scholarly journals Immobilized Luminescent Bacteria for the Detection of Mycotoxins under Discrete and Flow-Through Conditions

Biosensors ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 63 ◽  
Author(s):  
Olga Senko ◽  
Nikolay Stepanov ◽  
Olga Maslova ◽  
Rashid Akhundov ◽  
Anvar Ismailov ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Photobacterium Phosphoreum ◽  
Poly Vinyl Alcohol ◽  
Bacterial Cells ◽  
Flow Conditions ◽  
Luminescent Bacteria ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Flow Through

A biosensitive element in the form of bacterial Photobacterium phosphoreum cells immobilized in poly(vinyl alcohol) cryogel was tested for the determination of different mycotoxins under discrete and flow-through analysis conditions. The immobilized bioluminescent cells made it possible to quantify the presence of Ochratoxin A, Sterigmatocystin, Zearalenone, and Deoxynivalenon in aqueous media in a wide range of their concentrations (0.017–56 mg/L, 0.010–33 mg/L, 0.009–14 mg/L, and 0.026–177 mg/L, respectively) via measuring the quenching of cell luminescence. The flow conditions allowed the analysis sensitivity to be improved by an order of magnitude in terms of detected concentrations. Using the immobilized luminescent bacterial cells, we have shown the possibility of evaluating the efficiency of the mycotoxins’ hydrolysis under the action of enzymes. In this way, a 94 ± 4.5% efficiency of Zearalenone hydrolysis with hexahistidine-containing organophosphorus hydrolase for 1h-long treatment of the mycotoxin solution (100 mg/L) was shown.

Viscous flow in a cylindrical tube containing a line of spherical particles

1969 ◽  
Vol 38 (1) ◽  
pp. 75-96 ◽  
Author(s):  
Henry Wang ◽  
Richard Skalak
Keyword(s):  
Pressure Drop ◽  
Cylindrical Tube ◽  
Tube Diameter ◽  
Creeping Flow ◽  
Spherical Particles ◽  
Sphere Diameter ◽  
Wide Range ◽  
Mean Pressure ◽  
Order Of Magnitude ◽  
Flow Through

The viscous, creeping flow through a cylindrical tube of a liquid, which contains rigid, spherical particles, is investigated analytically. The spheres are located on the axis of the cylinder and are equally spaced. Solutions are derived for particles in motion and fixed, with and without fluid discharge. Numerical results are presented for the drag on each sphere and the mean pressure drop for a wide range of sizes and spacings of the spheres. The study is motivated by possible application to blood flow in capillaries, where red blood cells represent particles of the same order of magnitude as the diameter of the capillary itself. The results may also be of interest in other applications, such as sedimentation and fluidized beds. It is shown that there is little interaction between particles if the spacing is more than one tube diameter, and that the additional pressure drop over that for Poiseuille flow is less than 50% if the sphere diameter is less than 0·8 of the tube diameter.

scholarly journals Deformation and dynamics of red blood cells in flow through cylindrical microchannels

Soft Matter ◽  
2014 ◽  
Vol 10 (24) ◽  
pp. 4258-4267 ◽  
Author(s):  
Dmitry A. Fedosov ◽  
Matti Peltomäki ◽  
Gerhard Gompper
Keyword(s):  
Blood Flow ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Flow Resistance ◽  
Flow Conditions ◽  
Hydrodynamic Simulations ◽  
Wide Range ◽  
Flow Through ◽  
Cell Partitioning

The behavior of red blood cells (RBCs) in microvessels plays an important role in blood flow resistance and in the cell partitioning within a microcirculatory network. We employ mesoscopic hydrodynamic simulations to study the behavior and deformation of single RBCs in microchannels yielding the construction of diagrams of RBC shapes for a wide range of flow conditions.

scholarly journals Turbulent Flow through Random Vegetation on a Rough Bed

Water ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 2564
Author(s):  
Francesco Coscarella ◽  
Nadia Penna ◽  
Aldo Pedro Ferrante ◽  
Paola Gualtieri ◽  
Roberto Gaudio
Keyword(s):  
Flow Field ◽  
Flow Conditions ◽  
Bed Sediments ◽  
Turbulence Characteristics ◽  
Rigid Vegetation ◽  
Laboratory Flume ◽  
Rough Bed ◽  
Flow Through ◽  
Bed Roughness

