Impact of bubble coalescence in the determination of bubble sizes using a pulsed US technique: Part 2 – Effect of the nature of saturating gas

Knowledge on cavitation bubble size distribution, ambient radius of bubbles is of interest for many applications that include therapeutic and diagnostic medicine. It however becomes a hard quest when increasing the ultrasonic frequency, when direct observation of bubble dynamics is no longer possible. An indirect method based on the estimation of the bubble dissolution time under pulsed ultrasound (362 kHz) is used here under optimized conditions to derive ambient radii of cavitation bubbles in water saturated with He, Ar, Xe, O₂, N₂ and air: 3.0 µm for Ar, 1.2 µm for He, 3.1 µm for Xe, 2.8 µm for O₂, around 1 µm for N₂ and air. If the pulse on-time is increased, bubble coalescence occurs, the extent of which is rather limited for Ar but extremely high for He or N₂.     

Evaluation of the brain pH using a phosphorus magnetic resonance spectroscopy technique – a comparison of women and men

The aim of this study was to determine the reference value of pH in healthy women and men using the phosphorus magnetic resonance spectroscopy technique. The brains of 65 young volunteers were examined. The intracellular pH was calculated in the group of women and the group of men. In both groups, the average pH was slightly alkaline (respectively 7.10?±?0.08 and 7.08?±?0.12). No statistically significant sex difference in brain pH was found. Thus, in case if this method is used to estimate possible brain pathology in the young population, it is not needed to take the gender factor into consideration.     

Preparation of conventional thermoelectric nanopowders by pulsed laser fracture in water: application to the fabrication of a pn hetero-junction

The technique of laser fracture in a liquid medium has been applied to the synthesis of n-type (Bi_0.95Sb_0.05)₂ (Te_0.95Se_0.05)₃ and p-type (Bi_0.2Sb_0.8)₂Te₃ semiconducting nanopowders which are the best conventional materials currently used for thermoelectric applications at ambient temperature. The nanopowders have been prepared with a high yield in an especially built-up cell. Laser fracture in water of micronsized powders has been applied, using a nanosecond Nd:YAG laser working at 532 nm. The obtained powders have been characterized by scanning and transmission electron microscopy and by X-ray diffraction. The mean diameter is about 10 nm and the phase of the initial powders is kept. To test the potentiality of these nanosized materials, we have shown the feasibility to produce a pn hetero-junction.     

Bubble population phenomena in sonochemical reactor: I Estimation of bubble size distribution and its number density with pulsed sonication – Laser diffraction method

To characterize the bubble populations (size and its number distribution) in a sonochemical reactor, a simple but powerful technique based on the Fraunhofer laser diffraction (LD) has been proposed. In this method, the acoustic wave disturbance to the laser probe in the sonochemical reaction field was eliminated by the temporal separation using pulsed sonication (pulsed LD). With this relatively simple strategy, the temporal development of the bubble size distribution could be evaluated by pulsed LD. A number density of bubbles was estimated by using a calibration data obtained with monosized standard particles. In addition, the effect of pulse length and a surfactant on the bubble population phenomena in a multibubble system are discussed.     

Precise study of the Z/γ* boson transverse momentum distribution in pp collisions using a novel technique

Using 7.3 fb?1 of pp collisions collected by the D0 detector at the Fermilab Tevatron, we measure the distribution of the variable φ(η)*, which probes the same physical effects as the Z/γ* boson transverse momentum, but is less susceptible to the effects of experimental resolution and efficiency. A QCD prediction is found to describe the general features of the φ(η)* distribution, but is unable to describe its detailed shape or dependence on boson rapidity. A prediction that includes a broadening of transverse momentum for small values of the parton momentum fraction is strongly disfavored.     

