Advances in Condensed Matter Physics http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Optical Properties of Sol-Gel Nb2O5 Films with Tunable Porosity for Sensing Applications Mon, 29 Jun 2015 11:42:59 +0000 http://www.hindawi.com/journals/acmp/2015/403196/ Thin Nb2O5 films with tunable porosity are deposited by the sol-gel and evaporation induced self-assembly methods using organic template Pluronic PE6100 with different molar fractions with respect to NbCl5 used as a precursor for synthesis of Nb sol. Surface morphology and structure of the films are studied by Transmission Electron Microscopy and Selected Area Electron Diffraction. The optical characterization of the films is carried out through reflectance spectra measurements of the films deposited on silicon substrates and theoretical modeling in order to obtain refractive index, extinction coefficient, and thickness of the films. The overall porosity of the films and the amount of adsorbed acetone vapors in the pores are quantified by means of Bruggeman effective medium approximation using already determined optical constants. The sensing properties of the samples are studied by measuring both the reflectance spectra and room-temperature photoluminescence spectra prior to and after exposure to acetone vapors and liquid, respectively. The potential of using the studied mesoporous Nb2O5 films for chemooptical sensing is demonstrated and discussed. Rosen Georgiev, Biliana Georgieva, Marina Vasileva, Petar Ivanov, and Tsvetanka Babeva Copyright © 2015 Rosen Georgiev et al. All rights reserved. Characterization of Precipitation in Al-Li Alloy AA2195 by means of Atom Probe Tomography and Transmission Electron Microscopy Mon, 22 Jun 2015 08:41:05 +0000 http://www.hindawi.com/journals/acmp/2015/647468/ The microstructure of the commercial alloy AA2195 was investigated on the nanoscale after conducting T8 tempering. This particular thermomechanical treatment of the specimen resulted in the formation of platelet-shaped precipitates within the Al matrix. The electrochemically prepared samples were analyzed by scanning transmission electron microscopy and atom probe tomography for chemical mapping. The platelets, which are less than 2 nm thick, have the stoichiometric composition consistent with the expected Al2Cu equilibrium composition. Additionally, the Li distribution inside the platelets was found to equal the same value as in the matrix. The equally thin platelet deviates from the formula (Al2CuLi) in its stoichiometry and shows Mg enrichment inside the platelet without any indication of a higher segregation level at the precipitate/matrix interface. The deviation from the (Al2CuLi) stoichiometry cannot be simply interpreted as a consequence of artifacts when measuring the Cu and Li concentrations inside the platelet. The results show rather a strong hint for a true lower Li and Cu contents, hence supporting reasonably the hypothesis that the real chemical composition for the thin platelet in the T8 tempering condition differs from the equilibrium composition of the thermodynamic stable bulk phase. Muna Khushaim, Torben Boll, Judith Seibert, Ferdinand Haider, and Talaat Al-Kassab Copyright © 2015 Muna Khushaim et al. All rights reserved. A Study on the Stoichiometry of One-Dimensional Nanostructures Thu, 18 Jun 2015 11:51:42 +0000 http://www.hindawi.com/journals/acmp/2015/587696/ While attributes such as small dimensions, low power consumption, fast sensor response, and a wide range of detection give one-dimensional nanostructures excellent potential to revolutionize sensor and detector industries, challenges to achieving uniform stoichiometry pose significant obstacles to their commercial use. Diverse characteristics arise from nanostructures with variable compositions and morphologies. Thus, investigation of physical properties of nanostructures would be pointless if one cannot assure the exact stoichiometry of the material. We studied the stoichiometry of ZnTe nanowires grown via the vapor-liquid-solid method. Different microscopy and composition analysis methods were exploited to study the stoichiometry of the nanowires. It was observed that nonstoichiometric wires had relatively higher defect concentrations. The temperature profile along the substrate during nanowire growth was found to be the reason for the formation of nanowires with different stoichiometries. Keivan Davami, Mehrdad Shaygan, Nazli Kheirabi, and Hessam Ghassemi Copyright © 2015 Keivan Davami