Assessment of treatability of the Tietê River through a process of coagulation-flocculation associated with hydrodynamic cavitation and ozonation.

As it flows through the city of São Paulo, the Tietê River receives heavy discharges of industrial effluents and domestic sewage, resulting from the city's continuous urban expansion and the inadequacy of its sanitary sewage system. This study focused on an analysis of the efficiency of PGα21Ca and quaternary ammonium tannate, water purification products, based on coagulation-flocculation and sedimentation tests, followed by treatment with a hydrodynamic cavitation reactor associated with ozonation in the treatment of Tietê River water. The removal of turbidity, apparent color, and chemical oxygen demand (COD) were evaluated. Jar testing assays were conducted, and the best turbidity removal rates were obtained with a concentration of 300 mg L-1 for PGα21Ca and 150 mg L-1 for quaternary ammonium tannate. The coagulation-flocculation treatment removed approximately 93% of turbidity for both coagulants. After combining coagulation-flocculation with hydrodynamic cavitation with ozonation, the final COD removal rate applying PGα21Ca was 47.63% in 1 hour of reaction, while that of quaternary ammonium tannate was 40.13% in 2 hours of reaction. Although the results appear to indicate the superior performance of PGα21Ca, it should be noted that the treatment with quaternary ammonium tannate also provided good results in reducing turbidity, COD, and apparent color, using a smaller dose of this coagulant and that its use may be more advantageous from an environmental point of view, due to its natural composition.

Effect of incorporating modified pinhão starch in alginate-based hydrogel beads for encapsulation of bioactive compounds by hydrodynamic electrospray ionization jetting.

Known for its antioxidant properties, Araucaria angustifolia bracts extract was encapsulated using hydrodynamic electrospray ionization jetting within calcium alginate cross-linked hydrogel beads with varying contents of modified pinhão starch. The rheological properties of the dispersions and analysis of the physicochemical and digestive properties of encapsulated beads were studied. The results demonstrated that dispersions containing starch exhibited higher viscosity and reduced compliance values, indicating samples with stronger, more compact, and stable structures that are less susceptible to deformation. This was confirmed by the beads rupture strength test. The ATR-FTIR analysis suggest that no new chemical bonds were formed, with encapsulation being responsible only for physical interactions between the functional groups of the polymers used and the active groups of the compounds present in the extract. The thermal stability of starch-containing beads was higher. Total tannins were higher in beads containing starch, with 53.61 %, 56.83 %, and 66.99 % encapsulation yield for samples with 2 %, 4 %, and 6 % starch, respectively, and the remaining antioxidant activity ranged from 96.04 % to 81.08 %. In vitro gastrointestinal digestion simulation indicated that the highest releases occurred in the intestinal phase, ranging from 60.72 % to 63.50 % for the release of total phenolic compounds.

Sterilization of Human Amniotic Membrane Using an Ozone Hydrodynamic System.

Human amniotic membrane (hAM) is an important biomaterial for Tissue Engineering, due to its great regenerative properties and potential use as a scaffold. The most used procedure to sterilize biomaterials is gamma-irradiation, but this method can affect several properties, causing damage to the structure and reducing the growth factors. The present work evaluated the efficiency of a new method based on ozonated dynamic water for hAM sterilization. HAM fragments were experimentally contaminated with Staphylococcus aureus, Escherichia coli, Candida albicans, Staphylococcus epidermidis, and Clostridium sporogenes (106 CFU/mL) and submitted to sterilization process for 5, 10 and 15 min. The analyses did not reveal microbial activity after 10 min for S. aureus and C. sporogenes and after 15 min for E. coli and S. epidermidis. The microbial activity of C. albicans was reduced with the exposure time increase, but the evaluated time was insufficient for complete sterilization. The depyrogenation process was investigated for different ozonation times (15, 20, 25, 30, and 35 min) to evaluate the ozone sterilization potential and presented promising results after 35 min. The ozone effect on hAM structure was evaluated by histological analysis. A decrease in epithelium average thickness was observed with the exposure time increase. Furthermore, some damage in the epithelium was observed when hAM was exposed for 10 and 15 min. It can indicate that ozone, besides being effective in sterilization, could promote the hAM sample's de-epithelization, becoming a possible new method for removing the epithelial layer to use hAM as a scaffold.

