bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of the Doping Level at Boron Doped Nanocrystalline Diamond Films in the Electrochemical Determination of Nitrite
Authors: Matsushima Jorge T. , Souza Diego H.L. , Souza Fernando A. , Azevedo Adriana F. , Baldan Mauricio R. , Ferreira Neidenei G. 
Published: February 2012

ABSTRACTIn this paper, the influence of the doping level at boron doped nanocrystalline diamond (BDND) films in the electrochemical determination of nitrite was reported. The morphology and the structure modifications as function of the boron doping level increase were observed. Two different doping levels were considered. A BDND film with a doping level of 30.000 ppm and one another with a doping level of 10.000 ppm was used. The columnar growth for the 30.000 ppm BDND led to a higher surface roughness and also to a greater grain size when compared to that 10.000 ppm BDND. The Raman spectra shown higher sp2-bonded carbon amount in grain boundary for the 10.000 ppm BDND film due to decrease of the grain size. The morphological and structural modifications of the BDND films were crucial for nitrite oxidation process. The 30.000 ppm BDND electrode presented a better sensitivity to the nitrite oxidation and a lower detection limit (DL) on the “as-grown” condition, while the 10.000 ppm BDND electrode presented a better analytical sensitivity and a lower DL after the surface pre-treatment with hydrogen plasma.
Weak Bonding Effect on the Ultralow Thermal Conductivity of Germanium Nanodot Arrays in Silicon
Authors: Gillet Jean-Numa 
Published: February 2012

ABSTRACTThe thermoelectric figure of merit ZT depends on the thermal conductivity inverse. uperlattices with periodic thin layers were studied to obtain ZT > 1 due to phonon confinement between their layers. Unfortunately, their synthesis with ZT higher than 1 is hazardous due to lattice mismatches forming dislocations and cracks. Nanowires with low dimensionalities were also proposed. However, as the superlattices, they decrease the thermal conductivity in only one propagation direction. In experiments, these one-dimensional insulating materials usually fail to beat the lowest limit of amorphous Si (+/- 1 W/m/K). In this theoretical study, three-dimensional Ge quantum dot arrays in Si are proposed to obtain an extreme thermal-conductivity reduction. Two decrease effects are shown from a molecular supercrystal model. First, low phonon group velocities are computed by lattice dynamics. Second, near-field scattering is exalted assuming weak interface bonding. This prediction can lead to a significant ZT increase. Indeed, a thermalconductivity global minimum λ* = 0.009 W/m/K is predicted for a Si/Ge supercrystal with nanodot spacing of +/- 30 nm and Ge concentration of +/- 12.5 Ge at.%. This ultralow λ* is computed at 300 K assuming that all Ge nanodots are weakly bonded and scatter the phonons at the Si-Ge interfaces in the geometrical limit. Thermal conductivity evolution is analyzed with respect to the weakly-bonded Ge nanodot density.
Laser Induced Heating of Group IV Nanowires
Authors: Anaya J. , Torres A. , Martin-Martín A. , Jiménez J. , Rodríguez A. , Rodríguez T. 
Published: February 2012

ABSTRACTSemiconductor nanowires (NWs) are fundamental structures for nanoscale devices. The excitation of NWs with laser beams results in thermal effects that can substantially change the spectral shape of the spectroscopic data. In particular, the interpretation of the Raman spectrum is greatly influenced by excitation induced temperature. A study of the interaction of the NWs with the excitation laser beam is essential to interpret the spectra. We present herein a finite element analysis of the interaction between the laser beam and the NWs. The resultas are applied to the interpretation of the Raman spectrum of bundles of NWs.
Molecular Dynamics Study of Size Dependence of Combustion of Aluminum Nanoparticles
Authors: Li Ying , Clark Richard , Nakano Aiichiro , Kalia Rajiv K. , Vashishta Priya 
Published: February 2012

