Selective dehydrogenation of ammonia borane to polycondensated BN rings catalysed by ruthenium olefin complexes.

Dehydrogenation of ammonia borane to well-defined products is an important but challenging reaction. A dinuclear ruthenium complex with a Ru-Ru bond bearing a diazadiene (dad) unit and olefins as non-innocent ligands catalyzes the highly selective formation of conjugated polycondensed borazine oligomers (BNH), predominantly BNH, the BN analogue of superbenzene.

The Learning Curve for Peroral Endoscopic Myotomy in Latin America: A Slide to the Right?

Background/aims: Peroral endoscopic myotomy (POEM) has been increasingly used for achalasia in Latin America, where Chagas disease is prevalent, and this makes POEM more challenging. The aim of this study was to determine the learning curve for POEM in Latin America.

Methods: Patients undergoing POEM in Latin America with a single operator were included from a prospective registry over 4 years.

Highly Efficient Base-Free Dehydrogenation of Formic Acid at Low Temperature.

The ruthenium complex [RuH (PPh ) ] is a competent catalyst for the selective dehydrogenation of formic acid (FA) at low temperature. It tolerates water and shows excellent performance (TOF up to 36 000 h at 60 °C). Remarkably, no basic additives are necessary to obtain such high activity and the defined complex is stable for up to 120 days, making this system one of the most effective formic acid dehydrogenation catalysts known to date.

Peroral endoscopic myotomy as salvation technique post-Heller: International experience.

Background: Treatment for achalasia has traditionally been Heller myotomy (HM). Despite its excellent efficacy rate, a number of patients remain symptomatic post-procedure. Limited data exist as to the best management for recurrence of symptoms post-HM.

Symplectic time-average propagators for the Schrödinger equation with a time-dependent Hamiltonian.

Several symplectic splitting methods of orders four and six are presented for the step-by-step time numerical integration of the Schrödinger equation when the Hamiltonian is a general explicitly time-dependent real operator. They involve linear combinations of the Hamiltonian evaluated at some intermediate points. We provide the algorithm and the coefficients of the methods, as well as some numerical examples showing their superior performance with respect to other available schemes.

Optical coherence tomography (OCT) prior to peroral endoscopic myotomy (POEM) reduces procedural time and bleeding: a multicenter international collaborative study.

Background: Per-oral endoscopic myotomy (POEM) has emerged as an endoscopic treatment of achalasia. There are no pre-procedural imaging modalities to predict the safest and the most efficacious approach.

Aim: To evaluate the use of optimal coherence tomography (OCT) in providing a pre-procedural esophageal assessment.

The MVAD pump: motor stator core loss characterization.

Unlabelled: Investigation of the miniature ventricular assist device (MVAD) pump motor stator core loss behavior was conducted. During operation, the ferromagnetic core in the pump's motor is magnetized by alternating magnetic fields, which, in turn, create intrinsic energy losses in the core material; these losses are known as core losses. A core loss fixture and a method to characterize the magnetic behavior of the MVAD pump stator over a range of frequencies were developed.

Peroral endoscopic myotomy: establishing a new program.

Achalasia is an esophageal motility disorder characterized by incomplete relaxation of the lower esophageal sphincter (LES) and aperistalsis of the esophageal body. Treatment of achalasia is aimed at decreasing the resting pressure in the LES. Peroral endoscopic myotomy (POEM), derived from natural orifice transluminal endoscopic surgery (NOTES) and advances in endoscopic submucosal dissection (ESD), presents a novel, minimally invasive, and curative endoscopic treatment for achalasia.

Short-term in vivo performance of the Cleveland clinic PediPump left ventricular assist device.

The PediPump was implanted in six healthy lambs (mean 25.6 ± 1.4 kg) between the left ventricular apex and the descending aorta to evaluate in vivo performance for up to 30 days.

Solving the Schrödinger eigenvalue problem by the imaginary time propagation technique using splitting methods with complex coefficients.

The Schrödinger eigenvalue problem is solved with the imaginary time propagation technique. The separability of the Hamiltonian makes the problem suitable for the application of splitting methods. High order fractional time steps of order greater than two necessarily have negative steps and cannot be used for this class of diffusive problems.

Development of a pump flow estimator for rotary blood pumps to enhance monitoring of ventricular function.

Estimation of instantaneous flow in rotary blood pumps (RBPs) is important for monitoring the interaction between heart and pump and eventually the ventricular function. Our group has reported an algorithm to derive ventricular contractility based on the maximum time derivative (dQ/dt(max) as a substitute for ventricular dP/dt(max) ) and pulsatility of measured flow signals. However, in RBPs used clinically, flow is estimated with a bandwidth too low to determine dQ/dt(max) in the case of improving heart function.

Cycle testing of the MagScrew total artificial heart external battery pack: update I.

MagScrew total artificial heart (TAH) external battery pack (EBP) cycle bench testing continued over a period of 18 months using two fresh Wilson Greatbatch lithium ion EBPs during continuous charge and discharge cycles under a simulated TAH system current requirement. The same electronic load developed for our initial testing was used to simulate the MagScrew current waveforms typically observed during nominal operation. The current load profiles for this test were modified from the ones previously described and applied to the EBP under test during a voltage-defined discharge cycle.

On processed splitting methods and high-order actions in path-integral Monte Carlo simulations.

