Diffusion Coefficients and Viscosities of CO2 + H2O, CO2 + CH3OH, NH3 + H2O, and NH3 + CH3OH Liquid Mixtures

To evaluate quantitatively the results of gas-liquid absorption experiments, accurate liquid-phase diffusion coefficients and viscosities are needed. In this paper experimental values of these quantities will be reported for the binary systems carbon dioxide + water, carbon dioxide + methanol, ammonia + water, and ammonia + methanol. The diffusion coefficients have been measured using the Taylor-Aris dispersion method, and the viscosities have been measured with a falling ball viscometer at temperatures from 293 to 333 K. The ammonia mole fraction ranged from 0 to 0.312. The results have been correlated using Arrhenius-type equations and have been compared with literature data, where available. Furthermore, the measured diffusion coefficients are compared with values predicted by the modified Stokes-Einstein equation and the Wilke-Chang equation

Prediction and analysis of long-term variability of temperature and salinity in the Irish Sea

The variability of temperature and salinity in the Irish Sea over the 40 year period 1960 - 1999 is investigated using a free-running fine-resolution local area model. The skill of the model to represent observed temperature and salinity variability is assessed using conductivity-temperature-depth survey data ( 3397 profiles) and a long time series of measurements from Cypris station (southwest of Isle of Man). This clearly demonstrates that the model can reproduce the observed seasonal and longer-term cycles in temperature, with mean and RMS errors of - 0.01 degrees C and 0.78 degrees C. Particularly apparent is the long-term warming trend at Cypris station and throughout the model domain. Model estimates of salinity are less accurate and are generally too saline (mean and RMS errors are 0.79 and 0.98 practical salinity units). Inaccuracies are likely to arise from boundary conditions and forcing (riverine and surface). However, while absolute values are not particularly well represented, the model reproduces many of the trends in the salinity variability observed at Cypris station, suggesting that the dominant physical processes in the Irish Sea, with timescales up to similar to 3 years, are well represented. The model is also used to investigate the variability in temperature stratification. While stratification is confined to approximately the same geographical area in each year of the simulation, there is significant variability in the timing of the onset and breakdown of stratification and in the peak surface to bed temperature difference. Together, these results suggest that a local area model with limited boundary conditions may be sufficiently accurate for climatic investigation of some (locally forced) parameter

A solution NMR approach to determine the chemical structures of carbohydrates using the hydroxyl groups as starting points

An efficient NMR approach is described for determining the chemical structures of the monosaccharide glucose and four disaccharides, namely, nigerose, gentiobiose, leucrose and isomaltulose. This approach uses the 1H resonances of the −OH groups, which are observable in the NMR spectrum of a supercooled aqueous solution, as the starting point for further analysis. The 2D-NMR technique, HSQC-TOCSY, is then applied to fully define the covalent structure (i.e., the topological relationship between C–C, C–H, and O–H bonds) that must be established for a novel carbohydrate before proceeding to further conformational studies. This process also leads to complete assignment of all 1H and 13C resonances. The approach is exemplified by analyzing the monosaccharide glucose, which is treated as if it were an “unknown”, and also by fully assigning all the NMR resonances for the four disaccharides that contain glucose. It is proposed that this technique should be equally applicable to the determination of chemical structures for larger carbohydrates of unknown composition, including those that are only available in limited quantities from biological studies. The advantages of commencing the structure elucidation of a carbohydrate at the −OH groups are discussed with reference to the now well-established 2D-/3D-NMR strategy for investigation of peptides/proteins, which employs the −NH resonances as the starting point

Animal community dynamics at senescent and active vents at the 9° N East Pacific Rise after a volcanic eruption

