ABSTRACT
In this Letter, we show 3D steady-state trapping and manipulation of vapor bubbles in liquids employing a low-power continuous-wave laser using the Marangoni effect. Light absorption from photodeposited silver nanoparticles on the distal end of a multi-mode optical fiber is used to produce bubbles of different diameters. The thermal effects produced by either the nanoparticles on the fiber tip or the light bulk absorption modulate the surface tension of the bubble wall and creates both longitudinal and transversal forces just like optical forces, effectively creating a 3D potential well. Using numerical simulations, we obtain expressions for the temperature profiles and present analytical expressions for the Marangoni force. In addition, using an array of three fibers with photodeposited nanoparticles is used to demonstrate the transfer of bubbles from one fiber to another by sequentially switching on and off the lasers.
ABSTRACT
The most common approach to optically generate and manipulate bubbles in liquids involves temperature gradients induced by CW lasers. In this work, we present a method to accomplish both the generation of microbubbles and their 3D manipulation in ethanol through optothermal forces. These forces are triggered by light absorption from a nanosecond pulsed laser (λ = 532 nm) at silver nanoparticles photodeposited at the distal end of a multimode optical fiber. Light absorbed from each laser pulse quickly heats up the silver-ethanol interface beyond the ethanol critical-point (â¼ 243 °C) before the heat diffuses through the liquid. Therefore, the liquid achieves a metastable state and owing to spontaneous nucleation converted to a vapor bubble attached to the optical fiber. The bubble grows with semi-spherical shape producing a counterjet in the final stage of the collapse. This jet reaches the hot nanoparticles vaporizing almost immediately and ejecting a microbubble. This microbubble-generation mechanism takes place with every laser pulse (10 kHz repetition rate) leading to the generation of a microbubbles stream. The microbubbles' velocities decrease as they move away from the optical fiber and eventually coalesce forming a larger bubble. The larger bubble is attracted to the optical fiber by the Marangoni force once it reaches a critical size while being continuously fed with each bubble of the microbubbles stream. The balance of the optothermal forces owing to the laser-pulse drives the 3D manipulation of the main bubble. A complete characterization of the trapping conditions is provided in this paper.
ABSTRACT
OBJECTIVE: To describe abnormalities in coagulation and fibrinolysis in septic shock with purpura and to assess the relationship between plasma plasminogen activator inhibitor-1 (PAI-1) concentrations and multiple organ system failure (MOSF). METHODS: Observational study in the pediatric intensive care unit of a tertiary care hospital. The presence of early MOSF was assessed at admission in 15 children with septic shock and purpura consecutively admitted to the pediatric intensive care unit. Blood samples were taken to determine coagulation and fibrinolysis parameters. RESULTS: At admission, MOSF was diagnosed in 7 patients (46.7 %), acute respiratory distress syndrome (ARDS) in 6 (40 %), consumption coagulopathy in 7 (46.7 %) and acute renal failure in 1 (6.7 %). The overall mortality rate was 40 %. Coagulation parameters were generally affected but statistically significant differences were found only in concentrations of fibrinogen and antithrombin III, which were lower in patients with MOSF than in those without organ dysfunction. Fibrinolysis parameters were increased in all patients but plasma PAI-1 concentrations were significantly elevated only in patients with MOSF and in those with ARDS. CONCLUSION: These data indicate that impaired fibrinolysis could play a major role in the development of MOSF in children with septic shock and purpura.
Subject(s)
Blood Coagulation , Multiple Organ Failure/etiology , Purpura/etiology , Shock, Septic/complications , Child , Child, Preschool , Female , Fibrinolysis , Humans , Infant , Male , Multiple Organ Failure/blood , Plasminogen Activator Inhibitor 1/blood , Purpura/blood , Shock, Septic/bloodABSTRACT
Objetivos: Describir las alteraciones en el sistema de la coagulación y la fibrinólisis en el shock séptico asociado a púrpura y analizar la relación entre concentración plasmática de inhibidor del activador del plasminógeno tipo 1 (PAI-1) y la presencia de fracaso multiorgánico (FMO). Métodos: Estudio observacional en la Unidad de Cuidados Intensivos Pediátricos (UCIP) de un hospital universitario de tercer nivel. Se analizó en 15 niños ingresados de forma consecutiva con shock séptico y púrpura la presencia de FMO en el momento del ingreso. Se obtuvieron muestras sanguíneas para estudiar los parámetros del sistema de coagulación y la fibrinólisis. Resultados: En el momento del ingreso 7 pacientes (46,7%) presentaban FMO; 6 pacientes (40%), síndrome de distrés respiratorio agudo (SDRA); 7 pacientes (46,7%), coagulopatía de consumo, y 1 paciente (6,7%), fracaso renal agudo. La mortalidad observada fue de 40%. Los parámetros del sistema de la coagulación analizados estaban en general alterados, aunque sólo se observaron diferencias estadísticamente significativas en las concentraciones plasmáticas de fibrinógeno y antitrombina III que fueron menores en el grupo con FMO que en los pacientes sin disfunción de órganos. Los parámetros de la fibrinólisis estaban aumentados en todos los pacientes pero sólo se observaron concentraciones plasmáticas de PAI-1 significativamente elevadas en el grupo con FMO y en aquellos con SDRA. Conclusiones: Los resultados sugieren que las alteraciones del sistema fibrinolítico pueden tener un papel importante en el desarrollo de FMO en niños con shock séptico y púrpura (AU)
Subject(s)
Child , Child, Preschool , Male , Infant , Female , Humans , Blood Coagulation , Shock, Septic , Plasminogen Activator Inhibitor 1 , Multiple Organ Failure , Purpura , FibrinolysisSubject(s)
Birth Rate , Illegitimacy/history , Marriage/history , Fertility , France , History, 20th CenturyABSTRACT
Recent fertility trends in Spain are analyzed using data from official sources. The author notes that "changes in sexual behavior among the young during the 1970s have given rise to a considerable increase in the number of births conceived [outside of] marriage. However, in the majority of cases, marriage took place before the actual birth. Between 1970 and 1980, the proportion of women pregnant at moment of marriage grew from 10% to 21%. Those changes are similar to those which occurred in other countries ten or fifteen years previously." The author also observes that an increase in the use of effective contraception and earlier age at marriage have reduced the nonmarital fertility rate among the young, but not among other age-groups. Regional differences are noted, which the author suggests are primarily due to socioeconomic differences. (SUMMARY IN ENG)
Subject(s)
Age Factors , Contraception Behavior , Fertility , Geography , Illegitimacy , Marriage , Socioeconomic Factors , Contraception , Demography , Developed Countries , Economics , Europe , Family Planning Services , Population , Population Characteristics , Population Dynamics , Social Problems , SpainABSTRACT
"In the present study, we first attempt to evaluate how many deaths [in France] in a given year (1986) are brought on prematurely by drinking and smoking.... This first stage revealed a number of causes which are largely alcohol--or smoking--related. We next compare the time trends in mortality from these causes and in alcohol and tobacco consumption. Third, we consider these selected causes, along with traumas, another source of premature deaths, in relation to mortality from all causes, and follow the changes over time in levels and age structures. We thus measure the impact of these causes on the general death rates since 1950. Finally, we examine how these causes have contributed to the increase of excess male mortality during the last 40 years."
