In vitro immuno-cytotoxicity of iron evaluated by DNA synthesis of human T lymphocytes stimulated via CD2 and CD3

In previous studies it was demonstrated that the in vitro exposure of human lymphocytes to iron, nickel or cobalt salts causes a significant reduction of lymphocytes expressing CD2 and CD3 surface antigens. Since both molecules are involved in T lymphocyte activation, these studies suggest that the above metals might affect T-cell activation and proliferation. Thus a method was developed for the stimulation of lymphocytes in which both CD2 and CD3 molecules were triggered simultaneously. For this purpose an anti-CD3 monoclonal antibody (mAb) was chemically bound to human erythrocytes (HE), forming HECD3 conjugates, which were used for lymphocyte stimulation. In this work the effects of iron on lymphocyte proliferation was studied, following stimulation via CD2 and CD3, in order to evaluate the immuno-cytotoxicity of iron. Increasing concentrations (5×10^-3 m-10² m) of iron citrate (Fe-citrate) showed that the higher concentration range (10 m-10² m) caused moderate inhibitions of lymphocyte DNA synthesis (ranging between 18.3% and 78.6%). Furthermore the presence of monocytes in culture did not interfere in the inhibitory effect of Fe-citrate. Phenotypic characterisation of DNA-synthesizing cells in the presence of Fe-citrate showed that the CD8⁺ (suppressor/cytotoxic) subset was the most reduced one. This study showed that iron inhibited T lymphocyte proliferation, particularly the suppressor/cytotoxic cells, suggesting that the presence of high levels of iron in in vivo situations can cause immunosuppression and, consequently, contribute to the onset of opportunistic infections and tumours.     

Free vibrations of a circular plate with attached concentrated mass,spring and dashpot

Summary The natural vibrations of a circular plate with attached concentrated mass, spring and dashpot have been obtained by means ofYoung's analysis [1]. The results are presented in terms of eigen-functions of the plate alone. The case of a plate carrying two masses and resting on elastic foundation has also been studied. Some particular cases have been deduced.

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Zusammenfassung Die Eigenschwingungen einer Kreisplatte mit lokal befestigter Einzelmasse, Feder und Dämpfer werden nach derYoungschen Methode [1] ermittelt. Die Ergebnisse werden als Entwicklung nach den Eigenfunktionen der reinen Plattenschwingung dargestellt. Der Fall der elastisch gebetteten Platte mit zwei Einzelmassen wird ebenfalls studiert. Einige Sonderfälle werden hergeleitet.

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Nomenclature a radius of circular plate - h plate thickness - k ₁ spring constant - k _c generalized spring constant - modulus of elastic foundation - decay constant - c dashpot strength - D , flexural rigidity of plate - E Young's modulus - v Poisson's ratio - p natural frequency of plate alone - natural frequency of composite system - w deflection mode of plate - r, cylindrical coordinates - mass density - r - (l/D)^1/4 - - - F _m ,L _m ,G _m ,M _m unknown constants With 5 Figures     

Transfer in Metallic Cadmium of the Impurity 115m In Atoms Formed at Radiation Capture of Neutrons

A study was made of transfer of the impurity ^115m In atoms formed at radiation capture of neutronsand subsequent ^- decay [¹¹⁴Cd(n')¹¹⁵Cd ^- decay] in irradiated metallic cadmium (fluence 4.5×1019 neutron cm^-2). It was shown that the transfer rate of ^115m In depends on the degree of defectivenessof the structure yielded by irradiation, tends to decrease during post-radiation annealing of metallic cadmium. The parameters of indium diffusion in metallic cadmium after annealing of the radiation-induced defectswere estimated at E _a = 12.56 kJ mol^-1, D ₀ = 3.18 ×10^-9 cm² s^-1.     

Presence of a biomaterial implant facilitates induction of experimental infective endocarditis due to streptococci and staphylococci

