Effect of O\u3csub\u3e2\u3c/sub\u3e Concentration in Ambient Mixture and Multiphase Radiation on Pollutant Formation in ECN Spray-A

The present study investigates the formation and evolution of soot and NOX in a high-pressure constant-volume combustion chamber. This work focuses on the effect of multiphase thermal radiation and O2 dilution in ambient/exhaust gases, some- times also referred to as exhaust gas recirculation(EGR), qualitatively and quantitatively. The spray-A case (n-dodecane as fuel) from Engine Combustion Network (ECN) is used as the target condition. Two different soot modeling approaches have been considered: a semi-empirical two-equation model and a detailed method of moments with interpolative closure (MOMIC) model. A multiphase photon Monte Carlo (PMC) solver with line-by-line (LBL) spectral data is used to resolve radiative heat transfer. Results show that effect of radiation on soot is minimal in spray-A. Inclusion of radiation modeling, on the other hand, marginally reduce NO prediction. Both peak soot and NO formation increases with O2 content in the ambient gas. Oxygen content in ambient gas is also found to have significant effect on soot sizes as the mean soot diameter increases along with considerable widening of the diameter distribution with the increase of O2 percentage in the ambient gas

Butea monosperma bark extract mediated green synthesis of silver nanoparticles: Characterization and biomedical applications

AbstractThe work deals with an environmentally benign process for the synthesis of silver nanoparticle using Butea monosperma bark extract which is used both as a reducing as well as capping agent at room temperature. The reaction mixture turned brownish yellow after about 24h and an intense surface plasmon resonance (SPR) band at around 424nm clearly indicates the formation of silver nanoparticles. Fourier transform-Infrared (FT-IR) spectroscopy showed that the nanoparticles were capped with compounds present in the plant extract. Formation of crystalline fcc silver nanoparticles is analysed by XRD data and the SAED pattern obtained also confirms the crystalline behaviour of the Ag nanoparticles. The size and morphology of these nanoparticles were studied using High Resolution Transmission Electron Microscopy (HRTEM) which showed that the nanoparticles had an average dimension of ∼35nm. A larger DLS data of ∼98nm shows the presence of the stabilizer on the nanoparticles surface. The bio-synthesized silver nanoparticles revealed potent antibacterial activity against human bacteria of both Gram types. In addition these biologically synthesized nanoparticles also proved to exhibit excellent cytotoxic effect on human myeloid leukemia cell line, KG-1A with IC50 value of 11.47μg/mL

An Investigation of Soot Evolution in High-pressure Spray Combustion

Morphological changes in soot emitted from combustion devices have a tremendous impact on the evolution of soot in the atmosphere. The current study focuses on understanding the physio-chemical phenomena leading to various morphological changes in soot from combustion devices. The primary objective of this study is to look at qualitative trends in soot particle statistics during high-pressure spray combustion of n-dodecane under engine-relevant conditions (Spray A). The simulations were performed with detailed chemistry in an unsteady Reynolds-averaged framework. A fully-coupled method of moments-based soot model and Monte Carlo radiation solver with line-by-line spectral data are also used to capture soot and radiation in the simulations. Simulations were validated using the experimental data provided by engine combustion network (ECN). Three different exhaust gas recirculation (EGR) configurations are investigated and it was found that the amount of soot, as well as mean soot diameter, increases with O2% in EGR. The diameter distribution was found to widen with increasing O2%. It was also found that the probability distribution of soot diameter evolves to a narrow unimodal shape from its initial bimodal shape as the time progresses

Property Rights and Policies for Sustainable Management of Marine Fisheries: The Indian Scenario

India enjoy a vast and versatile resource base in respect of her fisheries. However, the country presently has reached a crossroad so far as sustainable tapping of this resource base is concerned. By defining sustainability not merely as economic viability but also in terms of ecological and social compatibility, this paper looks into the problems and prospects of sustainable management of Indian Marine fisheries. It analyses the various types of negative externalities arising out of a lack of clearly defined ‘property rights’ regime, both from within and outside of this sector. A future policy perspective is developed through a critical examination of the Code of Conduct for Responsible Fisheries and the famous Supreme Court Judgement of December 1996 on coastal aquaculture, and then comparing the Common Fisheries Policy in respect of their capabilities in striking the necessary balance between economic needs and socio-ecological requirements. The paper highlights the need for evolving a network of ‘brotherhood’ type organisations institutionalized at local stakeholder’s level.

