Linear Flow Rate Research Articles

Study of functional state of microcirculatory channel system in periodontal tissues in persons of different age groups

Relevance. The study of age-related features of microcirculation in periodontal tissues, using non-invasive functional research methods, allows us to develop the optimal range of therapeutic measures, as well as form a “personalized therapeutic case”.Purpose. Study of the functional state of the microvasculature in the tissues of the parodont in individuals of various age groups.Materials and methods. A standard dental examination of 80 patients was carried out, the sample of participants was ranked in 4 groups by age: 1 group – 12 years old, 2 group – 15 years old, 3 group – from 16 to 18 years old, 4 group – from 22 to 24 years old. Hygiene and periodontal indices were determined for all patients, such as papillarymarginal-alveolar (PMA) in the Parma modification, the Mulleman bleeding index in the Cowell modification (SBI), and the simplified Green Vermillion index of oral hygiene (OHI–s), caries intensity indicators for a permanent bite (CPI), as well as ultrasound dopplerography of periodontal tissues using the apparatus "Minimax-Doppler-K".Results. When studying microcirculation in periodontal tissues, distinctive characteristics of linear (Vas) and volumetric (Qas) blood flow rates, as well as indicators of pulsation indices (PI) and peripheral resistance (RI) in people of different age groups were recorded.Conclusions. This study confirms the presence of various hemodynamic indicators of periodontal tissues in the studied groups, which is due to structural features of the circulatory system in age periods.

Assessment of peridontal vessels hemodynamics among patients with diabetes mellitus type 1

Relevance. Processes of disturbance of regional hemodynamics, tissue blood flow, insufficiency of transcapillary metabolism and antioxidant system caused by dysfunction of periodontal vascular endothelium among patients with diabetes type 1 directly lead to diabetic microangiopathy accompanied by decrease of level of microcirculation and perfusion of periodontal tissues among patients with absolute insulin insufficiency. The reduction of linear and volumetric blood flow rates in periodontal vessels among patients with type 1 diabetes compared to values obtained by ultrasonic dopplerography in healthy patients can be considered as distinctive features of the manifestation of this systemic disease on microcirculation of periodontal tissues.Purpose. To evaluate the hemodynamics of periodontal vessels among patients with diabetes mellitus type 1 and without diabetes before and after conservative periodontal therapy.Materials and methods. 40 patients at the age 20-30 years were surveyed: 20 patients with diabetes mellitus type 1 and 20 patients without diabetes. All subjects underwent dental examination. To study the state of microcirculation of periodontal tissues patients of both groups underwent high-frequency ultrasound Doppler “Minimax-doppler-k”. Further was conducted professional oral hygiene complex with training in rules of individual oral hygiene. Reexamination was scheduled after 4 weeks. Results. During the conduction have been registered average baseline of the linear (Vam) and volumetric (Qam) blood flow in periodontal vessels in patients with diabetes mellitus type 1 and without diabetes. Average linear (Vam) and volumetric (Qam) blood flow before the conduction of professional oral hygiene complex were considerably lower compared to patients without diabetes. This points reduction of microcirculation and perfusion of periodontal tissues in patients with diabetes mellitus type 1 and without diabetes. Reassessment of blood flow in periodontal tissues in 4 weeks after professional oral hygiene revealed an increase in rate of microcirculation in periodontal tissues among patients with diabetes mellitus type 1 and without diabetes. Conclusion. Our study confirms the theory of hemodynamic impairment and local hemostasis in patients with type 1 diabetes, which is reflected in the appearance of trophic disorders of an inflammatory-dystrophic nature and a decrease in hemodynamic parameters. After conservative periodontal therapy, we revealed positive changes in hemodynamics of periodontal vessels, which was recorded using ultrasound dopplerography. Our results will allow us to select the optimal algorithms for the timely diagnosis, prevention and treatment of dental diseases in patients with type 1 diabetes in future.

