Isolated Medial Patellofemoral Ligament Reconstruction in Patellar Instability: Does the Distance Between Tibial Tuberosity-Trochlear Groove Make a Difference?

Introduction: Medial patellofemoral ligament reconstruction (MPFLR) is used in most patellar instability surgeries, there is controversy on adding a tibial tuberosity osteotomy (TTO). Objective: To describe the results of isolated MPFLR in patellar instability according to the Tibial Tuberosity-Trochlear Groove distance (TT-TG). Methods: Retrospective study of patients with patellar instability with a mature skeleton in one center between 2016 and 2021, using isolated MPFLR. Patients with incomplete clinical and/or radiological records and less than one year follow-up were excluded. Pre-surgical demographic and radiological data (TT-TG, Caton-Deschamps (CD) index, patellar tilt, trochlear dysplasia) were recorded. Patients were divided into three groups according to TT-TG distance (Group 1: < 17 mm, Group 2: 17-19, Group 3: ≥ 20 mm). A pre and post-surgical Kujala score was performed. Local complications, satisfaction, recurrence and/or reintervention were recorded. Pre-surgical variables between groups, intra and inter-group Kujala differences were compared using Bartlett's test. Consent from the patients and approval from the local ethics committee were obtained. Results: 67 patients met the selection criteria, mean age of 23 years, 70% were women. There were no pre surgical, radiological nor follow-up differences between the groups (average 27 months). Pre and post-surgical Kujala score, respectively: Group 1: 37-78, Group 2: 37-78, Group 3: 39-79. All groups had a significant improvement (p < 0.05), there were no significant differences in improvement between groups (p > 0.05). There were three patients with a redislocation episode, all in group 1. One patient had a mobilization under anesthesia due to an arthrofibrosis (Group 2). 97% of all cases reported being satisfied. Conclusion: Isolated MPFLR in patellar instability presents a functional improvement, with a low rate of complications and failure, regardless of the pre surgical TT-TG. Supplementary Information: The online version contains supplementary material available at 10.1007/s43465-023-00906-6.

Prenatal and Birth Care of Roma Women.

BACKGROUND: The reproductive health of Roma women has been poorly studied. It is important to determine the follow-up care received by Roma women from pregnancy to the first postpartum visit, together with neonatal outcomes, to improve prenatal care and maternal-child outcomes. OBJECTIVE: The aim of this study was to examine differences in prenatal care and maternal-infant outcomes between Roma and non-Roma women. METHODS: A retrospective longitudinal study was conducted in 122 pregnant women (28 Roma and 94 non-Roma women) recruited from seven primary care centers in three districts of Asturias (Spain). Sociodemographic variables, prenatal control, birth characteristics, feeding, and neonatal outcomes (gestational age, weight, and APGAR [appearance, pulse, grimace, activity, and respiration]) were collected from the electronic medical records. Prenatal care was assessed using three indices: the Kessner index, the Modified Adequacy of Prenatal Care Utilization Spanish Index, and an ad hoc index that considered adherence to the recommendations for pregnant women in Spain. RESULTS: Compared with non-Roma women, advanced maternal age (≥35 years) and primigravida were less common among Roma women. Roma women visited the dentist less often, smoked more, and underwent group B streptococcus screening less frequently. No differences were found in the number of prenatal visits between Roma and non-Roma women. Consequently, there were no differences between the Kessner index and the Modified Adequacy of Prenatal Care Utilization Spanish Index. Using the ad hoc index, the non-Roma women more frequently had adequate prenatal visits. There were no differences in birth characteristics, type of feeding, and neonatal outcomes. DISCUSSION: Overall, prenatal care was slightly worse in Roma women; however, this did not imply worse neonatal health outcomes. Both study groups had similar birth characteristics and immediate puerperium, including feeding.

