scholarly journals Acrylated Chitosan Nanoparticles with Enhanced Mucoadhesion

Polymers ◽  
2018 ◽  
Vol 10 (2) ◽  
pp. 106 ◽  
Author(s):  
Shaked Eliyahu ◽  
Anat Aharon ◽  
Havazelet Bianco-Peled
Keyword(s):  
Chitosan Nanoparticles ◽  
Particle Method ◽  
Time Intervals ◽  
Additional Indication ◽  
Nmr Data ◽  
Incubation Periods ◽  
Mucin Glycoprotein ◽  
Michael Type Addition ◽  
Flow Through ◽  
Potential Stability

The aim of this study was to investigate the effect of acrylate modification on the mucoadhesion of chitosan at the nanoscale. Nanoparticles were fabricated from acrylated chitosan (ACS) via ionic gelation with tripolyphosphate and were characterized in terms of size, zeta potential, stability, and nanoparticle yield. Chitosan (CS) nanoparticles, serving as a control, were fabricated using the same procedure. The mucoadhesion of the nanoparticles was evaluated using the flow-through method after different incubation periods. The retention percentages of ACS nanoparticles were found to be significantly higher than those of CS nanoparticles, for all studied time intervals. An additional indication for the increased mucoadhesion of ACS nanoparticles was the increase in particle size obtained from the mucin particle method, in which mucin and nanoparticles are mixed at different ratios. NMR data verified the presence of free acrylate groups on the ACS nanoparticles. Thus, the improved mucoadhesion could be due to a Michael-type addition reaction between the nanoparticles and thiol groups present in mucin glycoprotein, in addition to entanglements and hydrogen bonding. Overall, ACS nanoparticles exhibit enhanced mucoadhesion properties as compared to CS nanoparticles and could be used as vehicles for drug delivery systems.

Role of Histamine and Leucotaxin in Function of Cellular Defense Mechanism

1956 ◽  
Vol 184 (2) ◽  
pp. 296-300 ◽  
Author(s):  
László Kátó ◽  
Béla Gözsy
Keyword(s):  
Fluid Flow ◽  
Tissue Damage ◽  
Inflammatory Process ◽  
Defense Mechanism ◽  
Volatile Oils ◽  
Time Intervals ◽  
Cellular Defense ◽  
Intradermal Administration ◽  
Flow Through

Experiments are presented to the effect that in an inflammatory process histamine and leucotaxin appear successively at different and orderly time intervals, thus assuring an increased fluid flow through the capillary wall. Histamine is released not only in the inflammatory process but also by intradermal administration of such substances (volatile oils or their components) which induce neither the triple response of Th. Lewis nor any tissue damage. This could be explained by the fact that in the tissues histamine is ‘present’ but leucotaxin is ‘formed.’

CFD Simulation of Wall-Bounded Laminar Flow Through Screens: Part II — Mixing Characterization

2020 ◽  
Author(s):  
W. Abou Hweij ◽  
F. Azizi
Keyword(s):  
Cfd Simulation ◽  
Flow Behavior ◽  
Particle Method ◽  
Immiscible Fluids ◽  
Laminar Flows ◽  
Operating Conditions ◽  
Static Mixers ◽  
Flow Through ◽  
Dispersive Mixing ◽  
Lagrangian Particle Method

Abstract This paper characterizes the mixing behavior of laminar flows within a circular pipe equipped with plain woven meshes or screens, acting as static mixers. In this quest, their performance was numerically investigated using the Lagrangian particle method in a commercial CFD solver, whereby the effect of changing the screen geometry, number of screens, inter-screen spacing, and operating conditions were considered. Mixing was addressed from a distributive and dispersive perspectives using both qualitative and quantitative descriptions. The distributive mixing indicated that a central injection of a single fluid should be coupled with a short inter-screen spacing to better spread the particles and enhance mixing as opposed to a larger inter-screen spacing. On the contrary, the mixing of two immiscible fluids of similar properties reveal that a large inter-screen spacing is recommended. From a dispersive mixing perspective, extensional efficiency contours revealed that the fluid would undergo all three modes of flow behavior, each of which dominating a certain region depending on the location with respect to the screen. Finally, it was interesting to find that a coarser screen geometry consistently outperformed finer screens in spreading and mixing the particles.

