Fascinating World of Nanomaterials, Applications and Technology Hurdles in Commercial Production

2009 ◽  
Vol 1209 ◽  
Author(s):  
Shiva Hullavarad ◽  
Nilima Hullavarad

AbstractNanoparticles, nanowires, nanorods and other kinds of nanostructures have been of great interest to scientific field. Semiconducting nanowires have attracted much attention due to the fact that reduced dimensional confinement of electrons, holes and photons make them particularly attractive as potential building blocks for nanoscale optoelectronic devices, highly quantum efficient lasers and non-linear optical converters. It is generally accepted that the low dimensional structures (where the size in one direction is equivalent to or smaller than the de Broglie wavelength) are useful materials for investigating the dependence of electrical and thermal transport or mechanical properties on the dimensionality and quantum confinement. Nanomaterials also play an important role as functional units in fabricating the electromechanical devices. Semiconductor nanostructures of different materials and shapes are investigated due to their size dependent electronic properties observable at dimensions comparable to or less than Bohr radius of exciton in these materials. Especially various oxides and sulphides have generated interests in variety of applications. In this paper, the recent progress in various nanostructures, paradigms in implementation and technology hurdles in implementing nanostructures are discussed

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Neelima Agarwal ◽  
Lorenzo Magnea ◽  
Sourav Pal ◽  
Anurag Tripathi

Abstract Correlators of Wilson-line operators in non-abelian gauge theories are known to exponentiate, and their logarithms can be organised in terms of collections of Feynman diagrams called webs. In [1] we introduced the concept of Cweb, or correlator web, which is a set of skeleton diagrams built with connected gluon correlators, and we computed the mixing matrices for all Cwebs connecting four or five Wilson lines at four loops. Here we complete the evaluation of four-loop mixing matrices, presenting the results for all Cwebs connecting two and three Wilson lines. We observe that the conjuctured column sum rule is obeyed by all the mixing matrices that appear at four-loops. We also show how low-dimensional mixing matrices can be uniquely determined from their known combinatorial properties, and provide some all-order results for selected classes of mixing matrices. Our results complete the required colour building blocks for the calculation of the soft anomalous dimension matrix at four-loop order.


2015 ◽  
Vol 17 (19) ◽  
pp. 12833-12840 ◽  
Author(s):  
Arpan Bhattacharya ◽  
Surajit Chatterjee ◽  
Roopali Prajapati ◽  
Tushar Kanti Mukherjee

Size-dependent penetration of CDs through the ferritin channels has been successfully demonstrated by means of λex-dependent PL quenching of CDs by the Fe3+ ions of ferritin.


1992 ◽  
Vol 01 (04) ◽  
pp. 683-698 ◽  
Author(s):  
YING WANG ◽  
NORMAN HERRON

We report the third-order nonlinear susceptibilities χ(3) of CdS clusters (quantum dots) from 7 to 120 Å, measured by third-harmonic generation technique at a fundamental wavelength of 1.91 µm. In the size regime studied, the value of χ(3) first increases with cluster size and then levels off for cluster diameter larger than 60 Å. The volume normalized χ(3) of CdS cluster is about a factor of 2 higher than that of the bulk. These data can be explained by the enhancement in electric field inside the clusters due to the dielectric confinement effect. The size and wavelength dependences of this local field effect have been calculated for CdS clusters. Several trends in the nonresonant χ(3) can be identified: (i) In the absence of quantum confinement effect, the magnitude of χ(3) should be constant in the < 200 Å size regime. It then increases with increasing particle size until the structural resonance regime is reached. (ii) The magnitude of χ(3) can be enhanced by either lowering the refractive index of the surrounding medium or raising the refractive index of the semiconductors. (iii) Quantum confinement, which shifts the band gap to the blue and lowers the refractive index of the semiconductor clusters, reduces the nonresonant χ(3). This is in direct contrast to the resonant nonlinearity which is enhanced by the quantum-confinement effect. Finally, we discuss the size-dependent figure-of-merit of CdS composites for all-optical switching.


2004 ◽  
Vol 59 (8) ◽  
pp. 869-876 ◽  
Author(s):  
L. Engelke ◽  
R. Stähler ◽  
M. Schur ◽  
C. Näther ◽  
W. Bensch ◽  
...  

