Light dilution via wavelength management for efficient high-density photobioreactors.

The spectral distribution of light influences microalgae productivity; however, development of photobioreactors has proceeded largely without regard to spectral optimization. Here, we use monochromatic light to quantify the joint influence of path length, culture density, light intensity, and wavelength on productivity and efficiency in Synechococcus elongatus. The productivity of green light was ∼4× that of red at the highest levels of culture density, depth, and light intensity. This performance is attributed to the combination of increased dilution and penetration of this weakly absorbed wavelength over a larger volume fraction of the reactor. In contrast, red light outperformed other wavelengths in low-density cultures with low light intensities. Low-density cultures also adapted more rapidly to reduce absorption of longer wavelengths, allowing for prolonged cultivation. Taken together, these results indicate that, particularly for artificially lit photobioreactors, wavelength needs to be included as a critical operational parameter to maintain optimal performance. Biotechnol. Bioeng. 2017;114: 1160-1169. © 2017 Wiley Periodicals, Inc.

Adolescents' views and experiences of treatments for Type 2 diabetes: a qualitative study.

AIM: To explore adolescents' views and experiences of different treatments for Type 2 diabetes, in order to improve treatment concordance and consider how the current treatment pathway for adolescent Type 2 diabetes could be improved. METHODS: In-depth interviews were held with 12 adolescents who had been diagnosed with Type 2 diabetes. Adolescents were sampled from a UK cohort study. Data were analysed thematically. RESULTS: Interviewees struggled to maintain lifestyle changes. Insulin, metformin and liraglutide were described as effective but, in some cases, as resulting in side effects. Injected treatments were viewed less favourably than oral medications. Weight loss surgery was considered an acceptable treatment for obese adolescents who had tried other treatments for their diabetes. It was apparent that some adolescents had not been surprised by their diagnosis and did not fully appreciate the implications of having diabetes. It was also evident that some individuals had not told peers about their diagnosis due to fearing how they would react. Factors identified as improving treatment concordance included reminders and viewing treatment as effective and easy to take. CONCLUSIONS: Adolescents want treatments that are effective, discrete, easy to take and do not make them different from their peers. As liraglutide was described as effective, and surgery viewed as acceptable in certain circumstances, greater consideration should be given to their potential role in treating adolescent Type 2 diabetes. Practitioners need to ensure that adolescents appreciate the implications of having diabetes and may want to address adolescents' concerns regarding how others view this condition.

Induced detachment of coalescing droplets on superhydrophobic surfaces.

Coalescence of a falling droplet with a stationary sessile droplet on a superhydrophobic surface is investigated by a combined experimental and numerical study. In the experiments, the droplet diameter, the impact velocity, and the distance between the impacting droplets were controlled. The evolution of surface shape during the coalescence of two droplets on the superhydrophobic surface is captured using high speed imaging and compared with numerical results. A two-phase volume of fluid (VOF) method is used to determine the dynamics of droplet coalescence, shape evaluation, and contact line movement. The spread length of two coalesced droplets along their original center is also predicted by the model and compared well with the experimental results. The effect of different parameters such as impact velocity, center to center distance, and droplet size on contact time and restitution coefficient are studied and compared to the experimental results. Finally, the wetting and the self-cleaning properties of superhydrophobic surfaces have been investigated. It has been found that impinging water drops with very small amount of kinetic impact energy were able to thoroughly clean these surfaces.

Two-dimensional planar swimming selects for high DNA integrity sperm.

Selection of high-quality sperm is critical to the success of assisted reproductive technologies. Clinical screening for top sperm has long focused on sperm swimming ability when following boundaries or when fully free of constraints. In this work, we demonstrate a sperm selection approach with parallel 2 µm tall confined selection channels that prohibit rotation of the sperm head and require planar swimming. We demonstrate that a planar swimming subpopulation of sperm capable of entering and navigating these channels has DNA integrity superior to the freely-swimming motile or raw sperm populations over a wide range of semen sample qualities. The DNA integrity of the selected sperm was significantly higher than that of the corresponding raw samples for donor samples and clinical patient samples, respectively. In side-by-side testing, this method outperforms current clinical selection methods, density gradient centrifugation and swim-up, as well as sperm selected via general motility. Planar swimming represents a viable sperm selection mechanism with the potential to improve outcomes for couples and offspring.