Infective endocarditis (IE) usually is studied using animals with catheters inserted into the heart, which causes formation of platelet-fibrin thrombi (vegetations, VGs). We used two rabbit models to study the respective roles of the catheter and the VGs in the development of IE. The influence of the catheter was studied by either removing the catheter before bacterial challenge, or leaving the catheter in place. In all cases, removal of the catheter caused a strong decrease in the frequency of IE. The presence of the catheter stimulated population increase of streptococci within 4 h after challenge. As most catheters were sterile 4 h after challenge, they did not serve as a reservoir of bacteria. To study the requirement of a preformed VG catheters were inserted either 24 h or 30 min before bacterial challenge. In the former model VGs were present, in the latter VGs were not yet formed when bacteria were injected. The frequencies of IE due to 2 S. sanguis and 2 S.epidermidis strains in the 24 h model or 30 min model were similar, indicating that a preformed VG is not necessary for development of IE. Five coagulase-negative stains were shown to vary in their capacity to cause IE in the 30 min model. Variation was not caused by differences in early adhesion or colonization of the aortic valve, but reflects differences in persistence after initial colonization. Like in the 24 h model, persistence of the bacteria was greatly enhanced by the continuous presence of the catheter. Possible mechanisms of the infection-potentiating effect of the catheters are discussed.     

An investigation of microbial adhesion to natural and synthetic polysaccharide-based films and its relationship with the surface energy components

In recent years, polysaccharide-based films have been developed for many applications. Some of these are in the pharmaceutical industry, where the adhesion of microorganisms to surfaces is a concern. After adhesion of a microorganism to a solid surface has taken place, the subsequent biofilm formed can act as a vehicle for spreading infections. The aim of this study is to compare the bacterial adhesion of E. coli and S. aureus from a contaminated solid model (Tryptone Soya Agar) to a range of polysaccharide-based films. These polysaccharide-based films consist of different natural starches (potato, cassava, wheat, pea and rice) and synthetic polymers hydroxyl-propyl cellulose (HPC) and carboxyl methyl cellulose (CMC)). The surface energy parameters of the films were calculated from the contact angle measurements by the sessile drop method. Apolar and polar liquids (water, formamide and hexadecane) and the Lifshitz-Van der Waals/acid-base (LW/AB) approach were used according to the method of Van Oss, Chaundhury and Good. The surface properties of the films were also correlated to the microbial adhesion. This indicated that, for both E. coli and S. aureus, the surface roughness did not affect the microbial adhesion. Only had any correlation with the microbial adhesion and was almost constant for all the various polysaccharide films tested. In addition, the electron—donor properties of the materials, exhibited via , were positively correlated with the adhesion of S. aureus but not with E. coli. This was in agreement with the results of the MATS (Microbial Adhesion To Solvents) test performed on the two bacteria. This revealed that only S. aureus presented an electron—acceptor characteristic.     

Eine ähnliche Lösung der kompressiblen laminaren Grenzschichtgleichungen für eine Düsenströmung

Zusammenfassung Es wird eine neue ähnliche Lösung der Differentialgleichungen für kompressible laminare Grenzschichten angegeben. Unter der einschränkenden VoraussetzungPr=1, T und wärmeisolierter Wand können die Grenzschichtgleichungen durch eine Koordinatentransformation nachLi undNagamatsu [6] in drei gewöhnliche Differentialgleichungen umgeformt werden, einer für die AußenströmungM ^*(x), eine für den MaßstabsfaktorN(x) der Stromfunktion und eine für die ähnliche Geschwindigkeitsverteilung in der Grenzschicht. Die Lösungen können in geschlossener Form angegeben werden, wenn der Isentropenexponent =1,4 (bei Luft) gesetzt wird. Die erhalteneM ^*(x)-Verteilung entspricht der in einerLaval-Düse. Die nichttransformierten Geschwindigkeitsprofile die Verdrängungsdicke und der örtliche Reibungsbeiwert werden ebenfalls in geschlossener Form für die Düsenströmung dargestellt.

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Summary A new similar solution of the differential equations for compressible laminar boundary layers is presented. Assuming the wall to the insulated against loss of heat, introducing the restrictionsPr=1 and T and using a coordinate transformation due toLi andNagamatsu [6] the equations may be reduced to three ordinary differential equations: one for the outer flowM ^*(x), one for the scale factorN(x) of the stream function and one for the similar velocity distribution in the boundary layer. Solution can be given in closed form provided the isentropic exponent =1,4 (for air) is chosen. TheM ^*(x) distribution thus obtained corresponds to that in aLaval nozzle. The non-transformed velocity profile, the displacement thickness and the local coefficient of friction for the flow in a nozzle are also given.

