Low-temperature deposition of stoichiometric HfO2 on silicon: Analysis and quantification of the HfO2/Si interface from electrical and XPS measurements

An understanding of the exact structural makeup of dielectric interface is crucial for development of novel gate materials. In this paper a study of the HfO₂/Si interface created by the low-temperature deposition ultrathin stoichiometric HfO₂ on Si substrates by reactive sputtering is presented. Analysis, quantification and calculation of layer thickness of an HfO₂/Hf-Si-O_x/SiO₂ gate stack dielectrics have been performed, using X-ray photoelectron spectroscopy (XPS) depth profile method, angle resolved XPS and interface modeling by XPS data processing software. The results obtained were found to be in good agreement with the high frequency capacitance-voltage (C-V) measurements. The results suggest a development of a complex three layer dielectric stack, including hafnium dioxide layer, a narrow interface of hafnium silicate and broad region of oxygen diffusion into silicon wafer. The diffusion of oxygen was found particularly detrimental to the electrical properties of the stack, as this oxygen concentration gradient leads to the formation of suboxides of silicon with a lower permittivity, κ.     

Dynamic behavior of non-uniform granular gases system with the fractal characteristic in one dimension

A one-dimensional dynamic model of polydisperse granular mixture with a power-law size distribution is presented, in which the particles are subject to inelastic mutual collisions and driven by Gaussian white noise. The particle size distribution of the mixture has the fractal characteristic, and a fractal dimension D as a measurement of the inhomogeneity of the particle size distribution is introduced. We define the global granular temperature and the kinetic pressure of the mixture, and obtain their expressions. By molecular dynamics simulations, we have mainly investigated how the inhomogeneity of the particle size distribution and the inelasticity of collisions influence the steady-state dynamic properties of the system, focusing on the global granular temperature, kinetic pressure, velocity distribution and distribution of interparticle spacing. Some novel results are found that, with the increase of the fractal dimension D, the global granular temperature and the kinetic pressure decrease, the velocity distribution deviates more obviously from the Gaussian one and the particles cluster more pronouncedly at the same value of the restitution coefficient e (0<e<1). On the other hand, as the restitution coefficient e decreases, the dynamic behavior has the similar evolution as above at the fixed fractal dimension D. The dynamic behavior changing with e and D is, respectively, presented.     

Disinfection of gram-negative and gram-positive bacteria using DynaJets® hydrodynamic cavitating jets

Cavitating jet technologies (DynaJets®) were investigated as a means of disinfection of gram-negative Escherichia coli, Klebsiellapneumoniae, Pseudomonas syringae, and Pseudomonas aeruginosa, and gram-positive Bacillus subtilis. The hydrodynamic cavitating jets were found to be very effective in reducing the concentrations of all of these species. In general, the observed rates of disinfection of gram-negative species were higher than for gram-positive species. However, different gram-negative species also showed significant differences (P. syringae 6-log₁₀ reduction, P. aeruginosa 2-log₁₀ reduction) under the same conditions. Disinfection of E. coli repeatedly showed five orders of magnitude reduction in concentration within 45-60-min at low nozzle pressure (2.1 bar).Optimization of nozzle design and operating pressures increased disinfection rates per input energy by several orders of magnitude. The power efficiencies of the hydrodynamic cavitating jets were found to be 10-100 times greater than comparable ultrasonic systems.     

Wood species identification using improved active shape model

In this paper, we propose a robust wood species identification scheme by using color wood surface images. First, a novel wood image acquirement system is devised, and the wood color image is converted into a V₁V₂I color-base image. Second, the corresponding grey histograms for V₁ and V₂ are established. Third, an improved active shape model is used to fulfill the curve deformation of the histogram curve of the standard specimen. This active shape model will then converge to the histogram curve of the test specimen. Finally, wood recognition is performed by comparing the initial and final active shape models with the histogram curve of the test specimen. We have experimentally proved that this scheme improves the mean recognition accuracy to approximately 90% for 5 wood species and that it can also be applied to the Gaussian noisy images. Moreover, the recognition accuracy can be further improved by combining this scheme with the texture feature recognition.     