A Platform for High-Throughput Assessments of Environmental Multistressors.

A platform compatible with microtiter plates to parallelize environmental treatments to test the complex impacts of multiple stressors, including parameters relevant to climate change and point source pollutants is developed. This platform leverages (1) the high rate of purely diffusive gas transport in aerogels to produce well-defined centimeter-scale gas concentration gradients, (2) spatial light control, and (3) established automated liquid handling. The parallel gaseous, aqueous, and light control provided by the platform is compatible with multiparameter experiments across the life sciences. The platform is applied to measure biological effects in over 700 treatments in a five-parameter full factorial study with the microalgae Chlamydomonas reinhardtii. Further, the CO2 response of multicellular organisms, Lemna gibba and Artemia salina under surfactant and nanomaterial stress are tested with the platform.

A penalty on photosynthetic growth in fluctuating light.

Fluctuating light is the norm for photosynthetic organisms, with a wide range of frequencies (0.00001 to 10 Hz) owing to diurnal cycles, cloud cover, canopy shifting and mixing; with broad implications for climate change, agriculture and bioproduct production. Photosynthetic growth in fluctuating light is generally considered to improve with increasing fluctuation frequency. Here we demonstrate that the regulation of photosynthesis imposes a penalty on growth in fluctuating light for frequencies in the range of 0.01 to 0.1 Hz (organisms studied: Synechococcus elongatus and Chlamydomonas reinhardtii). We provide a comprehensive sweep of frequencies and duty cycles. In addition, we develop a 2nd order model that identifies the source of the penalty to be the regulation of the Calvin cycle - present at all frequencies but compensated at high frequencies by slow kinetics of RuBisCO.

Microfluidics for sperm analysis and selection.

Infertility is a growing global health issue with far-reaching socioeconomic implications. A downward trend in male fertility highlights the acute need for affordable and accessible diagnosis and treatment. Assisted reproductive technologies are effective in treating male infertility, but their success rate has plateaued at ∼33% per cycle. Many emerging opportunities exist for microfluidics - a mature technology in other biomedical areas - in male infertility diagnosis and treatment, and promising microfluidic approaches are under investigation for addressing male infertility. Microfluidic approaches can improve our fundamental understanding of sperm motion, and developments in microfluidic devices that use microfabrication and sperm behaviour can aid semen analysis and sperm selection. Many burgeoning possibilities exist for engineers, biologists, and clinicians to improve current practices for infertility diagnosis and treatment. The most promising avenues have the potential to improve medical practice, moving innovations from research laboratories to clinics and patients in the near future.

Calibration of X-ray spectrometers for opacity experiments at the Orion laser facility (invited).

Accurately calibrated and characterised x-ray diagnostics are a key requirement in the fielding of experiments on the Orion laser where absolute measurements of x-ray emission are used to underpin the validity of models of emissivity and opacity. Diffraction crystals are used in spectrometers on Orion to record the dispersed spectral features emitted by the laser produced plasma to obtain a measurement of the plasma conditions. The ability to undertake diffraction crystal calibrations supports the successful outcome of these Orion experiments. This paper details the design and commissioning of a system to undertake these calibrations in the energy range 2.0 keV to approximately 8.5 keV. Improvements to the design are detailed which will extend the commissioned range of energies to below 1 keV.

Dual gradients of light intensity and nutrient concentration for full-factorial mapping of photosynthetic productivity.