River vegetation radically modifies the flow field and turbulence characteristics. To analyze the vegetation effects on the flow, most scientific studies are based on laboratory tests or numerical simulations with vegetation stems on smooth beds. Nevertheless, in this manner, the effects of bed sediments are neglected. The aim of this paper is to experimentally investigate the effects of bed sediments in a vegetated channel and, in consideration of that, comparative experiments of velocity measures, performed with an Acoustic Doppler Velocimeter (ADV) profiler, were carried out in a laboratory flume with different uniform bed sediment sizes and the same pattern of randomly arranged emergent rigid vegetation. To better comprehend the time-averaged flow conditions, the time-averaged velocity was explored. Subsequently, the analysis was focused on the energetic characteristics of the flow field with the determination of the Turbulent Kinetic Energy (TKE) and its components, as well as of the energy spectra of the velocity components immediately downstream of a vegetation element. The results show that both the vegetation and bed roughness surface deeply affect the turbulence characteristics. Furthermore, it was revealed that the roughness influence becomes predominant as the grain size becomes larger.

Hydrodynamic Characteristics of Wings in Circular Motion

2002 ◽  
Vol 46 (02) ◽  
pp. 92-98
Author(s):  
Zelik Segal
Keyword(s):  
Experimental Investigation ◽  
Circular Motion ◽  
Hydrodynamic Characteristics ◽  
Large Curvature ◽  
Small Curvature ◽  
Wide Range ◽  
Correct Determination ◽  
Order Of Magnitude ◽  
Wing Chord

Hydrodynamic characteristics of wings in circular motion are determined at present very approximately, as a rule, according to the solution of the problem on streamlining the wing by a small curvature nonviscid potential. However, in some practical cases the radius of the wing trajectory is of the same order of magnitude as the wing chord. That is why there is a necessity for a more correct determination of wing hydrodynamic characteristics, accounting for the relatively large curvature of the wing trajectory and the and viscosity. This paper presents a description and results of our theoretical and experimental investigation of the hydrodynamic characteristics of wings in a wide range of relative radiuses of their motion.

Free Molecule Flow Through a Vacuum Seal

1970 ◽  
Vol 92 (3) ◽  
pp. 405-410
Author(s):  
H. S. Yu ◽  
E. M. Sparrow
Keyword(s):  
Mass Flow ◽  
Numerical Solutions ◽  
Rarefied Gas ◽  
Coupled System ◽  
Mass Fluxes ◽  
Wide Range ◽  
Flow Through ◽  
Molecule Flow ◽  
Range Of Values

An analysis is made of the rate of the mass flow through a vacuum seal separating two rarefied gas environments. The determination of the mass throughflow characteristics involves the formulation and solution of a coupled system of six integral equations. The formulation is performed using the methods of kinetic theory. Numerical solutions are carried out for a wide range of values of the seal geometrical parameter. Mass flow results evaluated from these solutions are presented graphically. In addition, representative distributions of the mass fluxes at the participating surfaces are given.

Determination of Microgram Quantities of Thallium in Aluminum-, Iron-, and Nickel-Base Alloys

1974 ◽  
Vol 28 (3) ◽  
pp. 234-237 ◽  
Author(s):  
Keith E. Burke
Keyword(s):  
Atomic Absorption ◽  
Limit Of Detection ◽  
Aqueous Media ◽  
Extraction Procedure ◽  
Analytical Technique ◽  
Copper Indium ◽  
Order Of Magnitude ◽  
Nickel Base ◽  
Trace Constituents