Microwave absorption properties of rod-shaped Co-Ni-P shells prepared by metallizing Bacillus

The rod-shaped Co-Ni-P shells were prepared by metalling Bacillus. The microstructures and composition of the shells were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive analysis (EDS). The electromagnetic parameters were measured by the coaxial line method in the frequency of 2-18 GHz. It was found that the Bacillus were successfully coated with Co-Ni-P, and the inner structure of the shells are hollow in structure. The shells exhibit excellent microwave absorption properties in 5-17 GHz frequency. The microwave reflection loss is above −10 dB in 5.38-16.6 GHz frequency. The maximum microwave reflection loss reaches −35.83 dB at 9.12 GHz for samples thickness 2.4 mm, and the widest bandwidth for microwave reflection loss above −10 dB is about ∼5.32 GHz for samples thickness 2.0 mm. These results confirm the feasibility of applying Bacillus as biotemplates for fabrication of the metallic shells as lightweight microwave absorption materials are very promising for applications.     

The 2003 edition of the GEISA/IASI spectroscopic database

The content of the current (2003) version, GEISA/IASI-03, of the computer-accessible spectroscopic database, GEISA/IASI, is described. This “system” or database is comprised of three independent spectroscopic archives, which are (a) a database of individual spectral line parameters on 14 molecules, H₂O, CO₂, O₃, N₂O, CO, CH₄, O₂, NO, SO₂, NO₂, HNO₃, OCS, C₂H₂, N₂, and the related 51 isotopomers and isotopologues, representing 702,550 entries, in the spectral range 599-, (b) a database of spectral absorption cross-sections (6,572,329 entries related to six molecules, CFC-11, CFC-12, CFC-14, HCFC-22, N₂O₅, CCl₄), and a catalogue of microphysical and optical properties (mainly, the refractive indices) of atmospheric aerosols. The modifications and improvements, which have been implemented since the earlier editions of this database, in terms of content and management, have been explained in detail. GEISA/IASI has been created with the specific purpose of assessing the capability of measurement by the IASI instrument within the designated goals of ISSWG in the frame of the CNES/EUMETSAT European Polar System preparation.All the archived data can be handled through a user-friendly associated management software, which is posted on the ARA/LMD group web site at http://ara.lmd.polytechnique.fr.     

Spectroscopy of X2Y4 (D2h) molecules: tensorial formalism adapted to the O(3)⊃D2h chain, Hamiltonian and transition moment operators

A tensorial formalism adapted to the case of the X₂Y₄ molecules with D_2h symmetry has been developed in the same way as in the previous works on XY₄ (T_d) and XY₆ (O_h) spherical tops and XY₅Z (C_4v) symmetric tops. Here, we use the O(3)⊃D_2h group chain. All the coupling coefficients and formulas for the computation of matrix elements are given for this chain and used in the case of the Hamiltonian and transition moment operators.     

Nature of magnetic impurity induced superparamagnetism and anomalous Hall effect in β-FeSi2 single crystals

The magnetic properties of β-FeSi₂ single crystals were investigated using magnetization and anomalous Hall effect measurements. These measurements clearly show the appearance of superparamagnetism, the origin of which is attributed to defect-induced magnetic aggregates. Unlike previous reports, based on our combined analysis using magnetization and the anomalous Hall effect, we found that two kinds of aggregates, which are magnetically distinct, exist in our samples. Among the two types found, one gives an anomalous Hall term, which follows a side-jump mechanism while the other is a completely new kind, suggesting that magnetic properties of β-FeSi₂ are very unconventional. The sizes of the aggregates were estimated from our experimental data.     

