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1
Hallbach, Jɒrgen, Georg E. Hoffmann, and Walter G. Guder. "Overestimation of albumin in heparinized plasma." Clinical Chemistry 37, no. 4 (1991): 566–68. http://dx.doi.org/10.1093/clinchem/37.4.566.
Testo completoAbstract (sommario):
Abstract Monochromatic measurement of albumin by the bromcresol green method leads to overestimation of albumin in the presence of heparin. The interference seems to be caused by fibrinogen, which, in the presence of heparin, produces an almost constant increase of the measuring signal over the whole range of suitable wavelengths (550 to 700 nm). The albumin overestimation can be eliminated by using a bichromatic modification. An application of this procedure for the automated analyzer RAXT, RA-1000 (Bayer Diagnostik, Technicon) is presented. We recommend using only bichromatic methods for albumin determination with bromcresol green to avoid unexpected analytical artifacts.
2
Williams, M. R., F. Chi, M. T. Cashen, and H. Metcalf. "Measurement of the bichromatic optical force on Rb atoms." Physical Review A 60, no. 3 (1999): R1763—R1766. http://dx.doi.org/10.1103/physreva.60.r1763.
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Li, Wei, Xudong Yu, and Jing Zhang. "Measurement of the squeezed vacuum state by a bichromatic local oscillator." Optics Letters 40, no. 22 (2015): 5299. http://dx.doi.org/10.1364/ol.40.005299.
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Baker, J., P. Metcalf, M. Tatnell, M. Lever, and R. Johnson. "Quality assessment of determinations of serum fructosamine in 33 clinical chemistry laboratories." Clinical Chemistry 32, no. 12 (1986): 2133–36. http://dx.doi.org/10.1093/clinchem/32.12.2133.
Testo completoAbstract (sommario):
Abstract We investigated the analytical performance of fructosamine measurement in 33 routine clinical chemistry laboratories. We prepared 12 human control sera spanning a range of nondiabetic and diabetic fructosamine concentrations and assigned target values by using commercial reagents and a Cobas Bio centrifugal analyzer. Each control serum was analyzed by participating laboratories on two separate occasions. Averaged results were compared with target values, and systematic error was determined from slope and intercept regression coefficients. Overall, we found no significant (p greater than 0.05) slope or intercept bias, although slight nonlinearity was found with bichromatic instruments. Random error was determined from the standard error of estimate and from duplicate measurements. We found a median interlaboratory CV of 5.36% and similar analytical performance with all automated instruments used. The median random error with manual techniques was 18.1%. We conclude that fructosamine measurement as currently performed in routine laboratories is sufficiently accurate and reliable to function as an index of blood glucose control in diabetic patients.
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Thiermann, V., and H. Grassl. "The measurement of turbulent surface-layer fluxes by use of bichromatic scintillation." Boundary-Layer Meteorology 58, no. 4 (1992): 367–89. http://dx.doi.org/10.1007/bf00120238.
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Sampson, M., M. Ruddel, and R. J. Elin. "Effects of specimen turbidity and glycerol concentration on nine enzymatic methods for triglyceride determination." Clinical Chemistry 40, no. 2 (1994): 221–26. http://dx.doi.org/10.1093/clinchem/40.2.221.
Testo completoAbstract (sommario):
Abstract We compared the effects of specimen turbidity and glycerol concentration on nine enzymatic methods for triglyceride measurement. We assayed 51 specimens with triglyceride concentrations of 0.85-8.21 mmol/L (75-727 mg/dL) and turbidity at 420 nm equivalent to > or = 0.1 mmol/L (8.8 mg/dL) triglyceride (measured as part of our comparison method). The data were analyzed by multiple regression, which gave coefficients for the effects of glycerol concentration and the change in turbidity during the reaction. The effects of specimen turbidity and glycerol concentration were method-dependent and ranged from 6.20% to -15.67% of the measured result. The magnitude of the turbidity effect (in assays with a significant turbidity interference) was similar to that for glycerol (in assays with a significant glycerol interference). A triglyceride assay with a bichromatic measurement was less subject to interference from turbidity.
7
Barbour, H. M., and W. Davidson. "Studies on measurement of plasma magnesium: application of the Magon dye method to the "Monarch" centrifugal analyzer." Clinical Chemistry 34, no. 10 (1988): 2103–5. http://dx.doi.org/10.1093/clinchem/34.10.2103.
Testo completoAbstract (sommario):
Abstract The "Magnesium Liquid Stable Reagent Set" from Medical Analysis Systems, Inc., is evaluated. The method, which involves Magon dye binding and bichromatic absorbance measurements, was used in a Monarch centrifugal analyzer. Results were compared with those by atomic absorption spectrometry. The calibration curve for the Magon method is linear to 2.5 mmol/L, with a 2-microL sample volume. Analytical recovery of magnesium added to human plasma ranged from 95 to 102%. The working reagent is stable for at least five days at 15 degrees C. At concentrations of 0.54 and 1.20 mmol/L, the respective CVs were 2.15 and 3.60% within batch, and 3.13 and 3.24% between batch. We analyzed 150 clinical samples for magnesium by both methods. Absorbance readings at 520/600 nm rather than 520/690 nm improved the correlation (r = 0.9777 and r = 0.9428, respectively). Calcium, albumin, phosphate, or bilirubin did not significantly interfere.
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Diehl, Brett, Alberto Castro, Lars Jaquemetton, and Darren Beckett. "Thermal Calibration of Ratiometric, On-Axis Melt Pool Monitoring Photodetector System Using Tungsten Strip Lamp." Materials Evaluation 80, no. 4 (2022): 64–73. http://dx.doi.org/10.32548/2022.me-04271.
Testo completoAbstract (sommario):
In situ melt pool monitoring is a set of technologies widely deployed on industrial, metals-based laser powder bed fusion (LPBF) additive manufacturing (AM) systems. This study investigates the use of a calibrated tungsten ribbon lamp as a reference standard to calibrate a photodetector based, on-axis melt pool monitoring system. Calibration demonstrates two functions: (a) enable a reference for measuring and ensuring system repeatability, and (b) enable reference to physical temperature values based on the measured photodetector signals. The second function is explored in this paper. A regression-based model is derived based on bichromatic Planck thermometry theory. The calibrated tungsten lamp is then placed within a LPBF system, and resulting photodetector signals are measured at different lamp temperature set points to calibrate the model. Finally, several additional characterization tests and their results are presented verifying the temporal response of the lamp, measurement noise as a function of sampling time, and spectroscopic measurements of the LPBF optics and their potential effect on temperature calibration. A framework is also developed to normalize temperature readings across the build plate to remove location-dependent optical artifacts.
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Yang, Lei, Bao Wang, and Hao Xiong. "Generation of Second-Order Sideband through Nonlinear Magnetostrictive Interaction." Photonics 10, no. 8 (2023): 886. http://dx.doi.org/10.3390/photonics10080886.
Testo completoAbstract (sommario):
Nonlinear interaction between the magnon mode and the mechanical mode in a magnomechanical system is treated analytically where the magnon mode is coherently driven by a bichromatic microwave drive field consisting of a strong pumping field and a weak probe field and that works within a perturbative regime. Using experimentally achievable parameters, we show that the magnonic second-order sideband is generated and can be considerably enhanced by increasing the power of the pumping field. The suppression of the magnonic second-order sideband generation at the resonance point is discussed. Furthermore, the efficiency of magnonic second-order sideband generation can be well controlled by adjusting the applied bias magnetic field strength, which is a particular feature compared to the optical second-order sideband. In addition to offering insights into the magnomechanical nonlinearity, the present results have the potential to pave the way for exploring practical applications for achieving high-precision measurement in magnonics.
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Jegou, Loïc, Joel Lachambre, Nicolas Tardif, et al. "Bichromatic melt pool thermal measurement based on a Red, Green, and Blue camera: Application to additive manufacturing processes." Optics & Laser Technology 167 (December 2023): 109799. http://dx.doi.org/10.1016/j.optlastec.2023.109799.
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Lott, J. A., and B. T. Doumas. ""Direct" and total bilirubin tests: contemporary problems." Clinical Chemistry 39, no. 4 (1993): 641–47. http://dx.doi.org/10.1093/clinchem/39.4.641.
Testo completoAbstract (sommario):
