The Spanish E-retailing Customers Segmentation

This article analyses different factors that influence the purchasing behaviour of online supermarket customers. These factors are related to both the appearance of the website as well as the processes that take place when making the purchase. Based on these analyses, the various groups of consumers with homogenous behaviour are studied. The analysis also allows the quality of the service offered by this kind of establishment to be defined, as well as the main dimensions in which it develops. In the conclusions, factors which should influence the manager of an online supermarket to improve the quality of its service are given.Virtual supermarket; segmentation; Internet; E-commerce; marketing.

Validation of a Phase-Mass Characterization Concept and Interface for Acoustic Biosensors

Acoustic wave resonator techniques are widely used in in-liquid biochemical applications. The main challenges remaining are the improvement of sensitivity and limit of detection, as well as multianalysis capabilities and reliability. The sensitivity improvement issue has been addressed by increasing the sensor frequency, using different techniques such as high fundamental frequency quartz crystal microbalances (QCMs), surface generated acoustic waves (SGAWs) and film bulk acoustic resonators (FBARs). However, this sensitivity improvement has not been completely matched in terms of limit of detection. The decrease on frequency stability due to the increase of the phase noise, particularly in oscillators, has made it impossible to increase the resolution. A new concept of sensor characterization at constant frequency has been recently proposed based on the phase/mass sensitivity equation: Δφ/Δm ≈ −1/mL, where mL is the liquid mass perturbed by the resonator. The validation of the new concept is presented in this article. An immunosensor application for the detection of a low molecular weight pollutant, the insecticide carbaryl, has been chosen as a validation model

A High Fundamental Frequency (HFF)-based QCM Immunosensor for Tuberculosis Detection

Tuberculosis, one of the oldest diseases affecting human beings, is still considered as a world public health problem by the World Health Organization. Therefore, there is a need for new and more powerful analytical methods for early illness diagnosis. With this idea in mind, the development of a High Fundamental Frequency (HFF) piezoelectric immunosensor for the sensitive detection of tuberculosis was undertaken. A 38 kDa protein secreted by Mycobacterium tuberculosis was first selected as the target biomarker. Then, specific monoclonal antibodies (MAbs) were obtained. Myc-31 MAb, which showed the highest affinity to the analyte, was employed to set up a reference enzyme-linked immunosorbent assay (ELISA) with a limit of detection of 14 ng mL-1 of 38 kDa antigen. For the development of the HFF piezoelectric immunosensor, 100 MHz quartz crystals were used as transducer elements. The gold electrode surface was functionalized by covalent immobilization of the target biomarker through mixed self-assembled monolayers (mSAM) of carboxylic alkane thiols. A competitive immunoassay based on Myc-31 MAb was integrated with the transducer as sensing bio-recognition event. Reliable assay signals were obtained using low concentrations of antigen for functionalization and MAb for the competitive immunoassay. Under optimized conditions, the HFF immunosensor calibration curve for 38 kDa determination showed a limit of detection as low as 11 ng mL-1 of the biomarker. The high detectability attained by this immunosensor, in the picomolar range, makes it a promising tool for the easy, direct and sensitive detection of the tuberculosis biomarker in biological fluids such as sputum.This study was supported by COLCIENCIAS (Colombia), Project no. 13335212865) and by AWSensors (Valencia, Spain). All of the authors: A. Montoya, C. March, Y.J. Montagut, M.J. Moreno, J.J. Manclus, A. Arnau, Y. Jimenez, M. Jaramillo, P. A. Marin and R.A. Torres declare that they have no conflict of interest.Montoya Baides, Á.; March Iborra, MDC.; Montagut Ferizzola, YJ.; Moreno Tamarit, MJ.; Manclus Ciscar, JJ.; Arnau Vives, A.; Jiménez Jiménez, Y.... (2017). A High Fundamental Frequency (HFF)-based QCM Immunosensor for Tuberculosis Detection. Current Topics in Medicinal Chemistry. 17(14):1623-1630. https://doi.org/10.2174/1568026617666161104105210S16231630171