scholarly journals Modeling Water Balance of Dammed Lakes Using Computer Code Matlab-Simulink/ Modelowanie Bilansu Wodnego Piętrzonych Jezior Za Pomocą Programu Komputerowego Matlab-Simulink

2014 ◽  
Vol 14 (3) ◽  
pp. 5-14
Author(s):  
Ryszard Błażejewski ◽  
Sadżide Murat-Błażejewska ◽  
Martyna Jędrkowiak
Keyword(s):  
Water Balance ◽  
Computer Code ◽  
Water Levels ◽  
Time Interval ◽  
Lake Surface ◽  
Time Intervals ◽  
Matlab Simulink ◽  
Surface Evaporation ◽  
Flow Through ◽  
Good Agreement

Abstract The paper presents a water balance of a flow-through, dammed lake, consisted of the following terms: surface inflow, underground inflow/outflow based on the Dupuit’s equation, precipitation on the lake surface, evaporation from water surface and outflow from the lake at which a damming weir is located. The balance equation was implemented Matlab-Simulink®. Applicability of the model was assessed on the example of the Sławianowskie Lake of surface area 276 ha and mean depth - 6.6 m, Water balances, performed for month time intervals in the hydrological year 2009, showed good agreement for the first three months only. It is concluded that the balancing time interval should be shorter (1 day) to minimize the errors. For calibration purposes, measurements of ground water levels in the vicinity of the lake are also recommended.

Effect of cold shock, liquid storage, and pellet-freezing on successive ram ejaculates

1967 ◽  
Vol 18 (6) ◽  
pp. 959 ◽  
Author(s):  
S Salamon ◽  
RJ Lightfoot
Keyword(s):  
Cold Shock ◽  
Egg Yolk ◽  
Time Intervals ◽  
Liquid Storage ◽  
Incubation Periods ◽  
Before And After ◽  
The Mean ◽  
Pellet Form ◽  
Mean Time ◽  
Increased Susceptibility

(1) Nine successive ejaculates were collected from each of four Merino rams on three occasions at intervals of three days. The mean time intervals between successive ejaculates on the first, second, and third collecting days were respectively 41, 28, and 30 min. Aliquots from alternate ejaculates (first, third, fifth, seventh, and ninth) were cold-shocked before and after 1 : 4 dilution with an egg yolk–glucose–citrate diluent. Similarly diluted aliquots were stored at +2°C for 16 days and also frozen in pellet form after addition of 6% glycerol to a final 1:8 dilution. (2) Both undiluted and diluted spermatozoa showed increased susceptibility to cold shock with succession of ejaculates. Egg yolk–glucose–citrate diluent ameliorated the deleterious effect. (3) There were no marked differences in reanimation at thawing of pellet-frozen successive ejaculates. During a 6 hr incubation of the thawed semen at 37°, however, there were significant ejaculate differences in viability, the ninth collection having the lowest value. The mean reanimation of pellet-frozen spermatozoa after thawing was 58.7°. During incubation periods of 2,4, and 6 hr at 37°C, 47, 60, and 70% respectively of the original post-thawing motile spermatozoa became immotile. (4) During storage for 16 days at +2°C, the third and fifth ejaculates gave the best viability values. There were, however, no marked differences between ejaculates during the first 6 days of storage. (5) No firm relationships were found between cold shock values and subsequent viability during liquid storage or recovery after pellet-freezing.

scholarly journals Populations of Xylella fastidiosa in Plants Required for Transmission by an Efficient Vector

