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Background Isolated mammalian hearts have been used in numerous studies that have led to many important discoveries in cardiac physiology, pharmacology, and surgery. Multiple methods of perfusion have been described including retrograde and/or antegrade flows and crystalloid or blood perfusates. Furthermore, multiple species have been utilized for such studies including the following: rat, rabbit, guinea pig, canine, and swine. The objective of this study was to describe a unique isolated heart preparation, utilizing human hearts not viable for transplant, which allows for physiologic perfusion and endocardial imaging. Methods Utilizing standard cardiac transplantation procedures, 12 human hearts deemed not viable for transplant were explanted to an isolated heart apparatus. A clear, modified Krebs-Henseleit buffer was used as a blood substitute, which allowed for endocardial imaging utilizing 6.0 mm endoscopic video cameras inserted into the cardiac chambers. The hearts were perfused in Langendorff (retrograde) and/or working (physiologic) mode. Results Eleven of 12 hearts achieved the following performance in working mode: peak left ventricular pressure of 21.5 to 75.8 mm Hg, with an average of 42.7 ± 19.9 mm Hg. Intracardiac anatomical imaging was possible in all hearts, providing unique views of normal and pathological endocardial anatomy as well as biomedical device-heart interactions. Conclusions We have described a unique isolated heart preparation with which we have successfully reanimated 11 human hearts deemed not viable for transplant, perfused them by working mode, and performed intracardiac anatomical imaging. This approach provides a novel means for obtaining images of functional human cardiac anatomy and various types of unique biomedical assessments.

We present results of magnetization and magnetic anisotropy measurements in thin magnetic films of the alloys Ni81Fe19; Co90Fe10 and Ni65Fe15Co20 that are commonly used in magnetoelectronic devices. The films were sandwiched between layers of Ta. At room temperature the critical thickness for all the films to become ferromagnetic is in the range 11–13 ( A. In Co90Fe10 the coercivity and the anisotropy field both depend strongly on layer thickness.

Background . Opioid receptor agonists are involved in ischemic preconditioning and natural hibernation. The aim of this study was to determine whether pretreatment with d-Ala2-Leu5-enkephalin or morphine confers cardioprotection in large mammalian hearts. We assessed myocardial functional recovery and global energy metabolism after ischemic cold storage. Methods . After pretreatment with d-Ala2-Leu5-enkephalin, morphine sulfate, or saline (n = 6 each), swine hearts were excised and stored for 75 minutes at 4°C, then reperfused in a four-chamber isolated working heart apparatus. Serial myocardial biopsies were performed to assess cellular energy metabolism. Results . Improved systolic (cardiac output, contractility) and diastolic (tau) left ventricular functions were observed in hearts pretreated with d-Ala2-Leu5-enkephalin or morphine. These benefits were not correlated with changes in high-energy phosphate levels. Cardiac enzyme leakage (creatine kinase, troponin-I) was similar among treated and control groups. Lactate efflux increased significantly in controls, but not in opioid-pretreated hearts ( p Conclusions . d-Ala2-Leu5-enkephalin and morphine pretreatments improve postischemic function after cold storage of swine hearts. Postischemic lactate reduction, but not high-energy phosphate levels, may account for the observed cardioprotective effects.

Magnetic tunnel junctions consisting of permalloy and cobalt thin film electrodes, separated by a thin aluminum oxide tunnel barrier, have been fabricated by e-beam lithography at dimensions down to 120 nanometers. The devices are fabricated by sputter deposition and ion milling. They exhibit magnetoresistances of up to 22% at room temperature. Evidence of individual domain switching is observed. The smaller junctions have resistances in the kilohm range, which are easily measured, leading to the possibility of sensing and microelectronic applications.

