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Статті в журналах з теми "Digestion Simulation methods"
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Witaszek, Kamil, Marcin Herkowiak, Agnieszka A. Pilarska, and Wojciech Czekała. "Methods of Handling the Cup Plant (Silphium perfoliatum L.) for Energy Production." Energies 15, no. 5 (March 4, 2022): 1897. http://dx.doi.org/10.3390/en15051897.
Повний текст джерелаАнотація:
The aim of the study was to determine the possibilities of using cup plants (Silphium perfoliatum L.) to generate energy. The energy balances of the combustion and anaerobic digestion were compared. The research showed that cup plants could be used as a raw material for solid fuel and for anaerobic digestion. An energy balance simulation showed that electricity could be generated through the anaerobic digestion of cup plants. The following amounts could be generated in the anaerobic digestion process: 1069 kWhe from 1 Mg of the raw material fragmented with an impact mill, 738.8 kWhe from 1 Mg of the raw material extruded at a temperature of 150 °C, and as much as 850.1 kWhe from 1 Mg of the raw material extruded at 175 °C. The energy balance of the combustion of biofuel in the form of cup plant pellets showed that 858.28 kWht could be generated from 1 Mg of the raw material. The combustion of solid biofuel generated a relatively low amount of heat in comparison with the expected amount of heat from a biogas-powered cogeneration system due to the high energy consumption of the processes of drying and agglomeration of the raw material for the production of pellets.
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Sirovec, Sara, Ana Jurinjak Tušek, Maja Benković, Davor Valinger, Tea Sokač Cvetnić, Jasenka Gajdoš Kljusurić, and Tamara Jurina. "Emulsification of Rosemary and Oregano Aqueous Extracts and Their In Vitro Bioavailability." Plants 11, no. 23 (December 4, 2022): 3372. http://dx.doi.org/10.3390/plants11233372.
Повний текст джерелаАнотація:
Due to their richness in phenolic compounds, Mediterranean plants such as rosemary and oregano are increasingly recommended for consumption for their numerous health benefits. The pH shift and the presence of digestive enzymes significantly reduce the bioavailability of these biochemicals as they pass through the gastrointestinal tract. To prevent this degradation of phenolic compounds, methods such as emulsification of plant aqueous extracts are used. The aim of this study was to investigate the effects of emulsification conditions on the chemical properties (total polyphenolic content and antioxidant activity) of emulsified rosemary and oregano extracts. Response surface methodology was applied to optimize sunflower oil concentration, rotational speed, and emulsifier concentration (commercial pea protein). The emulsions prepared under optimal conditions were then used in bioavailability studies (in vitro digestion). The antioxidant activity of the emulsified rosemary/oregano extracts, measured by the DPPH method, remained largely stable when simulating in vitro digestion. Analysis of antioxidant activity after in vitro simulation of the gastrointestinal system revealed a higher degree of maintenance (up to 76%) for emulsified plant extracts compared to aqueous plant extracts. This article contributes to our understanding of how plant extracts are prepared to preserve their biological activity and their application in the food industry.
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Liu, Hui, Qian Li, and Chunbao Li. "Changes in the Structure and Digestibility of Myoglobin Treated With Sodium Chloride." Current Developments in Nutrition 5, Supplement_2 (June 2021): 661. http://dx.doi.org/10.1093/cdn/nzab045_043.