Limitación auditiva y fragilidad social en hombres y mujeres mayores / Hearing loss and social frailty in older men and women

Objetivo: Explorar la asociación entre la limitación auditiva y la fragilidad social en una muestra de personas mayores de España. Método: Estudio transversal con una muestra de 445 personas (190 hombres y 255 mujeres) de 65 y más años de edad no institucionalizadas, reclutadas de centros de atención primaria en España. La limitación auditiva se determinó de forma autoinformada utilizando tres preguntas. Se consideró que existía fragilidad social cuando la persona presentó dos o más de las siguientes condiciones: vivir solo/a, ausencia de persona que brinde ayuda, contacto infrecuente con la familia, contacto infrecuente con amistades, falta de confidente y falta de ayuda para las actividades cotidianas en los últimos 3 meses. Para estudiar la asociación entre la limitación auditiva y la fragilidad social se realizaron modelos de regresión logística ajustados por posibles factores de confusión, incluyendo la presencia de fragilidad física. Resultados: La edad media de los/las participantes fue de 76,2 años (77,5 años para las mujeres). El 54,4% presentaban limitación auditiva y el 23,2% fueron considerados/as frágiles sociales. La limitación auditiva se asoció con la fragilidad social ( odds ratio ajustada [ORa]=1,78; intervalo de confianza del 95% [IC95%]: 1,043,06). No obstante, la asociación fue dependiente del sexo (p de interacción=0,041) y en los análisis estratificados la asociación solo se halló en las mujeres (ORa=3,21; IC95%: 1,447,17).Conclusiones: La limitación auditiva se asoció con fragilidad social en las mujeres, pero no en los hombres. Se precisan estudios longitudinales que confirmen esta asociación y ayuden a entender el efecto diferencial del sexo. (AU)

Objective: To explore the association between hearing loss and social frailty in a sample of Spanish older adults recruited from primary health care network.Method: Crosssectional study on a sample of 445 noninstitutionalized adults aged 65 or more years (190 men and 255 women), recruited from primary care centers in Spain. Three selfreported hearing impairment questions were used to assess hearing loss. Social frailty was deemed to exist when the person presented two or more of the following conditions: living alone, absence of a person to provide help, infrequent contact with family, infrequent contact with friends, lack of confident and lack of help for daily activities in the last 3 months. To study the association between hearing loss and social frailty we used logistic regression models adjusted for potential confounders, including physical frailty. Results: The mean age of participants was 76.2 years (77.5 years for women). More than half of the participants (54.4%) reported hearing loss and the frequency of social frailty was 23.2%. Hearing loss was associated with social frailty (adjusted odds ratio [aOR]=1.78; 95% confidence interval [95%CI]: 1.043.06). However, the association was sexdependent (p for interaction=0.041). In stratified analysis, the association was only found in women (aOR=3.21; 95%CI: 1.447.17). Conclusions: Hearing loss was associated with social frailty in women, but not in men. Longitudinal studies are needed to confirm this association and to understand the differential effect of gender. (AU)

Contribution of students to nursing practice settings during clinical training: Design and validation of a questionnaire.

BACKGROUND: A validated questionnaire to measure the contributions of nursing students to clinical settings could potentially assist in the improved management of students in healthcare institutions. AIM: To develop and test the psychometric properties of the questionnaire 'Nursing Student Contributions to Clinical Settings' (CEEEC, Spanish acronym for 'Contribuciones de los Estudiantes de Enfermería a los Entornos Clínicos'). DESIGN: Instrument design and psychometric testing. PARTICIPANTS/SETTINGS: A multicentre study involving 1,098 nursing professionals from three universities and five hospitals of Spain, between January 2019 and March 2020. METHODS: The study was carried out in two phases. Phase 1 involved the questionnaire design by experts (n = 28), which required a review of the available literature, cognitive interviews and Delphi rounds, and a preliminary validity study, which included a pilot test with responses from a sample of nurses (n = 143). Phase 2 involved a formal validation with a wider sample of nurses (n = 927), including factor analysis and a study of convergent validity with the Practice Environment Scale-Nursing Work Index and Health Sciences-Evidence Based Practice. RESULTS: Experts selected 42 items on student contributions. After cognitive interviews, three items were eliminated and seven failed to reach the minimum content validity index (78%). Based on the remaining 32 items, the discrimination index of each item was calculated, and those with <0.3, eight items were sequentially eliminated. The resulting questionnaire contained 24 items grouped into a single factor, which explained 41% of the variance. The internal consistency was excellent (Cronbach's alpha: 0.94), and the convergent validity was confirmed. CONCLUSIONS: A 24-item questionnaire was designed and validated to measure the contributions of nursing students to clinical practice settings. IMPACT: Most hospitals are also teaching centres where nursing students undergo clinical practice. The application of this test will provide insight into the nursing professionals' perception of the students' role.