Chemical techniques are required for the determination of trace constituents in commercial nickel and its alloys. An adequate method does not exist for the determination of microgram quantities of thallium; therefore, an extraction-atomic absorption method has been developed. Trace quantities of thallium in nickel are quantitatively extracted from a 10% hydrochloric acid solution containing 2% ascorbic acid and 9% potassium iodide by a 5% solution of tri- n-octylphosphine oxide in 4-methylpentane-2-one (MIBK). The MIBK extract containing the thallium is then nebulized directly into the atomic absorption flame. The concentration range for the determination of thallium in MIBK is an order of magnitude lower than for aqueous media. The proposed analytical technique is accurate and rapid and has a precision (σ) of ±0.15 ppm at the 2.00 ppm level. The limit of detection is 0.1 ppm of thallium. The method is also applicable to aluminum- and iron-base alloys. The solvent extraction procedure used to isolate thallium has also been validated for antimony, bismuth, lead, and tin and can also be applied to the determination of cadmium, copper, indium, and zinc.

DEVELOPMENT OF MEMBRANE SENSORS BASED ON NEW HYBRID MATERIALS FOR THE DETERMINATION OF SULFUR AND MEDICI-NAL SUBSTANCES IN DOMESTIC AND INDUSTRIAL EFFLUENTS

2015 ◽  
Vol 4 (4) ◽  
pp. 31-32 ◽  
Author(s):  
Бобрешова ◽  
O Bobreshova ◽  
Денисова ◽  
T Denisova ◽  
Паршина ◽  
...  
Keyword(s):  
Hybrid Materials ◽  
Aqueous Media ◽  
Industrial Effluents ◽  
Industrial Enterprises ◽  
Anesthetic Agents ◽  
Medical Institutions ◽  
Wide Range ◽  
Touch Devices ◽  
Data Portability

Developed potentiometric PD sensors with new hybrid materials based on perfluorinated sulfokationoobmennyh mem-branes Nafion and MF 4SK contain-ing nanoparticles of hydrated metal oxide (including a functionalized surface) to quant-tively determination of sulfur compounds and is widely used in medical practice, local anesthetic agents (procaine, lidoka-in) in multicomponent aqueous media. Using sensors in the similarity-tion of composite materials can significant-ly increase their Chuv-tivity to define the components that helps to increase the accuracy of determination.. Easy to use, no sample preparation, automatic pro-cessing of data portability obespe Chiva-low labor intensity analysis, which makes available to develop mye-touch devices for a wide range of control organi-zation-tions and services for environmental monitoring of water flows of medical institutions and industrial enterprises.

Influences of experimental parameters on the stability of a benzoporphyrin drug in water/ethanol mixtures: a statistical approach investigation

2005 ◽  
Vol 09 (09) ◽  
pp. 609-616 ◽  
Author(s):  
André Luiz Tessaro ◽  
Daniela Martins Fernandes ◽  
Ailton José Terezo ◽  
Vagner Roberto de Souza ◽  
Noboru Hioka
Keyword(s):  
Water Content ◽  
Aqueous Media ◽  
Solvent Mixtures ◽  
Wide Range ◽  
Experimental Parameters ◽  
Carboxylic Groups ◽  
Minimum Number ◽  
Set Up ◽  
The Stability

The benzoporphyrin derivative, named B3B, is a promising new drug for application in photodynamic therapy. In aqueous organic solvent mixtures, B3B, can be used in topical application for superficial diseases, like for skin cancer. In this paper, the self-aggregation phenomena of porphyrin molecules in aqueous media was investigated using a chemometric tool to evaluate the effects of experimental variables on the stability of the B3B monomer in water/ethanol mixtures. A 23 factorial design was employed which permitted determination of the magnitude of experimental parameters which influence aggregation of the drug at different pHs using the minimum number of experiments. At first, the pK a values of the B3B in water/ethanol mixtures were determined by spectrophotometric measurements, resulting in pK a1 = 3.3 and pK a2 = 5.7, corresponding to the imino nitrogens and carboxylic groups, respectively. The experimental variables (B3B concentration, time and water/ethanol composition) were evaluated in three protonation states of the drug, at pH 7.0, 4.1 and 2.6. The two levels (low and high) were set up at: time 5 (-) and 360 minutes (+); [B3B] 4.4 × 10-6(-) and 26.5 × 10-6 M (+); and water content in ethanol 40 (-) and 60% (+). The main parameter that determines the magnitude of the effects seems to be the charge component of B3B, which can be modulated by the pH. The results from the 23 fractional design indicated that the main variable inducing B3B aggregation is the water percentage in ethanol at each pH selected. The magnitude of this effect was pronounced at pH 4.1 where the carboxylic and nitrogen free base forms of B3B are maintained. The factors of time and [B3B], despite being small, are not insignificant. Finally, the effect of water content was investigated in a wide range of water percentage in these three pHs.

