Microfluidic integration of photonic crystal fibers for online photochemical reaction analysis

Liquid-filled hollow-core photonic crystal fibers (HC-PCFs) are perfect optofluidic channels, uniquely providing low-loss optical guidance in a liquid medium. As a result, the overlap of the dissolved specimen and the intense light field in the micronsized core is increased manyfold compared to conventional bioanalytical techniques, facilitating highly-efficient photoactivation processes. Here we introduce a novel integrated analytical technology for photochemistry by microfluidic coupling of a HC-PCF nanoflow reactor to supplementary detection devices. Applying a continuous flow through the fiber, we deliver photochemical reaction products to a mass spectrometer in an online and hence rapid fashion, which is highly advantageous over conventional cuvette-based approaches

Fluorescence-based remote irradiation sensor in liquid-filled hollow-core photonic crystal fiber

We report an irradiation sensor based on a fluorescent “flying particle” that is optically trapped and propelled inside the core of a water-filled hollow-core photonic crystal fiber. When the moving particle passes through an irradiated region, its emitted fluorescence is captured by guided modes of the fiber core and so can be monitored using a filtered photodiode placed at the fiber end. The particle speed and position can be precisely monitored using in-fiber Doppler velocimetry, allowing the irradiation profile to be measured to a spatial resolution of ~10 $\mu$m. The spectral response can be readily adjusted by appropriate choice of particle material. Using dye-doped polystyrene particles, we demonstrate detection of green (532 nm) and ultraviolet (340 nm) light.Richard Zeltner acknowledges funding from the Cluster of Excellence “Engineering of Advanced Materials” (www.eam.uni-erlangen.de) at the University of ErlangenNuremberg.This is the author accepted manuscript. The final version is available from AIP Publishing via http://dx.doi.org/10.1063/1.495359

Fluorescence-based flying-particle sensor in liquid-filled hollow-core photonic crystal fiber

© 2016 OSA. We present a novel irradiation sensor based on a fluorescent microparticle that is optically guided inside the core of a liquid-filled photonic crystal fiber. We demonstrate irradiance measurements with spatial resolution of ∼10 μm

Stable Immobilization of Size-Controlled Bimetallic Nanoparticles in Photonic Crystal Fiber Microreactor

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. The possibility of immobilizing ex situ-synthesized colloidal bimetallic nanoparticles (NPs) of well-defined characteristics inside hollow core photonic crystal fiber (HC-PCF) microreactors is demonstrated. With the developed method, PtNi clusters remain strongly attached to the fiber core and can be used as active catalysts for the hydrogenation of an azobenzene dye. The study revealed that optical transmission exhibits a size-dependent behavior, i.e., smaller NPs bring in less optical signal loss. Sufficient light transmission was achieved for all particle sizes. Furthermore, with these catalytic PCF microreactors, kinetic data can be obtained with a much lower amount of precious metals compared to a conventional batch reactor, opening a new pathway for in situ catalyst screening

Excitation of higher-order modes in optofluidic hollow-core photonic crystal fiber

Higher-order modes are controllably excited in water-filled kagomè-, bandgap-style, and simplified hollow-core photonic crystal fibers (HC-PCF). A spatial light modulator is used to create amplitude and phase distributions that closely match those of the fiber modes, resulting in typical launch efficiencies of 10–20% into the liquid-filled core. Modes, excited across the visible wavelength range, closely resemble those observed in air-filled kagomè HC-PCF and match numerical simulations. These results provide a framework for spatially-resolved sensing in HC-PCF microreactors and fiber-based optical manipulation

A new method to measure Bowen ratios using high-resolution vertical dry and wet bulb temperature profiles

The Bowen ratio surface energy balance method is a relatively simple method to determine the latent heat flux and the actual land surface evaporation. The Bowen ratio method is based on the measurement of air temperature and vapour pressure gradients. If these measurements are performed at only two heights, correctness of data becomes critical. In this paper we present the concept of a new measurement method to estimate the Bowen ratio based on vertical dry and wet bulb temperature profiles with high spatial resolution. A short field experiment with distributed temperature sensing (DTS) in a fibre optic cable with 13 measurement points in the vertical was undertaken. A dry and a wetted section of a fibre optic cable were suspended on a 6 m high tower installed over a sugar beet trial plot near Pietermaritzburg (South Africa). Using the DTS cable as a psychrometer, a near continuous observation of vapour pressure and air temperature at 0.20 m intervals was established. These data allowed the computation of the Bowen ratio with a high spatial and temporal precision. The daytime latent and sensible heat fluxes were estimated by combining the Bowen ratio values from the DTS-based system with independent measurements of net radiation and soil heat flux. The sensible heat flux, which is the relevant term to evaluate, derived from the DTS-based Bowen ratio (BR-DTS) was compared with that derived from co-located eddy covariance (<i>R</i>² = 0.91), surface layer scintillometer (<i>R</i>² = 0.81) and surface renewal (<i>R</i>² = 0.86) systems. By using multiple measurement points instead of two, more confidence in the derived Bowen ratio values is obtained

Long-range optical trapping and binding of microparticles in hollow-core photonic crystal fibre.