Hydrodynamic cavitation-assisted acid pretreatment and fed-batch simultaneous saccharification and co-fermentation for ethanol production from sugarcane bagasse using immobilized cells of Scheffersomyces parashehatae.

A new alternative for hydrodynamic cavitation-assisted pretreatment of sugarcane bagasse was proposed, along with a simultaneous saccharification and co-fermentation (SSCF) process performed in interconnected columns. Influential variables in the pretreatment were evaluated using a statistical design, indicating that an ozone flow rate of 10 mg min-1 and a pH of 5.10 resulted in 86 % and 72 % glucan and xylan hydrolysis yields, respectively, in the subsequent enzymatic hydrolysis process. Under these optimized conditions, iron sulfate (15 mg L-1) was added to assess Fenton pretreatment, resulting in glucan and xylan hydrolysis yields of 92 % and 71 %, respectively, in a material pretreated for 10 min. In SSCF, ethanol volumetric productivities of 0.33 g L-1 h-1 and of 0.54 g L-1 h-1 were obtained in batch and fed-batch operation modes, achieving 26 g L-1 of ethanol in 48 h in the latter mode.

Swirling Fluid Reduces the Bounce of Partially Filled Containers.

Certain spatial distributions of water inside partially filled containers can significantly reduce the bounce of the container. In experiments with containers filled to a volume fraction ϕ, we show that rotation offers control and high efficiency in setting such distributions and, consequently, in altering bounce markedly. High-speed imaging evidences the physics of the phenomenon and reveals a rich sequence of fluid-dynamics processes, which we translate into a model that captures our overall experimental findings.

Numerical simulation of flow-diverting stent: comparison between branches in bifurcation brain aneurysm.

The usage of flow-diverting stents in the treatment of intracranial aneurysms is widespread due to their high success and low complication rates. However, their use is still not officially recommended for bifurcation aneurysms, as there is a risk of generating ischemic complications due to the reduced blood flow to the jailed branch. Many works utilize computational fluid dynamics (CFD) to study how hemodynamic variables respond to flow diverter placement, but few seem to use it to verify flow variation between branches of bifurcation aneurysms and to aid in the choice of the best ramification for device placement. This investigation was performed in the present work, by comparing wall shear stress (WSS) and flowrates for a patient-specific scenario of a middle cerebral artery (MCA) aneurysm, considering device placement on each branch. A secondary objective was to follow a methodology that provides fast results, envisioning application to daily medical practice. The device was simplified as a homogeneous porous medium, and extreme porosity values were simulated for comparison. Results suggest that stent placement on either branch is both safe and effective, significantly reducing WSS and flow into the aneurysm while maintaining flow to the different ramifications within acceptable thresholds.

Study of a light hydrocarbon fraction spill migration that occurred in an area of the Mexican southeast using computational fluid dynamics.

The present work aimed to study, predict and understand benzene migration that occurred during an industrial spill using numerical simulation by computational fluid dynamics. Advection, diffusion and adsorption were the main mechanisms considered that governed the spill incident. The incident occurred due to a fracture under a fuel oil storage tank. The tank was located on a hill 18 m high, and the initial value of benzene concentration (soil saturation) was 60 ppm. When the spill was discovered, samples in the affected zone were taken using an experimental design. Many samples showed a greater concentration of benzene than allowed by Mexican Official Standards (MOSs) (15 ppm). The concentrations found 100 m away from the spill were around 60 to 15 ppm. Due to the spill being under the tank, it was difficult to discover. The numerical simulation provided an estimate that the spill started around 2 years ago. The type of soil in the afflicted zone is rocky, and, consequently, it is difficult to estimate how long it will take to reach the concentration allowed by the MOSs, but the numerical simulation predicts that this concentration will be reached in 14 years. Experimental values of the spill contaminant concentration were statistically similar to the CFD estimated data (p < 0.05).

Simultaneous hydrodynamic cavitation and glow plasma discharge for the degradation of metronidazole in drinking water.