Tuning the dispersion of 4f bands in the heavy-fermion material YbRh2Si2

Localized Yb 4f and itinerant Rh 4d states are subject to substantial hybridization effects in the heavy-fermion material YbRh₂Si₂. The proximity to the Fermi level and the high anisotropy in k space naturally raise questions regarding the role of these hybridization effects for the observed, unusual physical properties. Using angle-resolved photoemission spectroscopy (ARPES) we found that the non-dispersive behavior of the localized Yb f states is broken around the Γ point due to interaction with approaching Rh 4d bands. The intriguing point here is that the hybridization strength turns out to be systematically tunable by electron doping of the material. Gradual deposition of silver atoms onto the atomically clean, silicon terminated surface of YbRh₂Si₂ leads to transfer of Ag 5s charge into the Rh 4d bands. This substantially changes the energy overlap, and thus the hybridization strength, between the interacting Yb 4f and Rh 4d bands in the surface and subsurface region. The shown possibility to control the variation of the f-d hybridization at the surface of heavy-fermion materials may also be helpful for other ARPES studies on the diverse phenomena in electron-correlated materials.     

UAE, MAE, SFE-CO2 and classical methods for the extraction of Mitragyna speciosa leaves

Mitragyna speciosa, a tropical plant indigenous to Southeast Asia, is well known for its psychoactive properties. Its leaves are traditionally chewed by Thai and Malaysian farmers and manual labourers as it causes a numbing, stimulating effect. The present study aims to evaluate alkaloid yield and composition in the leaf extracts. For this purpose we have compared several non-conventional extraction techniques with classic procedures (room temperature or under heating). Dried M. speciosa leaves belonging to three batches of different origin (from Thailand, Malaysia and Indonesia) were extracted using ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) and supercritical carbon dioxide extraction SFE-CO₂, using methanol, ethanol, water and binary mixtures. The extracts were compared using an HPLC/ESI-MS analysis of mitragynine and four other related alkaloids which were present in the alkaloid fraction. The extraction technique influences both the raw product yield and the relative alkaloid content of M. speciosa leaves. Of the several methods tested, MAE in a closed vessel at 110 °C (60 W, methanol/water 1:1) gave the highest alkaloid fraction amount, while UAE with an immersion horn at 25 °C (21.4 kHz, 50 W, methanol) showed the best yield for mitragynine.This work may prove to be a useful contribution to forensic, toxicological and pharmacognosy studies. Although the potential applications of M. speciosa alkaloids clearly need further investigation, these results may facilitate the scaling-up of their extraction.     

ToF-SIMS studies of Bacillus using multivariate analysis with possible identification and taxonomic applications

In this paper we discuss the application of ToF-SIMS with an Au₃⁺ primary ion beam, combined with principal components analysis (PCA) and discriminant function analysis (DFA) for the identification of individual strains of two Bacillus species. The ToF-SIMS PC-DFA methodology is capable of distinguishing bacteria at the strain level based on analysis of surface chemical species. By classifying the data using hierarchical cluster analysis (HCA) we are able to show quantitative separation of species and of these strains. This has taxonomic implications in the areas of rapid identification of pathogenic microbes isolated from the clinic, food and environment.     

Precision improvements in the geo-fit retrieval of pressure and temperature from MIPAS limb observations by modeling CO2 line-mixing

In this paper, we present an improvement of the retrieval of pressure and temperature from the observations of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board of the environmental satellite (ENVISAT). The improvement has been obtained by integrating a state-of-the-art CO₂ line-mixing model in a two-dimensional inversion system (Geo-fit). We describe the implementation of this model in the Geo-fit system and we show its capability to reproduce the CO₂ spectral features affected by line-mixing. The upgraded analysis algorithm provides a better fit of the set of MIPAS observations analyzed by the European Space Agency (ESA) ground segment although these observations have been selected with criteria that should avoid line-mixing effects. Moreover, we show that this set of observations can be extended improving the precision of the retrieved pressure and temperature fields without increasing the computing demands. Since the CO₂Q branches are very sensitive to pressure and temperature, the capability to model accurately the line-mixing effects opens the possibility to exploit at best these spectral regions to infer pressure and temperature distributions. According to this idea, we propose a new set of spectral intervals, including the most intense CO₂Q branches. It is shown that the analysis of these intervals provides a significant improvement (up to 70%) in the precision of the retrieved pressure and temperature profiles, while using a smaller number of observations with respect to the ESA ground segment analysis. Since the knowledge of pressure and temperature is necessary for the retrieval of the altitude distribution of all the atmospheric constituents, the benefits of more precise pressure and temperature fields obtained in this work propagate into the quality of all the MIPAS products.     

