Modeling of phenol degradation system using artificial neural networks

Pseudomonas pictorum (NICM-2077) an effective strain used in the biodegradation of phenol was grown on various nutrient compounds which protect the microbes while confronting shock loads of concentrated toxic pollutants during waste water treatment. In the present study the effect of glucose, yeast extract, (NH₄)₂SO₄ and NaCl on phenol degradation has been investigated and a Artificial Neural Network (ANN) Model has been developed to predict degradation. Also the learning, recall and generalization characteristics of neural networks has been studied using phenol degradation system data. The network model was then compared with a Multiple Regression Analysis model (MRA) arrived from the same training data. Further, these two models were used to predict the percentage degradation of phenol for a blind test data. Though both the models perform equally well ANN is found to be better than MRA due to its slightly higher coefficient of correlation, lower RMS error value and lower average absolute error value during prediction.     

Aerobic batch degradation of phenol using immobilized Pseudomonas putida

Alginate concentrations between 2 and 4% had little effect on the degradation rate of phenol by alginate-immobilized Pseudomonas putida. Ten-degree shifts from 25°C resulted in approximately 30% slower degradation. Maximal degradation rates were favored at pH 5.5–6.0. The response of degradation rate to increased air flow in the bubble column used was almost linear and an optimal higher than 16 vol vol⁻¹ was indicated, although free cells appeared in the reaction medium above 12 vol vol⁻¹. When the initial phenol concentration was raised, degradation rate was not significantly affected until levels higher than 1200 mg ml⁻¹ where performance was markedly reduced. Increasing the ratio of total bead volume to medium volume gave progressively smaller increases in degradation rate. At a medium volume to total bead volume ratio of 5:1, the maximum degradation rate was 250 mg L⁻¹ h⁻¹. Received 24 November 1998/ Accepted in revised form 27 January 1999     

Kinetics of phenol degradation using Pseudomonas putida MTCC 1194

Pseudomonas putida (MTCC 1194) has been used to degrade phenol in water in the concentration range 100–1000?ppm. The inhibition effects of phenol as substrate have become predominant above the concentration of 500?ppm (5.31?mmoles/dm³). The optimum temperature and initial pH required for maximum phenol biodegradation were 30?°C and 7.00 respectively. From the degradation data the activation energy (E _a ) was found to be equal to 13.8?kcal/g mole substrate reacted. The most suitable inoculum age and volume for highest phenol degradation were 12?hrs and 7% v/v respectively. Surfactants had negligible effect on phenol biodegradation process for this microorganism. Monod model has been used to interpret the free cell data on phenol biodegradation. The kinetic parameters have been estimated upto initial concentration of 5.31?mmoles/dm³. μ _max and K _S gradually increased with higher concentration of phenol. However, beyond the phenol concentration of 5.31?mmoles/dm³, the inhibition became prominant. The μ _max has been to be a strong function of initial phenol concentration. The simulated and the experimental phenol degradation profiles have good correspondence with each other.     

Anaerobic degradation of phenol using an acclimated mixed culture

Summary Anaerobic methanogenesis of phenol using mixed cultures derived from cow dung and municipal sewage sludge and adapted to phenol was done in batch reactors. The phenol degradation rate depended on the period in which the culture was acclimated to phenol. Interference in phenol uptake by glucose was observed. Consumption of both phenol and acetic acid was observed when an acetate-adapted culure was used. A phenol-acclimated culture was able to degrade dihydroxy phenols thus indicating the feasibility of cross-acclimation. Offprint requests to: P. Ghosh     

Mathematical modeling of the hypothalamic-pituitary-adrenal system activity

Mathematical modeling has proven to be valuable in understanding of the complex biological systems dynamics. In the present report we have developed an initial model of the hypothalamic-pituitary-adrenal system self-regulatory activity. A four-dimensional non-linear differential equation model of the hormone secretion was formulated and used to analyze plasma cortisol levels in humans. The aim of this work was to explore in greater detail the role of this system in normal, homeostatic, conditions, since it is the first and unavoidable step in further understanding of the role of this complex neuroendocrine system in pathophysiological conditions. Neither the underlying mechanisms nor the physiological significance of this system are fully understood yet.     

Continuous anaerobic phenol degradation using an adapted mixed culture

A mixed culture derived from cow dung and sewage sludge and adapted to phenol was used for anaerobic phenol degradation. The phenol degradation rate depended on the period of adaptation of the mixed culture to phenol. In the continuous process, a higher degradation rate (2500 mg.1^-1 d^-1) and better reactor stability was achieved with a granular activated-carbon-packed bed reactor than with a stirred tank reactor.The authors are with the Department of Biochemical Engineering & Biotechnology, Indian Institute of Technology, Delhi Hauz Khas, New Delhi, India.     

