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Article

Karel Král and Miroslav Menšík

In this work the experimental effect of a slow decay of the photoluminescence is studied theoretically in the case of quantum dots with an indirect energy band gap. The…

Abstract

In this work the experimental effect of a slow decay of the photoluminescence is studied theoretically in the case of quantum dots with an indirect energy band gap. The slow decay of the photoluminescence is considered as decay in time of the luminescence intensity, following the excitation of the quantum dot sample electronic system by a short optical pulse. In the presented theoretical treatment the process is studied as a single dot property. The inter-valley deformation potential interaction of the excited conduction band electrons with lattice vibrations is considered in the self-consistent Born approximation to the electronic self-energy. The theory is built on the non-equilibrium electronic quantum transport theory. The time dependence of the photoluminescence decay is estimated upon using a simple effective mass model. The numerical calculation of the considered model shows the power-law time characteristics of the photoluminescence decay in the long-time limit of the decay. We demonstrate that the nonadiabatic influence of the interaction of the conduction band electrons with the lattice vibrations provides a mechanism giving us the power-law time dependence of the photoluminescence intensity signal. This theoretical result emphasizes the role of the electron-phonon interaction in the nanostructures.

Details

World Journal of Engineering, vol. 11 no. 5
Type: Research Article
ISSN: 1708-5284

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Article

Cao Junfeng

Through many years of study, we have found that cold quantum is the most important force in nature. Under the pressure of coldness on hotness, various materials are…

Abstract

Through many years of study, we have found that cold quantum is the most important force in nature. Under the pressure of coldness on hotness, various materials are formed. Under the pressure of cold quantum, these materials are provided with gravity, and celestial bodies start to move. The pressure of cold quantum exists in space and materials. It is the pressure of cold quantum that huge changes between the four seasons on the earth begin to appear. The whirlpool, produced from the cold quantum pressure, pushes all the celestial bodies making them turn and change. The coldness converts frozen water into ice, which could not be achieved by any other force. The extreme and powerful strength of cold quantum has been well‐known. Therefore, we claim that the cold quantum pressure is the greatest force which ever existed in the universe.

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Kybernetes, vol. 32 no. 7/8
Type: Research Article
ISSN: 0368-492X

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Abstract

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Sensor Review, vol. 24 no. 3
Type: Research Article
ISSN: 0260-2288

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Article

Sankit Kassa, Prateek Gupta, Manoj Kumar, Thompson Stephan and Ramani Kannan

In nano-scale-based very large scale integration technology, quantum-dot cellular automata (QCA) is considered as a strong and capable technology to replace the well-known…

Abstract

Purpose

In nano-scale-based very large scale integration technology, quantum-dot cellular automata (QCA) is considered as a strong and capable technology to replace the well-known complementary metal oxide semiconductor technology. In QCA technique, rotated majority gate (RMG) design is not explored greatly, and therefore, its advantages compared to original majority gate are unnoticed. This paper aims to provide a thorough observation at RMG gate with its capability to build robust circuits.

Design/methodology/approach

This paper presents a new methodology for structuring reliable 2n-bit full adder (FA) circuit design in QCA utilizing RMG. Mathematical proof is provided for RMG gate structure. A new 1-bit FA circuit design is projected here, which is constructed with RMG gate and clock-zone-based crossover approach in its configuration.

Findings

A new structure of a FA is projected in this paper. The proposed design uses only 50 number of QCA cells in its implementation with a latency of 3 clock zones. The proposed 1-bit FA design conception has been checked for its structure robustness by designing various 2, 4, 8, 16, 32 and 64-bit FA designs. The proposed FA designs save power from 46.87% to 25.55% at maximum energy dissipation of circuit level, 39.05% to 23.36% at average energy dissipation of circuit-level and 42.03% to 37.18% at average switching energy dissipation of circuit level.

Originality/value

This paper fulfills the gape of focused research for RMG with its detailed mathematical modeling analysis.

Details

Circuit World, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0305-6120

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Article

Kumar S. Ray and Piyali Chatterjee

The purpose of this paper is to propose an alternative approach to approximate reasoning by DNA computing, thereby adding a new dimension to the existing approximate…

Abstract

Purpose

The purpose of this paper is to propose an alternative approach to approximate reasoning by DNA computing, thereby adding a new dimension to the existing approximate reasoning method by bringing it down to nanoscale computing. The logical aspect of approximate reasoning is replaced by DNA chemistry.

Design/methodology/approach

To achieve this goal, first the synthetic DNA sequence fuzzified by quantum dot, which is a recent advancement of nanotechnology. Thus with the help of fuzzy DNA, which holds the vague concept of human reasoning, the basic method of approximate reasoning on a DNA chip is realized. This approach avoids the tedious choice of a suitable implication operator (for a particular application) necessary for existing approximate reasoning based on fuzzy logic. The inferred consequences obtained from DNA computing‐based approximate reasoning is ultimately hybridized with appropriate complementary sequence probed on a DNA‐chip to confirm the result of inference.

Findings

The present approach is suitable for reasoning under vague and uncertain environment and does not require any subject choice of any individual expert, which is essential for existing approximate reasoning method.

Originality/value

This new tool for approximate reasoning based on DNA computing is applicable to several problems of science and engineering; namely pattern classification, control theory, weather forecasting, atmospheric science, etc.