Abstract In eight unique challenges mailed by The College of American Pathologists Comprehensive Chemistry Survey to participating laboratories within 3 years, results for direct-reacting bilirubin (DBIL) were highly variable among the 12 largest peer groups, and most of the results differed greatly from the values obtained by a referred method. Peer-group mean values for total bilirubin (TBIL) were in much better agreement with each other and with those obtained by the Reference Method for TBIL. From a review of the information on the assay of DBIL provided to us by the manufacturers, we conclude that among the major causes of the large variability and bias in DBIL assays are problems with calibration, lack of a serum blank measurement, inadequate concentrations of HCl in the reaction mixture, inappropriate use of bichromatic correction methods, and possibly the use of wetting agents or surfactants in the reagent. Within-group SDs were small and generally acceptable. The among-peer-group variability in DBIL values is attributable to bias, not imprecision. We recommend several simple changes that could improve the accuracy of DBIL determinations in clinical laboratories.
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Li, Guoyao, and Zhang-Qi Yin. "Squeezing Light via Levitated Cavity Optomechanics." Photonics 9, no. 2 (2022): 57. http://dx.doi.org/10.3390/photonics9020057.
Testo completoAbstract (sommario):
Squeezing light is a critical resource in both fundamental physics and precision measurement. Squeezing light has been generated through optical-parametric amplification inside an optical resonator. However, preparing the squeezing light in an optomechanical system is still a challenge for the thermal noise inevitably coupled to the system. We consider an optically levitated nano-particle in a bichromatic cavity, in which two cavity modes could be excited by the scattering photons of the dual tweezers, respectively. Based on the coherent scattering mechanism, the ultra-strong coupling between the cavity field and the torsional motion of nano-particle could be achieved for the current experimental conditions. With the back-action of the optically levitated nano-particle, the broad single-mode squeezing light can be realized in the bad cavity regime. Even at room temperature, the single-mode light can be squeezed for more than 17 dB, which is far beyond the 3 dB limit. The two-mode squeezing light can also be generated, if the optical tweezers contain two frequencies, one is on the red sideband of the cavity mode, the other is on the blue sideband. The two-mode squeezing can be maximized near the boundary of the system stable regime and is sensitive to both the cavity decay rate and the power of the optical tweezers.
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Jorge, Vinicius Lemes, Issam Bendaoud, Fabien Soulié, and Cyril Bordreuil. "Rear Weld Pool Thermal Monitoring in GTAW Process Using a Developed Two-Colour Pyrometer." Metals 14, no. 8 (2024): 937. http://dx.doi.org/10.3390/met14080937.
Testo completoAbstract (sommario):
New systems and methods to access the temperature of the melt pool in welding processes have been developed to study phenomena, monitor behaviours, and even be used in closed-loop control strategies. Concerning arc welding processes, the arc radiation might impose a challenge to measure the temperature. However, heat input is the key point for welding quality. This work aims to evaluate the feasibility and detect potentialities of accessing the thermal field from the rear weld pool in the GTAW process by using in-house developed equipment. The original system was conceptualized based on a previous bichromatic method. Experiments were carried out with and without the wire feed addition, and welding parameters were varied to explore its impacts on the temperature measurement. A strategy to select the regions of interest (ROIs) within the weld pool was created, and the mean temperature was calculated and correlated to the weld bead features. This strategy was able to overcome the challenges imposed by the electrode/nozzle reflection and the arc radiation during the welding. The rear weld pool thermal field was shown to be an important source of data to provide hints of the weld bead features. The mean temperature can indicate geometrical changes in the weld bead. Furthermore, the technique has the potential to be used as a promising real-time process monitoring tool.
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McNeill, Donald H. "Bichromator for electron density measurements." Review of Scientific Instruments 73, no. 9 (2002): 3193–97. http://dx.doi.org/10.1063/1.1499543.
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De Souza e Silva, Mario G., Nils Kerpen, Paulo Cesar C. Rosman, Torsten Schlurmann, and Claudio F. Neves. "FINDING BICHROMATIC-BIDIRECTIONAL WAVES WITH ADVs." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 33. http://dx.doi.org/10.9753/icce.v36.papers.33.
Testo completoAbstract (sommario):
The aim of this study is to investigate Bichromatic-Bidirectional waves to characterize the subtractive wave-wave nonlinear interactions, using adaptive techniques rather than traditional spectral techniques. A physical model test in a 3D-wave basin was conducted and measurements were made with two arrays of ultrasonic sensors of free surface and one array of ADVs. The Hilbert-Huang transform, aided by the Multivariate Empirical Mode Decomposition, was applied to the orbital velocity data and the main characteristics of the infragravity wave (velocity amplitude, period and direction) were extracted with a good precision.
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Silva, Mario G. Souza e., Ricardo Guimarães, Nils Kerpen, Paulo Cesar Rosman, Claudio F. Neves, and Torsten Schlurmann. "ORBITAL VELOCITIES DUE TO BICHROMATIC-BIDIRECTIONAL WAVES." Coastal Engineering Proceedings, no. 37 (September 1, 2023): 59. http://dx.doi.org/10.9753/icce.v37.papers.59.
Testo completoAbstract (sommario):
The paper describes the orbital velocity pattern generated by Bichromatic-Bidirectional waves (Bi-Bi waves), and investigate how the forced (long period) wave decays along the depth. Experiments conducted at a wave basin proved that the use of ADVs provided much better results than free surface elevations, due to the higher sensitivity of the instrument, as compared of the free surface measurements.
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Sofieva, Viktoria F., Francis Dalaudier, Alain Hauchecorne, and Valery Kan. "High-resolution temperature profiles retrieved from bichromatic stellar scintillation measurements by GOMOS/Envisat." Atmospheric Measurement Techniques 12, no. 1 (2019): 585–98. http://dx.doi.org/10.5194/amt-12-585-2019.
Testo completoAbstract (sommario):
Abstract. In this paper, we describe the inversion algorithm for retrievals of high vertical resolution temperature profiles (HRTPs) using bichromatic stellar scintillation measurements in the occultation geometry. This retrieval algorithm has been improved with respect to nominal ESA processing and applied to the measurements by Global Ozone Monitoring by Occultation of Stars (GOMOS) operated on board Envisat in 2002–2012. The retrieval method exploits the chromatic refraction in the Earth's atmosphere. The bichromatic scintillations allow the determination of the refractive angle, which is proportional to the time delay between the photometer signals. The paper discusses the basic principle and detailed inversion algorithm for reconstruction of high-resolution density, pressure and temperature profiles in the stratosphere from scintillation measurements. The HRTPs are retrieved with a very good vertical resolution of ∼200 m and high precision (random uncertainty) of ∼1–3 K for altitudes of 15–32 km and with a global coverage. The best accuracy is achieved for in-orbital-plane occultations, and the precision weakly depends on star brightness. The whole GOMOS dataset has been processed with the improved HRTP inversion algorithm using the FMI's scientific processor; and the dataset (HRTP FSP v1) is in open access. The validation of small-scale fluctuations in the retrieved HRTPs is performed via comparison of vertical wavenumber spectra of temperature fluctuations in HRTPs and in collocated radiosonde data. We found that the spectral features of temperature fluctuations are very similar in HRTPs and collocated radiosonde temperature profiles. HRTPs can be assimilated into atmospheric models, used in studies of stratospheric clouds and used for the analysis of internal gravity waves' activity. As an example of geophysical applications, gravity wave potential energy has been estimated using the HRTP dataset. The obtained spatiotemporal distributions of gravity wave energy are in good agreement with the previous analyses using other measurements.
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Rijnsdorp, Dirk Pieter, Pieter Bart Smit, and Marcel Zijlema. "NON-HYDROSTATIC MODELLING OF INFRAGRAVITY WAVES USING SWASH." Coastal Engineering Proceedings 1, no. 33 (2012): 27. http://dx.doi.org/10.9753/icce.v33.currents.27.
Testo completoAbstract (sommario):
