Applied Sciences

1895 KiB

Open AccessArticle

Effect of RhOx/CeO₂ Calcination on Metal-Support Interaction and Catalytic Activity for N₂O Decomposition

by Verónica Rico-Pérez and Agustin Bueno-López

Appl. Sci. 2014, 4(3), 468-481; https://doi.org/10.3390/app4030468 - 22 Sep 2014

Cited by 15 | Viewed by 7391

The effect of the calcination conditions on the catalytic activity for N₂O decomposition of 2.5% RhOx/CeO₂ catalysts has been investigated. Ramp and flash calcinations have been studied (starting calcinations at 25 or 250/350 °C, respectively) both for cerium nitrate and [...] Read more.

The effect of the calcination conditions on the catalytic activity for N₂O decomposition of 2.5% RhOx/CeO₂ catalysts has been investigated. Ramp and flash calcinations have been studied (starting calcinations at 25 or 250/350 °C, respectively) both for cerium nitrate and ceria-impregnated rhodium nitrate decomposition. The cerium nitrate calcination ramp has neither an effect on the physico-chemical properties of ceria, observed by XRD, Raman spectroscopy and N₂ adsorption, nor an effect on the catalysts performance for N₂O decomposition. On the contrary, flash calcination of rhodium nitrate improved the catalytic activity for N₂O decomposition. This is attributed to the smaller size of RhOx nanoparticles obtained (smaller than 1 nm) which allow a higher rhodium oxide-ceria interface, favoring the reducibility of the ceria surface and stabilizing the RhOx species under reaction conditions. Full article

(This article belongs to the Special Issue Feature Papers)

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2236 KiB

Open AccessReview

Tunable Multicolored Femtosecond Pulse Generation Using Cascaded Four-Wave Mixing in Bulk Materials

by Jinping He, Jun Liu and Takayoshi Kobayashi

Appl. Sci. 2014, 4(3), 444-467; https://doi.org/10.3390/app4030444 - 22 Sep 2014

Cited by 8 | Viewed by 7164

Abstract

This paper introduces and discusses the main aspects of multicolored femtosecond pulse generation using cascaded four-wave mixing (CFWM) in transparent bulk materials. Theoretical analysis and semi-quantitative calculations, based on the phase-matching condition of the four-wave mixing process, explain the phenomena well. Experimental studies, [...] Read more.

This paper introduces and discusses the main aspects of multicolored femtosecond pulse generation using cascaded four-wave mixing (CFWM) in transparent bulk materials. Theoretical analysis and semi-quantitative calculations, based on the phase-matching condition of the four-wave mixing process, explain the phenomena well. Experimental studies, based on our experiments, have shown the main characteristics of the multicolored pulses, namely, broadband spectra with wide tunability, high stability, short pulse duration and relatively high pulse energy. Two-dimensional multicolored array generation in various materials are also introduced and discussed. Full article

(This article belongs to the Special Issue Multi-Color Laser Emission for the Generation of Ultrashort Optical Pulse)

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4937 KiB

Open AccessReview

Towards Laser Driven Hadron Cancer Radiotherapy: A Review of Progress

by Ken W. D. Ledingham, Paul R. Bolton, Naoya Shikazono and C.-M. Charlie Ma

Appl. Sci. 2014, 4(3), 402-443; https://doi.org/10.3390/app4030402 - 19 Sep 2014

Cited by 101 | Viewed by 16059

Abstract

It has been known for about sixty years that proton and heavy ion therapy is a very powerful radiation procedure for treating tumors. It has an innate ability to irradiate tumors with greater doses and spatial selectivity compared with electron and photon therapy [...] Read more.

It has been known for about sixty years that proton and heavy ion therapy is a very powerful radiation procedure for treating tumors. It has an innate ability to irradiate tumors with greater doses and spatial selectivity compared with electron and photon therapy and, hence, is a tissue sparing procedure. For more than twenty years, powerful lasers have generated high energy beams of protons and heavy ions and it has, therefore, frequently been speculated that lasers could be used as an alternative to radiofrequency (RF) accelerators to produce the particle beams necessary for cancer therapy. The present paper reviews the progress made towards laser driven hadron cancer therapy and what has still to be accomplished to realize its inherent enormous potential. Full article

(This article belongs to the Special Issue Casting Light on Cancer Therapy)

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5516 KiB

Open AccessArticle

Effect of Two-Photon Stark Shift on the Multi-Frequency Raman Spectra

by Hao Yan and Donna Strickland

Appl. Sci. 2014, 4(3), 390-401; https://doi.org/10.3390/app4030390 - 5 Sep 2014

Cited by 8 | Viewed by 17418

Abstract

High order Raman generation has received considerable attention as a possible method for generating ultrashort pulses. A large number of Raman orders can be generated when the Raman-active medium is pumped by two laser pulses that have a frequency separation equal to the [...] Read more.