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Die wichtigsten Bezeichnungen x Koordinate längs der Strömungsberandung - y Koordinate senkrecht zur Strömungsberandung - Grenzschichtdicke - u Geschwindigkeit in x-Richtung - v Geschwindigkeit in y-Richtung - a Schallgeschwindigkeit - M MacH-Zahl - a^* Kritische Schallgeschwindigkeit - M^* Kritische Mach-Zahl - p Statiseher Druck - T Absolute Temperatur - Dichte - Dynamische Zähigkeit - v Kinematisehe Ziihigkeit - Wärmeleitzahl - R^* Gaskonstante - c_p Spezifische Wärme bei konstantem Druck - c_v Spezifische Wärme bei kostantem Volumen - x Isentropenexponent - Schubspannung - c_f Örtlicher Reibungsbeiwert Indices w Auf die Wand bezogen - Auf den Rand der Grenzschicht bezogen - O Auf den Ruhezustand bezogen Mit 6 Textabbildungen     

Temperature Dependence of the Volumetric Properties of Binary Mixtures Containing Polyethers and 1-Propanol

Excess molar volumes (V ^E _m ) were measured at 288.15, 298.15, and 308.15 K and atmospheric pressure as a function of composition with a continuous dilution dilatometer for the binary mixtures of 1-propanol [CH₃CH₂CH₂OH] with glymes [CH₃O(CH₂CH₂O) _m CH₃, m=1,2,3, and 4]. With these results and other thermodynamic data from the literature, the following mixing quantities have been reported over the complete range of concentration or at equimolar concentration: , volume expansivity; ^E , excess volume expansivity; (V ^E _m /T) _P , and (H ^E /P) _T at 298.15 K. The Prigogine–Flory–Patterson theory (PFP) of liquid mixtures has been applied to estimate interaction, free-volume, and internal-pressure contributions to V ^E _m and to estimate the different mixing quantities for the mixtures. The calculated values using the PFP theory were then compared at 298.15 K with the experimentally obtained results. The PFP theory predicts excess volume V ^E _m values rather well, while the calculated value of (V ^E _m /T) _P and (H ^E /P) _T by using the Flory theory show general variation with the chain length of the glyme. The (V ^E _m /T) _P and (H ^E /P) _T show deviations between theoretical and experimental values that are slightly larger in systems with lower glyme.     

Determination of the Thermal Diffusivity of Edible Films

One of the most important factors in the preparation of edible films regards the choice of ingredients. Edible films are commonly prepared with single or mixed high-molecular-weight compounds like proteins and gums. In the present work, protein and gum-based edible films were prepared and their thermal diffusivity determined by photoacoustics. The films were prepared with different concentrations of four basic ingredients: whey protein concentrate, mesquite gum, sodium alginate, and -carrageenan. In single-component films, the highest thermal diffusivity was found in mesquite gum (1.97×10^–7m²s^–1), followed by sodium alginate, whey protein concentrate, and -carrageenan samples. In composed films, the highest thermal diffusivity was obtained in a ternary film made of mesquite gum, whey protein concentrate, and sodium alginate in identical parts (5.20×10^–7m²s^–1).     

Adhesion and growth of vascular smooth muscle cells in cultures on bioactive RGD peptide-carrying polylactides

The surface of poly(l-lactide) (PLLA) films deposited on glass coverslips was modified with poly(dl-lactide) (PDLLA), or 1:4 mixtures of PDLLA and PDLLA-b-PEO block copolymers, in which either none, 5% or 20% of the copolymer molecules carried a synthetic extracellular matrix-derived ligand for integrin adhesion receptors, the GRGDSG oligopeptide, attached to the end of the PEO chain. The materials, perspective for vascular tissue engineering, were seeded with rat aortic smooth muscle cells (11,000 cells/cm²) and the adhesion, spreading, DNA synthesis and proliferation of these cells was followed on inert and bioactive surfaces. In 24-h-old cultures in serum-supplemented media, the number of cells adhering to the PDLLA-b-PEO copolymer was almost eight times lower than that on the control PDLLA surface. On the surfaces containing 5% and 20% GRGDSG-PEO-b-PDLLA copolymer, the number of cells increased 6- and 3-fold respectively, compared to the PDLLA-b-PEO copolymer alone. On PDLLA-b-PEO copolymer alone, the cells were typically round and non-spread, whereas on GRGDSG-modified surfaces the cell spreading areas approached those found on PDLLA, reaching values of 991 μm² and 611 μm² for 5% and 20% GRGDSG respectively, compared to 958 μm² for PDLLA. The cells on GRGDSG-grafted copolymers were able to form vinculin-containing focal adhesion plaques, to synthesize DNA and even proliferate in a serum-free medium, which indicates specific binding to the GRGDSG sequences through their adhesion receptors.     

