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The aim of this paper is to present a method for predicting the effect of temperature on contact angles and wetting transitions for n-alkanes on PTFE. The analysis is based on the ...effect of temperature on two closely related phenomena, which are critical in the determination of contact angles: intermolecular forces and the thickness of an adsorbed film in the region adjacent to the three-phase contact.
Considering solely van der Waals forces, it is possible to reproduce the experimental temperature dependence of contact angles. At low temperature values, contact angles show a small and linear decrease with temperature. For higher temperature values, substantially larger decreases are exhibited by the more volatile alkanes. In the case of n-octane, a single transition from partial to total wetting is found at 443K. This transition, which arises from the vanishing of the effective Hamaker constant at 430K, is characterized by a surface specific heat exponent close to one, indicating the existence of a first order wetting transition. For the less volatile alkanes, the contact angle decrease is progressively less pronounced as the volatility decreases in such a way that for n-hexadecane the contact angle remains approximately constant throughout the temperature range under study.
The purpose of this work is to study a generalisation of Dung’s abstract argumentation frameworks that allows representing
recursive attacks
, that is, a class of attacks whose targets are other ...attacks. We do this by developing a theory of argumentation where the classic role of
attacks
in defeating arguments is replaced by a subset of them, which is “extension-dependent” and which, intuitively, represents a set of “valid attacks” with respect to the extension. The studied theory displays a conservative generalisation of Dung’s semantics (complete, preferred, stable and grounded) and also of its principles (conflict-freeness, acceptability and admissibility). Furthermore, despite its conceptual differences, we are also able to show that our theory agrees with the AFRA interpretation of recursive attacks for the complete, preferred, stable and grounded semantics and with a recent flattening method.
Rationale
Clozapine has proven to be superior to other antipsychotic drugs in the treatment of schizophrenia but is under-prescribed due to its potentially severe side effects. Clozapine-induced ...sialorrhea (CIS) is a frequent and extremely uncomfortable side effect, which remains understudied.
Objectives
To examine the prevalence of diurnal and nocturnal CIS in a sample of patients treated with clozapine, and to evaluate its impact on quality of life.
Methods
We conducted a cross-sectional, observational study of 130 patients with schizophrenia spectrum disorders treated with clozapine. The prevalence of CIS was evaluated via specific sialorrhea scales. None of the patients included in the study was receiving a specific treatment for hypersalivation during the study period. Possible associations between sialorrhea and clinical and quality of life variables were analyzed.
Results
Of 130 subjects, 120 (92.3%) suffered from CIS. Eighty-one (62.31%) suffered from diurnal CIS, 115 (88.56%) from nocturnal CIS, and 85 (65.38%) suffered from both. Significant positive associations between quality of life and diurnal CIS (
B
= 0.417;
p
= 2.1e − 6,
R
2
= 0.156) and nocturnal CIS (
B
= 0.411;
p
= 7.7e − 6,
R
2
= 0.139) were detected. Thirty per cent of the subjects reported a moderate to severe negative impact of sialorrhea on their quality of life.
Conclusions
The present study suggests that CIS is highly prevalent in patients with schizophrenia and has an important impact on quality of life in one-third of our sample. Therefore, the inclusion of a systematic evaluation and treatment of CIS in standard clinical practice is highly recommended.
Trial registration
Clinical Trials (
https://clinicaltrials.gov
) under reference NCT04197037.
The coupling of membrane separation and photocatalytic oxidation has been studied for the removal of pharmaceutical pollutants. The retention properties of two different membranes (nanofiltration and ...reverse osmosis) were assessed. Comparable selectivity on the separation of pharmaceuticals were observed for both membranes, obtaining a permeate stream with concentrations of each pharmaceutical below 0.5 mg L−1 and a rejected flux highly concentrated (in the range of 16–25 mg L−1 and 18–32 mg L−1 of each pharmaceutical for NF-90 and BW-30 membranes, respectively), when an initial stream of six pharmaceuticals was feeding to the membrane system (10 mg L−1 of each pharmaceutical). The abatement of concentrated pharmaceuticals of the rejected stream was evaluated by means of heterogeneous photocatalytic oxidation using TiO2 and Fe2O3/SBA-15 in presence of hydrogen peroxide as photo-Fenton system. Both photocatalytic treatments showed remarkable removals of pharmaceutical compounds, achieving values between 80 and 100%. The nicotine was the most refractory pollutant of all the studied pharmaceuticals. Photo-Fenton treatment seems to be more effective than TiO2 photocatalysis, as high mineralization degree and increased nicotine removal were attested. This work can be considered an interesting approach of coupling membrane separation and heterogeneous photocatalytic technologies for the successful abatement of pharmaceutical compounds in effluents of wastewater treatment plants.
•Coupling of membrane separation and photocatalytic oxidation systems.•Permeate stream free of pharmaceuticals and rejected flux treated by photo-oxidation systems.•A feasible alternative for the treatment of pharmaceutical contaminated wastewaters.•The heterogeneous photocatalysts, prevents the contamination of the effluents by metallic ions.
The compact geometry and outstanding mechanical properties of ceramic monoliths are valuable features when designing reusable standard affinity chromatography columns. High throughput protein ...separations are becoming standard industrial practice. Column reuse is an important consideration for the development of separation processes when production rate per unit volume of column is taken into account. Due to the cost and downtime needed to regenerate chromatographic columns, throughput depends on the use of the same column for several adsorption–desorption cycles without a significant loss in adsorption. An adsorption–desorption dynamic model was developed and used to estimate the optimum reuse of ceramic monolith columns in affinity chromatography. The model experimental metal chelate affinity chromatography (IMAC) system is a ceramic monolith covered with agarose type D-5 activated with 1.4 butanediol diglycidyl ether as spacer arm, iminodiacetic acid as chelating agent, and Cu2+ as ligand. The effect of performing several adsorption/elution cycles on column performance was evaluated using five monoliths at different flow rates, for a total of five cycles each. The strategy used to interpret experimental results leads to a theoretical model for successive monolith reuses that can be readily used to determine the optimal reuse of monoliths on the basis of maximum production rate per volume of chromatographic columns.
