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Biomedical subjects

E Roca

Publications and source records attributed to E Roca.

At least 19 recordsLinked to original sources
PubMed2006

Integrated pollution prevention and control for heavy ceramic industry in Galicia (NW Spain).

The heavy ceramic industry (building materials and refractory products manufacture) is an important source of pollutants to the environment. For this reason these industrial sub-sectors are included in prevention and control pollution policies, specifically those of the European Union. The IPPC Directive pays particular attention to the mineral industries, not least to the ceramic industry (epigraph 3.5, Annex I). In this paper, a methodology which is being applied to support IPPC installations and the competent administrative authority in Galicia (NW Spain) is presented. For that, the Galician heavy ceramic industry is analysed, as also are the ways to study the Best Available Techniques (BAT) with a view to establishing the emission limit values (ELV) for each specific case. Hence, a technological state of the art has been carried out for both sub-sectors, from the point of view of implementation of the IPPC in Galicia. Following this, the processes are described briefly and an analysis of the consumption and emission levels of the main pollutants is made. An inventory that includes the best environmental practices and the preventive and abatement candidate techniques as BAT was elaborated for both considered sub-sectors. An information data sheet for each candidate BAT is presented as a method to help both the industries and the competent authority to identify a candidate technique of the inventory as BAT. Three illustrative examples of the application of this procedure are presented for different emissions to environmental media for Galician installations.

Ceramics↗
PubMed2006

Granulation in high-load denitrifying upflow sludge bed (USB) pulsed reactors.

In this work, the effect of the application of a pulse system to anoxic upflow sludge bed (USB) denitrifying reactors for enhancing sludge granulation was studied. In all, three 0.8 L reactors (two operated with flow pulsation, P1 with effluent recycling and P2 without recycling, and one without pulsation and effluent recycling, no pulsation (NP)) were fed with a mixture of NaNO3 and glucose and inoculated with methanogenic granular sludge. The organic loading rate (OLR) and the nitrogen loading rate (NLR) were progressively increased and, at the end of the experiment, extremely high values were obtained (67.5 kgCOD/m3d and 11.25 kgN-NO3-/m3 d). Ammonia and nitrite accumulation in reactor NP were important in the maturation stage, decreasing the denitrification efficiency to 90%, while in reactor P1 only low nitrite values were obtained in the last few days of the experiment. In reactor P2, nitrogen removal was 100% most of the time. Several operational problems (flotation and the subsequent wash out of biomass) appeared in the NP reactor when working at high denitrifying loading rates, while in reactors P1 and P2 there were no notable problems, mainly due to the good characteristics of the sludge developed and the efficient degasification produced by the pulsing flow. The sludge formed in the NP reactor presented a flocculent structure and a total disintegration of the initial methanogenic granules occurred, while a small-sized granular biomass with a high specific density was developed in the pulsed reactors due to the shear stress produced.

Ammonia↗
PubMed2006

A hydrogen-based variable-gain controller for anaerobic digestion processes.

An easy-to-implement controller based on gas phase measurements for anaerobic digestion processes was developed. The controller is based on the indirect control of COD in the effluent by means of controlling the hydrogen concentration in the biogas. The fast response of hydrogen under destabilizations, such as those caused by overloads, guarantees an early actuation on the system before it destabilizes. The controller is designed such that it brings the anaerobic digestion process to maximum capacity by pushing it to maximum methane production as long as hydrogen remains low. Experiments have been conducted to test the controller under organic over- and underload situations and promising performance was achieved. Further experiments must be carried out to validate the controller under a wider spectrum of situations to enable its robust industrial application.

Anaerobiosis↗
PubMed2005

An integrated system to remote monitor and control anaerobic wastewater treatment plants through the internet.

