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3D printing has been shown to be a robust and inexpensive manufacturing tool for a range of applications within biomedical science. Here we report the design and fabrication of a 3D printer-enabled microfluidic device used to generate cell-laden hydrogel microspheres of tunable sizes. An inverse mold was printed using a 3D printer, and replica molding was used to fabricate a PDMS microfluidic device. Intersecting channel geometry was used to generate perfluorodecalin oil-coated gelatin methacrylate (GelMA) microspheres of varying sizes (35–250 μm diameters). Process parameters such as viscosity profile and UV cross-linking times were determined for a range of GelMA concentrations (7–15% w/v). Empirical relationships between flow rates of GelMA and oil phases, microspheres size, and associated swelling properties were determined. For cell experiments, GelMA was mixed with human osteosarcoma Saos-2 cells, to generate cell-laden GelMA microspheres with high long-term viability. This simple, inexpensive method does not require the use of traditional cleanroom facilities and when combined with the appropriate flow setup is robust enough to yield tunable cell-laden hydrogel microspheres for potential tissue engineering applications.
Reports in the literature of treatment with recombinant tissue plasminogen activator following cardiac surgery are limited. We reviewed our experience to provide a case series of the therapeutic use of tissue plasminogen activator for the treatment of venous thrombosis in children after cardiac surgery. The data describe the morbidity, mortality, and clinical outcomes of tissue plasminogen activator administration for treatment of venous thrombosis in children following cardiac surgery.
The study was designed as a retrospective case series.
The study was carried out in a 25-bed cardiac intensive care unit in an academic, free-standing paediatric hospital.
All children who received tissue plasminogen activator for venous thrombosis within 60 days of cardiac surgery, a total of 13 patients, were included.
Data was collected, collated, and analysed as a part of the interventions of this study.
Measurements and main results
Patients treated with tissue plasminogen activator were principally young infants (median 0.2, IQR 0.07–0.58 years) who had recently (22, IQR 12.5–27.3 days) undergone cardiac surgery. Hospital mortality was high in this patient group (38%), but there was no mortality attributable to tissue plasminogen activator administration, occurring within <72 hours. There was one major haemorrhagic complication that may be attributable to tissue plasminogen activator. Complete or partial resolution of venous thrombosis was confirmed using imaging in 10 of 13 patients (77%), and tissue plasminogen activator administration was associated with resolution of chylous drainage, with no drainage through chest tubes, at 10 days after tissue plasminogen activator treatment in seven of nine patients who had upper-compartment venous thrombosis-associated chylothorax.
On the basis of our experience with administration of tissue plasminogen activator in children after cardiac surgery, tissue plasminogen activator is both safe and effective for resolution of venous thrombosis in this high-risk population.
Three-dimensional (3D) printing has expanded beyond the mere patterned deposition of melted solids, moving into areas requiring spatially structured soft matter—typically materials composed of polymers, colloids, surfactants, or living cells. The tunable and dynamically variable rheological properties of soft matter enable the high-resolution manufacture of soft structures. These rheological properties are leveraged in 3D printing techniques that employ sacrificial inks and sacrificial support materials, which go through reversible solid–fluid transitions under modest forces or other small perturbations. Thus, a sacrificial material can be used to shape a second material into a complex 3D structure, and then discarded. Here, we review the sacrificial materials and related methods used to print soft structures. We analyze data from the literature to establish manufacturing principles of soft matter printing, and we explore printing performance within the context of instabilities controlled by the rheology of soft matter materials.
Le postulat de cette chronique est qu’il reste encore une grande vitalité au cadre nationalà l’ère de l’histoire globale et impériale. On peut lire les trois volumes de l’Histoire de la France contemporaine par Aurélien Lignereux, Bertrand Goujon et Quentin Deluermozcomme une nouvelle vague dans un projet historiographique qui cherche à se renouveler: comment empêcher ce retour au national de n’être qu’un voyage nostalgique, n’ayant rien perdu de son charme et de son attrait populaire, mais qui semble mis à mal par des échelles historiographiques plus vastes ? En effet, les modalités radicalement neuves selon lesquelles s’imbriquèrent si profondément les échelles locale, régionale, impériale, océanique, hémi-sphérique et globale au cours du XIXe siècle résultèrent en partie de la construction et de la consolidation de l’État-nation moderne. Il est donc nécessaire, et c’est précisément ce qu’une lecture (qui est tout autant une interprétation) de ces volumes suggère, non pas de nous détourner de l’histoire nationale, mais de considérer en quoi celle-ci peut informer, aujourd’hui comme demain, les histoires impériale et globale à venir.