Molecular Arrangement and Fringe Identification and Analysis from Molecular Dynamics (MAFIA-MD): A Tool for Analyzing the Molecular Structures Formed during Reactive Molecular Dynamics Simulation of Hydrocarbons

Reactive molecular dynamics (RMD) simulations are becoming popular, with the recent developments in high-performance and efficient computing architecture, for investigating fundamental physico-chemical behaviors of reacting species. Due to the complexity of hydrocarbon systems, characterization of molecules formed during RMD simulations of hydrocarbons can be very challenging for simulations involving a large number of molecules. The novel post-processing utility “MAFIA-MD” – an acronym for “Molecular Arrangement and Fringe Identification and Analysis from Molecular Dynamics” – presented in this manuscript can analyze and perform molecular characterization of a large number of RMD trajectory files (.XYZ files) simultaneously. The utility will be useful for analysis and chemical characterization of trajectories without the large bond information files. A graphical user interface (GUI) is developed for easy operation. The utility analyzes the existing cyclic structures in the domain and generates statistics of alicyclic and aromatic hydrocarbons based on the number of carbon atoms. Alongside the statistical analysis, the program also separates the constituent molecules and extracts their chemical information in terms of Simplified Molecular-Input Line-Entry System (SMILES) and Spatial Data File (.SDF)”. A methodology for calculating fringe spacing is also implemented in the code for validation of RMD simulation with High-Resolution Transmission Electron Microscopy (HRTEM) images. Program summary Program title: MAFIA-MD CPC Library link to program files: https://doi.org/10.17632/s7dsk553fh.1 Developer\u27s repository link: https://github.com/kmmukut/MAFIA-MD.git Licensing provisions: MIT Programming language: Python 3.7 Supplementary material: Bash script for splitting long continuous trajectory files with multiple timestep into trajectory files for individual timestep and some example input trajectory files for testing. Nature of problem: Reactive molecular dynamics (RMD) simulations of hydrocarbons allow chemical reactions between different hydrocarbon molecules through bond breaking and new bond formation. The information about the chemical changes is stored in the bond information files and trajectory of individual atoms are stored in trajectory files. While the bond files can become very large for large simulations, trajectory files remain quite small. MAFIA-MD will be useful for practitioners interested in analyzing the chemical structures of emerging molecular clusters from small individual trajectory files without requiring the large, memory-intensive bond information files. Identification of chemical characteristics, particularly aromatic and alicyclic ring structures and molecular fringes, are important for gaining insights from RMD simulations of hydrocarbons, especially in exploration of soot formation during combustion. The capability of isolating the cyclic and non-cyclic molecules from trajectory files is the novel part of MAFIA-MD. Solution method: The coordinates of individual atoms are taken as the input for the program. The coordinates are then analyzed to create an adjacency matrix [1] based on the bond distance between carbon atoms. This adjacency matrix is then converted into a directed graph and the cyclic structures are extracted from the graph by implementing an efficient depth-first-search algorithm [2] developed by Johnson [3]. Apart from the ability to isolate cyclic and non-cyclic components by chemical structural analysis, a methodology to calculate fringe spacing is also implemented by calculating the distances between cyclic structures. The utility uses a Python interface for easy management of the input and output parameters. The detailed solution methodology has been discussed in the manuscript. Additional comments including restrictions and unusual features: In the current version, the utility can analyze only carbon and hydrogen atoms. The future versions will implement the addition of other common atoms found in aromatic molecules, e.g. nitrogen, oxygen, sulfur, etc. MAFIA-MD can be run on Linux, macOS, and Windows operating systems