A new rabbit model of implant-related biofilm infection: development and evaluation

This study is to establish a rabbit model for human prosthetic joint infection and biofilm formation. Thirty-two healthy adult rabbits were randomly divided into four groups and implanted with stainless steel screws and ultra-high molecular weight polyethylene (UHMWPE) washers in the non-articular surface of the femoral lateral condyle of the right hind knees. The rabbit knee joints were inoculated with 1 mL saline containing 0, 10², 10³, 10⁴ CFU of Staphylococcus epidermidis (S. epidermidis) isolated from the patient with total knee arthroplasty (TKA) infection, respectively. On the 14th postoperative day, the UHMWPE washers from the optimal 10³ CFU group were further examined. The SEM examination showed a typical biofilm construction that circular S. epidermidis were embedded in a mucous-like matrix. In addition, the LCSM examination showed that the biofilm consisted of the polysaccharide stained bright green fluorescence and S. epidermidis radiating red fluorescence. Thus, we successfully create a rabbit model for prosthetic joint infection and biofilm formation, which should be valuable for biofilm studies.     

A study of mechanical configuration optimisation in micro-systems

This paper shows that there are three main categories of factors that make the optimum mechanical design of micro-systems different from macro-systems: scale effects, a limited range of materials, and a limited range of production processes. The combined effect of these factors can make the optimum configuration of a micro-system potentially very different from that of the same system on a macro-scale. In particular, the use of flexible elements for hinges is much more feasible and desirable on a micro-scale.Notation a acceleration (m/s²) - A cross-sectional area (m²) - B magnetic flux [wb/m²] - b width [m] - C constant - d depth [m] - D drag [N] - E Young's modulus [N/m²] - E*= - f resonant frequency [Hz] - F _D drive force [N] - F _E electrostatic pulling force [N] - F emmisivity function - F _G geometric view factor - g gravitational constant [m/s²] - h _c convention heat transfer coefficient [W/m²K] - h height [m] - i current [A] - I _A second moment of area [m⁴] - I _I moment of inertia [kg m²] - J polar second moment of area [m⁴] - k stiffness [N/m] - K thermal conductivity [W/m K] - l length [m] - m mass [kg] - M moment [N m] - P load [N] - P _H Hertz contact pressure [N/m²] - P _C cylinder pressure [N/m²] - q heat transfer rate [W] - R, r radius [m] - Re Reynolds number - T, t temperature [K] - T _A atomic friction torque [N m] - T _D drive torque [N m] - T _F Coulomb friction torque [N m] - T _I inertial resistive torque [N m] - u velocity [m/s] - mean velocity [m/s] - V volume [m³] - V _e voltage [V] - x distance between electrodes [m] - y maximum distance to neutral axis [m] - angular acceleration [rad/s²] - _d thermal diffusivity [1/K] - rolling friction factor - P pressure difference [N/m²] - ₀ dialectric constant [F/m] - strain - dynamic viscosity [Pa s] - scale factor - _S coefficient of sliding friction - _R coefficient of rolling friction - _{1, 2} Poisson's ratio - density (kg/m³) - temperature rise [°C] - _B bending stress [N/m²] - _y yield strength [N/m²] - shear stress [N/m²] - reliability constant     

Stress-strain rate relations for high-temperature deformation of two-phase Al-Cu alloys

Al-Cu alloys containing 6, 11, 17, 24 and 33 wt% Cu, annealed for 0.5–100 h, were deformed by the differential strain-rate test technique over a strain-rate range of 4×10^–6 to 3×10^–2s^–1 at temperatures ranging from 460–540°C. Superplastic behaviour, with strain-rate sensitivity, m0.5, and activation energy, Q=171.5 kJ mol^–1, is shown by the Al-24Cu and Al-33Cu alloys at lower strain rates and higher temperatures. All the alloys show m0.20 at higher strain rates, but the average activation energy for deformation of the Al-6Cu, Al-11Cu, and Al-17Cu alloys is evaluated to be 480.7 kJ mol^–1, in contrast to a lower value of 211 kJ mol^–1 for the Al-24Cu and Al-33Cu alloys. Instead of grain size, the mean free path between particles is suggested to be a more appropriate microstructural parameter for the constitutive relationship for deformation of the Al-Cu alloys.     