Повний текст джерелаАнотація:
Abstract Objectives Changes in the structure of myoglobin affect its digestibility and myoglobin can't be completely broken down of pepsin. The exact mechanism of this breakdown is not clear. It can be inferred that myoglobin is broken down into polypeptides whose structures do not fully conform to the spatial characteristics of digestive enzymes. Myoglobin dissolution in different salt concentrations and changes in secondary structure were examined by spectroscopic examination. The molecular dynamics simulation was used to study the stability of these structural changes and their combination with digestive enzymes. Finally, since the products of digestion are determined by the catalytic centers of digestive enzymes, the substrate channel is extended to study the relationship between digestive enzymes and substrates. Methods In this study, different concentrations of sodium chloride were added for a certain period of time in advance to detect changes in the secondary structure of myoglobin, leading to changes in digestibility. Myoglobin and digestive enzymes were docked for molecular dynamics simulations to analyze the energy and structural changes in the interactions between substrates and proteins. Results Salt-treated protein can affect the secondary structure changes of protein. High concentration of salt-treated protein will lead to protein aggregation and denaturation, affecting digestibility. Low concentration of salt-treated protein may lead to exposure of sleeping areas, reducing digestibility. In terms of structure, salt ions lead to changes in the bonding of amino acids in the protein and affect the substrate's entry into the enzyme activity center. Conclusions Treatment of myoglobin with different salt concentrations did not change its tertiary structure but low salt concentrations lowered its digestibility, probably due to salt ions altering a number of key amino acid bonds, making the structure more stable and less susceptible to digest. Some low molecular weight peptides remain after pepsin digestion. This may be due to the distance between the key amino acids in the active catalytic center of pepsin being insufficient to form stable conformations with small peptides. Funding Sources This work was supported by the grants from NSFC (32072211).
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Condrachi, Larisa, Ramón Vilanova, Montse Meneses, and Marian Barbu. "Anaerobic Digestion Process Control Using a Data-Driven Internal Model Control Method." Energies 14, no. 20 (October 16, 2021): 6746. http://dx.doi.org/10.3390/en14206746.
Повний текст джерелаАнотація:
Anaerobic digestion processes offer the possibility for wastewater treatment while obtaining a benefit through the obtained biogas. This paper aims to continue the effort to adopt data-driven control methods in the case of anaerobic digestion processes. The paper proposes a data-based Internal Model Control approach applied to an anaerobic digestion process. The paper deals extensively with the issue of choosing the reference model and proposing an engineering approach to this issue. The paper also addresses the issue of verifying robust stability, a very important aspect considering the uncertainties that characterize bioprocesses in general. The approach proposed in the paper is validated through a numerical simulation using the Anaerobic Digestion Model No. 1. During the validation of the proposed control solution, the main operating conditions were analyzed, such as the setpoint tracking performance, the rejection of disturbance generated by variations in the influent concentration, and the effect of the measurement noise on the controlled variable.
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Kitessa, S., G. G. Irish, and P. C. Flinn. "Comparison of methods used to predict the in vivo digestibility of feeds in ruminants." Australian Journal of Agricultural Research 50, no. 5 (1999): 825. http://dx.doi.org/10.1071/ar98169.
Повний текст джерелаАнотація:
Digestibility is a very useful index of the energy content of ruminant feeds, but cheaper and quicker laboratory methods are required as an alternative to the ultimate measure of in vivo digestibility using animals. These methods involve either prediction of digestibility from chemical composition or in vitro and in situ simulation of the digestion process. This review presents a range of chemical and in vitro techniques for predicting digestibility, together with an assessment of their advantages and limitations, particularly the degree to which they account for the sources of variation in in vivo digestibility in ruminants. In situ digestion of feed samples in the actual rumen environment is probably the most accurate of the non in vivo procedures, but is not suitable for routine application. Thein vitro gas production technique offers no advantages in prediction of total tract digestibility, but is useful for screening cereal grains for rate of starch hydrolysis in the rumen. The preferred procedure for routine laboratory prediction of digestibility is the pepsin-cellulase technique, provided amylase is included or high temperature digestion is used for samples high in starch content. Prediction of digestibility from chemical composition is not recommended. The optical technique of near infrared reflectance spectroscopy can be calibrated against any of the methods outlined in this review, and is unsurpassed in terms of speed and repeatability. Direct NIR prediction of in vivo digestibility is also possible, but is limited by the lack of adequate numbers of feed samples with known in vivo values. Future work should be aimed at filling this gap and also improving the accuracy of laboratory methods for predicting the digestibility of low quality feeds.
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Sainz, Roberto D., R. Lee Baldwin, and Ricardo F. Venazza. "Modelos de crecimiento, digestión y lactancia en bovinos." Corpoica Ciencia y Tecnología Agropecuaria 3, no. 2 (July 31, 2001): 65. http://dx.doi.org/10.21930/rcta.vol3_num2_art:188.