Spectroscopic determination of Fisher information on vibrational states of diatomic molecules using the example of the X 1Σ g + state of a Li2 molecule

An expression governing Fisher information of vibrational states of a diatomic molecule is obtained in the first-order Wentzel-Kramers-Brillouin (WKB) approximation, and a quantitative criterion of its applicability is proposed. The expression is determined only by the dependence of energy of vibrational levels on quantum number v and the reduced mass of the molecule; it is not related to any additional model assumptions and does not require knowledge of vibrational wavefunction. It is established that the dependence of Fisher information on v attains maximum at certain value v ₀. The efficiency of the obtained expression is demonstrated by calculating the Fisher information of vibrational levels v = 0–40 of the X ¹Σ _g ⁺ state of the ⁷Li₂ molecule. It is established that v ₀ = 23 for this electronic state. Calculation of the Fisher information of levels v = 0–38 of this state with the help of the obtained relation is in excellent (within mean-square deviation σ? = 0.01%) agreement with the results of calculation based on numerical solution of the Schrödinger equation by using the earlier-published semi-empirical potential curve of this state. At the same time, the expressions available in the literature based on the Wilson-Sommerfeld quantization rule describe the Fisher information of these levels only qualitatively (σ? = 18%). It is established that the reason for deviation for levels v = 39 (σ = 0.3%) and v = 40 (σ = 1.9%) is not related to using the WKB approximation but is due to the numerical differentiation procedure of strongly nonlinear (in the vicinity of the upper bound of v) dependence of the energy of vibrational terms on v appearing in the obtained expression.     

Measurement of the Soret,diffusion, and thermal diffusion coefficients of three binary organic benchmark mixtures and of ethanol–water mixtures using a beam deflection technique

We have measured the Soret (S _T ), diffusion (D), and thermal diffusion (D _T ) coefficients of three binary mixtures of dodecane (DD), isobutylbenzene (IB) and 1,2,3,4-tetrahydronaphthalene (TH) for a concentration of 50 wt% at a temperature of 25°C by means of an optical beam deflection cell. This relevant experimental technique was still missing from a recent benchmark campaign for the measurement of the Soret effect. The measured coefficients agree to within a few percent (10% for S _T , D of TH/IB) with the proposed benchmark values. A detailed analysis of the measurement process of the beam deflection cell, which allows for an elegant extension to include temperature gradients within the windows, is given, and improved benchmark values are suggested. In addition, ethanol–water mixtures have been investigated very carefully over a broad concentration and temperature range. Comparison with data of Kolodner and Wiegand gives a generally good agreement with some systematic deviations. Contrary to theoretical predictions, we have not been able to identify a second sign change of S _T at high ethanol concentrations.     

The proton inventory technique in a dual mechanistic system: the spontaneous hydrolysis of ethyl formate †

Ethyl formate undergoes spontaneous hydrolysis through two parallel mechanistic pathways: water catalysis and specific hydrogen-ion catalysis. The proton inventory of the water reaction at 37.0 ^°C was determined from the overall conversion curves, in H₂O/D₂O mixtures of deuterium atom fraction n, resulting in k ₁(n)=(2.1±0.1)×10^?5 s^?1 (1?n+0.42 n) (1?n+0.83 n)², in agreement with the results of six other cases of carboxylic acid derivatives. This result contributes to the validation of the accuracy of the proton inventory technique.     

Roles of Elements of a Heterostructure Based on the Topological Phase of Hg1 – xCdxTe in the Effect of PT-Symmetric Terahertz Photoconductivity

JETP Letters - It is demonstrated that the PT-symmetric terahertz photoconductivity observed in heterostructures based on thick Hg1 – xCdxTe films in the topological phase is due to the...     

Supersonic flows with small perturbations in the presence of external effects in the flow. Part 1: “Thin body of revolution”

Axisymmetric supersonic flow about a thin body of revolution with an external energy supply and an external force localized near the body surface is considered in the linear approximation. An analytic theory is constructed for calculating spatial fields of flow parameters in this case for an arbitrary dependence of external effects on the longitudinal coordinate. Formulas are derived for the pressure ratio on the surface of the thin body of revolution. The results of calculations based on the analytic theory are in good agreement with numerical data obtained from the solution of hydrodynamic equations in the Euler approximation.     

Vibrational population of the O2(b1Σ g + ) state in a low-Pressure oxygen pulsed discharge

The study of the vibrational state population of the O₂(b¹ _g ⁺ ) metastable state in a pure oxygen DC pulsed discharge is presented. The vibrational temperature is evaluated from the relative populations of v = 0, 1 and 2 states. The populations are determined from the intensities of (0-0), (1-1), (1-0) and (2-1) transitions of the atmospheric system. The most intensive (0-0) and (1-1) bands are used in the time-resolved measurements in order to determine the time evolution of the vibrational temperature during the discharge pulse.     

