Tool For Tuning Research Articles

Osscilating Binding Energy of a Donor Impurity Confined within CdS-Sio2 Constant Total Effective Radius Multi-Shells Quantum Dots

In this paper, we have studied the effect of a number of wells and quantum dot thickness on binding energy of a single donor impurity confined within a CdS-SiO2 constant total effective radius multi-shells quantum dot (CTER-MSQD) system. We have shown that impurity binding energy versus number of wells in a quantum dot with fixed outer radius oscillates when amplitude increases. By using well number variation, adding impurity and changing quantum dot radius as three tuning tools, localization of wave-functions in each part of the quantum dot along the radius has been now made possible. Finally, adding the impurity leads to more probability of finding the electrons in the wells near the center of the quantum dot.

UV Direct Laser Interference Patterning of polyurethane substrates as tool for tuning its surface wettability

Direct Laser Interference Patterning (DLIP) is a versatile tool for the fabrication of micro and sub-micropatterns on different materials. In this work, DLIP was used to produce periodic surface structures on polyurethane (PU) substrates with spatial periods ranging from 0.5 to 5.0μm. The influence of the laser energy density on the quality and topographical characteristics of the produced micropatterns was investigated. To characterize the surface topography of the produced structures, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Confocal Microscopy (CFM) were utilized. It was found that high quality and defect free periodic line-like patterns with spatial periods down to 500nm could be fabricated, with structure depths between 0.88 up to 1.25μm for spatial periods larger than 2.0μm and up to 270nm for spatial periods between 500nm and 1.0μm. Measurements of the contact angle of water on the treated surface allowed to identify an anisotropic wetting behavior depending mainly on the spatial period and filling factor of the structured surfaces.

Tuning the plasmonic response of bimetallic films by laser irradiation

Abstract This work shows that surface treatment of multilayer Au and Ag thin films with single UV nanosecond laser pulses is a versatile and an easy-to-use tool for tuning their optical response or colour in a wide spectral range. As a laser parameter, we have varied the fluence. As film parameters, we have studied the film configuration by changing the deposition order, number of layers as well as the composition by varying the thickness of the Au layer while keeping that of Ag constant. The laser exposure produces melting of the layers followed by mixing of the two metals and dewetting, which lead to nanoparticle (NP) formation. The optical response is dominated by the surface plasmon resonance (SPR) associated to the NPs whose wavelength, intensity and bandwidth are consistent with the observed NP morphologies, the number density and the variation of optical constants with Au content. It is dominated by the balance between the interband transition onset of the alloy and the SPR of the nanoalloyed NPs for low fluences and by multipolar interactions for high fluences. While the Au content allows tuning the SPR in the range of ≈ 180 nm, the laser fluence allows a fine tuning of the SPR features and the film configuration has little impact on the optical response. All together this allows tuning the colour in ranges broader than 20 CIELAB units along the two chromatic axes.

Effects of hydrogen adsorption on the properties of double wall BN and (BN)xCy nanotubes

In the present contribution, we apply first-principles calculations, based on the density functional theory, to study the effects of hydrogen adsorption on the structural and electronic properties of boron nitride and hybrid carbon–boron nitride double wall nanotubes. The results demonstrate that the hydrogen decoration induces significant structural deformation and an appreciable reduction in the gap energy. When the number of hydrogen atoms introduced on the outer wall is increased, desorption of hydrogen pairs are observed. The calculations indicate that each adsorbed hydrogen atom induces a structural deformation with an energetic cost of about 68meV/atom. It is also found that the introduction of hydrogen atoms can be applied as an efficient tool for tuning the electronic properties of such structures.

Plasma Nanotextured Polymeric Surfaces for Controlling Cell Attachment and Proliferation: A Short Review

Plasma etching has evolved in an important technology for rapid and cost-effective generation of random or quasi-ordered nanostructures in large areas and in a repeatable manner, if properly controlled. It simultaneously affects the chemical composition of etched surfaces. Thus, plasma etching finds numerous applications in the areas of biomaterials and biomicrosystems, since surface chemistry and topography are proven to influence strongly cell–substrate interactions. Herein, we briefly review published studies addressing cell–surface interactions, especially those focusing on optimal surface properties favoring cell adhesion and proliferation. We show that plasma-based micro- and nano-texturing of polymeric surfaces provides a unique, simple and yet versatile tool for tuning the physicochemical properties of polymeric surfaces to those favoring cell cultures. Plasma etching and nanotexturing is proven indispensable also for the patterning on the same substrate of different chemical and/or topographical areas to induce preferential cell adhesion in predefined areas. In this respect, the implementation of surfaces with extreme wettabilities (superhydrophobic/superhydrophilic patterns) is highly valued and when integrated inside microchannels can add new potential to the current archery of microanalytical devices. The paper concludes with the authors’ view to the future outlook of the niche area of plasma nanotextured polymer surfaces.

