Third-generation Synchrotron Radiation Facility Research Articles

Propagation of synchrotron radiation through double microchannel plate device: Comparison of experimental data and wave-approach simulation

Since third-generation synchrotron radiation facilities are highly brilliant sources, the scattering of a partially coherent beam gives rise to strong interference effects. We present and discuss in this contribution the comparison of simulated and experimental diffraction patterns collected with an optical device made by two identical flat Micro Channel Plates (MCPs) illuminated by synchrotron radiation at different energies. The experimental patterns clearly show the increase of the density of the main peak with respect to those collected with a single flat MCP. Data demonstrate that the use of a device based on two MCPs is an ideal optical system to condense the primary radiation in a narrow intense central peak.

Anomalous Small-Angle X-Ray Scattering of Fuel-Cell Catalyst Samples

Anomalous small-angle X-ray scattering (ASAXS) is a technique capable of extracting element-specific structural information from multi-element materials, and is considered useful in the structure analysis of metal alloy catalyst particles for fuel cells. ASAXS utilizes the resonant term of the atomic scattering factor of the element of interest. The resonant term has a real part (f1) and an imaginary part (f2), and f1 mainly contributes to the anomalous scattering phenomenon. The amplitude of f1 varies with X-ray energy, and decreases sharply around the absorption edges of the element. The decrease is as large as -18 electrons in the case of platinum (Pt) LIII-edge. ASAXS experiments are possible only in synchrotron radiation facilities where X-ray energies are freely tunable.ASAXS experiments require X-ray recordings at 3 or more different X-ray energies to mathematically isolate the element-specific component. Although the energy dependence of f1 seems substantial at around the absorption edge, its contribution to the total scattering intensity from a multi-element system is subtle, and high-precision measurements are required to obtain correct structural information.In actual measurements, experimental errors can arise from many sources, even in present-day third-generation synchrotron radiation facilities. They include fluctuations of the X-ray beam intensities and positions, the calibration error of X-ray energies, and time-dependent changes of sample properties. Here we evaluate the effect of such errors by using model calculations. The model consists of a mixture of 3-nm Pt particles and 5-nm gold (Au) nanoparticles.The scattering profiles of this mixture were calculated for X-ray energies of 11.504, 11.555 and 11.560 keV (Curve A in Figure 1. The LIII edge is at 11.564 keV). The scattering amplitude of the Pt particles was calculated by using the f1 and f2 values from the Cromer-Liberman tables (Brennan & Cowan, Rev. Sci. Instr., 63, 1992), using equations described by Sanada et al. (J. Am. Chem. Soc., 135, 2013). The scattering from Au particles (Curve B) was assumed to be independent of energy. The extracted scattering profile for Pt was identical to that calculated for a sample with Pt particles alone (Curve D, compare with C). Next, the scattering intensities at a specific energy were deliberately changed by a few percent before extracting the Pt contribution. For intensities at 11.56 keV, even a reduction of as slight as 0.2% resulted in catastrophic consequences (Curve F). With a 5% increase of intensity, the generated Pt profile superficially looked normal, but in reality the scattering curve retained the features of the Pt-Au mixture, meaning that the Pt-specific component was not successfully extracted (Curve D).These results indicates that the accuracy requirements in ASAXS measurements are very stringent, and every effort should be made to eliminate factors that can cause errors and uncertainties.In the meeting, data recorded from actual catalyst samples will also be presented, including those from MIRAI (fuel-cell vehicle manufactured by Toyota).This work was performed under the NEDO FC-Platform project. Figure 1

