Detection, quantification, and characterization of polystyrene microplastics and adsorbed bisphenol A contaminant using electroanalytical techniques

The potential applications of electroanalytical techniques for the quantification and size characterization of nonelectroactive polystyrene microplastics is reported, in addition to characterizing the kinetics of adsorption of bisphenol A on these polystyrene microparticles. The individual adsorption events of very diluted polystyrene microparticles dispersions on glassy-carbon microelectrodes produce the blocking of the charge transfer of a mediator (ferrocene-methanol) thus decreasing the current of the recorded chronoamperogram in a stepwise manner. The magnitude of the current steps are in the order of pA values and can be related to the diameter of the plastic microparticles in the size range 0.1 to 10 µm. The frequency of the current steps in the domain time used (120 s) allows to quantify the number concentration of these microparticles in the range 0.005 to 0.500 pM. Electrochemical impedance spectroscopy confirms the adsorption of the polystyrene microplastics on carbon microelectrodes (and to a lesser extent on platinum microelectrodes) under the same experimental conditions as above. On the other hand, the adsorbed microplastics become concentrators of other pollutants found in the environment. The sensitive differential-pulse voltammetry determination of bisphenol A (linear range 0.80–15.00 µM; detection limit 0.24 µM) was used together with a simple separation procedure for studying the adsorption of bisphenol A on polystyrene microparticles. The adsorption capacity (mg of bisphenol A retained per g of the polystyrene microplastics) decreased from approximately 5.7 to 0.8 mg g−1 with increasing dosages of polystyrene microparticles from 0.2 to 1.6 g l−1. The adsorption isotherms were modeled resulting in a monolayer of bisphenol A adsorbed on the microplastics (i.e., best fitted to a Langmuir model)

Single-site port robotic-assisted simple nephrectomy (LESS)

Indexación: Web of Science; ScieloIntroduction: Minimally invasive surgery in urology is rapidly advancing and Laparo-endoscopic single-site surgery (LESS) is not the exception. Such laparoscopic procedures are technically challenging and require an experienced laparoscopic surgeon due to the lack of port placement triangulation and instrument clashing. The benefit of the da Vinci surgical system has recently introduced to LESS. We present two cases of robotic LESS nephrectomy. Matherials and Methods: Two patients, a female of 23 years old, diagnosed with right renal atrophy secondary to chronic pyelonephritis and one male patient with diagnosis of left staghorn calculi and renal atrophy. Both underwent to a total nephrectomy assisted by the da Vinci S surgical system through a single port incision using the GelPoint® access system. Results: The first surgery was performed without incidents or conversion. The second patient required the installation of an additional robotic port for triangulation. The dock time and the mean operative time was 18 and 110 min. The mean estimated blood loss was 100 cc and the hospital stay was 27 hours. There were no complications. Conclusions: LESS robotic surgery is feasible using current robotic systems. However, there are several limitations. The design of specific technology for the use of the robot through single incision can solve this problem.Introducción: La cirugía mínimamente invasiva en urología avanza rápidamente y la cirugía laparo-endoscópica a través de puerto único (LESS) no es la excepción. Esta técnica por vía laparoscópica presenta mucha dificultad y requiere de un cirujano laparoscópico experimentado debido a la falta de triangulación y el cruce de los instrumentos. Los beneficios del sistema quirúrgico da Vinci® han sido introducidos recientemente en LESS. Presentamos dos casos de nefrectomía LESS asistida por robot. Materiales y Métodos: Dos pacientes, la primera de sexo femenino y 23 años de edad, con diagnóstico de atrofia renal secundaria a pielonefritis crónica derecha y un segundo paciente de sexo masculino con diagnóstico de litiasis coraliforme izquierda y atrofia renal. Ambos pacientes fueron sometidos a una nefrectomía total asistida por el sistema quirúrgico robótico da Vinci S a través de un puerto único utilizando el dispositivo de acceso GelPoint®. Resultados: La primera cirugía fue llevada a cabo sin incidentes, sin necesidad de conversión. En el segundo paciente fue necesaria la instalación de un puerto robótico adicional para triangulación. El tiempo de acoplamiento y operatorio promedio fue de 18 y 110 min. El sangrado promedio estimado fue de 100 cc y la estadía hospitalaria promedio de 27 horas. No hubo complicaciones. Conclusiones: La cirugía robótica LESS es posible de realizar utilizando los sistemas robóticos actuales. Sin embargo, existen diversas limitaciones. El diseño de tecnología específica para el uso del robot por puerto único podrá solucionar este problema.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-40262011000500011&nrm=is

Virtual intelligent sensors on wide plant control applications: an approach

[Abstract] This paper describes a simple and reliable method to acquire information instantaneously on the basis of predictive computations of data acquired with significant time delay. The estimated value of any measured variable is the output of a virtual sensor implemented by means of a virtual engineering programming too

Preliminary design study to implement multipurpose virtual sensors

[Abstract] This paper describes a method to perform the task of measuring some different magnitudes with a unique differential pressure transducer. To do so, it is necessary to perform the task of calibrate the primary elements of transducers by computing the acquired data with significant non linearities and time varying parameters mainly in the primary element of transducers. The estimated value of any measured variable is the output of a virtual sensor implemented by means of a virtual engineering programming too