Chemometric handling of spectral-temporal dependencies for liquid chromatography data with online registering of excitation-emission fluorescence matrices

In this work, the generation and posterior chemometric resolution of third-order data, obtained from samples processed by liquid chromatography (LC) with online registering of excitation-emission fluorescence matrices (EEM) is reported. Samples were instrumentally processed in a relatively short time, and neither an intentional reduction of the linear flow rate nor an unconventional fluorescence instrument were required. Through the inclusion of external circuitry based on open-source hardware, the occurrence time of each individual fluorescence intensity reading was recorded. For the reported instrumental setup, irregular signal sampling was verified. In order to consider samples-specific time measurements, the PARAFAC (Parallel Factor Analysis) algorithm, and the derived APARAFAC (Augmented-PARAFAC) strategy, were adapted. The functional information was employed during the computational stages, through the development and implementation of smoothing strategies. To tackle differences between the rate of spectral acquisition and the rate of change in the concentration of the mobile fluorophores, Expectation Maximization was implemented. Data from samples with one calibrated analyte (Vitamin B6-Pyridoxine), in presence of uncalibrated interferents, were modeled. In order to preserve the original data structure, unfolding data operations were minimized. The resolved profiles of all species were in agreement with the corresponding chromatographic and spectral references. Results suggest that the effects derived from the loss of trilinearity previously reported in the literature for LC-EEM data, depend on interpretation and subsequent modeling of the data. The reported strategies can be useful with other flow techniques and kinetics.

Simultaneous elimination of hydrated silica, arsenic and phosphates from real groundwater by electrocoagulation using a cascade-shaped up-flow reactor

This paper deals with the elimination of hydrated silica, arsenic, and phosphates from real groundwater collected in central Mexico (arsenic 22 μg L−1, hydrated silica 161 mg L−1, sulfate 50 mg L−1, phosphate 0.41 mg L−1, pH 7.6 and conductivity 508 μS cm−1) by electrocoagulation (EC), using a cascade-shaped up-flow reactor with a six-cell stack open to the atmosphere at the top. Aluminum plates were used as electrodes. The influence of both current density (4 ≤ j ≤ 10 mA cm−2) and mean linear flow rates (1.2 ≤ u ≤ 4.8 cm s−1) in the EC reactor on the removal efficiency of hydrated silica, arsenic, and phosphates were examined. The best removal of arsenic after EC (reaching a residual concentration, CAs = 1.5 μg L−1) was obtained at j = 10 mA cm−2 and u = 1.2 cm s−1, meeting the World Health Organization (WHO) recommendation (<10 μg L−1), while the residual concentrations of hydrated silica, phosphates and sulfates were Chs = 42 mg L−1, CPO43− = 0.03 mg L−1 and CSO42− = 35 mg L−1, respectively. The experimental conditions at j = 10 mA cm−2 and u = 1.2 cm s−1, produced a large amount of coagulant (85.4 mg L−1), so this condition was repeated in a second round of the EC process to further reduce the concentration of hydrated silica. This time, Chs = 2.6 mg L−1 and CSO42− = 30 mg L−1 were obtained with the complete abatement of arsenic and phosphates. The total cost of the EC was 1.093 USD m−3, which included the electrolytic energy consumption, the price of aluminum, the costs of pumping and confinement of sludge, emphasizing that the calculation was based on Mexican costs. SEM-EDS, XRD, XRF and FTIR analyses on flocs revealed that the coagulant reacted with silica forming aluminum silicates, while arsenic and phosphates were removed by adsorption on flocs. The partial removal of sulfates (40%) is associated with weak adsorption on aggregates.

Removal of fluoride and hydrated silica from underground water by electrocoagulation in a flow channel reactor.