The TELEMAC project brings new methodologies from the Information and Science Technologies field to the world of water treatment. TELEMAC offers an advanced remote management system which adapts to most of the anaerobic wastewater treatment plants that do not benefit from a local expert in wastewater treatment. The TELEMAC system takes advantage of new sensors to better monitor the process dynamics and to run automatic controllers that stabilise the treatment plant, meet the depollution requirements and provide a biogas quality suitable for cogeneration. If the automatic system detects a failure which cannot be solved automatically or locally by a technician, then an expert from the TELEMAC Control Centre is contacted via the internet and manages the problem.

Automation↗
PubMed2004

Anaerobic and aerobic continuous cultures of Saccharomyces cerevisiae: comparison of plasmid stability and EXG1 gene expression.

Two bioreactor continuous cultures, at anaerobic and aerobic conditions, were carried out using a recombinant Saccharomyces cerevisiae strain that over-expresses the homologous gene EXG1. This recombinant system was used to study the effect of dissolved oxygen concentration on plasmid stability and gene over-expression. Bioreactor cultures were operated at two dilution rates (0.14 and 0.03 h(-1)) to investigate the effect of other process parameters on EXG1 expression. Both cultures suffered severe plasmid instability during the first 16 generations. Segregational plasmid loss rate for the aerobic culture was two-fold that of the anaerobic operation. In spite of this fact, exo-beta-glucanase activity at aerobic conditions was 12-fold that of the anaerobic culture. This maximal activity (30 U ml(-1)) was attained at the lowest dilution rate when biomass reached its greatest value and glucose concentration was zero.

Aerobiosis↗
PubMed2003

Improvement of the properties of granular sludge in UASB reactors by flow pulsation.

The objective of this work is to improve the characteristics of granular sludge by modification of the hydraulics of the bed through flow pulsation. Three UASB reactors, two operated with pulsing flow (P1 and P2) and a third without pulsation (NP), were started-up. Both recycling and feeding flow were pulsed in the reactor P1, while in reactor P2, only the feeding was pulsed. A high increase in the removal capacity and stability were achieved by applying pulsation in reactors P1 and P2 when compared to the non-pulsed one. Besides, pulsation promotes the formation of particles of smaller size and higher porosity, thus increasing the specific surface of the bed and consequently, the specific activity. In fact, while reactors P1 and P2 had a 95% COD removal when working at high organic loading rates (12 kg COD/m3 x d), reactor NP only reached 6 kg COD/m3 x d with 85% of removal capacity.

Biomass↗
PubMed2002

An expert system for monitoring and diagnosis of anaerobic wastewater treatment plants.

In this paper, an expert system (ES) developed for the monitoring and diagnosis of anaerobic wastewater treatment plants (AWT), is presented. The system was evaluated in a hybrid pilot plant of 1.1 m3 located in an industrial environment for the treatment of wastewaters from a fibreboard production factory. The reactor is a hybrid USBF, combining an upflow anaerobic sludge blanket (UASB) in the lower part and an upflow anaerobic filter (UAF) at the top.

Bacteria, Anaerobic↗
PubMed2002

Influence of pulsation on start-up of UASB reactors.

The aim of this work is to study the influence of pulsation on the start-up of lab-scale UASB reactors. Pulsation was produced by an Elastic Membrane Pulsator (EMP). The application of this device in previous works improved the performance of continuous fixed-bed fermentors and reduced the formation of preferential pathways, the retention of gas metabolites within the bed and the resistance to mass transfer. These characteristics seem to be suitable for feeding UASB reactors. In this work, the influence of pulsation frequency was studied in two pulsed UASB reactors operated in parallel with a non-pulsed one. One of them (P1) operated at high frequencies (periods of 50 and 200 s between each pulsation) and the other (P2) at low frequencies (periods of 3600 and 900 s between each pulsation). An important improvement of the removal efficiency for pulsed reactors with respect to the non-pulsed one was obtained. The structure of the biomass was observed at the end of the process by scanning electron microscopy. In general, granulation of biomass was improved when operating in pulsing form.

Bacteria, Anaerobic↗
PubMed2002

Expert system for the on-line diagnosis of anaerobic wastewater treatment plants.