[Hearing loss and social frailty in older men and women]. / Limitación auditiva y fragilidad social en hombres y mujeres mayores.

OBJECTIVE: To explore the association between hearing loss and social frailty in a sample of Spanish older adults recruited from primary health care network. METHOD: Cross-sectional study on a sample of 445 non-institutionalized adults aged 65 or more years (190 men and 255 women), recruited from primary care centers in Spain. Three self-reported hearing impairment questions were used to assess hearing loss. Social frailty was deemed to exist when the person presented two or more of the following conditions: living alone, absence of a person to provide help, infrequent contact with family, infrequent contact with friends, lack of confident and lack of help for daily activities in the last 3 months. To study the association between hearing loss and social frailty we used logistic regression models adjusted for potential confounders, including physical frailty. RESULTS: The mean age of participants was 76.2 years (77.5 years for women). More than half of the participants (54.4%) reported hearing loss and the frequency of social frailty was 23.2%. Hearing loss was associated with social frailty (adjusted odds ratio [aOR]=1.78; 95% confidence interval [95%CI]: 1.04-3.06). However, the association was sex-dependent (p for interaction=0.041). In stratified analysis, the association was only found in women (aOR=3.21; 95%CI: 1.44-7.17). CONCLUSIONS: Hearing loss was associated with social frailty in women, but not in men. Longitudinal studies are needed to confirm this association and to understand the differential effect of gender.

Return to play after anterior cruciate ligament reconstruction among amateur soccer players / Volver a jugar después del ligamento cruzado anterior reconstrucción entre futbolistas aficionados

OBJECTIVE: The aim of the present study is to assess the return to play among amateur soccer league players after anterior cruciate ligament (ACL) reconstruction. MATERIALS AND METHOD: The surgical protocols of ACL reconstruction surgeries performed in a sports medicine clinic from July 1st, 2013, to June 30th, 2014, were included in the study. Only the charts of amateur soccer league players who played once or twice a week were selected. The follow-up time was calculated as the number of months between surgery and the telephone survey. At the follow-up, the current status of the soccer playing was recorded. Those patients who were no longer playing in a team were asked what kind of sport they were currently practicing, as well as the main reason for not returning to team playing. RESULTS: A total of 61 (25.6%) patients met the inclusion criteria. The mean follow-up time was of 22.4 3.4 months. At the follow-up, 30 (49.1%) patients were playing in amateur soccer teams. Among the patients who were no longer playing in a team, 19 (61.2%) were playing soccer occasionally, 11 (35.4%) were practicing other sports, and 1 developed a sedentary life style. The reasons for not returning to team playing were: fear of reinjury in 26%; knee symptoms in 26%; lack of confidence in the knee in 23%, family or job commitments in 23%; and not being eligible to participate in competitive sports in 2%. CONCLUSION: After an average of two years of ACL reconstruction, only half of the amateur soccer league players return to play.

Impact of a Nurse Intervention to Improve Sleep Quality in Intensive Care Units: Results From a Randomized Controlled Trial.

BACKGROUND: Patients of adult intensive care units (ICUs) often suffer from a lack of sleep. Reducing anxiety by promoting adaptation to the ICU prior to admission may be an appropriate way to increase sleep quality. OBJECTIVE: The aim of this study was to evaluate the impact on sleep quality of a brief nurse intervention. METHODS: This was a pilot randomized controlled trial in Spain. Forty patients admitted in hospital for valve cardiac surgery were randomly allocated to (1) control group (n = 20), receiving usual care, and to (2) experimental group (EG, n = 20), receiving a nurse intervention the day before surgery and admission in the ICU. The intervention was based on Roy Adaptation Model. A trained nurse anticipated the stressful stimulus to patients in order to develop functional adaptive behaviors. A set of photographs and videos was used to illustrate the environment and assistance in the ICU. Sleep quality in the ICU was measured with the Richards-Campbell Sleep Questionnaire and usual sleep quality with the Pittsburgh Sleep Quality Index. RESULTS: After the intervention, sleep quality was lower in the EG compared with the control group (-4 points in Richards-Campbell Sleep Questionnaire, P = .69). Adjustment for main confounders led this reduction to -1.9 points (P = .87) among patients in EG. Stratified analyses shown a positive impact for people who usually slept well (+5.2 points, P = .77), but negative for those who had previous poor sleep quality (-20.0 points, P = .24). CONCLUSION: A nurse intervention prior to ICU admission did not increase patients' sleep quality. In addition, the intervention could have incremented anxiety over the patients who used to sleep poorly at their homes.

