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Olfactory-based mechanisms have been hypothesized for biological behaviors including foraging, mate-seeking, homing, and host-seeking. Autonomous underwater vehicles (AUVs) capable of such chemical plume tracing feats would have applicability in searching for environmentally interesting phenomena, unexploded ordinance, undersea wreckage, and sources of hazardous chemicals or pollutants. This article presents an approach and experimental results using a REMUS AUV to find a chemical plume, trace the chemical plume to its source, and maneuver to reliably declare the source location. The experimental results are performed using a plume of Rhodamine dye developed in a turbulent, near-shore, oceanic fluid flow. [ABSTRACT FROM AUTHOR]

This paper proposes a novel constitutive model of magnetorheological polishing fluids (MRPFs) to predict field-dependent properties such as yield shear stress. First, the invasion of polishing particles to carbonyl iron particle (CIP) chains is analyzed in terms of the destructive effect on the distance of particles and the enhancement of chain structures. Subsequently, the hexagonal close-packed structure of magnetorheological fluids (MRFs) is utilized to formulate a constitutive model of MRPFs after examining the reconstructed distance and the proportional property of carbonyl iron particle chains affected by the polishing particles. According to the constitutive model, several factors that may affect the performance of MRPFs are considered, and experiments are carried out to prove these conjectures. A series of experiments explore the influencing mechanism of the radius and volume fraction of the polishing particles on the field-dependent properties of MRPFs such as the yield shear stress. The results, which are highly consistent with the simulation data based on constitutive model, show that the radius and volume fraction of polishing particles significantly affect the field-dependent properties of MRPFs. In addition, at a given magnetic field intensity the optimum radius and volume fraction of the polishing particles can be obtained to enhance the field-dependent yield shear stress of MRPFs. [ABSTRACT FROM AUTHOR]

Small-angle x-ray scatter imaging has a high intrinsic contrast in cancer research and other applications, and provides information on molecular composition and micro-structure of the tissue. In general, the implementations of small-angle coherent scatter imaging can be divided into two main categories: direct tomography and angular dispersive computerized tomography. Based on the recent development of energy-discriminative photon-counting detector array, here we propose a computerized tomography setup based on energy-dispersive measurement with a photon-counting detector array. To show merits of the energy-dispersive approach, we have performed numerical tests with a phantom containing various tissue types, in comparison with the existing imaging approaches. The results show that with an energy resolution of ~6 keV, the energy dispersive tomography system with a broadband tabletop x-ray would outperform the angular dispersive system, which makes the x-ray small-angle scatter tomography promising for high-specificity tissue imaging. [ABSTRACT FROM AUTHOR]

In order to explore the relative permeability characteristics of gas-water in the crushed coal rock mass around the drilling hole of gas extraction, the gas-water coupling permeation test system of the crushed rock mass was used to carry out the gas-water coupling permeation test by using the steady-state osmosis method, and the variation characteristics of the coal sample permeability parameters with osmotic pressure and axial pressure were obtained, and the interaction relationship between the permeation parameters was analyzed. The results show that the porosity of the crushed coal mass under pressure shows a rapid decline, a slow decline and stabilization with the increase of axial pressure. With the increase of water saturation, the relative permeability of coal-like gases decreases rapidly, the relative permeability of water increases linearly, the relative permeability of gases and water shows a competitive relationship, and the sensitivity of gas permeability to water saturation is higher. The total permeability of gas and water decreases with the increase of the effective force, obeying the exponential function relationship, the effective force will affect the deformation process of the pore structure of the crushed coal rock mass, and with the decrease of porosity, the effective permeability of the gas decreases and the relative permeability increases. The influence of osmotic pressure on the relative permeability of water and gas can be divided into gas dominant stage, isotonic stage and water dominant stage, and the critical osmotic pressure extraction value ranges from 0.4 MPa to 0.6 MPa.

Background Acute myocardial infarction (AMI) complicated with cardiogenic shock (CS) is a common emergency and severe disease in the department of cardiology. Timely and effective hemodynamic support is one of the important means to save the lives of such patients. Research on intraaortic balloon pumping (IABP) combined with extracorporeal membrane oxygenation (ECMO) had important clinical significance for the efficacy of these patients. Objective To explore the efficacy of IABP combined with ECMO in patients with AMI and CS and the inflencing factor of the need for ECMO support in patients with AMI and CS. Methods A total of 91 patients with AMI and CS treated with IABP in the Coronary Care Unit (CCU ward) of the First Affiliated Hospital of Zhengzhou University from October 2014 to October 2020 were collected and divided into IABP group (n=65) and IABP+ECMO group (n=26) according to the use of ECMO. The clinical data of the patients in both groups were collected and analyzed. The 12-months survival rate of patients discharged from hospital was followed up. The inflecting factors of AMI patients complicated with CS treated with IABP needed ECMO support by Multivariate logistic regression analysis. Results Rate of cardiac arrest after IABP, VIS level at 24 h, survival rate at 12 months after discharge and proportion of continuous renal replacement therapy (CRRT) , tracheal intubation, pulmonary infection, lower extremity ischemia, acute kidney injury and gastrointestinal bleeding, 12-month survival rate after discharge, the use ratio of epinepHrine and norepinepHrine in IABP group were lower than those in IABP+ECMO group (P0.05) . The group and time had significant interaction effects on lactic acid and pH (P0.05) . The main effect of group on systolic blood pressure, diastolic blood pressure, heart rate, lactic acid and pH was not significant (P>0.05) . Systolic blood pressure, pH at 24 h after treatment and 72 h after treatment were higher than that before treatment in both groups (P

Two-photon-excited fluorescence and second-harmonic generation are characterized as a function of laser pulse duration as short as sub-10-fs. A comparative study is performed where pulse duration is varied by introducing dispersion, as reported previously, and by tailoring pulse spectral width and minimizing its time-bandwidth product (transform-limited pulses). Experimental data and calculations show that characterizing a two-photon signal with the two schemes to vary pulse duration measures different phenomena. Two-photon signal characterization using dispersion-broadened pulses measures only the effect of chirp on the pulse two-photon-excitation spectrum and is independent of molecular response. Transform-limited pulses are used to measure the dependence of two-photon signal generation on pulse duration. Calculations show that deviation from the 1Tprelationship would be expected as the transform-limited pulse spectral width approaches the molecular two-photon absorption linewidth and exhibits asymptotic behavior for pulse spectral widths 10 times greater than the absorption linewidth. Experimental measurements are consistent with the predicted behavior. The impact of using ultrashort laser pulses on the performance characteristics of nonlinear optical microscopy is discussed. [ABSTRACT FROM AUTHOR]