ABSTRACTOxidation dynamics of three different sizes (26, 36 and 46 nm) of single aluminum nanoparticle (ANP) in oxygen environment are studied using multimillion-atom reactive molecular dynamics simulations. In the simulation, each aluminum nanoparticle is coated with an amorphous alumina shell of the same thickness (3 nm), and is ignited by heating the nanoparticle to 1100 K. The metallic aluminum and ceramic alumina are modeled by the Voter- Chen embedded atom model and the interatomic potential by Vashishta et al., respectively. Energy release rate and atomistic-level details of combustion of these single aluminum nanoparticles are investigated, along with the effect of nanoparticle size. The onset temperature of shell Al ejection is found to be independent of the ANP size, whereas the onset time of ejection and the time delay to the highest temperature change rate dT/dt depend on the size.
Energy Band Gap Modification of Graphene Deposited on a Multilayer Hexagonal Boron Nitride Substrate
Authors: Yelgel Celal , Srivastava Gyaneshwar P. 
Published: February 2012

ABSTRACTThe equilibrium geometry and electronic structure of graphene deposited on a multilayer hexagonal boron nitride (h-BN) substrate has been investigated using the density functional and pseudopotential theories. We found that the energy band gap for the interface between a monolayer graphene (MLG) and a monolayer BN (MLBN) lies between 47 and 62 meV, depending on the relative orientations of the layers. In the most energetically stable configuration the binding energy is found to be approximately 40 meV per C atom. Slightly away from the Dirac point, the dispersion curve is linear, with the electron speed almost identical to that for isolated graphene. The dispersion relation becomes reasonably quadratic for the interface between MLG and 4-layer-BN, with a relative effective mass of 0.0047. While the MLG/MLBN superlattice is metallic, the thinnest armchair nanoribbon of MLG/MLBN interface is semiconducting with a gap of 1.84 eV.
Thermal Transport Properties of Melt-Shear Oriented iPP/Carbon Nanotube Thin Films
Authors: Kalakonda Parvathalu , Gombos Erin A. , Georgiev Georgi Y. , Iannacchione Germano S. , Cebe Peggy 
Published: February 2012

ABSTRACTTransport properties of polymer nanocomposites become increasingly important for range applications with many outstanding questions remaining. Thermal conductivity is especially important in applications like temperature sensing and packaging. We chose isotactic PolyPropylene (iPP) as one of the most widely used polymers and created nano-colloidal dispersions at different weight percent concentration of carbon nanotubes (CNTs). We oriented the thin-film samples using melt-shear at 200°C and 1Hz in a Linkam microscope shearing hot stage. Thermal conductivity measurements were performed at room temperature on two iPP/CNT sheared thin-film samples (1% and 5% CNT content) both parallel and perpendicular to the shear direction as well as a pure iPP sheared thin-film, prepared using the same process. Our findings indicate that the CNTs enhance kappa by 12% for the 1% CNT sample and 35% by the 5% CNT sample compared to that measured for pure iPP. Additionally, the CNTs under shear induce a novel anisotropy to the thermal conductivity in iPP/CNTs nano-composites. We introduce an approach to extract the shear induced orientational order of thermal conductivity by the dispersed CNTs.
Tactile Sensing Using Contact Resistance in MWNT/PDMS Composites
Authors: McKelvey J. Ian , Kormendy Arpad , Chibante L.P. Felipe 
Published: February 2012

ABSTRACTA carbon nanotube polymer composite has been used to develop a flexible multi-touch tactile sensor device. Rather than employing the inherent bulk piezoresistive properties of the composite, the contact resistance between polymer and electrode was exploited to achieve finger pressure measurement with fast response. We have synthesized a series of multi-walled nanotube (MWNT) silicone composites to test the feasibility of a force sensor based on the change in surface contact resistance as a function of applied force. A single layer MWNT/polydimethyl-siloxane (PDMS) composite in the range of 1.5-3.0 % w/w nanotubes was employed as a force sensor material in an array of electrodes. It was determined that sensors based on these materials are viable as tactile sensing systems for finger-touch forces in the range of 1-100 N.
The role of three-phonon Normal processes in the thermal conductivity of graphene
Authors: Alofi Ayman , Srivastava Gyaneshwar P. 
Published: February 2012

ABSTRACTWe have studied the thermal conductivity of graphene using Callaway’s effective relax-ation time theory and by employing analytical expressions for phonon dispersion relations and vibrational density of states based on the semicontinuum model by Nihira and Iwata. It is found that consideration of the momentum conserving nature of three-phonon Normal pro-cesses is very important for explaining the magnitude as well as the temperature dependence of the experimentally measured results. At room temperature, the N-drift contribution (the correction term in Callaway’s theory) provides 94% addition to the result obtained from the single-mode relaxation time theory, clearly suggesting that the single-mode relaxation time approach is inadequate for describing the phonon conductivity of graphene.
Nanoengineering carbon nanotubes: The effects of electron irradiation on nanotube structure
Authors: McDonell Katherine , Proust Gwénaëlle , Shen Luming 
Published: February 2012