This paper concerns simultaneous removal of fluoride and hydrated silica from groundwater (4.08mgL-1 fluoride, 90mgL-1 hydrated silica, 50mgL-1 sulfate, 0.23mgL-1 phosphate, pH 7.38 and 450μS cm-1 conductivity) by electrocoagulation (EC), using an up-flow EC reactor, with a six-cell stack in a serpentine array, opened at the top of the cell to favor gas release. Aluminum plates were used as sacrificial electrodes. The effect of current density (4≤j≤7mAcm-2) and mean linear flow rate (1.2≤u≤4.8cms-1), applied to the EC reactor, on the elimination of fluoride and hydrated silica was analyzed. The removal of fluoride followed the WHO guideline (<1.5mgL-1), while the hydrated silica was abated at 7mAcm-2 and 1.2cms-1, with energy consumption of 2.48kWh m-3 and an overall operational cost of 0.441 USD m-3. Spectroscopic analyses of the flocs by XRD, XRF-EDS, SEM-EDS, and FTIR indicated that hydrated silica reacted with the coagulant forming aluminosilicates, and fluoride replaced a hydroxide from aluminum aggregates, while sulfates and phosphates were removed by adsorption process onto the flocs. The well-engineered EC reactor allowed the simultaneous removal of fluoride and hydrated silica.

Micropolar fluid flow through the membrane composed of impermeable cylindrical particles coated by porous layer under the effect of magnetic field

In the present work, the magnetohydrodynamic flow of a micropolar fluid through the membrane composed of impermeable cylindrical particles coated by porous layer is considered. The flow of a fluid is taken parallel to an axis of cylinder and a uniform magnetic field is applied in transverse direction of the flow. The problem is solved by using the cell model technique for the flow through assemblage of cylindrical particles. The solution of the problem has been obtained by using no‐slip condition, continuity of velocity and stresses at interfaces along with Happle's no‐couple stress condition as the boundary conditions. The expressions for the linear velocity, micro‐rotational velocity, flow rate and hydrodynamic permeability of the membrane are achieved in this work. The obtained solution for velocities is used to plot the graph against various transport parameters such as, Hartmann number, coupling parameter, porosity, scaling parameter etc. The effect of these transport parameters on the flow velocity, micro‐rotational velocity, and the hydrodynamic permeability of the membrane have been presented and discussed in this work.

Signal convolution indicates chromatographic pulse flow and open-end flow

Only slices are measured of very long segments of solute molecules that are injected into columns in chromatographic systems. Since the concentration of solute molecules changes during elution as a function of time, the observed signal should be re-constructed for a comparison of experimental results with theory. The influence of response time on the observed signal in high-performance liquid chromatography experiments was investigated in detail using a C-18 column for the measurement of caffeine in pure methanol as eluent. The response function influenced the observed signal by converting the square signal of pulse flow into a chromatographic peak. At faster linear flow rates (LFRs), the response function influenced the observed shape of the chromatographic peak, whereas diffusion dominated at slow LFRs. By convolution of the square signal with the response function, it was possible to predict the shape of the observed signal and chromatographic parameters and to provide an alternative explanation to the van Deemter equation. By using the shape of a known response function and modelling the new theory to data, it was proposed that the injected solute molecules were eluted over long distances through the chromatographic column, distances that are much longer than the physical length of the system.

Abatement of hydrated silica and simultaneous removal of coexisting ions from deep well water by electrocoagulation using an up-flow reactor

The removal of hydrated silica and coexisting ions from groundwater (hydrated silica 42 mg L−1, fluoride 7.3 mg L−1, arsenic 40 μg L−1, sulfate 57 mg L−1, phosphate 0.26 mg L−1, pH = 8.02 and conductivity 605 μS cm-1) by electrocoagulation (EC) was examined. The EC was carried out in a novel up-flow reactor with a six-cell stack, in a serpentine array opened to the atmosphere, using aluminum plates as electrodes. The influence of current density (10 ≤ j ≤ 16 mA cm−2) and mean linear flow rate in the EC reactor (1.16 ≤ u ≤ 4.67 cm s−1), corresponding to retention times between 13.9 ≤ τ ≤ 55.9 s, on the hydrated silica, fluoride, arsenic, sulfate and phosphate removal was investigated. The best removal of hydrated silica based on energy consumption (0.98 KWh m−3) and overall cost of EC (0.274 USD m−3) was obtained at 12 mA cm−2 and u= 2.33 cm s−1, giving a remaining concentration of silica of 7 mg L−1, while the residual concentrations of fluoride (1.4 mg L−1) and arsenic (1.88 μg L−1) met the WHO guidelines in human drinking water. The characterization of the flocs by SEM-EDS, XRF, XRD and FTIR indicated that the coagulant reacts with silica to yield aluminum silicates, fluoride substitutes a hydroxyl group from flocs, while arsenates, sulfates, and phosphates are adsorbed on aluminum aggregates.

