Assessment of the binding performance of histamine-imprinted microspheres by frontal analysis capillary electrophoresis.

Frontal analysis capillary electrophoresis was used to evaluate the binding performance of molecularly imprinted microspheres (MIM) toward its template histamine and analogs at pH 7, and compared to the high performance liquid chromatographic method. In both methods, batch binding was employed and the binding parameters were calculated from the measured concentration of unbound amine analytes and afforded comparable histamine equilibrium dissociation constants (Kd ∼ 0.4 mM). FACE was easily carried out at shorter binding equilibration time (i.e. 30 min) and without the need to separate the microspheres, circumventing laborious and, in the case of the system under study, inefficient sample filtration. It also allowed for competitive binding studies by virtue of its ability to distinctly separate intact microspheres and all tested amines which could not be resolved in HPLC. Kd 's for nonimprinted (control) microspheres (NIM) from FACE and HPLC were also comparable (∼ 0.6 mM) but at higher histamine concentrations, HPLC gave lower histamine binding. This discrepancy was attributed to inefficient filtration of the batch binding samples prior to HPLC analysis resulting in an over-estimation of the concentration of free histamine brought about by the presence of unfiltered histamine-bound microspheres.

Activation of Organic Photovoltaic Light Detectors Using Bend Leakage from Optical Fibers.

This work investigates the detection and subsequent utilization of leaked light from bends in a silica optical fiber using organic photovoltaic detectors. The optic power lost by single mode and multimode silica optical fibers was calibrated for bend radii between 1 and 7 mm for 532 and 633 nm light, exhibiting excellent agreement with previous theoretical solutions. The spatial location of maximum power leakage on the exterior of the fiber was found to exist in the same plane as the fiber, with a 10° offset from the normal. Two different organic photovoltaic detectors fabricated using a poly(3-hexylthiophene):indene-C60-bisadduct donor-acceptor blend cast from chloroform and chlorobenzene were fabricated to detect the leaked light. The two detectors exhibited different photovoltaic performances, predominantly due to different active layer thicknesses. Both devices showed sensitivity to leakage light, exhibiting voltages between 200 and 300 mV in response to leaked light from the fiber. The temporal responses of the devices were observed to differ, with a rise time from 10% to 90% of maximum voltage of 1430 µs for the chlorobenzene device, and a corresponding rise time of 490 µs for the higher performing chloroform device. The two OPVs were used to simultaneously detect leaked light from induced bends in the optical fiber, with the differing temporal profiles employed to create a unique time-correlated detection signal with enhanced security. The delay between detection of each OPV voltage could be systematically varied, allowing for either a programmable and secure single detection signal or triggering of multiple events with variable time resolution. The results reported in this study present exciting avenues toward the deployment of this simple and noninvasive optical detection system in a range of different applications.

Spatio-spectral analysis of supercontinuum generation in higher order electromagnetic modes of photonic crystal fiber.

The far-field spatial distributions of higher order electro-magnetic mode supercontinua were resolved spectrally and recorded. The supercontinua were created by precise control and direction of input pump energy offset axially from the photonic crystal fiber core. By processing the measured spectra, the spatial mode shape at each wavelength was determined. Discrete spectral features are associated with symmetrical spatial patterns arising from the host fiber geometry and suggest the electromagnetic mode pairing between the longer wavelength solitons and associated visible dispersive waves. Clear differences between supercontinua generated in fundamental and higher order electromagnetic modes exist. These data should inform theoretical studies as the solitons and the dispersive wave generated by fission may be matched by spatial orientation of the electromagnetic mode that both occupy.

Capillary electrophoresis with photodiode array detection of processable poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate aqueous dispersions.

The application of capillary electrophoresis (CE) with on-line photodiode array detection to the analysis of processable poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT/PSS) aqueous dispersions is presented. The dispersions were prepared by oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) in the presence of PSS. The separation of PEDOT/PSS complexes and PSS was achieved using sodium borate (pH 9.2) in a fused silica capillary and positive polarity. The electrophoretic behavior and UV spectra of the negatively charged complexes were correlated to the amount of PEDOT attached to PSS. The ability of CE to predict the conductivity of films produced from spin coating of PEDOT/PSS dispersions was also proposed.

A comparison of delayed self-heterodyne interference measurement of laser linewidth using Mach-Zehnder and Michelson interferometers.

Linewidth measurements of a distributed feedback (DFB) fibre laser are made using delayed self heterodyne interferometry (DHSI) with both Mach-Zehnder and Michelson interferometer configurations. Voigt fitting is used to extract and compare the Lorentzian and Gaussian linewidths and associated sources of noise. The respective measurements are w(L) (MZI) = (1.6 ± 0.2) kHz and w(L) (MI) = (1.4 ± 0.1) kHz. The Michelson with Faraday rotator mirrors gives a slightly narrower linewidth with significantly reduced error. This is explained by the unscrambling of polarisation drift using the Faraday rotator mirrors, confirmed by comparing with non-rotating standard gold coated fibre end mirrors.

Investigating behaviour and population dynamics of striped marlin (Kajikia audax) from the southwest Pacific Ocean with satellite tags.