Love Wave Immunosensor for the Detection of Carbaryl Pesticide

A Love Wave (LW) immunosensor was developed for the detection of carbaryl pesticide. The experimental setup consisted on: a compact electronic characterization circuit based on phase and amplitude detection at constant frequency; an automated flow injection system; a thermal control unit; a custom-made flow-through cell; and Quartz /SiO2 LW sensors with a 40 μm wavelength and 120 MHz center frequency. The carbaryl detection was based on a competitive immunoassay format using LIB-CNH45 monoclonal antibody (MAb). Bovine Serum Albumin-CNH (BSA-CNH) carbaryl hapten-conjugate was covalently immobilized, via mercaptohexadecanoic acid self-assembled monolayer (SAM), onto the gold sensing area of the LW sensors. This immobilization allowed the reusability of the sensor for at least 70 assays without significant signal losses. The LW immunosensor showed a limit of detection (LOD) of 0.09 μg/L, a sensitivity of 0.31 μg/L and a linear working range of 0.14–1.63 μg/L. In comparison to other carbaryl immunosensors, the LW immunosensor achieved a high sensitivity and a low LOD. These features turn the LW immunosensor into a promising tool for applications that demand a high resolution, such as for the detection of pesticides in drinking water at European regulatory levels.The author also would like to acknowledge the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ERDF) for their financing support through the grant of the INNPACTO 2012 project (DETECTA IPT-2012-0154-300000), J.V. Garcia's Fellowship, AP2007-03745, of FPU (Formacion de Profesorado Universitario) program, M. I. Rocha-Gaso's PhD CONACyT Fellowship and AWSensors Inc. for its collaboration.Rocha-Gaso, M.; García Narbón, JV.; García, P.; March Iborra, MDC.; Jiménez Jiménez, Y.; Francis, L.; Montoya Baides, Á.... (2014). Love Wave Immunosensor for the Detection of Carbaryl Pesticide. Sensors. 14(9):16434-16453. https://doi.org/10.3390/s140916434S1643416453149March, C., Manclús, J. J., Jiménez, Y., Arnau, A., & Montoya, A. (2009). A piezoelectric immunosensor for the determination of pesticide residues and metabolites in fruit juices. Talanta, 78(3), 827-833. doi:10.1016/j.talanta.2008.12.058Janshoff, A., Galla, H.-J., & Steinem, C. (2000). Piezoelectric Mass-Sensing Devices as Biosensors—An Alternative to Optical Biosensors? Angewandte Chemie, 39(22), 4004-4032. doi:10.1002/1521-3773(20001117)39:223.0.co;2-2Rocha-Gaso, M.-I., March-Iborra, C., Montoya-Baides, Á., & Arnau-Vives, A. (2009). Surface Generated Acoustic Wave Biosensors for the Detection of Pathogens: A Review. Sensors, 9(7), 5740-5769. doi:10.3390/s90705740Gronewold, T. M. A. (2007). Surface acoustic wave sensors in the bioanalytical field: Recent trends and challenges. Analytica Chimica Acta, 603(2), 119-128. doi:10.1016/j.aca.2007.09.056Länge, K., Rapp, B. E., & Rapp, M. (2008). Surface acoustic wave biosensors: a review. Analytical and Bioanalytical Chemistry, 391(5), 1509-1519. doi:10.1007/s00216-008-1911-5Arnau, A., Montagut, Y., García, J. V., & Jiménez, Y. (2009). A different point of view on the sensitivity of quartz crystal microbalance sensors. Measurement Science and Technology, 20(12), 124004. doi:10.1088/0957-0233/20/12/124004Montagut, Y. J., García, J. V., Jiménez, Y., March, C., Montoya, A., & Arnau, A. (2011). Frequency-shift vs phase-shift characterization of in-liquid quartz crystal microbalance applications. Review of Scientific Instruments, 82(6), 064702. doi:10.1063/1.3598340Abad, A., Primo, J., & Montoya, A. (1997). Development of an Enzyme-Linked Immunosorbent Assay to Carbaryl. 1. Antibody Production from Several Haptens and Characterization in Different Immunoassay Formats. Journal of Agricultural and Food Chemistry, 45(4), 1486-1494. doi:10.1021/jf9506904Manclús, J. J., Abad, A., Lebedev, M. Y., Mojarrad, F., Micková, B., Mercader, J. V., … Montoya, A. (2004). Development of a Monoclonal Immunoassay Selective for Chlorinated Cyclodiene Insecticides. Journal of Agricultural and Food Chemistry, 52(10), 2776-2784. doi:10.1021/jf035382hFrancis, L. A., Friedt, J.-M., Zhou, C., & Bertrand, P. (2006). In Situ Evaluation of Density, Viscosity, and Thickness of Adsorbed Soft Layers by Combined Surface Acoustic Wave and Surface Plasmon Resonance. Analytical Chemistry, 78(12), 4200-4209. doi:10.1021/ac051233hMauriz, E., Calle, A., Abad, A., Montoya, A., Hildebrandt, A., Barceló, D., & Lechuga, L. M. (2006). Determination of carbaryl in natural water samples by a surface plasmon resonance flow-through immunosensor. Biosensors and Bioelectronics, 21(11), 2129-2136. doi:10.1016/j.bios.2005.10.013Abad, A., & Montoya, A. (1997). Development of an Enzyme-Linked Immunosorbent Assay to Carbaryl. 2. Assay Optimization and Application to the Analysis of Water Samples. Journal of Agricultural and Food Chemistry, 45(4), 1495-1501. doi:10.1021/jf950691wMontagut, Y., García, J. V., Jiménez, Y., March, C., Montoya, Á., & Arnau, A. (2011). Validation of a Phase-Mass Characterization Concept and Interface for Acoustic Biosensors. Sensors, 11(5), 4702-4720. doi:10.3390/s11050470