In this study, a novel hydrodynamic cavitation unit combined with a glow plasma discharge system (HC-GPD) was proposed for the degradation of pharmaceutical compounds in drinking water. Metronidazole (MNZ), a commonly used broad-spectrum antibiotic, was selected to demonstrate the potential of the proposed system. Cavitation bubbles generated by hydrodynamic cavitation (HC) can provide a pathway for charge conduction during glow plasma discharge (GPD). The synergistic effect between HC and GPD promotes the production of hydroxyl radicals, emission of UV light, and shock waves for MNZ degradation. Sonochemical dosimetry provided information on the enhanced formation of hydroxyl radicals during glow plasma discharge compared to hydrodynamic cavitation alone. Experimental results showed a MNZ degradation of 14% in 15 min for the HC alone (solution initially containing 300 × 10-6 mol L-1 MNZ). In experiments with the HC-GPD system, MNZ degradation of 90% in 15 min was detected. No significant differences were observed in MNZ degradation in acidic and alkaline solutions. MNZ degradation was also studied in the presence of inorganic anions. Experimental results showed that the system is suitable for the treatment of solutions with conductivity up to 1500 × 10-6 S cm-1. The results of sonochemical dosimetry showed the formation of oxidant species of 0.15 × 10-3 mol H2O2 L-1 in the HC system after 15 min. For the HC-GPD system, the concentration of oxidant species after 15 min reached 13 × 10-3 molH2O2L-1. Based on these results, the potential of combining HC and GPD systems for water treatment was demonstrated. The present work provided useful information on the synergistic effect between hydrodynamic cavitation and glow plasma discharge and their application for the degradation of antibiotics in drinking water.

Hydroinformatic tools and their potential in the search for missing persons in rivers.

This research proposes a methodological approach to search floating bodies or floating body parts in rivers using hydroinformatic tools. These tools may allow possible search locations and potential release sites to be determined. The approach draws from hydrometric field information, two-dimensional (2D) hydrodynamic modeling, particle tracking (PT) models, and large-scale particle image velocimetry (LSPIV). This methodology was applied to a case study of the La Miel river in Colombia, where existing reports of deceased persons are available. A series of hydraulic accidents have been defined to represent the hydrodynamic and transport processes that occur in such situations. The results indicate that potential search locations, namely places where human floating bodies or floating body parts may be found, are principally on the left and right shores of recirculation systems.

A detailed analysis in thoracic aorta by means of the entropy generation rate: Prediction of the atherosclerotic lesion.

A detailed numerical analysis is carried out in a real human thoracic aorta by means of the Computational Fluid Dynamics (CFD) for the prediction of the atherosclerosis lesion. Common hemodynamics parameters, such as, the oscillatory shear index (OSI) and the time average wall shear stress (TAWSS) are used for the prediction of the atherosclerosis lesion. Furthermore, the entropy generation rate is considered to obtain the main irreversibilities that occurs inside the thoracic aorta for the prediction of the atherosclerosis lesion. The model considers the blood flow inside the thoracic aorta in an unsteady state. The results show contours of velocity, streams lines, velocity profiles and the comparison of the hemodynamics parameters OSI versus TAWSS. Moreover, contours of the entropy generation rate are showed inside the aorta. The time averaged entropy generation rate (TAEGR) is obtained as a result of the entropy generation analysis. Finally, TAEGR index is compared and discussed with the common hemodynamics parameters, OSI and TAWSS. The accuracy to detect prone locations to atherosclerotic development in the real aorta using the TAEGR in comparison to the OSI and the TAWSS is in good agreement.

Intensification of Red-G dye degradation used in the dyeing of alpaca wool by advanced oxidation processes assisted by hydrodynamic cavitation.

Red-G dye is one of the main dyes used in the textile industry to dye alpaca wool. Therefore, considering the large volume of processed wool in Perú, the development of efficient technologies for its removal is a present scientific issue. In this study, an integrated system based on hydrodynamic cavitation (HC) and photo-Fenton process was evaluated to remove the Red-G dye. Using a hybrid cavitation device (venturi + orifice plate), the effect of pH was evaluated, achieving 21 % of removal at pH 2 which was more than 80 % higher compared to pH 4 and 6. The effect of temperature was also evaluated in HC-system at pH 2, where percentage of dye degradation increased at lower temperatures (around 20 °C). Then, 50.7 % of dye was removed under optimized condition of HC-assisted Fenton process (FeSO4:H2O2 of 1:30), that value was improved strongly by UV-light incorporation in the HC-system, increasing to 99 % removal efficiency with respect to HC-assisted Fenton process and reducing the time to 15 min. Finally, the developed cavitation device in combination with photo-Fenton process removed efficiently the dye and thus could be considered an interesting option for application to real wastewater.

