pH Curves Research Articles

Effects of calcium-magnesium carbonate and calcium-magnesium hydroxide as supplemental sources of magnesium on microbial fermentation in a dual-flow continuous culture.

Supplemental sources of Mg can also aid in ruminal pH regulation due to their alkaline properties. Magnesium oxide (MgO) is the most common source of Mg for ruminants and can help controlling ruminal pH; however, the alkaline potential of other sources of Mg has not been evaluated. We aimed to evaluate the inclusion of calcium–magnesium carbonate (CaMg(CO3)2) and calcium–magnesium hydroxide (CaMg(OH)4) alone or in combination as supplemental sources of Mg in corn silage-based diets and its impact on ruminal microbial fermentation. We hypothesized that inclusion of CaMg(OH)4 would allow for ruminal fermentation conditions resulting in a greater pH compared to the inclusion of CaMg(CO3)2. Four treatments were defined by the supplemental source of Mg in the diet: 1) Control (100% MgO, plus sodium sesquicarbonate as a buffer); 2) CO3 [100% CaMg(CO3)2]; 3) OH [100% CaMg(OH)4]; and 4) CO3/OH [50% Mg from CaMg(CO3)2, 50% Mg from CaMg(OH)4]. Nutrient concentration was held constant across treatments (16% CP, 30% NDF, 1.66 Mcal NEl/kg, 0.67% Ca, and 0.21% Mg). Four fermenters were used in a 4 × 4 Latin square design with four periods of 10 d each. Samples were collected for analyses of nutrient digestibility, soluble Mg, VFA, and NH3, while pH was measured at 0, 1, 2, 4, 6, 8, and 10 h post morning feeding to estimate % time when pH was below 6 (pH-B6) and area under the pH curve for pH below 6.0 (pH-AUC). Bacteria pellets were harvested for 15N analysis and estimates of N metabolism. Treatment effects were analyzed with the mixed procedure of SAS, while effects of using either CaMg(CO3)2 or CaMg(OH)4 as Mg source in comparison to Control treatment were evaluated by orthogonal contrasts. Similar pH-related variables were observed for Control, OH, and CO3/OH treatments, which had smaller pH-AUC and pH-B6 than CO3 (P ≤ 0.01). Butyrate molar proportion was greater in Control and CO3/OH than in CO3 and OH (P = 0.04). Orthogonal contrasts showed lower flow of bacterial N (P = 0.04), lower butyrate molar proportion (P = 0.08) and greater pH-AUC (P = 0.05) for diets with CaMg(CO3)2 in comparison with the Control. Concentration of soluble Mg in ruminal fluid (P = 0.73) and nutrient digestibility (P ≥ 0.52) were similar across treatments. Under the conditions of this experiment, using CaMg(OH)4 alone or combined with CaMg(CO3)2 allowed for a less acidic ruminal fermentation pattern than a diet with only CaMg(CO3)2.

Acid washing of incineration bottom ash of municipal solid waste: Effects of pH on removal and leaching of heavy metals

This study systematically investigated the acid washing of incineration bottom ash (IBA) of municipal solid waste, focusing on the removal and leaching of heavy metals (Pb, Zn, Cr, Cd, Cu, and Ni), as well as their pH-dependent behavior. A series of small-scale laboratory acid washing tests with different nitric acid concentrations and washing periods were conducted. The concentrations of metals in the washing water were measured to evaluate the metal removal efficiency. Then, one stage batch leaching test was conducted for washed IBA to evaluate the leaching reduction efficiency of washing. The results showed that the maximum metal removal efficiencies for Zn, Cu, and Ni (62–76%) were higher than those for Pb, Cr, and Cd (17–25%), which were reached at the highest acid addition for most of the metals. Increasing the washing period did not always increase the metal removal efficiency. The maximum leaching reduction efficiencies were higher for Zn, Cr, and Cu (93–98%) than those for Pb, Ni, and Cd (73–79%). Both washing and leaching processes showed a similar metal concentration-pH profile for each metal. For Pb, Zn, Cr, and Cd, the metal concentration-pH profile generally followed the metal hydroxide solubility versus pH curves. For Cu and Ni, the concentration of metal decreased with the increasing pH first and then kept at a stable concentration higher than the solubility of the hydroxide, indicating that Cu and Ni in the IBA washing water and leachates did not exist dominantly as their hydroxides.