A diagnosis system for anaerobic wastewater treatment processes is presented. The system is able to recognise the state and trend of the operation and suggest the appropriate control action. The on-line variables measured were gas flow rate and composition (methane and carbon monoxide), feed and recycling flow rates, temperature and pH, while the manipulable inputs are feed, recycling and buffer-addition flow rates. The diagnosis system comprises a structured rule base, incorporating expert knowledge using fuzzy logic features. The structure of the system is based on the classification of information related to the process in three categories: i) the state of the process, ii) its trend and iii) the recommended set-point values for the inputs manipulated: feeding, buffer and recycling pumps. The system was applied to diagnose the operation of a 1.1 m3 hybrid UASB-UAF treating wastewater from a fibreboard production factory under different conditions (overload and underload), corresponding to some of the typical causes of destabilisation in anaerobic wastewater treatment plants. These situations require control action in order to maintain the stability and the treatment capacity of the reactor. The application of the system developed for the purpose of managing the situation proved to be reliable for supplying the actual state and trend of the process, as well as the adequate set point values to recover stable operation and/or to avoid further destabilisation.

Bacteria, Anaerobic↗
PubMed2001

Advanced monitoring and control of anaerobic wastewater treatment plants: diagnosis and supervision by a fuzzy-based expert system.

A fuzzy-based expert system (ES) for the diagnosis and supervision for anaerobic digesters is presented. The system was developed in a Microsoft Windows support using fuzzy logic inference together with a rule base for the implementation of expert knowledge. The ES runs on-line through three main modules, which determine the state and trend of the process, and the best set points for the actuation on the final control elements of the plant. Two further modules run in parallel, when they are required by the operator, using off-line and on-line information for the detection of inhibition due to toxic compounds in the process and for the validation of the on-line diagnosis. The diagnosis and supervision ES was tuned up in order to adjust the membership functions describing the process, and lately tested, running on-line, to study the response of the rule base.

Anaerobiosis↗
PubMed1999

Use of cheese whey as a substrate to produce manganese peroxidase by Bjerkandera sp BOS55.

Manganese peroxidase, MnP, is one of the major ligninolytic enzymes produced by a number of white-rot fungi. The ability of this enzyme to degrade lignin by the fungus Bjerkanderasp BOS55 has opened its application to related bioprocesses such as recalcitrant-compound degradation and effluent decolorization. The medium reported to induce MnP production is composed of chemical grade reagents, all with relatively high costs for application to detoxification purposes. The use of inexpensive sources for MnP production can bring its implementation closer. For this purpose, dairy residues from cheese processing were considered. MnP production obtained using crude whey as the sole substrate reached appreciable levels, around 190 U L-1, values comparable to those found with synthetic media (between 175-250 U L-1). Thus, this cheese-processing byproduct can be used as an inexpensive alternative for the large-scale production of MnP.

Journal Article↗
PubMed1999

Xylitol production from wood hydrolyzates by entrapped Debaryomyces hansenii and Candida guilliermondii cells.

Debaryomyces hansenii cells were entrapped in Ca-alginate beads and used for producing xylitol from wood hydrolyzates. Batch experiments showed that bioconversion was severely hindered when Ca-alginate beads were hardened with Al3+ solutions. As an alternative to Al3+ hardening, the improvements in both mechanical stability of bioparticles and fermenting ability of the immobilized system derived from using increased concentrations of sodium alginate were assessed. The best results were obtained using a 4% (w/v) Na-alginate solution in the gelification step. This concentration was selected to perform continuous fermentations in a packed-bed reactor using raw or charcoal-treated hydrolyzates (15.5 g of xylose/L) with two different yeasts: Candida guilliermondii and Debaryomyces hansenii. With a final cell concentration of about 50 g of cells/L (0.075 g of cells/g of beads), the volumetric productivities reached with these yeasts in media made from charcoal-treated hydrolyzates were 0.58 and 0.91 g/L.h, respectively.

Journal Article↗
PubMed1996

Combined intensive chemoradiotherapy for organ preservation in patients with resectable and non-resectable oesophageal cancer.