Micellar entanglement and its relation to the elastic behavior of wormlike micelle fluids.

HYPOTHESIS: The elastic contribution to the fluid dynamics of wormlike micellar solutions makes these fluids unique due to the distinctive self-assembled micellar network formed by tubular micelles. Measured mesoscopic scales of the micellar network related to the degree of entanglement can give guidelines for understanding the origin of elastic forces and their effect on rheological response. EXPERIMENTS: Different experiments were made as flow curves, rotating the internal or external cylinder in a Couette geometry, small and large oscillatory shear tests, and linear shear banding observations, all of them to determine how elastic forces modify the rheological behavior in systems made of different ratios of hexadecyltrimethylammonium bromide (CTAB)/sodium salicylate (NaSal) and different ratios of CTAB/NaNO3. Diffusive wave spectroscopy micro-rheology was also performed to measure the mean square displacements of microspheres embedded in the micellar fluids to obtain their high-frequency viscoelastic spectra. With this information, the entanglement index κ, the ratio of the total contour of the micelles to the entanglement length, was estimated and correlated with the rheological behavior. FINDINGS: The entanglement index is a valuable piece of information to understand the origin of the contribution of the elastic forces from a molecular point of view on the fluid dynamics of wormlike micelle solutions.

Morphological pattern of the dermal denticles of the Southern sawtail catshark Galeus mincaronei Soto, 2001.

Dermal denticles cover the skin of sharks for protection and may have additional functions, depending on the environment. The aim of the present study was to analyze the morphological pattern of dermal denticles across the body of the poorly known deep-water catshark Galeus mincaronei, which is endemic to Southern Brazil. Additionally, we aimed to identify differences between sexes and stages of sexual maturity. For this purpose, we analyzed patches of eight skin samples from body regions, that is, the head, body, and tail. Dermal denticles were imaged using scanning electron microscopy. Measurements of crown morphological variations (length and width) and density of dermal denticles were performed. Nine characters of dermal denticle morphology were selected to describe a morphological pattern using principal component analysis (PCA). The first PCA axis explained 45.2% of the variation, the second explained 33%, and the third explained 14.3%, together explaining 92.5% of the total variation in denticle morphology. We identified three groups of dermal denticle crown morphologies and their possible functions. The first was composed of nostril and snout denticles, which might suggest abrasion strength functions; the second was composed of most body denticles, such as those in the cranium, on the left side of the body, and on the pectoral, dorsal, and caudal fins, which might be related to generalized functions; and the third was composed of only caudal crest denticles, which might indicate defense functions with hydrodynamic properties in G. mincaronei. Likewise, our results reveal variations in dermal denticle morphology and arrangement along the three maturity stages considered in both sexes. Similarly, sexual dimorphism in the crown width and morphology of dermal denticles was observed in developing and mature individuals. Our results are the first to reveal the morphological variation of dermal denticles in relation to function, sex, and ontogeny of individual G. mincaronei.

Capsule-Based dry powder inhaler evaluation using CFD-DEM simulations and next generation impactor data.

Capsule-based, single-dose dry powder inhalers (DPIs) are commonly-used devices to deliver medications to the lungs. This work evaluates the effect of the drug/excipient adhesive bonding and the DPI resistances on the aerosol performance using a combination of empirical multi-stage impactor data and a fully-coupled computational fluid dynamics (CFD) and discrete element method (DEM) model. Model-predicted quantities show that the primary modes of powder dispersion are a function of the device resistance. Lowering the device resistance increases its capacity to transport a wider range of particle size classes toward the outlet and generate more intense turbulence upstream therein. On the other hand, a higher device resistance increases the velocity of the tangential airflow along the device walls, which in turn increases the intensity of particle/device impaction. Correlating model data and experimental results shows that these differing powder dispersion mechanisms affect different formulations differently, with finer aerosols tending to result when pairing a lower resistance device with formulations that exhibit low API/excipient adhesion, or when pairing a high resistance device with more cohesive formulations.

Hydrodynamic cavitation through a bio-inspired fast-closing plunger mechanism: experiments and simulations.

