Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher.
Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?
Some links on this page may take you to non-federal websites. Their policies may differ from this site.
-
ABSTRACT A virtual X-Ray Laboratory for Materials Science and Engineering has been developed and used as a flexible and powerful tool to help undergraduate and graduate students become familiar with the design and operation of the X-ray equipment in visual and interactive ways in order to learn fundamental principles underlying X-ray analytical methods. The virtual equipment and lab assignments have been used for: (i) authentic online experimentation, (ii) homework and control assignments with traditional and blended courses, (iii) preparing students for hands-on work in physical X-ray labs, (iv) lecture demonstrations, and (v) performance-based assessment of students’ ability to apply gained theoretical knowledge for operating actual equipment and solving practical problems. Students have also used the virtual diffractometer linked and synchronized with an actual powder diffractometer for blended experimentation. Using the associated learning and content management system (LCMS) and authoring tools, instructors kept track of students’ performance and designed new virtual experiments and more personalized learning assignments for students. The lab has also been integrated with the MITx course available on the massive open online course edX platform for Massachusetts Institute of Technology for undergraduate students.more » « less
-
more » « less
Purpose Undiagnosed dehydration compromises health outcomes across many populations. Existing dehydration diagnostics require invasive bodily fluid sampling or are easily confounded by fluid and electrolyte intake, environment, and physical activity limiting widespread adoption. We present a portable MR sensor designed to measure intramuscular fluid shifts to identify volume depletion.
Methods Fluid loss is induced via a mouse model of thermal dehydration (37°C; 15‐20% relative humidity). We demonstrate quantification of fluid loss induced by hyperosmotic dehydration with multicomponent T2 relaxometry using both a benchtop NMR system and MRI localized to skeletal muscle tissue. We then describe a miniaturized (~1000 cm3) portable (~4 kg) MR sensor (0.28 T) designed to identify dehydration‐induced fluid loss. T2 relaxometry measurements were performed using a Carr‐Purcell‐Meiboom‐Gill pulse sequence in ~4 min.
Results T2 values from the portable MR sensor exhibited strong (R2= 0.996) agreement with benchtop NMR spectrometer. Thermal dehydration induced weight loss of 4 to 11% over 5 to 10 h. Fluid loss induced by thermal dehydration was accurately identified via whole‐animal NMR and skeletal muscle. The portable MR sensor accurately identified dehydration via multicomponent T2 relaxometry.
Conclusion Performing multicomponent T2 relaxometry localized to the skeletal muscle with a miniaturized MR sensor provides a noninvasive, physiologically relevant measure of dehydration induced fluid loss in a mouse model. This approach offers sensor portability, reduced system complexity, fully automated operation, and low cost compared with MRI. This approach may serve as a versatile and portable point of care technique for dehydration monitoring.
-
more » « less
Abstract Enhanced understanding of neuropathologies has created a need for more advanced tools. Current neural implants result in extensive glial scarring and are not able to highly localize drug delivery due to their size. Smaller implants reduce surgical trauma and improve spatial resolution, but such a reduction requires improvements in device design to enable accurate and chronic implantation in subcortical structures. Flexible needle steering techniques offer improved control over implant placement, but often require complex closed‐loop control for accurate implantation. This study reports the development of steerable microinvasive neural implants (S‐MINIs) constructed from borosilicate capillaries (OD = 60 µm, ID = 20 µm) that do not require closed‐loop guidance or guide tubes. S‐MINIs reduce glial scarring 3.5‐fold compared to prior implants. Bevel steered needles are utilized for open‐loop targeting of deep‐brain structures. This study demonstrates a sinusoidal relationship between implant bevel angle and the trajectory radius of curvature both in vitro and ex vivo. This relationship allows for bevel‐tipped capillaries to be steered to a target with an average error of 0.23 mm ± 0.19 without closed‐loop control. Polished microcapillaries present a new microinvasive tool for chronic, predictable targeting of pathophysiological structures without the need for closed‐loop feedback and complex imaging.
