Laser-induced nucleation promotes crystal growth of anhydrous sodium bromide

We report on a study of crystal hydrate formation in supersaturated aqueous sodium bromide using different methods to induce nucleation: mechanical shock-induced nucleation (MSIN), nucleation by ultrasound (sonocrystallization), non-photochemical laser-induced nucleation (NPLIN) and laser-trapping nucleation. The most stable crystal form at room temperature is known to be sodium bromide dihydrate (DH) and this form was favoured (>95%) through spontaneous nucleation or mechanical shock. Sonocrystallization favoured DH crystals (74%). Remarkably both laser-induced nucleation methods showed a strong preference (>90%) for anhydrous (AH) crystals. The nucleation mechanisms are discussed with reference to the solution–solid phase diagram. For laser-trapping nucleation, the results are consistent with previous studies showing that nucleation is preceded by formation of a localised volume of increased solute concentration. The common mechanistic feature linking sonocrystallization, MSIN and NPLIN is cavitation. The preference for AH sodium bromide suggests that nanosecond laser pulses produce cavitation events with more thermal energy compared to the other methods. The results demonstrate the value of laser-induced nucleation in controlling crystal hydrate growth and provide new understanding of the nucleation mechanisms

Nautilus pompilius Life History and Demographics at the Osprey Reef Seamount, Coral Sea, Australia

Nautiloids are the subject of speculation as to their threatened status arising from the impacts of targeted fishing for the ornamental shell market. Life history knowledge is essential to understand the susceptibility of this group to overfishing and to the instigation of management frameworks. This study provides a comprehensive insight into the life of Nautilus in the wild. At Osprey Reef from 1998–2008, trapping for Nautilus was conducted on 354 occasions, with 2460 individuals of one species, Nautilus pompilius, captured and 247 individuals recaptured. Baited remote underwater video systems (BRUVS) were deployed on 15 occasions and six remotely operated vehicle (ROV) dives from 100–800 m were conducted to record Nautilus presence and behavior. Maturity, sex and size data were recorded, while measurements of recaptured individuals allowed estimation of growth rates to maturity, and longevity beyond maturity. We found sexual dimorphism in size at maturity (males: 131.9±SD = 2.6 mm; females: 118.9±7.5 mm shell diameter) in a population dominated by mature individuals (58%). Mean growth rates of 15 immature recaptured animals were 0.061±0.023 mm day−1 resulting in an estimate of around 15.5 years to maturation. Recaptures of mature animals after five years provide evidence of a lifespan exceeding 20 years. Juvenile Nautilus pompilius feeding behavior was recorded for the first time within the same depth range (200–610 m) as adults. Our results provide strong evidence of a K-selected life history for Nautilus from a detailed study of a ‘closed’ wild population. In conjunction with population size and density estimates established for the Osprey Reef Nautilus, this work allows calculations for sustainable catch and provides mechanisms to extrapolate these findings to other extant nautiloid populations (Nautilus and Allonautilus spp.) throughout the Indo-Pacific

Complete Genome Sequences of Arcobacter butzleri ED-1 and Arcobacter sp Strain L, Both Isolated from a Microbial Fuel Cell

Arcobacter butzleri strain ED-1 is an exoelectrogenic epsilonproteobacterium isolated from the anode biofilm of a microbial fuel cell. Arcobacter sp. strain L dominates the liquid phase of the same fuel cell. Here we report the finished and annotated genome sequences of these organisms

