bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anderson Localization of Phonons in Random Multilayer Thin Films
Authors: Frachioni Anthony , White Bruce 
Published: May 2012

ABSTRACT1020 Joules of energy are generated by the United States each year; 60% of this energy is lost to waste heat [1]. Thermoelectric based energy scavenging has tremendous potential for the recovery of significant quantities of this waste heat. However, utilization of thermoelectric devices is limited due to relatively low energy conversion efficiency and the utilization of relatively scarce materials. This work focuses on generating sustainable and efficient thermoelectric materials through modifications to the lattice vibrations of materials with excellent thermoelectric electronic properties (Seebeck coefficients larger than 500 μV/K). In particular, Anderson localization of phonons in random multilayer thin films has been explored as a means for reducing lattice thermal conductivity to values approaching that of aerogels (∼10 mW/m-K). Silicon has been a sample of choice due to its high crust abundance and Seebeck coefficient. Reverse non-equilibrium molecular dynamics simulations have been utilized to determine the thermal conductivity of structures of interest. Simulations with pure Lennard-Jones argon solids have been performed to establish a methodology and to characterize the effect of different kinds of disorder prior to the examination of silicon. The simulation results indicate that mass disorder confined to randomly selected planes to be an effective way in which to reduce lattice thermal conductivity with the lattice thermal conductivity decreasing by a factor of thirty (to 4 mW/m-K) in the argon case and a factor of over ten thousand (to 15 mW/m-K) for silicon. Based on models in which the charge carrier mean free path is limited by scattering from the planes with mass disorder, the mobility of silicon is expected to reach values of 10 cm2/V-s. At this mobility the thermoelectric figure of merit, ZT, (utilizing the Wiedeman-Franz law to calculate the electronic thermal conductivity) varies between 4.5 and 11 as the mass ratio of the disordered planes is varied from 4 to 10 in 20% of the lattice planes. These results indicate that the pursuit of nanostructured thermoelectric materials in the form of random multilayers may provide a path to efficient and sustainable thermoelectric materials.
Analytical Model of Raman Enhancement by Metal Nanoparticles
Authors: Sun Greg , Khurgin Jacob B. 
Published: May 2012

AbstractWe present an analytical model for the enhancement of molecular Raman process by metal nanoparticles. The result is compared with that of a PL process. Although both processes are similar in the sense that they are both a two-photon process in which one photon is absorbed and another photon at a different frequency is emitted, the SP enhancement mechanisms for these two processes have some rather distinct features. In addition to stronger enhancement, the Raman process shows no sign of quenching ever taking place even when the molecule is placed right at the surface of the metal nanoparticle – a situation that will lead to strong quenching effect in PL measurement. Significant advantages of our analytical approach include not just predications that are consistent with experimental observations, but rather a clear insight for the actual physical process at work.
Dental anomalies and clinical features in patients with maxillary canine impaction
Authors: Mercuri Emanuele , Cassetta Michele , Cavallini Costanza , Vicari Donatella , Leonardi Rosalia , Barbato Ersilia 
Published: May 2012

Abstract

Objective:
To analyze the prevalence, distribution, clinical features, and relationship with dental anomalies of maxillary canine impaction.

Materials and Methods:
The complete pretreatment records of 1674 orthodontic patients were examined. Subjects with maxillary impacted canines were divided into two study groups: a palatally displaced canine (PDC) group (114 patients) and a buccally displaced canine (BDC) group (37 patients). These were compared to a control group of 151 patients who were randomly selected from the initial sample without maxillary canine impaction. The significance of associations between canine impaction and dental and clinical features and anomalies was examined with the chi-square test.

Results:
PDC patients presented with normal overjet and facial profile and a lower degree of dental arch crowding in comparison to the control patients. PDC patients showed a higher prevalence of impaction of other teeth, dental aplasia, transposition, and peg-shaped maxillary lateral incisors (odds ratios 3.3, 2.6, 8.3, and 5.8, respectively).