Mathematical modeling of the regulation of caspase-3 activation and degradation

Caspases are thought to be important players in the execution process of apoptosis. Inhibitors of apoptosis (IAPs) are able to block caspases and therefore apoptosis. The fact that a subgroup of the IAP family inhibits active caspases implies that not each caspase activation necessarily leads to apoptosis. In such a scenario, however, processed and enzymically active caspases should somehow be removed. Indeed, IAP-caspase complexes covalently bind ubiquitin, resulting in degradation by the 26S proteasome. Following release from mitochondria, IAP antagonists (e.g. second mitochondrial activator of caspases (Smac)) inactivate IAPs. Moreover, although pro-apoptotic factors such as irradiation or anti-cancer drugs may release Smac from mitochondria in tumor cells, high cytoplasmic survivin and ML-IAP levels might be able to neutralize it and, consequently, IAPs would further be able to bind activated caspases. Here, we propose a simple mathematical model, describing the molecular interactions between Smac deactivators, Smac, IAPs, and caspase-3, including the requirements for both induction and prevention of apoptosis, respectively. In addition, we predict a novel mechanism of caspase-3 degradation that might be particularly relevant in long-living cells.     

Vulnerability assessment and impact factor analysis of marine economic system based on fuzzy comprehensive evaluation model

It is crucial to examine the vulnerability of the marine economy and analyze the main influencing factors to promote the sustainable development of marine economy. In this rearch, a vulnerability assessment index system of marine economic system was constructed from four aspects: stress, sensitivity, elasticity and response ability. Combined with the coefficient of variation method, 40 assessment indexes in the index system were objectively selected and reduced. Based on the assessment set obtained from the fuzzy comprehensive evaluation model, the weighted average method and weighted linear sum method were used to measure the vulnerability level type and evolution characteristics of the marine economic system. The key influencing factors were analyzed using a principal component analysis. We found that the vulnerability of Jiangsu's marine economic system in 2007–2016 was moderate and low, and it was significantly improved during 2012–2015, especially in 2015, it was mild vulnerable and below. The GDP of coastal areas, fixed asset investment of the whole society, value added of marine and related industries, coastal wind power generation capacity, per capita consumption expenditure of urban residents and list all were the key factors affecting the vulnerability of the marine economy. We analyzed the characteristics and influencing factors of vulnerability change and put forward targeted suggestions.     

The degradation mechanism of phenol induced by ozone in wastes system

A distinct understanding for the degradation mechanism of phenol induced by ozone is very essential because the ozonation process, one of the advanced oxidation processes (AOPs), is attractive and popular in wastewater treatment. In the present work, the detailed reactions of ozone and phenol are investigated employing the density functional theory B3LYP method with the 6-311++G (d, p) basis set. The profiles of the potential energy surface are constructed and the possible reaction pathways are indicated. These detailed calculation results suggest two degradation reaction mechanisms. One is phenolic H atom abstraction mechanism, and the other is cyclo-addition and ring-opening mechanism. Considering the effect of solvent water, the calculated energy barriers and reaction enthalpies for the reaction of O3 and phenol in water phase are both lower than those in gas phase, though the degradation mechanisms are not changed. This reveals that these degradation reactions are more favorable in the water solvent. The main reaction products are C(6)H(5)OO· radical, a crucial precursor for forming PCDD/Fs and one ring-opening product, which are in good agreement with the experimental observations.     

BRAGI: A comprehensive protein modeling program system

A protein modeling program package has been developed. The user friendly system is implemented on high performance graphic devices and facilitates the modeling of a protein with an unknown three-dimensional structure out of that of a homologous one or the design of new variants. A wide range of features can be used by the researcher for this purpose. The system is written in FORTRAN 77 and E&S GSR functions or the HP implementation of the PHIGS standard, respectively.     

Mathematical modeling of the malignancy of cancer using graph evolution

We report a novel computational method based on graph evolution process to model the malignancy of brain cancer called glioma. In this work, we analyze the phases that a graph passes through during its evolution and demonstrate strong relation between the malignancy of cancer and the phase of its graph. From the photomicrographs of tissues, which are diagnosed as normal, low-grade cancerous and high-grade cancerous, we construct cell-graphs based on the locations of cells; we probabilistically generate an edge between every pair of cells depending on the Euclidean distance between them. For a cell-graph, we extract connectivity information including the properties of its connected components in order to analyze the phase of the cell-graph. Working with brain tissue samples surgically removed from 12 patients, we demonstrate that cell-graphs generated for different tissue types evolve differently and that they exhibit different phase properties, which distinguish a tissue type from another.     

Mathematical modeling of intracellular membrane transport: Receptor-mediated endocytosis and degradation of low-density lipoproteins

Receptor-mediated endocytosis of low-density lipoproteins, their transport within endosomes, and subsequent degradation in lysosomes are essential components of the molecular system for cholesterol homeostasis in vertebrate cells. The system under study is also an example of clathrin-mediated endocytosis, a possible way of cell communication with the environment. Construction of a detailed mathematical model of this system would allow comprehensive study of mechanisms and kinetics of molecular processes and evaluation of the effect of various mutations, disorders, and environmental changes on the system operation. Receptor-mediated endocytosis of low-density lipoprotein particles and their subsequent degradation in the cell have been modeled. A network of mono-and bimolecular reactions best describing the system has been proposed. The results of calculation of kinetic parameters of the molecular system obtained with the model are in agreement with experimental evidence.     