This paper presents numerical modelling of the nearshore transformation of infragravity waves induced by bichromatic wave groups over a horizontal and a sloping bottom. The non-hydrostatic model SWASH is assessed by comparing model predictions with analytical solutions over a horizontal bottom and with detailed laboratory observations for a sloping bottom. Good agreement between model predictions and data is found throughout the domain for bound infragravity waves. Furthermore the model predicts greater outgoing free infragravity wave-heights for steeper slope regimes which is consistent with the measurements. The model however tends to overestimate the magnitude of the outgoing infragravity waves.
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Andersen, Thomas Lykke, Maria Clavero, Mads Røge Eldrup, Peter Frigaard, and Miguel Losada. "ACTIVE ABSORPTION OF NONLINEAR IRREGULAR WAVES." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 12. http://dx.doi.org/10.9753/icce.v36.papers.12.
Testo completoAbstract (sommario):
In the present paper, the performance of active absorption systems based on nearfield surface elevation measurements is studied. Based on linear wavemaker theory the performance of such systems can easily be calculated for linear waves. A recent study demonstrated that bound superharmonics in regular waves is also well absorbed by such system and has a re-reflection similar to a linear component. However, the performance of active absorption systems on nonlinear irregular waves has never been studied. In the present paper the absorption of bound sub and superharmonics in bichromatic and irregular waves is examined based on new model tests. The conclusion is that also in irregular waves the bound harmonics are well absorbed by the studied active absorption system.
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Zang, J., R. Gibson, P. H. Taylor, R. Eatock Taylor, and C. Swan. "Second Order Wave Diffraction Around a Fixed Ship-Shaped Body in Unidirectional Steep Waves." Journal of Offshore Mechanics and Arctic Engineering 128, no. 2 (2006): 89–99. http://dx.doi.org/10.1115/1.2185130.
Testo completoAbstract (sommario):
The objective of this research, part of the EU FP5 REBASDO Program, is to examine the effects of second order wave diffraction in wave run-up around the bow of a vessel (FPSO) in random seas. In this work, the nonlinear wave scattering problem is solved by employing a quadratic boundary element method. A computer program, DIFFRACT, has been developed and recently extended to deal with unidirectional and directional bichromatic input wave systems, calculating second order wave diffraction loads and free surface elevation under regular waves and focused wave groups. The second order wave interaction with a vessel in a unidirectional focused wave group is presented in this paper. Comparison of numerical results and experimental measurements conducted at Imperial College shows excellent agreement. The second order free surface components at the bow of the ship are very significant, and cannot be neglected if one requires accurate prediction of the wave-structure interaction; otherwise a major underestimation of the wave impact on the structure could occur.
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Lamien, B., T. Pierre, H. R. B. Orlande, et al. "Sequential estimation of high temperatures of liquid metals by using particle filter methods." High Temperatures-High Pressures 53, no. 1-2 (2024): 89–111. http://dx.doi.org/10.32908/hthp.v53.jsf01.
Testo completoAbstract (sommario):
This work follows up our previous studies dedicated to the estimation of the transient temperature of niobium and 100c6 steel samples, in ranges that include solid and liquid phases, as well as phase changes. In the experimental setup, a metallic sample of few millimeters is aerodynamically levitated and then heated by a powerful laser, while a collimator focused on the sample collects the radiative flux that is split towards five pyrometers of different wavelengths. The measured spectral fluxes are used in an inverse analysis to estimate the sample temperature. Difficulties in the inverse problem solution related to the dependence of the sample emittance with temperature and wavelength could be overcome by reducing the number of model parameters using a simple linear variation of the emittance with respect to the wavelength. In this work the transient temperature of the sample is estimated sequentially by solving a state estimation problem with two algorithms of the particle filter method, namely: the Sampling Importance Resampling (SIR) and Auxiliary Sampling Importance Resampling (ASIR) algorithms. Results obtained with these algorithms and the radiative spectral fluxes exhibited small discrepancies with respect to the temperature measurements of a reference bichromatic pyrometer.
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Berni, C., H. Michallet, and E. Barthélemy. "Effects of horizontal pressure gradients on bed destabilization under waves." Journal of Fluid Mechanics 812 (January 5, 2017): 721–51. http://dx.doi.org/10.1017/jfm.2016.805.
Testo completoAbstract (sommario):
We report on new experiments designed to investigate bed destabilization processes in a two-dimensional wave flume physical model of a beach. The mobile bed consists of non-cohesive granular material of low density. The wave conditions are provided by repeating a cycle of waves made of two bichromatic groups of different period. The horizontal and vertical velocities are acoustically profiled vertically from free-stream elevation down to the still bed level in the surf zone. Additional measurements of the fluid pressure at positions closely aligned horizontally and vertically in and slightly above the sediment bed are undertaken. Mobile bed interfaces, still bed and top interface, are detected via acoustic and optical methods. Both methods are cross-compared and give similar results. Flow turbulence over the bed is analysed, the Reynolds turbulent shear stress is found negligible compared to the orbital flow induced momentum diffusion. The shear stress and the horizontal pressure gradient are computed at near-bed elevation and used in the bed incipient plug flow model of Sleath (Cont. Shelf Res., vol. 19 (13), 1999, pp. 1643–1664). Both the model and the measurements confirm that destabilization occurs when the non-dimensional pressure gradient (or Sleath number) exceeds the threshold value of 0.3 which is simultaneous with strong flow acceleration. The near-bottom fluid shear stress detected during these flow accelerations at steep wave fronts is found experimentally to be negative, which is retrieved with an unsteady plug flow model. This is suggesting that the fluid above the bed resists the sediment layer motion at these particular phases.
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Vujakovic, Aleksandra, Aleksandra Dakovic, Jovan Lemic, Ana Radosavljevic-Mihajlovic, and Magdalena Tomasevic-Canovic. "Adsorption of inorganic anionic contaminants on surfactant modified minerals." Journal of the Serbian Chemical Society 68, no. 11 (2003): 833–41. http://dx.doi.org/10.2298/jsc0311833v.
Testo completoAbstract (sommario):
Organo-mineral complexes were obtained by treatment of aluminosilicate minerals (zeolite, bentonite and diatomaceous earth) with a primary amine (oleylamine) and an alkyl ammonium salt (stearyldimethylbenzyl ammonium chloride). The modification of the zeolite surface was carried out in two steps. The first step was treatment of the zeolite with 2M HCl. This acid treatment of the zeolite increased its affinity for neutral molecules such as surface-active amines. The second step of the modification was the adsorption of oleylamine on the acid treated zeolite. Four types of organo-mineral complexes were prepared and their anion adsorption properties were compared to those of organo-zeolite. The adsorption of sulphate bichromate and dihydrogenphosphate anions on the organo-mineral complexes was investigated. The anion adsorption measurements showed that the most efficient adsorbent for anion water pollutants was the primary amine modified H+-form zeolite.
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Delwiche, Stephen R., Thomas C. Pearson, and Daniel L. Brabec. "High-Speed Optical Sorting of Soft Wheat for Reduction of Deoxynivalenol." Plant Disease 89, no. 11 (2005): 1214–19. http://dx.doi.org/10.1094/pd-89-1214.
Testo completoAbstract (sommario):
Fusarium head blight (FHB) is a fungal disease that affects small cereal grains, such as wheat and barley, and is becoming more prevalent throughout much of the world's temperate climates. The disease poses a health risk to humans and livestock because of the associated production of the mycotoxin deoxynivalenol (DON or vomitoxin) by the causal organism, Fusarium graminearum. A study was undertaken to examine the efficiency of high-speed, optical sorting of intact wheat (Triticum aestivum) kernels for reduction of DON concentration. Soft red winter (n = 32) and soft white (n = 3) wheat samples, known to have elevated levels of FHB, were obtained from commercial mills throughout the eastern United States. An additional seven samples of wheat from the discard piles of in-mill cleaners were also studied. Fusarium-damaged wheat, cleaned of nonkernels and foreign material ( ~4.5 kg/sample, DON range = 0.6 to 20 mg/kg), was fed into a commercial high-speed bichromatic sorter operating at a throughput of 0.33 kg/(channel-min) and a kernel rejection rate of 10%. A wavelength filter pair combination of 675 and 1,480 nm was selected for sorting, based on prior research. Visual measurements of the proportion of Fusarium-damaged kernels were collected on incoming and sorted seed (separate analyses of accepted and rejected portions), as were measurements of DON concentration. Results indicated that the fraction of DON contaminant level in the sorted wheat to that in the unsorted wheat ranged from 18 to 112%, with an average of 51%. Nine of the 35 regular samples and all seven of the discard pile samples underwent a second sort, with five from this second set undergoing a third sort. Multiple sorting was effective in producing wheat whose DON concentration was between 16 and 69% of its original, unsorted value.