Arsenic, cadmium and lead in fresh and processed tuna marketed in Galicia (NW Spain): Risk assessment of dietary exposure.

Currently, metal bioaccumulation in fish is increasing and is a cause of concern due to toxicity. Total arsenic, cadmium and lead concentrations in fresh and processed tuna (110 samples) marketed in Galicia (NW Spain) were determined by ICP-MS spectrometry. The average concentrations of As and Cd, 3.78 and 0.024 mg kg-1 w.w., respectively, in fresh tuna were statistically significantly higher than those in processed tuna (p < 0.001). The contents in processed tuna were 0.295-7.85 mg kg-1 for As and ND-0.045 mg kg-1 for Cd. The Pb content was negligible in both types of tuna. In canned tuna, decreasing As and Cd concentrations were observed in different preparation-packaging media: olive oil > natural > pickled sauce. Of the two species studied in canned tuna, Thunnus alalunga showed statistically significant higher levels both for As 1.28 mg kg-1 (p < 0.001) and Pb 0.013 mg kg-1 (p = 0.0496) than Thunnus albacares. No samples surpassed the limits set by the EU for Cd and Pb. The limit for As in fish has not been established, but the arsenic contents in fresh tuna reported here are important, as they are among the highest reported in the literature. Considering public health in children and adults with respect to the investigated metals, the estimated daily intakes (EDIs) did not exceed the tolerable intakes. No chronic systemic risk was found since all the target hazard quotients (THQs-TTHQs) were far below 1 (critical value), and the carcinogenic risk (CR) for As did not exceed the acceptable value of 10-5. Thus, tuna consumption in the Galician diet does not pose a risk for different population groups in terms of these studied metals/metalloids.

Total mercury in fresh and processed tuna marketed in Galicia (NW Spain) in relation to dietary exposure.

Mercury is a toxic trace metal, which can accumulate to levels threatening human and environmental health. In this study, contents of total mercury have been determined by ICP-MS spectrometry in fresh and processed tuna (110 samples) purchased from supermarkets in NW Spain. Mercury was present in all samples analyzed; however, only one sample of fresh tuna (1.070 mg kg-1 wet weight (w.w.)) slightly exceeded the limit of the EU (1.0 mg kg-1 w.w.). The average mercury concentration in processed tuna was lower than fresh, 0.306 mg kg-1 w.w., and ranged from 0.080 to 0.715 mg kg-1 w.w. Results were compared with literature data. In regard to the three types of preparation-packaging media for canned tuna, total Hg content was found in the following order: olive oil > natural > pickled sauce; the last showed significant statistical differences (p < 0.01) with the other two preparations. Between the two evaluated canned tuna species, significant statistical differences (p = 0.008) were observed and Thunnus alalunga presented a greater mean content (0.332 ± 0.114 mg kg-1 w.w.) compared to Thunnus albacares (0.266 ± 0.171 mg kg-1 w.w.).Taking into account the AESAN recommendation for adults and children, as well as the EU regulations and the tuna consumption by the Spanish population, the Hg levels obtained in this study pose no risk to consumer health. However, additional studies, a monitoring process, and efforts to reduce Hg concentration in tuna would be necessary, as well as considering other sources of exposure to Hg.

Cadmium in edible mushrooms from NW Spain: Bioconcentration factors and consumer health implications.

Mushrooms do not constitute a significant portion of the human diet, but the consumption of wild and cultivated mushrooms has become increasingly in recent years. Some species accumulate high levels of toxic metals, both in unpolluted and polluted areas. In this study, we examined the accumulation capacity of cadmium in edible mushrooms in relation to certain factors and their possible toxicological implications. Cadmium concentrations were determined by an ICP-MS spectrometer in 238 samples of the fruiting bodies of 28 wild and cultivated growing edible mushrooms species and the underlying soil. The hymenophore (H) and the rest of the fruiting body (RFB) were analysed separately. The highest mean cadmium concentration (mg/kg dry weight) was found in Agaricus macrosporus (52.9 in H and 28.3 in RFB). All mushroom species accumulated cadmium in relation to the underlying soils. There were statistically significant differences between the hymenophore and the rest of the fruiting body (p < 0.001). Cadmium concentrations were compared to data in the literature and to levels set by legislation. It was concluded that consumption of our studied mushrooms is not a toxicological risk as far as cadmium content is concerned, although the species A. macrosporus should not be consumed.