We report on the deposition and characterization of SrTiO 3 / YBa 2 Cu 3 O 7− δ bilayers with SrTiO 3 thickness up to 0.7 μm. The films were grown by laser ablation onto NdGaO 3 and also onto Nb-doped SrTiO 3 substrates. Investigations by X-ray diffraction revealed very good crystallinity and (100) orientation of the SrTiO 3 films. The relative permittivity was found to increase from 320 at room temperature to 780 at 65 K. The dielectric breakdown of a 4500 A thick SrTiO 3 film at 4.2 K occurred asymmetrically at 6.2×10 4 V/cm and 2.2×10 5 V/cm. The highly oriented YBa 2 Cu 3 O 7− δ films deposited on top of these insulating layers had T c ( R =0) > 90 K and J c (77 K )≳2.7×10 6 A / cm 2 .

Multilayer edge junction SQUIDs have been fabricated using epitaxial, laserablated films of YBaCuO for both elctrodes. The barrier region is defined by a low voltage plasma oxy-flouridation step. The SQUIDs are patterned using photolithography and ion milling and devices have been made with linewidths as small as 2μm. The edge junction SQUIDs have exhibited very low magnetic hysteresis values of ≤ 50 ppm.

Superconducting Quantum Interference Devices (SQUIDs) that operate at 77 K have now been fabricated by many groups from high temperature superconductors. We will examine the performance of high-Tc SQUIDs, including the issues of the periodicity and hysteresis of the response, the magnitude of the noise in the SQUIDs, and the manufacturability of the devices. The nature of the junctions forming the SQUIDs, which have been naturally occurring grain boundaries in all but a few of the reported devices, and the physical mechanisms responsible for the noise sources will also be reviewed. The possible applications of these and future high-Tc SQUIDs will be examined.

A single-column technique is described for separating the naturally occurring nicotinic acid- and nicotinamide-containing nucleosides and nucleotides. A unique feature of the system is the use of conductivity measurements as a reproducible means of peak identification. The chromatographic system has been used to isolate a number of NADP + analogs and to characterize their enzymatic hydrolysis products. These analogs include the α-anomer of NADP + , the nicotinic acid analog of NADP + , and a series of NADP + derivatives that contain phosphate in the 3′-position.

We have investigated various compositions of Ba-Y-Cu-O, resulting in the preparation of single phase 90 K superconducting material of composition (Ba 0.67 Y 0.33 )CuO 3− δ and the identification of the structure of this superconducting phase by lattice imaging as a layered perovskite. The single phase material had a resistive transition with a midpoint at 92 K and a 1.3 K width (10%–90%) as well as a sharp low-field (H = 0.01 Oe) susceptibility transition.

This paper reports on progress made at IBM in the fabrication of HiTc dc SQUIDs (Superconducting QUantum Interference Devices) 1,2 . We have fabricated SQUIDs from polycrystalline YBa 2 Cu 3 O y samples on MgO substrates 3 and from epitaxial films on SrTiO 3 (100) substrates 4 . The films were patterned using either ion-implanting to selectively convert the superconductor into an insulator without actually removing any material 1,5 , laser ablation to pattern a loop into the film by removing material 6 , or a conventional ion milling process to selectively remove material using a photoresist mask. In the case of the polycrystalline films, the naturally occurring grain boundaries provide the weak link or Josephson junction behavior in a stripe that is much larger in size than the superconducting coherence length. We have measured the noise amplitude of one such SQUID made on MgO to be about1 × 10 -5 Φ O /Hz 1/2 at 1000 Hz and 40 K. Loops formed from true epitaxial films containing many twin boudaries will not operate as dc SQUIDs unless the films are damaged across each link. A SQUID formed in this way operated in liquid nitrogen and had an estimated white noise performance of1 × 10 -3 Φ 0 /Hz 1/2 at 74 K.