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Ward, H. C., J. G. Evans, C. S. B. Grimmond, and J. Bradford. "Infrared and millimetre-wave scintillometry in the suburban environment – Part 1: Structure parameters." Atmospheric Measurement Techniques Discussions 7, no. 11 (2014): 11169–220. http://dx.doi.org/10.5194/amtd-7-11169-2014.
Testo completoAbstract (sommario):
Abstract. Scintillometry, a form of ground-based remote sensing, provides the capability to estimate surface heat fluxes over scales of a few hundred metres to kilometres. Measurements are spatial averages, making this technique particularly valuable over areas with moderate heterogeneity such as mixed agricultural or urban environments. In this study, we present the structure parameters of temperature and humidity, which can be related to the sensible and latent heat fluxes through similarity theory, for a suburban area in the UK. The fluxes are provided in the second paper of this two-part series. A unique millimetre-wave scintillometer was combined with an infrared scintillometer along a 5.5 km path over northern Swindon. The pairing of these two wavelengths offers sensitivity to both temperature and humidity fluctuations and the so-called "bichromatic-correlation" method is also used to retrieve the path-averaged temperature-humidity correlation. Comparison is made with structure parameters calculated from an eddy covariance station located close to the centre of the scintillometer path. The performance of the techniques under different conditions is discussed. Similar behaviour is seen between the two datasets at sub-daily timescales. For the two summer-to-winter periods presented here, similar evolution is displayed across the seasons. A higher vegetation fraction within the scintillometer source area is consistent with the lower Bowen ratio observed (midday Bowen ratio < 1) compared with more built-up areas around the eddy covariance station. The energy partitioning is further explored in the copanion paper.
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Vrecica, Teodor, and Yaron Toledo. "Consistent nonlinear stochastic evolution equations for deep to shallow water wave shoaling." Journal of Fluid Mechanics 794 (April 4, 2016): 310–42. http://dx.doi.org/10.1017/jfm.2015.750.
Testo completoAbstract (sommario):
Nonlinear interactions between sea waves and the sea bottom are a major mechanism for energy transfer between the different wave frequencies in the near-shore region. Nevertheless, it is difficult to account for this phenomenon in stochastic wave forecasting models due to its mathematical complexity, which mostly consists of computing either the bispectral evolution or non-local shoaling coefficients. In this work, quasi-two-dimensional stochastic energy evolution equations are derived for dispersive water waves up to quadratic nonlinearity. The bispectral evolution equations are formulated using stochastic closure. They are solved analytically and substituted into the energy evolution equations to construct a stochastic model with non-local shoaling coefficients, which includes nonlinear dissipative effects and slow time evolution. The nonlinear shoaling mechanism is investigated and shown to present two different behaviour types. The first consists of a rapidly oscillating behaviour transferring energy back and forth between wave harmonics in deep water. Owing to the contribution of bottom components for closing the class III Bragg resonance conditions, this behaviour includes mean energy transfer when waves reach intermediate water depths. The second behaviour relates to one-dimensional shoaling effects in shallow water depths. In contrast to the behaviour in intermediate water depths, it is shown that the nonlinear shoaling coefficients refrain from their oscillatory nature while presenting an exponential energy transfer. This is explained through the one-dimensional satisfaction of the Bragg resonance conditions by wave triads due to the non-dispersive propagation in this region even without depth changes. The energy evolution model is localized using a matching approach to account for both these behaviour types. The model is evaluated with respect to deterministic ensembles, field measurements and laboratory experiments while performing well in modelling monochromatic superharmonic self-interactions and infra-gravity wave generation from bichromatic waves and a realistic wave spectrum evolution. This lays physical and mathematical grounds for the validity of unexplained simplifications in former works and the capability to construct a formulation that consistently accounts for nonlinear energy transfers from deep to shallow water.
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Afinogenova, A. G., T. M. Voroshilova, G. E. Afinogenov, D. Yu Maday, and A. A. Spiridonova. "TIME-KILL ASSAY: AN EFFICACY OF SYNERGY BETWEEN CARBAPENEMS AND CLODRONIC ACID." Russian Journal of Infection and Immunity 8, no. 4 (2019): 497–502. http://dx.doi.org/10.15789/2220-7619-2018-4-497-502.
Testo completoAbstract (sommario):
Abstract. Currently, a search for augmenting antibiotics activity is still crucial due to elevated frequency of detecting carbapenem-resistant Gran-positive bacterial isolates. To resolve this, it might be reasonable to combine carbapenems metal-â-lactamase (MâL) inhibitors. Unfortunately, no MâL inhibitors approved for treatment of carbapenem-resistant infections are currently available. Pathogenic bacteria may survive antibiotic attack, exert tolerance and persistence accompanied with the ongoing infectious process. In connection with this, determining dependence between antimicrobialrelated bactericidal effect and exposure time on microbes at 4, 8, 12 and 24 hours after the onset, a so called time-kill assay, is necessary. A synergy between both agents was noted upon reduced microbial population by ≥ 3 log10. A checkerboard array followed by seeding the microplate well contents onto a dense nutrient medium at various time points were used to assess a synergistic efficacy of carbapenems applied together with clodronic acid against MâL-producing VIMgenotype P. aeruginosa 532/14 clinical isolate obtained from patients with infectious complications (minimal inhibitory concentrations [MIC] for imipenem or meropenem were 512 μg/ml), microbial burden 106 CFU/ml. Optical density was measured at two wavelengths (490 and 630 nm) in ELx800 reader, within 4–24 hour exposure time to determine time of logarithmic growth phase emerging in test culture. It is noteworthy that magnitude of optical density is a difference between two bichromatic measurements resulting in remarkably reduced inaccuracy due to scratches or fingerprints left on the plate. It was found that clodronic acid exhibited a synergic bactericidal effect with carbapenems against a clinically resistant MâL-producing VIM-genotype P. aeruginosa 532/14 strain. Upon that, imipenem-related antimicrobial activity was evident as early as 8 hours after the onset decreasing cell growth down to 1.4 log10 compared to control, whereas 12 hours later it resulted in total inhibition of test strain by decreasing growth of the test strain by 6 log10. Meropenem in combination with clodronic acid showed a more pronounced activity: complete absence of P. aeruginosa 532/14 growth by 8 hours of incubation, growth suppression by 3.2 log10, which reached 6 log10 12–24 hours after the onset. Time-kill assay allows to identify efficient combinations of carbapenems and MâL inhibitors, which is of great importance for increasing therapeutic efficacy of patients with severe purulent-septic complications.
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Ma, Yuxiang, Guohai Dong, and Xiaozhou Ma. "SEPARATION OF LOW-FREQUENCY WAVES BY AN ANALYTICAL METHOD." Coastal Engineering Proceedings 1, no. 32 (2011): 64. http://dx.doi.org/10.9753/icce.v32.waves.64.
Testo completoAbstract (sommario):
A new method for separating low-frequency waves in time domain is proposed by constructing the analytical signals of the measured waves. Using three simultaneous wave records, the time series of incident bound, free and reflected low-frequency waves can be obtained by the present method. This method is only suitable for separating monochromatic low-frequency waves. The applicability of the method is examined by numerical tests. The results show that the present method can give accurate results over sloping beaches when water depth (kh) is larger than 0.2. Then, the present method is used to study an experiment of low-frequency waves over a mild slope beach.
 
