scholarly journals Conductometric Gas Nanosensors

2009 ◽  
Vol 2009 ◽  
pp. 1-18 ◽  
Author(s):  
Girolamo Di Francia ◽  
Brigida Alfano ◽  
Vera La Ferrara
Keyword(s):  
Room Temperature ◽  
Chemical Reactivity ◽  
Metal Oxide Nanoparticles ◽  
Chemical Properties ◽  
Metal Nanowires ◽  
Fundamental Properties ◽  
Research Activities ◽  
Sensor Field ◽  
Physical And Chemical ◽  
And Chemical Properties

This paper presents a review of the current research activities in the field of gas nanosensors. Nanomaterials are characterized by physical and chemical properties that differ from their macroscopic counterparts and, in particular, by an enhanced chemical reactivity even at room temperature. This effect has stimulated the development of chemical sensors based on several different nanomaterials. Here we focus most attention on carbon nanotubes, silicon and metal oxide nanoparticles and metal nanowires. After introducing a few general definitions a discussion on the fundamental properties of the nanostate used in the sensor field is presented and several nanosensors, based on the aforementioned nanomaterials, are discussed. Finally, some personal conclusions will be drawn.

scholarly journals Topological invariants for the line graphs of some classes of graphs

2019 ◽  
Vol 17 (1) ◽  
pp. 1483-1490
Author(s):  
Xiaoqing Zhou ◽  
Mustafa Habib ◽  
Tariq Javeed Zia ◽  
Asim Naseem ◽  
Anila Hanif ◽  
...  
Keyword(s):  
Communication Theory ◽  
Chemical Reactivity ◽  
Line Graph ◽  
Chemical Properties ◽  
Topological Invariants ◽  
Line Graphs ◽  
Physical And Chemical Properties ◽  
Physical And Chemical ◽  
Ladder Graphs ◽  
And Chemical Properties

AbstractGraph theory plays important roles in the fields of electronic and electrical engineering. For example, it is critical in signal processing, networking, communication theory, and many other important topics. A topological index (TI) is a real number attached to graph networks and correlates the chemical networks with physical and chemical properties, as well as with chemical reactivity. In this paper, our aim is to compute degree-dependent TIs for the line graph of the Wheel and Ladder graphs. To perform these computations, we first computed M-polynomials and then from the M-polynomials we recovered nine degree-dependent TIs for the line graph of the Wheel and Ladder graphs.

Physical and Chemical Properties of Silicon Dioxide Film Deposited by New Process

1987 ◽  
Vol 105 ◽  
Author(s):  
Takuji Goda ◽  
Hirotsugu Nagayama ◽  
Akihiro Hishinuma ◽  
Hideo Kawahara
Keyword(s):  
Silicon Dioxide ◽  
Room Temperature ◽  
Etching Rate ◽  
Chemical Properties ◽  
Industrial Area ◽  
Physical And Chemical Properties ◽  
Silicon Dioxide Film ◽  
Wide Range ◽  
Physical And Chemical ◽  
And Chemical Properties

AbstractA new coating process of silicon dioxide (SiO2) “LPD” process, has been developed recently. Silicon dioxide (SiO2) film can be deposited on any substrate at the room temperature by immersing in hexafluorosilicic acid (H2SiF6).In this study, physical and chemical properties of the “LPD- SiO2” film were investigated by using XPS, IR, ellipsometry, and etch rate measurement. The properties of this film deposited at the room temperature were almost the same as those of plasma CVD. The “LPD-SiO2” film without annealing was contained traces of F and OH. However, by annealing, F and OH were rapidly evaporated from the film and the film was getting densified.As the “LPD-SiO2” film deposited at the room temperature showed very good results of chemical etching rate and of step coverage, it is expected that it is possible to use this “LPD- SiO2” film in the wide range of industrial area.

Experimental Study on the Heat Transfer in the Al Powder

2009 ◽  
Vol 83-86 ◽  
pp. 953-958
Author(s):  
Ching Yen Ho ◽  
Yu Hsiang Tsai ◽  
Mao Yu Wen
Keyword(s):  
Heat Transfer ◽  
Thermal Conduction ◽  
Room Temperature ◽  
Bulk Material ◽  
Chemical Properties ◽  
Bulk Materials ◽  
Processing Technologies ◽  
Insulating Material ◽  
Physical And Chemical ◽  
And Chemical Properties

Nanometer-sized particles possess characteristic physical and chemical properties different from those of bulk materials due to an increase in surface-to-volume ratios as well as of confinement of electrons, excitons, and photons into small volumes. Therefore it is worthwhile to discuss the thermal behaviours of powders constituted by nanometer-sized particles. The heat transfer in the powder composed of nanoparticles is experimentally investigated in this paper. The understanding for thermal properties of the powder is advantageous to the advancement of the processing technologies such as laser cladding, laser sintering, powder metallurgy and its other applications. The powder is wrapped up in the slender tube made of insulating material. One end of the slender tube filled with powder is maintained at temperature 0°C and the other end is kept at room temperature. The temperature histories at two different locations in the slender tube are recorded using thermal couples. The results show that the thermal diffusivity in the powder composed of nanoparticles is larger than that in bulk material. The pressure on the Al powders enhances the rate of heat transport due to the increase of contact area for thermal conduction.