Geometric Hermite interpolation by a family of spatial algebraic–trigonometric PH curves

This paper proposes to define a family of spatial algebraic–trigonometric Pythagorean Hodograph (ATPH) curves by integrals of scaled unit tangent vector fields which are originally defined as sphere curves. The obtained ATPH curves have only polynomial parametric speeds but the curves can be employed to represent several typical non-polynomial curves without rational form. A simple algorithm for geometric Hermite interpolation by the proposed spatial ATPH curves without or with arc length constraint has been given. Given two boundary points and two unit tangents at the points, possibly with a prescribed arc length, a unique interpolating ATPH curve can be obtained by solving a simple linear system.

Non-monotonic behavior of weak-polyelectrolytes adsorption on a cationic surface: A Monte Carlo simulation study

In this work, the weak polyelectrolyte (PE) adsorption on a strong cationic surface is studied with constant pH Monte Carlo simulations using a coarse-grained model. When a large number of PE chains is added to the system, the PE adsorbed amount vs pH curve exhibits a non-monotonic behavior, with the appearance of a maximum close to the intrinsic pKa0-value of the PE titratable groups. The apparent pKa-value of the PE chains shows a non-trivial tendency depending on the pH-value and the surface coverage degree. In increasing the pH-value, the small anions that accompany the cationic surface are replaced by PE chains and small cations. For pH>pKa0+1, an evident charge reversion of surface is observed. These results are explained analyzing the interplay between the attractive and repulsion electrostatic interactions between the different components of the system (inter- and intra-charged monomers of PE chains, the strong cationic surface and small ions) and their effects on the PE chain ionization.

Solubility determination and thermodynamic modelling of solid-liquid equilibria in the (NaCl + NaBO2 + Na2B4O7 + H2O) system at 298.15 K

The solubility corresponding solution physicochemical properties (densities, refractive indices and pH) in the quaternary system (NaCl + NaBO2 + Na2B4O7 + H2O) were investigated at 298.15 K by the isothermal dissolution equilibrium method. The dry-salt phase diagram, water content diagram, refractive index diagram and pH diagram were drawn. There are four crystallization fields corresponding to NaCl, NaBO2·4H2O, Na2B4O7·10H2O, NaCl·NaBO2·2H2O, five univariant curves and two invariant points in the phase diagram of the quaternary system. The solubility, concentrations of boron species B(OH)3, B(OH)4−, B3O3(OH)4−, B4O5(OH)42− and OH− in the system were calculated using the Pitzer model. The variation trends for calculated solubility curves and pH curves are consistent with the experimental results. The distributions of different boron species were obtained in the mixed borate solution. The distributions of four boron species were obtained in the mixed borate solution. The main boron species in the mixed borate solution are B(OH)4− and B4O5(OH)42−. The mole fractions of the four boron species are mainly affected by m(B) in the solution but less by m(Cl−).

A primer on tissue pH and local anesthetic potency.

The relationship between pH, pKa, and degree of local anesthetic ionization is quantified by the Henderson-Hasselbalch equation. As presented in standard textbooks, the effect of pH on the degree of ionization of any particular local anesthetic is not immediately clear due to the x-axis displaying pH - pKa, which requires conversion to pH, based on the pKa for each local anesthetic, a complex process. We present a graphical solution that clarifies the interrelationships between pH, pKa, and degree of ionization by plotting pKa on the x-axis versus the percentage of unionized local anesthetic on the y-axis. The vertical intercept from the x-axis to the pH curves allows rapid and accurate estimation of the degree of ionization of any local anesthetic of known pKa.

Shape analysis of planar PH curves with the Gauss–Legendre control polygons

Kim and Moon (2017) have recently proposed rectifying control polygons as an alternative to Bézier control polygons and a way of controlling planar PH curves by the rectifying control polygons. While a Bézier control polygon determines a unique polynomial curve, a rectifying control polygon gives a multitude of PH curves. This multiplicity of PH curves naturally raises the selection problem of the “best” PH curves, which is the main topic of this paper.To resolve the problem, we first classify PH curves of degree 2n+1 into 2n subclasses by defining the types of PH curves, and propose the absolute hodograph winding number as a topological index to characterize the topological behavior of PH curves in shape. We present a lower bound of the topological index of a PH curve which is given solely by its type, and prove the uniqueness of the best PH curve by exploiting it. The existence theorems are also proved for cubic and quintic PH curves. Finally, we propose a selection rule of the best PH curve only based on its type.