Повний текст джерелаАнотація:
<p>Los métodos utilizados comunmente para predecir el comportamiento animal como función del manejo de la alimentación, se encuentran en un proceso de cambio. Los sistemas actualmente utilizados para estimar los requerimientos animales, basados en ecuaciones algebráicas estáticas han empezado a ser sustituidos por modelos dinámicos de simulación capaces de caracterizar la respuesta animal para un rango de condiciones mucho mayor a aquel usado en los sistemas tradicionales. En este artículo se exponen los modelos para describir los procesos de crecimiento, digestión y lactancia bovinos. </p><p><strong><br /></strong></p><p><strong>Models for growth digestion and lactation in bovine</strong></p><p>The methods commonly used to predict animal behavior as a function of feeding management, are in a process of change. The systems currently used for estimating the animal requirements based on static algebraic equations have begun to be replaced by dynamic simulation models capable of characterizing animal response for a much wider range of conditions to that used in traditional systems. In this article models are presented to describe the processes of growth, digestion and feeding cattle.</p>
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Tormási, Judit, and László Abrankó. "Assessment of Fatty Acid-Specific Lipolysis by In Vitro Digestion and GC-FID." Nutrients 13, no. 11 (October 29, 2021): 3889. http://dx.doi.org/10.3390/nu13113889.
Повний текст джерелаАнотація:
The nutritional relevance of food compositional data could be improved by taking the bioaccessibility of these constituents into account. A lack of routine methods to assess the bioaccessibility of fatty acids (FAs) in food is one of the limiting factors of doing so. An analytical protocol is proposed for routine assessment of the extent of lipolysis via in vitro digestion simulation methods in food products. The established method provides specific information on each FA individually. Steps of the protocol including the Bligh and Dyer chloroform/methanol/water extraction of esterified and free FAs from in vitro digesta, methyl ester derivatization, and GC-FID analysis were specifically tailored to help routine work and were harmonized with the Infogest in vitro digestion simulation protocol (both v1.0 and v2.0). The method was applied to assess the degree of FA-specific lipolysis in a baked fish (carp) meal and the results showed that the FA composition of the original food significantly differed from that of the distribution of FFAs in the digesta. The use of gastric lipase (in Infogest v2.0 protocol) increased total FA release by 9.5% and its specific impact on palmitic acid was the most prominent.
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İnan, Yiğit, Selin Akyüz, Inci Kurt-Celep, Engin Celep, and Erdem Yesilada. "Influence of In Vitro Human Digestion Simulation on the Phenolics Contents and Biological Activities of the Aqueous Extracts from Turkish Cistus Species." Molecules 26, no. 17 (September 1, 2021): 5322. http://dx.doi.org/10.3390/molecules26175322.
Повний текст джерелаАнотація:
Oxidative stress is one of the significant precursors of various metabolic diseases such as diabetes, Parkinson’s disease, cardiovascular diseases, cancer, etc. Various scientific reports have indicated that secondary plant metabolites play an important role in preventing oxidative stress and its harmful effects. In this respect, this study was planned to investigate the phenolic profile and antioxidant and antidiabetic potentials of the aqueous extracts from Turkish Cistus species by employing in vitro methods. In vitro digestion simulation procedure was applied to all extracts to estimate the bioavailability of their phenolic contents. Total phenolic, flavonoid, phenolic acid and proanthocyanidin contents were determined for all phases of digestion. In addition, changes in the quantity of the assigned marker flavonoids (tiliroside, hyperoside and quercitrin) were monitored by High-Performance Thin Layer Chromatography (HPTLC) analysis. The antioxidant activity potentials of the extracts were studied by various methods to reveal their detailed activity profiles. On the other hand, in vitro α-amylase and α-glucosidase enzymes and advanced-glycation end product (AGE) inhibitory activities of the extracts were determined to evaluate the antidiabetic potentials of extracts. The results showed that aqueous extracts obtained from the aerial parts of Turkish Cistus species have rich phenolic contents and potential antioxidant and antidiabetic activities; however, their bioactivity profiles and marker flavonoid concentrations might significantly be affected by human digestion. The results exhibited that total phenolic contents, antioxidant activities and diabetes-related enzyme inhibitions of the bioavailable samples were lower than non-digested samples in all extracts.