 
 References
 
 Bakkenes, H.J. 2002. Observation and separation of bound and free low-frequency waves in the nearshore zone, in Faculty of Civil Engineering and Geosciences. Delft University of Technology: Delft.
 
 Baldock, T.E., D.A., Huntley, P.A.D., Bird, T.O., Hare, and G.N., Bullock. 2000. Breakpoint generated surf beat induced by bichromatic wave groups. Coastal Engineering. 30 (2-4): 213-242.
 http://dx.doi.org/10.1016/S0378-3839(99)00061-7
 
 Battjes, J.A., Bakkenes, H.J., Janssen, T.T., van Dongeren, A.R. 2004. Shoaling of subharmonic gravity waves. J. Geophys. Res., 109(C2): C02009.
 http://dx.doi.org/10.1029/2003JC001863
 
 Bowers, E.C. 1977. Harbour resonance due to set-down beneath wave groups. Journal of Fluid Mechanics. 79: 71-92.
 http://dx.doi.org/10.1017/S0022112077000044
 
 Cohen, L. 1995. Time Frequency Analysis: Theory and Applications. Prentice Hall Englewood Cliffs, New Jersey.
 
 Dong, G.H., X.Z., Ma, M., Perlin, Y.X., Ma, B., Yu, and G., Wang. 2009. Experimental Study of long wave generation on sloping bottoms. Coastal Engineering, 56(1), 82-89.
 http://dx.doi.org/10.1016/j.coastaleng.2008.10.002
 
 Kamphuis, J.W. 2000. Designing for low frequency waves. Proceedings of 27th International Conference on Coastal Engineering. Sydney, Australian. 1434-1447.
 
 Kostense, J.K. 1984. Measurements of surf beat and set-down beneath wave groups. Proceedings of 19th International Conference on Coastal Engineering. Houston, USA. 724-740.
 
 Longuet-Higgins, M.S. and R.W., Stewart. 1962. Radiation stress and mass transport in gravity waves with application to 'surfbeat'. Journal of Fluid Mechanics. 13: 481-504
 http://dx.doi.org/10.1017/S0022112062000877
 
 Mallat, S. 1999. A Wavelet Tour of Signal Processing. Academic Press. PMCid:407895
 
 Nagai, T., N., Hashimoto, T., Asai, et al. 1994. Relationship of a moored vessel in a harbor and a long wave caused by wave groups. Proceedings of 17th International Conference on Coastal Engineering. Kobe, Japan. 847-861.
 