Early Days of SACLA XFEL

The SACLA (SPring-8 Angstrom compact laser) was designed to significantly downsize the SASE (self-amplified spontaneous emission) type XFEL (X-ray free-electron laser), in order to generate coherent light in the wavelength region of 0.1 nm by adopting an in-vacuum undulator that can shorten the magnetic field period length. In addition, a SASE XFEL facility with a total length of 700 m has become a reality by using a C-band RF accelerating tube that enables a high acceleration gradient. Although progress was initially slow, the small-scale, low-cost SACLA was smoothly constructed, and it became the second light source to lase in the 0.1 nm wavelength region, following the LCLS (linac coherent light source) in the United States. In this paper, we look back on the history leading up to SACLA. and describe the SCSS (SPring-8 compact SASE source) project as a preparatory stage and a part of the construction/commissioning of SACLA. Since March 2012, SACLA has been operating as a shared user facility. Just a few of the upgrade activities of the facility and advanced research conducted are introduced. Finally, we will discuss the future development of the SPring-8 site, which has co-located the third-generation synchrotron radiation facility SPring-8 and the X-ray free-electron laser facility SACLA.

Ultra-brilliant GeV betatronlike radiation from energetic electrons oscillating in frequency-downshifted laser pulses.

Electrons can be accelerated to GeV energies with high collimation via laser wakefield acceleration in the bubble regime and emit bright betatron radiation in a table-top size. However, the radiation brightness is usually limited to the third-generation synchrotron radiation facilities operating at similar photon energies. Using a two-stage plasma configuration, we propose a novel scheme for generating betatronlike radiation with an extremely high brilliance. In this scheme, the relativistic electrons inside the bubble injected from the first stage can catch up with the frequency-downshifted laser pulse formed in the second stage. The laser red shift originates from the phase modulation, together with the group velocity dispersion, which enables more energy to be transfered from the laser pulse to γ-photons, giving rise to ultra-brilliant betatronlike radiation. Multi-dimensional particle-in-cell simulations indicate that the radiated γ-photons have the cut-off energy of GeV and a peak brilliance of 1026 photons s-1 mm-2 mrad-2 per 0.1%BW at 1 MeV, which may have diverse applications in various fields.

Accurate high-resolution single-crystal diffraction data from a Pilatus3 X CdTe detector.

Hybrid photon-counting detectors are widely established at third-generation synchrotron facilities and the specifications of the Pilatus3 X CdTe were quickly recognized as highly promising in charge-density investigations. This is mainly attributable to the detection efficiency in the high-energy X-ray regime, in combination with a dynamic range and noise level that should overcome the perpetual problem of detecting strong and weak data simultaneously. These benefits, however, come at the expense of a persistent problem for high diffracted beam flux, which is particularly problematic in single-crystal diffraction of materials with strong scattering power and sharp diffraction peaks. Here, an in-depth examination of data collected on an inorganic material, FeSb2, and an organic semiconductor, rubrene, revealed systematic differences in strong intensities for different incoming beam fluxes, and the implemented detector intensity corrections were found to be inadequate. Only significant beam attenuation for the collection of strong reflections was able to circumvent this systematic error. All data were collected on a bending-magnet beamline at a third-generation synchrotron radiation facility, so undulator and wiggler beamlines and fourth-generation synchrotrons will be even more prone to this error. On the other hand, the low background now allows for an accurate measurement of very weak intensities, and it is shown that it is possible to extract structure factors of exceptional quality using standard crystallographic software for data processing (SAINT-Plus, SADABS and SORTAV), although special attention has to be paid to the estimation of the background. This study resulted in electron-density models of substantially higher accuracy and precision compared with a previous investigation, thus for the first time fulfilling the promise of photon-counting detectors for very accurate structure factor measurements.