Energy dependence of the effective mass in liquid3He

The striking behavior of the specific heat of liquid³He as function of temperature at low temperatures requires the effective massm* to change rapidly with temperature; this can be translated into a rapid variation with energy,m*/m dropping from itsE=0 value to 1 over the temperature range 0.5 K. We explore this effect in a model in which the enhancement of the effective mass is due to coupling to spin fluctuations. At very lowT50 mK, the variation in specific heat results fromT ³ lnT terms. The free energy, on the other hand, does not containT ² lnT terms in its dependence on the magnetic field, implying that the susceptibility, which is essentiallym*/(1+F ₀ ^a ), also does not have such logarithmic terms. Consequently, ifm* varies with energy, so mustF ₀ ^a , so as to leave the susceptibility free of this rapid variation. The rough constancy ofm*/(1+F ₀ ^a ) seems empirically to hold to higher energies and temperatures. Ifm*/m drops, with increasing energy, to unity, the spin-fluctuation theory, which is described in terms of Landau parameters at the Fermi surface, goes over into the paramagnon theory. The rapid change with energy of the effective interactions can be understood within the framework of response theory as a shaking off of the relevant collective modes with increasing frequency of the imposed oscillations. The changes in effective interactions have consequences for the interpretation of experiments involving inelastic neutron scattering from liquid³He.Also State University of New York, Stony Brook, New York. Supported in part by U.S. D.O.E. Contract DE-AC02-76ER13001.Also University of Illinois at Urbana—Champaign. Supported in part by U.S. NSF Grant DMR 81-21273.     

Electrochemical ZrO2 and Al2O3 coatings on SiC substrates

SiC was electrochemically coated with ZrO₂ and with Al₂O₃ from 0.1 m aqueous solutions of metal-nitrate-hydrates with ethanol added. Amorphous zirconia and alumina coatings were formed with current densities from 10 to 70 mA cm^–2, and deposition durations of 1–60 min. The as-deposited coatings contained microcracks caused by drying shrinkage. Sintering of zirconia at 900 °C for 1 h and of alumina at 1200 °C for 2 h in air was accompanied by crystallization to a mixture of tetragonal and monoclinic phases in the former and to -alumina in the latter. The absence of intermediate phases between the coatings and the substrates and the good adherence of the sintered coatings indicate the high-temperature stability of these coatings.     

Anomalous temperature dependence ofD andT 2 for dilute solutions of3He in solid4He

Results of measurements of the spin diffusion coefficientD and NMR relaxation timesT ₁,T ₂, and T_1p are presented for a range of fractional³He concentrations 1 × 10^–4x ₃2.5 × 10^–3 in solid⁴He at molar volumes 19.85V _m21.0 cm³ and temperatures 0.4<T<2 K in both hcp and bcc phases. We observe a minimumD(T) atx ₃=5×10^–4, which is interpreted in terms of a transition from coherent impuriton motion to thermally activated diffusion. ForT<0.8 K, (lnD)/(lnV _m)=60±8. TheT ₂ measurements show a minimum as a function of temperature forx ₃10^–3. TheT ₂ (T) andT ₁ (T) results yield values for activation energy and tunneling frequency of vacancies in these dilute solutions. Forx ₃=5×10^–4 andT 0.5 K,T ₂ (V _m) is anomalous.T ₁ measurements at the same concentration indicate there is an important contribution to the spectral density of dipole field fluctuations in the kHz region.Financial support provided for apparatus, materials, and a research studentship (ARA) by the Science Research Council.     

Structure parameters of metal-fiber heat pipe wicks

The results of an experimental investigation of local and average values of permeability and effective pore diameter for metal-fiber wicks, using a laser-Doppler velocity measurement, are presented and discussed.Notation K permeability coefficient, m² - V filtration rate, m/sec - viscosity, N·sec/m² - dp/dx pressure gradient - rms deviation - f_i probability density distribution,m^–1 - D pore diameter,m - E excess - A asymmetry The 50-Year Anniversary of the Great October Socialist Revolution Kiev Polytechnic Institute.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 35, No. 5, pp. 777–781, November, 1978.     

Micro-yielding in a precipitation hardening Cu 1.81 wt % Be 0.28 wt % Co alloy

The microstrain characteristics of a polycrystalline Cu 1.81 wt % Be 0.28 wt % Co precipitation hardening alloy have been determined for various precipitate conditions. The friction stress derived from measurements of closed hysteresis loops was found to remain constant ( 3 MN m^–2) for all the conditions investigated. In contrast, the microscopic yield stress (MYS) remained constant (18 to 24 MN m^–2) for most ageing conditions, but increased significantly (to 48 to 64 MN m^–2) for conditions associated with a high G.P. zone or precipitate density.     