A compact miniaturized continuous flow system for the determination of urea content in milk.

A multicommutation-based flow system with photometric detection was developed, employing an analytical microsystem constructed with low temperature co-fired ceramics (LTCC) technology, a solid-phase reactor containing particles of Canavalia ensiformis DC (urease source) immobilized with glutaraldehyde, and a mini-photometer coupled directly to the microsystem which monolithically integrates a continuous flow cell. The determination of urea in milk was based on the hydrolysis of urea in the solid-phase reactor and the ammonium ions produced were monitored using the Berthelot reaction. The analytical curve was linear in the urea concentration range from 1.0 x 10(-4) to 5.0 x 10(-3) mol L(-1) with a limit of detection of 8.0 x 10(-6) mol L(-1). The relative standard deviation (RSD) for a 2.0 x 10(-3) mol L(-1) urea solution was lower than 0.4% (n = 10) and the sample throughput was 13 h(-1). To check the reproducibility of the flow system, calibration curves were obtained with freshly prepared solutions on different days and the RSD obtained was 4.7% (n = 6). Accuracy was assessed by comparing the results of the proposed method with those from the official procedure and the data are in close agreement, at a 95% confidence level.

Ceramic microsystem incorporating a microreactor with immobilized biocatalyst for enzymatic spectrophotometric assays.

Low-temperature cofired ceramics (LTCC) technology is a versatile fabrication technique used to construct microflow systems. It permits the integration of several unitary operations (pretreatment, separation, (bio)chemical reaction, and detection stage) of an analytical process in a modular or monolithic way. Moreover, because of its compatibility with biological material, LTCC is adequate for analytical applications based on enzymatic reactions. Here we present the design, construction, and evaluation of a LTCC microfluidic system that integrates a microreactor (internal volume, 24.28 microL) with an immobilized beta-galactosidase from Escherichia coli (0.479 activity units) and an optical flow cell to measure the product of the enzymatic reaction. The enzyme was immobilized on a glyoxal-agarose support, maintaining its activity along the time of the study. As a proof of concept, the LTCC-beta-galactosidase system was tested by measuring the conversion of ortho-nitrophenyl beta-D-galactopyranoside, the substrate usually employed for activity determinations. Once packed in a monolithically integrated microcolumn, the miniaturized flow system was characterized, the operational conditions optimized (flow rate and injection volume), and its performance successfully evaluated by determining the beta-galactosidase substrate concentration at the millimolar level.

Lead in edible mushrooms: levels and bioaccumulation factors.

Lead content was determined in 238 samples of 28 species of edible mushrooms collected from different sites in the province of Lugo (NW Spain) during 2005 and 2006. The hymenophore (H) and the rest of the fruiting body (RFB) were analysed separately. The analyses were carried out by an anodic stripping voltammetric technique using drop mercury as the working electrode. The highest mean lead contents (mg/kg dry weight) of 3.6 and 4.1, 3.0 and 2.2, 2.5 and 2.3, 2.4 and 2.3 were determined in Coprinus comatus, Agaricus campestris, Lepista nuda and Calvatia utriformis in hymenophore and the rest of fruiting bodies, respectively, while the lowest in Agaricus bisporus (0.35 in H and 0.54 in RFB) and Fistulina hepatica (0.41 in H and 0.50 in RFB). All mushroom species were bioexclusors of lead (BCF<1) in relation to the underlying soils. There were not statistically significant differences between lead levels in hymenophore and in the rest of the fruiting bodies. The lead concentrations were compared to literature data and levels set by legislation. It can be concluded that the consumption of these mushrooms can not be considered as a toxicological risk from lead content point of view, and they provide a nutritional requirement to the diet.

Simple modeling of the physical sample dispersion process in rectangular meso (micro) channels with pressure-driven flows.