Mathematical modeling of intracellular membrane transport: Receptor-mediated endocytosis and degradation of low-density lipoproteins

Receptor-mediated endocytosis of low-density lipoproteins, their transport within endosomes, and subsequent degradation in lysosomes are essential components of the molecular system for cholesterol homeostasis in vertebrate cells. The system under study is also an example of clathrin-mediated endocytosis, a possible way of cell communication with the environment. Construction of a detailed mathematical model of this system would allow comprehensive study of mechanisms and kinetics of molecular processes and evaluation of the effect of various mutations, disorders, and environmental changes on the system operation. Receptor-mediated endocytosis of low-density lipoprotein particles and their subsequent degradation in the cell have been modeled. A network of mono-and bimolecular reactions best describing the system has been proposed. The results of calculation of kinetic parameters of the molecular system obtained with the model are in agreement with experimental evidence.

     

Mathematical modeling of cascading migration in a tri-trophic food-chain system

Diel vertical migration is a behavioral antipredator defense that is shaped by a trade-off between higher predation risk in surface waters and reduced growth in deeper waters. The strength of migration of zooplankton increases with a rise in the abundance of predators and their exudates (kairomone). Recent studies span multiple trophic levels, which lead to the concept of coupled vertical migration. The migrations that occur at one trophic level can affect the vertical migration of the next lower trophic level, and so on, throughout the food chain. This is called cascading migration. In this paper, we introduce cascading migration in a well-known model (Hastings and Powell, Ecology 73:896–903, 1991). We represent the dynamics of the system as proposed by Hastings and Powell as a phytoplankton–zooplankton–fish (prey–middle predator–top predator) model where fish affect the migrations of zooplankton, which in turn affect the migrations of motile phytoplankton. The system under cascading migration enhances system stability and population coexistence. It is also observed that for a higher rate of cascading migration, the system shows chaotic behavior. We conclude that the observations of Hastings and Powell remain true if the cascading migration rate is high enough.     

Mathematical model for evaluation of mass transfer limitations in phenol biodegradation by immobilized Pseudomonas putida

A mathematical model is proposed to analyze the mass transfer limitations in phenol biodegradation using Pseudomonas putida immobilized in calcium alginate. The model takes into account internal and external mass transfer limitations, substrate inhibition kinetics and the dependence of the effective diffusivity of phenol in alginate gel on cell concentration. The model is validated with the experimental data from batch fermentation. The effect of various operating conditions such as initial phenol concentration, initial cell loading, alginate gel loading on the biodegradation of phenol is experimentally demonstrated. Phenol degradation time is found to decrease initially and reach stationary value with increase in cell loading as well as gel loading. The model predicts these trends reasonably well and shows the presence of external mass transfer limitations. A new concept of effectiveness factor is introduced to analyze the overall performance of batch fermentation.     

Mathematical modeling of bioassays

The high affinity and specificity of biological receptors determine the demand for and the intensive development of analytical systems based on use of these receptors. Therefore, theoretical concepts of the mechanisms of these systems, quantitative parameters of their reactions, and relationships between their characteristics and ligand–receptor interactions have become extremely important. Many mathematical models describing different bioassay formats have been proposed. However, there is almost no information on the comparative characteristics of these models, their assumptions, and predic- tive insights. In this review we suggested a set of criteria to classify various bioassays and reviewed classical and contempo- rary publications on these bioassays with special emphasis on immunochemical analysis systems as the most common and in-demand techniques. The possibilities of analytical and numerical modeling are discussed, as well as estimations of the minimum concentrations that may be detected in bioassays and recommendations for the choice of assay conditions.     

Sustainable transportation systems performance evaluation using fuzzy logic

Sustainability has become an overarching concern for transportation policy and planning around the world. This article presents an approach for urban transport sustainability performance evaluation using fuzzy logic. This article presents a model for transport sustainability performance evaluation. Appropriate transport sustainability indicators were identified based on literature. The model addresses all major dimensions of transport sustainability such as Economic Sustainability, Social Sustainability, Environmental Sustainability and Transportation System Effectiveness. Transport sustainability index has been computed as (5.05, 6.62, 8.12) and weaker transport sustainability attributes were found. Transport sustainability index highlights the question how far toward becoming transport sustainable is an enterprise or region? While, weaker transport sustainability attributes reveals that how can an enterprise or region improve its transport sustainability effectively? Appropriate actions were initiated to improve urban transport sustainability performance. The results indicate that the model is capable of effectively assessing transport sustainability and has practical relevance. An example is also used to illustrate the approach developed. The results obtained using fuzzy approach has been validated with conventional crisp approach. 20 transport sustainability attributes out of 60 are found to be weaker and appropriate actions were derived to improve the weaker attributes.