A steady-state pH-control model for the biological production of elemental sulfur from sulfate in mining-influenced water.

We developed a model to predict pH, alkalinity, and the Langelier Saturation Index (LSI) in coupled systems of hydrogen-based autotrophic sulfate reduction and aerobic oxidation of sulfide to elemental sulfur. To neutralize the biologically generated base, the model allows for the addition of CO as part of the gas mixture, the independent addition of HCl or CO, or a combination of the alternatives. The model was evaluated against the results from a laboratory system for the production of elemental sulfur from sulfate present in mine-tailings water, which is characterized by the presence of elevated sulfate and calcium concentrations.

Optimization of the chemolithotrophic denitrification of ion exchange concentrate using hydrogen-based membrane biofilm reactors.

A H-based membrane biofilm reactor (MBfR) was used to remove nitrate from a synthetic ion-exchange brine made up of 23.8 g L NaCl. To aid the selection of the best nitrate management strategy, our research was based on the integrated analysis of ionic exchange and MBfR processes, including a detailed cost analysis.

A large-scale neurocomputational model of spatial cognition integrating memory with vision.

We introduce a large-scale neurocomputational model of spatial cognition called 'Spacecog', which integrates recent findings from mechanistic models of visual and spatial perception. As a high-level cognitive ability, spatial cognition requires the processing of behaviourally relevant features in complex environments and, importantly, the updating of this information during processes of eye and body movement. The Spacecog model achieves this by interfacing spatial memory and imagery with mechanisms of object localisation, saccade execution, and attention through coordinate transformations in parietal areas of the brain.

Binding of Pentagalloyl Glucose to Aortic Wall Proteins: Insights from Peptide Mapping and Simulated Docking Studies.

Pentagalloyl glucose (PGG) is currently being investigated as a non-surgical treatment for abdominal aortic aneurysms (AAAs); however, the molecular mechanisms of action of PGG on the AAA matrix components and the intra-luminal thrombus (ILT) still need to be better understood. To assess these interactions, we utilized peptide fingerprinting and molecular docking simulations to predict the binding of PGG to vascular proteins in normal and aneurysmal aorta, including matrix metalloproteinases (MMPs), cytokines, and fibrin. We performed PGG diffusion studies in pure fibrin gels and human ILT samples.

High-Rate Sulfate Removal Coupled to Elemental Sulfur Production in Mining Process Waters Based on Membrane-Biofilm Technology.

It is anticipated that copper mining output will significantly increase over the next 20 years because of the more intensive use of copper in electricity-related technologies such as for transport and clean power generation, leading to a significant increase in the impacts on water resources if stricter regulations and as a result cleaner mining and processing technologies are not implemented. A key concern of discarded copper production process water is sulfate. In this study we aim to transform sulfate into sulfur in real mining process water.

Evaluation of percrystallization coupled with electrodialysis for zero liquid discharge in the pulping industry.

We evaluated percrystallization at laboratory scale to determine its suitability as core technology for achieving Zero Liquid Discharge (ZLD) in a Kraft effluent desalination process. Compared with conventional evaporation/crystallization techniques, percrystallization allows to operate at room temperature and with barely pressurized fluids, using relatively unexpensive membranes and vacuum to allow evaporation of aqueous brine solutions. For further comprehension of the technology before experimentation, a computational fluid dynamics model was developed, showing how temperature affects the performance of percrystallization in terms of transmembrane flux.

Optimal attention tuning in a neuro-computational model of the visual cortex-basal ganglia-prefrontal cortex loop.

Visual attention is widely considered a vital factor in the perception and analysis of a visual scene. Several studies explored the effects and mechanisms of top-down attention, but the mechanisms that determine the attentional signal are less explored. By developing a neuro-computational model of visual attention including the visual cortex-basal ganglia loop, we demonstrate how attentional alignment can evolve based on dopaminergic reward during a visual search task.

Long-term operation of a permeable reactive barrier with diffusive exchange.

