Flow Chamber for Confocal Tracking of Particles in Bone

Interstitial fluid flow in the lacunar-canalicular system (LCS) of bone is recognized as a potential regulator of bone remodeling. Movement of fluid across bone cells called osteocytes regulates gene expression that leads to either bone formation or resorption. Interstitial fluid moves in response to bone loading during daily activity, and bone growth occurs to compensate for these loads, affecting bone shape and strength. While interstitial fluid flow is thoroughly studied using computational models, there is a critical need to study flow in real bone samples with imaging techniques. Flow velocities determined from imaging will be more accurate than computational models due to the simplifying assumptions that are made when building a model. This study presents a sealed system that allows for imaging of particle flow in bone using confocal microscopy. The flow apparatus was designed in Autodesk Fusion 360 and fluid flow was controlled using an electric constant flow pump. For comparison with experimental data, a computational model based on confocal microscopy images was created to calculate flow velocities in the LCS using ANSYS Fluent. The results of this study will develop a novel method for tracking interstitial fluid flow in the LCS, providing a new strategy to study how fluid flow affects bone remodeling. The ability to measure fluid flow in bone allows for the connection of age or disease related alterations in the LCS to changes in bone mass and structure

The Role of Osteocyte Estrogen Receptor Beta (ERβ) in Regulating the Skeletal Response to Mechanical Loading

Estrogen’s biological functions are mediated by estrogen binding to estrogen receptors (ER). Understanding what role both ERα and ERβ have in bone maintenance and formation can contribute to possible treatment of osteoporosis. This study examined osteocyte specific deletion of ERβ in mice. The cross of ERβ-floxed mice with DMP1-8kb-Cre mice provided both experimental knockout mice as well as littermate control mice. At 24 weeks of age the left tibiae of all mice were mechanically loaded five days per week for two weeks to induce bone formation. Analysis of cortical bone was conducted using microcomputed tomography (microCT) to measure load-induced changes in bone density and architecture of both loaded and non-loaded limbs. We found a significant effect of load on cortical bone geometry in both male and female knockout and control mice at 37% and 50% bone length. Based on our findings, osteocyte ERβ appears to play a minor role in determining cortical bone geometry in 24 week old mice. We are still investigating the effect of load and genotype on cancellous bone

Optimization of Imaging Parameters to Determine Flow Velocity Using Nanoparticles

Microfluidic flow chambers have been developed and used to measure flow at the microscopic level. Nanoparticles can be used to track the fluid flow within the chamber and this allows for accurate velocity measures. Microscope parameters used for experimentation differ across various projects and resources; therefore, there is a need to determine the best combination of settings for the equipment at hand. Once appropriate settings are selected, images of the flow are captured with a confocal microscope and can be analyzed using custom written MATLAB code. A pair cross-correlation function is used to determine where the particles have traveled in the flow as a function of time. Pair correlation has proven to surpass the limitations of other techniques such as fluorescent recovery after photo-bleaching and single particle tracking. A proper protocol for microfluidic nanoparticle imaging and analysis is now developed to be used for future applications that utilize the same particles and confocal microscope

In situ single-crystal X-ray diffraction studies of physisorption and chemisorption of SO2 within a metal-organic framework and its competitive adsorption with water

Funding: The authors are also grateful for financial assistancefrom the ERC under advanced grant 787073, the EPSRC for a studentship (EP/N509759/1) and support via the Collaborative Computational Projecton NMR Crystallography CCP-NC (EP/T02662/1), and the CRITICAT Centre for Doctoral Training (EP/L016419/1).Living on an increasingly polluted planet, the removal of toxic pollutants such as sulfur dioxide (SO2) from the troposphere and power station flue gas is becoming more and more important. The CPO-27/MOF-74 family of metal–organic frameworks (MOFs) with their high densities of open metal sites is well suited for the selective adsorption of gases that, like SO2, bind well to metals and have been extensively researched both practically and through computer simulations. However, until now, focus has centered upon the binding of SO2 to the open metal sites in this MOF (called chemisorption, where the adsorbent–adsorbate interaction is through a chemical bond). The possibility of physisorption (where the adsorbent–adsorbate interaction is only through weak intermolecular forces) has not been identified experimentally. This work presents an in situ single-crystal X-ray diffraction (scXRD) study that identifies discrete adsorption sites within Ni-MOF-74/Ni-CPO-27, where SO2 is both chemisorbed and physisorbed while also probing competitive adsorption of SO2 of these sites when water is present. Further features of this site have been confirmed by variable SO2 pressure scXRD studies, DFT calculations, and IR studies.Publisher PDFPeer reviewe

L-band synthetic aperture radar imagery performs better than optical datasets at retrieving woody fractional cover in deciduous, dry savannahs

Woody canopy cover (CC) is the simplesttwo dimensional metric for assessing the presence ofthe woody component in savannahs, but detailed validated maps are not currently available in southern African savannahs. A number of international EO programs (including in savannah landscapes) advocate and use optical LandSAT imagery for regional to country-wide mapping of woody canopy cover. However, previous research has shown that L-band Synthetic Aperture Radar (SAR) provides good performance at retrieving woody canopy cover in southern African savannahs. This study’s objective was to evaluate, compare and use in combination L-band ALOS PALSAR and LandSAT-5 TM, in a Random Forest environment, to assess the benefits of using LandSAT compared to ALOS PALSAR. Additional objectives saw the testing of LandSAT-5 image seasonality, spectral vegetation indices and image textures for improved CC modelling. Results showed that LandSAT-5 imagery acquired in the summer and autumn seasons yielded the highest single season modelling accuracies (R2 between 0.47 and 0.65), depending on the year but the combination of multi-seasonal images yielded higher accuracies (R2 between 0.57 and 0.72). The derivation of spectral vegetation indices and image textures and their combinations with optical reflectance bands provided minimal improvement with no optical-only result exceeding the winter SAR L-band backscatter alone results (R2 of ∼0.8). The integration of seasonally appropriate LandSAT-5 image reflectance and L-band HH and HV backscatter data does provide a significant improvement for CC modelling at the higher end of the model performance (R2 between 0.83 and 0.88), but we conclude that L-band only based CC modelling be recommended for South African regionshttp://www.elsevier.com/locate/jag2017-10-31hb2016Geography, Geoinformatics and Meteorolog