Protein Crystallization in a Microfluidic Contactor with Nafion®117 Membranes.

Protein crystallization still remains mostly an empirical science, as the production of crystals with the required quality for X-ray analysis is dependent on the intensive screening of the best protein crystallization and crystal's derivatization conditions. Herein, this demanding step was addressed by the development of a high-throughput and low-budget microfluidic platform consisting of an ion exchange membrane (117 Nafion® membrane) sandwiched between a channel layer (stripping phase compartment) and a wells layer (feed phase compartment) forming 75 independent micro-contactors. This microfluidic device allows for a simultaneous and independent screening of multiple protein crystallization and crystal derivatization conditions, using Hen Egg White Lysozyme (HEWL) as the model protein and Hg2+ as the derivatizing agent. This microdevice offers well-regulated crystallization and subsequent crystal derivatization processes based on the controlled transport of water and ions provided by the 117 Nafion® membrane. Diffusion coefficients of water and the derivatizing agent (Hg2+) were evaluated, showing the positive influence of the protein drop volume on the number of crystals and crystal size. This microfluidic system allowed for crystals with good structural stability and high X-ray diffraction quality and, thus, it is regarded as an efficient tool that may contribute to the enhancement of the proteins' crystals structural resolution.

Predicted concentrations of anticancer drugs in the aquatic environment: What should we monitor and where should we treat?

Anticancer drugs have been detected in the aquatic environment, they have a potent mechanism of action and their consumption is expected to drastically increase in the future. Consequently, it is crucial to routinely monitor the occurrence of anticancer drugs and to develop effective treatment options to avoid their release into the environment. Prior to implementing a monitoring program, it is important to define which anticancer drugs are more prone to be found in the surface waters. In this study the consumption of anticancer drugs in the Lisbon region (Portugal), Belgium and Haryana state (India) were used to estimate the concentrations that can be expected in surface waters. Moreover, one important aspect is to define the major entry route of anticancer drugs in the aquatic environment: is it hospital or household effluents? The results disclosed in this study showed that in Belgium and Lisbon, 94 % of the total amount of anticancer drugs were delivered to outpatients, indicating that household effluents are the primary input source of these drugs and thus, upgrading the treatment in the domestic wastewater facilities should be the focus.

Pilot scale nanofiltration treatment of olive mill wastewater: a technical and economical evaluation.

The treatment of large volumes of olive mill wastewater is presently a challenge. This study reports the technical and economical feasibility of a sequential treatment of olive mill wastewater comprising a dissolved air flotation pre-treatment and nanofiltration. Different pilot nanofiltration assays were conducted in a concentration mode up to different volume reduction factors (29, 45, 58, and 81). Data attained demonstrated that nanofiltration can be operated at considerably high volume reduction factors and still be effective towards the removal of several components. A flux decline of approximately 50% was observed at the highest volume reduction factor, mainly due to increase of the osmotic pressure. Considerably high rejections were obtained across all experiments for total suspended solids (83 to >99%), total organic carbon (64 to 99%), chemical oxygen demand (53 to 77%), and oil and grease (67 to >82%). Treated water was in compliance with European legal limits for discharge regarding total suspended solids and oil and grease. The potential recovery of phenolic compounds was evaluated and found not relevant. It was demonstrated that nanofiltration is economically feasible, involving operation costs of approximately 2.56-3.08 €/m3, depending on the working plan schedule and volume reduction factor, and requiring a footprint of approximately 52 m2 to treat 1000 m3 of olive mill wastewater.

Development of fluorescent thermoresponsive nanoparticles for temperature monitoring on membrane surfaces.