Conclusion:
PDC was frequently the only orthodontic problem of patients. BDC group patients did not present with notable differences in clinical and dental features or dental anomalies compared to control subjects.
Sintering of mullite–β-eucryptite ceramics with very low thermal expansion
Authors: García-Moreno Olga , Fernández Adolfo , Torrecillas Ramón 
Published: May 2012

Abstract
Sintering of composite ceramic materials with an appropriate proportion of mullite and β-eucryptite to obtain a very low thermal expansion material has been tested by conventional and spark plasma sintering methods. The adjustment of the thermal expansion coefficient of the composites was performed by means of dilatometries and modifying the mullite–β-eucryptite proportions in the starting materials. Control of the reactivity between both phases at high temperature is the key to controlling not only the sinterability of the composites in the solid state, but also to controlling the final expansion properties of the material. X-ray diffraction with Rietveld refinement and field emission scanning microscopy have been used to characterize the sintered materials, together with some mechanical characterization.
Temperature-dependent 57Fe Mössbauer spectroscopy and local structure of mullite-type Bi2(Fe
x
Al1
–

x
)4O9 (0.1≤x≤1) solid solutions
Authors: Weber Sven-Ulf , Gesing Thorsten , Röder Jens , Litterst F. Jochen , Fischer Reinhard X. , Becker Klaus-Dieter 
Published: May 2012

Abstract
Oxides of the chemical composition Bi2(Fe
x
Al1
–

x
)4O9 (0.1≤x≤1) possessing a mullite-type structure have been investigated using 57Fe Mössbauer spectroscopy in the temperature range between room temperature and 1073K. The spectra have been fitted with two quadrupole doublets for Fe3
+ ions in octahedral and tetrahedral oxygen coordination. The distribution of iron on the two inequivalent structural sites has been determined from the relative areas of the subspectra. The site occupancy is found to be random within experimental error: it does not exhibit any preference of iron for the octahedral or tetrahedral sites, either as a function of temperature or with a dependence on the composition of the solid solutions.
Single crystal growth and characterization of mullite-type Bi2Mn4O10
Authors: Burianek Manfred , Krenzel Thomas F. , Schmittner Martin , Schreuer Jürgen , Fischer Reinhard X. , Mühlberg Manfred , Nénert Gwilherm , Schneider Hartmut , Gesing Thorsten M. 
Published: May 2012

Abstract
A part of the pseudo-binary join Bi2O3–Bi2Mn4O10 of the ternary system Bi2O3–MnO–MnO2 was examined using thermo-analytical methods. Because Bi2Mn4O10 melts incongruently single crystals of up to 20mm in diameter were grown by the top seeded solution growth method in the temperature range from about 1223K to 1173K. Single crystal neutron diffraction confirmed the principles of the crystal structure of Bi2Mn4O10 but revealed much smaller distortions of the cation coordination polyhedra. In contrast to the anisotropy observed in other mullite-type Bi containing compounds, the linear thermal expansion of Bi2Mn4O10, as studied by means of dilatometry and X-ray powder diffraction techniques, is characterized by α
11 > α
33>α
22 at room temperature. The relatively large expansion along the
a
-axis can be attributed to the two oxygen atoms bridging two corner shared MnO5 tetrahedral pyramids which alternate with the structural void between two adjacent Bi3
+ cations.
Synthesis and electrical conductivity of mullite-type Bi2Al4O9 and (Bi,Ca)2Al4O9 ceramics
Authors: Wei Wen-Cheng James , Chuang S. Y. , Hu Y. C. , Schneider Hartmut 
Published: May 2012

Abstract
Mullite-type Bi2Al4O9 is a potential material for electrolytes in solid oxide fuel cells. Colloidal dispersed homogeneous mixtures of commercial, submicron Bi2O3, Al2O3 and CaCO3 powders were used to fabricate mullite-type Bi2Al4O9 and (Bi,Ca)2Al4O9 by means of reaction sintering in the solid state or in liquid-phase assisted processes. The products were characterized using X-ray diffraction, scanning and transmission electron microscopy, and the sintering density was compared to two conventional sintering runs. This showed that the formation of the mullite-type Bi2Al4O9 proceeds via dissolution of Al2O3 in Bi2O3 at the temperatures > 750°C. Details on the formation mechanisms of mullite phase, electrical conductivity versus the residual γ-Bi24Al2O39 phase, and effects of Ca-dopant are reported.
An investigation of the microstructure and properties of the explosively welded Gr5–SS304 clad plates for golf heads
Authors: Zhao Hui , Zhou Yinggang , Li Pingcang , Huang Zhanghong 
Published: May 2012