ABSTRACTA combined experimental and simulation approach into the impacts of electron irradiation on carbon nanotube morphology was conducted. Single-walled nanotubes (SWCNTs) were irradiated using a JEOL Transmission Electron Microscope (TEM) using a range of accelerating voltages varying from 90keV to 200keV and temperatures between 300K and 800K with different exposure periods (order of minutes). The effects of irradiation were observed and characterised using electron microscopy and Raman spectroscopy. Specimens were observed prior to, during and following irradiation to discern any changes that occurred in SWCNTs as a result of irradiation. Raman spectroscopy was used to characterise the different allotropes of carbon present in irradiated and non-irradiated samples of SWCNTs. Experimental conditions were mimicked using molecular dynamics simulation. SWCNTs were irradiated under conditions equivalent to experimental electron beam intensity and specimen temperature using AIREBO [1,2] and Primary Knock-on (PKA) approximation [3]. The preliminary results indicate that electron beam intensity and temperature affect the type and frequency of modification to CNT structure.
Combined AFM-SEM testing for mechanical property determination of graphene oxide paper
Authors: Wang Congwei , Barber Asa H. 
Published: February 2012

ABSTRACTA novel technique combining both atomic force microscopy (AFM) and scanning electron microscopy (SEM) is used to test the mechanical properties of densely-packed graphene oxide (GO) paper. Individual beams of GO paper with variable widths were prepared using focussed ion beam (FIB) microscopy and tensile tested to failure using the AFM while observing with SEM. A variation in the tensile strength of the GO paper beams up to 64.8 MPa was recorded in the vacuum testing condition. An increase in breaking stress of GO paper with decreasing sample width was determined and proposed as being due to fewer defects present in GO beams of smaller width.
Comparison Between the Phase Transition of Physically Confined Cyclohexane and 1-Decanol inside Nano Porous Silica
Authors: Bauer Hillary C. , Safiq Alexandrea D. , Dulmaa Jargalsaikhan , Khraisat Amer S. , Amanuel Samuel 
Published: February 2012

ABSTRACTThe thickness of non-freezing interfacial 1-decanol molecules has been estimated to be 1.44 ± 0.07 nm. This is smaller than what is estimated for cyclohexane, 2.25 ± 0.14nm. Furthermore, these interfacial molecules have higher density than corresponding bulk cyclohexane and 1-decanol, respectively. However, the change in density of the interfacial molecules is more significant in the case of cyclohexane than 1-decanol. This suggests that the cyclohexane molecules near the walls of the pore are more tightly packed than 1-decanol molecules. Presumably, this is due to the difference in size and shape of the molecules. Cyclohexane, a more spherical molecule, can easily be packed in smaller pores than the longer 1-decanol.
Influence of an Applied Electric Field on the Conduction Characteristics of a Bithienyl-Capped Biphenylene and Biphenyl-Capped Oligothiophenes in Organic Field-Effect Transistor Structures
Authors: Keil Christopher , Müntze Frieder , Schiek Manuela , Lützen Arne , Schlettwein Derck 
Published: February 2012

ABSTRACTThin films (50 nm) of 2,5-di-4-biphenylthiophene (PPTPP), 5,5´-di-4-biphenylyl-2,2´-bithiophene (PPTTPP) and 4,4´-di-2,2´-bithienylbiphenyl (TTPPTT) were vapor-deposited on microstructured gold (source- and drain-) electrode arrays on thermal SiO2 as gate dielectric with underlying Si serving as gate electrode. The films were studied in their field-effect characteristics during film growth and subsequent to it. A decay of specific conductivity and of charge carrier mobility was observed in subsequent measurements. During annealing without an applied field the films recovered but showed a second decay as soon as an electric field was applied again for repeated characterization. Induced dipoles and subsequent structural changes as well as chemical interactions with the SiO2 interface are discussed as possible origins of these observations.
Application of hopping theory for the prediction of charge mobility in amorphous organic materials
Authors: Sohlberg Karl , Lee Choongkeun , Waterland Robert 
Published: February 2012