Experimental and numerical results are reported for the internal and external flow fields evolving in a bio-inspired snapping plunger. The experimental evidence underlines the nature of the dynamic-coupling between the processes taking place inside and outside the device. Two main structures dictate the properties of the external flow field: a strong jet which is followed by a vortex ring. Internally, complex patterns of cavitating structures are simultaneously produced in the chamber and the venturi-like conduit. We find the cavitation cycle to be suitably described by the Rayleigh-Plesset model and, thus, proceed to characterize the coupling of both fields in terms of the fluctuations of the velocity. All main parameters, as well as the energy released to the fluid during the collapse, are found to be within the same order-of-magnitude of previously known experimental results for isolated bubbles of comparable size.

Computational Fluid Dynamics to Assess the Future Risk of Ascending Aortic Aneurysms. / Fluidodinâmica Computacional na Avaliação do Risco Futuro de Aneurismas de Aorta Ascendente.

BACKGROUND: A methodology to identify patients with ascending aortic aneurysm (AsAA) under high risk for aortic growth is not completely defined. OBJETIVE: This research seeks to numerically characterize the aortic blood flow by relating the resulting mechanical stress distribution with AsAA growth. METHODS: Analytical, observational, single-center study in which a computational fluid dynamics (CFD) protocol was applied to aortic computed tomography angiogram (CTA) images of patients with AsAA. Two CTA exams taken at a minimum interval of one year were obtained. From the CTA-gathered images, three-dimensional models were built, and clinical data were registered. Study of velocity field and coherent structures (vortices) was performed aiming to relate them to the presence or absence of aneurysm growth, as well as comparing them to the patients' clinical data. The Kolmogorov-Smirnov test was used to evaluate the normality of the distribution, and the non-parametric Wilcoxon signed-rank test, for non-normal distribution, was used to compare the paired data of the aortic angles. Statistical significance was set at 5%. RESULTS: The incident jet in the aortic wall generated recirculation areas in the posterior region of the jet, inducing complex vortices formation in the group with aneurysm growth, leading to an average pressure increase in the ascending aortic wall between exams. In the group without aneurysm growth, the average pressure decreased. CONCLUSION: This pilot study showed that CFD based on CTA may in the near future be a tool to help identify flow patterns associated with AsAA remodeling process.

FUNDAMENTOS: Uma metodologia para identificação de pacientes portadores de aneurisma de aorta ascendente (AAAs) sob alto risco de remodelamento aórtico não está completamente definida. OBJETIVO: Esta pesquisa objetiva caracterizar numericamente o fluxo sanguíneo aórtico, relacionando a distribuição do estresse mecânico resultante com o crescimento de AAAs. MÉTODOS: Estudo analítico, observacional, unicêntrico, em que um protocolo de fluidodinâmica computacional (CFD - Computacional Fluid Dynamics) foi aplicado a imagens de angiotomografia computadorizada (ATC) de aorta de pacientes portadores de AAAs. Duas ATC de aorta com pelo menos um ano de intervalo foram obtidas. Dados clínicos dos pacientes foram registrados e, a partir das imagens de ATC, foram gerados modelos tridimensionais. Foram realizados estudos do campo de velocidade e estruturas coerentes (vórtices) com o objetivo de relacioná-los ao crescimento ou não do aneurisma e, posteriormente, compará-los com os dados clínicos dos pacientes. O teste de Kolmogorov-Smirnov foi utilizado para avaliar a normalidade da amostra e o teste não-paramétrico Wilcoxon signed-rank foi aplicado para comparações de dados pareados entre os ângulos aórticos. A significância estatística foi fixada em 5%. RESULTADOS: Para o grupo que apresentou crescimento do aneurisma, a incidência do jato na parede aórtica gerou áreas de recirculação posterior ao jato, induzindo à formação de vórtices complexos, ocasionando um incremento na pressão média no endotélio aórtico. O grupo sem crescimento do aneurisma apresentou diminuição na pressão média. CONCLUSÃO: Este estudo piloto mostrou que a CFD baseada em ATC pode, em um futuro próximo, ser uma ferramenta auxiliar na identificação dos padrões de fluxo associados ao processo de remodelamento de AAAs.

Influence of design and material characteristics on 3D printed flow-cells for heat transfer-based analytical devices.