et al. All rights reserved. The Quantum Well of One-Dimensional Photonic Crystals Thu, 18 Jun 2015 07:58:49 +0000 http://www.hindawi.com/journals/acmp/2015/959546/ We have studied the transmissivity of one-dimensional photonic crystals quantum well (QW) with quantum theory approach. By calculation, we find that there are photon bound states in the QW structure , and the numbers of the bound states are equal to . We have found that there are some new features in the QW, which can be used to design optic amplifier, attenuator, and optic filter of multiple channel. Xiao-Jing Liu, Ji Ma, Xiang-Dong Meng, Hai-Bo Li, Jing-Bin Lu, Hong Li, Wan-Jin Chen, Xiang-Yao Wu, Si-Qi Zhang, and Yi-Heng Wu Copyright © 2015 Xiao-Jing Liu et al. All rights reserved. An Efficient Compact Finite Difference Method for the Solution of the Gross-Pitaevskii Equation Tue, 09 Jun 2015 16:05:58 +0000 http://www.hindawi.com/journals/acmp/2015/127580/ We present an efficient, unconditionally stable, and accurate numerical method for the solution of the Gross-Pitaevskii equation. We begin with an introduction on the gradient flow with discrete normalization (GFDN) for computing stationary states of a nonconvex minimization problem. Then we present a new numerical method, CFDM-AIF method, which combines compact finite difference method (CFDM) in space and array-representation integration factor (AIF) method in time. The key features of our methods are as follows: (i) the fourth-order accuracy in space and rth () accuracy in time which can be achieved and (ii) the significant reduction of storage and CPU cost because of array-representation technique for efficient handling of exponential matrices. The CFDM-AIF method is implemented to investigate the ground and first excited state solutions of the Gross-Pitaevskii equation in two-dimensional (2D) and three-dimensional (3D) Bose-Einstein condensates (BECs). Numerical results are presented to demonstrate the validity, accuracy, and efficiency of the CFDM-AIF method. Rongpei Zhang, Jia Liu, and Guozhong Zhao Copyright © 2015 Rongpei Zhang et al. All rights reserved. Elastic Properties of Liquid Surfaces Coated with Colloidal Particles Sun, 31 May 2015 13:35:55 +0000 http://www.hindawi.com/journals/acmp/2015/206578/ The physical mechanism of elasticity of liquid surfaces coated with colloidal particles is proposed. It is suggested that particles are separated by water clearings and the capillary interaction between them is negligible. The case is treated when the colloidal layer is deformed normally to its surface. The elasticity arises as an interfacial effect. The effective Young modulus of a surface depends on the interfacial tension, equilibrium contact angle, radius of colloidal particles, and their surface density. For the nanometrically scaled particles the line tension becomes essential and has an influence on the effective Young modulus. Edward Bormashenko, Gene Whyman, and Oleg Gendelman Copyright © 2015 Edward Bormashenko et al. All rights reserved. Analytical Model of Subthreshold Drain Current Characteristics of Ballistic Silicon Nanowire Transistors Sun, 31 May 2015 11:58:01 +0000 http://www.hindawi.com/journals/acmp/2015/605987/ A physically based subthreshold current model for silicon nanowire transistors working in the ballistic regime is developed. Based on the electric potential distribution obtained from a 2D Poisson equation and by performing some perturbation approximations for subband energy levels, an analytical model for the subthreshold drain current is obtained. The model is further used for predicting the subthreshold slopes and threshold voltages of the transistors. Our results agree well with TCAD simulation with different geometries and under different biasing conditions. Wanjie Xu, Hei Wong, and Hiroshi Iwai Copyright © 2015 Wanjie Xu et al. All rights reserved. Single Mobile Micro Droplet-Particle Pairs Spatially Captured by Macro Host Droplets on a Superhydrophobic Surface Thu, 28 May 2015 14:12:15 +0000 http://www.hindawi.com/journals/acmp/2015/801547/ In this preliminary study, we demonstrate how small single water droplets can be spatially captured on the surface of individual micron sized hydrophobic coated particles (C18) which adhere to the surface of a nonmobile larger host water droplet resting on a superhydrophobic surface. The formation of the larger droplet, particle adhesion to that droplet, and smaller droplet formation on the particle all take place spontaneously