Severity of light pollution and its multifaceted impact: A mini review on the dark side of light

There is a surging concern regarding the adverse effects of light pollution on human well-being. This manuscript aims to emphasise the deleterious effects of uncontrolled night-light exposure on the health and mood of individuals residing in a highly populated elite metropolitan society compared to those residing in remote villagesin a scattered manner. A comprehensive study has been undertaken on the influence of unnecessary and excessive illumination of light during late-night hours on individuals' day-to-day lives. Prolonged exposure to unwanted intense artificial lighting disrupts the secretion of melatonin, interferes with the circadian rhythm, and unusual sleep patterns. Such disturbances can lead to significant health issues, including insomnia, depression, cardiovascular diseases, as well as an increased risk of breast and prostate cancer. Findings emphasize the need for a more holistic understanding of how artificial light, in intensity and periodicity, affects the physical and mental health of humans and the ecological system in entirety, specifically in urban settings

Deformation mechanics of quartz at a single asperity under hydrothermal conditions

Thesis (S.M. in Geophysics)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 92-97).Pressure solution is a naturally occurring deformation process in fluid-bearing rocks, with implications for sediment consolidation rates and deformation in the mid to upper crust. The process involves dissolution at asperities under load; diffusion along grain-to-grain contacts; and precipitation in the pore space. The kinetics of the process and the identity of the rate-limiting step in quartzose rocks are still a subject of debate and depend critically upon the structure of the inter-granular boundary during deformation. To investigate the mechanisms and kinetics of pressure solution and the effects of changes in boundary morphology, we continuously monitored deformation and the evolution of boundary morphology at a Y-cut convex quartz lens that was pressed against a flat surface of Y-cut quartz under hydrothermal conditions (425 0C, 150 MPa fluid pressure, 80-435 MPa effective normal stress) in a see-through optical pressure vessel. The pore fluid was de-ionized water, which became saturated with quartz during the initial heat-up period. Several different boundary morphologies were used, including polished flats, etched and roughened flats, and an island-channel structure fabricated by plasma etching. The island-channel structure had square pillars of quartz, either 4 micro meter or 8 micro meter on a side, surrounded by an inter-connected grid of open channels of comparable width. Deformation at the interface between the quartz flat and lens (i.e., inter-granular convergence) was observed in only one case: the 4pum island-channel structure. In that instance, pillars within the contact region were eroded at a rate that decreased with time, and SEM photomicrographs after the experiment showed significant cataclasis within and adjacent to the pillars. The total transient convergence (0.15i0.02pum) observed during the 472 hour period was less than the original pillar height (0.55±0.005pim). For all surface morphologies, the shapes of the surface structures in both the loaded and unloaded regions evolved, perhaps owing to capillarity forces. Although an inter-connected island-channel structure was initially imposed upon some of the experiments, this open, fluid-filled boundary structure was seen to be a transient phenomenon that was largely destroyed during convergence. Thus, there was no evidence for a dynamically stable interface, as previously suggested.by Sudhish Kumar Bakku.S.M.in Geophysic

Estimation of fracture compliance from tubewaves generated at a fracture intersecting a borehole

Understanding fracture compliance is important for characterizing fracture networks and for inferring fluid flow in the subsurface. In an attempt to estimate fracture compliance in the field, we developed a new model to understand tubewave generation at a fracture intersecting a borehole. Solving the dispersion relation in the fracture, amplitude ratios of generated tubewave to incident P-wave were studied over all frequency ranges. Based on the observations from the model, we propose that measuring amplitude ratios near a transition frequency can help constrain fracture compliance and aperture. The transition frequency corresponds to the regime where the viscous skin depth in the fracture is comparable to its aperture. However, measurements in the high frequency limit can place a lower bound on fracture compliance. Comparing the model to a previously published VSP dataset, we argue that compliance values of the order 10[superscript −10] −10[superscript −9] m/Pa may be possible in the field

Seismic imaging of hydraullically-stimulated fractures: A numerical study of the effect of the source mechanism

We present a numerical study of seismic imaging of hydraulically stimulated fractures using a single source from an adjacent fracturing-process. The source is either a point force generated from the perforation of the casing of the well or a double-couple as is typically observed from the induced microseismicity. We assume that the fracture is sufficiently stimulated to be imaged by reflected seismic energy. We show for a specific monitoring geometry of hydrofracturing that not only different waves (P and S) but also different source mechanisms from the same region form an image of different parts of the target fracture and thus add complementary information. The strategy presented here might be used as an additional monitoring tool of the hydrofracturing process.Massachusetts Institute of Technology. Earth Resources Laborator

Severe Esophagitis and Chemical Pneumonitis as a Consequence of Dilute Benzalkonium Chloride Ingestion: A Case Report

Background: Benzalkonium chloride (BAC) has been used as an active ingredient in a wide variety of compounds such as surface disinfectants, floor cleaners, pharmaceutical products and sanitizers. Solutions containing <10% concentration of BACs typically do not cause serious injury. As the available data regarding acute BAC toxicity is limited, we report a case of dilute benzalkonium chloride ingestion resulting in bilateral chemical pneumonitis and significant gastrointestinal injury requiring mechanical ventilatory support. The Case: A 42-year-old male presented with chief complaints of nausea, vomiting and excessive amount of blood- mixed oral secretions after accidental ingestion of approximately 100ml of BAC solution (<10%). Later he developed respiratory distress with falling oxygen saturation for which he was intubated and mechanical ventilatory support was administered. Computed tomography (CT) chest was suggestive of bilateral chemical pneumonitis and upper gastrointestinal (GI) endoscopy revealed diffuse esophageal ulcerations. The patient was managed with intravenous fluids, corticosteroids, proton pump inhibitor, empiric antibiotics and total parenteral nutrition. Conclusion: The present case report emphasizes that dilute BAC compounds can cause severe respiratory and gastrointestinal injuries. Immediate and aggressive medical treatment is crucial for improving patient outcomes and reducing the complication rates