 Schäffer, H.A. 1993. Second-orderwavemaker theory for irregularwaves.Ocean Engineering. 23 (1), 47–88.
 http://dx.doi.org/10.1016/0029-8018(95)00013-B
 
 Symonds, G.D.A., D.A., Huntley, and A.J., Bowen. 1982. Two-dimensional surf beat-long-wave generation by a time-varying breakpoint. Journal of Geophysical Research. 87(C1): 492-498.
 http://dx.doi.org/10.1029/JC087iC01p00492
 
 Yu, J. and C.C., Mei. 2000. Formation of sand bars under surface waves. Journal of Fluid Mechanics. 416: 315-348.
 http://dx.doi.org/10.1017/S0022112000001063
29
Ge, Shan, Guanyu Ren, Wengeng Wang, et al. "Gain measurement of microwave antenna with heterodyne bichromatic excitation in Rydberg atoms." Optics Express, May 13, 2024. http://dx.doi.org/10.1364/oe.523171.
Testo completo
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Huang, Longwei, Wenyue Lu, Jianmin Yang, and Qing Dong. "Measurement of wave forces on a modelled ice floe by plastic plate under bichromatic waves." Ships and Offshore Structures, May 27, 2022, 1–9. http://dx.doi.org/10.1080/17445302.2022.2062160.
Testo completo
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Li, Qinglin, Peter Yun, Tenghui Yang, Qiang Hao, Shougang Zhang, and Sihong Gu. "Noise suppression by differential detection of simultaneous electromagnetically induced transparency and absorption in counterpropagating bichromatic light." New Journal of Physics, October 10, 2023. http://dx.doi.org/10.1088/1367-2630/ad01d1.
Testo completoAbstract (sommario):
Abstract Well-established electromagnetically induced transparency (EIT) and absorption (EIA) have been applied to various applications including quantum computing, light storage, and precision measurement. Here, we propose and implement a differential detection scheme based on coexisting EIT and EIA signals in a double-Λ system with counterpropagating bichromatic laser fields, in which a differential coherent population trapping (diff-CPT) signal is extracted with a desired enhanced amplitude and highly suppressed common-mode noise. Compared to that of either EIT or EIA, the observed signal-to-noise ratio of the proposed method’s diff-CPT signal improved by one order of magnitude, which would benefit the implementation of high-performance CPT clocks. This technique may also be applied to magnetometers and precision spectroscopy.
32
Rodriguez-Lopez, Victor, Carlos Dorronsoro, and Alberto de Castro. "A metric-based image-formation model explains the improvement in subjective refraction using temporal defocus waves." Optometry and Vision Science, February 24, 2025. https://doi.org/10.1097/opx.0000000000002239.
Testo completoAbstract (sommario):
SIGNIFICANCE Direct subjective refraction (DSR) is a novel method for refractive error measurements that uses temporal changes in defocus and a flicker minimization task. The computational models developed here are a framework for improving this clinical method. PURPOSE This study aimed to model the measurement of refractive error with the DSR method, which uses rapid changes in optical power and a bichromatic (red/blue) stimulus. METHODS The polychromatic point spread function of the eye was used to simulate the retinal image projected in DSR method, and an image quality (IQ) metric was defined based on the spatial frequencies of the retinal image. Three tasks were modeled: blur minimization (BM), monochromatic flicker minimization (MFM), and polychromatic flicker minimization or DSR. A metric was defined for each task and studied through focus in a ±3-D range. Whereas BM was modeled using only the IQ of the projected images, MFM and DSR metrics were a function of the IQ of the average retinal image and a metric to quantify the similarity (flicker) in the image. The width of the through-focus peak was used to compare between tasks, and different values of pupil size and spherical aberration were studied. RESULTS The through-focus 90% peak width was 0.48, 0.16, and 0.19 D for BM, MFM, and DSR tasks, respectively, which agreed well with previous experimental data. The 90% peak width increased for small pupils and with increasing values of spherical aberration in BM and MFM, but it remained relatively constant in DSR model. CONCLUSIONS The developed models explained previous experimental findings that reported a higher repeatability of the DSR compared with the traditional refraction method.
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Dhote, Nihal, and Mohan Khond. "Experimental investigation and comparative analysis of various condition-based monitoring techniques for wear recognition in gear pump." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, January 26, 2025. https://doi.org/10.1177/13506501251313606.
Testo completoAbstract (sommario):
The purpose of the presented work is to recognize wear in different parts of the gear pump and to determine the wear particle contamination and particle types in oil. Oil samples were collected intermittently from the gear pump test rig to find the wear severity index and particle contamination. The percentage of large particles increased to 80.49% with wear severity index at the end of the test due to contamination. Hence ferrogram slides were prepared and observed under a bichromatic microscope to identify the types of wear particles. These ferrogram slides of oil samples show normal rubbing, severe sliding and cutting wear particles with some red oxide due to moisture content in the oil. Later on, to find the extent of damage to the gear pump parts, surface roughness and changed dimensions of these parts were measured by surface roughness measuring instrument and CMM. The model prepared based on these, gives the simulated results of wear varying from 27.3 µm to 87.8 µm shows a good correlation with actual measurement. In the last part of the work, the gear pump was removed from the system and worn-out parts were cut to prepare samples of the required sizes to observe under SEM. Morphology and texture results given by SEM help to study and predict the wear behaviour of system at particular operating conditions for condition monitoring. The combined approach of experimentation conducted here for quite a longer duration for such type of setup is the novelty of this work.
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Williams, M. R., F. Chi, M. T. Cashen, and H. Metcalf. "Bichromatic force measurements using atomic beam deflections." Physical Review A 61, no. 2 (2000). http://dx.doi.org/10.1103/physreva.61.023408.
Testo completo
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Kolaas, Jostein, Bjørn Hervold Riise, Kristian Sveen, and Atle Jensen. "Bichromatic synthetic schlieren applied to surface wave measurements." Experiments in Fluids 59, no. 8 (2018). http://dx.doi.org/10.1007/s00348-018-2580-6.
Testo completo
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Mežinska, S., A. Dorn, T. Pfeifer, and K. Bartschat. "Coherent control of multiphoton ionization of lithium atoms by a bichromatic laser field." Physical Review A 110, no. 1 (2024). http://dx.doi.org/10.1103/physreva.110.013116.
Testo completoAbstract (sommario):
We demonstrate a left-right asymmetry control of the photoelectron angular distribution in multiphoton ionization of Li atoms by a bichromatic laser field. By delaying the fundamental (780 nm) and its second harmonic relative to each other in steps of 130 attoseconds, we can vary the relative phase between the two laser fields with subwavelength accuracy and thereby steer the ejected electrons. Good agreement is found between the measurements and calculations at the appropriate intensities of the two harmonics. Published by the American Physical Society 2024
37
Kranenborg, J. W. M., T. Pauli, N. G. Jacobsen, et al. "Measurements and Modeling of Pore‐Pressure Gradients in the Swash Zone Under Large‐Scale Laboratory Bichromatic Waves." Journal of Geophysical Research: Oceans 128, no. 12 (2023). http://dx.doi.org/10.1029/2022jc019577.
Testo completoAbstract (sommario):
