Green Chemistry is a relatively new emerging field that strives to work at the molecular level to achieve sustainability. The field has received widespread interest in the past decade due to its ability to harness chemical innovation to meet environmental and economic goals simultaneously. Green Chemistry has a framework of a cohesive set of Twelve Principles, which have been systematically surveyed in this critical review. This article covers the concepts of design and the scientific philosophy of Green Chemistry with a set of illustrative examples. Future trends in Green Chemistry are discussed with the challenge of using the Principles as a cohesive design system (93 references).

Green Chemistry: Principles and Practice

Antibacterial activity of zinc oxide nanoparticles (ZnO-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many microorganisms exist in the range from hundreds of nanometers to tens of micrometers. ZnO-NPs exhibit attractive antibacterial properties due to increased specific surface area as the reduced particle size leading to enhanced particle surface reactivity. ZnO is a bio-safe material that possesses photo-oxidizing and photocatalysis impacts on chemical and biological species. This review covered ZnO-NPs antibacterial activity including testing methods, impact of UV illumination, ZnO particle properties (size, concentration, morphology, and defects), particle surface modification, and minimum inhibitory concentration. Particular emphasize was given to bactericidal and bacteriostatic mechanisms with focus on generation of reactive oxygen species (ROS) including hydrogen peroxide (H2O2), OH− (hydroxyl radicals), and O2 −2 (peroxide). ROS has been a major factor for several mechanisms including cell wall damage due to ZnO-localized interaction, enhanced membrane permeability, internalization of NPs due to loss of proton motive force and uptake of toxic dissolved zinc ions. These have led to mitochondria weakness, intracellular outflow, and release in gene expression of oxidative stress which caused eventual cell growth inhibition and cell death. In some cases, enhanced antibacterial activity can be attributed to surface defects on ZnO abrasive surface texture. One functional application of the ZnO antibacterial bioactivity was discussed in food packaging industry where ZnO-NPs are used as an antibacterial agent toward foodborne diseases. Proper incorporation of ZnO-NPs into packaging materials can cause interaction with foodborne pathogens, thereby releasing NPs onto food surface where they come in contact with bad bacteria and cause the bacterial death and/or inhibition.

/pdf/review-on-zinc-oxide-nanoparticles-antibacterial-activity-2smaigi8sc.pdf

Review on Zinc Oxide Nanoparticles: Antibacterial Activity and Toxicity Mechanism.

https://eva.fing.edu.uy/pluginfile.php/55828/mod_resource/content/1/kalogiru.pdf

Solar thermal collectors and applications

An introduction to heat transfer

Band bending in semiconductors: chemical and physical consequences at surfaces and interfaces.


 Scroll expanders are generally used for low temperature power generation applications due to their inherently small built-in volume ratio. The working fluid and operating conditions play an important role in the expander performance as well as its physical size and volume ratio. Hence, a comparative study of scroll expander performance was carried out between two different working fluids, R433C and supercritical (s-CO2). The s-CO2 Brayton cycle achieved a maximum cycle efficiency of 13.6% at an expander supply pressure of 11 MPa. Two separate scroll geometries were modeled for supercritical Organic Rankine Cycle (SORC) using R433C and s-CO2 Brayton cycle for the operating conditions that provided the maximum cycle performance. The s-CO2 scroll geometry achieved a maximum expander efficiency of 80% with a volume ratio of 2.5 and a diameter of 19 cm. The high inlet temperatures required a much higher volume ratio of 6.2 and scroll diameter of 30 cm for the R433C based SORC leading to greater leakages and lower expander efficiency of 62%. The comparative study shows that s-CO2 is better suited for scroll expander than R433C at such high expander supply temperatures.

A Comparative Study of Scroll Expander Performance Using CO2 and Zeotropic Mixtures As Working Fluids

A combined power/cooling cycle, which combines the Rankine and absorption refrigeration cycles, uses ammonia-water mixture as a working fluid and produces power and refrigeration while power is the primary goal. This cycle, also known as the Goswami Cycle, can be used as a bottoming cycle using waste heat from a conventional power cycle or as an independent cycle using low temperature sources such as geothermal and solar energy. This paper presents a parametric analysis of the combined cycle. Parametric study of the cycle was carried out in the commercial software Chemcad 6.1. The thermodynamic property data used in simulations were validated with experimental data. Chemcad model was also compared with simulations previously carried out in the process simulator Aspen Plus. The agreement between the two sets has proved the accuracy of the model developed in Chemcad. Then, optimum operating conditions were found for a range of ammonia concentration in the basic solution, isentropic expander efficiency and boiler pressure. It is shown that the cycle can be optimized for net work, cooling output, effective first and exergy efficiencies.Copyright © 2009 by ASME

Parametric Study of a Combined Power and Cooling Thermodynamic Cycle for Low Temperature Heat Sources

Waste-to-Energy Combustion

Ocean Energy Technology

In this article, we investigate the ternary LiNH2–MgH2–LiBH4 hydrogen storage system by adopting various processing reaction pathways. The stoichiometric ratio of LiNH2:MgH2:LiBH4 is kept constant with a 2:1:1 molar ratio. All samples are prepared using solid-state mechano-chemical synthesis with a constant rotational speed, but with varying milling duration. Furthermore, the order of addition of parent compounds as well as the crystallite size of MgH2 are varied before milling. All samples are intimate mixtures of Li–B–N–H quaternary hydride phase with MgH2, as evidenced by XRD and FTIR measurements. It is found that the samples with MgH2 crystallite sizes of approximately 10 nm exhibit lower initial hydrogen release at a temperature of 150

D. Yogi Goswami

Papers

A Comparative Study of Scroll Expander Performance Using CO2 and Zeotropic Mixtures As Working Fluids

Parametric Study of a Combined Power and Cooling Thermodynamic Cycle for Low Temperature Heat Sources

Waste-to-Energy Combustion

Ocean Energy Technology

Processing Analysis of the Ternary LiNH2-MgH2-LiBH4 System for Hydrogen Storage