The effect of sodium octadecyl sulfate on the electrokinetic potential of metal oxides

Dispersions of hematite, titania, and alumina containing sodium octadecyl sulfate have been studied. Increasing concentrations of the surfactant induced a shift in the IEP to low pH, and at sufficiently high surfactant concentrations, the ζ potential assumed negative values over the entire pH range. The ζ potential vs. pH curves obtained in sodium octadecyl sulfate - metal oxide systems belong to the type I electrokinetic curves described in our previous study, that is, these curves do not show a maximum at nearly neutral pH. Our results confirm that in long-chained sodium alkyl sulfates type I electrokinetic curves are observed, as opposed to the type II electrokinetic curves (with a maximum at nearly neutral pH), which are observed in short-chained sodium alkyl sulfates.

Effect of ferrolysis and organic matter accumulation on chromate adsorption characteristics of an Oxisol-derived paddy soil

How paddy cultivation influences the adsorption isotherms, envelopes, and the kinetics of hexavalent chromate (Cr(VI)) on Fe (hydro)oxide-rich paddy soil, as well as the mechanisms involved, remain largely unaddressed. To this end, the Cr(VI) adsorption characteristics on a paddy soil, in comparison with its parent upland Oxisol, were studied. The results showed that Cr(VI) adsorption capacities (Qmad) were higher in the surface Oxisol than in the same layer of paddy soil. The Qmad increased by 18.0% and 41.3% after removal of soil organic matter (SOM) from the surface Oxisol and paddy soil layers, respectively, indicating that Cr(VI) adsorption was considerably inhibited by SOM. The adsorption and desorption isotherms demonstrated that non-electrostatic adsorption was mainly responsible for Cr(VI) adsorption, accounting for 59.37%–83.42% of Cr(VI) adsorption capacities. The negative shift of the zeta potential–pH curves with Cr(VI) loading further corroborated the finding that non-electrostatic adsorption is largely responsible for Cr(VI) retention. Cr(VI) adsorption at equilibrium, obtained by the stirred flow chamber technique, and the free Fe (hydro)oxides (Fed) contents were in the same order, suggesting that Fed are the main adsorbents for Cr(VI). Therefore, paddy cultivation has had a profound impact on the electrochemical properties of the Oxisol and on subsequent Cr(VI) adsorption characteristics.

Modeling reticular and ventral ruminal pH of lactating dairy cows using ingestion and rumination behavior

The prevention and control of metabolic and digestive diseases is an enormous challenge in dairy farming. Subacute ruminal acidosis (SARA) is assumed to be the most severe feed-related disorder and it impairs both animal health and economic efficiency. Currently, ruminal pH as well as variables derived from the daily pH curve are the main indicators for SARA. The objective of this study was to explain the daily pH course in the ventral rumen and reticulum of dairy cows using ingestion pattern and rumination behavior data gathered by automated data recording systems. The data of 13 ruminally fistulated lactating cows were collected at the experimental station of the Friedrich-Loeffler-Institut (Brunswick, Germany). The data included continuous pH measurements, which were recorded simultaneously in the reticulum by pH-measuring boluses and in the ventral rumen by a separate data logger. In addition, rumination behavior was measured using jaw movement sensors, and feed and water intakes were recorded by transponder-assisted systems. Milk yield and body weight were determined during and after each milking, respectively. For statistical evaluation, the data were analyzed using time-series modeling with multiple linear mixed regressions. Before applying the developed mathematical statistical modeling, we performed a plausibility assessment to ensure data quality. The major part of the mathematical statistical modeling consisted of data preparation, where all variables were transformed into a uniform 1-min resolution. Signal transformations were used to model individual feed and water intakes as well as rumination behavior events over time. Our results indicated that diurnal pH curves of both the reticulum and ventral rumen could be predicted by the transformed feed and water intake rates. Rumination events were associated with a marginal temporal increase in pH. We observed that the pH of the ventral rumen was delayed by approximately 37 min compared with that of the reticulum, which was therefore considered in the modeling. With the models developed in this study, 67.0% of the variance of the reticular pH curves and 37.8% of the variance of the ruminal pH curves could be explained by fixed effects. We deduced that the diurnal pH course is, to a large extent, associated with the animal's individual feed intake and rumination behavior.