Processed splitting methods are particularly well adapted to carry out path-integral Monte Carlo (PIMC) simulations: since one is mainly interested in estimating traces of operators, only the kernel of the method is necessary to approximate the thermal density matrix. Unfortunately, they suffer the same drawback as standard, nonprocessed integrators: kernels of effective order greater than two necessarily involve some negative coefficients. This problem can be circumvented, however, by incorporating modified potentials into the composition, thus rendering schemes of higher effective order.

The PediPump: a versatile, implantable pediatric ventricular assist device--update IV.

Cleveland Clinic's PediPump (Cleveland, OH, USA) is a ventricular assist device designed for the support of pediatric patients. The PediPump is a mixed-flow ventricular assist device with a magnetically suspended impeller measuring 10.5 mm in diameter by 64.

Initial acute in vivo performance of the Cleveland Clinic PediPump left ventricular assist device.

The PediPump is a small ventricular assist device (VAD) with a hydraulic output range designed to support children from newborns to adolescents. The present report describes our initial evaluation of the PediPump as a left VAD in an acute sheep model. The PediPump was implanted in two sheep (50.

The PediPump: a versatile, implantable pediatric ventricular assist device-update III.

The PediPump is a passive magnetic bearing, mixed flow, rotary ventricular assist device designed to provide support for the entire range of patient sizes encountered in pediatrics. Blood enters axially at the inlet and is accelerated and turned in the impeller to exit the pump at an intermediate angle. The size of the PediPump facilitates standard cannulation strategies with substantially downsized components.

Cycle testing of the MagScrew total artificial heart external battery pack.

MagScrew total artificial heart (TAH) external battery pack (EBP) cycle bench testing was conducted on two Wilson Greatbatch (Clarence, NY, USA) lithium ion EBPs over a period of 22 months during continuous charge and discharge cycles under a simulated TAH system current requirement. A custom electronic load was developed to simulate the MagScrew current waveforms typically observed during nominal operation. These current load profiles were applied to the EBP under test during a voltage-defined discharge cycle.

Early stages of development of the Taenia solium metacestode in pigs.

In order to identify the early stages of Taenia solium metacestodes, 12 pigs were each fed 100,000 viable eggs and later killed and necropsied at different times after infection. Hematoxylin-eosin (HE) and immunohistochemical techniques (IHCs) were used to identify onchospheres and cysticerci in different tissues. At 2 days postinfection (dpi) structures compatible with onchospheres were found in the lumen of the small intestine, and in the mesenteric blood vessels and lymph nodes.

Minimal sensor count approach to fuzzy logic rotary blood pump flow control.

A rotary blood pump fuzzy logic flow controller without flow sensors was developed and tested in vitro. The controller, implemented in LabView, was set to maintain a flow set point in the presence of external pressure disturbances. Flow was estimated as a function of measured pump's delta P and speed, using a steady-state, nonlinear approximation.

Development and testing of portable pump for the induction of profound hypothermia in a Swine model of lethal vascular injuries.

Unlabelled: Rapid induction of a profound hypothermic state (suspended animation) can maintain viability of key organs during repair of lethal injuries. Conventional cardiopulmonary bypass equipment (roller pump) used to induce and reverse hypothermia is expensive, bulky, requires standard electricity, and is not transportable. Development of a small, portable, battery operated, disposable, pump can logistically facilitate induction and maintenance of hypothermia.

Symplectic splitting operator methods for the time-dependent Schrodinger equation.

We present a family of symplectic splitting methods especially tailored to solve numerically the time-dependent Schrodinger equation. When discretized in time, this equation can be recast in the form of a classical Hamiltonian system with a Hamiltonian function corresponding to a generalized high-dimensional separable harmonic oscillator. The structure of the system allows us to build highly efficient symplectic integrators at any order.

Comment on "Structure of positive decompositions of exponential operators".

An elementary proof is shown on the necessary existence of negative coefficients in splitting methods of order p > or = 3.

Performance and reliability of the CPB/ECMO Initiative Forward Lines Casualty Management System.

The Cleveland Clinic Foundation CPB/ECMO Initiative Forward Casualty Management System is an economical, compact, transportable, disposable system designed to permit a rapid expansion of trauma management services requiring cardiopulmonary bypass (CPB) or extracorporeal membrane oxygenation (ECMO) pulmonary support. The system, composed of a rotary blood pump, a pump motor driver, and an electronic control console as the blood pumping subsystem, also includes commonly used compatible commercial oxygenators, venous reservoirs, and cannulae. In vitro durability testing accumulated over 100 hours without failure.

MagScrew TAH: an update.

The MagScrew Total Artificial Heart (TAH) system is the result of a close collaboration among the Cleveland Clinic Foundation, Foster Miller Technologies, Wilson Greatbatch Ltd, and Whalen Biomedical Inc. The system components are the thoracic blood pumping unit with attached compliance chamber and refill port, implantable electronic control unit, implantable battery pack, transcutaneous energy transmission system, external battery pack, and a telemetry system for communication with the electronic control unit. System in vitro tests are underway for system characterization and durability demonstration, whereas in vivo tests were conducted to evaluate system performance and biocompatibility under physiologic conditions.

A portable cardiopulmonary bypass/extracorporeal membrane oxygenation system for the induction and reversal of profound hypothermia: feasibility study in a Swine model of lethal injuries.

The Cleveland Clinic Foundation's (CCF) cardiopulmonary bypass/extracorporeal membrane oxygenation (CPB/ECMO) system capabilities were tested in a hypothermia trauma management feasibility study in a porcine animal model at the Uniformed Services University of the Health Sciences (USUHS, Bethesda, MD, U.S.A.