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The expansion of robotic surgery requires identifying factors of competent robotic bedside assisting. Surgical trainees desire more robotic console time, and we hypothesized that protocolized robotic surgery bedside training could equip Advanced Practice Providers (APPs) to meet this growing need. No standardized precedent exists for training APPs.We designed a pilot study consisting of didactic and clinical skills. APPs completed didactic tests followed by proctored clinical skills checklists intraoperatively. Operating surgeons scored trainees with 10-point Likert scale (5 not confident,5 = confident). APPs scoring5 advanced to a solo practicum. Competence was defined as: didactic test score75Of 10 APP trainees, 5 passed on initial attempt. After individualized development plans, 4 passed retesting. Differences in trainee factors were not statistically significant, but the probability of passing the practicum was50% if more than four checklists were needed.Clinical experience, not didactic knowledge, determines the probability of intraoperative competence. Increasing clinical proctoring did not result in higher probability of competence. Early identification of APPs needing individualized improvement increases the proportion of competent APPs.

We experimentally and numerically examined the localization behavior of { 10 1 ¯ 2 } extension twins in strongly and weakly textured AZ31 and ZEK100 magnesium alloys as they depart from the surface toward the center of the sheet under the mechanical action of three-point bending. Strain measurement analysis using digital image correlation revealed that twin banding occurs only in the sharply textured AZ31, but with a characteristic spacing between the bands which decreases with the twin height and applied strain. ZEK100 did not exhibit any ordered localization of bands and behaved as a “true” polycrystal. This finding is in agreement with micromechanical calculations by the present authors . We show that full-field plasticity finite element crystal plasticity model was unable to capture many important 2D features of the twin banding. This suggest that twin shear transfer, non-local effects, and the third dimension effects should be included into this model.

Alloy partitioning during heat treatment in a lightweight precipitation hardened steel was investigated using transmission electron microscopy and atom probe tomography. The mechanical properties are discussed as a function of the effect of solution treatment temperature and aging time, giving rise to variations in chemical modulation. A wrought lightweight steel alloy with a nominal composition of Fe-30Mn-9Al-1Si-1C-0.5Mo (wt. %) was solution-treated between 1173–1273 K and aged at 773 K. Lower solution treatment temperatures retained a finer grain size and accelerated age hardening response that also produced an improved work hardening behavior with a tensile strength of −1460 MPa at 0.4 true strain. Atom probe tomography indicated these conditions also had reduced modulation in the Si and Al content due to the reduced aging time preventing silicon from diffusing out of the κ-carbide into the austenite. This work provides the framework for heat-treating lightweight, age hardenable steels with high strength and improved energy absorption.

Ionic liquids have many advantages over traditional aqueous electrosynthesis for fabrication of functional nanoarchitectures, including enabling the integration of nanoparticles into traditional coatings, superhydrophobicity, nanofoams, and other hierarchical structures. Shape and size control through ionic liquid selection and processing conditions can synthesize nanoparticles and nanoarchitectures without the use of capping agents, surfactants, or templates that are often deleterious to the functionality of the resultant system. Here we give a brief overview of some recent and interesting applications of ionic liquids to the synthesis of nanoparticles and nanoarchitectures.

Background: Open ventral incisional hernia repairs with mesh reduce hernia recurrence rates to less than 10%. The Rives-Stoppa retrorectus hernia repair technique is becoming the standard of care for mesh repair of complex incisional hernias. In these hernia repairs, mesh has traditionally been fixated with transfascial sutures, but fibrin glue has been used as an alternative to reduce pain and may also reduce operative time and the risk of seroma formation. The primary objective of this study was to compare the rates of hernia recurrence and seroma formation in cancer patients who underwent Rives-Stoppa incisional hernia repair using transfascial sutures vs. fibrin glue for mesh fixation. Methods: We conducted a retrospective review of a prospectively maintained database of cancer patients at our free-standing cancer institution who underwent Rives-Stoppa ventral incisional hernia repair performed at our institution. Fisher’s exact test was used to assess differences in hernia recurrence and seroma formation rates between patients who underwent mesh fixation with transfascial sutures vs. fibrin glue. Using a neutral prior probability distribution, a Bayesian analysis was performed to evaluate the posterior probability of seroma formation requiring intervention and hernia recurrence after retrorectus repair with fibrin glue fixation. Log-rank test was used to assess the difference in overall survival between the two groups. Results: Forty-one patients (22 in the transfascial suture group and 19 in the fibrin glue group) were included in the analysis. The patient demographics were similar in both groups. There was no statistically significant difference in seroma formation requiring drainage by interventional radiology (IR) between the fibrin glue and the transfascial suture groups (5.3% vs. 9.1%; P=1.00). The odds of having a hernia recurrence was 4 times higher in the transfascial suture group than in the fibrin glue fixation group, but this was not statistically significant (18.2% vs 5.3%, p=0.35). The Bayesian analysis showed a 90% probability that the hernia recurrence rate would be higher in the transfascial suture than in the fibrin glue fixation group. Conclusion: Using fibrin glue instead of transfascial sutures may reduce hernia recurrences and seroma formation in cancer patients undergoing ventral incisional hernia repairs with retro rectus mesh. The high probability of reducing the odds of hernia recurrence with fibrin glue fixation warrants a prospective randomized, multi-institutional clinical trial.