Abstract
In this paper, Gr5 alloy and 304 stainless steel were joined by explosive welding. In order to improve the bond strength of the clad plates, a thin (2 mm) titanium sheet was introduced as an interlayer between Gr5 and SS 304. Accordingly, microstructure, hardness, tensile-shearing, and bending tests were evaluated in detail. Optical microscopy and scanning electron microscopy revealed that the interface between Gr5 alloys and the interlayer shows a slightly wavy morphology. The interface between the interlayer and SS304 shows a wavy structure. No distinctive separation, crack, or tear were observed in both interfaces. Line scan results indicate that there is no diffusion area at both bonding interfaces. Also, tensile-shearing and bending tests results showed that the bonding is acceptable.
Effect of cerium and aluminium on the hot-deformation behaviour of magnesium
Authors: Prasad Braj K. , Narayan Sashi P. , Modi Om P. , Ramakrishnan Nrarayanrao , Kumar Arun M. , Sachdev Anil K. 
Published: May 2012

Abstract
This study examines the response of pure Mg and its alloys, both binary Mg–Ce and ternary Mg–Al–Ce, during compression testing over a wide range of (true) strain rates and temperatures. Process maps were generated by plotting the instability parameter and efficiency of energy dissipation for microstructural evolution as a function of test temperature and strain rate. Microstructural features of each of the deformed samples were examined to generate a microstructure/micromechanism map as a matrix that was overlaid on the process map drawn in the temperature–strain-rate space. The combination of both maps delineated the desirable “safe” process window for each of the materials. Addition of 0.5% Ce to pure Mg reduced the extent of the “safe” process window despite increasing the flow stress, while alloying with both Ce and Al widened this window as determined by the extent of the desirable DRX domain. The process maps in general suggest a much wider range of temperature and strain rate for “safe” deformation compared to the microstructure maps.
Plasticity enhancement in centrally confined Zr-based bulk metallic glass
Authors: Tariq Naeem ul Haq , Awais Hasan Bin , Akhter Javaid Iqbal , Naeem Muhammad , Ahmad Atique 
Published: May 2012

Abstract
In the present work, a new idea is presented to enhance the plasticity of Zr65.5Cu22.4Al5.6Ni6.5 bulk metallic glass. A considerably large compressive plastic deformation (over 8%) was achieved by confining Zr65.5Cu22.4Al5.6Ni6.5 bulk metallic glass from its center. Numerical analysis was also carried out to investigate the stress distribution under the same mechanical conditions. It was revealed that loading induced high stress gradients facilitating large plastic strains through the generation of dense multiple shear bands.
Effect of titanium on the as-cast microstructure and impact toughness of hypereutectic high-chromium cast iron
Authors: Huang Zhifu , Xing Jiandong , Gao Yimin , Zhi Xiaohui 
Published: May 2012

Abstract
The effect of titanium on the as-cast microstructure of a hypereutectic high-chromium cast iron was investigated by means of optical microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results indicate that the primary M
7C3 carbides are refined and spheroidized with the addition of a suitable amount of titanium. TiC is found in the primary carbide by energy dispersive spectroscopy analysis. The mechanism of titanium modification on the microstructure of the alloy is also discussed. In addition, the impact test result indicates that, compared with the hypereutectic high-chromium cast iron without titanium addition, the impact toughness value of hypereutectic high-chromium cast iron with titanium additions is improved and approximately reaches 6.4 J · cm−2.
Cyclic fibre texture in hot extruded Ni50Mn29Ga21
Authors: Chulist Robert , Skrotzki Werner , Oertel Carl-Goerg , Böhm Andrea , Brokmeier Heinz-Günter , Lippmann Thomas 
Published: May 2012

Abstract
The cyclic texture in polycrystalline 5M Ni50Mn29Ga21 magnetic shape-memory alloy fabricated by hot extrusion was investigated with high-energy synchrotron radiation, neutron diffraction, and electron backscatter diffraction. Combination of these techniques reveals that the texture of the hot extruded sample is quite complex. It is composed of components related to the radial direction and rotated around the extrusion axis. Additionally, the dominant texture components change from the centre to the edge of the rod. The recrystallized grains contain many twins with the trace of the twin boundaries preferentially aligned along the extrusion and radial direction showing the cyclic nature of the texture and microstructure. The results are discussed with respect to deformation mode, phase transformations, starting grain structure, and texture.
Rod-like structure and microhardness during directional solidification of Sn-1wt.%Cu eutectic alloy
Authors: Hu Xiaowu , Ai Fanrong , Jiang Fugang 
Published: May 2012

