Enantioselective synthesis and application to the allylic imidate rearrangement of amine-coordinated palladacycle catalysts of cobalt sandwich complexes

The reaction of (η5-(N,N-dimethylaminomethyl)cyclopentadien-yl)(η4-tetraphenylcyclobutadiene)cobalt with sodium tetrachloropalladate and (R)-N-acetylphenylalanine gave planar chiral palladacycle di-μ-chloridebis[(η5-(Sp)-2-(N,N-dimethylaminomethyl)cyclopentadienyl,1-C,3′-N)(η4-tetraphenylcyclobutadiene)cobalt]dipalladium [(Sp)-Me2-CAP-Cl] in 92 % ee and 64 % yield. Enantiopurity (>98 % ee) was achieved by purification of the monomeric (R)-proline adducts and conversion back to the chloride dimer. Treatment with AgOAc gave (Sp)-Me2-CAP-OAc which was applied to asymmetric transcyclopalladation (up to 78 % ee). The (R)-N-acetylphenylalanine mediated palladation methodology was applicable also to the corresponding N,N-diethyl (82 % ee, 39 % yield) and pyrrolidinyl (>98 % ee, 43 % yield) cobalt sandwich complexes. A combination of 5 mol % of the latter [(Sp)-Pyrr-CAP-Cl] and AgNO3 (3.8 equiv) is a catalyst for the allylic imidate rearrangement of an (E)-N-aryltrifluoroacetimidate (up to 83 % ee), and this catalyst system is also applicable to the rearrangement of a range of (E)-trichloroacetimidates (up to 99 % ee). This asymmetric efficiency combined with the simplicity of catalyst synthesis provides accessible solutions to the generation of non-racemic allylic amine derivatives

Individual Nurse Productivity in Preparing Patients for Discharge Is Associated with Patient Likelihood of 30-Day Return to Hospital

Objective: Applied to value-based health care, the economic term “individual productivity” refers to the quality of an outcome attributable through a care process to an individual clinician. This study aimed to (1) estimate and describe the discharge preparation productivities of individual acute care nurses and (2) examine the association between the discharge preparation productivity of the discharging nurse and the patient’s likelihood of a 30-day return to hospital [readmission and emergency department (ED) visits]. Research Design: Secondary analysis of patient-nurse data from a cluster-randomized multisite study of patient discharge readiness and readmission. Patients reported discharge readiness scores; postdischarge outcomes and other variables were extracted from electronic health records. Using the structure-process-outcomes model, we viewed patient readiness for hospital discharge as a proximal outcome of the discharge preparation process and used it to measure nurse productivity in discharge preparation. We viewed hospital return as a distal outcome sensitive to discharge preparation care. Multilevel regression analyses used a split-sample approach and adjusted for patient characteristics. Subjects: A total 522 nurses and 29,986 adult (18+ y) patients discharged to home from 31 geographically diverse medical-surgical units between June 15, 2015 and November 30, 2016. Measures: Patient discharge readiness was measured using the 8-item short form of Readiness for Hospital Discharge Scale (RHDS). A 30-day hospital return was a categorical variable for an inpatient readmission or an ED visit, versus no hospital return. Results: Variability in individual nurse productivity explained 9.07% of variance in patient discharge readiness scores. Nurse productivity was negatively associated with the likelihood of a readmission (−0.48 absolute percentage points, P\u3c0.001) and an ED visit (−0.29 absolute percentage points, P=0.042). Conclusions: Variability in individual clinician productivity can have implications for acute care quality patient outcomes

Ice-Bed Coupling Beneath and Beyond Ice Streams: Byrd Glacier, Antarctica

Ice sheet thickness is determined mainly by the strength of ice-bed coupling that controls holistic transitions from slow sheet flow to fast streamflow to buttressing shelf flow. Byrd Glacier has the largest ice drainage system in Antarctica and is the fastest ice stream entering Ross Ice Shelf. In 2004 two large subglacial lakes at the head of Byrd Glacier suddenly drained and increased the terminal ice velocity of Byrd Glacier from 820 m yr(-1) to 900 m yr(-1). This resulted in partial ice-bed recoupling above the lakes and partial decoupling along Byrd Glacier. An attempt to quantify this behavior is made using flowband and flowline models in which the controlling variable for ice height above the bed is the floating fraction phi of ice along the flowband and flowline. Changes in phi before and after drainage are obtained from available data, but more reliable data in the map plane are required before Byrd Glacier can be modeled adequately. A holistic sliding velocity is derived that depends on phi, with contributions from ice shearing over coupled beds and ice stretching over uncoupled beds, as is done in state-of-the-art sliding theories