Affinity between biomolecules and surface active materials induces the formation of a Langmuir-biofilm (L-biofilm), as the basis for the development of high resolution bioseparation processes. ...Experiments were performed to characterize the interaction between amphiphilic molecules and proteins, establishing the optimal conditions for bioseparation. In the model L-biofilm system, Bovine Serum Albumin (BSA) was the protein and arachidic acid was the amphiphilic molecule. The L-biofilm formation is promoted by interactions within the subphase (polar groups) and at the interface (non polar groups). The first stage of the process to create the L-biofilm is the migration of BSA from the water subphase towards the air–water interface. This step is followed by a two-step process that includes diffusion and rearrangement. This process has been modeled using a double exponential equation and it is dominated by diffusion, although rearrangement reveals as a faster process. Once the L-biofilm is formed, phase behavior isotherms first show compressible films with areas per molecule larger than the corresponding to pure arachidic acid, due to the penetration of BSA molecules into the acid monolayer. As compression progresses, BSA is squeezed out of the interface although remains attached to the acid in the subphase. The L-biofilm shows hysteresis, in contrast to the behavior of a pure acid L-film. A probable cause for this behavior is the folding of BSA in the L-biofilm upon compression and a slower unfolding during expansion with loss of surface active material in successive cycles of compression–expansion. Regarding the L-biofilm stability, experimental data show a phase of significant film reorganization, due to the presence of BSA, followed by migration of the L-biofilm towards the subphase. A key variable was subphase pH, because it induces changes in the conformational structure of BSA. Changes in structure affect diffusion, rearrangement and solubility and, therefore, L-biofilm formation, structure and composition. Brewster Angle Microscopy studies show the compactness of the L-biofilms, confirming a good level of L-biofilm formation at pH=3.8 and 5.1 and a rather low formation at pH=8.2.
► A study of the L-biofilms formed by BSA and arachidic acid has been carried out. ► These L-biofilms are compressible, stable and compact. ► The lower the pH, the greater the adsorption of BSA at the interface. ► The lower the pH, the greater the incorporation of BSA to the L-biofilm. ► These L-biofilms suffer hysteresis if compression–expansion cycles are performed.
•Langmuir–Blodgett can be used as a high resolution bioseparation technique.•Bovine serum albumin (BSA) is separated using arachidic acid (AA) as ligand.•Multilayers of BSA-AA are deposited on glass ...substrates with the aim of cadmium.•After 6 strokes, 48% of the protein initially present at the subphase is removed.•BSA stands vertically in the biofilm increasing roughness compared to pure AA films.
Affinity separation by Langmuir–Blodgett (LB) deposition is a high resolution bioseparation procedure that takes advantage of the affinity between biomolecules and surface active materials, inducing the formation of a Langmuir-biofilm (L-biofilm) which is later removed from the air–water interface by deposition onto a solid substrate. This novel method is here applied to the separation of bovine serum albumin (BSA) by using arachidic acid (AA) as a ligand. Optimization of the experimental procedure choosing those conditions which favor Y-type multilayer deposition and low protein solubility is key. Both goals are achieved simultaneously by using Cd2+ as a counterion and a pH equal to the counterion pKA, that is pH=5.6. The selection of a target area of 22Å2/molecule, a value close to the footprint of AA in solid state, ensures that the protein will be squeezed out of the interface and bounded to the ligand. The transfer ratio (TR) values obtained during depositions for up to 6 layers show that the deposition was successful, and spectrophotometric analysis show that a 48% of the protein initially present at the subphase is removed. Additionally, the efficiency of separation for each layer is close to 100% with respect to the maximum amount of BSA that could fit in the film, assuming that the molecule stands vertically in the L-biofilm structure (long axis perpendicular to the solid). Atomic Force Microscopy (AFM) analysis qualitatively confirms the presence of the BSA in the deposited biofilm. The images illustrate that the presence of BSA strongly affects the topography of the surface, in the form of roughness and protrusions, unlike a pure arachidic acid monolayer. Roughness clearly increases when BSA is present in the deposited film. In summary, experimental evidence indicates the high potential of LB as a method for purification of proteins.
The objective of this paper is to point out the close relationship between contact line dynamics and LB film depositions, and it is designed to serve as a blueprint for future analysis of the LB ...technique. Moving contact lines and contact angles play a major role in Langmuir–Blodgett ultrathin film depositions. Although the effect of contact angles has been recognized for many years, a fundamental and comprehensive explanation of the phenomena taking place at the contact line has not been formulated before. Our understanding of contact line dynamics has improved thanks to careful experiments and new theoretical developments. Flow patterns depend on dynamic contact angle and the ratio of viscosities of the gas and liquid phases. More recently dynamic contact angles—and flow patterns—have been linked to forces of molecular and double-layer origin. The dynamic relationship of flow patterns to interfacial and transport properties can be used to explain seemingly contradictory experimental results reported by researchers during more than 60 years of experience with the L–B technique. Windows of operability can be defined for X-type and Z-type depositions that are useful in the design of experimental and industrial L–B deposition equipment.