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gollner, S., Govenar, B., Arbizu, P. M., Mullineaux, L. S., Mills, S., Le Bris, N., Weinbauer, M., Shank, T. M., & Bright, M. Animal community dynamics at senescent and active vents at the 9° N East Pacific Rise after a volcanic eruption. Frontiers in Marine Science, 6, (2020): 832, doi:10.3389/fmars.2019.00832.In 2005/2006, a major volcanic eruption buried faunal communities over a large area of the 9°N East Pacific Rise (EPR) vent field. In late 2006, we initiated colonization studies at several types of post eruption vent communities including those that either survived the eruption, re-established after the eruption, or arisen at new sites. Some of these vents were active whereas others appeared senescent. Although the spatial scale of non-paved (surviving) vent communities was small (several m2 compared to several km2 of total paved area), the remnant individuals at surviving active and senescent vent sites may be important for recolonization. A total of 46 meio- and macrofauna species were encountered at non-paved areas with 33 of those species detected were also present at new sites in 2006. The animals living at non-paved areas represent refuge populations that could act as source populations for new vent sites directly after disturbance. Remnants may be especially important for the meiofauna, where many taxa have limited or no larval dispersal. Meiofauna may reach new vent sites predominantly via migration from local refuge areas, where a reproductive and abundant meiofauna is thriving. These findings are important to consider in any potential future deep-sea mining scenario at deep-sea hydrothermal vents. Within our 4-year study period, we regularly observed vent habitats with tubeworm assemblages that became senescent and died, as vent fluid emissions locally stopped at patches within active vent sites. Senescent vents harbored a species rich mix of typical vent species as well as rare yet undescribed species. The senescent vents contributed significantly to diversity at the 9°N EPR with 55 macrofaunal species (11 singletons) and 74 meiofaunal species (19 singletons). Of these 129 species associated with senescent vents, 60 have not been reported from active vents. Tubeworms and other vent megafauna not only act as foundation species when alive but provide habitat also when dead, sustaining abundant and diverse small sized fauna.We received funding from the Austrian FWF (GrantP20190-B17; MB), the U.S. National Science Foundation (OCE-0424953; to LM, D. McGillicuddy, A. Thurnherr, J. Ledwell, and W. Lavelle; and OCE-1356738 to LM), and the European Union Seventh Framework Programme (FP7/2007-2013) under the MIDAS project, Grant Agreement No. 603418. Ifremer and CNRS (France) supported NL cruise participation and sensor developments. BG was supported by a postdoctoral fellowship from the Deep Ocean Exploration Institute at WHOI (United States). TS was supported by the U.S. National Science Foundation (OCE-0327261 to TS and OCE-0937395 to TS and BG)

Using Strontium Coated Clay Nanoparticles For Bone Regeneration And Other Biomedical Applications

The aim of this project is to coat halloysite nanotubes (HNTs) with strontium in an ecofriendly, simple, and non-expensive process. These particles, when doped in calcium phosphate cements (CPC), are predicted to increase the osteoconductive and antibacterial properties of three dimensional (3D) printed bone scaffolds. The purpose of the 3D printed bone scaffolds is to assume the same function as the bones they are replacing but with several additional functionalities. These biomaterials will have the ability to be resorbed as new bone is formed. Due to inherent osteogenic factors and antibiotics released from doped HNTs during the reparative process, it will also provide surgeons with a multi-functional construct for a diverse set of dental and orthopedic applications. The purpose of the 3D printed scaffolds will be to provide a microenvironment for normal cells along with the ability to release antimicrobial, chemotherapeutics or other drugs. The system will also enable growth factor release. Material characterization was conducted to confirm the presence of Sr on the HNTs. Cellular characterizations studies assessed cellular impact and behavior and included cytocompatibility studies, osteogenic/osteoinductive, and differentiation effects on pre-osteoblast cells and stromal cells. Material characterization studies included material strength test of the SrHNT/CPC composites. Based on the results, fabrication methods in future will be modified as needed to obtain the ideal medical construct

Nano clay-enhanced calcium phosphate cements and hydrogels for biomedical applications