from condensation conditions. These micro droplet-particle pairs are confined to the surface (liquid-air interface) of the larger host droplet; however, they are free to engage with external forces to promote mobility. This response may find applications for particle pair transport on liquid surfaces. We also demonstrate that droplets can be captured or removed from the larger droplet surface via a self-propulsion mechanism. Gregory S. Watson, Bronwen W. Cribb, and Jolanta A. Watson Copyright © 2015 Gregory S. Watson et al. All rights reserved. Effects of the Junction Functionality and Chain Entanglements in Chemomechanical Behavior of Polyelectrolyte Gels Tue, 26 May 2015 09:02:59 +0000 http://www.hindawi.com/journals/acmp/2015/345810/ By considering the functionality of junctions and entanglements of polymer chains for polyelectrolyte gels, a new free energy density function is presented via combining Edwards-Vilgis slip-link model with Flory-Huggins theory. On this basis, the effects of the functionality of network junctions and entanglements of polymer chains are systematically analyzed for free swelling of a cubic polyelectrolyte gel and constrained swelling of a blanket layer of the gel. Analytical results show that the functionality of junctions and chains entanglements plays an important role in the coupled chemomechanical deformation of polyelectrolyte gels. Lianhua Ma, Qingsheng Yang, and Chunhui Yang Copyright © 2015 Lianhua Ma et al. All rights reserved. Structural and Electronic Properties of GaN (0001)/α-Al2O3 (0001) Interface Wed, 20 May 2015 11:34:49 +0000 http://www.hindawi.com/journals/acmp/2015/469487/ Structural and electronic properties of the interface between α-Al2O3 (0001) and GaN (0001) surfaces are investigated through ab initio calculations within the density functional theory. Two different structural models have been investigated interface N(Ga)-terminated. The interface N-terminated GaN surface seems to exhibit the lowest formation energy. The studied interface models are metallic, with the levels at energy spatially confined in the interface region. Our calculations show strong hybridization between atoms in the interface region. M. B. Pereira, E. M. Diniz, and S. Guerini Copyright © 2015 M. B. Pereira et al. All rights reserved. Shape-Dependent Energy of an Elliptical Jellium Background Sun, 17 May 2015 11:33:31 +0000 http://www.hindawi.com/journals/acmp/2015/851356/ The jellium model is commonly used in condensed matter physics to study the properties of a two-dimensional electron gas system. Within this approximation, one assumes that electrons move in the presence of a neutralizing background consisting of uniformly spread positive charge. When properties of bulk systems (of infinite size) are studied, shape of the jellium domain is irrelevant. However, the same cannot be said when one is dealing with finite systems of electrons confined in a finite two-dimensional region of space. In such a case, geometry and shape of the jellium background play a role on the overall properties of the system. In this work, we assume that the region where the electrons are confined is represented by a jellium background charge with an elliptical shape. It is shown that, in this case, the Coulomb self-energy of the elliptically shaped region can be exactly calculated in closed analytical form by using suitable mathematical transformations. The results obtained reveal the external influence of geometry/shape on the properties of two-dimensional systems of few electrons confined to a small finite region of space. Orion Ciftja, LeDarion Escamilla, and Ryan Mills Copyright © 2015 Orion Ciftja et al. All rights reserved. Band Structure Analysis of La0.7Sr0.3MnO3 Perovskite Manganite Using a Synchrotron Thu, 14 May 2015 08:34:54 +0000 http://www.hindawi.com/journals/acmp/2015/746475/ Oxide semiconductors and their application in next-generation devices have received a great deal of attention due to their various optical, electric, and magnetic properties. For various applications, an understanding of these properties and their mechanisms is also very important. Various characteristics of these oxides originate from the band structure. In this study, we introduce a band structure analysis technique using a soft X-ray energy source to study a (LSMO) oxide semiconductor. The band structure is formed by a valence band, conduction band, band gap, work function, and electron affinity. These can be determined from