Development of a method for multielemental determination in water by EDXRF with radioisotopic source of 238Pu.

2019 ◽  
Vol 7 (2A) ◽  
Author(s):  
Camilo Fuentes Serrano ◽  
Juan Reinaldo Estevez Alvares ◽  
Alfredo Montero Alvarez ◽  
Ivan Pupo Gonzales ◽  
Zahily Herrero Fernandez ◽  
...  
Keyword(s):  
Thin Layer ◽  
Expanded Uncertainty ◽  
Considerable Decrease ◽  
X Ray ◽  
Precipitation Efficiency ◽  
Method Of Determination ◽  
Sensitivity Curves ◽  
Order Of Magnitude ◽  
Metrological Parameters

A method for determination of Cr, Fe, Co, Ni, Cu, Zn, Hg and Pb in waters by Energy Dispersive X Ray Fluorescence (EDXRF) was implemented, using a radioisotopic source of 238Pu. For previous concentration was employed a procedure including a coprecipitation step with ammonium pyrrolidinedithiocarbamate (APDC) as quelant agent, the separation of the phases by filtration, the measurement of filter by EDXRF and quantification by a thin layer absolute method. Sensitivity curves for K and L lines were obtained respectively. The sensitivity for most elements was greater by an order of magnitude in the case of measurement with a source of 238Pu instead of 109Cd, which means a considerable decrease in measurement times. The influence of the concentration in the precipitation efficiency was evaluated for each element. In all cases the recoveries are close to 100%, for this reason it can be affirmed that the method of determination of the studied elements is quantitative. Metrological parameters of the method such as trueness, precision, detection limit and uncertainty were calculated. A procedure to calculate the uncertainty of the method was elaborated; the most significant source of uncertainty for the thin layer EDXRF method is associated with the determination of instrumental sensitivities. The error associated with the determination, expressed as expanded uncertainty (in %), varied from 15.4% for low element concentrations (2.5-5 μg/L) to 5.4% for the higher concentration range (20-25 μg/L).

Temperature Dependence of the Self-Assembled Styrene Based Random Ionomers in Aqueous Solution

2003 ◽  
Vol 775 ◽  
Author(s):  
Sung-Hwa Oh ◽  
Ju-Myung Song ◽  
Joon-Seop Kim ◽  
Hyang-Rim Oh ◽  
Jeong-A Yu
Keyword(s):  
Partition Coefficients ◽  
Room Temperature ◽  
Aqueous Media ◽  
The Self ◽  
Spectroscopic Methods ◽  
Ion Content ◽  
Repeat Units ◽  
Notable Effect ◽  
Order Of Magnitude ◽  
Experimental Errors

AbstractSolution behaviors of poly(styrene-co-sodium methacrylate) were studied by fluorescence spectroscopic methods using pyrene as a probe. The mol% of methacrylate was in the range 3.6–9.4. Water and N,N-dimethylforamide(DMF) mixture was used as a solvent (DMF/water = 0.2 mol %). The critical micelle (or aggregation) concentrations of ionomers and the partition coefficients of pyrene were obtained the temperature range 10–80°C. At room temperature, the values of CMCs (or CACs) were in the range 4.7 ×10-6 5.3 ×10-6 g/mL and we could not find any notable effect of the content of ionic repeat units within the experimental errors. Unlike CMCs, as the ion content increased, partitioning of pyrene between the hydrophobic aggregates and an aqueous media decreased from 1.5 ×105 to 9.4 ×104. As the temperature increased from 10 to 80 °C, the values of CMCs increased less than one order of magnitude. While, the partition coefficients of pyrene decreased one order of magnitude and the effect of the ion content became negligible.

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