Arsenic and hydrated silica removal from groundwater by electrocoagulation using an up-flow reactor in a serpentine array

This paper concerns with the elimination of arsenic and hydrated silica from deep well water, collected form the septentrional area of Guanajuato in Mexico (arsenic 23 μg L−1, hydrated silica 154 mg L−1, sulphate 160 mg L−1, phosphate 0.3 mg L−1, pH 7.5 and conductivity 550 μS cm−1) by electrocoagulation (EC) using an up-flow electrochemical reactor, opened to the atmosphere, with a six-cell stack in a serpentine array. Aluminum plates were used as electrodes. The efficiencies of arsenic and hydrated silica removal at different current densities (4 ≤ j ≤ 7 mA cm-2) and mean linear flow rates (1.2 ≤ u ≤ 4.8 cm s−1) were examined. The best EC was obtained at 7 mA cm-2 and 1.2 cm s−1, which satisfies the WHO guideline for arsenic (< 10 μg L−1) and permits the abatement of hydrated silica, giving values of electrolytic energy consumption and overall cost of EC of 1.64 kW h m-3 and 0.387 USD m-3, respectively. SEM-EDS, FXRD, XRD and FTIR analyses on the flocs revealed that they are structured mainly by aluminosilicates due to the reaction between aluminum and silica. While arsenates, sulfates and phosphates are removed by adsorption on aluminum flocs.

Nonlinear oscillatory fully-developed rarefied gas flow in plane geometry

The nonlinear oscillatory fully developed rarefied gas flow between parallel plates due to an external harmonic force is investigated by the Direct Simulation Monte Carlo (DSMC) method in terms of the parameters characterizing the flow, namely, the gas rarefaction and oscillation parameters, and the force amplitude. The results are in dimensionless form and include the axial velocity, temperature, pressure, wall shear stress, and heat flow vector, as well as the flow rate, cycle-averaged wall shear stress, space-averaged axial heat flow, and pumping power. Even with large force amplitudes, all macroscopic distributions have a sinusoidal pattern with their fundamental frequency being the same with the driving frequency of the external force without the appearance of other harmonics, except of the axial heat flow where the nonlinearities are responsible for generating oscillatory motion containing several harmonics. Nonlinear effects are becoming more significant in highly rarefied flows and low oscillation frequencies. The temperature profile, including the bimodal shape encountered in steady-state flows in the continuum limit, strongly depends on the gas rarefaction and oscillation parameters. The DSMC results have been compared with the corresponding linear oscillatory results, available in the literature, to find out that at small and moderate external forces, the agreement between DSMC and linear flow rates is very good and always remain less than 10%, while at large external forces, the deviation in the flow rate amplitude reaches about 25%. The cycle-averaged oscillatory pumping power is not zero and smaller than the corresponding linear one, following the trend of the flow rates.

Supercritical-Fluid Chromatography On-Chip with Two-Photon-Excited-Fluorescence Detection for High-Speed Chiral Separations.

Herein, we present the first example of microchip-based supercritical-fluid chromatography (SFC). A microfluidic-glass-chip platform with pressure and temperature control for fast and efficient on-column injection is described. This enabled fast and efficient separation of chiral and achiral compounds within seconds and also employed two-photon-excitated-fluorescence detection. Peak shapes were highly regular and symmetric even for linear flow rates over the packed microchip column in a range of up to 20 mm·s-1.