Exchange-mediated contrast in CEST and spin-lock imaging

Purpose

Magnetic resonance images of biological media based on chemical exchange saturation transfer (CEST) show contrast that depends on chemical exchange between water and other protons. In addition, spin–lattice relaxation rates in the rotating frame (R_1ρ) are also affected by exchange, especially at high fields, and can be exploited to provide novel, exchange-dependent contrast. Here, we evaluate and compare the factors that modulate the exchange contrast for these methods using simulations and experiments on simple, biologically relevant samples.

Methods

Simulations and experimental measurements at 9.4 T of rotating frame relaxation rate dispersion and CEST contrast were performed on solutions of macromolecules containing amide and hydroxyl exchanging protons.

Results

The simulations and experimental measurements confirm that both CEST and R_1ρ measurements depend on similar exchange parameters, but they manifest themselves differently in their effects on contrast. CEST contrast may be larger in the slow and intermediate exchange regimes for protons with large resonant frequency offsets (e.g. > 2 ppm). Spin-locking techniques can produce larger contrast enhancement when resonant frequency offsets are small (< 2 ppm) and exchange is in the intermediate-to-fast regime. The image contrasts scale differently with field strength, exchange rate and concentration.

Conclusion

CEST and R_1ρ measurements provide different and somewhat complementary information about exchange in tissues. Whereas CEST can depict exchange of protons with specific chemical shifts, appropriate R_1ρ-dependent acquisitions can be employed to selectively portray protons of specific exchange rates.     

Analysis of some elements in three Chrysolina (Coleoptera, Chrysomelidae) species by EDXRF spectrometry

In this investigation, the concentration levels of potassium, calcium, iron, nickel and cadmium for three Chrysolina species were measured in the region of Erzurum (Turkey) located at latitude 40°17′ north and longitude 41°17′ east. The concentrations measured by energy dispersive X-ray fluorescence (EDXRF) spectrometry were analysed. Photons of 59.5 keV and 5.9 keV emitted, respectively, by an annular ²⁴¹Am and ⁵⁵Fe radioactive source were used to excite the characteristic X-rays of various elements present in the insect samples. These results are presented and discussed in this paper.     

Synthesis and characterization of β-Ni(OH)2 up grown nanoflakes by SILAR method

In this paper we report a “bottom up” approach to synthesize β-Ni(OH)₂ nanoflakes using novel successive ionic layer adsorption and reaction (SILAR) method. Ni(OH)₂ thin films have been deposited on glass substrate using aqueous alkaline nickel chloride as nickel ion source and double distilled water maintained at 353 K temperature as hydroxyl ion source. The structural, surface morphological, optical and electrical properties of films are examined. The nanocrystallinity and β-phase of Ni(OH)₂ are confirmed by X-ray diffraction and FT-IR studies. Scanning electron microscope study revealed microporous and random distribution of well up grown interlocked nanoflakes. Optical absorption studies show wide optical band gap of 3.26 eV for β-Ni(OH)₂. The electrical properties revealed that β-Ni(OH)₂ has negative temperature coefficient of resistance with p-type semiconducting behaviour. The electrochemical property studied by cyclic voltametry in 2 M KOH electrolyte solution revealed pseudo capacitive behaviour, when β-Ni(OH)₂ thin film employed as working electrode in three electrode electrochemical cell with platinum as counter electrode and saturated calomel as reference electrode. The specific capacitance of 350 F g⁻¹ is obtained with nanoflake like morphology.     

Electronic and thermodynamic properties of α-Pu2O3

Based on density functional theory+U$\text{density functional theory}+U$ calculations and the quasi-annealing simulation method, we obtain the ground electronic state for α-Pu₂O₃ and present its phonon dispersion curves as well as various thermodynamic properties, which have seldom been theoretically studied because of the huge unit cell. We find that the Pu–O chemical bonding is weaker in α-Pu₂O₃ than in fluorite PuO₂, and subsequently a frequency gap appears between oxygen and plutonium vibration density of states. Based on the calculated Helmholtz free energies at different temperatures, we further study the reaction energies for Pu oxidation, PuO₂ reduction, and transformation between PuO₂ and α-Pu₂O₃. Our reaction energy results are in agreements with available experiment. And it is revealed that high temperature and insufficient oxygen environment are in favor of the formation of α-Pu₂O₃.     