Density functional theory was used to study the effect of rare-earth dopants on the structure, phase stability, and magnetic properties of α- and θ-Al2O3. Lanthanide series rare-earth dopants (Pr, Nd, Gd, Er, and Yb) were considered at a doping concentration of 0.83 at.%. Incorporation of rare-earth dopants was found to increase the lattice parameters and exaggerate the local structural distortion around the dopant. The extent of local lattice distortion was correlated with the dopant ionic radii. The phase stability of rare-earth-doped Al2O3 was assessed by comparing cohesive and defect formation energies for doped and undoped α- and θ-Al2O3. Rare-earth dopants increased the relative stability of the metastable θ-Al2O3, although doped α-Al2O3 remained more stable. The total magnetic moment of the doped Al2O3 was shown to correlate with the number of unpaired electrons. The magnetic moment was also found to be strongly localized on the rare-earth dopant for Er, Gd, Nd, and Pr-doped Al2O3. In contrast, the Yb dopant induced a delocalized magnetic moment on ~80% of the oxygen atoms. These results further the understanding of dopant incorporation mechanisms, as well as the doping effect on phase stability and magnetic properties that may be applied to advanced field-assisted material synthesis and processing for enhanced properties.

This study evaluates the role of thermomechanical processing and heat treatment on the microstructure and mechanical properties of a hot rolled, annealed, and aged Fe-18Mn-10Al-0.9C-5Ni (wt%) steel. The steel exhibited rapid age hardening kinetics when aged in the temperature range of 500&ndash, 600 &deg, C for up to 50 h, which has been shown in other work to be the result of B2 ordering in the ferrite and &kappa, carbide precipitation within the austenite matrix. The ultimate tensile strength increased from 1120 MPa in the annealed condition to 1230 MPa after 2 h of aging at 570 &deg, C. Charpy V-notch toughness was evaluated at &minus, 40 &deg, C in sub-sized specimens with a maximum in the annealed and quenched condition of 28.5 J in the L-T orientation.

The mechanical behavior of twinning- and transformation-induced plasticity steels, commonly referred to as TWIP and TRIP steels, are characterized by linear hardening followed by an abrupt decrease in the hardening rate. We develop an empirical model that captures salient features of the strain hardening behavior. The model emphasizes ease of implementation into computer codes and identifying parameters from macroscopic data over physically motivated parameters; however, parameters fit to the mechanical response of several alloys show a direct correlation between some parameters and stacking fault energy. Finite element simulations of TWIP and TRIP steels under uniaxial tension show the lack of post-necking elongation observed experimentally is directly related to how abruptly the hardening decreases after the linear hardening regime. A scheme is then proposed for computing some hardening parameters directly from composition so that the model is compositionally-sensitive. This method is demonstrated on medium to high Mn steels so that the mechanical behavior can be predicted using the stacking fault energy, which is computed as a function of composition.

BackgroundEarly cholecystectomy (EC) for acute cholecystitis (AC) is standard. Often patients with cancer are not EC candidates and require non-surgical treatments. We analyzed factors associated with non-surgical treatments and progression to interval cholecystectomy (IC).Materials and methodsWe performed a case–control study reviewing consults for AC from 2001 to 2017 in a tertiary cancer center. Study patients had cancer, abdominal pain, and positive imaging studies. Univariate analysis and regression modeling evaluated associations between non-surgical management, resolution of AC, and IC.Results206 patients met the criteria. 20 underwent EC, 132 took antibiotics (ABX), and were treated with 54 percutaneous cholecystostomy tubes (PCTs). AC resolution was higher with PCT versus ABX (94% vs. 80%, p=0.02). Univariate analysis revealed higher absolute neutrophil counts (ANCs) and longer length of stay in PCT, and logistic regression revealed independent associations of abdominal malignancy (OR=6.66, 95% CI 1.36 to 32.6, p=0.09), abdominal radiation (OR=0.09, 95% CI 0.02 to 0.53, pConclusionPCT has a higher success rate of resolving AC than ABX. Abdominal malignancy increases odds of resolution; abdominal radiation decreases odds. Nausea/vomiting and recent chemotherapy, coupled with rising ANC are associated with IC, but less than 50% of patients return for operation. PCT may not be a bridge to IC in our population.Level of evidence II.

The effect of 3d and 4d transition metal (TM) additions on the intrinsic stacking fault energy (SFE) in fcc Fe is studied to elucidate the role of alloying in the deformation mechanisms in austenitic steels. The results of ab initio calculations reveal that only Mn reduces the SFE, stabilizing the local hcp structure, whereas all other d-additions are expected to decrease the hcp → fcc transformation temperature and restrain the e-martensite formation. We predict a parabolic dependence of SFE on the atomic number of d-element across the series, with the largest increase in SFE obtained for the early and late elements in the d-series that follow the difference in the valence electrons between the TM and Fe atoms. To understand the SFE behavior in fcc Fe alloys, the driving forces for the fcc to hcp phase transformations of transition metal X and solid solution Fe–X were considered with an ab initio approach. It is found that the solution model explains the SFE trends for all TM additions except the late TMs with fully occupied d-shells (Cu and Ag).

