scholarly journals Recent developments in electrospun ZnO nanofibers: A short review

2020 ◽  
Vol 15 ◽  
pp. 155892501989968 ◽  
Author(s):  
Tomasz Blachowicz ◽  
Andrea Ehrmann
Keyword(s):  
Gas Sensing ◽  
Short Review ◽  
Zinc Nitrate ◽  
Ethanol Solution ◽  
Treatment Techniques ◽  
Polymer Semiconductor ◽  
Recent Developments ◽  
Broad Variety ◽  
Zno Nanofibers ◽  
Nanofiber Mats

Especially for the potential use as sensors, but also in all other applications in which an interaction with the environment occurs, nanofibrous materials are advantageous due to their large specific surface area. An interesting material for electrospinning is the semiconductor zinc oxide (ZnO) which is often used in photoelectric or sensory applications. Nanofibers containing ZnO can be produced, for example, by electrospinning polyvinylpyrrolidone/zinc nitrate from a dimethylformamide/ethanol solution, followed by calcination to remove the organic phase. Alternatively, the polymer/semiconductor blended nanofibers can be used which are often less brittle, but on the other hand offer less contact between ZnO and the environment. Finally, decorating a nanofiber mat with ZnO offers another possibility to prepare nanofibers with ZnO surface. Possible applications of electrospun ZnO nanofibers or nanofiber mats include gas sensing, microwave absorption, photocatalytic degradation or enhancement of supercapacitor electrodes. This short review gives an overview of the most recent electrospinning and after-treatment techniques to create pure and blended ZnO nanofibers and presents the broad variety of possible applications of this well-known semiconductor with some still surprising properties.

scholarly journals Conductive Electrospun Nanofiber Mats

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 152 ◽  
Author(s):  
Tomasz Blachowicz ◽  
Andrea Ehrmann
Keyword(s):  
Conductive Polymers ◽  
Conductive Polymer ◽  
Electrospinning Process ◽  
Electrospun Nanofiber ◽  
Conductive Coatings ◽  
Molecular Weights ◽  
Calcination Step ◽  
Recent Developments ◽  
Broad Variety ◽  
Nanofiber Mats

Conductive nanofiber mats can be used in a broad variety of applications, such as electromagnetic shielding, sensors, multifunctional textile surfaces, organic photovoltaics, or biomedicine. While nanofibers or nanofiber from pure or blended polymers can in many cases unambiguously be prepared by electrospinning, creating conductive nanofibers is often more challenging. Integration of conductive nano-fillers often needs a calcination step to evaporate the non-conductive polymer matrix which is necessary for the electrospinning process, while conductive polymers have often relatively low molecular weights and are hard to dissolve in common solvents, both factors impeding spinning them solely and making a spinning agent necessary. On the other hand, conductive coatings may disturb the desired porous structure and possibly cause problems with biocompatibility or other necessary properties of the original nanofiber mats. Here we give an overview of the most recent developments in the growing field of conductive electrospun nanofiber mats, based on electrospinning blends of spinning agents with conductive polymers or nanoparticles, alternatively applying conductive coatings, and the possible applications of such conductive electrospun nanofiber mats.

Schottky diodes based on 2D materials for environmental gas monitoring: a review on emerging trends, recent developments and future perspectives

2021 ◽  
Author(s):  
Minu Mathew ◽  
Chandra Sekhar Rout
Keyword(s):  
Gas Sensing ◽  
2D Materials ◽  
Schottky Diodes ◽  
High Sensitivity ◽  
Future Perspectives ◽  
Working Temperature ◽  
Emerging Trends ◽  
Gas Sensing Properties ◽  
Recent Developments ◽  
Sensitivity And Selectivity

This review details the fundamentals, working principles and recent developments of Schottky junctions based on 2D materials to emphasize their improved gas sensing properties including low working temperature, high sensitivity, and selectivity.

scholarly journals Fabrication of Transition-metal (Zn, Mn, Cu)-based MOFs as Efficient Sensor Materials for Detection of H2 Gas by Clad Modified Fiber Optic Gas Sensor Technique

