Continuous, noninvasive monitoring of total hemoglobin concentration by an optoacoustic technique

Measurement of total hemoglobin concentration [Hgb] is a blood test that is widely used to evaluate outpatients, hospital inpatients, and surgical patients, especially those undergoing surgery associated with extensive blood loss, rapid fluid administration, and transfusion of packed red blood cells. Current techniques for measurement of [Hgb] are invasive (requiring blood sampling) and cannot provide real-time, continuous monitoring. We propose to use an optoacoustic technique for noninvasive and continuous monitoring of [Hgb]. The high resolution of the optoacoustic technique may provide accurate measurement of [Hgb] by detection and analysis of optoacoustic signals induced by short optical pulses in blood circulating in arteries or veins. We designed, built, and tested in vitro (in both tissue phantoms and in preliminary in vivo experiments) a portable optoacoustic system for the monitoring of [Hgb] in the radial artery. The system includes a nanosecond laser operating in the near-infrared spectral range and a sensitive optoacoustic probe designed to irradiate the radial artery through the skin and detect optoacoustic signals induced in blood. Results of our studies demonstrated that (1) the slope of optoacoustic waves induced in blood in the transmission mode is linearly dependent on [Hgb] in the range from 6.2 to 12.4 g/dl, (2) optoacoustic signals can be detected despite optical attenuation in turbid tissue phantoms with a thickness of 1 cm, and (3) the optoacoustic system detects signals induced in blood circulating in the radial artery. These data suggest that the optoacoustic system can be used for accurate, noninvasive, real-time, and continuous monitoring of [Hgb].     

Analysis of Rheological Equations Involving More Than One Fractional Parameters by the Use of the Simplest Mechanical Systems Based on These Equations

The behaviour of rheological models containing more than onefractional derivative or fractional operator of fractional orders areinvestigated. All rheological models discussed can be separated intothree groups depending on magnitudes of the value_*/_* (where_* and _* are the orders ofsenior fractional derivatives of stress and strain, respectively): themodels are thermodynamically admissible only when_*/_* = 1 (the first group),thermodynamically compatible only for_*/_* 1 (the secondgroup) and, finally, thermodynamically well-conditioned both at_*/_* 1 and_*/_* > 1 (the third group).It is shown that, under nonstationary excitations, thebehaviour of the simplest mechanical systems (mechanical oscillators,finite and semi-infinite viscoelastic rods), based on the consideredrheological models, may be different (from the point of view ofthermodynamics) from that of the underlying rheological models. Thus,under impulse excitations, the mechanical models based on rheologicalmodels of the first and second groups become thermodynamicallyadmissible not only at_*/_* = 1 but alsowhen _*/_* < 1(mechanical models of group I), but mechanical models based onrheological models of the third group remain thermodynamicallywell-conditioned at the same magnitudes of rheological parameters as thecorresponding rheological models do (mechanical models of group II). Asthis takes place, group I mechanical models possess diffusion-wavefeatures, that is at_*/_*=1 the stress waves ina semi-infinite rod propagate at a finite speed, and the roots ofcharacteristic equations (for nonstationary vibrations of a mechanicaloscillator or a rod of finite length) as functions of the relaxation orretardation times, behave in a way similar to the characteristicequation roots of rheological models possessing instantaneous elasticity(models of the Maxwell type). When_*/_*<1, the stress wavesin a semi-infinite rod propagate instantaneously at infinitely largespeeds, and the roots of characteristic equations (under nonstationaryvibrations of a mechanical oscillator or a rod of finite length) asfunctions of relaxation times behave in a way similar to thecharacteristic equation roots of rheological models lackinginstantaneous elasticity (models of the Kelvin–Voigt type).Mechanical models from group II possess pure wave or pure diffusionfeatures at all magnitudes of_*/_*.     

Deformation of NiTiCu shape memory single crystals in compression

Single-crystal orientations of NiTi10Cu alloys were studied under incremental, cyclic compression conditions to establish the pseudoelastic and shape memory response of this class of alloys. This material exhibits a two-step transformation involving cubic to orthorhombic martensite (B2 → B19) followed by orthorhombic to monoclinic martensite (B19 → B19′). The transformation parameters (shear magnitudes and directions for habit and twin planes) were determined associated with the B2 → B19 transformation. The growth of monoclinic martensite correspondent variant pairs (CVPs) emanating from the orthorhombic structure was also analyzed. The transformation strain for the B2 → B19 case was orientation dependent and lower than the B19 → B19′ transformation in compression for all orientations except those near the [001] pole. The experimental results show that the critical transformation stress is orientation dependent and is in the range 30 to 58 MPa. Orientations that exhibit lower transformation stress (or high resolved shear stress factors, [100] and [012]) produce higher recoverable strains (as high as 4 pct), while other orientations ([011], [111], and [123]) with lower resolved shear stress factors result in recoverable strains less than 3 pct. At higher strains, inelastic deformation develops, limiting recoverability. The recoverable strains are lower than the theoretical values for two main reasons: the transformation is curtailed first by austenite slip and subsequently by martensite slip, and the orthorhombic structure does not fully transform to the monoclinic martensite.     