ABSTRACTThe application of hopping theory for the prediction of charge (hole) mobility in amorphous organic molecular materials is studied in detail. Application is made to amorphous cells of N,N’-diphenyl-N,N’-bis-(3-methylphenylene)-1,1’-diphenyl-4,4’-diamine (TPD), N4,N4’-di(biphenyl-3-yl)-N4,N4’-diphenylbiphenyl-4,4’-diamine (mBPD), 1,1-bis-(4,4’-diethylaminophenyl)-4,4-diphenyl-1,3,butadinene (DEPB), N1,N4-di(naphthalen-1-yl)-N1,N4-diphenylbenzene-1,4-diamine (NNP), and N,N’-bis[9,9-dimethyl-2-fluorenyl]-N,N’-diphenyl-9,9-dimethylfluorene-2,7-diamine (pFFA). Detailed analysis of the computation of each of the parameters in the equations for hopping rate is presented, including studies of their convergence with respect to various numerical approximations. Based on these convergence studies, the most robust practical methodology is applied to investigate the dependence of mobility on such parameters as the monomer reorganization energy, the monomer-monomer coupling and the material density. The results give insight into what factors should be controlled to develop materials with higher (or lower) charge (hole) mobility, and what will be required to improve the accuracy of predictions of mobility in amorphous organic materials.
Multifunctional Dendritic Architectures: An Investigation of their Mechanical Properties
Authors: Zhou Haixia , Richter Marcel , von Klitzing Regine , Haag Rainer 
Published: February 2012

ABSTRACTThe paper deals with the synthesis and investigation of mechanical properties of multifunctional polyglycerol nanogels which consist of PEG with different chain lengths (glycerol, PEG 400, PEG 400-DGE, and PEG 1500). Their swelling behavior, elasticity, and stiffness are discussed in correlation with the PEG chain length. The nanogels built of PEG 400 exhibited most interesting and promising features and show the highest elasticity.
Analysis of Zinc Compound Buffer Layers in Cu(In, Ga)(S, Se)2 Thin Film Solar Cells by Synchrotron-Based Soft X-Ray Spectroscopy
Authors: Lauermann I. , Bär M. , Ennaoui A. , Fiedeler U. , Fischer Ch-H. , Grimm A. , Kötschau I. , Lux-Steiner M. Ch. , Reichardt J. , Sankapal B. R. , Siebentritt S. , Sokoll S. , Weinhardt L. , Fuchs O. , Heske C. , Jung C. , Gudat W. , Karg F. , Niesen T.P. 
Published: February 2012

AbstractZinc-based buffer layers like ZnSe, ZnS, or wet-chemically deposited ZnO on Cu(In, Ga)(S, Se)2 absorber materials (CIGSSe) have yielded thin film solar cell efficiencies comparable to or even higher than standard CdS/CIGSSe cells. However, little is known about surface and interface properties of these novel buffer layers. In this contribution we characterize the specific chemical environment at the absorber/buffer-interface using X-ray Emission Spectroscopy (XES) and Photoelectron Spectroscopy (PES) in a complementary way. Evidence of intermixing and chemical reactions is found for different buffer materials and deposition methods.
Determination of anti-oxidant capacity and content of phenols, phenolic acids, and flavonols in Indian and European gooseberry
Authors: Filipiak-Szok Anna , Kurzawa Marzanna , Szłyk Edward 
Published: February 2012

AbstractPhenolic acids and derivatives of quercetin in Indian (amla) and European gooseberry were determined by high-performance liquid chromatography with diode array detector. The calibration curves were constructed using phenolic compounds standards (the coefficient of determination (R 2) was 0.9990–0.9997 for phenolic acids and 0.9989–0.9994 for flavonols, respectively). The lowest detection limit was 0.28 mg L−1 and 0.35 mg L−1 for hyperoside and gallic acid, respectively, whereas the highest was 1.80 mg L−1 and 7.98 mg L−1 for quercetin and chlorogenic acid, respectively. The quantification limits calculated were 0.85–24.04 mg L−1 for hyperoside and chlorogenic acid, respectively. The predominant phenolic acid in amla and gooseberry is gallic acid: (5.37 ± 0.04) mg per 100 g of dry mass (d.m.) and (3.21 ± 0.03) mg per 100 g of d.m., respectively. The next one was caffeic acid, 0.65–1.22 mg per 100 g of d.m., followed by p-coumaric acid, 0.84–1.17 mg per 100 g of d.m. Out of the flavonols, rutin is predominant: (3.11 ± 0.13) mg per 100 g of d.m. and (2.12 ± 0.03) mg per 100 g of d.m., respectively. Anti-oxidant activity was also determined.
Education Policy as Proto-fascism: The Aesthetics of Racial Neo-liberalism
Authors: Webb P. , Gulson Kalervo 
Published: February 2012