secondary electron cut-off, valence band spectrum, O 1s core electron, and O K-edge measurements using synchrotron radiation. A detailed analysis of the band structure of the LSMO perovskite manganite oxide semiconductor thin film was established using these techniques. Hong-Sub Lee and Hyung-Ho Park Copyright © 2015 Hong-Sub Lee and Hyung-Ho Park. All rights reserved. Influence of Size Effect on the Electronic and Elastic Properties of Graphane Nanoflakes: Quantum Chemical and Empirical Investigations Mon, 04 May 2015 09:34:36 +0000 http://www.hindawi.com/journals/acmp/2015/735192/ By application of empirical method it is found that graphene nanoflake (graphane) saturated by hydrogen is not elastic material. In this case, the modulus of the elastic compression of graphane depends on its size, allowing us to identify the linear parameters of graphane with maximum Young’s modulus for this material. The electronic structure of graphane nanoflakes was calculated by means of the semiempirical tight-binding method. It is found that graphane nanoflakes can be characterized as dielectric. The energy gap of these particles decreases with increasing of the length tending to a certain value. At the same time, the ionization potential of graphane also decreases. A comparative analysis of the calculated values with the same parameters of single-walled nanotubes is performed. A. S. Kolesnikova, M. M. Slepchenkov, M. F. Lin, and O. E. Glukhova Copyright © 2015 A. S. Kolesnikova et al. All rights reserved. Si- and Ge-Based Electronic Devices Mon, 27 Apr 2015 12:44:44 +0000 http://www.hindawi.com/journals/acmp/2015/864972/ Yi Zhao, Rui Zhang, Jiwu Lu, and Wenfeng Zhang Copyright © 2015 Yi Zhao et al. All rights reserved. Characteristics and Breakdown Behaviors of Polysilicon Resistors for High Voltage Applications Mon, 27 Apr 2015 08:09:28 +0000 http://www.hindawi.com/journals/acmp/2015/423074/ With the rapid development of the power integrated circuit technology, polysilicon resistors have been widely used not only in traditional CMOS circuits, but also in the high voltage applications. However, there have been few detailed reports about the polysilicon resistors’ characteristics, like voltage and temperature coefficients and breakdown behaviors which are critical parameters of high voltage applications. In this study, we experimentally find that the resistance of the polysilicon resistor with a relatively low doping concentration shows negative voltage and temperature coefficients, while that of the polysilicon resistor with a high doping concentration has positive voltage and temperature coefficients. Moreover, from the experimental results of breakdown voltages of the polysilicon resistors, it could be deduced that the breakdown of polysilicon resistors is thermally rather than electrically induced. We also proposed to add an N-type well underneath the oxide to increase the breakdown voltage in the vertical direction when the substrate is P-type doped. Xiao-Yu Tang and Ke Dong Copyright © 2015 Xiao-Yu Tang and Ke Dong. All rights reserved. Transformation of Holes Emission Paths under Negative Bias Temperature Stress in Deeply Scaled pMOSFETs Mon, 27 Apr 2015 06:25:24 +0000 http://www.hindawi.com/journals/acmp/2015/508610/ We examine the impact of negative bias temperature (NBT) stress on the fluctuations in and for deeply scaled pMOSFETs and find that the relative high NBT stress triggers -RTN and -step. Through the analysis of the field dependence of emission constant and the carrier separation measurement, it is found that under the relative high NBT stress some traps keep charged state for very long time, as observing step-like behaviors in , while other traps emit charged holes to the gate side through TAT process, which originate both -step and ID-RTN. Yiming Liao, Xiaoli Ji, Qiang Guo, and Feng Yan Copyright © 2015 Yiming Liao et al. All rights reserved. DC Characteristics Optimization of a Double G-Shield 50 V RF LDMOS Thu, 23 Apr 2015 14:02:39 +0000 http://www.hindawi.com/journals/acmp/2015/379746/ An N-type 50 V RF LDMOS with a RESURF (reduced surface field) structure of dual field plates (grounded shield, or G-shield) was investigated. The effect of the two field plates and N-drift region, including the junction depth and dopant concentration, on the DC characteristics was analyzed by employing the Taurus TCAD device simulator. A high BV (breakdown voltage) can be achieved while keeping a low (on-resistance). The simulation