In this study, we evaluate the long term operation of a bench-scale reactor which simulates a permeable reactive barrier with sulfidic diffusive exchange (SDES PRB) to treat acid mine drainage (AMD), considering that treatment costs are very sensitive to the useful life for passive reactors. Its functioning was evaluated for a much longer period of 591 days compared to previous SDES PRB studies, with two influents simulating moderately and highly acid groundwater contaminated by AMD. First, we fed water amended with 200 mg/L Zn and 3300 mg/L SO at pH 4.

High frequency pulsed electrodialysis of acidic filtrate in kraft pulping.

We introduce high frequency pulsed electrodialysis (hf-pED) to process the acidic filtrate of a Kraft pulp bleaching stage, tested in a pilot trial. Compared with conventional electrodialysis, hf-pED at 2,000 Hz allows a reduction in operational cost by 12%, estimated as 0.54 USD/m of acidic filtrate, while simultaneously preventing membrane fouling.

A membrane-biofilm system for sulfate conversion to elemental sulfur in mining-influenced waters.

A system of two membrane biofilm reactors (MBfRs) was tested for the conversion of sulfate (1.5 g/L) in mining-process water into elemental sulfur (S) particles. Initially, a H-based MBfR reduced sulfate to sulfide, and an O-based MBfR then oxidized sulfide to S.

gen. nov., sp. nov., an acidophilic and obligately heterotrophic, member of the Actinobacteria that catalyses dissimilatory oxido-reduction of iron isolated from metal-rich acidic water in Chile.

A novel acidophilic member of the phylum was isolated from an acidic, metal-contaminated stream draining from an abandoned underground coal mine (Trongol mine), situated close to Curanilahue, Biobío Region, Chile. The isolate (USS-CCA1) was demonstrated to be a heterotroph that catalysed under aerobic conditions the oxidation of ferrous iron and the reduction of ferric iron under anaerobic conditions, but not the oxidation of sulfur nor hydrogen. USS-CCA1 is a Gram-positive, motile, short rod-shaped, mesophilic bacterium with a temperature growth optimum at 30 °C (range 20-39 °C).

Influence of operating conditions on sulfate reduction from real mining process water by membrane biofilm reactors.

Two H-based membrane biofilm reactor (H-MBfR) systems, differing in membrane type, were tested for sulfate reduction from a real mining-process water having low alkalinity and high concentrations of dissolved sulfate and calcium. Maximum sulfate reductions were 99%, with an optimum pH range between 8 and 8.5, which minimized any toxic effect of unionized hydrogen sulfide (HS) on sulfate-reducing bacteria (SRB) and calcite scaling on the fibers and in the biofilm.

Evaluation of the bio-protection mechanism in diffusive exchange permeable reactive barriers for the treatment of acid mine drainage.

This research studied the bio-protection mechanism based on chemical gradients in diffusive exchange permeable reactive barriers, evaluating the thickness of the reactive layers in the treatment of concentrated acid mine drainage (AMD). Six bench-scale reactors were constructed with reactive layer thicknesses of 2.5, 5, and 7.

Performance of two differently designed permeable reactive barriers with sulfate and zinc solutions.

For the first time, this laboratory-scale study evaluates the feasibility of incorporating diffusive exchange in permeable reactive barriers. In order to do this, the performance of two permeable reactive barriers (PRB) with different internal substrate arrangements were compared during the administration of a sulfate solution without metals (for 163 days) and with metals (for 60 days), simulating groundwater contaminated with acid mine drainage (AMD). In order to simulate a traditional PRB, a homogeneous distribution was implemented in the first reactor and the other PRB reactor utilized diffusion-active technology (DAPRB).

Pharmacokinetics and Safety of Risperidone Subcutaneous Implants in Stable Patients With Schizophrenia.