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González-Arias, C. A., S. Marín, V. Sanchis, and A. J. Ramos. "Mycotoxin bioaccessibility/absorption assessment using in vitro digestion models: a review." World Mycotoxin Journal 6, no. 2 (May 1, 2013): 167–84. http://dx.doi.org/10.3920/wmj2012.1521.
Повний текст джерелаАнотація:
In the evaluation of the oral bioavailability of a mycotoxin, the first step is the determination of its bioaccessibility, i.e. the percentage of mycotoxin released from the food matrix during digestion in the gastrointestinal (GI) tract that could be absorbed through the intestinal epithelium. Different in vitro digestion models have been recently used for determination of bioaccessibility, thereby avoiding the use of more complex cell culture techniques or the use of animals in expensive in vivo experiments. In vitro methods offer an appealing alternative to human and animal studies. They usually are rapid, simple and reasonably low in cost, and can be used to perform simplified experiments under uniform and well-controlled conditions, providing insights not achievable in whole animal studies. The available in vitro methods for GI simulation differ in the design of the system, the composition of the physiological juices assayed, as well as in the use or not of intestinal microbiota. There are models that only simulate the upper part of the GI tract (mouth-stomach-small intestine), whereas other methods include the large intestine, so that the model chosen could have some influence on the bioaccessibility data obtained. Bioaccessibility depends on the food matrix, as well as on the contamination level and the way the food/feed is contaminated (spiked or naturally). This review focuses on the currently available data regarding in vitro digestion models for the study of the bioaccessibility or absorption of mycotoxins, detailing the characteristics of each digestion step and the importance of the physiological juices employed during digestion. The effect that different factors play on mycotoxin release from the food matrix in the GI tract is also considered, and existing data on bioaccessibility of the main mycotoxins are given.
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Gaida, D., C. Wolf, C. Meyer, A. Stuhlsatz, J. Lippel, T. Bäck, M. Bongards, and S. McLoone. "State estimation for anaerobic digesters using the ADM1." Water Science and Technology 66, no. 5 (September 1, 2012): 1088–95. http://dx.doi.org/10.2166/wst.2012.286.
Повний текст джерелаАнотація:
The optimization of full-scale biogas plant operation is of great importance to make biomass a competitive source of renewable energy. The implementation of innovative control and optimization algorithms, such as Nonlinear Model Predictive Control, requires an online estimation of operating states of biogas plants. This state estimation allows for optimal control and operating decisions according to the actual state of a plant. In this paper such a state estimator is developed using a calibrated simulation model of a full-scale biogas plant, which is based on the Anaerobic Digestion Model No.1. The use of advanced pattern recognition methods shows that model states can be predicted from basic online measurements such as biogas production, CH4 and CO2 content in the biogas, pH value and substrate feed volume of known substrates. The machine learning methods used are trained and evaluated using synthetic data created with the biogas plant model simulating over a wide range of possible plant operating regions. Results show that the operating state vector of the modelled anaerobic digestion process can be predicted with an overall accuracy of about 90%. This facilitates the application of state-based optimization and control algorithms on full-scale biogas plants and therefore fosters the production of eco-friendly energy from biomass.
Частини книг з теми "Digestion Simulation methods"
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Gihan Nanayakkara, Asanga, Phillip Chao, Jonathan B. Koea, and Sanket Srinivasa. "Simulation in Complex Laparoscopic Digestive Surgery." In Current Concepts and Controversies in Laparoscopic Surgery [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.108224.
Повний текст джерелаАнотація:
The adoption of laparoscopic techniques for complex digestive surgical procedures, such as hepatectomy and pancreatectomy, has been slow in comparison to other areas of surgery. Laparoscopy presents the surgeon with several challenges including ergonomics, lack of haptic feedback, altered fields of vision, and teamwork meaning that there is a significant learning curve for complex laparoscopic digestive surgery, even for the surgeon experienced in open procedures. Simulation is a useful method to train surgeons in complex procedures and has been suggested as a potential mechanism to decrease the duration of the surgeon learning curve in laparoscopic surgery. This chapter will explore current concepts in simulation for complex laparoscopic digestive surgery. Readers will develop an understanding of the role of simulation in surgical procedural training and evidence-based techniques that may be implemented in their own institution.