AbstractSn-1wt.%Cu hypereutectic alloy was directionally solidified upward at a constant temperature gradient (G = 12 K · mm–1) in a wide range of growth velocities (V = 1–250 μm · s–1) using an improved Bridgman-type directional solidification furnace. The microstructure was observed to be a Cu6Sn5 rod in the matrix of β-Sn from the directionally solidified Sn-1wt.%Cu samples. The rod spacing (λ), rod diameter (d), and microhardness (HV) were measured from transverse sections of the samples. The experimental results showed that the rod spacing and rod diameter decreased with increasing growth velocity, while the microhardness increased with increasing growth velocity. The dependences of the rod spacing (λ), rod diameter (d), and microhardness (HV) on the growth velocity (V) were determined by using linear regression analysis, given as: λ = 10.49V−0.47, d = 2.1V−0.37 and HV = 9.33V0.11, respectively. The dependences of the microhardness on the rod spacing and rod diameter were also investigated, and the relationships between them were obtained by using linear regression analysis, given as: HV = 16.4λ−0.235 and HV = 11.8d−0.245.
Formation of Al67Cu23Fe10 quasicrystals by microwave heating
Authors: Mihoc Carmen , Schick Daniel , Lütgens Matthias , Lathe Christian , Burkel Eberhard 
Published: May 2012

AbstractThe present work was carried out to compare the formation of single icosahedral phase during conventional heating and microwave processing. Al67Cu23Fe10 alloy powder was synthesized from high purity (99.9%) powder elements by mechanical alloying. Differential scanning calorimetry combined with in-situ synchrotron energy dispersive X-ray diffraction was used to identify the main solid state reactions and the phase evolution of the powders. Inductive microwave processing in the magnetic field anti-node was performed to obtain the quasicrystalline phase in only a few seconds. Due to the rapid cooling of the sample it was possible to stabilize the icosahedral phase against its competing quasicrystalline approximants. Laboratory X-ray diffraction analysis was used to characterise the atomic structure of the specimen and scanning electron microscopy was used to characterise the microstructure after the microwave processing.
A comparative study of microstructure, compressive, and fracture properties of Ti3Al-based intermetallics produced via powder metallurgy, and melting and casting processes
Authors: Dimcic Biljana , Stasic Jelena , Radic Olivera , Bozic Dusan 
Published: May 2012

AbstractA comparative study of the microstructure, compressive properties, and fractography of Ti3Al and Ti3Al–Nb intermetallics produced via powder metallurgy and standard vacuum melting and casting processes has been carried out. Non-porous compacts were obtained via vacuum hot pressing of powders produced by mechanical alloying. Prior to compression tests, all samples were homogenized by a solution treatment at 1050°C (α + β region), followed by water quenching. The compression tests were performed from room temperature to 500°C in vacuum at a strain rate of 2.4 × 10–3s–1. Detailed microstructural characterization was conducted using scanning electron microscopy, followed by energy dispersive X-ray spectroscopy and X-ray diffraction analysis. Values of compressive mechanical properties of compacts were higher than those of castings. Fracture topography was examined by scanning electron microscopy. A correlation between ductility and the fracture mode exists for all materials.
Nanoindentation of pseudoelastic NiTi containing Ni4Ti3 precipitates
Authors: Young Marcus L. , Frotscher Matthias , Bei Hongbin , Simon Tobias , George Easo P. , Eggeler Gunther 
Published: May 2012

Abstract
Depending on the processing method, pseudoelastic NiTi alloys can have small, lenticular Ni4Ti3 precipitates; however, the mechanical properties of these precipitates are not well understood. By performing nanoindentation with a spherical indenter, Ni4Ti3 precipitates within a pseudoelastic NiTi alloy were examined. Scanning electron microscopy was used to examine the indents after nanoindentation. After unloading, the hardness and remnant depth ratios of the indents in the Ni4Ti3 precipitates, the NiTi matrix, and the “average” NiTi alloy were compared. To decouple the effects of elasticity from those of pseudoelasticity, similar nanoindentation experiments were performed on an NiAl sample and compared with results from the NiTi sample.
Phase relations in the ZrO2-Sm2O3-Y2O3-Al2O3 system: experimental investigation and thermodynamic modelling
Authors: Fabrichnaya Olga , Savinykh Galina , Zienert Tilo , Schreiber Gerhard , Seifert Hans J. 
Published: May 2012