Methodology for pH measurement in high alkali cementitious systems

A methodology for calibrating pH meters in highly alkaline solutions such as those relevant to cementitious systems is presented. This methodology uses an extended form of the Debye-Hückel equation to generate a calibration curve of pH vs. the measured electrochemical potential (mV) based on a series of aqueous alkali hydroxide solutions of known concentrations. This methodology is compared with the ‘built-in’ process of calibration based upon pH 4, 7, and 10 standard solutions. The built-in calibration process underestimates the real pH values by up to 0.3 log units, which is attributed to the alkali error. A spreadsheet for determining the calibration curve and its application to pH meter readings is provided as Supporting Information. The implications of improperly calibrated pH meters on interpreting solution chemistry in cementitious systems are discussed.

4081 Quantifying pH buffering capacity and kinetics of tumor and healthy tissue to understand and exploit differences in biology

OBJECTIVES/GOALS: The purpose of this work is to investigate natural buffering capacity of liver tissue and tumors, to understand and exploit differences for therapy. Using this work, we will determine the concentrations of reagents (acids or bases) used in ablation treatment to optimize treatment by increasing tumor toxicity and minimizing healthy tissue toxicity. METHODS/STUDY POPULATION: For this preliminary study, two methods will be used: benchtop pH experiments ex vivo and non-invasive imaging using acidoCEST MRI in vivo. For ex vivo, two types of tissues will be tested: non-cancerous liver and tumor tissue from HepG2 inoculated mice (n = 10). After mice are euthanized, pH will be measured in tissue homogenates at baseline and then the homogenates will be placed in either acidic (acetic acid) or basic (sodium hydroxide) solutions with varied concentrations (0.5–10M) and time recorded until pH returns to baseline. For in vivo imaging, Mia PaCA-2 flank model mice (n = 10) will be imaged with acidoCEST MRI to quantify pH at baseline. Mice will then be injected intratumorally with (up to 100 μL of) acid or base at increasing concentrations and imaged to quantify pH changes in the tumor. RESULTS/ANTICIPATED RESULTS: For this study, buffering capacity is defined as the concentration threshold for which tissue can buffer pH back to within normal range. Non-cancerous tissue is likely to buffer a wider range of concentrations compared to tumor tissue. From the benchtop experiment, comparison of time-to-buffer will be made for each concentration of acid/base for the two tissue types. AcidoCEST MRI will provide in vivo buffering capacity and potentially demonstrate tumor heterogeneity of buffering capacity. For both experiments, a pH vs. concentration curve for the two tissue types will allow for comparison of ex vivo to in vivo experiments, which will differentiate contributions of local tissue buffering capacity from the full body’s natural bicarbonate buffer system that depends on respiration and blood flow. DISCUSSION/SIGNIFICANCE OF IMPACT: The pH of the body must be maintained within a narrow range. With cancer, impairment in regulation of tumor metabolism causes acidosis, lowering extracellular pH in tumors. It remains unclear if pH plays a role in local recurrence or tumor toxicity. This work will determine if acidoCEST MRI can measure deliberate alteration of pH and how this change affects biology.

Spline surfaces with C1 quintic PH isoparametric curves

Given two spatial C1 PH spline curves, aim of this paper is to study the construction of a tensor–product spline surface which has the two curves as assigned boundaries and which in addition incorporates a single family of isoparametric PH spline curves. Such a construction is carried over in two steps. In the first step a bi–patch is determined in a ‘Coons–like’ way having as boundaries two quintic PH curves forming a single section of given spline curves, and two polynomial quartic curves. In the second step the bi–patches are put together to form a globally C1 continuous surface. In order to determine the final shape of the resulting surface, some free parameters are set by minimizing suitable shape functionals. The method can be extended to general boundary curves by preliminary approximating them with quintic PH splines.