Тези доповідей конференцій з теми "Digestion Simulation methods"
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I, Silva, M., and De Bortoli, A. L. "SIMULATION OF BIOGAS PRODUCTION FROM THE ANAEROBIC DIGESTION PROCESS." In XXXVIII Iberian-Latin American Congress on Computational Methods in Engineering. Florianopolis, Brazil: ABMEC Brazilian Association of Computational Methods in Engineering, 2017. http://dx.doi.org/10.20906/cps/cilamce2017-0362.
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Bakalis, Serafim, Monica R. Jaime-Fonseca, and Peter Fryer. "Simulation of phenomena occurring during digestion of foods." In PROCEEDINGS OF THE INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2010 (ICCMSE-2010). AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4906678.
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Walker, Andy. "Estimating Reliability of a System of Electric Generators Using Stochastic Integration of Renewable Energy Technologies (SIRET) in the Renewable Energy Optimization (REO) Method." In ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/es2011-54283.
Повний текст джерелаАнотація:
The Renewable Energy Optimization (REO) screening method identifies the optimal combination of renewable energy technologies for a site subject to constraints imposed by the organization or by the physical limits of the site. The REO method calculates the life-cycle cost of a combination of renewable energy generators and then uses a solver to iterate until it finds the size of each generator that minimizes life-cycle cost. In 2007, NREL developed a method called “Stochastic Integration of Renewable Energy Technologies” (SIRET) [1, 2, 3, 7] to account for the interactions between multiple generators serving a load. SIRET calculates the quantity of electricity bought from and sold to the utility within a time interval, which allows an accurate economic model when the retail rate and sell-back rate of electricity differ. These two energy quantities calculated by SIRET are used to calculate utility costs in the REO life-cycle cost calculation. When one or more emergency generators and/or the electric grid are included with renewables as generation resources in the analysis, the SIRET algorithm can also be used to estimate the reliability of the system, where reliability is defined as the fraction of time in which any combination of generation resources is sufficient to meet the load. The SIRET algorithm is capable of analyzing any number of generation resources, and currently includes photovoltaics (PV), wind, solar thermal electric, biomass gasification, anaerobic digestion, landfill gas, daylighting, and an arbitrary number of emergency generators as well as the electric grid. An example consisting of PV, wind, and an emergency generator is presented to illustrate the method. This method is based on very simple and heuristic methods, and thus should be regarded only as a relative indicator of reliability, rather than an accurate prediction, but agreement with hourly simulation is presented as one benchmark of the effectiveness of the method.
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LEE, T. T., and P. WU. "DYNAMIC SIMULATION OF AN ANAEROBIC DIGESTION PROCESS USING ORTHOGONAL COLLOCATION ON FINITE ELEMENTS METHOD." In Proceedings of the International Conference on Scientific and Engineering Computation (IC-SEC) 2002. PUBLISHED BY IMPERIAL COLLEGE PRESS AND DISTRIBUTED BY WORLD SCIENTIFIC PUBLISHING CO., 2002. http://dx.doi.org/10.1142/9781860949524_0007.
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Chiou, Richard Y., Michael G. Mauk, Dharma T. Varapula, Senyu Wang, Carlos Ruiz, and Tzu-Liang (Bill) Tseng. "Microfluidic Systems for Studying Chemical Reactions, Mixing, and Heat Transfer." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-72307.
