Comparison of PDMS and NOA Microfluidic Chips: Deformation, Roughness, Hydrophilicity and Flow Performance.

Microfluidic devices are frequently manufactured with polydimethylsiloxane (PDMS) due to its affordability, transparency, and simplicity. However, high-pressure flow through PDMS microfluidic channels lead to an increase in channel size due to the compliance of the material. As a result, longer response times are required to reach steady flow rates, which increases the overall time required to complete experiments when using a syringe pump. Due to its excellent optical properties and increased rigidity, Norland Optical Adhesive (NOA) has been proposed as a promising material candidate for microfluidic fabrication. This study compares the compliance and deformation properties of three different characteristic sized (width of parallel channels: 100, 40 and 20 µm) microfluidic devices made of PDMS and NOA. The comparison of the microfluidics devices is made based on the Young's modulus, roughness, contact angle, channel width deformation, flow resistance and compliance. The experimental resistance is estimated through the measurement of the flow at a given pressure and a precision flow meter. The characteristic time of the system is extracted by fitting the two-element resistance-compliance (RC) hydraulic circuit model. The compliance of the microfluidics chips is estimated through the measurement of the characteristic time required for channels to achieve an output flow rate equivalent to that of the input flow rate using a syringe pump and a precision flow meter. The Young modulus was found to be 2 MPa for the PDMS and 1743 MPa for the NOA 63. The surface roughness was found to be higher for the NOA 63 than for the PDMS. The hydrophilicities of materials were found comparable with and without plasma treatment. The results show that NOA devices have lower compliance and deformation than PDMS devices.

Residents' Perceptions of a Novel Virtual Livestream Cadaveric Teaching Series for Musculoskeletal Anatomy Education.

ABSTRACT: Musculoskeletal anatomy education is essential to many healthcare providers but has consistently been considered difficult for various reasons. Traditional methods have focused on in-person cadaveric teaching, which became inaccessible during the COVID-19 pandemic; therefore, new teaching methods were developed to address this gap in education. This project implemented novel virtual livestream musculoskeletal anatomy teaching methodology with cadaveric prosections and evaluated the efficacy of this modality compared with traditional in-person cadaveric teaching. A targeted musculoskeletal anatomy curriculum was developed and delivered via livestream to 12 Canadian physiatry residents. Upon completing the virtual curriculum, residents completed an anonymous survey assessing this new virtual livestream cadaveric methodology compared with previous experiences with traditional in-person anatomy teaching. The survey response rate was 92%. Most participants (73%) rated the virtual livestream sessions as better than traditional in-person teaching. Reasons included better visualization of cadaveric anatomy and easy discussion among the group. T test analysis comparing both methods demonstrated the livestream method was equivalent or better across several domains. Virtual livestream teaching is a viable method for teaching the important subject of musculoskeletal anatomy. Educators should consider how to best integrate this approach into future anatomy curricula.

Micro-particle image velocimetry for blood flow in thick round glass micro-channels: Channel fabrication and velocity profile characterization.

This method describes the use of thick round borosilicate glass micro-channels for blood flow visualization using micro-particle image velocimetry (µPIV) techniques. In contrast with popular methods using squared polydimethylsiloxane channels, this method allows for visualization of blood flow in channel geometries that resemble more the natural physiology of human blood vessels. With a custom designed enclosure, the microchannels were submerged in glycerol to reduce light refraction occurring during µPIV due to the thick walls of the glass channels. A method is proposed to correct the extracted velocity profiles from the µPIV to account for out-of-focus error. The customized elements of this method include: • The use of thick circular glass micro-channels, • a custom designed mounting solution for the channels on a glass slide for flow visualization, • a MATLAB code to correct velocity profile accounting for out-of-focus error.

Semi-automated red blood cell core detection in blood micro-flow.

In microcirculation, red blood cells (RBCs) tend to migrate toward the centre of the vessel leaving a region of a cell depleted layer or cell-free layer (CFL) at the vessel wall and a core of RBCs at the centre. This heterogenous distribution of cells has an effect on the blood apparent viscosity and the exchanges of gases and nutrients between the RBCs and the vessel. Understanding the formation of the CFL and obtaining accurate measurement of it is paramount for furthering development of devices such as drug administration. This paper presents a general semi-automatic method to quantify the thickness of the CFL for different channel geometries and image quality. It enables the use of a method based on intensity, a method using the gradient of the intensity, or a method based on spatiotemporal variation. The main features are reported, the performance is demonstrated on experimentally obtained image sets and accuracy is validated using synthetic images with known CFL thickness. A pure automatic detection is limited by the most visually correct using the spatiotemporal method, however proposed thresholding through automatic detection allows for quality controls through manual adjustments. With a semi-automatic approach RBC core variability between 3 % to 8 % was found when the test user was tasked with repeating the analysis of the same set. The presented method provides, users without programming ability with a user-friendly interface that can extract CFL automatically with quality control through manual adjustments.

Image-Based Experimental Measurement Techniques to Characterize Velocity Fields in Blood Microflows.

Predicting blood microflow in both simple and complex geometries is challenging because of the composition and behavior of the blood at microscale. However, characterization of the velocity in microchannels is the key for gaining insights into cellular interactions at the microscale, mechanisms of diseases, and efficacy of therapeutic solutions. Image-based measurement techniques are a subset of methods for measuring the local flow velocity that typically utilize tracer particles for flow visualization. In the most basic form, a high-speed camera and microscope setup are the only requirements for data acquisition; however, the development of image processing algorithms and equipment has made current image-based techniques more sophisticated. This mini review aims to provide a succinct and accessible overview of image-based experimental measurement techniques to characterize the velocity field of blood microflow. The following techniques are introduced: cell tracking velocimetry, kymographs, micro-particle velocimetry, and dual-slit photometry as entry techniques for measuring various velocity fields either in vivo or in vitro.