Impact of surface complexation and electrostatic interactions on pH front propagation in silica porous media

The coupled effects of pH and ionic strength impact a variety of geochemical processes in the subsurface. In this study, we investigate the interactions of H+ and major ions at the surface-solution interface of silica porous media under advection-dominated flow-through conditions. A series of 21 column experiments were performed by systematically injecting solutions of different pH and ionic strengths. Three types of porous media (i.e., two natural sands and quartz beads) were considered in order to explore differences in surface/solution interactions among quartz materials. Multiple lines of evidence were used to characterize the geochemical processes taking place during the flow-through experiments: (i) breakthrough curves of pH and major ions were measured at the column outlets; (ii) the natural sand surfaces were characterized by chemical extractions and scanning electron microscopy and the quartz structure was analyzed by XRD; (iii) reactive transport modeling was performed to quantitatively interpret the experimental results.We observed strong reactivity of the quartz surface characterized by significant release of protons when interacting with the major ions. The results also show significant differences in the quantity of protons emitted from the surfaces of the three silica porous media, as well as in the shape of the pH breakthrough curves. Reactive transport modeling was based on a multicomponent ionic transport formulation and on surface complexation description of the solid/solution interactions. The surface complexation model included the individual contributions of quartz and Fe/Al oxides present in the sand coatings with the component additive approach. For each medium, a single set of surface complexation parameters capable of reproducing the experimental dataset (i.e., 7 columns) was calibrated by parallelizing the simulations of the flow-through experiments. This approach allowed us to capture the pH and ionic species behavior within a large range of ionic strengths (i.e., [0–100] mM). The SCMs quantitatively show that H+ is released from quartz upon adsorption of Na+ and that the protonation of the oxides surfaces retards the pH front. Differences in acidity behavior between the silica surfaces seem to be primarily controlled by differences in surface topology, crystal structure of quartz and/or various presence of aluminosilicates. This study demonstrates that the reactivity and diversity of quartz surfaces in silica porous media and the complex interplay with oxide surfaces in the coatings control the transport of aqueous charged species in flow-through systems.

Characterization and extensive study of cubic and quintic algebraic trigonometric planar PH curves

This paper deals with Pythagorean hodograph curves of the spaces of algebraic trigonometric functions and trigonometric polynomials, $\text {span}\left \{1,t,\left \{{\cos \limits } \left ({kt}\right ), {\sin \limits } \left ({kt}\right )\right \}_{k=1}^{m}\right \} $ and $ \text {span}\left \{1,\left \{{\cos \limits } \left ({kt}\right ), {\sin \limits } \left ({kt}\right )\right \}_{k=1}^{m}\right \}, $ respectively. First, we propose a general characterization of planar PH curves in these spaces. Next, we consider the particular cases m = 1 and m = 2. For each of them, we give the general form of the control polygon of the PH curves, the implicit relations defining these curves, and their geometrical interpretations. Some examples and particular cases complete this study.

Removal of Lead(II) Ions from Industrial Waste Water using Biomaterials of Terminalia ivorensis Plant and its Composite with Fe-Alginate Beads as Adsorbents

Three effective adsorbents are developed for the removal of lead ions from industrial effluents based on stem powder of Terminalia ivorensis (TISP), its active carbon (TIAC) and a composite of Fe-alginatebeads doped with the active carbon (TIAC-beads). The beads are synthesized by crosslinking the Na-alginate with Fe3+ instead of conventional Ca2+, with an aim to improve its adsorptivity. The conditions for obtaining the uniform beads with good morphology are established. These sorbents are investigated for their adsoptivity for Pb2+ ions with respect to various extractions conditions and are optimized for the maximum removal of Pb2+. The sorption capacities are found to be: 34.0 mg/g for TISP, 39.0 mg/g for TIAC and 49.0 mg/g for TIAC-beads. The higher sorption of TIAC-beads may be due to the cumulative sorption nature of active carbon assisted by iron-alginate beads towards Pb2+. The optimum conditions are: for TISP: pH: 5, sorbent dosage: 2.0g/and, eqi. time: 120 min; for TIAC: pH: 7, sorbent dosage: 1.5 g/L; eqi. time: 90 min; and for TIAC-beads: pH: 6, sorbent dosage: 1.0 g/L and eqi. time: 60 min. Substantial removal of Pb2+ is noted in a range of pHs: 4 to 9 for TIAC-beads; 4 to 8 for TISP and 6 to 8 for TIAC. This permits the applicability of the sorbents in neutral as well as less acidic and basic solutions and it is a good feature as Pb2+ containing industrial effluents are inconsistent in their pHs. Three fold excess of co-ions marginally interfered. Thermodynamic studies reveal that the adsorption is endothermic and spontaneous. The high ΔH values, > 30.0 KJ/mol, emphasizes the chemical nature of binding between Pb2+ and surface functional groups of sorbent and is increasing in the order: TISP (32.385 KJ/mol) < TIAC (35.531 KJ/mol) < TIAC-beads (42.480 KJ/mol). This is supported by symmetrical humps with in the curves of pH vs. % removal. Positive ΔS values reflect disorder at the solid-liquid interface-an ideal condition for Pb2+ ions to cross the surface barrier existing at the solid/liquid interface, resulting in good adsorptivity. Negative ΔG values indicate the spontaneity of the sorption process. Spent TISP/TIAC/TIAC-beads can be regenerated and reused for 2 cycles for TISP, 3 cycles for TIAC and 3 cycles for TIAC-beads. The sorbents are successfully applied to remove Pb2+ form industrial effluents.