Optically levitated micro- and nanoparticles offer an ideal playground for investigating photon-phonon interactions over macroscopic distances. Here we report the observation of long-range optical binding of multiple levitated microparticles, mediated by intermodal scattering and interference inside the evacuated core of a hollow-core photonic crystal fibre (HC-PCF). Three polystyrene particles with a diameter of 1 µm are stably bound together with an inter-particle distance of ~40 μm, or 50 times longer than the wavelength of the trapping laser. The levitated bound-particle array can be translated to-and-fro over centimetre distances along the fibre. When evacuated to a gas pressure of 6 mbar, the collective mechanical modes of the bound-particle array are able to be observed. The measured inter-particle distance at equilibrium and mechanical eigenfrequencies are supported by a novel analytical formalism modelling the dynamics of the binding process. The HC-PCF system offers a unique platform for investigating the rich optomechanical dynamics of arrays of levitated particles in a well-isolated and protected environment.This work was supported by Max Planck Society. R. Z. acknowledges funding from the Cluster of Excellence "Engineering of Advanced Materials" at the Friedrich-Alexander University in Erlangen, Germany

The specialist predator protects termite colonies from generalist predators

Contains fulltext : 143439.pdf (publisher's version ) (Open Access)BACKGROUND: Children of parents with a substance use disorder (CPSUD) are at increased risk for developing problematic substance use later in life. Endophenotypes may help to clarify the mechanism behind this increased risk. However, substance use and externalizing symptoms may confound the relation between dysregulated physiological stress responding and familial risk for substance use disorders (SUDs). METHODS: We examined whether heart rate (HR) responses differed between CPSUDs and controls. Participants (aged 11-20years) were CPSUDs (N=75) and controls (N=363), semi-matched on the basis of sex, socioeconomic status, and ethnicity. HR was measured continuously during a psychosocial stress procedure. Substance use and externalizing symptoms were self-reported and mother-reported, respectively. RESULTS: A piecewise, mixed-effects model was fit for HR across the stress procedure, with fixed effects for HR reactivity and HR recovery. CPSUDs showed a blunted HR recovery. CPSUDs reported drinking more frequently, were more likely to use tobacco daily, were more likely to report ever use of cannabis and used cannabis more frequently, and exhibited more externalizing symptoms. These variables did not confound the relation between familial risk for SUDs and a blunted HR recovery. CONCLUSION: Our findings suggest dysregulated autonomic nervous system (ANS) responding in CPSUDs and contribute to the accumulating evidence for ANS dysregulation as a potential endophenotype for SUDs.9 p

Stressful Family Environments and Children's Behavioral Control: A Multimethod Test and Replication Study With Twins.

Young children's behavioral control predicts a broad range of developmental outcomes in child- and adulthood. It is therefore important to study how individual differences in behavioral control arise. Previous studies suggest that there are both genetic and environmental influences, which were estimated in the current study using a sample of mono- and dizygotic same-sex twins. Furthermore, we examined the associations between indicators of a stressful family environment like household chaos, parenting daily hassles, and parental depressive symptoms and children's behavioral control in 2 samples. Children of the same twin pair were randomly divided over 2 samples; a test (N = 201, 48.3% boys, M age 46.53 months) and replication sample (N = 201, 49.8% boys, M age 46.06 months). Both parents reported on their children's effortful control via the Child Behavior Questionnaire and children's cheating behavior was observed during a throwing game. We found that AE models fitted the data for effortful control (A = 31%, E = 69%) and cheating (A = 16%, E = 84%) best. Path analyses revealed that children of parents experiencing more parenting daily hassles and depressive symptoms had lower levels of effortful control in the test sample. Furthermore, we found that children growing up in more chaotic households (parent report) had an increased risk of being in the cheating group versus the possible intention to cheat group in the test sample. These results were partially replicated. We suggest that the role of stressful family environments in the development of behavioral control should be considered when setting up prevention and intervention programs targeting children's behavioral control. (PsycINFO Database RecordDevelopment Psychopathology in context: famil