In this work, tris(phenantroline)ruthenium(II) chloride (Ru(phen)3) was immobilized in silica nanoparticles prepared according to the Stöber method. Efforts were devoted on the optimization of the nano-thermometer in terms of size, polydispersity, intensity of the emission and temperature sensitivity. In particular, the immobilization of the luminophore in an external thin shell made of silica grown in a second step on bare silica nanoparticles allowed producing fluorescent monodisperse silica nanoparticles (420±20nm). A systematic study was addressed to maximize the intensity of the emission of the fluorescent nanoparticles by adjusting the concentration of Ru(phen)32+ in the shell from 0.2 to 24wt.%, whereas the thickness of the shell is affected by the amount of silica precursor employed. The luminescent activity of the doped nanoparticles was found to be sensitive to the temperature. In fact, the intensity of the emission linearly decreased by increasing the temperature from 20°C to 65°C. The thermoresponsive nanoparticles were functionalized with long aliphatic chains in order to obtain hydrophobic nanoparticles. The developed nanoparticles were immobilized via dip-coating procedure on the surface of hydrophobic porous membranes, such as Polyvinylidene fluoride (PVDF) prepared via Non-Solvent Induced Phase Separation (NIPS), providing local information about the membrane surface temperature.

Multivariate analysis of the transport in an ion exchange membrane bioreactor for removal of anionic micropollutants from drinking water.

The present study focuses on investigating the effects of biological compartment conditions on the transport of nitrate and perchlorate in an Ion Exchange Membrane Bioreactor (IEMB). In this hybrid process, the transport depends not only on the membrane properties but also on the biological compartment conditions. The experiments were planned according to the Plackett-Burman statistical design in order to cover a broader range of experimental conditions, under which a previously developed mechanistic transport model was not able to predict correctly the transport fluxes of the target pollutants. Using Principal Component Analysis, it was possible to identify not only the concentrations of target (nitrate and perchlorate) and of major driving counter-ion (chloride) but also those of some biomedium components (e.g. ammonia, ethanol and sulphate) as variables that affect the transport rate of micropollutants across the membrane. These conclusions are based on the loadings of the two first principal components that describe 84% of the data variance. The present study also revealed that the hydraulic retention time and the hydrodynamic conditions in the biocompartment have a minor contribution to the micropollutants transport. The results obtained are important for process optimization purposes.

Real-time monitoring of membrane bioreactors with 2D-fluorescence data and statistically based models.

The application of membrane bioreactors (MBR) for wastewater treatment is growing worldwide due to their compactness and high effluent quality. However, membrane fouling, mostly associated to biological products, can reduce MBR performance. Therefore, it is important to monitor MBRs as close to real-time as possible to accelerate control actions for maximal biological and membrane performance. 2D-fluorescence spectroscopy is a promising on-line tool to simultaneously monitor wastewater treatment efficiency and the formation of potential biological fouling agents. In this study, 2D-fluorescence data obtained from the wastewater and the permeate of a MBR was successfully modelled using projection to latent structures (PLS) to monitor variations in the influent and effluent total chemical oxygen demand (COD). Analysis of the results also indicated that humic acids and proteins highly contributed to the measured COD in both streams. Nevertheless, this approach was not valid for other performance parameters of the MBR system (such as influent and effluent ammonia and phosphorus), which is usually characterised through a high number of analytical and operating parameters. Principal component analysis (PCA) was thus used to find possible correlations between these parameters, in an attempt to reduce the analytical effort required for full MBR characterisation and to reduce the time frame necessary to obtain monitoring results. The 3 first principal components, capturing 57% of the variance, indicated and confirmed expected relationships between the assessed parameters. However, this approach alone could not provide robust enough correlations to enable the elimination of parameters for process description (PCA loadings ≤ 0.5). Nevertheless, it is possible that the information captured by 2D-fluorescence spectroscopy could replace some of the analytical and operating parameters, since this technique was able to successfully describe influent and effluent total COD. It is thus proposed that combined modelling of 2D-fluorescence data and selected performance/operating parameters should be further explored for efficient MBR monitoring aiming at rapid process control.

The effect of carbon source on the biological reduction of ionic mercury.

Mercury (Hg) is the most highly toxic heavy metal, and must be removed from waterways to very low levels. Biologically mediated mercury removal is an emerging technology that has the potential to be robust, efficient and cost-effective. In this study, the impact of carbon source on the behaviour and microbial community composition of mixed microbial cultures was evaluated, and their performance was compared with a pure culture of Pseudomonas putida spi3. Glucose and acetate, two carbon sources that are commonly present in wastewaters, were chosen for this study. Distinct microbial populations were enriched with each carbon source. Glucose led to a more suitable microbial culture for Hg(2+) bioreduction that was able to reduce Hg(2+) at faster rates when compared to acetate. Furthermore, acetate consistently led to poorer process performance, irrespective of the microbial culture, possibly due to the formation of mercuric acetate complexes. It is proposed that glucose can be a more beneficial carbon source than acetate for the successful operation of Hg bioremediation systems.