Abstract
Sub-solidus phase relations in the ZrO2-Sm2O3-Y2O3 and Sm2O3-Al2O3-Y2O3 systems were experimentally studied at 1523-1873 K and thermodynamic databases for these systems were developed. Analysis of phase equilibria in the Sm2O3-Y2O3-Al2O3 system indicated that REAM phase (Sm,Y)4Al2O9 is not stable in the Sm2O3 rich-composition. Therefore, the stability limit of the Sm4Al2O9 phase was established experimentally and thermodynamic parameters of the Sm2O3-Al2O3 system were re-optimised. The eutectic melting in the Sm2O3-Y2O3-Al2O3 system was investigated using differential thermal analysis and scanning electron microscopy. The results obtained were used to assess the mixing parameter of the liquid phase. A new description of binary system was introduced into the database of the ZrO2-Sm2O3-Al2O3 system and phase diagrams were re-calculated. The obtained thermodynamic databases were combined with literature data for the ZrO2-Y2O3-Al2O3 system and a thermodynamic database for the ZrO2-Sm2O3-Y2O3-Al2O3 system was developed.
Urinary 5-HIAA Excretion is not Increased in Patients with Head and Neck Paragangliomas
Authors: Van Hulsteijn Leonie T. , Van Duinen Nicolette , Romijn Johannes A. , Smit Johannes W.A. , Corssmit Eleonora P.M. 
Published: May 2012

Background Case reports have documented carcinoid-like features in head and neck paragangliomas (HNPGLs), which, in addition to catecholamine storing granules, may also contain granules with serotonin. Serotonin is metabolized to 5-hydroxyindoleacetic acid (5-HIAA). Aim To assess the urinary excretion rates of 5-HIAA and catecholamines in HNPGL patients. Methods In 114 consecutive HNPGL patients, normetanephrine, metanephrine, norepinephrine, epinephrine, VMA, dopamine, 3-methoxytyramine and 5-HIAA excretion rates were measured in two 24-hour urinary samples. Increased excretion rates were defined as an increase of the average hormone excretion rate of 2 urine samples above the reference range. In all patients with catecholamine excess, intrathoracic and abdominal paragangliomas were excluded by 123I-MIBG scintigraphy, MRI and/or CT. Genetic screening for mutations in genes of the succinate dehydrogenase (SDH) family was performed. Results Mean urinary 5-HIAA excretion rate was 14±9 μmol/24 hours (reference range 10–44 μmol/24 hours). Urinary 5-HIAA excretion was slightly increased in only 1 patient (48 μmol/24 hours). None of the 50 patients (44%) with increased urinary excretion rates of catecholamines and/or their metabolites had elevated 5-HIAA excretion. Conclusion Urinary 5-HIAA excretion is within the normal reference range in almost all HNPGL patients. Therefore, this parameter has no clinical relevance in the routine clinical assessment of HNPGL patients.
Targeting the isoprenoid pathway in choleste biosynthesis: An approach to identify isoprenoid biosynthesis inhibitors
Authors: Liebl Maximilian , Olander Florian , Müller Christoph 
Published: February 2025

AbstractThe development of novel cholesterol biosynthesis inhibitors is a task of major concern due to the diverse roles of cholesterol and its precursors in physiological processes. Therefore, appropriate screening assays are required, which can be used to identify and quantify specific inhibitors targeting the desired enzyme. Here, we developed a whole‐cell screening assay based on a HL60 cell line, which can be used to characterize inhibitors interacting with enzymes of the isoprenoid part of cholesterol biosynthesis. Due to the change of the isoprenoid pattern under enzyme inhibition, an identification of the targeted enzyme is possible. With the described assay, we can distinguish between free and pyrophosphorylated isoprenoids after enzymatic cleavage in cellular and extracellular matrices. The approach was validated in line with the European Medicines Agency guideline on bioanalytical method validation. As proof of concept, literature‐described inhibitors of the isoprenoid pathway were tested. We characterized the effect of 11 isoprenoid biosynthesis inhibitors, and we identified 6‐fluoromevalonate as an isopentenyl pyrophosphate isomerase inhibitor, a biological activity that was previously unknown. Furthermore, isoprenoid patterns revealed that, independent of the analyzed matrix, the predominant form of the detected isoprenoids were dephosphorylated isoprenoids and only small amounts were present as pyrophosphates.