Redesigning 3D-printed flow cells is reported used for heat transfer based detection of biomolecules from a flow-through system to an addition-type measurement cell. The aim of this study is to assess the performance of this new measurement design and critically analyse the influence of material properties and 3D printing approach on thermal analysis. Particular attention is paid to reduce the time to stabilisation, the sample volume in order to make the technique suitable for clinical applications, and improving the sensitivity of the platform by decreasing the noise and interference of air bubbles. The three different approaches that were studied included a filament polylactic acid cell using only fused filament fabrication (FFF), a resin cell printed using stereolitography (SLA), and finally a design made of copper, which was manufactured by combining metal injection moulding (MIM) with fused filament fabrication (FFF). Computational fluid dynamic (CFD) modelling was undertaken using ANSYS Fluent V18.1 to provide insight into the flow of heat within the measurement cell, facilitating optimisation of the system and theoretical response speed.It was shown that the measurement cells using SLA had the lowest noise (~ 0.6%) and shortest measurement time (15 min), whereas measurement cells produced using other approaches had lower specificity or suffered from voiding issues. Finally, we assessed the potential of these new designs for detection of biomolecules and amoxicillin, a commonly used beta lactam antibiotic, to demonstrate the proof of concept. It can be concluded that the resin addition-type measurement cells produced with SLA are an interesting affordable alternative, which were able to detect amoxicillin with high sensitivity and have great promise for clinical applications due to the disposable nature of the measurement cells in addition to small sample volumes.

Land-use changes and precipitation cycles to understand hydrodynamic responses in semiarid Mediterranean karstic watersheds.

Non-planned agricultural land abandonment is affecting natural hydrological processes. This is especially relevant in vulnerable arid karstic watersheds, where water resources are scarce but vital for sustaining natural ecosystems and human settlements. However, studies assessing the spatiotemporal evolution of the hydrological responses considering land-use changes and precipitation cycles for long periods are rare in karstic environments. In this research, we selected a representative karstic watershed in a Mediterranean semiarid domain, since in this belt, karst environments are prone to land degradation processes due to human impacts. Geographic Information Systems-based tools and hydrological modeling considering daily time steps were combined with temporal analysis of climate variables (wavelet analysis) to demonstrate possible interactions and vulnerable responses. Observed daily flow data were used to calibrate/validate these hydrological models by applying statistic indicators such as the NSE efficiency and a self-developed index (the ANSE index). This new index could enhance goodness-of-fit measurements obtained with traditional statistics during the model optimization. We hypothesize that this is key to adding new inputs to this research line. Our results revealed that: i) changes in the type of sclerophyllous vegetation (Quercus calliprinos, ilex, rotundifolia, suber, etc.) from 81.5% during the initial stage (1990) to natural grasslands by 81.6% (2018); and, ii) decreases in agricultural areas (crops) by approximately 60% and their transformation into coniferous forests, rock outcrops, sparsely natural grasslands, etc. in the same period. Consequently, increases in the curve number (CN) rates were identified as a result of land abandonment. As a result, an increase in peak flow events jointly with a relevant decrease of the average flow rates (water scarcity) in the watershed was predicted by the HEC-HMS model and verified through the observed data. This research provides useful information about the effects of anthropogenic changes in the hydrodynamic behaviour of karstic watersheds and water resource impacts, especially key in water-scarce areas that depict important hazards for the water supply of related populations and natural ecosystems.

A review on recent developments in hydrodynamic cavitation and advanced oxidative processes for pretreatment of lignocellulosic materials.

Environmental problems due to utilization of fossil-derived materials for energy and chemical generation has prompted the use of renewable alternative sources, such as lignocellulose biomass (LB). Indeed, the production of biomolecules and biofuels from LB is among the most important current research topics aiming to development a sustainable bioeconomy. Yet, the industrial use of LB is limited by the recalcitrance of biomass, which impairs the hydrolysis of the carbohydrate fractions. Hydrodynamic cavitation (HC) and Advanced Oxidative Processes (AOPs) has been proposed as innovative pretreatment strategies aiming to reduce process time and chemical inputs. Therefore, the underlying mechanisms, procedural strategies, influence on biomass structure, and research gaps were critically discussed in this review. The performed discussion can contribute to future developments, giving a wide overview of the main involved aspects.