Cirugía percutánea de la litiasis renal en la era de la litotripsia extracorpórea: Experiencia en 301 pacientes

Indexación: ScieloIntroduction: Percutaneous renal surgery was introduced more than 20 years ago in urological practice. Extracorporeal Shock Wave Lithotripsy (ESWL) enter the urological scene shortly after. Our objective is to show our experience in percutaneous renal surgery after the introduction of the ESWL in our institution. Material and Methods: Surgical outcomes of 301 patients who underwent percutaneous renal surgery as treatment of renal stones were analyzed. This series begins just before the introduction of ESWL in our unit. Results: Renal pelvis was the most frequent localization with 142 cases (47.2%). There were 51 patients with straghorn calculi. 255 (84.7%) were stone free after one single procedure. Residual fragments were managed with many methods, until only 16 patients (5.4%) had residual fragments. Complications occurred in 26 patients (8.9%). There was no mortality. Conclusions: Percutaneous surgery is an important tool in the management of renal stones. In general, renal stones managed with this procedure, are more complex, however the achievement of good results is possible.La cirugía percutánea (CP) de la litiasis renal fue introducida en la urología hace más de 20 años. Poco después lo hizo la litotripsia extracorpórea (LEC). Nuestro objetivo es mostrar la experiencia en CP luego de la introducción de la LEC en nuestro servicio. Material y Métodos: Se analizan en forma retrospectiva los resultados de 301 pacientes operados por CP por litiasis renal. La serie comienza con la adquisición de un litotriptor extracorpóreo en nuestro servicio. Resultados: La localización más frecuente fue la pelvis renal con 142 casos (47,2%). Se observó litiasis coraliforme en 51 pacientes. Doscientos cincuenta y cinco (84,7%), quedaron libres de litiasis con un procedimiento. La litiasis residual fue tratada con diversos métodos, para un total final de 16 pacientes con fragmentos residuales (5,4%). Ocurrieron complicaciones en 26 pacientes (8,9%). No hubo mortalidad. Conclusiones: La cirugía percutánea de la litiasis renal es un procedimiento que debe formar parte importante en la resolución de la litiasis renal. En general las litiasis tratadas son más complejas, sin embargo, los resultados son excelentes.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-40262010000500013&nrm=is

Nefrectomía simple laparoscópica NOTES y LESS con el uso de instrumentos laparoscópicos estándar: Experiencia inicial en 3 casos

Indexación: ScieloIntroduction: Natural orifice transluminal endoscopic surgery (NOTES) and Laparoendoscopic Single Site Surgery (LESS) are emerging technologies, which allows to performed surgical procedures avoiding any surgical scars. However there are some problems due to the lack of equipment available for these procedures. The aim of these study is to present our initial experience with the transvaginal nephrectomy NOTES and LESS using standard laparoscopic instruments. Material and Methods: Two female patients (23 and 26 years old) with diagnosis of recurrent urinary tract infection and renal atrophy. A laparoscopic simple nephrectomy with transvaginal NOTES assistance was performed, using one access port for the camera and two abdominal work ports of 10 and 3mm. In a third patient (15 years old) a transumbilical LESS nephrectomy was preformed with the use of standard laparoscopic instruments. Results: Average operative time was 110 min (40-200), with an estimated blood loss of 200 cc. There were no perioperative complications and all patients were discharged 36 hours after surgery. Conclusion: Laparoscopic simple nephrectomy with transvaginal NOTES assistance and LESS are technically feasible with the use of standard laparoscopic instruments. Special access trocars and instruments development for this procedure will allow to performed a pure technique without the use of abdominal incisions.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-40262010000300016&nrm=is

Towards on line monitoring the evolution of the myocardium infarction scar with an implantable electrical impedance spectrum monitoring system.

The human heart tissue has a limited capacity for regeneration. Tissue and cellular therapies based on the use of stem cells may be useful alternatives to limit the size of myocardial infarction. In this paper, the preliminary results from an experimental campaign for on-line monitoring of myocardium scar infarction are presented. This study has been carried out under a research project that has as main objective the development and application of a bioactive patch implant for regeneration of myocardial infarction. Electrical Impedance Spectroscopy (EIS) has been chosen as a tissue state monitoring technique. What is presented in this communication is the first results of an implantable EIS measurement system which has been implanted in a subset of the animals corresponding to the control group, along one month. In all the animals, the myocardial infarction was induced by the ligation of the first circumflex marginal artery. In the animal group presented,the bioactive patch scaffold and the electrodes were implanted without the stem cells load. The scaffold is a piece of decellularized human pericardium, lyophilized and rehydrated with hydrogel RAD16-I. Nanogold particles were also placed near the electrodes to improve the electrode area conductivity. The results presented correspond to the subset of animals (n = 5), which had implanted the bioimpedance system monitoring the electrical impedance spectrum in vivo during 1 month. Two electrodes were connected to the bioactive patch implant. A total of 14 logarithmically spaced frequencies were measured every 5 minutes, from 100 Hz to 200 kHz. Results show a convergence of low-frequency and high frequency impedance magnitudes along the measurement period, which is coherent with the scar formation.Postprint (published version