High order Raman generation has received considerable attention as a possible method for generating ultrashort pulses. A large number of Raman orders can be generated when the Raman-active medium is pumped by two laser pulses that have a frequency separation equal to the Raman transition frequency. High order Raman generation has been studied in the different temporal regimes, namely: adiabatic, where the pump pulses are much longer than the coherence time of the transition; transient, where the pulse duration is comparable to the coherence time; and impulsive, where the bandwidth of the ultrashort pulse is wider than the transition frequency. To date, almost all of the work has been concerned with generating as broad a spectrum as possible, but we are interested in studying the spectra of the individual orders when pumped in the transient regime. We concentrate on looking at extra peaks that are generated when the Raman medium is pumped with linearly chirped pulses. The extra peaks are generated on the low frequency side of the Raman orders. We discuss how linear Raman scattering from two-photon dressed states can lead to the generation of these extra peaks. Full article

(This article belongs to the Special Issue Multi-Color Laser Emission for the Generation of Ultrashort Optical Pulse)

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371 KiB

Open AccessArticle

Comparisons of Halogenated β-Nitrostyrenes as Antimicrobial Agents

by Hugh Cornell, Thu Nguyen, Gina Nicoletti, Neale Jackson and Helmut Hügel

Appl. Sci. 2014, 4(3), 380-389; https://doi.org/10.3390/app4030380 - 29 Aug 2014

Cited by 16 | Viewed by 7116

Abstract

The influence of three types of halogen-substituted E-β-methyl-β-nitrostyrenes (such as Compounds B, D, H) to overcome bacterial activity that is currently a significant health threat was studied. The evaluations of their bio-potency was measured and related to their structure [...] Read more.

The influence of three types of halogen-substituted E-β-methyl-β-nitrostyrenes (such as Compounds B, D, H) to overcome bacterial activity that is currently a significant health threat was studied. The evaluations of their bio-potency was measured and related to their structure and activity relationships for the purposes of serving to inhibit and overcoming resistant microorganisms. In particular, fluorine-containing β-nitrostyrenes were found to be highly active antimicrobial agents. The addition of the β-bromo group enhanced the antibacterial activity significantly. Our work has illustrated that halogen substituents at both the 4-position in the aromatic ring and also at the β-position on the alkene side chain of nitropropenyl arenes enhanced the antimicrobial activity of these compounds. Full article

(This article belongs to the Special Issue Feature Papers)

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457 KiB

Open AccessArticle

Optimizing Re-planning Operation for Smart House Applying Solar Radiation Forecasting

by Atsushi Yona, Tomonobu Senjyu, Toshihisa Funabashi, Paras Mandal and Chul-Hwan Kim

Appl. Sci. 2014, 4(3), 366-379; https://doi.org/10.3390/app4030366 - 22 Aug 2014

Cited by 5 | Viewed by 6768

Abstract

This paper proposes the re-planning operation method using Tabu Search for direct current (DC) smart house with photovoltaic (PV), solar collector (SC), battery and heat pump system. The proposed method is based on solar radiation forecasting using reported weather data, Fuzzy theory and [...] Read more.

This paper proposes the re-planning operation method using Tabu Search for direct current (DC) smart house with photovoltaic (PV), solar collector (SC), battery and heat pump system. The proposed method is based on solar radiation forecasting using reported weather data, Fuzzy theory and Recurrent Neural Network. Additionally, the re-planning operation method is proposed with consideration of solar radiation forecast error, battery and inverter losses. In this paper, it is assumed that the installation location for DC smart house is Okinawa, which is located in Southwest Japan. The validity of proposed method is confirmed by comparing the simulation results. Full article

(This article belongs to the Special Issue Photovoltaic Generation)

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3296 KiB

Open AccessArticle

Heterospin Junctions in Zigzag-Edged Graphene Nanoribbons

by Eduardo C. Girão, Liangbo Liang and Vincent Meunier

Appl. Sci. 2014, 4(3), 351-365; https://doi.org/10.3390/app4030351 - 18 Aug 2014

Cited by 1 | Viewed by 7302

Abstract

We propose a graphene nanoribbon-based heterojunction, where a defect-free interface separates two zigzag graphene nanoribbons prepared in opposite antiferromagnetic spin configurations. This heterospin junction is found to allow the redirecting of low-energy electrons from one edge to the other. The basic scattering mechanisms [...] Read more.