Mating behavior of the hematophagous bug Triatoma infestans: role of Brindley's and metasternal glands.

We investigated if Brindley's and metasternal glands are involved in the sexual behavior of Triatoma infestans. In laboratory assays, we analyzed the effect of selective occlusion of Brindley's and metasternal glands of the female (separately and together) on the behavior of males. Control assays without occlusion of glands were also performed. We quantitatively tested if such glands affect mating occurrence, the copulatory attempts of males, and the aggregation of males around a mating couple. The number of mating attempts by males did not differ between treatments, demonstrating that likelihood of males mating did not depend on which gland is occluded in the female. In the absence of any occlusion, T. infestans mated and males aggregated. The proportion of copulations and aggregation behavior of males did not differ between treatments when female's Brindley's glands were occluded. However, when metasternal glands were occluded, the proportion of mating couples decreased and males did not aggregate. We demonstrated that the metasternal glands of the female are involved in the sexual behavior of T. infestans, while Brindley's glands seem to have no effect on mating behavior. Copulation and aggregation behavior of males likely result from the eventual release of volatiles from the female's metasternal glands.

Type 2 diabetes and tuberculosis in a dynamic bi-national border population.

The epidemic of type 2 diabetes in the United States prompted us to explore the association between diabetes and tuberculosis (TB) on the South Texas-Mexico border, in a large population of mostly non-hospitalized TB patients. We examined 6 years of retrospective data from all TB patients (n=5049) in South Texas and northeastern Mexico and found diabetes self-reported by 27.8% of Texan and 17.8% of Mexican TB patients, significantly exceeding national self-reported diabetes rates for both countries. Diabetes comorbidity substantially exceeded that of HIV/AIDS. Patients with TB and diabetes were older, more likely to have haemoptysis, pulmonary cavitations, be smear positive at diagnosis, and remain positive at the end of the first (Texas) or second (Mexico) month of treatment. The impact of type 2 diabetes on TB is underappreciated, and in the light of its epidemic status in many countries, it should be actively considered by TB control programmes, particularly in older patients.

Modelling of the extractive membrane bioreactor process based on natural fluorescence fingerprints and process operation history.

A method for non-mechanistic and non-linear modelling of complex biological processes is presented, using the example of the extractive membrane bioreactor (EMB). The model is based on artificial neural networks (ANN), which are able to predict the state of the process from a combination of reactor operational parameters and natural fluorescence fingerprints. Current as well as historic process operation is included in the ANN input vector, in order to account for lag-times within the reactor system and for biofilm dynamics that are dependent on process history. The model is especially relevant for practitioners, as it does not require assumptions on underlying process mechanisms, and it relies on routinely available operational data and on an easy-to-install, non-invasive, in-situ, on-line monitoring method. Moreover, it focuses on the prediction of overall process performance parameters, which are of immediate relevance in practice. The developed model was able to predict the process state very well. Sensitivity analysis revealed that the main impact on process performance stems from process operation rather than the physiological state of the biological culture, and that in the EMB configuration employed process operation history decisively impacts on the process outcome.

Monitoring of biofilm reactors using natural fluorescence fingerprints.

Natural fluorescence as a method to monitor biofilm processes was studied, using the example of an extractive membrane bioreactor for the degradation of 3-chloro-4 methylaniline and 1,2-dichloroethane. Non-invasive, on-line, in-situ 2D fluorometry monitoring was employed to elicit biofilm process status. The fluorescence fingerprints were deconvoluted in a pattern recognition approach using artificial neural networks (ANN) through association with key process performance parameters.

Organomercurial removal from vaccine production wastewaters in a supported liquid membrane bioreactor.