A subcutaneous risperidone implant (RI) formulation was developed to improve medication adherence in schizophrenia. Two phase 1 studies were conducted to evaluate the pharmacokinetics of RI in adult patients with schizophrenia. In study 1, all subjects were stable on 4 mg oral risperidone; subsequently, the first subject received 375 mg RI for 1 month, and the remaining subjects received 375 mg RI for 3 months.

Do subtoxic levels of chlorate influence the desiccation tolerance of Egeria densa?

Among the different factors hypothesized to be responsible for the virtual disappearance of Egeria densa, once a dominant aquatic macrophyte in a southern Chile wetland ecosystem, are the negative effects of certain chemical compounds (mainly chlorate) and harsh environmental conditions (desiccation caused by prolonged atmospheric exposure). The authors performed an integrated experiment in which E. densa plants were first exposed for four weeks inside a mesocosm system to levels of chlorate that existed in the wetland at the time of the plant's demise and then exposed to desiccation conditions that also resembled those that the system had experienced.

Chlorate reduction capacity and characterisation of chlorate reducing bacteria communities in sediments of the rio Cruces wetland in southern Chile.

This study investigated chlorate reduction kinetics in multiple samples of sediments from a longitudinal profile of a wetland located downstream of the effluent discharge of a cellulose plant, including characterisation of the bacterial communities involved. The sediments were exposed to different initial chlorate concentrations in microcosm tests, with and without the addition of acetate as an external electron donor, and in a matrix of natural water or a defined medium. At a high initial chlorate concentration of 100 mg/L, in the absence of an external electron source, the degradation curves presented first-order kinetics, influenced by electron donor availability.

Three-electrode self-actuating self-sensing quartz cantilever: design, analysis, and experimental verification.

We present a novel quartz cantilever for frequency-modulation atomic force microscopy (FM-AFM) which has three electrodes: an actuating electrode, a sensing electrode, and a ground electrode. By applying an ac signal on the actuating electrode, the cantilever is set to vibrate. If the frequency of actuation voltage closely matches one of the characteristic frequencies of the cantilever, a sharp resonance should be observed.

The diffusion-active permeable reactive barrier.

Using the biogeochemical model CCBATCH, which we expanded to include transport processes, we study a novel approach for the treatment of aquifers contaminated with toxic concentrations of metals, the diffusion-active permeable reactive barrier (DAPRB), which is based on generation of sulfide by Sulfate Reducing Bacteria (SRB) as the groundwater moves through a layered treatment zone. In the DAPRB, layers of low conductivity (low-K) containing reactive materials are intercalated between layers of high conductivity (high-K) that transport the groundwater across the barrier. Because diffusion dominates transport in the reactive layers, microbial communities can take advantage there of the chemical-gradient mechanism for protection from toxicants.

Modeling bio-protection and the gradient-resistance mechanism.

We expand the biogeochemical program CCBATCH to describe transport processes in 1-D ground-water systems. We use the expanded CCBATCH with our biogeochemical framework for metal detoxification in sulfidic systems to study complex bio-protection scenarios. In particular, in our numerical experiments we expose a consortium of sulfate-reducing bacteria and fermenting bacteria to a toxic concentration of Zn(2+) in a 1-D system with precipitation of zinc-sulfide solids turned off or on.

A biogeochemical framework for metal detoxification in sulfidic systems.

We develop a comprehensive biogeochemical framework for understanding and quantitatively evaluating metals bio-protection in sulfidic microbial systems. We implement the biogeochemical framework in CCBATCH by expanding its chemical equilibrium and biological sub-models for surface complexation and the formation of soluble and solid products, respectively. We apply the expanded CCBATCH to understand the relative importance of the various key ligands of sulfidic systems in Zn detoxification.

Production of radioactive particles for endovascular therapeutic interventions.

Recanalization is a common phenomenon that decreases the efficacy of embolization procedures. It can be inhibited by beta-radiation. Two novel ways of producing radioactive particles are described, by neutron beam irradiation of gold-containing microspheres, or by using the 32P binding capacity of zirconium-containing microspheres.