Biomaterials are used as templates for drug delivery, scaffolds in tissue engineering, grafts in surgeries, and support for tissue regeneration. Novel biomaterial composites are needed to meet multifaceted requirements of compatibility, ease of fabrication and controlled drug delivery. Currently used biomaterials in orthopedics surgeries suffer limitations in toxicity and preventing infections. Polymethyl methacrylate (PMMA) used as bone cement suffers from limitations of thermal necrosis and monomer toxicity calls for development of better cementing biomaterials. A biodegradable/bioresorbable cement with good mechanical properties is needed to address this short coming. Metal implants used in fixing fractures or total joint replacement needs improvements in preventing biofilm formation and better tissue integration. This research addressed the above mentioned research gaps by formulating novel biomaterial composites. Calcium phosphate cements are the alternative bone cements that are bioresorbable and promote tissue integration. These cements lack sufficient mechanical strengths to be used in load bearing sites. The addition of nanoparticles is hypothesized to improve the mechanical properties without inducing toxicity to the tissue. This hypothesis was tested by evaluating compression and flexural strengths in addition to cytocompatibility tests. Results indicate that addition of nano-clay particles (halloysites nanotubes) improved the compressive strength and osteoinductive properties of calcium phosphate cements. To address the research need of preventing implant failure due to infection and aseptic loosening, novel coatings are needed. Hydrogels are well establish for their ability to mimic in vivo environment, promote cell viability and as drug delivery vehicles. Use of composites of hydrogels and drug-loaded nanoparticles to prevent infection was evaluated. Cytocompatibility results indicate good cell viability. Antibacterial results show sustained release of antibiotics from composite hydrogels and good zones of inhibition on agar plates inoculated with bacterial cultures. Fabricating a complex three-dimensional (3D) scaffold for tissue engineering was a huge challenge. With advancements in additive manufacturing, this research gap was addressed. Methods are needed to fabricate patient specific grafts made from biocompatible biomaterials. In this research, 3D printing was used as a platform to explore new biomaterials as grafts or scaffolds for tissue engineering. Computerized tomography scans were used to fabricate patient-specific grafts. The use of calcium cements to fabricate three-dimensionally complex scaffold or grafts reported in this research holds potential in personalized medicine

Virginia Academy of Science 1999 Best Student Paper Awards

List of award winning student papers by section from the Virginia Academy of Science, 199

Challenges of achieving good environmental status in the Northeast Atlantic

The sustainable exploitation of marine ecosystem services is dependent on achieving and maintaining an adequate ecosystem state to prevent undue deterioration. Within the European Union, the Marine Strategy Framework Directive (MSFD) requires member states to achieve Good Environmental Status (GEnS), specified in terms of 11 descriptors. We analyzed the complexity of social-ecological factors to identify common critical issues that are likely to influence the achievement of GEnS in the Northeast Atlantic (NEA) more broadly, using three case studies. A conceptual model developed using a soft systems approach highlights the complexity of social and ecological phenomena that influence, and are likely to continue to influence, the state of ecosystems in the NEA. The development of the conceptual model raised four issues that complicate the implementation of the MSFD, the majority of which arose in the Pressures and State sections of the model: variability in the system, cumulative effects, ecosystem resilience, and conflicting policy targets. The achievement of GEnS targets for the marine environment requires the recognition and negotiation of trade-offs across a broad policy landscape involving a wide variety of stakeholders in the public and private sectors. Furthermore, potential cumulative effects may introduce uncertainty, particularly in selecting appropriate management measures. There also are endogenous pressures that society cannot control. This uncertainty is even more obvious when variability within the system, e.g., climate change, is accounted for. Also, questions related to the resilience of the affected ecosystem to specific pressures must be raised, despite a lack of current knowledge. Achieving good management and reaching GEnS require multidisciplinary assessments. The soft systems approach provides one mechanism for bringing multidisciplinary information together to look at the problems in a different light

Growth and behavior of chondrocytes on nano engineered surfaces and construction of micropatterned co-culture platforms using layer-by-layer platforms using layer -by -layer assembly lift-off method

