In situ measurement of bovine serum albumin interaction with gold nanospheres

Here we present in situ observations of adsorption of bovine serum albumin (BSA) on citratestabilized gold nanospheres. We implemented scattering correlation spectroscopy as a tool to quantify changes in the nanoparticle Brownian motion resulting from BSA adsorption onto the nanoparticle surface. Protein binding was observed as an increase in the nanoparticle hydrodynamic radius. Our results indicate the formation of a protein monolayer at similar albumin concentrations as those found in human blood. Additionally, by monitoring the frequency and intensity of individual scattering events caused by single gold nanoparticles passing the observation volume, we found that BSA did not induce colloidal aggregation, a relevant result from the toxicological viewpoint. Moreover, to elucidate the thermodynamics of the gold nanoparticle-BSA association, we measured an adsorption isotherm which was best described by an anti-cooperative binding model. The number of binding sites based on this model was consistent with a BSA monolayer in its native state. In contrast, experiments using poly-ethylene glycol capped gold nanoparticles revealed no evidence for adsorption of BSA

Near-field interactions between metal nanoparticle surface plasmons and molecular excitons in thin-films: part I: absorption

In this and the following paper (parts I and II, respectively), we systematically study the interactions between surface plasmons of metal nanoparticles (NPs) with excitons in thin-films of organic media. In an effort to exclusively probe near-field interactions, we utilize spherical Ag NPs in a size-regime where far-field light scattering is negligibly small compared to absorption. In part I, we discuss the effect of the presence of these Ag NPs on the absorption of the embedding medium by means of experiment, numerical simulations, and analytical calculations, all shown to be in good agreement. We observe absorption enhancement in the embedding medium due to the Ag NPs with a strong dependence on the medium permittivity, the spectral position relative to the surface plasmon resonance frequency, and the thickness of the organic layer. By introducing a low index spacer layer between the NPs and the organic medium, this absorption enhancement is experimentally confirmed to be a near field effect In part II, we probe the impact of the Ag NPs on the emission of organic molecules by time-resolved and steady-state photoluminescence measurements

Распространенность и клинико-аллергологическая характеристика бронхиальной астмы в Восточной Сибири

The paper reports the data of a two-stage research conducted in random groups of schoolchildren (n=8247) aged 7—8 and 13—14 years and adults (n=5395) aged 20—59 years living at an industrial city (Irkutsk) and in a rural area. The first stage included a questionnaire screening (using the ISAAC and ECRHS questionnaires). During the second stage clinical and allergological as well as functional examinations were carried out in the subjects who reported asthma-like symptoms. The BA prevalence was 4.6—8.3% for children and teenagers and 3.1—5.6% for adults according to the investigation results. These results are considerably higher than statistical data given by medical institutions. The highest prevalence index was registered among the population of the industrial city, that is likely to be connected with a high level of industrial air pollution. An atopic type of the disease predominates in the etiological structure of BA and constitutes 68—73% and 89—92% among adults and children respectively. The analysis of the obtained results evidences that late diagnostics of BA takes place at the region, that is the reason of high proportion of patients with severe and complicated course of the disease.Приводятся результаты двухэтапного эпидемиологического исследования в случайных выборках школьников 7—8 и 13—14 летнего возраста (8247 чел.) и взрослых 20—59 лет (5395 чел.) в промышленно развитом городе Иркутске и в сельском районе. Первый этап включал в себя анкетный скрининг (вопросники ISAAC и ECRHS). На втором этапе лицам с астмоподобными симптомами (1753 чел.) проведено клинико-аллергологическое и функциональное исследование. По результатам исследования распространенность бронхиальной астмы (БА) составила среди детей 4,6—8,3% и среди взрослых — 3,1—5,6%, что значительно превышает показатели статистической отчетности медицинских учреждений. Наибольшие показатели распространенности БА отмечены среди населения промышленно развитого города, что связывается с высоким уровнем техногенного загрязнения его воздушной среды. В этиологической структуре БА преобладает атопическая форма заболевания, составляющая среди взрослых  больных 68—73% и среди детей — 89—92%. Анализ результатов проведенного исследования позволяет сделать вывод о поздней диагностике заболевания в регионе, что обусловливает высокий удельный вес больных с тяжелым и осложненным течением БА

Bayesian Model Selection Applied to the Analysis of Fluorescence Correlation Spectroscopy Data of Fluorescent Proteins in Vitro and in Vivo

Fluorescence correlation spectroscopy (FCS) is a powerful technique to investigate molecular dynamics with single molecule sensitivity. In particular, in the life sciences it has found widespread application using fluorescent proteins as molecularly specific labels. However, FCS data analysis and interpretation using fluorescent proteins remains challenging due to typically low signal-to-noise ratio of FCS data and correlated noise in autocorrelated data sets. As a result, naive fitting procedures that ignore these important issues typically provide similarly good fits for multiple competing models without clear distinction of which model is preferred given the signal-to-noise ratio present in the data. Recently, we introduced a Bayesian model selection procedure to overcome this issue with FCS data analysis. The method accounts for the highly correlated noise that is present in FCS data sets and additionally penalizes model complexity to prevent over interpretation of FCS data. Here, we apply this procedure to evaluate FCS data from fluorescent proteins assayed in vitro and in vivo. Consistent with previous work, we demonstrate that model selection is strongly dependent on the signal-to-noise ratio of the measurement, namely, excitation intensity and measurement time, and is sensitive to saturation artifacts. Under fixed, low intensity excitation conditions, physical transport models can unambiguously be identified. However, at excitation intensities that are considered moderate in many studies, unwanted artifacts are introduced that result in nonphysical models to be preferred. We also determined the appropriate fitting models of a GFP tagged secreted signaling protein, Wnt3, in live zebrafish embryos, which is necessary for the investigation of Wnt3 expression and secretion in development. Bayes model selection therefore provides a robust procedure to determine appropriate transport and photophysical models for fluorescent proteins when appropriate models are provided, to help detect and eliminate experimental artifacts in solution, cells, and in living organisms.National Science Foundation (U.S.). Physics of Living Systems ProgramNational Institute of Mental Health (U.S.) (Award U01MH106011

A Critical Review on the Structural Health Monitoring Methods of the Composite Wind Turbine Blades

With increasing turbine size, monitoring of blades becomes increasingly im-portant, in order to prevent catastrophic damages and unnecessary mainte-nance, minimize the downtime and labor cost and improving the safety is-sues and reliability. The present work provides a review and classification of various structural health monitoring (SHM) methods as strain measurement utilizing optical fiber sensors and Fiber Bragg Gratings (FBG’s), active/ pas-sive acoustic emission method, vibration‒based method, thermal imaging method and ultrasonic methods, based on the recent investigations and prom-ising novel techniques. Since accuracy, comprehensiveness and cost-effectiveness are the fundamental parameters in selecting the SHM method, a systematically summarized investigation encompassing methods capabilities/ limitations and sensors types, is needed. Furthermore, the damages which are included in the present work are fiber breakage, matrix cracking, delamina-tion, fiber debonding, crack opening at leading/ trailing edge and ice accre-tion. Taking into account the types of the sensors relevant to different SHM methods, the advantages/ capabilities and disadvantages/ limitations of repre-sented methods are nominated and analyzed