High-frequency phase shift measurement greatly enhances the sensitivity of QCM immunosensors

[EN] In spite of being widely used for in liquid biosensing applications, sensitivity improvement of conventional (5-20 MHz) quartz crystal microbalance (QCM) sensors remains an unsolved challenging task. With the help of a new electronic characterization approach based on phase change measurements at a constant fixed frequency, a highly sensitive and versatile high fundamental frequency (HFF) QCM immunosensor has successfully been developed and tested for its use in pesticide (carbaryl and thiabendazole) analysis. The analytical performance of several immunosensors was compared in competitive immunoassays taking carbaryl insecticide as the model analyte. The highest sensitivity was exhibited by the 100 MHz HFF-QCM carbaryl immunosensor. When results were compared with those reported for 9 MHz QCM, analytical parameters clearly showed an improvement of one order of magnitude for sensitivity (estimated as the I50 value) and two orders of magnitude for the limit of detection (LOD): 30 µg L-1 vs 0.66 µg L-1 I50 value and 11 µg L-1 vs 0.14 µg L-1 LOD, for 9 and 100 MHz, respectively. For the fungicide thiabendazole, I50 value was roughly the same as that previously reported for SPR under the same biochemical conditions, whereas LOD improved by a factor of 2. The analytical performance achieved by high frequency QCM immunosensors surpassed those of conventional QCM and SPR, closely approaching the most sensitive ELISAs. The developed 100 MHz QCM immunosensor strongly improves sensitivity in biosensing, and therefore can be considered as a very promising new analytical tool for in liquid applications where highly sensitive detection is required.We would like to acknowledge Federico Martin and Juan Antonio Buitrago for their excellent technical assistance. This work was supported by the Spanish Ministry of Economy and Competitiveness/European Regional Development Fund (ERDF) (DETECTA IPT-2012-0154-300000 project).March Iborra, MDC.; García Narbón, JV.; Sánchez, Á.; Arnau Vives, A.; Jiménez Jiménez, Y.; García, P.; Manclus Ciscar, JJ.... (2015). High-frequency phase shift measurement greatly enhances the sensitivity of QCM immunosensors. Biosensors and Bioelectronics. (65):1-8. https://doi.org/10.1016/j.bios.2014.10.001S186