The formation of a nanohybrid shish-kebab (NHSK) structure in melt-processed composites of poly (ethylene terephthalate) (PET) and multi-walled carbon nanotubes (MWCNTs)

The combination of synchrotron Small- and Wide-Angle X-ray scattering (SAXS/WAXS), and thermal analysis was used to follow the evolution of crystalline morphology and crystallization kinetics in a series of melt-processed composites of poly(ethylene terephthalate) (PET) and multiwall carbon nanotubes (MWCNT). The as-extruded PET-MWCNT composites underwent both hot and cold isothermal crystallizations where a final oriented nanohybrid shish-kebab (NHSK) crystalline structure was observed. An oriented NHSK structure was seen to persist even after melting and recrystallization of the composites. From the scattering data, we propose a model whereby the oriented MWCNTs act as heterogeneous nucleation surfaces (shish) and the polymer chains wrap around them and the crystallites (kebabs) grow epitaxially outwards during crystallization. However, depending on crystallization temperature, unoriented crystallites also grow in the polymer matrix, resulting in a combination of a NHSK and lamellar morphology. In contrast, the neat PET homopolymer showed the sporadic nucleation of a classic unoriented lamellar structure under the same isothermal crystallization conditions. These results provide a valuable insight into the distinctive modification of the crystalline morphology of melt-processed polymer-MWCNT composites prior to any secondary processing, having a significant impact on the use of MWCNTs as fillers in the processing and modification of the physical and mechanical properties of engineering polymers

Evidence for a Frozen Bed, Byrd Glacier, Antarctica

Ice thickness, computed within the fjord region of Byrd Glacier on the assumptions that Byrd Glacier is in mass-balance equilibrium and that ice velocity is entirely due to basal sliding, are on average 400 m less than measured ice thicknesses along a radio-echo profile. We consider four explanations for these differences: (1) active glacier ice is separated from a zone of stagnant ice near the base of the glacier by a shear zone at depth; (2) basal melting rates are some 8 m/yr; (3) internal shear occurs with no basal sliding in much of the region above the grounding zone; or (4) internal creep and basal sliding contribute to the flow velocity in varying proportions above the grounding zone. Large gradients of surface strain rate seem to invalidate the first explanation. Computed values of basal shear stress (140 to 200 kPa) provide insufficient frictional heat to melt the ice demanded by the second explanation. Both the third and fourth explanations were examined by making simplifying assumptions that prevented a truly quantitative evaluation of their merit. Nevertheless, there is no escaping the qualitative conclusion that internal shear contributes strongly to surface velocities measured on Byrd Glacier, as is postulated in both these explanations

Effects of biceps tension and superior humeral head translation on the glenoid labrum

We sought to understand the effects of superior humeral head translation and load of the long head of biceps on the pathomechanics of the superior glenoid labrum by predicting labral strain. Using micro‐CT cadaver images, a finite element model of the glenohumeral joint was generated, consisting of humerus, glenoid bone, cartilages, labrum, and biceps tendon. A glenohumeral compression of 50 N and biceps tensions of 0, 22, 55, and 88 N were applied. The humeral head was superiorly translated from 0 to 5 mm in 1‐mm increments. The highest labral strain occurred at the interface with the glenoid cartilage and bone beneath the origin of the biceps tendon. The maximum strain was lower than the reported failure strain. The humeral head motion had relatively greater effect than biceps tension on the increasing labral strain. This supports the mechanistic hypothesis that superior labral lesions result mainly from superior migration of the humeral head, but also from biceps tension. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1424–1429, 2014.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108670/1/jor22688.pd

Effects of biceps tension on the torn superior glenoid labrum

The purpose of this study was to evaluate the role of the tension on the long head of the biceps tendon in the propagation of SLAP tears by studying the mechanical behavior of the torn superior glenoid labrum. A previously validated finite element model was extended to include a glenoid labrum with type II SLAP tears of three different sizes. The strain distribution within the torn labral tissue with loading applied to the biceps tendon was investigated and compared to the inact and unloaded conditions. The anterior and posterior edges of each SLAP tear experienced the highest strain in the labrum. Labral strain increased with increasing biceps tension. This effect was stronger in the labrum when the size of the tear exceeded the width of the biceps anchor on the superior labrum. Thus, this study indicates that biceps tension influences the propagation of a SLAP tear more than it does the initiation of a tear. Additionally, it also suggests that the tear size greater than the biceps anchor site as a criterion in determining optimal treatment of a type II SLAP tear. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1545–1551, 2015.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113101/1/jor22888.pd