A straightforward approach allowing three-dimensional (3D) visualization of subsurface deformation beneath nanoindents using reconstructed cross-sectional transmission electron microscopy (TEM) data is demonstrated. This approach relies on generating an array of nanoindents, extracting a thin (<200 nm) cross section using a focused ion beam (FIB) and imaging with a transmission electron microscope. By rotating the orientation of the FIB cross section with respect to the array of nanoindents at the optimal angle, it is guaranteed that a different section of each nanoindent's subsurface plastic zone is contained within the final cross section. Subsequently, TEM images corresponding to different sections are reconstructed into a 3D image of a representative nanoindentation plastic zone. This approach can be extended to any array of nominally identical features that can be patterned with regular spacing and included in a single FIB cross section. It was also found to significantly enhance the throughput of preparing routine site-specific TEM samples, even when 3D visualization is not necessary. In this article, the approach is applied to visualize the plastic zones beneath nanoindents in GaAs (001), for loads of 50–1000 µN.
Conditions in institutions for children or defectives may become peculiarly favourable to the propagation of hookworm disease. The subject of the present study is a long-standing infection with Ancylostoma duodenale in the Hospital for the Insane at Goodna, Queensland, the largest of the three hospitals for the insane maintained by the State Government. The investigation was of special interest because the institution is in a region in which the general population is free from hookworm disease, owing to low rainfall, and because the infection was with A. duodenale, while the predominating hookworm infection of Queensland is with Necator americanus.
Cet article entend montrer que la municipalité parisienne a joué un rôle central dans la négociation du rapport entre Paris et la nation française au milieu du XIXe siècle. L’instauration d’élections municipales dans la capitale sous la monarchie de Juillet a donné naissance à une culture électorale et participative locale, qui a non seulement reformulé le rapport entre les mandataires et leurs arrondissements, mais a également modifié la nature du mandat municipal grâce à l’introduction de la notion d’expertise et l’agrandissement de l’échelle d’intervention administrative locale. Cette culture participative a aussi permis l’établissement durable d’une reconnaissance mutuelle entre le pouvoir municipal de Paris et le pouvoir du gouvernement national sis dans la même ville. De cette culture électorale et participative est né un intérêt particulier parisien, rouage essentiel qui a permis à Paris de trouver sa place dans une France en voie de démocratisation.
This paper presents the development of a sensor to detect the oxidative and radiation induced degradation of polypropylene. Recently we have examined the use of crosslinked assemblies of nanoparticles as a chemiresistor-type sensor for the degradation products. We have developed a simple method that uses a siloxane matrix to fabricate a chemiresistor-type sensor that minimizes the swelling transduction mechanism while optimizing the change in dielectric response. These sensors were exposed with the use of a gas chromatography system to three previously identified polypropylene degradation products including 4-methyl-2-pentanone, acetone, and 2-pentanone. The limits of detection 210 ppb for 4-methy-2-pentanone, 575 ppb for 2-pentanone, and the LoD was unable to be determined for acetone due to incomplete separation from the carbon disulfide carrier.
SPIRE, the Spectral and Photometric Imaging Receiver, is Herschel's submillimetre camera and spectrometer. It comprises a three-band imaging photometer operating at 250, 350 and 500 μm, and an imaging Fourier Transform Spectrometer (FTS) covering 194–672 μm. The design of SPIRE is described, and the expected scientific performance is summarised, based on modelling and flight instrument test results.
The field of materials tribology has entered a phase of instrumentation and measurement that involves accessing and following the detailed chemical, structural, and physical interactions that govern friction and wear. Fundamental tribological research involves the development of new experimental methods capable of monitoring phenomena that occur within the life of a sliding contact. Measuring friction phenomena while the process is ongoing is a major improvement over earlier techniques that required the surfaces to be separated and analyzed, thereby interrupting the friction-causing event and modifying surface conditions. In the past, MRS Bulletin has highlighted how in situ approaches can greatly enhance our understanding of materials structure, processing, and performance. This issue highlights in situ approaches as applied to materials tribology, namely, the study of contacting surfaces and interfaces in relative motion.
Directly seeing into a moving contact is a powerful approach to understanding how solid lubricants develop low-friction, long-lived interfaces. In this article, we present optical microscopy and spectroscopy approaches that can be integrated with friction monitoring instrumentation to provide real-time, in situ evaluation of solid lubrication phenomena. Importantly, these tools allow direct correlation of common tribological events (such as variations in friction and wear) with the responsible sliding-induced mechanical and chemical phenomena. We demonstrate the utility of in situ approaches with applications to a variety of thin-film solid lubricants.