Rapid Synthesis of Poly(methyl methacrylate) Particles with High Molecular Weight by Soap‐Free Emulsion Polymerization Using Water‐in‐Oil Slug Flow

AbstractA flow process for the production of poly(methyl methacrylate) (PMMA) particles is proposed by soap‐free emulsion polymerization using a water‐in‐oil (W/O) slug flow in a microreactor. Thin oil films generated around the dispersed aqueous phase of the W/O slug prevent the prepared particles from adhesion to the microchannel wall, enabling the continuous production of PMMA particles without clogging. The effects of the linear flow rate of the slug flow and the addition of ethanol in the dispersed aqueous phase on the polymerization are evaluated. It is found that increasing the linear flow rate of the slug flow or the addition of ethanol in the dispersed aqueous phase results in PMMA particles with high molecular weight (≈1500 kg mol−1) in 20 min reaction time. It is believed that this process would be a promising way to prepare polymer particles with high molecular weight in a short reaction time.

A lean method for determination of dynamic capacity of a sorbent at multiple sorption of cations

A lean method for calculation of the dynamic capacity of a sorbent as the time function has been suggested that employs a limited amount of experimental data for a sorption process of any duration and allows to obtain an analytical solution by quadrature. To its input parameters belongs a linear flow rate in an adsorber (column) rather than a volume flow rate. This simplifies a reproduction of the sorption process with the target kinetic characteristics at constructively different devices. The method applicability is independent of a kind of sorbent as well as of a number of sorbates in a multicomponent solution. The present paper represents both a theory of the method and its application to a particular case of the concurrent sorption of cations of three heavy metals, Cu(II), Ni(II) and Zn(II), on a natural multifunctional clay-like sorbent glauconite.

Numerical analysis of a Kaplan turbine model during transient operation

Hydropower plants are currently being intensively employed for electrical grid regulation. As a consequence, the frequency of start/stops and load variations is considerably increasing, leading to the operation of hydraulic turbines under improper conditions. During the last years, studies have focused on Francis turbines. The present paper aims to investigate a Kaplan turbine model. The flow through the turbine is modelled during transient operation, from the best efficiency point to a part load operating point, using a moving mesh for the guide vane displacement. The simulations are validated against experimental velocity profiles. A time step sensitivity analysis is performed in order to determine the optimum discretization time. The possibility of using large time steps is explored. The numerically simulated unsteady pressure pulsations on the runner blades are analysed. The influence of the inlet boundary conditions on the accuracy of numerical simulations is studied. The results show that a linear flow rate variation defined during the guide vane closure leads to an overestimation of the turbine head compared to the experimental value due to an overestimation of losses. The second type of boundary conditions, a constant total pressure, results in an underestimation of the flow rate compared to the experimental value due again to an overestimation of the losses.

Adsorption of malachite green in a fixed-bed columns by Thiourea modified poly(acrylonitrile-co-acrylic acid)

Thiourea-modified poly(acrylonitrile-co-acrylic acid) (TU-poly(AN-co-AA)) polymeric adsorbent was synthesized and characterized with Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM) and Zetasizer. Adsorptive removal of cationic malachite green (MG) dye from aqueous solution in a continuous TU-poly(AN-coAA) packed-bed column was studied. The influences of solution pH (2-9), inlet MG concentration (25-80 mg/L), bed depth (4-8 cm) and linear flow rate (1.5-5.0 mL/min) were investigated via assessment of the column breakthrough curves. Low pH and short bed depth, high MG concentration and flow rate led to early breakthrough of MG. According to correlation coefficients (R2) and sum of the squares of the errors (SSE) values, Thomas and Yoon-Nelson dynamic models are more suitable to describe the column experimental data compared to the Bohart-Adams model. TU-poly(AN-co-AA) exhibited effective separation of MG from the liquid phase and displayed high adsorption capacities after five regeneration cycles.

ИЗМЕНЕНИЕ СОСТОЯНИЯ ГЕМОДИНАМИКИ НА ФОНЕ КУРСА СУРФАКТАНТ-ТЕРАПИИ У ПАЦИЕНТОВ С ГОРМОНАЛЬНО-ЗАВИСИМОЙ БРОНХИАЛЬНОЙ АСТМОЙ*