The positive piezoconductive effect in graphene.

As the thinnest conductive and elastic material, graphene is expected to play a crucial role in post-Moore era. Besides applications on electronic devices, graphene has shown great potential for nano-electromechanical systems. While interlayer interactions play a key role in modifying the electronic structures of layered materials, no attention has been given to their impact on electromechanical properties. Here we report the positive piezoconductive effect observed in suspended bi- and multi-layer graphene. The effect is highly layer number dependent and shows the most pronounced response for tri-layer graphene. The effect, and its dependence on the layer number, can be understood as resulting from the strain-induced competition between interlayer coupling and intralayer transport, as confirmed by the numerical calculations based on the non-equilibrium Green's function method. Our results enrich the understanding of graphene and point to layer number as a powerful tool for tuning the electromechanical properties of graphene for future applications.

On probabilistic certification of combined cancer therapies using strongly uncertain models

This paper proposes a general framework for probabilistic certification of cancer therapies. The certification is defined in terms of two key issues which are the tumor contraction and the lower admissible bound on the circulating lymphocytes which is viewed as indicator of the patient health. The certification is viewed as the ability to guarantee with a predefined high probability the success of the therapy over a finite horizon despite of the unavoidable high uncertainties affecting the dynamic model that is used to compute the optimal scheduling of drugs injection. The certification paradigm can be viewed as a tool for tuning the treatment parameters and protocols as well as for getting a rational use of limited or expensive drugs. The proposed framework is illustrated using the specific problem of combined immunotherapy/chemotherapy of cancer.

Influence of electric field on separation and orientation of carbon nanotubes in spray coated layers

Purpose – The aims of this paper are to investigate the influence of direct current (DC) electric field on separation and orientation of carbon nanotubes (CNTs) in spray-coated layers and apply this method to the fabrication of elastic and transparent electrodes. The orientation of CNTs in the form of paths in the direction of electrical conduction should increase the electrode conductivity without decreasing its optical transmission. Design/methodology/approach – Materials are deposited using vacuum-free, ultra-fine nozzle spray coating technique, easily applicable for large-scale production. After the deposition of carbon nanomaterials, nanoparticles are oriented in the electric field and initially cured with infrared halogen lamp to evaporate solvents and preserve orientation of the nanoparticles in the deposited layer. Afterwards, layers are cured in a chamber dryer to obtain desired properties. Nanoparticles orientation and carbon nanomaterials separation via DC electric field are analysed, and the optical and electrical properties of prepared electrodes are measured. Findings – Experiments described in this paper showed that DC electric field can be applied provide separation and orientation of CNTs and combined with spray coating technique, can be used as additional tool for tuning the conductivity of flexible and transparent electrodes by decreasing the sheet resistance about five times. Originality/value – The results showed that spray coating combined with electric field orientation is a promising solution of obtaining elastic and transparent electrodes with oriented carbon particles. According to the authors’ knowledge, none of the experiments was directed to obtain DC electric field-oriented transparent layers produced with the use of spray coating technique.

Abstract 240: Strategic Distribution of the Mitochondrial Ca2+ Uniporter in Cardiac Mitochondria