Full-field x ray nano-imaging system designed and constructed at SSRF

Full-field x ray nano-imaging (FXNI) is one of the most powerful tools for in-situ, non-destructive observation of the inner structure of samples at the nanoscale. Owing to the high flux density of the third-generation synchrotron radiation facility, great progress is achieved for FXNI and its applications. Up to now, a spatial resolution of 20 nm for FXNI is achieved. Based on the user operation experiences over the years at the Shanghai Synchrotron Radiation Facility (SSRF) x ray imaging beamline, we know lots of user experiments will rely on a large range of spatial resolutions and fields of view (FOVs). In particular, x ray microscopes with a large FOV and a moderate spatial resolution of around 100 nm have a wide range of applications in many research fields. Driven by user requirements, a dedicated FXNI system is designed and constructed at the SSRF. This microscope is based on a beam shaper and a zone plate, with the optimized working energy range set to 8–10 keV. The experimental test results by a Siemens star pattern demonstrate that a spatial resolution of 100 nm is achieved, while an FOV of 50 μm is obtained.

Diamond Light Source: status and perspectives.

Diamond Light Source, a third-generation synchrotron radiation (SR) facility in the UK, celebrated its 10th anniversary in 2012. A private limited company was set up in April 2002 to plan, construct and operate the new user-oriented SR facility, called in brief Diamond. It succeeded the Synchrotron Radiation Source in Daresbury, a second-generation synchrotron that opened in 1980 as the world's first dedicated X-ray-providing facility, closing finally in 2008, by which time Diamond's accelerators and first beamlines were operating and user experiments were under way. This theme issue of Philosophical Transactions of the Royal Society A gives some examples of the rich diversity of research done in the initial five years, with some glimpses of activity up to 2014. Speakers at the 10 year anniversary symposium were drawn from a small number of major thematic areas and each theme was elaborated by a few speakers whose contributions were placed into a broader context by a leading member of the UK academic community in the role of rapporteur. This introduction gives a summary of the design choices and strategic planning of Diamond as a coherent user facility, a snapshot of its present status and some consideration of future perspectives.

Detection of microvasculature alterations by synchrotron radiation in murine with delayed jellyfish envenomation syndrome

Using the tentacle extract (TE) from the jellyfish Cyanea capillata, we have previously established a delayed jellyfish envenomation syndrome (DJES) model, which is meaningful for clinical interventions against jellyfish stings. However, the mechanism of DJES still remains unclear. Thus, this study aimed to explore its potential mechanism by detecting TE-induced microvasculature alterations in vivo and ex vivo. Using a third-generation synchrotron radiation facility, we, for the first time, directly observed the blood vessel alterations induced by jellyfish venom in vivo and ex vivo. Firstly, microvasculature imaging of whole-body mouse in vivo indicated that the small blood vessel branches in the liver and kidney in the TE-treated group, seemed much thinner than those in the control group. Secondly, 3D imaging of kidney ex vivo showed that the kidneys in the TE-treated group had incomplete vascular trees where distal vessel branches were partly missing and disorderly disturbed. Finally, histopathological analysis found that obvious morphological changes, especially hemorrhagic effects, were also present in the TE-treated kidney. Thus, TE-induced microvasculature changes might be one of the important mechanisms of multiple organ dysfunctions in DJES. In addition, the methods we employed here will probably facilitate further studies on developing effective intervention strategies against DJES.

A Precision Grazing-incidence Angle Error Measurement of a Hard X-ray Condenser Mirror Using Single-grating Interferometry