Oscillator for Biosensors based on Quartz Crystal Microbalance (QCM)

[EN] Quartz crystal is generally used in some applications as a microbalance taking advantage of its capacity to change the resonance frequency according to any surface mass change on the resonator.In this way a quartz crystal can be used as a transducer in a piezoelectric inmunosensor system in order to detect antigen-antibody bonds. An interface for Quartz Crystal Microbalances, QCM, based on an improved version of an oscillator in balanced differential configuration and its respective validation as a biosensor characterization system is introduced in this paper. The system was successfully tested in a piezoelectric inmunosensor for detecting the pesticide Carbaryl.[ES] El cristal de cuarzo generalmente es usado en aplicaciones como microbalanza, aprovechando la capacidad que presenta éste para variar su frecuencia de resonancia de acuerdo a los cambios de la densidad superficial de masa depositada en la superficie del resonador. De esta manera, un cristal de cuarzo puede ser utilizado como transductor en un sistema de inmunosensor piezoeléctrico, para detectar uniones antígeno – anticuerpo. En este artículo se presenta una interfaz para microbalanzasde cristal de cuarzo, QCM (del inglés Quartz Crystal Microbalance) basado en una versión mejorada de oscilador en configuración diferencial equilibrado y su validación como sistema de caracterización para biosensores. El sistema fue probado con éxito en un inmunosensor piezoeléctrico para la detección del plaguicida Carbaryl.Montagut Ferizzola, YJ.; García Narbón, JV.; Jiménez Jiménez, Y.; March Iborra, MDC.; Montoya Baides, Á.; Torres Villa, RA.; Arnau Vives, A. (2011). Oscilador para biosensores basado en microbalanza de cristal de cuarzo (QCM). Facultad de Ingeniería. Universidad de Antioquia. 61:160-168. http://hdl.handle.net/10251/55018S1601686

P53 wild-type colorectal cancer cells that express a fetal gene signature are associated with metastasis and poor prognosis

Current therapy against colorectal cancer (CRC) is based on DNA-damaging agents that remain ineffective in a proportion of patients. Whether and how non-curative DNA damage-based treatment affects tumor cell behavior and patient outcome is primarily unstudied. Using CRC patient-derived organoids (PDO)s, we show that sublethal doses of chemotherapy (CT) does not select previously resistant tumor populations but induces a quiescent state specifically to TP53 wildtype (WT) cancer cells, which is linked to the acquisition of a YAP1-dependent fetal phenotype. Cells displaying this phenotype exhibit high tumor-initiating and metastatic activity. Nuclear YAP1 and fetal traits are present in a proportion of tumors at diagnosis and predict poor prognosis in patients carrying TP53 WT CRC tumors. We provide data indicating the higher efficacy of CT together with YAP1 inhibitors for eradication of therapy resistant TP53 WT cancer cells. Together these results identify fetal conversion as a useful biomarker for patient prognosis and therapy prescription. The failure of chemotherapy in colorectal cancer is currently unclear. Here, the authors show that upon sub-lethal dose of chemotherapy wild-type p53 colorectal cancers acquire a quiescence-like phenotype and a YAP-dependent fetal-like intestinal stem cell state associated with a higher metastatic activity and poor prognosis in patients

Derecho, género e igualdad : cambios en las estructuras jurídicas androcéntricas. Vol 2

Este libro es producto de una selección de ponencias y comunicaciones presentadas en el "I Congreso Internacional Derecho, Género e Igualdad", organizado por el Grupo Antígona de la Universidad Autónoma de Barcelona durante el año 2009

La gestión de las cooperativas agrarias: tipificación de las cooperativas del sector oleico de Cataluña

El següent treball té com a objectiu mostrar la situació de la gestió en el sector de les cooperatives d'oli a Cataluny