Propagation of SR-derived Ca2+ signals to the mitochondrial matrix is an important tuning tool of cardiac energy metabolism (excitation-bioenergetics coupling). Effective activation of the low-affinity mitochondrial Ca2+ uniporter (mtCU) is supported by high [Ca2+] nanodomains where SR cisternae are tethered to mitochondria. Cardiac mitochondria have large inner membrane (IMM) surface with extensive cristae folding. However, recent comparative patch clamp studies found cardiac mtCU current density extremely low. We hypothesized that efficient excitation-bioenergetics coupling would require strategic positioning of the mtCU. We thus analyzed the distribution of mtCU’s pore protein, MCU in rat and mouse cardiomyocytes and cardiac membrane fractions. Immunofluorescence (IF) using the commercial Sigma antibody showed significant non-mitochondrial (nuclear, cyto/sarcoplasmic) crossreactions as verified in MCU-KO MEFs and cardiomyocytes. To isolate mitochondrial labeling, we performed IF of isolated mitochondria (mtIF) and immunogold electron microscopy of freshly isolated cardiomyocytes. mtIF showed ~50% of MCU-positive structures colocalized with RyR2, in line with a location preference to SR-mitochondria associations. This distribution bias was also reflected in the immunogold TEM analysis. Moreover, WB showed both MCU and calsequestrin being enriched in the same sub-mitochondrial membrane fraction separated on sucrose gradient. The prevalence of MCU and even more the essential MCU regulator (EMRE) was higher in the mitochondria “contaminating” the heavy SR (SR-associated mito membranes) than in the crude mitochondrial fraction. [Ca2+] activation of mitochondrial Ca2+ uptake at similar IMM potentials was as effective in suspensions of SR-associated mito membranes as in the crude mitochondrial fraction. Collectively, our data suggest a location bias of the functionally mandatory mtCU channel components MCU and EMRE toward SR-mitochondrial associations. As the bias is much stronger for EMRE, the component that is required for MCU to function as a channel, it raises the possibility that EMRE availability may be a physiological limiting factor in regional mtCU activity in the cardiac muscle mitochondria.

Electronic doping and redox-potential tuning in colloidal semiconductor nanocrystals.

Electronic doping is one of the most important experimental capabilities in all of semiconductor research and technology. Through electronic doping, insulating materials can be made conductive, opening doors to the formation of p-n junctions and other workhorses of modern semiconductor electronics. Recent interest in exploiting the unique physical and photophysical properties of colloidal semiconductor nanocrystals for revolutionary new device technologies has stimulated efforts to prepare electronically doped colloidal semiconductor nanocrystals with the same control as available in the corresponding bulk materials. Despite the impact that success in this endeavor would have, the development of general and reliable methods for electronic doping of colloidal semiconductor nanocrystals remains a long-standing challenge. In this Account, we review recent progress in the development and characterization of electronically doped colloidal semiconductor nanocrystals. Several successful methods for introducing excess band-like charge carriers are illustrated and discussed, including photodoping, outer-sphere electron transfer, defect doping, and electrochemical oxidation or reduction. A distinction is made between methods that yield excess band-like carriers at thermal equilibrium and those that inject excess charge carriers under thermal nonequilibrium conditions (steady state). Spectroscopic signatures of such excess carriers, accessible by both equilibrium and nonequilibrium methods, are reviewed and illustrated. A distinction is also proposed between the phenomena of electronic doping and redox-potential shifting. Electronically doped semiconductor nanocrystals possess excess band-like charge carriers at thermal equilibrium, whereas redox-potential shifting affects the potentials at which charge carriers are injected under nonequilibrium conditions, without necessarily introducing band-like charge carriers at equilibrium. Detection of the key spectroscopic signatures of band-like carriers allows distinction between these two regimes. Both electronic doping and redox-potential shifting can be powerful tools for tuning the performance of nanocrystals in electronic devices. Finally, key chemical challenges associated with nanocrystal electronic doping are briefly discussed. These challenges are centered largely on the availability of charge-carrier reservoirs with suitable redox potentials and on the relatively poor control over nanocrystal surface traps. In most cases, the Fermi levels of colloidal nanocrystals are defined by the redox properties of their surface traps. Control over nanocrystal surface chemistries is therefore essential to the development of general and reliable strategies for electronically doping colloidal semiconductor nanocrystals. Overall, recent progress in this area portends exciting future advances in controlling nanocrystal compositions, surface chemistries, redox potentials, and charge states to yield new classes of electronic nanomaterials with attractive physical properties and the potential to stimulate unprecedented new semiconductor technologies.

ENG-cladded metamaterial-loaded helical waveguide for optoelectronics applications

In this article, we have studied propagation characteristics of ENG-cladded metamaterial-loaded helical waveguide (CMLHG) to control its slow-wave behaviour for various engineering applications such as realizing optical buffer and memory. An analytical equation has been derived and computed numerically to analyse its dispersion characteristics in THz frequency spectrum. Significant amount of phase velocity reduction is achieved in comparison with the helical guide when (i) it is in free space and not cladded and (ii) when it is cladded with doubly positive materials and loaded with metamaterial. We find that helical waveguide physical dimensions, mainly radius and pitch angle, act as a tuning tool to control the phase velocity. This type of waveguide does not require any active waveguide compensation in order to achieve slow wave at THz to optical frequency range. The electric field intensity distribution over the cross section of the waveguide has also been studied which attributes that as frequency increases, electric field distribution is more confined to the core region of the waveguide.