Повний текст джерелаАнотація:
Microsystems comprising microfluidic networks and miniaturized actuators, transducers, and sensors provide a convenient, revealing, and low-cost means for studying chemical reactions, separation processes such as filtration and extraction, phase changes, mixing, heat and mass transfer, and fluid flow phenomena. For instance, palm-sized plastic cartridges or cassettes (‘chips’) with channels, chambers, manifolds and other components for flow control and fluid actuation can be instrumented with embedded thermocouples and pressure sensors, and operated with small Peltier coolers/heaters and programmable syringe pumps or microrotary pumps. With proper design, the on-chip microfluidic processes can also be imaged with CCD cameras (especially using fluorescent dyes and particles), and infrared thermal cameras for temperature profiling. Such image (including video) capture and processing affords much more data compared to point sensors such as thermocouples and pressure transducers, and can be directly compared with finite element modeling. These systems are effective vehicles for project-based learning in fluid mechanics, heat transfer, chemical reaction engineering, separation processes and other unit operations, process control, and various biotechnical operations such as enzymatic digestion, nucleic acid amplification, and sample fractionation. The chips are made as bonded laminates from patterned acrylic, polycarbonate, thin metal sheet, and many other material types. Students can quickly design (using CAD software such as SolidWorks™), simulate (using FEM programs such as Comsol) microfluidic platforms, that can be rapid prototyped with laser machining, 3D printing, CNC machining, soft lithography, engraving and printed circuit board fabrication methods with a turn-around time of 1 day. The chip is instrumented using LabView™ or an Arduino™ microcontroller for data acquisition and process control. These benchtop or desktop systems make only modest demands on the resources of educational institutions, due to their low cost and safety, and minimal waste generation and reagent consumption. Also, their multidisciplinary nature affords an excellent opportunity for students to integrate their knowledge of CAD, simulation, prototyping, instrumentation and microcontrollers, statistical data analysis, and image processing and analysis. Further, these experiments give students a high level of hands on interaction and visualization of important unit operation processes. We discuss in detail some representative systems for heat exchangers, mixers, chemical reactors, and crystal growth, and their use as educational, project-based modules in the undergraduate engineering curriculum.
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Sitnic, Victor. "Using in silico RFLP method for the study of MC1R gene alleles in the species Sus Scrofa." In Xth International Conference of Zoologists. Institute of Zoology, Republic of Moldova, 2021. http://dx.doi.org/10.53937/icz10.2021.61.
Повний текст джерелаАнотація:
Abstract. In the present study we aimed to use a bioinformatics algorithm that predict RFLP fragmentation of swine MC1R alleles simulating the sequence digestion with over 700 restriction enzymes. The results show several restriction enzymes that have the potential to be used for genotyping of Sus scrofa individuals and for differentiation between hybrids and pure line wild boars (WB)/domestic pigs (DP). Genotyping studies of wild boars and domestic pigs in Moldova populations would allow the determination of introgression/backcrossing degree and would contribute to the elaboration of adequate conservation measures
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Meyer, Donna M., Adam Tillinghast, Nevan C. Hanumara, and Ana Franco. "Polyethylene Wear Debris From Hip Simulator Fluid Captured and Separated Using Bio-Ferrography." In ASME/STLE 2004 International Joint Tribology Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/trib2004-64328.
Повний текст джерелаАнотація:
This paper describes an experimental method, Bio-Ferrography, to separate ultra high molecular weight polyethylene (UHMWPE) wear debris, generated in hip simulators, from bovine serum lubricating fluid. A total of 54 experiments were performed in which an enzyme digestion “cocktail” was developed and used to clean the bovine serum samples of extraneous sugars, proteins and lipids that interfere with the UHMWPE particle separation. Erbium chloride was used to marginally magnetize particles in the fluid prior to passing through the ferrographic device. The particles were captured and separated from the fluid by traversing the treated serum across a magnetic gap of a bio-ferrograph. Morphology of the captured and separated wear debris was compared with particles from samples of fluid filtered through a paper sieve arrangement with pores of 0.05 micrometers in diameter. The UHMWPE wear debris collected using the described experimental method, were found to be between 0.1 and 20 micrometers in diameter with spherical and pill-shaped particles. The filtered UHMWPE particles were also in the same size range as the debris separated using bio-ferrography, 0.1 to 20 micrometers. To show that the experimental method captured UHMWPE particles, the spectra of the chemical composition of UHMWPE from an acetabular cup insert of a hip implant and of UHMWPE particles separated using Bio-Ferrography were compared and found to be the same. To further demonstrate that polyethylene could be captured and separated through the experimental method, manufactured polyethylene microspheres in the diameter range of 3 to 45 micrometers, were captured and separated using the bio-ferrographic process.
Звіти організацій з теми "Digestion Simulation methods"
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Pullammanappallil, Pratap, Haim Kalman, and Jennifer Curtis. Investigation of particulate flow behavior in a continuous, high solids, leach-bed biogasification system. United States Department of Agriculture, January 2015. http://dx.doi.org/10.32747/2015.7600038.bard.