Fracture characterization from seismic measurements in a borehole

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2015.Cataloged from PDF version of thesis.Includes bibliographical references (pages 219-227).Fracture characterization is important for optimal recovery of hydrocarbons. In this thesis, we develop techniques to characterize natural and hydraulic fractures using seismic measurements in a borehole. We first develop methods to characterize a fracture intersecting an open borehole by studying tubewave generation and attenuation at the fracture. By numerically studying the dispersion relation for fluid pressure in the fracture, we show that the tubewave measurements made in the transition regime from low to high frequency can constrain fracture compliance, aperture and length, while measurements made in the high-frequency regime can place a lower bound on fracture compliance. Analysis of field data suggest a large compliance value (10- 0m/Pa) for a meter-scale fracture and supports scaling of fracture compliance and applicability of scattering based methods for fracture characterization on a reservoir scale. We next study Distributed Acoustic Sensing (DAS), a novel Fiber Optic (FO) cable based seismic acquisition technology. We relate DAS measurements to traditional geophone measurements and make a comprehensive study of factors that influence DAS measurements. Using a layered borehole model, we analytically compare the sensitivity of DAS measurements to P- and S-wave incidence at arbitrary angles for the cases when the FO cable is installed in the borehole fluid or when cemented outside the casing. In addition, we study the azimuthal placement of the cable, the effect of cable design, and the effect of environmental conditions on time-lapse measurements. We show that DAS is a reliable tool for time-lapse monitoring. Finally, we analyze time-lapse DAS Vertical Seismic Profiling (VSP) data collected during a multi-stage hydraulic fracture treatment of a well drilled into a tight gas sandstone reservoir. We develop a processing workflow to mitigate the unique challenges posed by DAS data and propose methods for DAS depth calibration. We observe systematic and long-lived (over 10 days) time-lapse changes in the amplitudes of direct P-waves and nearly no phase changes due to stimulation. We argue that the time-lapse changes cannot be explained by measurement factors alone and that they may be correlated to the stimulated volume. Though the current geometry is not ideal, DAS is promising for hydraulic fracture monitoring.by Sudhish Kumar Bakku.Ph. D

Fracture compliance estimation using borehole tube waves

We tested two models, one for tube-wave generation and the other for tube-wave attenuation at a fracture intersecting a borehole that can be used to estimate fracture compliance, fracture aperture, and lateral extent. In the tube-wave generation model, we consider tube-wave excitation in the borehole when a P-wave is incident on the fracture. The amplitude ratio of the pressure due to the tube wave to that of the incident P-wave is a function of fracture compliance, aperture, and length. Similarly, the attenuation of a tube wave in the borehole as it crosses a fracture intersecting the borehole is also a function of fracture properties. Numerically solving the dispersion relation in the fracture, we study tube-wave generation and the attenuation coefficient as a function of frequency. We observed that measuring amplitude ratios or attenuation near a transition frequency can help constrain the fracture properties. The transition frequency corresponds to the regime in which the viscous skin depth in the fracture is comparable to its aperture. Measurements in the high-frequency limit can place a lower bound on fracture compliance and lateral extent. We evaluated the applicability of the tube-wave generation model to a previously published VSP data set and found that compliance values of the order 10[superscript −10]–10[superscript −9]  m/Pa are likely in the field. These observations support scaling of fracture compliance with fracture size.Eni-MIT Energy Initiative Founding Member Program (Eni Multiscale Reservoir Science Project

Copper modified iron oxide as heterogeneous photo-Fenton reagent for the degradation of coomasie brilliant blue R-250

943-948The heterogeneous photo-Fenton degradation of coomasie brilliant blue R–250 under visible light has been investigated using copper modified iron oxide, which has been prepared by coprecipitation method and characterized by IR spectroscopy, scanning electron microscopy and X-ray diffraction. The rate of photocatalytic degradation of dye follows pseudo-first order kinetics. The effects of various parameters like pH, concentration of dye, amount of photocatalyst, amount of H2O2 and light intensity on the rate of the photo-Fenton degradation has also been studied. Chemical oxygen demand of the reaction mixture before and after exposure has been determined. A tentative mechanism for the photocatalytic degradation has been proposed, wherein involvement of •OH radicals has been confirmed by the drastic reduction in the reaction rate in the presence of •OH radical scavengers such as isopropanol and butylated hydroxy toluene. The retardation with butylated hydroxy toluene is much higher than with isopropanol. Under similar conditions, efficiencies of Fe2O3 and copper modified Fe2O3 have been compared for the photocatalytic degradation of coomasie brilliant blue R-250

Superparamagnetic behaviour of nano-particles of Ni-Cu ferrite

169-172The nano-particles of Ni0.8Cu0.2Fe2O4 with a log-normal size distribution of the median diameter of 9 nm and standard deviation of 0.60 have been synthesized by the chemical co-precipitation method followed by annealing at 500°C. The cubic spinel structure in single phase has been confirmed by X-ray diffraction. Reduction in saturation magnetization has been explained on the basis that the magnetic moments in the surface layers, outside the core are in a state of frozen disorder. The dc magnetization is measured which show that the nano-particle sample is super-paramagnetic above the blocking temperature of 250 K. Secondly, the departure of fc curve from the zfc curve is suggestive of temporal relaxation