Semiconductor Quantum Dots in Chemical Sensors and Biosensors

Quantum dots are nanometre-scale semiconductor crystals with unique optical properties that are advantageous for the development of novel chemical sensors and biosensors. The surface chemistry of luminescent quantum dots has encouraged the development of multiple probes based on linked recognition molecules such as peptides, nucleic acids or small-molecule ligands. This review overviews the design of sensitive and selective nanoprobes, ranging from the type of target molecules to the optical transduction scheme. Representative examples of quantum dot-based optical sensors from this fast-moving field have been selected and are discussed towards the most promising directions for future research

Capillary electrophoretic separation of nanoparticles

In the present work, CdSe nanocrystals (NCs) synthesized with a trioctylphosphine surface passivation layer were modified using amphiphilic molecules to form a surface bilayer capable of providing stable NCs aqueous solutions. Such modified nanocrystals were used as a test solute in order to analyze new electrophoretic phenomena, by applying a micellar plug as a separation tool for discriminating nanocrystals between micellar and micelle-free zones during electrophoresis. The distribution of NCs between both zones depended on the affinity of nanocrystals towards the micellar zone, and this relies on the kind of surface ligands attached to the NCs, as well as electrophoretic conditions applied. In this case, the NCs that migrated within a micellar zone can be focused using a preconcentration mechanism. By modifying electrophoretic conditions, NCs were forced to migrate outside the micellar zone in the form of a typical CZE peak. In this situation, a two-order difference in separation efficiencies, in terms of theoretical plates, was observed between focused NCs (N ~ 107) and a typical CZE peak for NCs (N ~ 105). By applying the amino-functionalized NCs the preconcentration of NCs, using a micellar plug, was examined, with the conclusion that preconcentration efficiency, in terms of the enhancement factor for peak height (SEFheight) can be, at least 20. The distribution effect was applied to separate CdSe/ZnS NCs encapsulated in silica, as well as surface-modified with DNA, which allows the estimation of the yield of conjugation of biologically active molecules to a particle surface

Gene Expression Responses Linked to Reproduction Effect Concentrations (EC10,20,50,90) of Dimethoate, Atrazine and Carbendazim, in Enchytraeus albidus

BACKGROUND: Molecular mechanisms of response to pesticides are scarce and information on such responses from soil invertebrates is almost inexistent. Enchytraeus albidus (Oligochaeta) is a standard soil ecotoxicology model species for which effects of many pesticides are known on survival, reproduction and avoidance behaviour. With the recent microarray development additional information can be retrieved on the molecular effects. METHODOLOGY/PRINCIPAL FINDINGS: Experiments were performed to investigate the transcription responses of E. albidus when exposed to three pesticides - dimethoate (insecticide), atrazine (herbicide) and carbendazim (fungicide) - in a range of concentrations that inhibited reproduction by 10%, 20%, 50% and 90% (EC(10), EC(20), EC(50) and EC(90), respectively). The goal of this study was to further identify key biological processes affected by each compound and if dose-related. All three pesticides significantly affected biological processes like translation, regulation of the cell cycle or general response to stress. Intracellular signalling and microtubule-based movement were affected by dimethoate and carbendazim whereas atrazine affected lipid and steroid metabolism (also by dimethoate) or carbohydrate metabolism (also by carbendazim). Response to DNA damage/DNA repair was exclusively affected by carbendazim. CONCLUSIONS: Changes in gene expression were significantly altered after 2 days of exposure in a dose-related manner. The mechanisms of response were comparable with the ones for mammals, suggesting across species conserved modes of action. The present results indicate the potential of using gene expression in risk assessment and the advantage as early markers

Effects of temperature in juvenile seabass (Dicentrarchus labrax L.) biomarker responses and behaviour: implications for environmental monitoring

The effects of temperature on European seabass (Dicentrarchus labrax L.) juveniles were investigated using a 30-day bioassay carried out at 18 and 25 °C in laboratory conditions. A multiparameter approach was applied including fish swimming velocity and several biochemical parameters involved in important physiological functions. Fish exposed for four weeks to 25 °C showed a decreased swimming capacity, concomitant with increased oxidative stress (increased catalase and glutathione peroxidase activities) and damage (increased lipid peroxidation levels), increased activity of an enzyme involved in energy production through the aerobic pathway (isocitrate dehydrogenase) and increased activities of brain and muscle cholinesterases (neurotransmission) compared to fish kept at 18 °C. Globally, these findings indicate that basic functions, essential for juvenile seabass surviving and well performing in the wild, such as predation, predator avoidance, neurofunction and ability to face chemical stress may be compromised with increasing water temperature. This may be of particular concern if D. labrax recruitment phase in northwest European estuaries and coastal areas happens gradually inmore warm environments as a consequence of global warming. Considering that the selected endpoints are generally applied in monitoring studies with different species, these findings also highlight the need of more research, including interdisciplinary and multiparameter approaches, on the impacts of temperature on marine species, and stress the importance of considering scenarios of temperature increase in environmental monitoring and in marine ecological risk assessment