results show that the N-drift region dopant concentration has an obvious effect on the BV and and the junction depth affected these values less. There is an optimized length for the second field plate for a given dopant concentration of the N-drift region. Both factors should be optimized together to determine the best DC characteristics. Meanwhile, the effect of the first field plate on the BV and can be ignored. According to the simulation results, 50 V RF LDMOS with an optimized RESURF structure of a double G-shield was fabricated using 0.35 µm technologies. The measurement data show the same trend as the TCAD simulation, where a BV of 118 V and of 26 ohm·mm were achieved. Xiangming Xu, Pengliang Ci, Xiaoyu Tang, Jing Shi, Zhengliang Zhou, Jingfeng Huang, Peng-Fei Wang, and David Wei Zhang Copyright © 2015 Xiangming Xu et al. All rights reserved. Design of a Novel W-Sinker RF LDMOS Thu, 23 Apr 2015 13:19:49 +0000 http://www.hindawi.com/journals/acmp/2015/312646/ A novel RF LDMOS device structure and corresponding manufacturing process are presented in this paper. Deep trench W-sinker (tungsten sinker) is employed in this technology to replace the traditional heavily doped diffusion sinker which can shrink chip size of the LDMOS transistor by more than 30% and improve power density. Furthermore, the W-sinker structure reduces the parasitic resistance and inductance and improves thermal conductivity of the device as well. Combined with the adoption of the techniques, like grounded shield, step gate oxide, LDD optimization, and so forth, an advanced technology for RF LDMOS based on conventional 0.35 m CMOS technology is well established. An power amplifier product with frequency range of 1.8–2.1 GHz is developed for the application of 4G LTE base station and industry leading performance is achieved. The qualification results show that the device reliability and ruggedness can also meet requirement of the application. Xiangming Xu, Han Yu, Jingfeng Huang, Chun Wang, Wei Ji, Zhengliang Zhou, Ying Cai, Yong Wang, Pingliang Li, Peng-Fei Wang, and David Wei Zhang Copyright © 2015 Xiangming Xu et al. All rights reserved. High-Electron-Mobility SiGe on Sapphire Substrate for Fast Chipsets Thu, 23 Apr 2015 12:46:10 +0000 http://www.hindawi.com/journals/acmp/2015/785415/ High-quality strain-relaxed SiGe films with a low twin defect density, high electron mobility, and smooth surface are critical for device fabrication to achieve designed performance. The mobilities of SiGe can be a few times higher than those of silicon due to the content of high carrier mobilities of germanium (p-type Si: 430 cm2/V·s, p-type Ge: 2200 cm2/V·s, n-type Si: 1300 cm2/V·s, and n-type Ge: 3000 cm2/V·s at 1016 per cm3 doping density). Therefore, radio frequency devices which are made with rhombohedral SiGe on -plane sapphire can potentially run a few times faster than RF devices on SOS wafers. NASA Langley has successfully grown highly ordered single crystal rhombohedral epitaxy using an atomic alignment of the direction of cubic SiGe on top of the direction of the sapphire basal plane. Several samples of rhombohedrally grown SiGe on -plane sapphire show high percentage of a single crystalline over 95% to 99.5%. The electron mobilities of the tested samples are between those of single crystals Si and Ge. The measured electron mobility of 95% single crystal SiGe was 1538 cm2/V·s which is between 350 cm2/V·s (Si) and 1550 cm2/V·s (Ge) at 6 × 1017/cm3 doping concentration. Hyun Jung Kim, Yeonjoon Park, Hyung Bin Bae, and Sang H. Choi Copyright © 2015 Hyun Jung Kim et al. All rights reserved. Responsivity Enhanced NMOSFET Photodetector Fabricated by Standard CMOS Technology Thu, 23 Apr 2015 12:41:33 +0000 http://www.hindawi.com/journals/acmp/2015/639769/ Increasing the responsivity is one of the important issues for a photodetector. In this paper, we demonstrate an improved NMOSFET photodetector by using deep-n-well (DNW) structure which can improve the responsivity of the photodetector significantly. The experimental results show that the responsivity can be enhanced greatly by the DNW structure and is much larger than the previous work when DNW is biased with 0.5 V, while the dark current exhibits almost no increase. Further characterization indicates that the diode formed by the bulk and DNW can efficiently absorb photons and has a large gain factor of the photocurrent especially under low light condition, which gives a more promising application for the