We present a multi-proxy mineral record based on X-ray diffraction and diffuse reflectance spectrophotometry analysis for two cores from the western Indus Shelf in order to reconstruct changing weathering intensities, sediment transport, and provenance variations since 13 ka. Core Indus-10 is located northwest of the Indus Canyon and exhibits fluctuations in smectite/(illite + chlorite) ratios that correlate with monsoon intensity. Higher smectite/(illite + chlorite) and lower illite crystallinity, normally associated with stronger weathering, peaked during the Early–Mid Holocene, the period of maximum summer monsoon. Hematite/goethite and magnetic susceptibility do not show clear co-variation, although they both increase at Indus-10 after 10 ka, as the monsoon weakened. At Indus-23, located on a clinoform just west of the canyon, hematite/goethite increased during a period of monsoon strengthening from 10 to 8 ka, consistent with increased seasonality and/or reworking of sediment deposited prior to or during the glacial maximum. After 2 ka terrigenous sediment accumulation rates in both cores increased together with redness and hematite/goethite, which we attribute to widespread cultivation of the floodplain triggering reworking, especially after 200 years ago. Over Holocene timescales sediment composition and mineralogy in two localities on the high-energy shelf were controlled by varying degrees of reworking, as well as climatically modulated chemical weathering.

Ion implantation was used to modify the surface chemistry of magnesium in order to improve the corrosion resistance. Metalloids which have recently been shown to reduce the cathodic reaction kinetics in magnesium alloys, were implanted into high purity polycrystalline magnesium at varying doses and the composition gradient, microstructure, and electrochemical behavior were characterized. The primary chemical reactions at a magnesium alloy surface during corrosion are water reduction, wherein water is split to evolve hydrogen, and oxidation of Mg to Mg2+. Recently, germanium and arsenic have been reported to have a significant impact on the kinetics of the cathodic water reduction reaction by inhibiting the recombination of hydrogen atoms and subsequent evolution of H2 gas from the Mg surface.(1, 2) Density functional theory (DFT) has provided support for these observations indicating unfavorable enthalpy changes for adsorbed hydrogen atom diffusion toward several metals and metalloids alloyed on a magnesium surface.(3) The DFT results also showed that the reaction enthalpy of diatomic hydrogen evolution was unfavorable on a dilute Mg-metalloid surface. Ion implantation into the surface of metals has been known to improve wear and corrosion resistance, alter conductivity and optical properties, and improve thermal oxidation resistance. For example, the corrosion resistance of 1070 and 52100 steels has been improved by implanting Ta or Ti. Although lesser studied than some substrates, implantation into Mg and Mg alloys has been examined for corrosion and wear in implantable medical devices.(4-6) Implantation of Y into Mg and of Al into AZ31 is known to increase open circuit potential (OCP) and co-implantation of Cr and O is known to form a protective oxide film. This study examines the role of ion implantation in forming protective, corrosion resistant magnesium surface alloys. Germanium and arsenic ions were implanted at 1532 keV into high-purity Mg samples using a National Electrostatics 5SDH-2 positive ion accelerator at doses sufficient to achieve 1-micrometer thick doped layers with peak concentrations of 0.01-0.3 atomic percent at approximately 1.5 micrometers beneath the surface. The depth of implantation and concentration were verified using Rutherford backscattering spectrometry, and were consistent with what had been expected from the ion implantation simulation program SRIM. Energy dispersive spectroscopy, and x-ray photoelectron spectroscopy were used to characterize surface chemistry. Surface morphology was characterized using scanning electron microscopy, tunneling electron microscopy, and atomic force microscopy. Higher concentrations of Ge and As were both observed to roughen the alloy surface, generating a thick MgO surface film, whereas low doses had a minimal effect. The corrosion behavior was evaluated using potentiodynamic polarization and immersion in quiescent NaCl. In order to de-convolute the effect of surface oxide thickness from the chemical effect of the alloying addition, Mg was also implanted into the Mg substrate as a reference. 1. R. Liu, M. Hurley, A. Kvryan, G. Williams, J. Scully and N. Birbilis, Scientific Reports, 6(2016). 2. N. Birbilis, G. Williams, K. Gusieva, A. Samaniego, M. A. Gibson and H. N. McMurray, Electrochemistry Communications, 34, 295 (2013). 3. K. R. Limmer, K. S. Williams, J. P. Labukas and J. W. Andzelm, CORROSION, 73, 506 (2017). 4. C. Liu, Y. Xin, X. Tian, J. Zhao and P. K. Chu, Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 25, 334 (2007). 5. Y. Z. Wan, G. Y. Xiong, H. L. Luo, F. He, Y. Huang and Y. L. Wang, Applied Surface Science, 254, 5514 (2008). 6. R. Xu, G. Wu, X. Yang, T. Hu, Q. Lu and P. K. Chu, Materials Letters, 65, 2171 (2011).