Predicting Infiltration and Surface Runoff from Reconstructed Spoils and Soils

A laboratory system was fabricated to measure infiltration and runoff from spoil and soil profiles constructed in rectangular bins. Construction, calibration and operation of a rainfall simulator is discussed and instrumentation used to measure transient infiltration and transmittance of water through experimental profiles is described. Spoil and soil materials from surface mines in Eastern and Western Kentucky were transported to the laboratory and used in constructing experimental profiles in rectangular bins (0.91 x 1.83 x 1.07 m). An extensive series of infiltration experiments were conducted utilizing a rainfall simulator and soil moisture monitoring instrumentation. A dual probe gamma density gauge was used to measure moisture content and tensiometers were used to measure soil matric suction. Initial moisture content, bulk density and rainfall rate were varied and respective responses of infiltration characteristics determined. Extremely low infiltration rates in Western Kentucky spoil material was attributed to relatively high bulk densities and well-graded particle constituency. Conversely, extremely high infiltration rates were observed for Eastern Kentucky shale material even at very high bulk densities. The sandstone material, however, exhibited infiltration rates of the same order of magnitude as that of Western Kentucky spoil material. Soil water characteristic curves were developed using the Brooks-Corey and Gardner procedures, based upon desortpion tensiometer data. Unsaturated hydraulic conductivity values were determined using the plane of zero flux procedure and compared with predictions resulting from models described by Campbell, Burdine and Mualem for situations involving reconstructed soil and spoil materials. There was generally good agreement between the models and plane of zero flux results, and excellent agreement with Campbell\u27s predictions. The infiltration process was modeled with the SCS curve number method, a modified form of Holtan\u27s equation, the Green-Ampt model and Richard\u27s equation. SCS curve numbers were determined by fitting the method to the observed results. Richards\u27 equation gave very good estimates of the infiltration process through the spoil profiles, but was only slightly better than the Green-Ampt model. None .of the models worked well for the profiles where macropore flow occurred through a two layer topsoil over spoil system

Comparison of Daily Water Table Depth Prediction by Four Simulation Models

The Agricultural Drainage And Pesticide Transport (ADAPT) model was compared to the water management simulation models DRAINMOD, SWATREN, and PREFLO. SWATREN and PREFLO are one-dimensional finite-difference models while ADAPT and DRAINMOD are one-dimensional mass balance models. ADAPT, an extension of the computer model GLEAMS, also provides chemical transport information. All four models were tested against field data from Aurora, North Carolina. Observed water table depth data were collected during 1973 through 1977 from a water table management field experiment with three subsurface drain spacing treatments of 7.5, 15, and 30 m. Both the standard error of estimate and the average absolute deviation were computed between measured and predicted midpoint water table depths. For the five-year period ADAPT, DRAINMOD, SWATREN, and PREFLO had standard errors of estimated water table depth of 0.18, 0.19, 0.19, and 0.18 m and absolute deviations of 0.14, 0.14, 0.14, and 0.14 m, respectively. The results show good agreement between the models for this experimental site and encourage the further adoption of ADAPT to predict chemical transport

Biophysical Aspects of Resource Acquisition and Competition in Algal Mixotrophs

Mixotrophic organisms combine autotrophic and heterotrophic nutrition and are abundant in both freshwater and marine environments. Recent observations indicate that mixotrophs constitute a large fraction of the biomass, bacterivory, and primary production in oligotrophic environments. While mixotrophy allows greater flexibility in terms of resource acquisition, any advantage must be traded off against an associated increase in metabolic costs, which appear to make mixotrophs uncompetitive relative to obligate autotrophs and heterotrophs. Using an idealized model of cell physiology and community competition, we identify one mechanism by which mixotrophs can effectively outcompete specialists for nutrient elements. At low resource concentrations, when the uptake of nutrients is limited by diffusion toward the cell, the investment in cell membrane transporters can be minimized. In this situation, mixotrophs can acquire limiting elements in both organic and inorganic forms, outcompeting their specialist competitors that can utilize only one of these forms. This advantage can be enough to offset as much as a twofold increase in additional metabolic costs incurred by mixotrophs. This mechanism is particularly relevant for the maintenance of mixotrophic populations and productivity in the highly oligotro phic subtropical oceans.United States. National Aeronautics and Space AdministrationGordon and Betty Moore Foundatio

1064 nm Dispersive Raman Microspectroscopy and Optical Trapping of Pharmaceutical Aerosols.

