A dam-breach erosion model: I. Formulation

This paper, Part I in a series of two, develops a mathematical model for earthern dam breach erosion. This model constitutes an extension of the Breach Erosion of Earthfill Dams (BEED) model developed by Singh and Scarlatos (1987). Two aspects are emphasized: the evolution of the dam breach, and the subsequent flood and sediment routing. Simulation of dam breach evolution is based on hydrologic, geometric and geotechnic considerations. Einstein-Brown and Bagnold equations are utilized to compute the rate of erosion in the breached section. A water routing scheme, based on a modified version of the Muskingum method to simulate flow exchange between channel and floodplains, is used to route the resulting breach hydrograph. A sediment routing scheme based on the Muskingum method, modified to simulate deposition in floodplains, and deposition and scouring in the channel, is utilized to route the breach sediment graph. In Part II, the model is tested against historical dam failures, and an analysis is made to determine its sensitivity to various parameters.     

CXC Chemokine Signaling in Progression of Epithelial Ovarian Cancer: Theranostic Perspectives

Patients with epithelial ovarian cancer (EOC) are often diagnosed at an advanced stage due to nonspecific symptoms and ineffective screening approaches. Although chemotherapy has been available and widely used for the treatment of advanced EOC, the overall prognosis remains dismal. As part of the intrinsic defense mechanisms against cancer development and progression, immune cells are recruited into the tumor microenvironment (TME), and this process is directed by the interactions between different chemokines and their receptors. In this review, the functional significance of CXC chemokine ligands/chemokine receptors (CXCL/CXCR) and their roles in modulating EOC progression are summarized. The status and prospects of CXCR/CXCL-based theranostic strategies in EOC management are also discussed.     

Abstract Interpretation as Automated Deduction

Automata theory, algorithmic deduction and abstract interpretation provide the foundation behind three approaches to implementing program verifiers. This article is a first step towards a mathematical translation between these approaches. By extending Büchi’s theorem, we show that reachability in a control flow graph can be encoded as satisfiability in an extension of the weak, monadic, second-order logic of one successor. Abstract interpreters are, in a precise sense, sound but incomplete solvers for such formulae. The three components of an abstract interpreter: the lattice, transformers and iteration algorithm, respectively represent a fragment of a first-order theory, deduction in that theory, and second-order constraint propagation. By inverting the Lindenbaum–Tarski construction, we show that lattices used in practice are subclassical first-order theories.     

A novel concept for improved thermal management of the planar SOFC

A new design for the solid oxide fuel cell (SOFC) planar stack is proposed to minimise the thermal gradients in the cell. This design involves including a secondary air channel with flow in the counter direction to the cathodic air channel. The effectiveness of the new design is tested by means of a tank in series reactor (TSR) model of the SOFC. It is found that the new design is capable of reducing the steady state temperature difference across the cell to less than 2 K over a range of voltages, while satisfying the requirements on fuel utilisation (FU) and cell average temperature. This is achieved by manipulating the primary air channel inlet flow rate and the secondary air channel inlet temperature. More modelling and experimental studies are required to further investigate the proposed design.     

Microfiltration of thin stillage: Process simulation and economic analyses

In plant scale operations, multistage membrane systems have been adopted for cost minimization. We considered design optimization and operation of a continuous microfiltration (MF) system for the corn dry grind process. The objectives were to develop a model to simulate a multistage MF system, optimize area requirements and stages required for a multistage system and perform economic analysis of a multistage MF system for a 40 million gal/yr ethanol plant. Total area requirement decreased with number of stages but there was tradeoff between higher capital costs involved at higher number of stages. To achieve thin stillage total solids concentration from 7 to 35%, a 5 stage membrane system was found to be optimum with area requirement of 655 m² for minimum cost. Increase in the input stream flow rate from 1.54 × 10⁶ to 2.89 × 10⁶ L/day significantly increased the total capital cost of the system by 47%. Compared to a single stage system, an optimal system had a 50% reduction in operating costs. Optimal system also showed potential to process more than twice the amount of thin stillage compared to a 4 effect evaporator system for given conditions.     