AbstractThe present work presents physical laboratory measurements of surface elevation and pore water pressures in a fine sand bed under bichromatic waves in a large‐scale laboratory experiment. This was done at three cross‐shore locations in the swash zone, with pressures being measured at different depths in the bed. The measurements show that the pore pressure signal decays and shifts with increased depth. These measurements are used to validate a practical model, based on the theory of Yamamoto et al. (1978, https://doi.org/10.1017/S0022112078003006) and Guest and Hay (2017, https://doi.org/10.1002/2016JC012257). The model corresponds well with the measurements (nRMSE < 0.2 and R2 > 0.95 for most probes) and shows that a frequency‐based model can reproduce the pressures in the bed, despite the bed being exposed during dry periods. Furthermore, the model provides the opportunity to calculate pressure gradients, both throughout the bed and at the bed surface. These modeled pressure gradients at the bed surface show that the vertical pressure gradient can have an important impact on the Shields parameter, thereby influencing sediment transport.
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Bolduc Beaudoin, Simon, Edouard Pinsolle, and Bertrand Reulet. "Counting statistics of ultrabroadband microwave photons." Physical Review Research 6, no. 4 (2024). https://doi.org/10.1103/physrevresearch.6.043238.
Testo completoAbstract (sommario):
We report measurements of counting statistics, average and variance, of microwave photons of ill-defined frequency: bichromatic photons, i.e., photons involving two well separated frequencies, and “white” broadband photons. Our setup allows for the analysis of single photonic modes of arbitrary waveform over the 1–10 GHz frequency range. The photon statistics are obtained by on-the-fly numerical calculation from the sampled time-dependent voltage. Using an ac+dc biased tunnel junction as a source of quantum microwave, we report an ultrawide squeezing spectrum representing a competitive source for entanglement generation (up to 0.9 billion measured entangled bits per second) easily achievable experimentally. We also report the observation of quantum steering by the tunnel junction, and show how the presence of squeezing of a broadband mode implies the existence of entanglement between two modes it encompasses. Published by the American Physical Society 2024
39
MELITO, LORENZO, BASHAR KHORBATLY, ALESSANDRO MARCONI, et al. "Lagrangian Measurements Of Surface Water Waves: Relation Between Drift Velocities And Set-Down." CoastLab 2024: Physical Modelling in Coastal Engineering and Science, May 7, 2024. http://dx.doi.org/10.59490/coastlab.2024.802.
Testo completoAbstract (sommario):
Since the work of Stokes on steady progressive surface waves (Stokes, 1847), there has been interest in fluid particle trajectories and associated mass flux. The original result obtained by Stokes was based on linear theory, and implied that there is a net forward drift in the fluid beneath a propagating surface wave. In the non-dimensional case, the drift velocity for a sinusoidal wave on a fluid of depth h is given by Recent works suggest that in many cases, particularly in waves propagating over a shear flow, a net Eulerian flow may develop, which is opposed to the Stokes drift. Monismith et al. (2007) suggested that in a deep-water setting, the net Eulerian backflow may cancel the Lagrangian Stokes drift on a pointwise basis. Further, Grue & Kolaas (2017) found good agreement with the theoretical findings of Longuet-Higgins (1953), except near the bottom and near the free surface, where boundary layers have a discernable impact on the induced flow. In recent field measurements, it was observed that the drift velocity correlates positively with the local average fluid depth (Bjørnestad et al., 2021). In other words, a wave with a set-up features a large forward drift, while a wave with a set-down features a negative net drift. The present work aims at investigating what observed in the field by means of laboratory experiments carried out in a wave flume, where monochromatic and bichromatic waves of different characteristics have been run.
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Han Yan-Chen, Li Yu-Dong, and Li Wei. "Research of the relationship between coherent population trapping (CPT) oscillation and Raman detuning." Acta Physica Sinica, 2024, 0. http://dx.doi.org/10.7498/aps.73.20231408.
Testo completoAbstract (sommario):
Coherent population trapping (CPT) oscillation is a transient oscillation phenomenon based on the CPT effects, which is related to the Raman detuning of the coherent bichromatic laser fields from the hyperfine ground-states of three-level Λ system. In this work, sawtooth wave is adopted to modulate the frequency of microwave signal to make Raman detuning change uniformly and stepping. Meanwhile, by building the relationship between the microwave frequency modulation rate and the change rate of Raman detuning, the effects of the change rate and mode of Raman detuning on CPT oscillation are analyzed respectively. The results reveal that when the Raman detuning is changing uniformly, the CPT oscillation will occur in the condition that the change rate is highly enough, and the excited oscillations show non-harmonic oscillation behavior. When the Raman detuning is triggered by step change, the excited CPT oscillation is a damping oscillation, and the oscillation frequency is equal to the Raman detuning. The modulation of Raman detuning is realized by using sawtooth wave to modulate the microwave frequency, and then the complete establishment of CPT state and the complete attenuation of CPT oscillation process are achieved. This work presents a new modulation method to realize the CPT oscillation, which shows great application potential in the field of weak magnetic measurements and atomic clocks.
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Florian, Grossmann, Hurther David, Sánchez-Arcilla Agustín, and M. Alsina Jose. "Data related to "Influence of the Initial Beach Profile on the Sediment Transport Processes during Post-storm Onshore Bar Migration."." September 16, 2022. https://doi.org/10.5281/zenodo.7085619.
Testo completoAbstract (sommario):
Abstract: Onshore bar migration is a characteristic bar behavior during post-storm beach recovery. The present large-scale experiments, feature bichromatic wave groups over an initially steep (1:15), fully-evolving beach. The same accretive wave condition is applied on two different post-storm beach profiles featuring outer and inner bars. They are characterized by a larger (smaller) shoreline erosion and a larger (smaller) outer breaker bar located farther away from (closer to) the shoreline depending on the larger (smaller) energy of the storm condition. After a considerable post-storm recovery time, similar equilibrium profiles are obtained, stressing the link between wave condition and equilibrium beach configuration. However, the evolution towards the equilibrium is different and depends on the initial morphological condition (post-storm beach profile). After the larger storm, the morphological evolution is termed AM and characterized by merging of the two bars (outer bar dissipation). After the smaller storm, the morphological evolution denoted as AN is characterized by onshore migration of the two bars with constant distance between them (bar maintenance). This study focuses on processes around the outer bar. During AN it features wave breaking, causing large suspended net offshore transport. AM, in contrast, mainly features bedload related to short wave asymmetries and low decomposed net transport rate magnitudes. High suspended net offshore transport occurs solely onshore of the outer bar trough. This causes filling of the bar trough and bar dissipation during migration. Additionally, processes around the outer bars are linked to accretion onshore of the bars and at the shoreline. About the data: The folder “Beach Profiles” contains the measurements from the