Details

International Journal of Intelligent Computing and Cybernetics, vol. 3 no. 3
Type: Research Article
ISSN: 1756-378X

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Article

Whilst at the Department of Computer Science at Columbia University, US, Michael Lebowitz, currently at the Analytical Proprietary Trading Unit of Morgan Stanley and

Abstract

Whilst at the Department of Computer Science at Columbia University, US, Michael Lebowitz, currently at the Analytical Proprietary Trading Unit of Morgan Stanley and Company, New York, researched into a variety of areas in natural language processing and machine learning. In particular his UNIMEM learning program has been applied to a wide range of domains including census data, software evaluation and congressional voting records. In a recent research contribution, “The Use of Memory in Text Processing”, Communications of the ACM, Vol. 31 No. 12, 1988, pp. 1483–1505, he describes how RESEARCHER, a program that reads, remembers and generalises from patent abstracts, makes use of its automatically generated memory to assist low‐level text processing. This, he says, involves disambiguation that could be accomplished in no other way.

Details

Kybernetes, vol. 18 no. 2
Type: Research Article
ISSN: 0368-492X

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Article

Klaus Schroeter

This paper aims to discuss the new applications enabled by printed sensors.

Abstract

Purpose

This paper aims to discuss the new applications enabled by printed sensors.

Design/methodology/approach

The paper discusses how silicon‐based sensors are manufactured using the time‐consuming, expensive, and complicated fabrication process of traditional semiconductor devices and shows what is needed in order to produce such new devices with the advantages of printed sensors.

Findings

With new materials, new processing technologies and a new manufacturing process, thin, flexible, lightweight, cost‐effective sensors are made possible through the power of printed semiconductors.

Originality/value

This paper should be of value in terms of understanding the pros of printed semiconductors and the resulting sensors which have a number of unique mechanical, electrical, and optical properties.

Details

Sensor Review, vol. 28 no. 1
Type: Research Article
ISSN: 0260-2288

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Article

Ehsan Jafarnejad, Jafar Abolhasani and Arezoo Derakhshan

This study aims to develop a new simple and sensitive method for the microextraction of trace levels of lead in environmental samples. It is based on the use of ionic…

Abstract

Purpose

This study aims to develop a new simple and sensitive method for the microextraction of trace levels of lead in environmental samples. It is based on the use of ionic liquids based dispersive liquid–liquid microextraction (IL–DLLME) before spectrofluorometry.

Design/methodology/approach

Cadmium sulphide quantum dots have been synthesised using thioglycolic acid as capping agent through a one-step process with stability and excellent water-solubility, and have strong affinity for lead (Pb). This probe is based on the fluorescence quenching effect of functionalised cadmium sulphide quantum dots.

Findings

Factors affecting the extraction efficiency and fluorescence quenching of metals, such as the amount of ionic liquid, amount of metanol, microextraction and centrifugation time, volume of quantum dots and buffer pH, were investigated. Under optimum conditions, the calibration graph was linear in the range of 0.01-3 µg.L-1, with the detection limit of 0.004 µg.L-1 for Pb2+. The relative standard deviation (RSD%, n = 5) of 5.4 per cent at 1 µg.L-1 of Pb2+ was obtained.

Originality/value

This method for pre-concentration of the Pb ions by dispersive liquid–liquid microextraction is novel and could be used for various applications in the synthesis of a wide variety of determination of fluorescence quenching of cadmium sulphide quantum dots.

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Article

Chunjuan Luan and Xiuping Wang

The purpose of this paper is to help China's science and technology (abbr. as S&T) managers and related policy makers to allocate S&T human resources, optimize…

Abstract

Purpose

The purpose of this paper is to help China's science and technology (abbr. as S&T) managers and related policy makers to allocate S&T human resources, optimize organizational systems of laboratories, design and plan some grant projects, and manage other S&T‐related work in the field of nanoscience and nanotechnology, by measuring and mapping of technology‐fields correlation, with nanotechnology as an example.

Design/methodology/approach

Methodologies such as co‐occurrence analysis, correlation analysis, multidimensional scaling (abbr. as MDS) analysis, dendrogram (tree‐like) analysis, etc. are employed to measure and map technology‐fields correlation.

Findings

It is found that the exact relevance degree of any two technology‐fields exists among the top 33 technology‐fields with high frequencies. There are three industrial clusters in Multidimentional Scaling View, that is, nanotechnology used in bio‐medical industry, nanotechnology used in new material industry and nanotechnology used in electronic industry. Hierarchy of any two technology‐fields can be found out in the dendrogram view of the top 33 technology‐fields.

Originality/value

This paper could be of great significance to China's S&T managers and related policy makers, especially in the area of nanotechnology, in selecting and managing generic technology and the findings in this paper can be applied in some other fields of science and technology management in China. Both technology‐fields correlation analysis and MDS and dendrogram view analysis could benefit China's policy makers in managing nanotechnology research and development activities.

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Article

Zhiwei Li

The purpose of this paper is to find an effective route to fabricate high transparent top electrode in quantum dots light-emitting diodes (QLEDs).

Abstract

Purpose

The purpose of this paper is to find an effective route to fabricate high transparent top electrode in quantum dots light-emitting diodes (QLEDs).

Design/methodology/approach

Al-doped ZnO (AZO) top cathode with high transparency have been deposited by an atomic layer deposition (ALD) method at 140°C for 1 h. The products are studied by UV-vis spectrometer and atomic force microscopy (AFM). The electroluminescence spectra of QLED are recorded using an Ocean Optics high-resolution spectrometer (HR4000). The devices were measured under ambient conditions without encapsulation.

Findings

The AZO-based QLED shows excellent performance with high luminance and current efficiency.

Originality/value

The AZO obtained by ALD method is a promising cathode candidate for application in QLEDs.

Details

Microelectronics International, vol. 35 no. 4
Type: Research Article
ISSN: 1356-5362

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