Behaviour and distribution of striped marlin within the southwest Pacific Ocean were investigated using electronic tagging data collected from 2005-2008. A continuous-time correlated random-walk Kalman filter was used to integrate double-tagging data exhibiting variable error structures into movement trajectories composed of regular time-steps. This state-space trajectory integration approach improved longitude and latitude error distributions by 38.5 km and 22.2 km respectively. Using these trajectories as inputs, a behavioural classification model was developed to infer when, and where, 'transiting' and 'area-restricted' (ARB) pseudo-behavioural states occurred. ARB tended to occur at shallower depths (108 ± 49 m) than did transiting behaviours (127 ± 57 m). A 16 day post-release period of diminished ARB activity suggests that patterns of behaviour were affected by the capture and/or tagging events, implying that tagged animals may exhibit atypical behaviour upon release. The striped marlin in this study dove deeper and spent greater time at ≥ 200 m depth than those in the central and eastern Pacific Ocean. As marlin reached tropical latitudes (20-21 °S) they consistently reversed directions, increased swimming speed and shifted to transiting behaviour. Reversals in the tropics also coincided with increases in swimming depth, including increased time ≥ 250 m. Our research provides enhanced understanding of the behavioural ecology of striped marlin. This has implications for the effectiveness of spatially explicit population models and we demonstrate the need to consider geographic variation when standardizing CPUE by depth, and provide data to inform natural and recreational fishing mortality parameters.

Improved field scanner incorporating parabolic optics. Part 2: Experimental verification and potential for volume scanning.

We investigated the experimental performance of an afocal scan engine employing two off-axis parabolic reflectors and it was found not to introduce astigmatism when compared to a freely propagated beam. The performance of the new afocal engine is very similar to an ideal single-mirror scan engine in terms of spot size and beam spot profile (or point spread function) and has an improved flatness of field over other two-dimensional laser scan engines. The parabolic scan engine is contrasted with a comparable spherical mirror arrangement and found to produce superior performance at the intermediate image plane when focused through a scan lens. Further modeling and experimentation point toward volume scanning applications. The significant performance improvement provided by this design, now verified experimentally, will result in superior image quality for fast scanning confocal and two-photon microscopy in particular.

Calculated two-photon fluorescence correction factors for reflective scan engines.

Excitation laser spatial and temporal characteristics at the objective focal point are critical to the performance of two-photon scanning microscopes. Optical aberrations in scanning systems increase the microscope objective focal spot area and introduce pulse time broadening in the deflected beam, resulting in degradation of two-photon-induced fluorescence across the scan field. The geometrical pulse broadening is investigated for what is believed to be the first time and then combined with a focused spot area to provide a normalized two-photon fluorescence intensity correction factor. This factor, calculated using OSLO optical software, is compared for four reflective scan engines and allows compensation of the detected signal with position across the scan field. This new metric highlights that a parabolic mirror afocal relay exhibits superior performance as a reflective scan engine for two-photon scanning microscopy.

Generation and propagation of gastric slow waves.

1. Mechanisms underlying the generation and propagation of gastrointestinal slow wave depolarizations have long been controversial. The present review aims to collate present knowledge on this subject with specific reference to slow waves in gastric smooth muscle. 2. At present, there is strong agreement that interstitial cells of Cajal (ICC) are the pacemaker cells that generate slow waves. What has been less clear is the relative role of primary types of ICC, including the network in the myenteric plexus (ICC-MY) and the intramuscular network (ICC-IM). It is concluded that both ICC-MY and ICC-IM are likely to serve a major role in slow wave generation and propagation. 3. There has been long-standing controversy as to how slow waves 'propagate' circumferentially and down the gastrointestinal tract. Two mechanisms have been proposed, one being action potential (AP)-like conduction and the other phase wave-based 'propagation' resulting from an interaction of coupled oscillators. Studies made on single bundle gastric strips indicate that both mechanisms apply with relative dominance depending on conditions; the phase wave mechanism is dominant under circumstances of rhythmically generating slow waves and the AP-like propagation is dominant when the system is perturbed. 4. The phase wave mechanism (termed Ca(2+) phase wave) uses cyclical Ca(2+) release as the oscillator, with coupling between oscillators mediated by several factors, including: (i) store-induced depolarization; (ii) resultant electrical current flow/depolarization through the pacemaker cell network; and (iii) depolarization-induced increase in excitability of downstream Ca(2+) stores. An analogy is provided by pendulums in an array coupled together by a network of springs. These, when randomly activated, entrain to swing at the same frequency but with a relative delay along the row giving the impression of a propagating wave. 5. The AP-like mechanism (termed voltage-accelerated Ca(2+) wave) propagates sequentially like a conducting AP. However, it is different in that it depends on regenerative store Ca(2+) release and resultant depolarization rather than regenerative activation of voltage-dependent channels in the cell membrane. 6. The applicability of these mechanisms to describing propagation in large intact gastrointestinal tissues, where voltage-dependent Ca(2+) entry is also likely to be functional, is discussed.

Improved field scanner incorporating parabolic optics. Part 1: simulation.

An unobstructed afocal scanning system design employing two off-axis parabolic reflectors as relay optics between two flat scan mirrors is proposed and investigated using OSLO optical software. It is found that, with a symmetric arrangement of the parabolic reflectors and appropriate selection of the first scan mirror rotational axis, the system provides linear scan lines at the image surface and excellent point spread function results in all scan positions. The design is functionally equivalent to a single-mirror scan engine and superior in every metric to a comparable dimension spherical mirror arrangement. This design is suited to two-dimensional laser scan engines and for confocal and two-photon microscopy in particular.

Pneumonitis following grease gun injury.

Grease gun trauma often involves subcutaneous injection of the grease because of the high pressures required for its industrial application. The case is presented of a man who developed a pneumonitis shortly after sustaining a grease gun injury, with injection of grease into his upper thigh associated with significant vascular damage. Pneumonitis has not previously been reported with this type of injury, and is likely to represent a systemic reaction to the local inflammatory response. Management of these injuries should incorporate early debridement with anticipation of underlying vascular trauma, and also an awareness of the potential systemic complications.