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.

Passive Solar Heating, Cooling, and Daylighting

In one embodiment, a chromatic device includes an active layer and an electrolyte layer in contact with the active layer, the electrolyte comprising an oxidant and a salt, wherein the active layer has a color that blocks light when metal is not in electrical contact with the active layer but changes to a translucent color that transmits light when metal is placed in electrical contact with the active layer, wherein the active layer changes color without applying electrical energy to the active layer.

/pdf/chromatic-devices-comprising-a-salt-based-electrolyte-oh2bvu44k6.pdf

Chromatic devices comprising a salt-based electrolyte


 Recent research has shown that it is possible to achieve significant cooling by radiative methods without the use of mechanical equipment that require significant amount of electrical power. These passive cooling methods rely on reflecting most of the solar radiation and emitting radiation in the “atmospheric window” wavelength ranges where the atmosphere is transparent, so that a surface exchanges radiation directly with the extremely cold outer space. This literature review noted that almost all published experimental studies on radiative cooling were conducted under different environmental conditions and methodologies, making it almost impossible to compare the results. In this paper, we present a literature review, focusing on daytime radiative cooling performance, that showed an array of testing methods and environmental conditions, leading to the research question of how these technologies would compare with the same testing standard. Slight variations in environmental conditions, setup, and instrumentation from one experiment to another can present large differences in reported performance, even for the same passive radiative cooling device. Examples of setups include non-standard insulated testing chambers, convection barriers, vacuum chambers, shading devices, and instruments like feedback heaters, pyranometers, infrared radiometers and thermocouples. The testing methods reviewed point to the need for a standard cooling potential performance measurement method for the advancement of passive radiative cooling technology.

A Review of Passive Cooling Technology Performance Testing Methods

Speciation is known to control fundamental aspects of metal processing and electrochemical behavior such as solubility and redox potentials. Deep eutectic solvents (DESs) are an emerging class of green, low-cost and designer solvents and are being explored as alternatives for recycling nuclear fuel and critical materials. However, there is a lack of knowledge about the behavior of metals in them. Here, for the first time, we synthesized three new DESs based on alkyltriphenylphosphonium bromide (CnPPh3Br), with varied alkyl chain lengths (n), as the hydrogen-bond acceptor along with decanoic acid (DA) as the hydrogen-bond donor and explored the redox speciation of uranyl nitrate. The changes in the Fourier transform infrared and NMR spectra helped elucidate the formation of hydrogen bonds in DES. The absorption maxima of uranyl in DES was red-shifted by 10 nm compared to the free uranyl, with concomitant increase in intensity and luminescence lifetime, which suggested a strong interaction of uranyl nitrate with DES. Cyclic voltammetry was probed to understand the redox thermodynamics, transport properties, and heterogeneous electron transfer kinetics of the irreversible electron transfer of uranyl ions in the three DESs. Electrochemical and spectroscopic techniques together with density functional theory calculations unlocked microscopic insights into the solvation and speciation of UO22+ ions in three DESs and also the associated unusual trends observed in the physical properties of the DESs. The hydrogen-bonded structure of DES plays a crucial role in the redox behavior of the UO22+ ion due to its strong potent complexation with its components. The basic findings of the present work can have far-reaching consequences for the extraction, electrochemical separation, and future development of redox-based separation processes in the nuclear fuel cycle.

Mechanistic Approach to Reveal Interaction of Uranyl Ions in Alkyltriphenylphosphonium Bromide-Based Deep Eutectic Solvent.

Intracellular labile iron pool (LIP) has been associated with cellular toxicity, and regarded as one of the factors affecting many diseases. However, fluorescence probes for detection of LIP are limited. Herein, we present a novel, BODIPY based, triplet ground state pro-fluorescent dinitroxide, as a turn on sensor for similar purpose. The biradical probe has been synthesized, and was seen to be highly effective in detecting LIP, more importantly in a concentration-dependent manner, in a variety of cell lines. The probe showed high sensitivity with Fe(II)-selective turn-on response via reduction of the biradical. This is a first example of a BODIPY based fluorescence turn-on sensor selective towards Fe(II). 

D. Yogi Goswami

Papers

Passive Solar Heating, Cooling, and Daylighting

Chromatic devices comprising a salt-based electrolyte

A Review of Passive Cooling Technology Performance Testing Methods

Mechanistic Approach to Reveal Interaction of Uranyl Ions in Alkyltriphenylphosphonium Bromide-Based Deep Eutectic Solvent.

Stable, Triplet Ground State BODIPY-TEMPO Diradical as a Selective Turn on Fluorescence Sensor for Intracellular Labile Iron Pool