Education Policy as Proto-fascism: The Aesthetics of Racial Neo-liberalismWe argue that neo-liberal educational policy has emerged as a proto-fascist governmentality. This contemporary technology relies on State racisms and racial orderings manifested from earlier liberal and neo-liberal practices of biopower. As a proto-fascist technology, education policy, and school choice policies in particular, operate within a racial aesthetics that connects ultra-nationalisms with microfascisms of racialized bodies. We discuss historical examples of liberal school segregation and residential schools in relation to contemporary examples of chartered ethnic-identity schools to illustrate the complexities of proto-fascist education policy.
State Education as High-Yield Investment: Human Capital Theory in European Policy Discourse
Authors: Gillies Donald 
Published: February 2012

State Education as High-Yield Investment: Human Capital Theory in European Policy DiscourseHuman Capital Theory has been an increasingly important phenomenon in economic thought over the last 50 years. The central role it affords to education has become even more marked in recent years as the concept of the ‘knowledge economy’ has become a global concern. In this paper, the prevalence of Human Capital Theory within European educational policy discourse is explored. The paper examines a selection of policy documents from a number of disparate European national contexts and considers the extent to which the ideas of Human Capital Theory can be seen to be influential. In the second part of the paper, the implications of Human Capital Theory for education are considered, with a particular focus on the possible ramifications at a time of economic austerity. In problematizing Human Capital Theory, the paper argues that it risks offering a diminished view of the person, a diminished view of education, but that with its sole focus on economic goals leaves room for educationists and others to argue for the educational, social, and moral values it ignores, and for the conception of the good life and good society it fails to mention.
Foucault, Governmentality, Neoliberalism and Adult Education - Perspective on the Normalization of Social Risks
Authors: Kopecký Martin 
Published: February 2012

Foucault, Governmentality, Neoliberalism and Adult Education - Perspective on the Normalization of Social RisksThe article deals with the relevance of the work of Foucault to critical analysis of the political concept of lifelong learning that currently dominates. This concept relates to the field of adult education and learning. The article makes reference to the relatively late incorporation of Foucault's work within andragogy. It shows the relevance of Foucault's concept of a subject situated within power relations where the relation between knowledge and power plays a key role. The analysis of changing relations between knowledge and power will help us to understand important features of neoliberal public policies. The motif of human capital is key. The need to continually adapt to the changing economic and social conditions follows on from the neoliberal interpretation of learning, and the individual is to blame for failure on the labour market or in life generally.
The Bologna Process as a New Public Management Tool in Higher Education
Authors: Štech Stanislav 
Published: February 2012

The Bologna Process as a New Public Management Tool in Higher EducationThis essentially polemical article questions whether the Bologna Process (BP) is necessary (and desirable) in the adaptation of universities to the new social conditions or whether it is a Trojan horse sent out to introduce neo-liberal changes in the field of higher education. First, it addresses the circumstances surrounding the origins of the Bologna Declaration, demonstrating that it enabled the instrumental logic of the marketization and commodification of education to pervade universities traditionally conceived of as cultural institutions of knowledge. It then investigates the eight declared objectives of Bologna and, finally, summarises the consequences that can be firmly established ten years after the event. These include the fact that three of the pillars of the BP can be interpreted as responding to the requirements of neoliberal New Public Management; namely, study structure (flexibility and market-driven profiles), credits (standardization, mobility and effectiveness) and quality assurance (external control). In conclusion, the paper suggests that the BP primarily represents a problem in understanding a situation that displays signs of the radical transformation of the social function of one dimension of societal life - higher education. Although it is clearly an adaptive reaction to the (neoliberal) transformation of society, it has also become part of the ideological games played by certain special-interest groups and, as such, we must make continual attempts to gain a deeper understanding of it.