2021 ◽  
Author(s):  
M Nagoor Meeran ◽  
S.P. Saravanan ◽  
H.H Hegazy
Keyword(s):  
Transition Metal ◽  
Fiber Optic ◽  
Gas Sensing ◽  
High Sensitivity ◽  
Long Term Stability ◽  
Sensing Material ◽  
Sensor Technique ◽  
Recent Developments ◽  
Metal Organic ◽  
Elevated Surface

Abstract Recent research demonstrate that promising gas sensing materials are called metal-organic structures (MOFs) and their products due to their tunable form, elevated surface area, and extremely porous structure and physisorption towards gases with relatively low temperature.In this report, recent developments in transition-metal (Zn, Mn, Cu)-based MOFs and their derivatives are synthesized as sensing materials. The sensors samples were analyzed by XRD, SEM, TEM, BET and XPS in order to know the textural, structural and electronic state of the samples. Fiber optic clad modified sensors were fabricated and tested gas sensing properties towards H2 gas with various concentrations (0-1000 ppm). Among the three sensing material, Zn doped MOFs sensor showed outstanding selectivity with high sensitivity (115 counts/kpa) towards H2 gas. Moreover, it has shown high response (20 s) and recovery time (27 s) as well as long term stability. The designed sensors may be required to apply to the production of an outstanding sensor for H2 for commercial uses.

Thinks tanks and their role in policy making in ireland

2021 ◽  
pp. 157-170
Author(s):  
Chris McInerney
Keyword(s):  
Public Policy ◽  
Civil Society ◽  
Policy Making ◽  
International Experience ◽  
Think Tanks ◽  
Think Tank ◽  
Complex Issue ◽  
Recent Developments ◽  
Broad Variety

This chapter reviews the role of think tanks in policy making. Like most modern democracies, Ireland relies on a range of sources to influence the choices and designs of public policy. Apart from political and administrative influences, a broad variety of civil society, academic and private sector actors seek to access, influence, advise, inform and sometimes embarrass those in power. The chapter focuses on ‘think tanks’, defining them, reviewing international experience, examining different types and considering the complex issue of assessing think tank influence. It maps out Ireland’s limited think tank landscape and examines recent developments. Think tanks’ influence on Irish policymaking is assessed across a number of indicators.

Recent Developments in C–C Bond Formation Using Catalytic Reductive Coupling Strategies

Synthesis ◽  
2020 ◽  
Vol 52 (18) ◽  
pp. 2623-2638
Author(s):  
Joshua D. Sieber ◽  
Toolika Agrawal
Keyword(s):  
Bond Formation ◽  
Cross Coupling ◽  
Short Review ◽  
Reductive Coupling ◽  
Recent Developments ◽  
Molecular Complexity ◽  
Metal Catalyzed ◽  
Coupling Processes ◽  
Coupling Strategies

Metal-catalyzed reductive coupling processes have emerged as a powerful methodology for the introduction of molecular complexity from simple starting materials. These methods allow for an orthogonal approach to that of redox-neutral strategies for the formation of C–C bonds by enabling cross-coupling of starting materials not applicable to redox-neutral chemistry. This short review summarizes the most recent developments in the area of metal-catalyzed reductive coupling utilizing catalyst turnover by a stoichiometric reductant that becomes incorporated in the final product.1 Introduction2 Ni Catalysis3 Cu Catalysis4 Ru, Rh, and Ir Catalysis4.1 Alkenes4.2 1,3-Dienes4.3 Allenes4.4 Alkynes4.5 Enynes5 Fe, Co, and Mn Catalysis6 Conclusion and Outlook

scholarly journals Quaternary Misfit Compounds—A Concise Review

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 468
Author(s):  
Sokhrab B. Aliev ◽  
Reshef Tenne
Keyword(s):  
Irrational Number ◽  
Short Review ◽  
Layered Compounds ◽  
Layered Compound ◽  
Charge Carrier Density ◽  
Precise Control ◽  
Rocksalt Structure ◽  
Main Emphasis ◽  
Recent Developments ◽  
Metal Dichalcogenides

