The results of carbon-doped zinc oxide nanoparticles synthesized by CO2 microwave plasma at atmospheric pressure are presented. The 2.45-GHz microwave plasma torch and feeder for injecting Zn granules are used in the synthesis of zinc oxide nanoparticles. The Zn granules (13.5&#x2009;g/min) were introduced into the microwave plasma by CO2 (5&#x2009;l/min) swirl gas. The microwave power delivered to the CO2 microwave plasma was 1&#x2009;kW. The synthesis of carbon-doped zinc oxide nanoparticles was carried out in accordance with CO2&#x2009;+&#x2009;Zn&#x2009;&#x2192;&#x2009;carbon-doped ZnO&#x2009;+&#x2009;CO. The synthesized carbon-doped zinc oxide nanoparticles have a high purity hexagonal phase. The absorption edge of carbon-doped zinc oxide nanoparticles exhibited a red shift from a high-energy wavelength to lower in the UV-visible spectrum, due to band gap narrowing. A UV-NIR spectrometer, X-ray diffraction, emission scanning electron-microscopy, energy dispersive X-ray microanalysis, Fourier transform infrared spectroscopy, and a UV-Vis-NIR spectrophotometer were used for the characterization of the as-produced products.

Se Min Chun

Dae Hyun Choi

Jong Bae Park

Yong Cheol Hong

Optical and Structural Properties of ZnO Nanoparticles Synthesized by CO2 Microwave Plasma at Atmospheric Pressure

Nanomaterials exhibit unique physical and chemical properties and, hence, they have received much attention from scientists and researchers in different areas of environmental sciences, specifically in bioremediation. Bioremediation provides a good clean-up strategy for some types of waste, but as it is expected, it will not be useful for all. For example, bioremediation may not provide a feasible strategy at sites with high concentrations of chemicals that are toxic to most microorganisms. These include heavy metals and salt. Further, the advancement in science and technology has increased standard of living which directly or indirectly contributes to the increase in waste and toxic material. Therefore, the remediation of contaminants by use of existing technology is not effective and efficient in cleaning up the environment. Hence, nanomaterials may be applied for bioremediation, which will not only have less toxic effect on microorganisms, but will also improve the microbial activity of the specific waste and toxic material which will reduce the overall time consumption as well as reduce the overall cost. In this paper we have briefly summarized the major types of nanomaterials that have been used so far in bioremediation of waste and toxic materials.

Md. Rizwan

Man Singh

Chanchal K. Mitra

Roshan K. Morve

Ecofriendly Application of Nanomaterials: Nanobioremediation

Iron nanoparticles are synthesized and size characterized using HRTEM, FESEM, and XRD. Polyethylene glycol(PEG), carboxymethyl cellulose (CMC), and poly N-vinyl pyrrolidone (PVP) are used as nanoparticle stabilizers. The sizes of Fe nps are found to be 9&#x2009;nm, 14&#x2009;nm, and 17&#x2009;nm&#x2009;&#xb1;&#x2009;1&#x2009;nm corresponding to PEG, CMC, and PVP stabilizers, respectively. The three different iron nanoparticles (Fe nps) prepared are used as catalysts in the hydrogenation reaction of various substituted aromatic ketones to alcohols with NaBH4. The progress of the reaction was monitored using time variance UV spectra. Kinetic plots are made from the absorbance values and the pseudo first order rate coefficient values are determined. Catalytic efficiency of the Fe nps is obtained by comparing the pseudo first order rate coefficient values, times of reaction, and &#x25; yield. Fe-PEG nps was found to act as better catalyst than Fe-CMC nps and Fe-PVP nps. Also, effects of substituents in the aromatic ring of ketones reveal that +I substituents are better catalysed than &#x2013;I substituents.

L. Parimala

J. Santhanalakshmi

Studies on the Iron Nanoparticles Catalyzed Reduction of  Substituted Aromatic Ketones to Alcohols

Biomediated methods are considered to be a safer alternative to conventional physicochemical methods for the fabrication of nanomaterials due to their eco-friendly nature. In the present study, silver nanoparticles (AgNPs) were synthesized by microwave irradiation using aqueous rhizome extract of the medicinal plant Alpinia galanga. The nanoparticles were also synthesized under ambient condition without the assistance of microwave radiation and the former method was found to be much faster than the latter. The silver nanoparticles were characterized by UV-vis., FTIR, XRD, and HR-TEM analysis. UV-vis. spectroscopic studies provided ample evidences for the formation of nanoparticles. The FTIR spectrum confirmed the presence of plant phytochemicals as stabilizing agent around the AgNPs. XRD and HR-TEM analyses clearly proved the crystalline nature of the nanoparticles. From the TEM images, the nanoparticles were found to be roughly spherical in shape with an average diameter of 20.82 &#xB1; 1.8&#x2009;nm. The nanoparticles showed outstanding catalytic activity for the reduction of methyl orange by NaBH4. The AgNPs were also evaluated for their antimicrobial activity by well diffusion method against S. aureus, B. subtilis, V. cholera, S. paratyphi, and A. niger. They were found to be highly toxic against all the tested pathogenic strains.

