Studies on the Skin Safety of Parabens

are the most common preservatives in skin care products. Alone or in combination with other compounds they are used as a preservative to protect microbial growth in skin care products. Parabens have been successfully used by the cosmetics and pharmaceutical industries for more than 60 years. Parabens are alkyl esters of p-hydroxybenzoic acid. There are seven types of parabens available in the market. However, mostly four types of parabens are commonly used in cosmetics products; these are methyl paraben (MP), ethyl paraben (EP), propyl paraben (PP), and butyl paraben (BP). Those are esterified with an alkyl chain which is structurally reliable for anti-microbial activities. Paraben safety studies proved that parabens are safe for the human body. Therefore, The United States Food and Drug Administration approved parabens as preservatives in skin care products and they set a concentration of 0.4% w/w in a single paraben and 0.8% w/w in a combination of parabens. However, recent studies on the effects of parabens reported that they exhibit estrogenic activity on human skin. Thus, The Danish government banned all paraben use in cosmetics. Although, European Union (EU) government regulatory boards claim that current concentrations of parabens in skin products are safe for cosmetic products. Consequently, there is conflicting evidence over the safety of parabens used as preservatives in skin care products. This research is presented in three chapters. The first chapter explains the feasibility of addressing the safety of parabens through cytotoxicity assay and establishes a ranking order of paraben safety according to their toxicity. This study was conducted with an SRB assay. In the second chapter, the % metabolism of parabens through pig skin has been studied. Pig skin was chosen because it has similar histological and physiological properties to human skin. The permeation of parabens through Franz diffusion cells was determined over 24 hours using HPLC analysis for the quantification of parabens and their metabolite. This permeability study described a comparative analysis of parabens metabolized through pig skin and established a ranking order of paraben permeation according to their rate of metabolism. In the third chapter, we investigated the metabolism of parabens in human keratinocyte cells. The recommended concentration of each paraben was incubated with human keratinocyte cells at three different times of incubation. After incubation, parabens and their metabolite were extracted by lysis buffer and quantified using HPLC analysis. During this study, the % metabolism ranking order of these parabens in human keratinocytes was also determined

Procedural Generation of Complex Roundabouts for Autonomous Vehicle Testing

High-definition roads are an essential component of realistic driving scenario simulation for autonomous vehicle testing. Roundabouts are one of the key road segments that have not been thoroughly investigated. Based on the geometric constraints of the nearby road structure, this work presents a novel method for procedurally building roundabouts. The suggested method can result in roundabout lanes that are not perfectly circular and resemble real-world roundabouts by allowing approaching roadways to be connected to a roundabout at any angle. One can easily incorporate the roundabout in their HD road generation process or use the standalone roundabouts in scenario-based testing of autonomous driving

Sediment Delivery to Sustain the Ganges-Brahmaputra Delta Under Climate Change and Anthropogenic Impacts

The principal nature-based solution for offsetting relative sea-level rise in the Ganges-Brahmaputra delta is the unabated delivery, dispersal, and deposition of the rivers’ ~1 billion-tonne annual sediment load. Recent hydrological transport modeling suggests that strengthening monsoon precipitation in the 21st century could increase this sediment delivery 34-60%; yet other studies demonstrate that sediment could decline 15-80% if planned dams and river diversions are fully implemented. We validate these modeled ranges by developing a comprehensive field-based sediment budget that quantifies the supply of Ganges-Brahmaputra river sediment under varying Holocene climate conditions. Our data reveal natural responses in sediment supply comparable to previously modeled results and suggest that increased sediment delivery may be capable of offsetting accelerated sea-level rise. This prospect for a naturally sustained Ganges-Brahmaputra delta presents possibilities beyond the dystopian future often posed for this system, but the implementation of currently proposed dams and diversions would preclude such opportunities

DataSheet1_Characterization and spatiotemporal variations of ambient seismic noise in eastern Bangladesh.docx

This study analyses the ambient noise field recorded by the seismic network, TREMBLE, in Bangladesh, operational since late 2016. Horizontal-vertical spectral ratios confirm the placement of stations on sediment, many situated on thick sedimentary columns, consistent with local geology. Noise across the broadband spectrum is systematically examined. A high amplitude local microseism (0.4–0.8 Hz) is recorded, originating near the coast and modulated by local tides. The secondary microseism (0.15–0.35 Hz) correlates strongly with wave height in the Bay of Bengal and varies with seasons, with greater power and higher horizontal amplitude in the monsoon season when the wave height is highest. The microseism increases in amplitude and decreases in frequency as a tropical depression moves inland. The primary microseism (∼0.07–0.08 Hz) exhibits no seasonal changes in power but display strong horizontal energy which changes with seasons. Low frequency (0.02–0.04 Hz) noise on the horizontal components has a 24-h periodicity, due to instrument tilt caused by atmospheric pressure changes. A station located next to the major Karnaphuli River shows elevated energy at ∼5 Hz correlated to periods of high rainfall. Anthropogenic noise (∼4–14 Hz) is station-dependent, demonstrating changing patterns in human activity, such as during Ramadan, national holidays and the COVID pandemic. Our work holds implications for seismic deployments, earthquake, and imaging studies, while providing insights into the interaction between the atmosphere, ocean, and solid Earth.</p