Analysis of residual stresses in a long hollow cylinder

This paper presents an analytical method for solving the axisymmetric stress problem for a long hollow cylinder subjected to locally-distributed residual (incompatible) strains. This method is based on direct integration of the equilibrium and compatibility equations, which thereby have been reduced to the set of two governing equations for two key functions with corresponding boundary and integral conditions. The governing equations were solved by making use of the Fourier integral transformation. Application of the method is illustrated with an analysis of the welding residual stresses in a butt-welded thick-walled pipe.     

Fast bias‐constrained optimal FIR filtering for time‐invariant state space models

This paper combines the finite impulse response filtering with the Kalman structure (predictor/corrector) and proposes a fast iterative bias‐constrained optimal finite impulse response filtering algorithm for linear discrete time‐invariant models. In order to provide filtering without any requirement of the initial state, the property of unbiasedness is employed. We first derive the optimal finite impulse response filter constrained by unbiasedness in the batch form and then find its fast iterative form for finite‐horizon and full‐horizon computations. The corresponding mean square error is also given in the batch and iterative forms. Extensive simulations are provided to investigate the trade‐off with the Kalman filter. We show that the proposed algorithm has much higher immunity against errors in the noise covariances and better robustness against temporary model uncertainties. The full‐horizon filter operates almost as fast as the Kalman filter, and its estimate converges with time to the Kalman estimate. Copyright © 2016 John Wiley & Sons, Ltd.     

Formation and properties of sediments in constructed wetlands for treatment of domestic wastewater

Sediments formation and biogeochemical properties were studied in an experimental constructed wetland site in Ukraine (“Bioplato”) for treatment of domestic effluents. The wetland, with a capacity of 50 m³ d^? 1 of wastewater, consists of vertical and horizontal filtrations units with fine gravel, middle and coarse sand, a subsurface flow unit with natural wetland soil applied, and a septic tank and sludge-drying field. Macrophytes, reed (Phragmites australis), cattail (Typha latifolia) and a number of sedge species (Carex spp.) were planted in the area and dominate the average cover of 85–90%. Treatment efficiency for BOD₅ and suspended solids was 93–96%, for COD – 82%, for nutrients – 27–50%, and for pathogenic microorganisms 99.3–99.6%. Sludge was sampled at each unit followed by standard laboratory analyses of its main characteristics: total organic carbon (TOC), total nutrients (N, P), contents of trace elements, abundance of pathogenic microorganisms, and general toxicity. Results confirmed that the top layer of sludge from each unit of wetland could be used as a source of fertilizers for grain and leguminous crops.     

Ignition of aluminum-rich Al-Ti mechanical alloys in air

Ignition of metastable Al-Ti mechanical alloys with titanium concentrations from 10 to 25 at% was investigated experimentally. A thin layer of powder was coated on an electrically heated filament. The ignition instant was identified from the powder's radiation measured in real time. Simultaneously, filament temperatures were measured using a high-speed infrared pyrometer to determine the ignition temperature. The experiments were conducted at different filament heating rates in the range of 3×¹⁰³-2×¹⁰⁴ K/s to determine the ignition kinetics. The ignition temperatures and kinetics were compared to the respective characteristics of the phase changes and oxidation steps observed for the same mechanical alloys using thermal analysis. It was shown that at the heating rates exceeding ¹⁰³ K/s, the exothermic formation of a metastable L1₂ phase of Al₃Ti occurring during heating of the Al-Ti mechanical alloys triggers their ignition. This conclusion was confirmed by additional ignition experiments in which annealed mechanical alloys already containing this transition Al₃Ti phase did not ignite in the same temperature range as fresh mechanical alloys. The ignition kinetics identified for Al-Ti mechanical alloys based on thermal analysis and on ignition experiments enables one to predict ignition temperatures as a function of both composition and heating rate. Specifically, extrapolation is possible to higher heating rates typical for aerosol flames.     

Decamethylosmocene-catalyzed efficient oxidation of saturated and aromatic hydrocarbons and alcohols with hydrogen peroxide in the presence of pyridine

Decamethylosmocene, (Me₅C₅)₂Os (1), is a pre-catalyst in a very efficient oxidation of alkanes with hydrogen peroxide in acetonitrile at 20–60 °C. The reaction proceeds with a substantial lag period that can be reduced by the addition of pyridine in a small concentration. The lag period can be removed if 1 is incubated with pyridine and/or H₂O₂ in MeCN prior to the alkane oxidation. Alkanes, RH, are oxidized primarily to the corresponding alkyl hydroperoxides, ROOH. Turnover numbers attain 51,000 in the case of cyclohexane (maximum turnover frequency was 6000 h^?1) and 3600 in the case of ethane. The oxidation of benzene and styrene also occurs with a lag period to afford phenol and benzaldehyde, respectively. A kinetic study of cyclohexane oxidation and selectivity parameters (measured in the oxidation of n-heptane, methylcyclohexane, isooctane, cis- and trans-dimethylcyclohexanes) indicates that the oxidation of saturated, olefinic, and aromatic hydrocarbons proceeds with the participation of hydroxyl radicals. The 1/H₂O₂/py/MeCN system also oxidizes 1-phenylethanol to acetophenone.