Bulrush-Like Double Perovskite: Synthesis, Tunneling Magnetoresistance, and Magnetocaloric Effects

2008 ◽  
Vol 8 (6) ◽  
pp. 2793-2810 ◽  
Author(s):  
W. Zhong ◽  
N. J. Tang ◽  
C. T. Au ◽  
Y. W. Du
Keyword(s):  
Room Temperature ◽  
Recent Observation ◽  
Chemical Properties ◽  
Double Perovskite ◽  
Tunneling Magnetoresistance ◽  
Double Perovskites ◽  
New Approach ◽  
Half Metallic ◽  
Physical And Chemical ◽  
And Chemical Properties

The recent observation of room temperature tunneling magnetoresistance (TMR) in half-metallic A2FeMoO6 (A = Ca, Sr, Ba) double perovskites, and their importance to the emerging field of spintronics has led to considerable effort being dedicated to detailed investigations of the physical and chemical properties of these materials. This article will present an review of our recent investigations covering the synthesis, structures, magnetic and transport properties of "bulrush-like" A2FeMoO6 (A = Sr, Ba). Utilizing the high shape anisotropy as well as the reactivity of A2FeMoO6 to water and a sonochemical technique, we managed to manipulate the properties of grain boundary barriers, and thus put forward a new approach for the enhancement of room temperature TMR. The magnetocaloric effects of A2FeMoO6 double perovskites will also be discussed.

Preparation of Lignopolyols by Chemical Modification of Kraft Lignin from Oil Palm Lignocellulosic Waste

2015 ◽  
Vol 1107 ◽  
pp. 137-141
Author(s):  
Abbas Hasan Faris ◽  
Afidah Abdul Rahim ◽  
Mohamad Nasir Mohamad Ibrahim
Keyword(s):  
Oil Palm ◽  
Room Temperature ◽  
Chemical Properties ◽  
Kraft Lignin ◽  
Kraft Pulping ◽  
Lignocellulosic Waste ◽  
Alkaline Conditions ◽  
Physical And Chemical ◽  
Tga And Dsc ◽  
And Chemical Properties

The main objective of this research was to describe the thermal and chemical characteristics of lignopolyols. Lignin was extracted from oil palm empty fruit bunch after kraft pulping process. Oxypropylation reaction was achieved by reacting kraft lignin with propylene oxide under alkaline conditions at room temperature. The physical and chemical properties of lignopolyols were evaluated by FTIR, NMR, GPC, TGA, and DSC. Lignopolyol exhibited higher chemical activity than kraft lignin. The polyols used as precursors in biomass-based wood adhesives preparation demonstrated promising results. Keywords: kraft lignin, lignopolyol, oxypropylation, NMR spectroscopy, DSC

Synthesis of AC60-Para-Xylylene Copolymer

1992 ◽  
Vol 247 ◽  
Author(s):  
Douglas A. Loy ◽  
Roger A. Assink
Keyword(s):  
Free Radical ◽  
Room Temperature ◽  
Chemical Properties ◽  
Gravimetric Analysis ◽  
Physical And Chemical Properties ◽  
Thermal Gravimetric ◽  
Green Solution ◽  
Physical And Chemical ◽  
And Chemical Properties ◽  
Brown Powder

ABSTRACTThe preparation and purification of macroscopic quantities of buckminsterfullerenes [1] or buckyballs has ignited an explosion of research into their physical and chemical properties, and a variety of strategies for preparing new fullerene-based materials. Free radical synthesis is an appealing approach for forming polymeric fullerene materials. We report a polymeric fullerene material prepared by reacting pure C60 with xylylene from the thermolysis of paracyclophane. Addition of xylylene to a purple solution of C60 in toluene solution at -78 °C resulted in an olive-green solution from which an insoluble brown powder precipitated upon warming to room temperature. Analyses of the powder by solid state 13C MAS NMR, IR, and thermal gravimetric analysis are consistent with C60-xylylene copolymer.

Research on physico-chemical properties of sugars and sugar crystallization at the University of Chemistry and Technology in Prague

2020 ◽  
pp. 294-298
Author(s):  
Z. Bubnik ◽  
P. Kadlec ◽  
E. Sarka ◽  
V. Pour ◽  
A. Hinkova ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Main Research ◽  
Research Areas ◽  
Research Activities ◽  
Physico Chemical ◽  
Wide Range ◽  
The University ◽  
Physical And Chemical ◽  
Kinetics Of ◽  
And Chemical Properties

This paper represents a summary of most important research activities in sucrose crystallization, in which the Department of Carbohydrates and Cereals, part of the University of Chemistry and Technology (UCT) Prague, has been involved over the last 25 years. A wide range of these projects has been carried out in cooperation with other research institutes, universities and industrial partners. These activities can be divided into four main research areas that are interconnected and support each other. – Physical and chemical properties of sucrose and sugar solutions; – Growth kinetics of sugar crystals in pure and technical sugar solutions; – Simulation and mathematical modeling of new processes and technologies; – Experimental work for industry and cooperation with industrial partners.

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