The Coalescence of Incipient Soot Clusters

Reactive molecular dynamics (MD) simulations are employed to investigate the coalescence of incipient soot clusters. Initially, one thousand acetylene molecules collide and react with each other, allowing bond breakage and new bond formation upon collision, leading to various species (e.g., linear hydrocarbons, branched polyaromatic hydrocarbons) up to the formation of nascent soot clusters with diameter of up to 3.5 nm. The structure and composition of the formed soot clusters are quantified by the packing density and carbon-to-hydrogen (C/H) ratio, respectively, during nucleation and up to the formation of large nascent soot nanoparticles. Then, the nucleated incipient soot clusters are isolated from the surrounding reactive species and are allowed to coalesce with each other isothermally to investigate soot coalescence. The coalescence between incipient soot clusters of different sizes is elucidated at various process temperatures, ranging from 800 to 1800 K. The characteristic coalescence time of nascent soot is quantified by tracking the evolution of the particle surface area, for the first time. Soot clusters consisting of up to 760 atoms coalesce instantly (within 0.1 ns), especially at relatively low temperatures (i.e., 800–1000 K). At higher temperatures (1200–1600 K), incipient soot clusters are less prone to coalescence due to the larger fraction of constituent aromatic rings leading to more rigid particles. Large clusters consisting of more than 1300 atoms do not coalesce within the time scales investigated here (i.e., up to 5 ns). The employed reactive MD approach gives significant insight into fundamental soot formation and growth mechanisms, which are typically treated semi-empirically, facilitating a better understanding and more efficient control of soot in combustion processes

Unusual presentation of Klinefelter syndrome

Introduction: Klinefelter syndrome usually presents in the puberty and adulthood with its characteristic features. We report a boy who had Klinefelter syndrome with hypospadias and hydrocele. Case Note: Six and half year old boy had complaints of genitourinary problem in the form of hypospadias, small phallus and hydrocele. Karyotyping showed 47,XXY. Conclusion: This case illustrates that Klinefelter syndrome was presented in the infancy with hypospadias and hydrocele which are very uncommon presentation of the diseas

An unusual case of episodic quadriparesis

The natural history of untreated asymptomatic primary hyperparathyroidism (PHPT) remains incompletely understood. Increased level of parathyroid hormone produces the characteristic biochemical phenotype of hypercalcemia, hypophosphatemia and the various clinical sequelae of chronic hypercalcemia. Periodic paralysis (PP) is a group of disorders of different etiologies with episodic, short-lived and hyporeflexic skeletal muscle weakness, with or without myotonia, but without sensory deficit and without loss of consciousness. However, PHPT has rare association with episodic quadriparesis mimicking as PP

A case of normotensive pheochromocytoma with management dilemma

Introduction: We report an unusual case of normotensive pheochromocytoma detected incidentally, presenting a pre-operative management problem. Case Note: A 40-year-old lady with vague abdominal symptoms was initially discovered with a left adrenal incidentaloma by ultrasound abdomen, which was also revealed in computed tomography (CT). After exclusion of all the causes with possible necessary investigations, pheochromocytoma was confirmed with elevated 24 hour urinary metanephrine and normetanephrine. Her blood pressure was in low to normotensive range all throughout. She was attempted to be prepared with combined alpha and beta blockade but could not tolerate this regimen due to symptomatic hypotension. Subsequently, surgical preparation was planned cautiously with alpha-adenergic blockade only. With intensive monitoring, she underwent uneventful left adrenalectomy, and surgical pathology was consistent with pheochromocytoma. Conclusion: This case illustrates an unusual presentation of normotensive pheochromocytoma as adrenal incidentaloma. Pre-operative preparation in these patients can be achieved with alpha-adrenergic blockade, adequate hydration, and liberal salt intake