Construction of quartic PH curves via interpolating given points

Construction of quartic PH curves via interpolating given points

Computational model of electrode-induced microenvironmental effects on pH measurements near a cell membrane.

The mechanism of gas transport across cell membranes remains a topic of considerable interest, particularly regarding the extent to which lipids vs. specific membrane proteins provide conduction pathways. Studies of transmembrane (CO2) transport often rely on data collected under controlled conditions, using pH-sensitive microelectrodes at the extracellular surface to record changes due to extracellular CO2 diffusion and reactions. Although recent detailed computational models can predict a qualitatively correct behavior, a mismatch between the dynamical ranges of the predicted and observed pH curves raises the question whether the discrepancy may be due to a bias introduced by the pH electrode itself. More specifically, it is reasonable to ask whether bringing the electrode tip near or in contact with the membrane creates a local microenvironment between the electrode tip and the membrane, so that the measured data refer to the microenvironment rather than to the free surface. Here, we introduce a detailed computational model, designed to address this question. We find that, as long as a zone of free diffusion exists between the tip and the membrane, the microenvironment behaves effectively as the free membrane. However, according to our model, when the tip contacts the membrane, partial quenching of extracellular diffusion by the electrode rim leads to a significant increase in the pH dynamics under the electrode, matching values measured in physiological experiments. The computational schemes for the model predictions are based on semi-discretization by a finite-element method, and an implicit-explicit time integration scheme to capture the different time scales of the system.

Research on Well Trajectory Deduction Method Based on Pythagorean-Hodograph Quintic Space Curves

Considering the influence of key parameters such as bore angle, azimuth and sounding of wellbore, based on the spatial five-time PH curve with continuous unit tangent and directional curvature, no need for iteration, using Bessel polynomial interpolation method, optimization the spatial model and the curve description can accurately deduct the spatial parameters of the fifth point according to the determined four points of the space, and then establish the wellbore trajectory analytical equation to generate the well trajectory curve. Taking a directional well as an example, the wellbore trajectories of the wells from 403.9 meters to 976 meters were fitted by PH, cubic spline and linear interpolation method respectively, and compared with the real measuring points. The results show that the wells fitted by PH method, the differences of the bevel angle and the measured point, the azimuth angle and the measured point are 0.910° and 5.7°. The differences of the cubic spline and the measured point, the straight line method and the measured point are 4.240°, 5.86° and 6.54°, 9.09°. For the PH method, the trajectory inclination and azimuth differences are the smallest, which are 3.51% and 3.17%.

Antimicrobial films of poly(2-aminoethyl methacrylate) and its copolymers doped with TiO2 and CaCO3

Polymeric coatings with positive surface charge offer potential antimicrobial activity, which they owe to a simple electrostatic attraction with negatively charged bacterial walls and membranes. We describe synthesis and characterization of poly(2-aminoethyl methacrylate) and its copolymers with methyl methacrylate and butyl acrylate, as potential binders for antimicrobial solvent-cast paints. TiO2 and CaCO3 mineral particles were employed as model pigments/fillers, as they are used in most real-life paint formulations. Electrokinetic (ζ) potential and antimicrobial activity of thin films made of the (co)polymers in the absence and presence of TiO2 and CaCO3 nanopowders were assessed using streaming current measurements and microbial growth inhibition tests, respectively. Independently of the structure of the monomers used for the synthesis, the films showed positive ζ-potential values (up to +95 mV) in the pH range 3.5-8.0. The presence of mineral particles at 50% dry weight of the films did not affect significantly the ζ(pH) curves. The films made of the mixed dispersions remained positively charged and inhibited growth of both Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria, as well as yeast (C. albicans). The mixed polymeric-mineral films described in this study seem to be promising potential candidates for designing antimicrobial coatings aimed to prevent spreading of bacterial infections.