We propose a graphene nanoribbon-based heterojunction, where a defect-free interface separates two zigzag graphene nanoribbons prepared in opposite antiferromagnetic spin configurations. This heterospin junction is found to allow the redirecting of low-energy electrons from one edge to the other. The basic scattering mechanisms and their relation to the system’s geometry are investigated through a combination of Landauer–Green’s function and the S-matrix and eigen-channel methods within a tight-binding + Hubbard model validated with density functional theory. The findings demonstrate the possibility of using zigzag-edged graphene nanoribbons (zGNRs) in complex networks where current can be transmitted across the entire system, instead of following the shortest paths along connected edges belonging to the same sub-lattice. Full article

(This article belongs to the Special Issue Towards Applications of Graphene)

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2580 KiB

Open AccessArticle

Selection of a Visible-Light vs. Thermal Infrared Sensor in Dynamic Environments Based on Confidence Measures

by Juan Serrano-Cuerda, Antonio Fernández-Caballero and María T. López

Appl. Sci. 2014, 4(3), 331-350; https://doi.org/10.3390/app4030331 - 8 Aug 2014

Cited by 19 | Viewed by 5808

Abstract

This paper introduces a confidence measure scheme in a bimodal camera setup for automatically selecting visible-light or a thermal infrared in response to natural environmental changes. The purpose of the setup is to robustly detect people in dynamic outdoor scenarios under very different [...] Read more.

This paper introduces a confidence measure scheme in a bimodal camera setup for automatically selecting visible-light or a thermal infrared in response to natural environmental changes. The purpose of the setup is to robustly detect people in dynamic outdoor scenarios under very different conditions. For this purpose, two efficient segmentation algorithms, one dedicated to the visible-light spectrum and another one to the thermal infrared spectrum, are implemented. The segmentation algorithms are applied to five different video sequences recorded under very different environmental conditions. The results of the segmentation in both spectra allow one to establish the best-suited confidence interval thresholds and to validate the overall approach. Indeed, the confidence measures take linguistic values LOW, MEDIUM and HIGH, depending on the reliability of the results obtained in visible-light, as well as in thermal infrared video. Full article

(This article belongs to the Special Issue Feature Papers)

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526 KiB

Open AccessArticle

High-Energy, Multicolor Femtosecond Pulses from the Deep Ultraviolet to the Near Infrared Generated in a Hydrogen-Filled Gas Cell and Hollow Fiber

by Kazuya Motoyoshi, Yuichiro Kida and Totaro Imasaka

Appl. Sci. 2014, 4(3), 318-330; https://doi.org/10.3390/app4030318 - 1 Jul 2014

Cited by 10 | Viewed by 6722

Abstract

We investigate four-wave mixing in hydrogen gas using a gas cell and a hollow fiber for the generation of high-energy, multicolor femtosecond (fs) optical pulses. Both a hydrogen-filled gas cell and hollow fiber lead to the generation of multicolor fs pulses in a [...] Read more.

We investigate four-wave mixing in hydrogen gas using a gas cell and a hollow fiber for the generation of high-energy, multicolor femtosecond (fs) optical pulses. Both a hydrogen-filled gas cell and hollow fiber lead to the generation of multicolor fs pulses in a broad spectral range from the deep ultraviolet to the near infrared. However, there is a difference in the energy distribution of the multicolor emission between the gas cell and the hollow fiber. The hydrogen-filled gas cell generates visible pulses with higher energies than the pulses created by the hollow fiber. We have generated visible pulses with energies of several tens of microjoules. The hydrogen-filled hollow fiber, on the other hand, generates ultraviolet pulses with energies of a few microjoules, which are higher than the energies of the ultraviolet pulses generated in the gas cell. In both schemes, the spectral width of each emission line supports a transform-limited pulse duration shorter than 15 fs. Four-wave mixing in hydrogen gas therefore can be used for the development of a light source that emits sub-20 fs multicolor pulses in a wavelength region from the deep ultraviolet to the near infrared with microjoule pulse energies. Full article

(This article belongs to the Special Issue Multi-Color Laser Emission for the Generation of Ultrashort Optical Pulse)

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Appl. Sci., Volume 4, Issue 3 (September 2014) – 9 articles , Pages 318-481

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