Повний текст джерелаАнотація:
Recent concerns regarding global warming and energy security have accelerated research and developmental efforts to produce biofuels from agricultural and forestry residues, and energy crops. Anaerobic digestion is a promising process for producing biogas-biofuel from biomass feedstocks. However, there is a need for new reactor designs and operating considerations to process fibrous biomass feedstocks. In this research project, the multiphase flow behavior of biomass particles was investigated. The objective was accomplished through both simulation and experimentation. The simulations included both particle-level and bulk flow simulations. Successful computational fluid dynamics (CFD) simulation of multiphase flow in the digester is dependent on the accuracy of constitutive models which describe (1) the particle phase stress due to particle interactions, (2) the particle phase dissipation due to inelastic interactions between particles and (3) the drag force between the fibres and the digester fluid. Discrete Element Method (DEM) simulations of Homogeneous Cooling Systems (HCS) were used to develop a particle phase dissipation rate model for non-spherical particle systems that was incorporated in a two-fluid CFDmultiphase flow model framework. Two types of frictionless, elongated particle models were compared in the HCS simulations: glued-sphere and true cylinder. A new model for drag for elongated fibres was developed which depends on Reynolds number, solids fraction, and fibre aspect ratio. Schulze shear test results could be used to calibrate particle-particle friction for DEM simulations. Several experimental measurements were taken for biomass particles like olive pulp, orange peels, wheat straw, semolina, and wheat grains. Using a compression tester, the breakage force, breakage energy, yield force, elastic stiffness and Young’s modulus were measured. Measurements were made in a shear tester to determine unconfined yield stress, major principal stress, effective angle of internal friction and internal friction angle. A liquid fludized bed system was used to determine critical velocity of fluidization for these materials. Transport measurements for pneumatic conveying were also assessed. Anaerobic digestion experiments were conducted using orange peel waste, olive pulp and wheat straw. Orange peel waste and olive pulp could be anaerobically digested to produce high methane yields. Wheat straw was not digestible. In a packed bed reactor, anaerobic digestion was not initiated above bulk densities of 100 kg/m³ for peel waste and 75 kg/m³ for olive pulp. Interestingly, after the digestion has been initiated and balanced methanogenesis established, the decomposing biomass could be packed to higher densities and successfully digested. These observations provided useful insights for high throughput reactor designs. Another outcome from this project was the development of low cost devices to measure methane content of biogas for off-line (US$37), field (US$50), and online (US$107) applications.
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Harpaz, Sheenan, Steven G. Hughes, and Pinhas Lindner. Optimization of Diet for Post Larvel/Juvenile Sea Bass and Hybrid Stripped Bass Based on Enzymatic Profiles of their Digestive Tracts. United States Department of Agriculture, December 1995. http://dx.doi.org/10.32747/1995.7604924.bard.
Повний текст джерелаАнотація:
The overall goal of this research work was to identify the main proteolytic activities which take place in the digestive tracts of young bass fish, and use the knowledge acquired in order to improve feed protein utilization in juvenile fish based on their digestive capacity. The results of the work clearly showed that the young fish possess the entire profile of proteolytic enzymes which is found in adult fish. Yet, in the young fish the level of activity is substantially lower per gram tissue (or gram protein) as compared with the activity found in the digestive tracts of the same fish at an older (larger) age. In addition it was found that the main proteolytic enzyme in these fish is chymotrypsin which accounts for almost 80% of the proteolytic activity. An effort aimed at enhancing this activity has lead to the interesting finding that alcohol substantially enhances the proteolytic activity of fish intestines. Fish intestinal homogenates were used in order to evaluate the suitability of various feeds for the fish. Potential feed proteins were subjected to the proteolytic activity of the fish enzymes in vitro, in a manner simulating the natural process. The proteolytic activity was monitored by the valuation of the products, i.e. amino acid released. This method has proven to be a powerful tool which enables us to predict with a very high degree of accuracy the potential of a feed to promote growth. Selection of feed based on the proteolytic capacity of the fish degestive tracts can now be implemented in feed formulation, as anticipated in the original research proposal.