Third-generation synchrotron radiation facilities enable us to use X-rays of extremely high brightness and low emittance, which are efficiently concentrated into a nanoscale area by a focusing device. Such progress has significantly enhanced the throughput of X-ray analyses based on scanning microscopy. On the other hand, the spatial resolution of scanning microscopy directly depends on the focal spot size. Many diffractive [1, 2], refractive [3, 4], and reflective [5, 6] focusing devices are currently available for producing small focal spots. Reflective optics realize the highest throughput with a sufficiently long working distance. Furthermore, among the above-listed focusing devices, reflective devices produce the smallest focal spot size in the hard X-ray region. A total reflection mirror may attain sub-30 nm focal spot size [7], while a multilayer mirror may attain sub-10 nm focal spot size [8]. The achievable focal spot size is significantly degraded by errors in the mirror shape and misalignment of grazing-incidence angle. In the hard X-ray region, the focusing mirror surface requires accuracies below 2 nm PV and 1 nm PV for sub-30 nm and sub-10 nm focusing, respectively. The error in the grazing-incidence angle must not exceed 0.5 × 10−6 rad and 0.1 × 10−6 rad for sub-30 nm and sub-10 nm focusing, respectively. Current advances in fabrication and mirror testing technologies have realized highly accurate deterministic figuring processes that can meet these requirements. Fabrication techniques include ion beam figuring [9, 10] and elastic emission machining (EEM) [11], while figure testing is achieved using optical interferometers [12, 13] or slope profilers [14, 15, 16]. In contrast, alignment accuracy is still evaluated by conventional beam profiling methods such as knife-edge scanning methods. The alignment is optimized by an iterative procedure of beam profiling and glazing-incidence angle adjustment. This procedure is very time-consuming and frequently introduces a significant profiling error from shape imperfections and/or vibration of the object to be scanned. Accordingly, the grazing-incidence alignment often determines the achievable focal spot size. The error in the grazing incidence angle generates a coma aberration, which is essentially a wavefront distortion with a cubic function. Hence, adjusting the grazing-incidence angle by monitoring the wavefront shape is possible. The wavefront shape can be characterized by several methods, such as phase retrieval [17] or ptychography [18, 19]. However, to obtain a wavefront shape of accuracy smaller than λ/4, the limit imposed by Rayleigh's criterion, large amounts of intensity information are required. In addition, these methods are unsuitable for the shot-by-shot measurements demanded in X-ray free-electron laser (XFEL) focusing.

High Energy X-ray Micro-tomography for the characterization of thermally fatigued GlidCop specimen

The expected increases in the thermal power of X-ray beams produced at the third-generation synchrotron radiation facilities may exceed the heat-load capabilities of the existing high-heat-load components with which the beams interact. An X-ray beam shutter is an example of such components. Typically made of GlidCop, it is used, as needed, to block the X-ray beam from entering the experimental area. Analyses show that the planned 50% increase in storage ring beam current (and thus beam heat load) at the Advanced Photon Source (APS) will result in plastic strain in the shutter limiting its operational life. In order to develop a predictive model to estimate the number of cycles to failure, cooled GlidCop samples were thermally cycled 10,000 times under the high heat load of an X-ray beam from two inline APS undulators. Samples are examined for cracks, and crack size information is extracted for use in the model. In this paper, following some introductory remarks, we report on the characterization of the micron-size fatigue cracks in a sample GlidCop using high-energy X-ray absorption and phase-contrast tomography. It is shown that the current set up at beamline 1-ID at the APS is capable of nondestructive reconstruction of internal structure of the fatigued part with a resolution of 3 μm, which may further be improved to about 1 μm.

Recent Progress of the X-ray Magnetic Circular Dichroism Technique for Element-Specific Magnetic Analysis

Recent trend of the X-ray magnetic circular dichroism (XMCD) spectroscopy-based technique and the related scientific topics at SPring-8 are reviewed. At the third-generation synchrotron radiation facility, the key developments in the XMCD technique include i) significant improvements in the accuracy and sensitivity of XMCD measurements with a quick helicity switching of circularly polarized X-rays, ii) introduction of extreme conditions (strong pulsed magnetic field and high pressures), and iii) new experimental setup using the high-brilliance X-ray source (micro-focusing, reflection geometry, and high-pressure cells). These achievements have effectively extended the capability of the XMCD technique, a unique magnetic probe with an element-specificity, providing fundamental scientific insights in spintronics and magnetic recording devices, magnetic nanoparticles, and magnetism under high-magnetic field and high pressures.

