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Objective The authors conducted a systematic review of the published literature to identify interventions to prevent and/or reduce burnout among medical students and residents. Methods The authors searched 10 databases (from the start of each through September 21, 2016) using keywords related to burnout, medical education, and prevention. Teams of two authors independently reviewed the search results to select peer-reviewed, English language articles describing educational interventions to prevent and/or reduce burnout among medical students and/or residents that were evaluated using validated burnout measures. They assessed study quality using the Medical Education Research Study Quality Instrument and the Cochrane Risk of Bias Tool. Results Fourteen studies met inclusion criteria and all used the Maslach Burnout Inventory as at least one measure of burnout. Four were single group pre-post studies, 6 non-randomized two-group studies, and 4 randomized controlled trials. None of the studies were designed specifically to target burnout prevention. In 12 studies, residents were the targeted learners. Six of the 14 studies reported statistically significant changes in burnout scores: 5 reported improvement and 1 reported worsening of burnout. Of the 5 studies that reported statistically significant benefit, 1 studied a complementary and alternative medicine elective, 1 studied the Respiratory One Meditation method, and 3 studied duty hour changes. Conclusions This review highlights the need for rigorously designed studies in burnout prevention and reduction among residents and especially medical students.

The effect of surface chemistry on the tribological performance and reliability of a MEMS lateral output motor is reported. Relative humidity (RH) and octadecyltrichlorosilane (OTS) self-assembled monolayer (SAM) coatings were used to change surface chemistry. Electrical and tribological performance of uncoated and OTS-coated motors were found to be dependent on RH. For uncoated motors, excessive wear of sliding contacts and welding (permanent adhesion) of static contacts were observed at 0.1% RH. Degradation of electrostatic force and high static friction (stiction) forces limited dynamic performance and reliability and caused device sticking at and above 70% RH. Around 50% RH, uncoated motors exhibited negligible wear, low adhesion, and a wear life at least three orders of magnitude longer than in the dry environment (experiments were stopped without failure after about one billion cycles). Water vapor behaved as a gas phase replenishable lubricant by providing a protective adsorbed film. The OTS coating broadened the operating envelope to 30–50% RH and reduced stiction, which allowed better dynamic performance at high RH. The OTS coating improved durability at 0.1% RH, but it was still poor. At high RH, stiction problems reoccurred when the OTS coating was worn away. By controlling and balancing surface chemistry (adsorbed water and OTS), excellent performance, low friction and wear, and excellent durability were attained with the lateral output motor.

A lubrication scheme for MEMS electrostatic lateral output motors based on a mixture of bound and mobile lubricant was studied. Lubrication by bound monolayer alone provided some increase in operational life, but after a short time, the film wore away and the device failed in the unlubricated mode. A mobile phase was used to provide lubricant replenishment. Tribological studies were conducted on Si(100) wafers, as well as on MEMS electrostatic lateral output motors, dip-coated with a mixture of bound and mobile phases of Fomblin Zdol. Accelerated screening tests on Si(100) wafers were undertaken using a pin on disk tribometer. However, the optimum balance of bound and mobile phases was determined by studies on the device itself. The fractional surface coverage of lubricant and the ratio of bound to mobile phase was varied through selection of reaction temperature and rinse chemistry. The mobile phase on model surfaces and devices acted as a source of lubricant replenishment, and together with the bound phase provided dramatic improvement in performance. The wide variation seen in the performance of individual devices suggests that dip coating does not provide a uniform coating on the contacting surfaces of these devices.

Ionic liquids were studied to determine their effectiveness as boundary lubricant additives for water. The chemical and tribochemical reactions that govern their behavior were probed to understand lubrication mechanisms. Under water lubricated conditions, silicon nitride ceramics are characterized by a running-in period of high friction, during which time the surface is modified causing a dramatic decrease in friction and wear. Two mechanisms have been proposed to explain the friction and wear behavior. Si3N4 sliding against itself may result in tribochemical reactions that form a hydrated silicon oxide layer on the surface of the sliding contact. This film has been suggested to mediate friction and wear. Others have suggested that tribo-dissolution of SiO2 results in an ultra smooth surface and after a running-in period of high wear, the lubrication mode becomes hydrodynamic. The goal of this study was to examine the effects that ionic liquids have on the friction and wear properties of Si3N4, in particular their effects on the running-in period. Tribological properties were evaluated using pin-on-disk and reciprocating tribometers. The tribological conditions of the tests were selected to produce mixed/hydrodynamic lubrication. The relative lubrication mode between mixed and hydrodynamic was controlled by the initial surface roughness. Solutions containing 2 wt% ionic liquids were produced for testing purposes. Chemical analysis of the sliding surfaces was accomplished with X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The test specimens were 1 in diameter Si3N4 disks sliding against 1/4 in Si3N4 balls. The addition of ionic liquids to water resulted in dramatically reduced running-in periods for silicon nitride from thousands to the hundreds of cycles. Proposed mechanisms include the formation of BFx and PFx films on the surface and creation of an electric double layer of ionic liquid.