Performance analysis of a solar photovoltaic operated domestic refrigerator

This paper describes the fabrication, experimentation and simulation stages of converting a 165 l domestic electric refrigerator to a solar powered one. A conventional domestic refrigerator was chosen for this purpose and was redesigned by adding battery bank, inverter and transformer, and powered by solar photovoltaic (SPV) panels. Various performance tests were carried out to study the performance of the system. The coefficient of performance (COP) was observed to decrease with time from morning to afternoon and a maximum COP of 2.102 was observed at 7 AM. Simulations regarding economic feasibility of the system for the climatic conditions of Jaipur city (India) were also carried out using RETScreen 4. It was observed that the system can only be economically viable with carbon trading option taken into account, and an initial subsidy or a reduction in the component costs – mainly SPV panels and battery bank.     

Study on TL and OSL characteristics of indigenously developed CaF2:Mn phosphor

CaF₂:Mn phosphor is known for its high thermoluminescent sensitivity and dose linearity up to few kGy. In the present study CaF₂ phosphor with different concentration of Mn dopant was prepared and was characterized through different techniques. The phosphor was prepared through chemical root using CaCO₃, HF acid and MnCl₂ as raw materials following co-precipitation method. TL sensitivity of the prepared phosphor was compared with other well established phosphors used for radiation dosimetry. It was found that the TL sensitivity is higher by a factor of 10 with respect to LiF:Mg, Ti, TLD-100 and half to that of CaSO₄:Dy (0.05 mol%) phosphor. X-ray diffraction, TL emission spectrum and ESR spectrum taken of the prepared phosphor confirms the crystal structure, Mn²⁺ emission and incorporation Mn in the crystal, respectively. No significant fading of the dosimetric peak was observed of the prepared phosphor for a storage period of 45 days. The dose linearity of the phosphor was found to be in the range of 50 Gy-3 kGy within an uncertainty of about 10%. An attempt was made to determine the kinetic parameters of TL glow curve and the parameters related to optically stimulated luminescence. In view of its long range of dose linearity, it can be used for the dosimetry of commercial irradiator generally used for the irradiation of food and grains in our country.     

Light-colored compound conductive coatings based on CuI: Effect of volume fraction of CuI on morphology and electrical conductivity

A novel family of compound conductive coating has been designed and developed using Cu(I)I (cuprous iodide) as electrical conducting material. A carefully designed polyurethane matrix material allowed incorporation of large volume fraction of CuI, much above its critical volume concentration, while maintaining good film integrity. Electrical conductivity of a series of such coatings has been studied using dielectric spectroscopy, as a function of volume fraction of CuI and temperature. The light-colored (white–beige colored) coatings having electrical conductivity of the order of up to 10⁻³–10⁻² S cm⁻¹ have been demonstrated. Scanning electron microscopy (SEM) has been used to characterize bulk coating microstructures. The result of this study provides useful insight for fabrication of compound conductive coatings based on CuI.     

TrkB Receptor Signalling: Implications in Neurodegenerative,Psychiatric and Proliferative Disorders

The Trk family of receptors play a wide variety of roles in physiological and disease processes in both neuronal and non-neuronal tissues. Amongst these the TrkB receptor in particular has attracted major attention due to its critical role in signalling for brain derived neurotrophic factor (BDNF), neurotrophin-3 (NT3) and neurotrophin-4 (NT4). TrkB signalling is indispensable for the survival, development and synaptic plasticity of several subtypes of neurons in the nervous system. Substantial evidence has emerged over the last decade about the involvement of aberrant TrkB signalling and its compromise in various neuropsychiatric and degenerative conditions. Unusual changes in TrkB signalling pathway have also been observed and implicated in a range of cancers. Variations in TrkB pathway have been observed in obesity and hyperphagia related disorders as well. Both BDNF and TrkB have been shown to play critical roles in the survival of retinal ganglion cells in the retina. The ability to specifically modulate TrkB signalling can be critical in various pathological scenarios associated with this pathway. In this review, we discuss the mechanisms underlying TrkB signalling, disease implications and explore plausible ameliorative or preventive approaches.