Monitoring of pathogen carrying air-borne tea dust particles by light scattering

In order to investigate whether tea (Camellia sinensis (L.) Kuntze) dust particles could be a possible carrier of the pathogen contaminated Mycobacterium a biotechnical procedure was used, and to verify the possibility of monitoring this dust, a laser based light scattering setup was designed and fabricated. Experiments were carried out using the strain Mycobacterium smegmatis mc² 155 as a model organism to study the effect on tea dust particles. Light scattering investigations on both M. smegmatis contaminated and uncontaminated tea dust particle samples were carried out as a function of scattering angle at 543.5, 594.5 and 632.5 nm wavelengths. The results have shown that the behavior of tea dust samples both with and without Mycobacterium varies significantly for all the three different incident laser wavelengths.     

Thermodynamic investigations of ternary o-toluidine + tetrahydropyran + N,N-dimethylformamide mixture and its binaries at 298.15, 303.15 and 308.15 K

The densities ρ, speed of sound u, data of o-toluidine (i) + tetrahydropyran (j) + N,N-dimethylformamide (k) and its {tetrahydropyran (j) + N,N-dimethylformamide (k); o-toluidine (i) + N,N-dimethylformamide (k)} binaries have been measured as a function of composition at 298.15, 303.15 and 308.15 K. The excess molar enthalpies, H^E data of same set of binary mixtures have also been measured over entire composition at 308.15 K. The densities and speeds of sound data of binary and ternary mixtures have been utilized to determine their excess molar volumes, V^E and excess isentropic compressibilities, κ_S^E. The observed thermodynamic properties of binary and ternary mixtures have been analyzed in terms of Graph theory. It has been observed that Graph theory correctly predicts the sign as well as magnitude of thermodynamic properties.     

Cu addition and its role in thermoelectric properties and nanostructuring in the series compounds (InSb)nCum

We have performed a comparative investigation of the series compounds (InSb)_nCu_m to assess the roles of Cu addition on the thermoelectric properties and nanostructuring in bulk InSb. Detailed temperature dependent transport properties including electrical conductivity, the Seebeck coefficient, and thermal conductivity are presented. The Seebeck coefficients of In₂₀Sb₂₀Cu (m:n = 1:20) are increased by 13 percent in magnitude if compared to those of InSb, which is responsible for the 22 percent enhancement in the highest ZT value at 687 K. Although the magnitudes of κ_L are larger than those of InSb over the entire temperature range, a remarkable reduction in lattice thermal conductivities (κ_L) was observed with measuring temperature elevation. Such changes are mainly due to the precipitation of a large number of Cu₉In₄ nanoparticles with the size of smaller than 5 nm, dispersed in the matrix observed using high resolution transmission electron microscopy (HRTEM) images.     

Rotational analysis of bands in the high-resolution infrared spectra of the three species of butadiene-1,4-d2; refinement of the assignments of the vibrational fundamentals

Samples of trans,trans and cis,cis forms of butadiene-1,4-d₂ have been synthesized and found to contain useful amounts of the cis,trans species as a contaminant. Assignments of fundamental frequencies for the three isotopomers of butadiene-1,4-d₂ have been extended and improved from investigations of their Raman spectra as well as their infrared (IR) spectra. High-resolution IR spectra have been recorded for the three isotopomers, and a rotational analysis has been completed for strong bands of each species. Ground state and some upper state rotational constants have been fit. Corresponding ground state moments of inertia compare favorably with equilibrium moments of inertia obtained from B3LYP/6-311++G** theory. Two ¹³C isotopomers are being prepared, and an improved structural analysis of butadiene will soon be available to assess how π-electron delocalization affects its structure.