An apparatus for measuring the thermal conductivity and diffusivity of solid materials

An apparatus is described for measuring the thermal conductivity and diffusivity on small specimens of solid materials; also the results are shown which have been obtained for refractive high-alumina concrete by such measurements.Notation thermal conductivity at the mean temperature of specimens, W/m· °C - Q power of the central heater, W - F cross section area of a specimen, m² - t_1,2 temperature drop across the specimens, °C - ₁, ₂ difference in heights between the thermocouple beads, center-to-center, in the first and in the second specimen respectively, m - t temperature, °C - time coordinate, min - d₁= (d_1u+d_1l )/2 mean distance between specimen contact plane and nearest thermocouple beads, for the upper and lower specimen, m - d₂= (d_2u+d_2l )/2 mean distance between specimen contact plane and farthest thermocouple beads, for the upper and lower specimen, m - dt(d₁,)/d rate of temperature rise at section d₁ of the specimen at time, °C/h - t=t₁+t₂ sum of temperature drops in the specimens at time, °C - m heating rate, h^–1 - a thermal diffusivity of specimens, referred to their mean temperature, m²/h - =m/a, m^–1 b=¦(t_u–t_l)/t_u¦ heating nonuniformity factor Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 22, No. 6, pp. 1049–1054, June, 1972.     

Influence lines for bending under a ring load of a free shell,a shell embedded in a soft medium and a shell containing a soft core

Summary Theoretical expressions for stresses and displacements have been derived for bending under a ring load of a free shell, a shell embedded in a soft medium, and a shell containing a soft core. Numerical work has been done for typical cases with anElliot 803 Digital Computer and influence lines are drawn therefrom.

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Einflußlinien für die Biegung einer freien Schale, einer Schale in einer weichen Bettung und einer Schale mit weichem Kern

Zusammenfassung Für die Biegung einer freien Schale, einer weich gebetteten Schale und einer Schale mit weichem Kern unter einer Ringlast werden Ausdrücke für die Spannungen und Verschiebungen hergeleitet. Die Ergebnisse wurden für einige typische Fälle mit einem DigitalrechnerElliot 803 numerisch ausgewertet. Die sich ergebenden Einflußlinien wurden graphisch dargestellt.

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Nomenclature A (),B () Functions of - a, t Mean radius and thickness of the shell - E _S , _S Young's modulus andPoisson's ratio of the shell - G _c , _c Shear modulus andPoisson's ratio of the casting or core - I ₀ (r),I ₁ (r) ModifiedBessel functions of the first kind and order zero and one respectively - K ₀ (r),K ₁ (r) ModifiedBessel functions of the second kind and order zero and one respectively - p Ring load, lb/in - U, W Displacement components in the casing or core in thez andr direction - u, w Displacement components of a middle surface point in the shell - _r , _rz Radial and shearing stress components - Independent variable of infinite integrals - k [3(1–S ²)a ²/t ²]^1/4 With 13 Figures     

Determination of structural parameters of metallic foams from permeametry measurements

An experimental technique, permeametry, is carried out in order to determine the dynamic specific surface area and the tortuosity of three nickel foams. A capillary-type model allows calculation of these structural parameters from pressure-drop measurements. Studying pressure drops of two different flow configurations also allows quantification of a third parameter due to the anisotropy of the material structure. The values of the parameters determined throughout this work are compared with those obtained in previous works using different experimental methods.Nomenclature A experimental coefficient defined by Equation 3 (Pa sm^–2) - A _vd dynamic specific surface area, related to volume of solid (m^–1) - A _ve specific surface area, related to volume of porous medium (m^–1) - B experimental coefficient defined by Equation 4 (Pas²m^–3) - Cr precision criterion - D hydraulic diameter of the cell (m) - d equivalent pore diameter (m) - f friction factor - H bed height or thickness of porous material (m) - J coefficient defined by Equation 8 (m^–1) - K coefficient defined by Equation 9 (m^–2) - l pore length (m) - mre mean relative error - n+1 number of pressure taps - P pressure drop (Pa) - R anisotropy factor or shape anisotropy ratio - Re superficial Reynolds number, Re = U _o d/u - Re_i interstitial Reynolds number, Re _i = U _o d/() - T tortuosity - U _o superficial velocity (m s^–1) - porosity - dynamic viscosity (Pa s) - fluid density (kg m^–3)