From January 1990 to April 1993, 60 oesophageal cancer patients were enrolled in a protocol of non-surgical treatment that consisted of induction chemotherapy followed by concurrent chemoradiotherapy. Induction chemotherapy consisted of cisplatin 40 mg/m2 intravenous bolus days 1, 2, 14, 15; 24 h continuous infusion of 5-fluorouracil (5-FU) 1000 mg/m2 days 1 and 14; leucovorin 20 mg/m2 days 1 and 14 given before and with 5-FU; bleomycin 30 UI days 1 and 14; mitomycin C 10 mg/m2 day 14. Concurrent chemoradiotherapy consisted of 60 Gy (6 weeks) from day 21 and cisplatin 70 mg/m2 days 28, 42 and 56; leucovorin 20 mg/m2 followed by 5-FU 425 mg/m2 days 28, 35, 42, 49 and 56. Complete response occurred in 44 of 55 evaluable patients (80%). The median survival is 32 months; the actuarial survival at 40 months is 35% (CI 18-53). These results appear improved over those reported with surgery or radiation alone, and suggest that organ preservation as a secondary treatment goal should be vigorously investigated.

Adult↗
PubMed1996

Tallimustine in advanced previously untreated colorectal cancer, a phase II study.

Tallimustine is a novel benzoyl mustard derivative from distamycin A with a unique mode of action. It is a DNA minor groove binder and produces highly sequence-specific alkylations. Previous studies have shown significant anti-tumour effects in animal models. We performed a phase II study in previously untreated patients with advanced colorectal cancer, using a schedule of i.v. bolus infusions of 900 microgram m-2 once every 4 weeks. Seventeen patients were enrolled, and no responses were documented in 14 evaluable patients. Toxicity mainly consisted a highly selective neutropenia, which warrants further investigation of this agent in combination with myeloid growth factors.

Adult↗
PubMed1996

Rapid assessment of drug consumption at Santa Cruz de la Sierra, Bolivia.

The present paper describes a rapid assessment carried out in 1996 at Santa Cruz de la Sierra, Bolivia, with a view to defining the sociocultural groups at risk and gaining insight, through the comments of those interviewed, into their perceptions of the phenomenon of drug abuse, their reasons for abusing drugs, the drugs most frequently abused and the psychological and social factors involved when they enter, remain in and finally leave drug-abusing circles. By using qualitative methodology and techniques it was possible to gain access to the typical world inhabited by the interviewees, and thus to characterize the subjects of the study in the light of their closest social reference points (family, peer group, education and work). Among the conclusions of the study are the following: drug abuse is a complex and dynamic phenomenon that has occurred throughout the society of Santa Cruz, fostered by cultural and economic factors; there is a need for society, and especially the Government, to devise a specific, focused and diversified range of services, both in prevention and in rehabilitation, with integration and participation being key features of such initiatives; and the mechanisms for controlling the production of drugs and drug trafficking need to be strengthened.

Adolescent↗
PubMed1995

[Medical treatment of 44 patients with anal canal carcinoma. Argentinian Intergroup for the treatment of gastrointestinal tumors (IATTGI)].

In order to investigate the medical treatment of anal canal carcinoma (ACC), 27 patients (pts) were treated with cisplatin, fluorouracil and radiotherapy, in an alternating schedule. Eleven pts received mitomycin C, fluorouracil and radiotherapy, in a concurrent scheme. Finally, six pts were included in a new outpatient scheme with cisplatin, fluorouracil, leucovorin, mitomycin C and concurrent radiotherapy. Within the first schedule, 25 pts were evaluable and 18 achieved complete response. All of them are disease free until now. With the second scheme, 7/10 pts had a complete response and 5 of them are alive and disease free. All the pts included in the last schedule (6/6) achieved complete remission. There were no deaths related to toxicity. Our experience is one of the earliest in oncology using cisplatin as a first line drug, in the non-surgical treatment of ACC. We think that the use of cisplatin is feasible, its toxicity is manageable, and its effectivity is similar to other schedules, as observed in our last scheme.

Adult↗