of the sample containing intercalated graphite depends on heating conditions.Conclusions. It was identified that the studied compositions transform into the viscous-fluid state at high temperatures. In this case, the limiting stage of the foaming process is the nucleation of primary bubbles in the volume of the liquid phase. This process determines the kinetics of foaming, coke properties and its thermophysical characteristics.
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Khalil, Abdelouahed, and Tamàs Fülöp. "A comparison of the kinetics of low-density lipoprotein oxidation induced by copper or by γ-rays: Influence of radiation dose-rate and copper concentration." Canadian Journal of Physiology and Pharmacology 79, no. 2 (February 1, 2001): 114–21. http://dx.doi.org/10.1139/y00-080.
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The oxidation of low-density lipoproteins is the first step in the complex process leading to atherosclerosis. The aim of our study was to compare the kinetics of low density lipoprotein oxidation induced by copper ions or by oxygen free radicals generated by60Co γ-rays. The effects of copper concentration and irradiation dose-rate on LDL peroxidation kinetics were also studied. The oxidation of LDL was followed by the measurement of conjugated diene, hydroperoxides, and thiobarbituric acid reactive substance formation as well as α-tocopherol disappearance. In the case of gamma irradiation, the lag-phase before the onset of lipid peroxidation was inversely correlated to the radiation dose-rate. The radiation chemical rates (v) increased with increasing dose-rate. Copper-induced LDL peroxidation followed two kinetic patterns: a slow kinetic for copper concentrations between 520 µM, and a fast kinetic for a copper concentration of 40 µM. The concentration-dependent oxidation kinetics suggest the existence of a saturable copper binding site on apo-B. When compared with γ-rays, copper ions act as drastic and powerful oxidants only at higher concentrations ([Formula: see text]40 µM).Key words: LDL, peroxidation, kinetics, copper, γ-radiolysis, dose-rate.
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PONOMAREV, VASILY I. "SUBORDINATION OF DYNAMICAL EVOLUTION." Fluctuation and Noise Letters 09, no. 03 (September 2010): 271–75. http://dx.doi.org/10.1142/s0219477510000198.
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Anomalous kinetics, which does not fit the standard kinetic theory, has been found in many systems ranging from small neuronal networks to galactic clusters. Subordination of a "normal" dynamics, whose kinetics allows for a Brownian description, to the time flow generated by one-sided Lévy noise may result in "anomalous" evolution. We illustrate this straightforward and powerful method to produce an anomalous kinetics from a normal one by using a model of quantum kicked rotator.
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Jägle, Eric A., and Eric J. Mittemeijer. "Simulation of the Kinetics of Grain-Boundary Nucleated Phase Transformations." Solid State Phenomena 172-174 (June 2011): 1128–33. http://dx.doi.org/10.4028/www.scientific.net/ssp.172-174.1128.
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The kinetics of phase transformations for which nucleation occurs on parent-micro-structure grain boundaries, and the resulting microstructures, were investigated by means ofgeometric simulations. The influences of parent microstructure grain-boundary area density,parent grain-size distribution and parent→product kinetics were analysed. Additionally, thesimulated kinetics were compared with predictions from two kinetic models, namely a modelproposed for spatially random nucleation and a model proposed for grain-boundary nucleation.It was found that the simulated transformed fraction as function of time lies in between the twomodel predictions for all investigated parent microstructures and parent→product kinetics.
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Markham, J., T. J. McCarthy, M. J. Welch, and D. P. Schuster. "In vivo measurements of pulmonary angiotensin-converting enzyme kinetics. I. Theory and error analysis." Journal of Applied Physiology 78, no. 3 (March 1, 1995): 1158–68. http://dx.doi.org/10.1152/jappl.1995.78.3.1158.
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We developed a procedure for measuring pulmonary angiotensin-converting enzyme kinetics with fluorine-18 fluorocaptopril and positron emission tomography (PET). The method is based on the application of a compartmental receptor model that represents the kinetics of two species of ligand, presumably the trans and cis conformers of captopril. The input function was characterized and includes corrections for the labeled metabolites of fluorocaptopril. Application of the procedure to lung time-activity data obtained with PET produced estimates of kinetic parameters demonstrating fast kinetics for one conformer and slower kinetics for the other. Simulation studies were performed to evaluate the sensitivity of the estimated parameters to errors in the model assumptions and in measured values for variables required for analysis of the PET data. Estimates for two of the kinetic parameters, the amount of perfused unbound functional enzyme normalized to regional lung volume and the association rate constant for the trans conformer, were relatively stable even with large errors in the input data, varying < 30% from true values for all perturbations. Thus, the procedure produces reliable estimates of the kinetics of the trans conformer of captopril as well as theoretical curves that are close to the observed data.
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Tiwari, Aishwarya. "Calculations of the Average Number of Radicals per Particle in Emulsion Polymerization." International Journal for Research in Applied Science and Engineering Technology 9, no. VI (June 15, 2021): 1056–59. http://dx.doi.org/10.22214/ijraset.2021.35189.
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In emulsion polymerization, the free radicals enter the particles intermittently from the aqueous phase. The number of radicals per particleis given by the Smith-Ewart recursion relation which balances the rate of radical entry into, the rate of radical exit from and the rate of radical termination inside the particle. Models for emulsion polymerisation are based on the 0-1 kinetics or the pseudo-bulk kinetics. Small particles, low initiator concentrations and large number of particles favour the 0–1 kinetics, whereas the large particles, high initiator concentrations and small number of particles will favour pseudo-bulk kinetics. A given polymerization system may exhibit both these kinetic behaviours, initially following the 0-1 kinetics and during the later stages of polymerization following the pseudo-bulk kinetics. The aim of this work is to calculate the time dependent values of the average number of radicals per particle in emulsion polymerization for the pseudo-bulk kinetics.