detector to detect the weak light. Fuwei Wu, Xiaoli Ji, and Feng Yan Copyright © 2015 Fuwei Wu et al. All rights reserved. The Investigation of Field Plate Design in 500 V High Voltage NLDMOS Thu, 23 Apr 2015 12:38:40 +0000 http://www.hindawi.com/journals/acmp/2015/834545/ This paper presents a 500 V high voltage NLDMOS with breakdown voltage () improved by field plate technology. Effect of metal field plate (MFP) and polysilicon field plate (PFP) on breakdown voltage improvement of high voltage NLDMOS is studied. The coeffect of MFP and PFP on drain side has also been investigated. A 500 V NLDMOS is demonstrated with a 37 μm drift length and optimized MFP and PFP design. Finally the breakdown voltage 590 V and excellent on-resistance performance ( = 7.88 ohm * mm2) are achieved. Donghua Liu, Xiangming Xu, Feng Jin, Wenting Duan, Huihui Wang, Jing Shi, Yuan Yao, Jun Hu, Wensheng Qian, Pengfei Wang, and David Wei Zhang Copyright © 2015 Donghua Liu et al. All rights reserved. Interface Engineering and Gate Dielectric Engineering for High Performance Ge MOSFETs Thu, 23 Apr 2015 12:24:09 +0000 http://www.hindawi.com/journals/acmp/2015/639218/ In recent years, germanium has attracted intensive interests for its promising applications in the microelectronics industry. However, to achieve high performance Ge channel devices, several critical issues still have to be addressed. Amongst them, a high quality gate stack, that is, a low defect interface layer and a dielectric layer, is of crucial importance. In this work, we first review the existing methods of interface engineering and gate dielectric engineering and then in more detail we discuss and compare three promising approaches (i.e., plasma postoxidation, high pressure oxidation, and ozone postoxidation). It has been confirmed that these approaches all can significantly improve the overall performance of the metal-oxide-semiconductor field effect transistor (MOSFET) device. Jiabao Sun and Jiwu Lu Copyright © 2015 Jiabao Sun and Jiwu Lu. All rights reserved. Ozone Treatment Improved the Resistive Switching Uniformity of HfAlO2 Based RRAM Devices Thu, 23 Apr 2015 11:55:12 +0000 http://www.hindawi.com/journals/acmp/2015/714097/ HfAlO2 based resistive random access memory (RRAM) devices were fabricated using atomic layer deposition by modulating deposition cycles for HfO2 and Al2O3. Effect of ozone treatment on the resistive switching uniformity of HfAlO2 based RRAM devices was investigated. Compared to the as-fabricated devices, the resistive switching uniformity of HfAlO2 based RRAM devices with the ozone treatment is significantly improved. The uniformity improvement of HfAlO2 based RRAM devices is related to changes in compositional and structural properties of the HfAlO2 resistive switching film with the ozone treatment. Lifeng Liu, Yi Hou, Weibing Zhang, Dedong Han, and Yi Wang Copyright © 2015 Lifeng Liu et al. All rights reserved. Retracted: Quadrupole Excitation in Tunnel Splitting Oscillation in Nanoparticle Mn12 Thu, 16 Apr 2015 07:34:27 +0000 http://www.hindawi.com/journals/acmp/2015/191840/ Advances in Condensed Matter Physics Copyright © 2015 Advances in Condensed Matter Physics. All rights reserved. Chemical Reduction of Nd1.85Ce0.15CuO4−δ Powders in Supercritical Sodium Ammonia Solutions Wed, 08 Apr 2015 13:10:58 +0000 http://www.hindawi.com/journals/acmp/2015/873972/ Nd1.85Ce0.15CuO4−δ powders are chemically reduced in supercritical sodium ammonia solutions from room temperature to 350°C. The crystallographic structure of the reduced powders is investigated from Rietveld refinement of X-ray powder diffraction. The atomic positions are maintained constant within experimental errors while temperature factors of all atoms increase significantly after the chemical treatments, especially of Nd/Ce atoms. The ammonothermally reduced Nd1.85Ce0.15CuO4−δ powders show diamagnetic below 24 K which is contributed to the lower oxygen content and higher temperature factors of atoms in the treated compound. The ammonothermal method paves a new way to reduce oxides in supercritical solutions near room temperature. Yasmin Dias, Hui Wang, Haiqing Zhou, Feng Lin, and Yucheng Lan Copyright © 2015 Yasmin Dias et al. All rights reserved. A Generalization of Electromagnetic Fluctuation-Induced Casimir Energy Wed, 25 Mar 2015 12:48:31 +0000 http://www.hindawi.com/journals/acmp/2015/198657/ Intermolecular forces responsible for adhesion and cohesion can be classified according to their