1997 ◽  
Vol 87 (12) ◽  
pp. 1197-1201 ◽  
Author(s):  
B. L. Hill ◽  
A. H. Purcell
Keyword(s):  
Host Species ◽  
Cynodon Dactylon ◽  
Xylella Fastidiosa ◽  
Bermuda Grass ◽  
Stem Tissue ◽  
Plant Host ◽  
Time Intervals ◽  
Incubation Periods ◽  
Efficient Vector ◽  
Over Time

Xylella fastidiosa, a xylem-limited bacterium that causes Pierce's disease (PD) of grapevine and other diseases, is transmitted efficiently by xylem-feeding leafhoppers. Acquisition of a PD strain of X. fastidiosa by the blue-green sharpshooter (BGSS) from five plant host species—grapevine (Vitis vinifera), Himalayan blackberry (Rubus discolor), California mugwort (Artemisia douglasiana), watergrass (Echinochloa crus-galli), and Bermuda grass (Cynodon dactylon)—was tested at various time intervals after vector inoculation. The minimum incubation periods in plant hosts before BGSS acquired X. fastidiosa were 4, 22, 29, and 25 days for grapevine, blackberry, mugwort, and watergrass, respectively. There were no transmissions by vectors or recoveries of X. fastidiosa by culturing from Bermuda grass in 133 attempts, including 80 attempts with the green sharpshooter, Draeculacephala minerva. The first acquisitions and subsequent transmissions by BGSS occurred after X. fastidiosa multiplied to a population of about 104 CFU/g of stem tissue. Higher populations of bacteria in plants resulted in higher rates of transmission. In grapevine, the rate of transmission increased over time (4.5% in the first 10 days to 55% after day 25) as the maximum number of viable CFU of X. fas-tidiosa recovered by culturing also increased (from 5 × 105 CFU/g during the first 10 days to 5 × 108 after day 25).

Fluid flow through rock fractures undergoing chemical interactions: A look at pressure solution from an experimental perspective

2020 ◽  
Author(s):  
Harald Milsch ◽  
Chaojie Cheng
Keyword(s):  
Confining Pressure ◽  
Time Dependent ◽  
Tensile Fracture ◽  
Pressure Solution ◽  
Chemical Interactions ◽  
Fracture Permeability ◽  
Time Intervals ◽  
Microstructural Investigation ◽  
Sandstone Sample ◽  
Flow Through

<p>Fluid transport within the Earth’s crust is predominantly controlled by planar void space like fractures and crack networks. Characterizing the time dependent hydro-mechanical properties of these rock-structural elements therefore is of paramount importance for natural geosystem understanding and geotechnical applications alike.</p><p>In this contribution we outline the protocol and results of a long term flow-through experiment of more than 4 months conducted with one single-fractured, pure quartz, and centimeter-sized Fontainebleau sandstone sample displaying very low matrix permeability.</p><p>The cylindrical sample was axially split to generate one single and rough tensile fracture and the obtained sample halves were manually offset in axial direction by 200 µm resulting in geometric mismatch of the two fracture faces yielding asperity contacts and high contact stresses upon loading.</p><p>The experiment was conducted at constant temperature (333 K) and pore fluid pressure (1 MPa), three different confining pressure levels (2, 18, and 30 MPa), and with two different fluids (deionized water and 0.3 mM SiO<sub>2</sub> solution).</p><p>The sample was continuously flown through and the experimental procedure consisted of several successive stages during which confining pressure and fluid type were systematically varied in time intervals of several weeks each.</p><p>The experiment yielded results of continuous sample and fracture permeability measurements, the derivation of time dependent changes in hydraulic fracture aperture, a complete ICP-OES chemical analysis of Si concentrations in the effluent in one day time intervals, and a full before/after microstructural investigation of mechanical aperture, contact area ratio, as well as asperity and free fracture face morphology.</p><p>Overall, this experiment yields evidenced insights into the low-temperature dynamics of fracture permeability when, concurrently, chemical interactions between fluid and rock are taking place. Moreover, the investigations emphasize the role of pressure solution (creep) in this context as opposed to, e.g., free face dissolution or subcritical crack growth. Finally, conclusions are drawn on the rate-limiting sub-process of pressure solution with possible implications for fluid history matching in quartz-rich fractured rock masses.</p>

scholarly journals Numerical Simulation of Water Flow through a Nano-Hydraulic Turbine of Waterfall-Type by Particle Method