Misfit layered compounds (MLCs) have been studied in the literature for the last 40 years. They are generally made of an alternating sequence of two monolayers, a distorted rocksalt structure, and a hexagonal layered compound. In a typical MLC, the c-axis is common to the two monolayers and so is one of the axes in the layer plan. However, the two compounds are non-commensurate along at least one axis, and the ratio between the two axes is an irrational number making the MLC a non-stoichiometric compound. The two main families of MLC are those based on metal dichalcogenides and CoO2 as the hexagonal layered compound. Traditionally, ternary MLCs were prepared and studied, but some quaternary and multinary MLC minerals have been known for many years. Over the last few years, interest in MLCs with four and even larger number of atoms has grown. Doping or alloying of a ternary MLC permits precise control of the charge carrier density and hence the electrical, thermoelectric, catalytic, and optical properties of such compounds. In this short review, some of these developments will be discussed with the main emphasis put on quaternary MLC nanotubes belonging to the chalcogenide series. The synthesis, structural characterization, and some of their properties are considered. Some recent developments in quaternary cobaltite MLCs and recent studies on exfoliated MLCs are discussed as well.

NANOSILICON FOR PHOTONIC APPLICATIONS

2007 ◽  
Vol 21 (22) ◽  
pp. 3783-3796 ◽  
Author(s):  
S. K. GHOSHAL ◽  
DEVENDRA MOHAN ◽  
TADESSE TENAW KASSA ◽  
SUNITA SHARMA
Keyword(s):  
Gas Sensing ◽  
Intrinsic Property ◽  
Photo Luminescence ◽  
Short Review ◽  
Two Dimensions ◽  
Basic Question ◽  
Nano Technology ◽  
Light Amplification ◽  
Photon Confinement ◽  
Low Dimensional

This presentation is a short review of some scientific insights on the possibilities of photonic applications of nanostructured silicon ( NS – Si ), porous Si ( p - Si ) and Si nanocrystals ( NC – Si ), one of the most interesting problems in nano-crystallite physics. The emission mechanism of a very bright photo-luminescence (PL) band and relatively weak electro-luminescence (EL) are presently the main issue. The basic question lies in whether the emission is an extrinsic or intrinsic property of nanocrystals. It is important from a fundamental physics viewpoint because of the potential application of Si wires and quantum dots in optoelectronic devices and information technology. Nanostructuring silicon is an effective way to turn silicon into a photonic material. It is observed that low-dimensional (one and two dimensions) silicon shows light amplification, photon confinement, photon trapping as well as non-linear optical effects. There is strong evidence of light localization and gas sensing properties of such nanostructures. Future nano-technology would replace electrical with optical interconnects, which has appealing potential for higher-speed performance and immunity to signal cross talk.

scholarly journals THE INTERFACE OF COSMOLOGY WITH STRING AND M(ILLENNIUM) THEORY

2001 ◽  
Vol 16 (30) ◽  
pp. 4803-4843 ◽  
Author(s):  
DAMIEN A. EASSON
Keyword(s):  
Early Universe ◽  
Extra Dimensions ◽  
Large Extra Dimensions ◽  
Short Review ◽  
Big Bang ◽  
Space Time ◽  
String Cosmology ◽  
Brane World ◽  
Recent Developments ◽  
M Theory

The purpose of this review is to discuss recent developments occurring at the interface of cosmology with string and M theory. We begin with a short review of 1980s string cosmology and the Brandenberger–Vafa mechanism for explaining space–time dimensionality. It is shown how this scenario has been modified to include the effects of p-brane gases in the early universe. We then introduce the Pre-Big-Bang scenario (PBB), Hořava–Witten heterotic M theory and the work of Lukas, Ovrut and Waldram, and end with a discussion of large extra dimensions, the Randall–Sundrum model and Brane World cosmologies.

Client Information Handout Reprinted from Pet Focus, with Permission

1991 ◽  
Vol 8 (2) ◽  
pp. 26-30 ◽  
Author(s):  
Kenneth F. Lyon
Keyword(s):  
Health Care ◽  
Dental Care ◽  
The Past ◽  
Treatment Techniques ◽  
Recent Developments ◽  
New Treatment

Today, it is recognized that our pets have dental problems that went unrecognized and untreated in the past. Recent developments in the field of veterinary dentistry, increased owner awareness, and new treatment techniques make dental care an indispensable part of pet health care. Routine preventative procedures such as brushing the teeth should be a regular aspect of the care we extend to our pets. J. Vet. Dent., 1991; 8(2): 26–30.

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