mechanical profiler before and after each test. To save time, only the morphologically active section of the profiles was measured. Additionally, the folder contains the initial profiles at the start of each sequence (after application of the benchmark waves). Here the full profile was measured. The structure “MobFrame” contains the absolute cross-shore position of the mobile frame (from which detailed measurements were taken) in the considered tests. The folder “ACVP” contains structures with ensemble-averaged velocity and concentration measurements in vertical reference to the undisturbed bed level or a few bins below it (zeta<sub>0</sub>-coordinate system as described in the paper). For better interpretation of the measurements, it also features the ensemble-averaged intrawave instantaneous bed elevation (erosion depth) and the upper limit of the sheet flow layer. The folder “ADV” contains structures with the ensemble-averaged ADV data of each test. Apart from the velocity components of each ADV they contain the vertical elevation of each ADV with respect to the ACVP transceiver. The ADV measurements were not subject to the same vertical referencing procedure that was described in the paper for the near-bed ACVP measurements. The folder “OBS” contains structures with the ensemble-averaged OBS data of each test. Apart from the concentration measurements in each OBS sensor they contain the vertical elevation of each OBS with respect to the ACVP transceiver. The folder “ETA” contains structures with the ensemble-averaged surface elevation data of each test (from different instruments as described in the paper). The location of each instrument is given in absolute cross-shore coordinates x. For visualizing the near-bed concentration data, which may not be as trivial as visualizing the rest of the data, an example of MATLAB code is given: %S=ACVP_xx; %to choose which ACVP file you want to look into con=S.c; con(con<1)=1; %to cater for the cells where the logarithm is not defined xphase=linspace(0,1,length(S.solbed)).*ones(size(S.c,2),size(S.c,1)); figure; hold on; box on; [C,h]=contourf(xphase,S.z,log10(transpose(con)),[0:0.1:3]); cbh=colorbar; caxis([0 3]); set(h,'edgecolor','none'); tt=get(cbh,'Title'); set(tt,'String','$log_{10}(c)$ $[kg/m^3]$','Interpreter','Latex'); plot(xphase(1,:),S.solbed,'k','Linewidth',1.5); plot(xphase(1,:),S.solflo,'r','Linewidth',1.5); xlabel('$t/T_r$','Interpreter','Latex') ylabel('$\zeta_0$ $[m]$','Interpreter','Latex') set(gca,'Fontsize',18)
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Сhayka, O. M., and T. B. Peretyatko. "The reduction of hexavalent chromium and nitrates by Desulfuromonas YSDS-3, isolated from the soil of Yasiv sulfur mine." Ecology and Noospherology 29, no. 2 (2018). http://dx.doi.org/10.15421/031813.
Testo completoAbstract (sommario):
Such compounds as compounds of hexavalent chromium, nitrates and nitrites are one of the most distributed pollutants of the environment. The compounds of Cr (VI) are found in the soil, water and territories adjacent to mining enterprises in elevated concentrations. The hexavalent chromium has toxic, mutagenic and carcinogenic effect on living forms. Some sulfur-reducing bacteria are attractable for scientists attention like potential purification agentsto clear the wastewater from organic and inorganic pollutants. In this way,the purpose of our work is to study the patterns of the reduction of compounds of hexavalent chromium and nitrate by Desulfuromonas sp.YSDS-3, isolated from the soils of theYasiv sulfur mine. Bacteria were cultivated in modified Postgate C medium. To study the in fluence of Сr (VI) and NO3 on the sulfidogenic activity and the growth of bacteria they were grown in Postgate C medium containing sulfur (32 mM) and different concentrations of K2Cr2O7 (0,1–1 мМ) and КNO3 (5–15 мМ), as well as without sulfur for 10 days. The biomass of bacteria, Cr (VI), Cr (IІІ) and nitrites content was measured spectrophotometrically. Agar was used for the immobilization of the cells. Th ability of Desulfuromonas sp. YSDS-3 to utilize different electron acceptors, has been studied. It has been established that bacteria can growin media with presence of ferrum (III) citrate (at concentrations of 0.5 mM, 1 mM and 5 mM), MnO2 (at concentrations of 1 mM, 2 mM and 3 mM), KNO3 (at concentrations of 5 mM, 10 mM, 15mM) and cysteine (at a concentration of 3 mM). In a medium with potassium bichromate bacteria grow well at concentration of 0.1 mM. Perhaps, increase of K2Cr2O7 concentration from 0.5 to 1 mM leads to the suppression of growth and sulfidogenic activity of Desulfuromonas sp. YSDS-3. The quantitative measurement of Cr (VI) and Cr (III) ions in the cell-free medium had been shown that hexavalent chromium was completely reduced to Cr (III) in the presence of less than 0.5 mM of K2Cr2O7. At the same time, the increase of K2Cr2O7 caused a decreaseof reduction effectivity. It has been found that culture of Desulfuromonas sp.YSDS-3 is able to reduce nitrates and nitrites completely. At the same time, the process of sulfur reduction was oppressed in conditions of simultaneous presence of KNO3 and sulfur in the medium. There are various methods of wastewater purification from Cr (VI): the addition of aerobic or anaerobic consortia of microorganisms; treatment of sewage with various sorbents, such as natural glauconites, activated carbon, brown coal, etc. The most promising methods of the environment purification from pollutants are considered to be biological methods with exertion of microorganisms. For this purpose, in modern biotechnological approaches different methods of immobilization of microorganisms with organic and inorganic carriers are widely used. It has been found some patterns of chromium reduction by the cells of Desulfuromonas sp. YSDS-3, immobilized in agar. The model solution contained 0.5 mM Cr (VI) as an electron acceptor, and sodium lactate as a donor of electrons. It has been shown that the mood of Cr (VI) usage by immobilized Desulfuromonas sp. YSDS-3 cells was similar to the one by the liquid culture. The immobilized microbiota has a number of advantages, compared to the traditional method of artificial biological treatment of sewage in aerotanks: the immobilized cells can bee asily removed from the reaction medium; all the carriers are adapted for repeateduse; the immobilization of microbial enzymatic biomass enables the increase of the catalytic activity of some enzymes. It has been shown that it is possible to use the immobilized Desulfuromonas sp. YSDS-3 cells time after time to purify the environment from Cr (VI) pollutant.The cells of Desulfuromonas sp. YSDS-3 (the amount of cells was 1 g/L) completely reduced Cr (VI) to Cr (III) after 72 hours in the conditions of model medium addition containing 0.5 mM K2Cr2O7. Afterre-injection of 0.5 mM K2Cr2O7 in 72 hours, the reduction efficiency was about 70 %. Subsequent addition of 0.5 mM Cr (VI) led to lower reduction rate of Cr (VI): nearby 57 %. The rate of reduction of Cr (VI) depends on the concentration of the immobilized cells. With the increase of the amount of immobilized cells (2 g/L, 3 g/L, 5 g/L), it was observed more intense reduction of Cr (VI).The working concentration of the cells of Desulfuromonas sp. YSDS-3 about 5 g/L is the fit amount of bacteria for the most efficient reduction of Cr (VI). After the third introduction of the model solution, the reduction efficiency was 67 % after 72 hours of incubation. The duration and intensity of chromium reduction were directly dependent on the concentration of immobilized cells: if the amount of fixed cells was higher, the recovery process was more effective. The immobilized Desulfuromonas sp. YSDS-3 cells can completely detoxicate Cr (VI) in amount of 0.5 mM in 72 hours. The increase of the concentration of the cells accelerates the process of chromate utilization in the model solution. So, Desulfuromonas sp. YSDS-3 is promising for an aerobic treatment of the sewage from chromium-containing compounds.