Optimizing bioproduct generation from microalgae is complicated by the myriad of coupled parameters affecting photosynthetic productivity. Quantifying the effect of multiple coupled parameters in full-factorial fashion requires a prohibitively high number of experiments. We present a simple hydrogel-based platform for the rapid, full-factorial mapping of light and nutrient availability on the growth and lipid accumulation of microalgae. We accomplish this without microfabrication using thin sheets of cell-laden hydrogels. By immobilizing the algae in a hydrogel matrix we are able to take full advantage of the continuous spatial chemical gradient produced by a diffusion-based gradient generator while eliminating the need for chambers. We map the effect of light intensities between 0 µmol m(-2) s(-1) and 130 µmol m(-2) s(-1) (∼28 W m(-2)) coupled with ammonium concentrations between 0 mM and 7 mM on Chlamydomonas reinhardtii. Our data set, verified with bulk experiments, clarifies the role of ammonium availability on the photosynthetic productivity Chlamydomonas reinhardtii, demonstrating the dependence of ammonium inhibition on light intensity. Specifically, a sharp optimal growth peak emerges at approximately 2 mM only for light intensities between 80 and 100 µmol m(-2) s(-1)- suggesting that ammonium inhibition is insignificant at lower light intensities. We speculate that this phenomenon is due to the regulation of the high affinity ammonium transport system in Chlamydomonas reinhardtii as well as free ammonia toxicity. The complexity of this photosynthetic biological response highlights the importance of full-factorial data sets as enabled here.

Predominance of sperm motion in corners.

Sperm migration through the female tract is crucial to fertilization, but the role of the complex and confined structure of the fallopian tube in sperm guidance remains unknown. Here, by confocal imaging microchannels head-on, we distinguish corner- vs. wall- vs. bulk-swimming bull sperm in confined geometries. Corner-swimming dominates with local areal concentrations as high as 200-fold that of the bulk. The relative degree of corner-swimming is strongest in small channels, decreases with increasing channel size, and plateaus for channels above 200 µm. Corner-swimming remains predominant across the physiologically-relevant range of viscosity and pH. Together, boundary-following sperm account for over 95% of the sperm distribution in small rectangular channels, which is similar to the percentage of wall swimmers in circular channels of similar size. We also demonstrate that wall-swimming sperm travel closer to walls in smaller channels (~100 µm), where the opposite wall is within the hydrodynamic interaction length-scale. The corner accumulation effect is more than the superposition of the influence of two walls, and over 5-fold stronger than that of a single wall. These findings suggest that folds and corners are dominant in sperm migration in the narrow (sub-mm) lumen of the fallopian tube and microchannel-based sperm selection devices.

Microalgae on display: a microfluidic pixel-based irradiance assay for photosynthetic growth.

Microalgal biofuel is an emerging sustainable energy resource. Photosynthetic growth is heavily dependent on irradiance, therefore photobioreactor design optimization requires comprehensive screening of irradiance variables, such as intensity, time variance and spectral composition. Here we present a microfluidic irradiance assay which leverages liquid crystal display technology to provide multiplexed screening of irradiance conditions on growth. An array of 238 microreactors are operated in parallel with identical chemical environments. The approach is demonstrated by performing three irradiance assays. The first assay evaluates the effect of intensity on growth, quantifying saturating intensity. The second assay quantifies the influence of time-varied intensity and the threshold frequency for growth. Lastly, the coupled influence of red-blue spectral composition and intensity is assessed. Each multiplexed assay is completed within three days. In contrast, completing the same number of experiments using conventional incubation flasks would require several years. Not only does our approach enable more rapid screening, but the short optical path avoids self-shading issues inherent to flask based systems.

Student learning styles in anatomy and physiology courses: Meeting the needs of nursing students.

Anatomy and Physiology is a core course in pre-registration nursing programs, yet many students have difficulty successfully negotiating the large volume of content and the complex concepts in these bioscience courses. Typically students perform poorly in these 'threshold' courses', despite multiple interventions to support student engagement. Investigation of the shortcomings in these courses, based on feedback from students indicated several key areas of difficulty in the course, especially focused around a relative lack of hands-on 'concrete' activities in laboratories and tutorials. To attempt to address this, academic and technical staff developed activities for students that promoted discussion and allowed students to interact easily and repetitively with content. Interactive tables and posters that needed to be labelled or 'filled-in' using pre-prepared Velcro dots, as well as pre-prepared flash cards to promote group work, were some examples of the activities used to enhance student experiences and promote hands-on learning. Over the academic year of 2013 these activities were introduced into the laboratory and tutorial classes for first year Bachelor of Nursing anatomy and physiology students. Staff and student participants positively rated implementation of these new activities on surveys, as they allowed them to explore the difficult aspects of anatomy and physiology, utilising various learning styles that may have been neglected in the past.