Vaccine production effluents are strongly polluted with thiomersal, a highly toxic organomercurial compound, for which there is presently no remediation technology available. This work describes a new remediation process based on the extraction of thiomersal from the wastewater to a biological compartment, where it is degraded by a microbial strain. The selective extraction of thiomersal is achieved by using an ionic liquid immobilized in a porous membrane. In the biological compartment, thiomersal is degraded to metallic mercury, under aerobic conditions, by a Pseudomonas putida strain. The utilization of ionic liquids in supported liquid membranes for thiomersal transport, and the kinetics of thiomersal biodegradation by a Pseudomonas putida strain are presented and discussed.

Two-dimensional fluorometry coupled with artificial neural networks: a novel method for on-line monitoring of complex biological processes.

The use of two-dimensional scanning fluorometry as an on-line, noninvasive, in situ bioreactor monitoring technique is extended to complex bioprocesses using mixed cultures, with particular attention to biofilm systems. Using the example of spectra subtraction, it is demonstrated that established methods for fluorescence data analysis have a limited capability of utilizing overall fluorometric information. Artificial neural networks (ANNs) are introduced as a novel nonlinear and nonmechanistic technique for interpreting the highly complex fluorescence maps. It is shown that ANNs are able to infer process performance parameters in a pattern recognition approach, based on the entire fluorescence "fingerprint" of the biological system. The studies were carried out using an extractive membrane bioreactor (EMB) for the degradation of chlorinated organic compounds, operating with mixed cultures. Model pollutants em- ployed were 1,2-dichloroethane, 3-chloro-4-methylaniline, and p-toluidine.

Selective recovery of solutes from ionic liquids by pervaporation--a novel approach for purification and green processing.

Non-porous membranes with the selective layer consisting of hydrophilic or hydrophobic polymers have been applied for the quantitative and selective recovery of solutes with different physico-chemical properties from a room-temperature ionic liquid, ([bmim][PF6]).

Mechanism of charged pollutants removal in an ion exchange membrane bioreactor: drinking water denitrification.

The mechanism of anionic pollutant removal in an ion exchange membrane bioreactor (IEMB) was studied for drinking water denitrification. This hybrid process combines continuous ion exchange transport (Donnan dialysis) of nitrate and its simultaneous bioreduction to gaseous nitrogen. A nonporous mono-anion permselective membrane precludes direct contact between the polluted water and the denitrifying culture and prevents secondary pollution of the treated water with dissolved nutrients and metabolic products. Complete denitrification may be achieved without accumulation of NO3(-) and NO2(-) ions in the biocompartment. Focus was given to the effect of the concentration of co-ions, counterions, and ethanol on the IEMB performance. The nitrate overall mass transfer coefficient in this hybrid process was found to be 2.8 times higher compared to that in a pure Donnan dialysis process without denitrification. Furthermore, by adjusting the ratio of co-ions between the biocompartment and the polluted water compartment, the magnitude and direction of each individual anion flux can be easily regulated, allowing for flexible process operation and control. Synthetic groundwater containing 135-350 mg NO3(-) L(-1) was treated in the IEMB system. A surface denitrification rate of 33 g NO3(-) per square meter of membrane per day was obtained at a nitrate loading rate of 360 g NO3(-) m(-3)d(-1), resulting in a nitrate removal efficiency of 85%.

[Burns in children. Experience of 53 cases (author's transl)]. / Quemaduras cutáneas infantiles. A propósito de 53 casos.

A series of 53 children admitted during a 20-month period to the Hospital for burns due to hot liquids is reported 88.6% were under three. 34 children were seen during spring and fall months. Most patients were recently burnt and in the majority of cases (27) burned surface was under 20%. l.v. fluids were used in 17 cases and management protocol included: Closed local care after the 3rd or 4th day with nitrofurazone cream and antibiotics only in selected cases. Mortality was 5.5% (three cases) due to acute renal failure at the 3rd, 5th and 10th days. 24.5% had a local infection in the first two weeks, gram negative bacteria being present in 75% of these cases. 33.2% (18 cases) required grafting. This was more frequently needed in boiling oil burns. In seven cases, grafting was necessary before the 30th day (average 23.2 days), and in the remaining patients after this time (average 42.1 days). Authors advise a strict prevention of acute rend failure and early grafting.