Magnesium production by molten salt electrolysis with liquid tin cathode and multiple effect distillation.

Low-cost clean primary production of magnesium metal is important for its use in many applications, from light-weight structural components to energy technologies. This work describes new experiments and cost and emissions analysis for a magnesium metal production process. The process combines molten salt electrolysis of MgO using MgF2-CaF2 electrolyte and a reactive liquid tin cathode, with gravity-driven multiple effect thermal system (G-METS) distillation to separate out the magnesium product, and re-use of the tin. Electrolysis experiments with carbon anodes showed current yield above 90%, while a yttria-stabilized zirconia solid oxide membrane (SOM) anode experiment showed 84% current yield. G-METS distillation is an important component of the envisioned process. It can potentially lower costs and energy use considerably compared with conventional magnesium distillation. Techno-economic analysis including detailed mass and energy balances shows that this electrolyte composition could lower costs by utilizing CaO, which is the primary impurity in MgO, as the Hall-Héroult process uses the sodium impurity in alumina. Analysis options include: raw material types (magnesite rock vs. brine or seawater), drying and calcining using electricity vs. natural gas, and carbon vs. SOM anode type. Using SOM inert anodes results in a cost premium around 10%-15%, mostly due to higher electrical energy usage resulting from membrane resistance, and reduces GHG emissions by approximately 1 kg CO2/kg Mg product. Capital and operating cost estimates, and cradle to gate greenhouse gas (GHG) emissions analysis under several raw material and process technology scenarios, show comparable costs and emissions to those of aluminum production.

Teaching Medical Students Optimal Consulting Skills: The Challenge of Generating Better Referring Physicians.

Rationale and objectives We sought to incorporate a new teaching module into the traditional medical student radiology clerkship, to improve the necessary skills for future referring physicians. Materials and methods A new required and graded module was introduced in 2014 into the radiology clerkship in year three of medical school: the Mystery Case. Each student was provided a unique and undifferentiated case from a dedicated teaching file containing de-identified images and requisition data. Students were expected to complete three serial tasks over one week: 1) prepare a voice recognition-derived, structured radiological report utilizing appropriate and relevant vocabulary; 2) discuss pertinent additional clinical information; and 3) discuss appropriate follow-up imaging, in addition to information on how to best prepare patients for these potential patient exams (e.g., with or without contrast, bowel preparation, and length of study). Students were provided written examples and dedicated class instruction with interactive discussions covering specific cases and associated related cases through random pairing with radiology resident and attending mentors. At the close of the week, students gave brief oral presentations of their cases and submitted the tasks for a written evaluation. Upon completion of the clerkship, the students completed a Likert-type six-item survey to evaluate the perceived improvement in select skills. Results The survey was completed by 82% (54/66) of the enrolled students, with 85% finding the Mystery Case an effective use of time. Medical students perceived an improved awareness of the patient care process (77%), awareness of the medical imaging resources available (89%), ability to understand a radiology report (74%), and ability to advise patients (69%). Conclusion Introduction of the Mystery Case as a graded exercise in the medical school radiology clerkship was perceived by students as effective use of time, with an improvement in the skills essential for future referring physicians.

Sex differences in forebrain and cardiovagal responses at the onset of isometric handgrip exercise: a retrospective fMRI study.

In general, cardiac regulation is dominated by the sympathetic and parasympathetic nervous systems in men and women, respectively. Our recent study had revealed sex differences in the forebrain network associated with sympathoexcitatory response to baroreceptor unloading. The present study further examined the sex differences in forebrain modulation of cardiovagal response at the onset of isometric exercise. Forebrain activity in healthy men (n = 8) and women (n = 9) was measured using functional magnetic resonance imaging during 5 and 35% maximal voluntary contraction handgrip exercise. Heart rate (HR), mean arterial pressure (MAP), and muscle sympathetic nerve activity (MSNA) were collected in a separate recording session. During the exercise, HR and MAP increased progressively, while MSNA was suppressed (P < 0.05). Relative to men, women demonstrated smaller HR (8 +/- 2 vs. 18 +/- 3 beats/min) and MAP (3 +/- 2 vs. 11 +/- 2 mmHg) responses to the 35% maximal voluntary contraction trials (P < 0.05). Although a similar forebrain network was activated in both groups, the smaller cardiovascular response in women was reflected in a weaker insular cortex activation. Nevertheless, men did not show a stronger deactivation at the ventral medial prefrontal cortex, which has been associated with modulating cardiovagal activity. In contrast, the smaller cardiovascular response in women related to their stronger suppression of the dorsal anterior cingulate cortex activity, which has been associated with sympathetic control of the heart. Our findings revealed sex differences in both the physiological and forebrain responses to isometric exercise.

Ventral medial prefrontal cortex and cardiovagal control in conscious humans.

The autonomic nervous system plays a critical role in regulating the cardiovascular responses to mental and physical stress. Recent neuroimaging studies have demonstrated that sympathetic outflow to the heart is modulated by the activity of the anterior cingulate cortex (ACC). However, the cortical modulation of cardiovagal activity is still unclear in humans. The present study used functional MRI to investigate the cortical network involved in cardiovagal control. Seventeen healthy individuals performed graded handgrip exercise while heart rate (HR) and cortical activity were recorded. Muscle sympathetic nerve activity (MSNA), mean arterial pressure (MAP) and HR were measured while participants repeated the same protocol in a parallel experiment session. The handgrip exercise elevated HR and MAP without concurrent elevations in MSNA supporting earlier conclusions that the cardiovascular responses are mainly modulated by vagal withdrawal. The imaging data showed activation in the insular cortex, thalamus, parietal cortices and cerebellum during the exercise period. Consistently across all the participants, the HR response correlated with the deactivation in the ventral medial prefrontal cortex (vMPFC), which has substantial anatomical connection with the subcortical autonomic structures. The deactivation of the vMPFC was independent of the motor control and was observed commonly in both left and right hand exercise. Stronger vMPFC deactivation was observed when participants completed a higher intensity exercise that elicited a larger HR response. Our findings support the hypothesis that the vMPFC is involved in modulating the vagal efferent outflow to the heart and the suppression of its activity elevates cardiovascular arousal in conscious humans.