Two families with an autosomal dominant inheritance pattern for papillary carcinoma of the thyroid.

BACKGROUND: Papillary carcinoma of the thyroid (PTC) is the most prevalent malignancy of the thyroid gland. Although the majority of lesions are sporadic tumors, an established relationship exists between familial adenomatous polyposis (FAP) and PTC. Moreover, some authors postulate the existence of familial PTC as a distinct entity. Evidence for this is limited, however, there being few well characterized descriptions of pedigrees with high prevalence of PTC. AIMS: The objective of the present study was to examine an apparent heritable predisposition to PTC occurring in two Tasmanian families in which PTC occurs commonly. METHODS: Pedigree charts were constructed for both families and the medical records of the members reviewed. RESULTS: In Pedigree I, 7 of 25 members had PTC (6 of these had coexisting multinodular goiter (MNG), and 11 others had MNG. In Pedigree II, identical male twins and their daughters had PTC. CONCLUSIONS: In both families there is evidence of autosomal dominant inheritance of PTC. The association of PTC with MNG suggests a possible role for MNG in tumor pathogenesis in hereditary PTC. The majority of the patients were diagnosed with PTC before commencement of prospective screening, indicating clinically relevant disease in the families described.

The effect of bile on the crystallisation of calcium carbonate, a constituent of gallstones.

When calcium and bicarbonate ions were mixed at room temperature (approximately 20 degrees C) to give concentrations of 4 mmol/1 and 21 mmol/1 respectively and the pH of the solution was kept at 8.3, vaterite, a form of calcium carbonate, was precipitated almost immediately as spheres of diameter 45 micron. The crystallisation of this material could be slowed down by adding to the crystallising medium small amounts of pyrophosphate or citrate which often inhibit crystal growth. High concentrations of sodium chloride (90 mmol/1) did not, however, affect the reaction. Very small amounts of gallbladder bile from patients with only cholesterol on the surface of their gallstones inhibited the crystallisation of calcium carbonate, and the size of the spheres was only 0.37 times those produced in water. The activity of the bile could be attributed to material with a molecular weight greater than 10 000. On the other hand, bile from patients having some calcium carbonate on the gallstone surface had less activity than comparable amounts of bile from patients with only cholesterol in this area. The active material may, therefore, play a part in preventing the deposition of calcium carbonate in gallstones.

An assay method for the measurement of urinary inhibitors of calcium phosphate formation.

An assay method has been developed for studying quantitatively the formation of calcium phosphate. The method will detect both substances which affect the solubility of calcium phosphate and substances which affect the crystal growth of the material. It is sensitive as or more sensitive than other methods described in the literature for detecting such compounds.

The estimation of D-isocitric acid in urine using isocitrate dehydrogenase.

The amount of D-isocitric acid in urine has been estimated using the enzyme isocitrate dehydrogenase. The technique is rapid and easy to perform. Reproducibility of results was good and results from recovery experiments were excellent. The concentration range for early morning urine samples from normal adults was 0.08-0.65 mmol/l with a mean of 0.29 mmol/l.

Isolation and identification of some urinary inhibitors of calcium phosphate formation.

Normal urine has been examined for substances which inhibit formation of calcium phosphate. A separation scheme involving ultrafiltration, precipitation, electrophoresis and paper chromatography was devised to isolate these substances. Contrary to what has been suggested in the literature for many years, the urines examined did not contain a potent unidentified inhibitor. The major anionic inhibitors were citric acid, pyrophosphate and isocitric acid. These substances together with a small contribution from the cations appeared to account for most, if not all, of the inhibitory activity of urine.

Observer variability in the measurement of the size of intracranial aneurysms using power TCD.