Optical properties of a multibarrier structure under intense laser fields

Using the diagonalization method and within the effective mass and parabolic band approximations, the energy spectrum and the wave functions are investigated in biased multibarrier structure taking into account the effects of nonresonant intense laser fields. We calculated the optical properties from the susceptibility using a nonperturbative formalism recently reported. We study the changes in the intersubband optical absorption coefficients and refraction index for several values of the dressing laser parameter and for some specific values of the electric field applied along the growth direction of the heterostructure. It is concluded from our study that the peaks in the optical absorption spectrum have redshifts or blueshifts as a function of the laser parameter and the electric field. These parameters could be suitable tools for tuning the electronic and optical properties of the multibarrier structure.

Tuning the crystalline and mesophase structure of olefin block copolymer through self-nucleation and annealing treatments.

As a type of novel semi-crystalline block copolymers, the final properties of olefin block copolymers (OBCs) greatly depend on the crystalline and phase-separated structures. In the present work, we systematically investigated the influence of self-nucleation and annealing on the lamellar and mesophase-separated structure of OBCs. According to the crystalline and melting behavior after self-nucleation and annealing treatments, four different regimes can be recognized with the self-seeding temperature Ts varying from 125 to 109 °C. In regime A, only self-nucleation occurs, while it coexists with lamellar thickening in regime B. In regime C, there is only lamellar thickening behavior. The lamellar thickening induced inconsecutive lamellar crystals observed revealed that the rearrangement of the hard blocks, which are next to the soft blocks and trapped in the intermediate regime between crystalline and amorphous phases, into neighboring lamellar crystals should be the mechanism for the lamellar thickening of the OBCs. Surprisingly, no lamellar thickening occurs and a new small melting peak appears at lower temperatures in regime D. Considering the block dispersity of OBCs, the emergence of a small melting peak at lower temperatures can be attributed to the crystallization of the ethylene sequence with relatively weaker crystallization abilities, which are not able to crystallize in a standard crystalline state. Based on these findings, we gained some new understandings on lamellar thickening behavior of OBCs and established the self-nucleation and annealing process as a powerful tool for tuning the crystalline and phase-separated structures of OBCs.

MicroRNAs and Colorectal Cancer.

Colorectal cancer (CRC) is one of the most common types of human cancer with high cancer-related morbidity and mortality rates. The development and clinical validation of novel therapeutic avenues have improved the clinical outcome, but metastatic CRC still remains an incurable disease in most cases. The interest in discovering novel pathophysiological drivers in CRC is intensively ongoing and the search for novel biomarkers for early diagnosis, for patient's stratification for prognostic purposes or for predicting treatment response are warranted. microRNAs are small RNA molecules that regulate the expression of larger messenger RNA species by different mechanisms with the final consequence to provide a fine tuning tool for global gene expression patterns. First discovered in worms, around 15 years ago it became clear that microRNAs are also existing in humans and that they are widely involved in human carcinogenesis. Within the last years, tremendous progress in the understanding of microRNAs and their role in CRC carcinogenesis has been developed. In this book chapter, several examples of previously identified microRNAs and how they influence colorectal carcinogenesis will be discussed. The information starting at the underlying molecular mechanisms towards clinical applications will be depicted and an overview what great potential these small molecules might carry in future colorectal cancer medicine, will be discussed.

An Experimental Study of Parameter Selection in Particle Swarm Optimization Using an Automated Methodology

In this work, an experimental study to evaluate the parame- ter vector utility brought by an automated tuning tool, so called Hybrid Automatized Tuning procedure (HATp) is given. The experimental work uses the inertia weight and number of iterations from the algorithm PSO; it compares those parameters from tuning by analogy and empirical studies. The task of PSO is to select users to exploit concurrently a channel as long as they achieve the Signal-to-Interference-Ratio (SINR) constraints to maximize throughput; however, as the number of users increases the interference also arises; making more challenging for PSO to converge or to nd a solution. Results show that, HATp is not only able to provide a parameter vector that improve the search ability of PSO to nd a solution but also to enhance its performance on resolving the spectrum sharing application problem than those parameters values suggested by empirical and analogical methodologies in the literature on some problem instances.

Refractive index changes in constant total effective length GaN/AlN multiple quantum well systems under external electric field

In this work we have investigated the effect of external electric field on the electronic structure and refractive index changes of a GaN/AlN constant total effective length multiple quantum well. A decreasing oscillatory behavior for energy levels was seen when the electric field increased and in some energy values the energy levels intersected. By increasing the number of wells, oscillator strength dropped suddenly and moved to higher electric field in a critical electric field. By using the number of wells and the total length of the structure as two tuning tools, we were able to select our previously determined critical electric field.