Inelastic X-ray Scattering Studies of Electronic Excitations

Inelastic x-ray scattering (IXS) has developed into one of the most powerful momentum-resolved spectroscopies. Especially in the last decade, it has achieved significant progress utilizing brilliant x-rays from third-generation synchrotron radiation facilities. Simultaneously, theoretical efforts have been made to predict or interpret the experimental spectra. One of the scientific fields studied intensively by IXS is strongly correlated electron systems, where the interplay of charge, spin, and orbital degrees of freedom determines their physical properties. IXS can provide a new insight into the electron dynamics of the systems through the observation of charge, spin, and orbital excitations. Focusing on the momentum-resolved electronic excitations in strongly correlated electron systems, we review IXS studies and the present capabilities of IXS for the study of the dynamics of materials. With nonresonant inelastic x-ray scattering (NIXS), one can directly obtain dynamical charge correlation and we disc...

Anomalous X-ray scattering studies on semiconducting and metallic glasses

In order to explore local- and intermediate-range atomic structures of several semiconducting and metallic glasses, anomalous X-ray scattering (AXS) experiments were performed using an improved detecting system suitable for third-generation synchrotron radiation facilities, and the obtained data were analyzed using reverse Monte Carlo (RMC) modelling to obtain partial structure factors and to construct three-dimensional atomic configurations of these glasses. Examples of GeSe2 semiconducting and Pd40Ni40P20 metallic glasses are demonstrated to exhibit the feasibility of the combination of AXS and RMC techniques. Importance of an additional combination with neutron scattering is also described for alloys containing light elements.

Detection and visualisation of elemental components in various ambient species by synchrotron microbeam technique

This study introduces the application of the synchrotron radiation induced X-ray fluorescence (SR-XRF) microprobe installed at the Super Photon ring-8 GeV (SPring-8), which is the world's largest third-generation synchrotron radiation facility, to the specification of chemical properties of various atmospheric samples. The combination of visual elemental mapping and XRF spectral analyses allows for the interpretation of the nature and composition of individual particles. Individually collected droplets by the replication technique were also irradiated by X-ray microbeam to carry out visual reconstruction of elemental maps for their multiple components. The multielemental peaks corresponding to X-ray energy were also successfully resolved. Because the chemical contents of solute for individual droplets can be definitely clarified in this study, we can describe the mechanisms involved in droplet formation and pollutant scavenging. The point analysis of sand dust collected from the local desert in China confirmed that the fine fragments of sand, which may be lifted and transported over a long distance, are considerably inhomogeneous in elemental component.

P2-10-05: Cryo-Microcomputed Tomography (CT) with Synchrotron Radiation: Visualization of Human Breast Cancer Tissue and Comparison with Their Histopathologic Findings.

Abstract Background: A synchrotron radiation (SR)-based X-ray source offers a powerful tool for diagnosis of breast disease due to the energy spectrum properties and the peculiar laminar beam geometry. The aims of this study were to estimate the visualization of the human breast cancer tissue with SR cryo-micro CT and to compare the results with histopathological examinations. Material and Methods: The cancerous breast tissue samples were routinely fixed in 10% neutral buffered formalin, and each specimen was cut down to a cylindrical sample with 2 mm diameter and 10 mm height. Each breast cancer sample was rapidly frozen with dry ice, mounted on a computer-controlled precision stage and maintained at cryogenic temperature throughout data collection. Experiments were performed at the bending magnet beamline 7B2 of Pohang Light Source (PLS) in Accelerator Laboratory (PAL) which is a third-generation SR facility with 2.5 GeV operating energy. The white beam imaging system developed for synchrotron tomography consists of a 1 mm Si attenuator, 100 μm-thick CdWO4 scintillator and a full-frame charge-coulped device camera. The detector is placed 10 mm downstream from the sample on an optical table which can be rotated in the fan beam about a vertical axis for tomography. For tomography, images were collected at 0.18° increments through 180°. The visual image was magnified using a 20x microscope objective and captured using a digital CCD camera. The spatial resolution determined by standard sample was about 1.5 μm. Three-dimensional volume images of the specimen were obtained by applying a filtered back-projection algorithm to the projection images using a software package OCTOPUS. Surface reconstruction and volume segmentation and rendering were performed using Amira software. After imaging the samples were split into several sections, processed and embedded in paraffin. Obtained tomography images were compared with corresponding histopathological findings in optical microscopy. Results: A total of 1000 synchrotron tomography images were acquired from the samples and only a small number of different typical cases were selected for a detailed analysis. The correspondence between tomography images and histopathological findings were determined. Synchrotron tomography images yield high contrast from smoothly varying internal structures corresponding to information on actual structures seen at histopathological analysis. Discussion: Since the projection of 3D anatomic information onto 2D image will complicate subtle difference in X-ray transmission and objects at different depths will be superimposed on each other, the subtle difference in subject attenuation, diffraction and contrast may not be clearly visible or completely lost. Tomography with SR has superior visualization of subject contrast, together with depth localization, so it is useful for visualizing anatomical structures in the sample. In this study, the obtained SR cryo-micro CT images of human breast cancer tissue were comparable with standard histopathologic findings. The results suggest that tomography with SR has a great potential as a diagnostic tool and also its clinical application is feasible, especially in breast imaging. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-10-05.