The present paper reports the modeling and characterization of the physical sample dispersion process observed in rectangular microchannels when pressure-driven pumping is used. To explain experimental results provided by the silicon fluidic device constructed, two different mathematical models were tested. The first one is based on the diffusion-convection model, and the second one is based on the combination of ideal reactors. The silicon designed and constructed chip includes a microfluidic manifold with four inlet-outlet ports and a monolithically integrated optical flow cell. The microchannels, the optical flow cell, and the input-output ports were micromachined on a silicon wafer and then sealed with Pyrex glass anodically bonded. Optical windows were integrated in the chip, allowing simple absorbance-transmission measurements. Pressure-driven flows through fluidic channels were controlled via three-way solenoid valves and provided by an automatic microburette operating in aspiration mode. Experimentally obtained results demonstrate that the physical sample dispersion process can be easily modeled as a combination of a continuous stirred tank reactor and a plug-flow reactor.

Vortex configuration flow cell based on low-temperature cofired ceramics as a compact chemiluminescence microsystem.

The integration of optical detection methods in continuous flow microsystems can highly extend their range of application, as long as some negative effects derived from their scaling down can be minimized. Downsizing affects to a greater extent the sensitivity of systems based on absorbance measurements than the sensitivity of those based on emission ones. However, a careful design of the instrumental setup is needed to maintain the analytical features in both cases. In this work, we present the construction and evaluation of a simple miniaturized optical system, which integrates a novel flow cell configuration to carry out chemiluminescence (CL) measurements using a simple photodiode. It consists of a micromixer based on a vortex structure, which has been constructed by means of the low-temperature cofired ceramics (LTCC) technology. This mixer not only efficiently promotes the CL reaction due to the generated high turbulence but also allows the detection to be carried out in the same area, avoiding intensity signal losses. As a demonstration, a flow injection system has been designed and optimized for the detection of cobalt(II) in water samples. It shows a linear response between 2 and 20 microM with a correlation of r > 0.993, a limit of detection of 1.1 microM, a repeatability of RSD = 12.4%, and an analysis time of 17 s. These results demonstrate the suitability of the proposal to the determination of compounds involved in CL reactions by means of an easily constructed versatile device based on low-cost instrumentation.

Miniaturized total analysis systems: integration of electronics and fluidics using low-temperature co-fired ceramics.

The advantages of microanalyzers, usually fabricated in silicon, glass, or polymers, are well-known. The design and construction of fluidic platforms are well-developed areas due to the perfectly established microfabrication technologies used. However, there is still the need to achieve devices that include not only the fluid management system but also the measurement electronics, so that real portable miniaturized analyzers can be obtained. Low-temperature co-fired ceramics technology permits the incorporation of actuators, such as micropumps and microvalves, controlled either magnetically, piezoelectrically, or thermally. Furthermore, electronic circuits can be also easily built exploiting the properties of these ceramics and the fact that they can be fabricated using a multilayer approach. In this work, taking advantage of the possibility of combining fluidics and electronics in a single substrate and using the same fabrication methodology, a chemical microanalyzer that integrates microfluidics, the detection system, and also the data acquisition and digital signal processing electronics is presented. To demonstrate the versatility of the technology, two alternative setups have been developed. In the first one, a modular configuration is proposed. In this case, the same electronic module can be used to determine different chemical parameters by simply exchanging the chemical module. In the second one, the monolithic integration of all the elements was accomplished, allowing the construction of compact and dedicated devices. Chloride ion microanalyzers have been constructed to demonstrate the operability of both device configurations. In all cases, the results obtained showed adequate analytical features.

Soil calcium and pH monitoring sensor system.

An agrarian sensorial system based on temperature, moisture, and all solid-state ion-selective potentiometric sensors was developed with the objective of monitoring the behavior of H+ and Ca2+ ions in soil and in real conditions, contributing with a new tool that tries to complement the current precision agriculture technology. The evaluation of the sensorial system to pH monitoring presented a good correlation between the results obtained by the system and the standard methodology, allowing us to notice the soil buffer capacity at different soil depths. With regard to calcium, the sensor system also presented an agreement between its results and those obtained by flame atomic absorption spectrometry, using a calibration model based on multiple linear regressions that allows the correct determination of Ca2+ concentrations in soil depths where the relative moisture is different. In this way, using well-known potentiometric sensors in a complex, discontinued, and heterogeneous matrix, such as soil, the sensorial system proved to be a useful task for agrochemical field applications.