Simulation of Fractional-Order Low-Pass Filters

The attenuation of standard analog low-pass filters corresponds to a multiple value of -6 decibels per octave. This quantified value is related to the order of the filter. The issue addressed here is concerned with the extension of integer orders to non integer orders, such that the attenuation of a low-pass filter can be continuously adjusted. Fractional differential systems are known to provide such asymptotic behaviors and many results about their simulation are available. But even for a fixed cutoff frequency, their combination does not generate an additive group with respect to the order and they involve stability problems. In this paper, a class of low-pass filters with orders between 0 (the filter is a unit gain) and 1 (standard one-pole filter) is defined to restore these properties. These infinite dimensional filters are not fractional differential but admit some well-posed representations into weighted integrals of standard one-pole filters. Based on this, finite dimensional approximations are proposed and recast into the framework of statespace representations-space representations. A special care is given to reduce the computational complexity, through the dimension of the state. In practice, this objective is reached for the complete family, without damaging the perceptive quality, with dimension 13. Then, an accurate low-cost digital version of this family is built in the time-domain. The accuracy of the digital filters is verified on the complete range of parameters (cutoff frequencies and fractional orders). Moreover, the stability is guaranteed, even for time-varying parameters. As an application, a plugin has been implemented which provides a new audio tool for tuning the cutoff frequency and the asymptotic slope in a continuous way. As a very special application, choosing a one-half order combined with a low cutoff frequency (20 Hz or less), the filter fed with a white noise provides a pink noise generator.

GaN/AlN constant total effective radius multi-wells quantum rings: Physical properties under well number variation effects

In this study, effect of the number of wells and quantum ring thickness on subband electronic structure, ground state wave function, Fermi energy and linear refractive index changes of an AlN/GaN constant total effective radius multi-wells quantum ring have been studied. It is shown that, effect of increasing of the inner quantum ring radius R0 on the ground state energy and other physical properties are larger than increasing of the number of wells. This fact helps the simplification of the experiments, since making quantum ring with larger R0 is easier than making multiple-wells quantum rings. However, effect of the increasing of the R0 values in systems with larger number of wells is also larger. Increase of the R0 also leads to increase of the refractive index changes amplitudes. Resonant energy undergo a red-shift by going from single quantum well system to double quantum well system, and further increasing of the numbers of wells leads to a blue-shift. Finally, we propose number of wells as a tuning tool to select the position of the maximum probability of finding free carriers within the system.

Prediction of coke oven wall pressure

Internal gas pressure (IGP) developed by coking coals upon carbonisation accounts for oven wall pressure (OWP). If not controlled, this OWP may be potentially dangerous as it can easily exceed the 10kPa acceptable limit. In this work, a simple, physically based, expression of IGP in a slot-type coke oven is presented, validated on data available in literature and modified into a ready-to-use expression of OWP fitted on measurements from the movable wall pilot oven of the Centre de Pyrolyse de Marienau (CPM) over a wide range of single coals. Expressed as a function of coal characteristics and carbonisation conditions, this OWP prediction is accurate enough to serve as a process tuning tool. However, probably because additivity rule does not apply easily to inert content, the model fails to predict OWP in case of blends. Extrapolation from the pilot oven to the industrial oven has been proved.

Analisis Alat Bantu Tuning Fisikal Basis Data pada Sql Server 2008

Nowadays every company has been faced with a business competition that requires the company to survive and be superior to its competitors. One strategy used by many companies is to use information technology to run their business processes. The use of information technology would require a storage which commonly referred to as a database to store and process data into useful information for the company. However, it was found that the greater the amount of data in the database, then the speed of the resulting process will decrease because the time needed to access the data will be much longer. The long process of data can cause a decrease in the company’s performance and the length of time needed to make decisions so that this can be a challenge to achieve the company’s competitive advantage. In this study performed an analysis of technique to improve the performance of the database system used by the company to perform tuning on SQL Server 2008 database physically. The purpose of this study is to improve the performance of the database used by speeding up the time it takes when doing query processing. The research methodology used was the method of analysis such as literature studies, analysis of the process and the workings of tuning tools that already exist in SQL Server 2008, and evaluation of applications that have been created, and also tuning methods that include query optimization and create index. The results obtained from this study is an evaluation of the physical application tuning tools that can integrate database functionality of other tuning tools such as SQL Profiler and Database Tuning Advisor.