Siby Joseph

Beena Mathew

Microwave Assisted Biosynthesis of Silver Nanoparticles Using the Rhizome Extract of Alpinia galanga and Evaluation of Their Catalytic and Antimicrobial Activities

In modern days, refrigeration systems are important for industrial and domestic applications. The systems consume more electricity as compared to other appliances. The refrigeration systems have been investigated thoroughly in many ways to reduce the energy consumption. Hence, nanorefrigerant which is one kind of nanofluids has been introduced as a superior properties refrigerant that increased the heat transfer rate in the refrigeration system. Many types of materials could be used as the nanoparticles to be suspended into the conventional refrigerants. In this study, the effect of the suspended copper oxide (CuO) nanoparticles into the 1,1,1,2-tetrafluoroethane, R-134a is investigated by using mathematical modeling. The investigation includes the thermal conductivity, dynamic viscosity, and heat transfer rate of the nanorefrigerant in a tube of evaporator. The results show enhanced thermophysical properties of nanorefrigerant compared to the conventional refrigerant. These advanced thermophysical properties increased the heat transfer rate in the tube. The nanorefrigerant could be a potential working fluid to be used in the refrigeration system to increase the heat transfer characteristics and save the energy usage.

S. A. Fadhilah

R. S. Marhamah

A. H. M. Izzat

Copper Oxide Nanoparticles for Advanced Refrigerant Thermophysical Properties: Mathematical Modeling

We have calculated the nucleation region (NR) location of Si nanocrystal grains prepared by pulsed laser ablation (PLA) with fluence of 4&#x2009;J/cm2 in 10 Pa gas at room temperature, and ambient gases were He, Ne, and Ar, respectively. Results of calculation indicated that NR width in Ne gas was narrowest, while it was widest in He gas. Maximum mean size of grains deposited on substrates under ablated spot, which were placed horizontally, was the smallest in Ne gas. It would be attribute to more effective energy transfer during the process of collision when atomic mass of Si and ambient gas Ne are more close to each other. In this work, an additional gas flow with the same element as ambient gas was introduced, which is vertical to the plume axis at different lateral positions above ablated spot.

Zechao Deng

Lizhi Chu

Xuecheng Ding

Aili Qin

Guangsheng Fu

Yinglong Wang

Influence of Gas Sort on the Nucleation Region Width of Si Nanocrystal Grains Prepared by Pulsed Laser Ablation

Green chemistry has been an eye catching area of interest since the past few years. With the problem of energy crisis looming high and its constraint being particularly vulnerable on the developing economies, the need for giving alternative traditional chemistry a serious consideration as well as adequate room for development has received significant boost through the coveted efforts of multidisciplinary and interdisciplinary scientific fields. Nanoscience has been the right field in this dimension as it opens up the door to multiple opportunities through enabling a number of chemical, biochemical, and biophysical transformations in a significantly easier and reliable manner. The use of nanoparticles has made the fields of catalysis, synthesis, and enzyme immobilizations as well as molecular interactions a lot much easier, rapid and easily controllable. This review article sheds light on the popular alternative synthesis routes being employed for the synthesis of nanoparticles, the pivotal being from microbes, plants, and chemical routes via sonication, microwaving, and many others.

Parth Malik

Ravi Shankar

Vibhuti Malik

Nitin Sharma

Tapan Kumar Mukherjee

Green Chemistry Based Benign Routes for Nanoparticle Synthesis

This paper presents the performance of ductile cast iron grinding machining using water-based zinc oxide nanoparticles as a coolant. The experimental data was utilized to develop the mathematical model for first- and second-order models. The second order gives worthy performance of the grinding. The results indicate that the optimum parameters for the grinding model are 20&#x2009;m/min table speed and 42.43&#x2009;&#x3bc;m depth of cut for single-pass grinding. For multiple-pass grinding, optimization is at a table speed equal to 35.11&#x2009;m/min and a depth of cut equal to 29.78&#x2009;&#x3bc;m. The model fit was adequate and acceptable for sustainable grinding using a 0.15&#x25; volume concentration of zinc oxide nanocoolant. This paper quantifies the impact of water-based ZnO nanoparticle coolant on the achieved surface quality. It is concluded that the surface quality is the most influenced by the depth of cut(s) and table speed.

M. M. Rahman

K. Kadirgama

Performance of Water-Based Zinc Oxide Nanoparticle Coolant during Abrasive Grinding of Ductile Cast Iron

Silver and silver halides nanoparticles (NPs) (Ag, AgCl, AgBr, and AgI) capped with two different stabilizers (sodium citrate and nonionic surfactant Tween 80) were obtained via sodium borohydride reduction of silver nitrate in an aqueous solution. The effect of the biocidal action of as-prepared synthesized materials against yeast cells Saccharomyces cerevisiae was compared to the effect produced by silver nitrate and studied through the measurement of cell loss and kinetics of K+ efflux from the cells depending on concentration of silver. The results clearly indicate that the silver ions either remained in the dispersion of silver NPs and silver halides NPs after their synthesis or were generated afterwards by dissolving silver and silver halides particles playing a major part in the cytotoxic activity of NPs against yeast cells. It was also supposed that this activity most likely does not relate to the damage of cell membrane.

A. A. Kudrinskiy

A. Yu. Ivanov

E. V. Kulakovskaya

A. I. Klimov

P. M. Zherebin

D. V. Khodarev

Anh-Tuan Le

Le Thi Tam

G. V. Lisichkin

Yu. A. Krutyakov

The Mode of Action of Silver and Silver Halides Nanoparticles against Saccharomyces cerevisiae Cells

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Journal of Nanoparticles