Non-specific hyperresponsiveness of the respiratory tract mucosa makes one of the important pathophysiological mechanisms for asthma development; it is characterized by the increased active response of the efferent system to stimuli. When this occurs, it damages the alveoli surfactant which ensures the viability of local immunity of lung tissue. Chronic respiratory failure induces changes in the cardiovascular system. The course of inhalations with a native surfactant reduces the dependence on inhalation corticosteroid. The objective of the study : to assess the effect of the course of inhalations with surfactant on the cardiovascular system in patients with hormone-dependent asthma. Materials and methods : 15 patients with asthma underwent a 70-day course of inhalation with natural surfactant based on a certain regimen (25 mg per inhalation, 21 inhalations in total) in addition to the basic therapy (inhaled corticosteroids and bronchodilators). On the 1st and 70th days of the surfactant therapy course, oscillometry was performed in order to assess macrohemodynamic parameters. Results. After the course of treatment, pulse pressure was found to increase by 26% compared to the initial level (p <0.05), the cardiac index increased by 16% (p <0.05) and the linear blood flow rate went up by 20% (p <0.05). At the same time, the pulse wave velocity decreased by 15% (p <0.05), while specific vascular resistance went down by 24% (p <0.01). This suggests that clinical remission during surfactant therapy in asthma patients is accompanied by changes in the functional state of the cardiovascular system.

Online Third-Order Liquid Chromatographic Data with Native and Photoinduced Fluorescence Detection for the Quantitation of Organic Pollutants in Environmental Water.

Third-order liquid chromatographic data were generated online for the simultaneous quantitation of six organic environmental pollutants. The employed strategy consists in reducing the linear flow rate at the column outlet. A postcolumn UV reactor and a fluorimetric detector allowed to properly record both photoinduced and native excitation–emission fluorescence matrices (EEPIFMs and EEFMs, respectively). The obtained third-order liquid chromatography data were chemometrically processed with the multivariate curve resolution–alternating least-squares model. The sensitivity of the overall analytical method was enhanced by a very simple solid-phase extraction with C18 membranes, to be able to successfully apply it to natural water samples tested as real matrices. Favorable detection limits for the investigated pollutants, ranging from 0.02 to 0.27 ng mL–1, were attained, with relative prediction errors between 2 and 7%. Since the studied samples contain uncalibrated interferents, the applied strategy achieves the second-order advantage. Implications regarding the potential achievement of the third-order advantage are discussed.

Removal of hydrated silica, fluoride and arsenic from groundwater by electrocoagulation using a continuous reactor with a twelve-cell stack

The simultaneous removal of hydrated silica, fluoride and arsenic from deep well water (hydrated silica 72 mgL−1, fluoride 4.4 mgL−1, arsenic 106.2 μgL−1, sulfate 50 mgL−1, phosphate 0.99 mgL−1, pH = 8.2 and conductivity 659 μScm−1) by electrocoagulation (EC) was investigated. The EC was performed in a continuous electrochemical reactor using aluminum plates as sacrificial anodes coupled directly to a jar test device. The effect of current density (4 ≤ j ≤ 8 mA cm−2) and mean linear flow rates in the EC reactor (0.057 ≤ u ≤ 0.57 cm s−1) on the hydrated silica, fluoride, and arsenic removal efficiencies was analyzed. The abatement of hydrated silica was obtained at 8 mA cm−2 and 0.057 cm s−1, while the residual concentrations of F− and As after the same electrolysis were 0.19 mg L−1 and 9.8 μg L−1, satisfying the WHO guidelines for F− (≤1.5 mg L−1) and As (≤10 μg L−1). Spectroscopic analyses on aluminum flocs revealed that they are predominantly composed of aluminum silicates. Arsenates adsorb on aluminum flocs and fluoride replaces a hydroxyl group from aluminum aggregates.