origins; interactions between charges, ions, random dipole—random dipole (Keesom), random dipole—induced dipole (Debye) are due to electrostatic effects; covalent bonding, London dispersion forces between fluctuating dipoles, and Lewis acid-base interactions are due to quantum mechanical effects; pressure and osmotic forces are of entropic origin. Of all these interactions, the London dispersion interaction is universal and exists between all types of atoms as well as macroscopic objects. The dispersion force between macroscopic objects is called Casimir/van der Waals force. It results from alteration of the quantum and thermal fluctuations of the electrodynamic field due to the presence of interfaces and plays a significant role in the interaction between macroscopic objects at micrometer and nanometer length scales. This paper discusses how fluctuational electrodynamics can be used to determine the Casimir energy/pressure between planar multilayer objects. Though it is confirmation of the famous work of Dzyaloshinskii, Lifshitz, and Pitaevskii (DLP), we have solved the problem without having to use methods from quantum field theory that DLP resorted to. Because of this new approach, we have been able to clarify the contributions of propagating and evanescent waves to Casimir energy/pressure in dissipative media. Yi Zheng Copyright © 2015 Yi Zheng. All rights reserved. Quadrupole Excitations in Magnetic Susceptibility of Magnetic Nanoparticle Fe8 Tue, 24 Mar 2015 13:52:22 +0000 http://www.hindawi.com/journals/acmp/2015/854625/ Magnetic susceptibility dependence on temperatures in different magnetic fields will be discussed. Until today, to calculate magnetization and magnetic susceptibility, only dipole excitations have been considered, but, due to the symmetry of operators in Hamiltonian and also to achieve more accuracy, other multiple excitations must be taken into account too. To this end, here, both dipole and quadruple excitations are considered and then the resulting curves will be plotted in presence of different magnetic fields. Finally, seen that the graphs obtained using the multipole excitations more accurately with results taken by experimental data. Yousef Yousefi Copyright © 2015 Yousef Yousefi. All rights reserved. Low-Dimensional Semiconductor Structures for Optoelectronic Applications Tue, 24 Mar 2015 09:20:40 +0000 http://www.hindawi.com/journals/acmp/2015/156196/ Wei Lu, Hong Chen, Weida Hu, Guofeng Song, Wen Lei, and Ying Fu Copyright © 2015 Wei Lu et al. All rights reserved. Rebirth of Liquid Crystals for Sensoric Applications: Environmental and Gas Sensors Mon, 23 Mar 2015 08:39:27 +0000 http://www.hindawi.com/journals/acmp/2015/729186/ Films and droplets of liquid crystals may soon become an essential part of sensitive environmental sensors and detectors of volatile organic compounds (VOCs) in the air. In this paper a short overview of recent progress in the area of sensors based on liquid crystals is presented, along with the studies of low molar mass liquid crystals as gas sensors. The detection of VOCs in the air may rely on each of the following effects sequentially observed one after the other: (i) slight changes in orientation and order parameter of liquid crystal, (ii) formation of bubbles on the top of the liquid crystalline droplet, and (iii) complete isotropisation of the liquid crystal. These three stages can be easily monitored by a photo camera and/or optical microscopy. Detection limits corresponding to the first stage are typically lower by a factor of at least 3–6 than detection limits corresponding to isotropisation. The qualitative model taking into account the reorientation of liquid crystals is presented to account for the observed changes. P. V. Shibaev, M. Wenzlick, J. Murray, A. Tantillo, and J. Howard-Jennings Copyright © 2015 P. V. Shibaev et al. All rights reserved. Tuning Rheological Performance of Silica Concentrated Shear Thickening Fluid by Using Graphene Oxide Mon, 23 Mar 2015 08:39:14 +0000 http://www.hindawi.com/journals/acmp/2015/734250/ The addition of a small amount of graphene oxide into a traditional colloidal silica-based shear thickening fluid (STF) can lead to a significant change in viscosity, critical shear rate, storage modulus, and loss modulus of STF. This finding provides an effective way to prepare stronger and light-weight STFs. Wenchao Huang, Yanzhe Wu, Ling Qiu, Cunku Dong, Jie Ding, and Dan Li Copyright © 2015 Wenchao Huang et al. All rights reserved.