Mixtures of NADH and NADP+ or NADPH and NAD+ were incubated and periodically assayed for hydrogen transfer by measuring the formation of NADPH and NADH with glutathione reductase (NAD(P)H: oxidized-glutathione oxidoreductase, EC 1.6.4.2) and lactate dehydrogenase (L-lactate: NAD+ oxidoreductase, EC 1.1.1.27), respectively. Each mixture showed a steady nonenzymic transfer of hydrogen from the reduced to the oxidized pyridine nucleotide to yield a product that was completely enzymically active. The results demonstrate the specific nonenzymic transfer of hydrogen from NADH and NADPH to the pyridine C-4 position of NADP+ and NAD+, respectively.

A series of noncontact magnetic measurements on high-quality single crystals of Y1Ba2Cu3O7 − x have enabled us to demonstrate that the superconducting-state properties of Y1Ba2Cu3O7 − x are those of a conventional, anisotropic superconductor with the anisotropy being associated with the highly conducting Cu O sheets in the Y1Ba2Cu3O7 − x crystal structure. The anisotropy in the superconducting state is reflected most strongly in the critical current anisotropy, which is as large as 20 to 1 at low temperatures and low fields and gets arbitrarily large at higher temperatures and higher fields. The upper critical field HC2 shows an anisotropy that varies from 6:1 to 10:1 in different crystals of high quality. Along the copper-oxygen sheets the upper critical field is enormous, extrapolating to ∼60 Tesla by 77 K and implying a low-temperature Ginzburg-Landau coherence length normal to the layers of 2A− 4A. Strong upward curvature is evident in the HC2 data in both orientations of applied field. This curvature can be interpreted in terms of thermodynamic fluctuations, and, if this explanation is correct, the critical region is enormous, extending more than 25 K below TC.

The full-energy peak efficiency in a particular geometry of a collimated 3 mm × mm2 Si(Li) detector with 0.5 mil thick beryllium and Mylar windows was determined over the energy range 3.3–136 keV by measuring the absolute intensities of X- and low-energy γ-rays from the decays of intensity-calibrated sources of 241Am, 57Co, 137Cs and 65Zn. The measured efficiencies were fitted to a simple analytic function of photon energy, with the fit showing good agreement with the data over the entire range of energies. The physical basis of the model as well as the meaningfulness of its parameters is discussed. A discrepancy between the fit and the measured efficiency of the 17.75 keV Lβ + Lη X-rays from 241Am decay required a re-evaluation of the intensity per decay for these transitions. Some peculiarities of the low-energy efficiency response are discussed and are attributed to source self-absorption effects. The extension of the calibration to lower energies would be possible if more low-energy photon sources with known X-ray intensities were available. The use of L X-rays and L/K intensity ratios calculated from published data for medium-Z elements is discussed and is considered to be feasible for this extension purpose. Some radio-nuclides that are likely to be useful in the low-energy region are suggested.

Critical field and critical current density measurements performed on single crystals of Y 1 Ba 2 Cu 3 O 7- x demonstrate that its superconducting properties are those of a conventional superconductor with uniaxial ansiotropy. The high temperature upper critical field anisotropy is temperature independent except very near T c , and in the best crystal had a value of 7:1. The anisotropy in the critical current density is larger than this, particularly at high fields and high temperatures. The critical field data is generally well described by anisotropic Ginzburg-Landau theory which is used to calculate the coherence lengths and other parameters describing the superconductivity.

Campbell, Jorch and Thompson have corroborated the reliability of a model-based efficiency function proposed by us by applying it to their Si(Li) and Ge(Li) X-ray detectors. In the process, they did encounter a difficulty in fitting the model to the Ge(Li) detector data. The source of this difficulty is traced to unrealistic parameter signs, and its possible reoccurrence is eliminated by a simple modification of the model equation.

We develop the microscopic theory of the superconducting proximity effect to allow the calculation of the Josephson current in tunnel junctions where one or both electrodes are proximity-effect bilayers. The Josephson current can then be calculated with the same theory that is used to interpret quasiparticle tunneling characteristics in quantitative detail. One significant result is that the Josephson current is much more rapidly attenuated by thin normal layers adjacent to the tunnel barrier than is the gap in the quasiparticle current.