Pesticide determination by enzymatic inhibition and amperometric detection in a low-temperature cofired ceramics microsystem.

Among the several fabrication techniques used to construct microflow systems, the low-temperature cofired ceramics (LTCC) technology, taking advantage of its multilayer approach, is one of the most versatile ones. It permits the integration of several unitary operations of an analytical process in a modular or monolithic way. Moreover, due to its perfect compatibility with screen-printing techniques, it also permits the integration of electronic components used to control the whole system setup. In this work the design, construction, and evaluation of a miniaturized analyzer for pesticide determination that integrates a pretreatment stage, based on two mixers or reactors, and an amperometric detection system to measure the product of an enzymatic inhibition reaction are presented. The detection system was monolithically integrated in the microfluidic platform, and it consisted of a screen-printed reference electrode and two platinum sheets, acting as auxiliary and working electrodes, which were embedded within the ceramic structure. The miniaturized system was characterized and successfully evaluated by determining carbofuran at the nanomolar level.

New hexamethine-hemicyanine dyes for the development of integrated optochemical sensors.

New far-visible absorbing anilino-cyanine dyes have been synthesised for future application as chromoionophores in integrated waveguide absorbance optodes based on bulk optodes. The effect of the heterocycle, of the substitution of the heterocyclic nitrogen and of the type of heptamethine central ring on the pKa values (4.3-8.2 in ethanol-water solutions and 9.5-11.0 in plasticised PVC membranes), on the spectroscopic characteristics of the dye and on photostability is discussed. pH-selective bulk optodes have been formulated as a first approach to develop ion-selective optodes, and sensitivity, repeatability, lifetime and response time have been determined. The dyes show good analytical behaviour for use as chromoionophores for the development of ion-selective optodes. Reversible (80-87%), fast (tr90%=0.94-2.28 min) and pH-sensitive membranes (slopes of 0.09-0.23 DeltaAbs.pHdec-1, absorbance range 0.19-0.53) have been obtained. Moreover, they exhibit good spectroscopic features for employment with integrated optochemical sensors: absorption maxima of the acidic species in plasticised PVC membranes matched those of 650-670-nm LEDs, high molar absorption coefficients (epsilonacidic=3.5x10(4)-9.3x10(4) L mol-1 cm-1 and epsilonbasic=1.9x10(4)-6.7x10(4) L mol-1 cm-1) and fluorescence.

Microflow injection system based on a multicommutation technique for nitrite determination in wastewaters.

In this work a microflow structure, suitable for micro-FIA (micro flow injection analysis), will be described, evaluated and applied to real samples. Microchannels, the detector flow cell and input/output ports have been micromachined in silicon and sealed with anodically bonded Pyrex glass. The channels are defined by etching approximately 200 microm depth in silicon using a dry reactive ion etching (RIE) process. Optical windows integrated in the chip structure allow simple absorbance/transmission measurements to be made. The optical measurements were made using an LED as emitter (lambda=525 nm) and a photodiode as a detector. A Visual-Basic program has been developed to control an automatic burette, three-way solenoid valves and the data acquisition system. The micro-FIA for nitrite determination using the Griess-Ilosvay reaction has been implemented for the on-line monitoring of wastewater treatment plants (WWTPs). The multicommutation concept has been applied in order to enhance the mixing process inside the microsystem. Tandem streams of reagent and sample were generated and evaluated at different commutation frequencies. Two optimal frequencies, 400/200 ms and 150/450 ms, were found to be the most suitable ones. The first commutation ratio gave rise to wide linear working range (0-250 ppm), in spite of a high detection limit (0.35 ppm) and a low sensitivity (0.0041+/-0.0004 AU ppm-1). With the second ratio, the working linear range was smaller (0-50 ppm) but the detection limit (0.17 ppm) and the sensitivity (0.0091+/-0.0003 AU ppm-1) improved remarkably. Finally, real samples with a high nitrite concentration (0-1500 ppm) coming from a study of kinetic inhibition in the nitrification process at a WWTP has been analysed with the proposed micro-FIA system. The obtained results have allowed the corroboration of the model of inhibition by the nitrite ion with great exactitude.