Sulfate Ions Removal Contained in Water from Abandoned Mines Using an Electrocoagulation Process without Recirculation

Summary This study presents an electrocoagulation-flocculation process to remove the sulphate ions contained in water from abandoned mines in the state of Guanajuato by electrocoagulation (EC) using aluminum as the sacrificial anode in a continuous multi-stage electro-coagulation reactor (Figure 1) with a flocculator-clarifier. The concentration of sulfates was determined by an acid-base equilibrium method and a turbidimetric method at a wavelength of 420 nm, respectively. The best sulfate removal was approximately 58%. Introduction Electrocoagulation is an efficient process to remove sulfates contained in water. This process generates aluminum hydroxides [1,2,3]. The principal reaction on the anode, the electro dissolution of aluminum generates aluminum ions (Al3+); therefore, the aluminum ions are transformed to aluminum hydroxides (Al(OH)3(s)). The sulfate removal mechanism by EC is carried through by adsorption in which aluminum hydroxides flocs entrap an SO4 2- ion [1,2]. Methodology The electrocoagulation was achieved in a continuous multi-stage electrochemical reactor without re-circulation, where the coagulant is produced in a inner way of the reactor. Each resulting solution, after passing EC reactor, was immediately passed to the flocculation and clarification unit (jar test), this solution was mixed at slow speed (30 rpm) for 15 min to form flocs. Then the aggregates were allowed to precipitate in static solution for 1 hr. Subsequently the concentration of sulfate ions contained in the resulting solution was determined by a turbidimetric method. The EC process was performed at current densities of 4, 5 and 6 mA cm–2 at each mean volumetric flow rates. For he characterization of the multi-stage reactor, the theoretical aluminum dose in the EC reactor is that given for CAl3+ = (N) (j*L*MW/z*F*S* ur )*106, [1,2,3]. where j is the current density (A cm–2), L is the length of one channel (cm), MW is the molecular weight of aluminum (26.98 g mol–1), Z is the number of electrons exchanged (z=3), F is the Faraday constant (96485 C mol–1), S is the channel width (cm), ur is the mean linear flow rate (cm s–1), N is the number of channels (N=6), and 106 is a conversion factor use to obtain the aluminum concentration in mg L–1. the energy consumption by electrolysis (Es,vol ). Es,vol which were evaluated by means of Es,vol = (Ecell*I)/(3.6*S*B* ur ), [1,2,3]. Where Es,vol is the energy consumption, I is the current intensity during electrolysis (C s-1), Ecell is the cell potential (J C-1), B is the channel height (cm), and 3.6 is a conversion factor used to obtain Es,vol in units of kWh m-3. Results The water used to achieved this study was collected from the Nopal Mine located in the City of Guanajuato, the characteristics of the water are the following: pH = 8.1, conductivity = 3.72 mS cm-1, sulfate concentration: 4292 mg L-1 The best removal of sulfate ion in terms of energy consumption was obtained at a linear speed of 7.41 cm s-1 with 0.049 kWh m-3 the concentration decreased from 4292 to 1813.2 mg L-1 with a sulfate removal % of 57.7, the energy consumption at a linear speed of 3.7 cm s-1 was of 0.1064 kWh m-3 with a sulfate removal % of 31.2, and finally the energy consumption at a linear speed of 5.55 cm s-1 was of 0.0668 kWh m-3 with a sulfate removal % of 38.2. The concentration of aluminum for each linear speed (3.7, 5.55, 7.42 cm s-1) was of 25.32, 13.39 and 8.92 mg L-1 respectively. Conclusions The best removal of sulfate ion in terms of energy consumption was obtained at a linear speed of 7.41 cm s-1 with 0.049 kWh m-3, where the sulfate ion removal was of 57.7%, having an energy consumption inversely proportional to the linear speed. Using this type reactor is posible to remove a singnificant quatity of sulfates, but not sufficient to meet the standard concentration for a the sulfate NOM-127-SSA1-1994, 400 mg L-1 regulation compliance.

Post mortem CT angiography in fetuses or newborn: Very affordable pump and catheter solution

Abstract This technical note describes a pump and catheter setup that is geared towards performing post mortem computed tomography angiography (PMCTA) examinations in fetal humans. With a voltage controlled very affordable immersion pump and a modified butterfly injection needle, relatively stable linear voltage flow rate relationships can be obtained across flow rates in the range of 30 to 150 ml/min. Flow rates are calculated and compared with actual measurements, whereas practical results suggest a degree of turbulence within the setup used. Practical testing with a fetal pig results in excellent vascular filling. This was subject to considerable partial volume effect, however, so using a micro computed tomography scanner for better quality scans of PMCTA for fetal humans is highly recommended.