Cost-effectiveness of minimally invasive sacroiliac joint fusion

Daniel J Cher,1 Melissa A Frasco,2 Ren&eacute;e JG Arnold,2,3 David W Polly4,5 1Clinical Affairs, SI-BONE, Inc., San Jose, CA, USA; 2Division of Health Economics and Outcomes Research, Quorum Consulting, Inc., San Francisco, CA, USA; 3Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA; 4Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN, USA; 5Department of Neurosurgery, University of Minnesota, Minneapolis, MN, USA Background: Sacroiliac joint (SIJ) disorders are common in patients with chronic lower back pain. Minimally invasive surgical options have been shown to be effective for the treatment of chronic SIJ dysfunction. Objective: To determine the cost-effectiveness of minimally invasive SIJ fusion. Methods: Data from two prospective, multicenter, clinical trials were used to inform a Markov process cost-utility model to evaluate cumulative 5-year health quality and costs after minimally invasive SIJ fusion using triangular titanium implants or non-surgical treatment. The analysis was performed from a third-party perspective. The model specifically incorporated variation in resource utilization observed in the randomized trial. Multiple one-way and probabilistic sensitivity analyses were performed. Results: SIJ fusion was associated with a gain of approximately 0.74 quality-adjusted life years (QALYs) at a cost of US13,313 per QALY gained. In multiple one-way sensitivity analyses all scenarios resulted in an incremental cost-effectiveness ratio (ICER) <26,000/QALY. Probabilistic analyses showed a high degree of certainty that the maximum ICER for SIJ fusion was less than commonly selected thresholds for acceptability (mean ICER =$13,687, 95$5,162&ndash;$28,085). SIJ fusion provided potential cost savings per QALY gained compared to non-surgical treatment after a treatment horizon of greater than 13 years. Conclusion: Compared to traditional non-surgical treatments, SIJ fusion is a cost-effective, and, in the long term, cost-saving strategy for the treatment of SIJ dysfunction due to degenerative sacroiliitis or SIJ disruption. Keywords: cost-effectiveness analysis, degenerative sacroiliitis, minimally invasive surgery, sacroiliac joint arthrodesis, sacroiliac joint disruptions, sacroiliac joint dysfunction, spine surger

Cost-effectiveness of minimally invasive sacroiliac joint fusion [Corrigendum]

Cher DJ, Frasco MA, Arnold RJ, Polly DW. Clinicoecon Outcomes Res. 2016;8:1&ndash;14.Daniel J Cher is an SI-BONE employee. Renee JG Arnold and Melissa A Frasco are employees of Quorum Consulting, hired by SI-BONE to help prepare and evaluate the cost-utility model. David Polly is an investigator in clinical research studies sponsored by SI-BONE but has no financial interest in the company. The authors report no other conflicts of interest in this work.View original article by Cher et al

Modos de leer y escribir, estrategias de apropiación de la alfabetización académica de los estudiantes de primer año de la Licenciatura en Nutrición de la Universidad Nacional de La Matanza.

El proceso de democratización del acceso a la educación superior tuvo, entre otros efectos, el aumento de la expansión de la matrícula del sector y la ampliación y diversificación de la oferta institucional. A su vez, dicho proceso encontró su límite en la posibilidad de retener a los/as alumnos/as y expandir la tasa de graduación, volviendo no sólo al acceso sino también a la permanencia en la universidad un problema social. En este marco, nos interesa específicamente analizar un aspecto de la permanencia que se vincula con el desencuentro entre lo esperado por los profesores y lo que los estudiantes logran en sus experiencias de lectura y escritura académica, así como, a la preocupación por las consecuencias de este desacople en torno a la trayectoria y la permanencia de los estudiantes en la universidad. Para ello, en este artículo presentamos los resultados de una investigación cuyo objetivo fue indagar sobre modos de leer, escribir y estrategias de apropiación de alfabetización académica de estudiantes de primer año de la Licenciatura en Nutrición de una universidad del conurbano bonaerense. Se trató de un estudio que combinó diversas técnicas: entrevistas en profundidad, observación de clases y un cuestionario autoadministrado a estudiantes. Entre los resultados principales se destacan las grandes dificultades que los estudiantes encuentran relacionadas con la organización del tiempo y de la carga de lectura. Así como, también, los relatos autoculpabilizadores e individualizantes que componen en torno a la imposibilidad de construir una trayectoria académica que respete los tiempos institucionales propuestos. Partiendo de estos hallazgos, buscamos contribuir al diseño de acciones que posibiliten a los docentes mejorar los procesos de enseñanza y aprendizaje de la lectura y la escritura en el nivel superior