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Tomomi Uchiyama ◽  
Haruki Fukuhara ◽  
Shouichiro Iio ◽  
Toshihiko Ikeda
Keyword(s):  
Numerical Simulation ◽  
Water Flow ◽  
Particle Method ◽  
Hydraulic Turbine ◽  
Flow Through

Preliminary Results of Testing a Solar Air Heater Equipped with Turbulators

2017 ◽  
Author(s):  
Miroslaw Zukowski ◽  
Grzegorz Woroniak
Keyword(s):  
Solar Radiation ◽  
Thermal Performance ◽  
Meteorological Data ◽  
Air Flow ◽  
Solar Air Heater ◽  
Outlet Temperature ◽  
Time Intervals ◽  
Measurement Results ◽  
New Type ◽  
Flow Through

The paper presents the thermal performance of a newly designed device for preheating ventilation air. This new type of a solar air collector is equipped with turbulators to increase heat exchange and eventually to obtain more energy from the Sun. Support elements of this type have not yet been implemented in such heat exchangers. The panel has the following dimensions: width – 0.97 m, length – 1.9 m, thickness – 0.1 m, the area where solar radiation enters the collector – 1.49 m2. Air flow through the exchanger is forced by two radial high flow fans, typically used to cool down servers. The test stand beside the collectors is equipped with an inlet and outlet temperature data recorder and an anemometer to control the air flow rate through the collector. Meteorological data such as solar radiation, wind speed and ambient temperature is obtained from a weather station. The parameters of the working installation have been analysed through the monitoring of measurement variables collected on one-minute time intervals from April to September 2016. The measurement results have been used to determine the thermal performance of the air solar collector of this type. The results of the energy analysis have shown the validity of such an installation.

scholarly journals Mesoscale dynamic coupling of finite- and discrete-element methods for fluid–particle interactions

2014 ◽  
Vol 372 (2021) ◽  
pp. 20130386 ◽  
Author(s):  
S. Srivastava ◽  
K. Yazdchi ◽  
S. Luding
Keyword(s):  
Stokes Equations ◽  
Particle Density ◽  
Coarse Graining ◽  
Particle Method ◽  
Discrete Element ◽  
Fluid Particle ◽  
Momentum Exchange ◽  
Wide Range ◽  
Flow Through ◽  
Element Method

A new method for two-way fluid–particle coupling on an unstructured mesoscopically coarse mesh is presented. In this approach, we combine a (higher order) finite-element method (FEM) on the moving mesh for the fluid with a soft sphere discrete-element method for the particles. The novel feature of the proposed scheme is that the FEM mesh is a dynamic Delaunay triangulation based on the positions of the moving particles. Thus, the mesh can be multi-purpose: it provides (i) a framework for the discretization of the Navier–Stokes equations, (ii) a simple tool for detecting contacts between moving particles, (iii) a basis for coarse-graining or upscaling, and (iv) coupling with other physical fields (temperature, electromagnetic, etc.). This approach is suitable for a wide range of dilute and dense particulate flows, because the mesh resolution adapts with particle density in a given region. Two-way momentum exchange is implemented using semi-empirical drag laws akin to other popular approaches; for example, the discrete particle method, where a finite-volume solver on a coarser, fixed grid is used. We validate the methodology with several basic test cases, including single- and double-particle settling with analytical and empirical expectations, and flow through ordered and random porous media, when compared against finely resolved FEM simulations of flow through fixed arrays of particles.

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