Several approaches such as self-assembled monolayers and layer-by-layer assembled multilayer films are being used as tools to study the interactions of cells with biomaterials in vitro. In this study, the layer-by-layer assembly approach was used to create monolayer, bilayer, trilayer, five, ten and twenty-bilayer beds of eleven different biomaterials. The various biomaterials used were poly(styrene-sulfonate), fibronectin, poly-L-lysine, poly-D-lysine, laminin, bovine serum albumin, chondroitin sulfate, poly(ethyleneimine), polyethylene glycol amine, collagen and poly(dimethyldiallyl-ammonium chloride) with unmodified tissue-culture polystyrene as standard control. Three different cell lines—primary bovine articular chondrocytes, and two secondary cell lines, human chondrosarcoma cells and canine chondrocytes were used in these studies. Chondrocyte morphology and attachment, viability, proliferation, and functionality were determined using bright field microscopy, the Live/Dead viability assay, MTT assay, and immunocytochemistry, respectively. Atomic force microscopy of the nanofilms indicated an increase in surface roughness with increasing number of layers. The most important observations from the studies on primary bovine articular chondrocytes were that these cells exhibited increasing viability and cell metabolic activity with increasing number of bilayers. The increase in viability was more pronounced than the increase in cell metabolic activity. Also, bovine chondrocytes on bilayers of poly(dimethyldiallyl-ammonium chloride, poly-L-lysine, poly(styrene-sulfonate), and bovine serum albumin were substantially bigger in size and well-attached when compared to the cells grown on monolayer and trilayers. Lactate dehydrogenase assay performed on chondrosarcoma cells grown on 5- and 10-bilayer multilayer beds indicated that the 10-bilayer beds had reduced cytotoxicity compared to the 5-bilayer beds. MTT assay performed on canine chondrocytes grown on 5-, 10-, and 20-bilayer nanofilm beds revealed increasing cell metabolic activity for BSA with increasing bilayers. Micropatterned multilayer beds having poly-L-lysine, poly-D-lysine, laminin poly(dimethyldiallyl-ammonium chloride) and poly(ethyleneimine) as the terminating layers were fabricated using the Layer-by-layer Lift-off (LbL-LO) method that combines photolithography and LbL self-assembly. Most importantly, micropatterned co-culture platforms consisting of anti-CD 44 rat monoclonal and anti-rat osteopontin (MPIIIB101) antibodies were constructed using the LbL-LO method for the first time. These co-culture platforms have several applications especially for studies of stem and progenitor cells. Co-culture platforms exhibiting spatiotempora-based differentiation can be built with LbL-LO for the differentiation of stem cells into the desired cell lineage

Derivation of the specific optical properties of suspended mineral particles and their contribution to the attenuation of solar irradiance in offshore waters by ocean color remote sensing

Two independently derived algorithms which had previously been validated against in situ data were applied to 8 years of MODIS observations of the Irish Sea to obtain (i) concentrations of lithogenic mineral particles (MSSl) in surface waters and (ii) the specific backscattering and absorption coefficients for these particles in the 488 nm waveband (the values obtained were a*MSSl488=0.031 m2 g-1 and bb*MSSl488=0.010 m2 g-1). This information was used to calculate the mean attenuation coefficient for downward irradiance K-d(488) in the surface mixed layer, and the fraction of this coefficient that was attributable to suspended mineral particles. Mineral particles at relatively low concentrations (<5 g m-3) were the major determinant of K-d(488) values throughout the region in winter, and in the central Irish Sea this influence persisted for much of the spring/autumn primary production period. In the north and south, however, marked short-term increases in K-d(488) due to phytoplankton blooms occurred during periods when MSSl values were relatively low. Seasonally averaged maps of the fractional contribution of MSSl to K-d(488) show strong links to vertical mixing, with sharp contrasts developing in spring at the boundaries between mixed and stratified waters. We conclude that the ocean color processing sequence presented here can reveal spatial and seasonal patterns in the dynamics of lithogenic mineral particles which have potentially valuable applications in ecosystem status assessment, environmental impact monitoring, and the tuning and validation of numerical models of shelf sea ecosystems