An advanced ball-on-disk tribometer was developed for in situ studies of friction, wear, and contact condition during sliding. Kinetic friction force, contact resistance (Rc), acoustic emission (AE), ball position perpendicular (⊥) to the plane of the disk (ball and disk wear), and disk surface reflectance (disk wear) were all measured simultaneously during sliding experiments. Metal (440C steel) balls were slid against ceramic (n-doped polysilicon) wafers at light load (10g) and short test duration (2.5min). Significant changes in measured parameters were observed as sliding progressed. These changes are discussed, and when considered together provide new insights into friction and wear mechanisms not readily obtainable from more standard tribometers. The effects of disk run-out (effective surface waviness) on μ and Rc were also investigated. Friction and Rc were periodic with a period equal to the period of disk rotation. The behavior was complex, but generally going up a hill increased μ and decreased Rc, with the opposite behavior going down a hill. We established a critical link between low-frequency friction oscillations (LFFO) and the nature of the contact between sliding surfaces (Rc measurement). The geometric ratchet mechanism was ruled out as a cause of LFFO, as the surface slope was too small to explain the large friction oscillations. Coating the balls and wafers with lower friction materials resulted in negligible LFFO, which makes it unlikely that LFFO were simply a result of an oscillating normal force created by dynamic effects. LFFO likely have their origins in the complex nature of the contact between rubbing surfaces.

The synthesis of hollow nanoparticles of tungsten disulphide, which offers some exciting possibilities for a new generation of solid lubricants, is reported. The possible applications for the nanoparticles and their atomic structures are presented.

The present work reports on the comparison of tribological properties between quasicrystalline and approximant films under steam and water lubrication. These films have nearly the same stoichiometry, which allows evaluation of the quasicrystalline structure as compared with the crystalline structure of the approximant. The goal of this study is to determine the effects crystal structure has on tribological properties and to study the general tribological behavior of quasicrystals in a steam and water environment. AlCuFe quasicrystals coatings were deposited by unbalanced magnetron sputtering. The test films were 10 μm thick deposited on a 1inch diameter Al2O3 disk and a 1/4inch diameter Al2O3 ball. Data were collected under water and steam lubricated conditions. Friction coefficients and wear rates of quasicrystals and approximants were nearly indistinguishable. During water lubrication, quasicrystals act similar to ceramics where surface smoothing and hydrodynamic lift control the friction and wear properties. With steam-lubricated conditions, the friction and wear process is controlled by brittle fracture and third body abrasion. Generally, less than 5% difference in the friction and wear properties were observed between the icosahedral quasicrystal phase and the approximant phase.

Cover crops during summer fallow have been rarely researched in the semiarid northern Great Plains. This study was conducted during 2012–2019 at four Montana locations and included four functional groups (Brassica family, fibrous‐rooted crops, legumes, and tap‐rooted crops). Eleven treatments included sole functional groups, a Full Mix, the Full Mix minus each functional group, pea, and chemical fallow. Wheat (Triticum aestivum L.) was grown after each cover crop year with three nitrogen (N) fertilizer rates. Cover crops were terminated with herbicide at first flower stage of pea (Pisum sativum L.) 57 to 66 days after planting. Shoot biomass averaged 2.0 Mg ha−1 over eight site‐years representative of dryland farming in Montana. Using equal overall plant densities, treatments with six species averaged 13% greater biomass than two species. Measured at termination to a 0.9‐m depth, Fallow held greater soil water than cover crop treatments, with Fallow averaging 57 mm greater than the Full Mix. Soil nitrate averaged 49 kg N ha−1 greater after Fallow than the Full Mix; the Legume treatment averaged 26 kg N ha−1 greater than the Minus Legume treatment. Wheat yield on Fallow averaged 0.85 Mg ha−1 greater than the Full Mix in 5 of 10 site‐years, mainly at the driest site‐years. The Legume treatment elevated wheat protein over the Minus Legume treatment by an average of 15 g kg−1. Cover crops grown during summer fallow reduced soil nitrate‐N, soil water, and wheat yields compared with chemical fallow, especially in the major wheat growing region of north central Montana. Core Ideas Soil improvement via cover crop growth is an uncertain trade‐off with soil water and nitrogen use. May–June rainfall best predicted cover crop biomass (Y = 757 + 12.4X; Adj. R2 = 0.72; p < 0.01). Cover crop treatments that included six crop species averaged 13% greater biomass than those with only two species. An eight‐species cover crop mix averaged 57 mm less soil water and 49 kg ha−1 less soil N compared with fallow. Wheat yield on fallow averaged 0.85 Mg ha−1 (22%) greater than cover crops for 5 of 10 site‐years.