AbstractThe two new compounds Mn2(L)Sb2S5 (L = diethylenetriamine = DIEN, N-methyl-1,3- diaminopropane = MDAP) were prepared under solvothermal conditions using the elements as starting materials. Both compounds crystallise in the monoclinic space group P21/c with the lattice parameters a=10.669(7), b=12.805(2), c=12.072(1)Å , β =115.786(7)°,V =1485.1(4) Å3 for L = DIEN and a = 10.1859(7), b = 12.7806(6), c = 12.1256(8)Å , β = 110.173(8)°, V = 1481.7(2) Å3 for L = MDAP and Z = 4. The primary building units are SbS3 pyramids, MnS6 and MnS4N2 distorted octahedra. These primary building blocks are interconnected to form Mn2Sb2S4 hetero-cubane units. The hetero-cubanes share common corners, edges and faces thus forming a second heterocubane. These secondary building units are joined to form layers within the (100) plane. The connection mode yields ellipsoidal pores within the layers. The amines are exclusively bound to one of the two crystallographically independent Mn2+ cations and they point into the pores and between the layers separating the layers from each other. The interlayer separation and the size of the pores depend on the sterical requirements of the amine incorporated into the network. A pronounced distortion of the MnS4N2 octahedron results from a significant elongation of one Mn-S distance from 2.866 Å (L = methylamine, MA) to 3.185 Å for L = MDAP. The magnetic susceptibility curves are typical for low-dimensional antiferromagnetic materials and the large negative values for the Weiss constant Θ indicate strong antiferromagnetic exchange interactions. The magnetic properties are significantly influenced by the change of the Mn-S bonds introduced by the different amines. The compounds decompose at elevated temperatures with a two step reaction for L = MA and ethylenediamine and in a one step reaction for the bidentate acting amine molecules.


Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 866
Author(s):  
Merve Kortel ◽  
Bhargav D. Mansuriya ◽  
Nicole Vargas Santana ◽  
Zeynep Altintas

Graphene quantum dots (GQDs) are considerably a new member of the carbon family and shine amongst other members, thanks to their superior electrochemical, optical, and structural properties as well as biocompatibility features that enable us to engage them in various bioengineering purposes. Especially, the quantum confinement and edge effects are giving GQDs their tremendous character, while their heteroatom doping attributes enable us to specifically and meritoriously tune their prospective characteristics for innumerable operations. Considering the substantial role offered by GQDs in the area of biomedicine and nanoscience, through this review paper, we primarily focus on their applications in bio-imaging, micro-supercapacitors, as well as in therapy development. The size-dependent aspects, functionalization, and particular utilization of the GQDs are discussed in detail with respect to their distinct nano-bio-technological applications.


2020 ◽  
Vol 34 (18) ◽  
pp. 2050168
Author(s):  
Fei Feng ◽  
Fengdong Lv ◽  
Gongping Zheng ◽  
Guangtao Wang

We used the first principle of density functional theory to perform detailed calculations regarding the structure, and the electronic and magnetic properties of MX (M[Formula: see text]=[Formula: see text]Ga, In; X[Formula: see text]=[Formula: see text]S, Se, Te) nanoribbons. The armchair nanoribbons (ARNs) are nonmagnetic semiconductors, which have even or odd oscillations of bandgaps. All small-sized zigzag nanoribbons (ZRNs) were found to break the six-membered ring structure and move to the center, thereby exhibiting nonmagnetic semiconductor behavior owing to the quantum confinement effect. However, among the large ZRNs, which are all metals, MTe ZRNs are nonmagnetic; this differs from the case of graphene, MoS2 and Ti2CO2 nanoribbons. MX (M[Formula: see text]=[Formula: see text]Ga, In; X[Formula: see text]=[Formula: see text]S, Se) ZRNs exhibited ferromagnetism owing to the presence of the unpaired electrons on the metal-edge side and the magnetic moment of each pair of molecules, which was controlled by the size of the nanoribbons. The results provided a theoretical reference that can be used in the future to produce MX materials for application in low-dimensional semiconductor devices, spin electron transport devices and new magnetoresistance devices.


2020 ◽  
Vol 860 ◽  
pp. 1-26 ◽  
Author(s):  
Zhongwei Zhang ◽  
Yulou Ouyang ◽  
Yuan Cheng ◽  
Jie Chen ◽  
Nianbei Li ◽  
...  

2020 ◽  
Vol 152 (11) ◽  
pp. 110902 ◽  
Author(s):  
James Cassidy ◽  
Mikhail Zamkov

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