Raman spectroscopy is a powerful tool for investigating chemical composition. Coupling Raman spectroscopy with optical microscopy (Raman microspectroscopy) and optical trapping (Raman tweezers) allows microscopic length scales and, hence, femtolitre volumes to be probed. Raman microspectroscopy typically uses UV/visible excitation lasers, but many samples, including organic molecules and complex tissue samples, fluoresce strongly at these wavelengths. Here we report the development and application of dispersive Raman microspectroscopy designed around a near-infrared continuous wave 1064 nm excitation light source. We analyze microparticles (1-5 μm diameter) composed of polystyrene latex and from three real-world pressurized metered dose inhalers (pMDIs) used in the treatment of asthma: salmeterol xinafoate (Serevent), salbutamol sulfate (Salamol), and ciclesonide (Alvesco). For the first time, single particles are captured, optically levitated, and analyzed using the same 1064 nm laser, which permits a convenient nondestructive chemical analysis of the true aerosol phase. We show that particles exhibiting overwhelming fluorescence using a visible laser (514.5 nm) can be successfully analyzed with 1064 nm excitation, irrespective of sample composition and irradiation time. Spectra are acquired rapidly (1-5 min) with a wavelength resolution of 2 nm over a wide wavenumber range (500-3100 cm-1). This is despite the microscopic sample size and low Raman scattering efficiency at 1064 nm. Spectra of individual pMDI particles compare well to bulk samples, and the Serevent pMDI delivers the thermodynamically preferred crystal form of salmeterol xinafoate. 1064 nm dispersive Raman microspectroscopy is a promising technique that could see diverse applications for samples where fluorescence-free characterization is required with high spatial resolution

Quantitative Assessment of Experimental Ocular Inflammatory Disease

Ocular inflammation imposes a high medical burden on patients and substantial costs on the health-care systems that mange these often chronic and debilitating diseases. Many clinical phenotypes are recognized and classifying the severity of inflammation in an eye with uveitis is an ongoing challenge. With the widespread application of optical coherence tomography in the clinic has come the impetus for more robust methods to compare disease between different patients and different treatment centers. Models can recapitulate many of the features seen in the clinic, but until recently the quality of imaging available has lagged that applied in humans. In the model experimental autoimmune uveitis (EAU), we highlight three linked clinical states that produce retinal vulnerability to inflammation, all different from healthy tissue, but distinct from each other. Deploying longitudinal, multimodal imaging approaches can be coupled to analysis in the tissue of changes in architecture, cell content and function. This can enrich our understanding of pathology, increase the sensitivity with which the impacts of therapeutic interventions are assessed and address questions of tissue regeneration and repair. Modern image processing, including the application of artificial intelligence, in the context of such models of disease can lay a foundation for new approaches to monitoring tissue health

Atrazine and Alachlor Dissipation Rates from Field Experiments

Chemical transport is being monitored in the root zone of three agricultural management systems at the Ohio Management Systems Evaluation Area (OMSEA). Atrazine and alachlor concentration data from soil cores taken to a depth of 0.9 m and partitioned into the increments of 0.0 to 0.15, 0.15 to 0.3, 0.45 to 0.6, and 0.75 to 0.9 m show the herbicides remained in the top 0.15 m of the profile during the 1991 and 1992 growing seasons. The slow movement of herbicides was partly due to below normal rainfall during the period. Since the herbicides have not been transported out of the soil profile, dissipation rates could be determined from the field observations. The data collected follow first-order kinetics in the dissipation of atrazine during the 1991 and 1992 growing season and of alachlor during the 1991 growing season for the two- to three-month period following chemical application. The computed rate constant, k, was 0.02 d–1 and half-life, t1/2, was 35 days for atrazine for both years. A rate constant of 0.04 d–1 and half-life of 17 days were computed for alachlor. The degradation rates became slower with residence time in the soil as a result of decreased availability from sorption/binding in the soil