Deletion of Oncomodulin Gives Rise to Early Progressive Cochlear Dysfunction in C57 and CBA Mice.

Ca2+ signaling is a major contributor to sensory hair cell function in the cochlea. Oncomodulin (OCM) is a Ca2+ binding protein (CaBP) preferentially expressed in outer hair cells (OHCs) of the cochlea and few other specialized cell types. Here, we expand on our previous reports and show that OCM delays hearing loss in mice of two different genetic backgrounds: CBA/CaJ and C57Bl/6J. In both backgrounds, genetic disruption of Ocm leads to early progressive hearing loss as measured by auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE). In both strains, loss of Ocm reduced hearing across lifetime (hearing span) by more than 50% relative to wild type (WT). Even though the two WT strains have very different hearing spans, OCM plays a considerable and similar role within their genetic environment to regulate hearing function. The accelerated age-related hearing loss (ARHL) of the Ocm KO illustrates the importance of Ca2+ signaling in maintaining hearing health. Manipulation of OCM and Ca2+ signaling may reveal important clues to the systems of function/dysfunction that lead to ARHL.

The genome of the crustacean Parhyale hawaiensis, a model for animal development, regeneration, immunity and lignocellulose digestion.

The amphipod crustacean Parhyale hawaiensis is a blossoming model system for studies of developmental mechanisms and more recently regeneration. We have sequenced the genome allowing annotation of all key signaling pathways, transcription factors, and non-coding RNAs that will enhance ongoing functional studies. Parhyale is a member of the Malacostraca clade, which includes crustacean food crop species. We analysed the immunity related genes of Parhyale as an important comparative system for these species, where immunity related aquaculture problems have increased as farming has intensified. We also find that Parhyale and other species within Multicrustacea contain the enzyme sets necessary to perform lignocellulose digestion ('wood eating'), suggesting this ability may predate the diversification of this lineage. Our data provide an essential resource for further development of Parhyale as an experimental model. The first malacostracan genome will underpin ongoing comparative work in food crop species and research investigating lignocellulose as an energy source.

Evaluation of a mobile X-ray service for elderly residents of residential aged care facilities.

OBJECTIVE: The Royal Melbourne Hospital established a mobile X-ray service (MXS) in 2013. The goal of the MXS is to address the radiology needs of frail, elderly or demented residents of residential aged care facilities (RACFs) who would otherwise require transportation to attend for X-ray. The present study describes the activity of the MXS, and the impact of the MXS on emergency department (ED) attendances by residents of RACFs. METHODS: The study is a descriptive study and uses a before-and-after cohort approach. Activity for the first year of operation was collected and described. At the end of the first year of operation, the top 30 RACF users of the MXS were identified. The hospital Department of Radiology database was examined to find all plain X-rays performed on any patient presenting from the same 30 RACFs for the 1 year before commencement of the MXS (1 July 2012-30 June 2013) and for the 1 year period after the commencement of the MXS (1 July 2013-30 June 2014). Attendances were compared. RESULTS: The MXS delivered 1532 service attendances to 109 different RACFs. The mean age of patients receiving MXS services was 86 years (range 16-107 years). In all, 1124 services (73.4%) were delivered to patients in high-care RACFs. Most patients (n = 634; 41.4%) were bed or wheelchair bound, followed by those who required assistance to ambulate (n = 457; 29.8%). The most common X-ray examinations performed were chest, hip and pelvis, spine and abdomen. There were 919 service attendances to the top 30 RACFs using the MXS (60.0% of all attendances). There was an 11.5% reduction in ED presentations requiring plain X-ray in the year following the commencement of the MXS (95% confidence interval 0.62-3.98; P = 0.019). CONCLUSION: The present study suggests a reduction in hospital ED attendances for high users of the MXS. This has benefits for hospitals, patients and nursing homes. It also allows the extension of other programs designed to treat patients in their RACFs. Special rebates for home-based radiology service provision should be considered.

Detection of Blastocystis from stool samples using real-time PCR.

We developed a real-time LC PCR assay to detect a 152 bp sequence in an uncharacterized region of the Blastocystis genome. The described assay detected 11 of 11 ATCC strains of Blastocystis from subtypes 1, 3, and 4. Three of three stool samples from Oregon and California military personnel that were negative for Blastocystis by an ova and parasite test as well as a conventional PCR assay were positive for Blastocystis using our real-time LC PCR assay. Diagnosis of Blastocystis infections using this sensitive method, including DNA extraction and real-time PCR, only requires 3 h. The lower limit of detection for Blastocystis in stool using the real-time LC PCR assay was calculated to be 760 cells of Blastocystis per 100 mg of stool, an estimated 760 parasites per reaction. The assay did not cross-react with Ruminococcus hansenii, Anarococcus hydrogenalis, Bifidobacterium adolescentis, Fusobacterium prausnitzii, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, or Lactobacillus acidophilus. Because of the ease of use, sensitivity, specificity, and increase in Blastocystis infections in the USA we believe this assay has the potential to be useful as a clinical diagnosis tool of Blastocystis infection.