This study assessed the observer variability for measurement of intracranial aneurysmal size visualized on color "power" Transcranial Doppler Ultrasound (TCD). Patients with recent subarachnoid hemorrhage underwent color "power" TCD blind to angiography. Identified aneurysms were measured from the frozen image (in real time or from video tape) using the trackball function. Two observers measured the maximum (systolic) and minimum (end diastolic) area of each aneurysm, and an adjacent reference artery. Each observer was blind to the other's results. Interobserver variability was assessed using the Bland and Altman technique. Thirty-nine aneurysms were identified in 32 patients in 10 months. The maximum cross-sectional area of the aneurysm was 38:41 mm2 (observer 1:observer 2), and the mean difference was -3 mm2 (95% confidence interval [CI] of the difference -5.4-1.46 mm2). The maximum cross-sectional area of the reference artery was 26:28 mm2 (observer 1:observer 2), and the mean difference was -2 mm2 (95% CI -5.7-1.2 mm2). Neither difference was significant. Intraobserver reliability also was good. The measurement of intracranial aneurysm and artery size with power TCD is reliable sufficiently for use in longitudinal studies of changes in aneurysm size.

A test of the stability of Cd, Cu, Hg, Pb and Zn profiles over two decades in lake sediments near the Flin Flon Smelter, Manitoba, Canada.

Lake sediments are valuable archives of atmospheric metal deposition, but the stability of some element profiles may possibly be affected by diagenetic changes over time. In this extensive case study, the stability of sedimentary Cd, Cu, Hg, Pb and Zn profiles was assessed in dated sediment cores that were collected in 2004 from four smelter-affected lakes near Flin Flon, Manitoba, which had previously been cored in 1985. Metal profiles determined in 1985 were in most cases clearly reproduced in the corresponding sediment layers in 2004, although small-scale spatial heterogeneity in metal distribution complicated the temporal comparisons. Pre-smelter (i.e. pre-1930) increases in metal profiles were likely the result of long-range atmospheric metal pollution, coupled with particle mixing at the 1930s sediment surface. However, the close agreement between key inflection points in the metal profiles sampled two decades apart suggests that metals in most of the lakes, and Hg and Zn in the most contaminated lake (Meridian), were stable once the sediments were buried below the surface mixed layer. Cadmium, Cu and Pb profiles in Meridian Lake did not agree as well between studies, showing evidence of upward remobilization over time. Profiles of redox-indicator elements (Fe, Mn, Mo and U) suggested that the rate of Mn oxyhydroxide recycling within sediment was more rapid in Meridian Lake, which may have caused the Cd, Cu and Pb redistribution.

Comparison of mercury and zinc profiles in peat and lake sediment archives with historical changes in emissions from the Flin Flon metal smelter, Manitoba, Canada.

The copper-zinc smelter at Flin Flon, Manitoba, was historically the largest single Hg point-source in Canada, as well as a major source of Zn. Although emissions were reported by industry to have declined significantly since the late 1980s, these reductions have never been independently verified. Here, the histories of Hg and Zn deposition over the past century or more were determined at five lake sediment and three peat study sites in the surrounding region. At sites spanning the range from heavy to minor pollution, lake sediment Hg and Zn concentration and flux profiles increased significantly in the early 1930s after the smelter opened. Two of the three peat archives were wholly or partially compromised by either physical disturbances or biogeochemical transitions which reduced their effectiveness as atmospheric metal deposition recorders. But the remaining peat records, including a detailed recent 20 yr record at a moderately polluted site, appeared to show that substantive reductions in metal levels had occurred after the late 1980s, coincident with the reported emission reductions. However, the lake sediment results, taken at face value, contradicted the peat results in that no major declines in metal concentrations or fluxes occurred over recent decades. Mercury and Zn fluxes have in fact increased substantially since 1988 in most lakes. We suggest that this discrepancy may be explained by catchment soil saturation by historically deposited metals which are now mobilizing and leaching into lakes, as has been reported from other smelter polluted systems in Canada, whereas the upper sections of the peat cores reflected recent declines in atmospheric deposition. However, further research including instrumented wet and dry deposition measurements and catchment/lake mass balance studies is recommended to test this hypothesis, and to provide definitive data on current atmospheric metal deposition rates in the area.