Application of the Transmission Line Matrix method for outdoor sound propagation modelling – Part 2: Experimental validation using meteorological data derived from the meso-scale model Meso-NH

Outdoor sound prediction is both a societal concern and a scientific issue. This paper deals with numerical simulations of micrometeorological (temperature and wind) fields for environmental acoustics. These simulations are carried out using the reference meso-scale meteorological model at the Meteo-France weather agency (Meso-NH). Meso-NH predictions at very fine scales (up to 3 m), including new developments (drag force approach), are validated both numerically and experimentally under stable, unstable and neutral conditions. Then, this information can be used as input data for the acoustic propagation model. The time-domain acoustic model is based on the Transmission Line Matrix method. Its development has also been promoted for application to outdoor sound propagation, i.e. to take into account topography, ground impedance, meteorological conditions, etc. In part 1, the presentation and evaluation of the Transmission Line Matrix method showed the relevance of this method’s use in the context of environmental acoustics. Finally, simulated noise levels under different propagation conditions were compared to in situ measurements. Satisfactory results were obtained regarding the variability of the observed phenomena.     

Spectroscopy of ammonia in the range 6626–6805 cm−1: using temperature dependence towards a complete list of lower state energy transitions

Systematic analysis of the temperature dependence of the intensity ratio between already assigned and unassigned transitions enabled the determination of the most probable energy of the lower state of the unassigned transition. Such a procedure has been applied to transitions of ¹⁴NH₃ ammonia in the range 6626–6805 cm^?1 between 130 and 300 K. This information is of great interest in the considerable task of the assignment of the complete 1.5 μm infrared spectral range where combination and overtone vibrational bands are present. 2451 transitions have been observed at different temperatures. For 2133 the line strength and for 1956 transitions the values of lower state energies were derived. Our work was compared with recent Fourier transform study covering a larger energy range (6300–7000 cm^?1) with smaller temperature range (185–296 K)     

Infrared spectrum and fourier transform spectroscopy of the 2ν1 band of OCSe: Synthesized by using a heat pipe reactor

In order to observe the infrared spectrum of OCSe, a sufficient amount was readily synthesized by using a heat pipe reactor. Thirteen vibrational bands were observed in the region of 400 ∼ 4000 cm⁻¹, seven of which have never been reported. The high-resolution FTIR spectrum of the 2ν₁ band of OCSe was recorded with a resolution of 0.005 cm⁻¹. Analysis provided molecular constants for the 2ν₁ band of ¹⁶O¹²C⁸⁰Se and ¹⁶O¹²C⁷⁸Se in natural abundance.     

Temperature-dependent pressure broadened line shape measurements in the ν 1+ν 3 band of acetylene using a diode laser referenced to a frequency comb

Using an extended cavity diode laser referenced to a femtosecond frequency comb, the P(11) absorption line in the ?? ₁+?? ₃ combination band of the most abundant isotopologue of pure acetylene was studied at temperatures of 296, 240, 200, 175, 165, 160, 155, and 150?K to determine pressure-dependent line shape parameters at these temperatures. The laser emission profile, the instrumental resolution, is a Lorentz function characterized by a half width at half the maximum emission (HWHM) of 8.3×10^?6?cm^?1 (or 250?kHz) for these measurements. Six collision models were tested in fitting the experimental data: Voigt, speed-dependent Voigt, Rautian?CSobel??man, Galatry, and two Rautian?CGalatry hybrid models (with and without speed-dependence). Only the speed-dependent Voigt model was able to fit the data to the experimental noise level at all temperatures and for pressures between 3 and nearly 360?torr. The variations of the speed-dependent Voigt profile line shape parameters with temperature were also characterized, and this model accurately reproduces the observations over their entire range of temperature and pressure.     

Relative line intensity measurement in absorption spectra using a tunable diode laser at 1.6 μm: application to the determination of 13CO2/12CO2 isotope ratio

The measurement of relative intensities in CO₂ combination bands spectrum is performed using wavelength modulation spectroscopy (WMS) and a DFB (distributed feedback) diode laser operating at 1.6 μm. The diode laser is stabilized with an external Fabry–Pérot interferometer and absorption spectroscopy is performed in a multipass gas cell. A spectrum containing spectral lines of both ¹³CO₂ and ¹²CO₂ isotopic species is recorded. The variation of laser power during frequency scanning and the line shape are taken into account to accurately extract line intensities from experimental data. The isotopic concentration ratio is deduced from the intensity ratio. Both ratios are measured with an accuracy of about 0.5% in pure CO₂. Received: 9 June 2000 / Published online: 8 November 2000     

Pressure measurement using the R fluorescence peaks and 417 cm−1 Raman peak of an anvil in a sapphire-anvil cell

In this study, synthetic sapphire crystals were used as anvils, coupled with a metal gasket, in a Merrill–Bassett-type pressure cell (sapphire-anvil cell (SAC)). Quartz and ruby chips were compressed in the cell and used as pressure calibrators for the SAC. In the sample–anvil interface, the relationship of the frequency shifts of the R1, R2 and 417 cm^?1 peaks with pressure was studied. They were constructed as new pressure calibrators. To test the applicability of the newly calibrated SAC, the Raman spectra of dolomite and calcite were measured in situ at room temperature.     

δ2H and δ18O of human body water: a GIS model to distinguish residents from non-residents in the contiguous USA

An understanding of the factors influencing the isotopic composition of body water is important to determine the isotopic composition of tissues that are used to reconstruct movement patterns of humans. The δ(2)H and δ(18)O values of body water (δ(2)H(bw) and δ(18)O(bw)) are related to the δ(2)H and δ(18)O values of drinking water (δ(2)H(dw) and δ(18)O(dw)), but clearly distinct because of other factors including the composition of food. Here, we develop a mechanistic geographical information system (GIS) model to produce spatial projections of δ(2)H(bw) and δ(18)O(bw) values for the USA. We investigate the influence of gender, food, and drinking water on the predicted values by comparing them with the published values. The strongest influence on the predicted values was related to the source of δ(2)H(dw) and δ(18)O(dw) values. We combine the model with equations that describe the rate of turnover to produce estimates for the time required for a non-resident to reach an isotopic equilibrium with a resident population.     

δ2H and δ18O of human body water: a GIS model to distinguish residents from non-residents in the contiguous USA

An understanding of the factors influencing the isotopic composition of body water is important to determine the isotopic composition of tissues that are used to reconstruct movement patterns of humans. The δ²H and δ¹⁸O values of body water (δ²H_bw and δ¹⁸O_bw) are related to the δ²H and δ¹⁸O values of drinking water (δ²H_dw and δ¹⁸O_dw), but clearly distinct because of other factors including the composition of food. Here, we develop a mechanistic geographical information system (GIS) model to produce spatial projections of δ²H_bw and δ¹⁸O_bw values for the USA. We investigate the influence of gender, food, and drinking water on the predicted values by comparing them with the published values. The strongest influence on the predicted values was related to the source of δ²H_dw and δ¹⁸O_dw values. We combine the model with equations that describe the rate of turnover to produce estimates for the time required for a non-resident to reach an isotopic equilibrium with a resident population.     

The LPCTrap experiment: measurement of the ��-��?angular?correlation in 6He+ decay using a transparent Paul trap

The LPCTrap experiment is devoted to the precise measurement of the ??-?? angular correlation parameter, a _?|? , in the pure Gamow-Teller decay of ⁶He⁺. This experiment is motivated by the search of the presence of tensor type contributions in the weak interaction. The radioactive source is confined in a transparent Paul trap installed at LIRAT, the low energy beam line of the SPIRAL facility. The ??-?? correlation is studied by measuring the time of flight of the recoil ions detected in coincidence with the ?? particles. During the last experiment, a total of 4 × 10⁶ coincidence events have been recorded which would enable to determine the coefficient with a statistical uncertainty of 0.5%. The status of the analysis is presented in this contribution.