Feasibility of in-line instruments for high-resolution inelastic X-ray scattering

Inelastic X-ray scattering instruments in operation at third-generation synchrotron radiation facilities are based on backreflections from perfect silicon crystals. This concept reaches back to the very beginnings of high-energy-resolution X-ray spectroscopy and has several advantages but also some inherent drawbacks. In this paper an alternate path is investigated using a different concept, the `M(4) instrument'. It consists of a combination of two in-line high-resolution monochromators, focusing mirrors and collimating mirrors. Design choices and performance estimates in comparison with existing conventional inelastic X-ray scattering instruments are presented.

Front-end design of National Synchrotron Light Source II

National Synchrotron Light Source II (NSLS-II) will be a 3-GeV, 792-m circumference third-generation synchrotron radiation facility with ultralow emittance and extremely high brightness. Front ends are required to transmit synchrotron radiation from the storage ring to the beam line while providing equipment and personnel protection. There will be up to 57 front ends in the NSLS-II facility with six in the baseline. Original designs are being developed and will be manufactured for three non-canted in-vacuum undulators, one canted in-vacuum undulator, one elliptically polarized undulator and one damping wiggler. Bending magnet and three-pole wiggler front ends are also being designed. Power densities range from 0.3 to 89.8 kW mrad−2, with total powers ranging from 0.34 to 64.5 kW. All components intercepting synchrotron radiation are water cooled and were analysed to confirm acceptable thermal limits.

Operational radiation protection in synchrotron light and free electron laser facilities

The third-generation synchrotron radiation (SR) facilities are storage ring-based facilities with many insertion devices and photon beamlines, and have low injection beam power, but extremely high stored beam power. The fourth-generation X-ray free electron laser (FEL) facilities are based on an electron Linac with a long undulator and have high injection beam power. Due to its electron and photon beam characteristics and modes of operation, storage ring and photon beamlines have unique safety aspects, which are the main subjects of this paper. The shielding design limits, operational modes and beam losses are reviewed. Shielding analysis (source terms and methodologies) and interlocked safety systems for storage ring and photon beamlines (including SR and gas bremsstrahlung) are described. Specific safety issues for storage ring top-off injection and FEL facilities are discussed. Operational safety programme elements, e.g. operation authorisation, commissioning, training and radiation measurements, for SR facilities are also presented.

Field-free molecular alignment for studies using x-ray pulses from a synchrotron radiation source

A short, intense laser pulse may be employed to create a spatially aligned molecular sample that persists after the laser pulse is over. We theoretically investigate whether this impulsive molecular alignment technique may be exploited for experiments using x-ray pulses from a third-generation synchrotron radiation facility. Using a linear rigid rotor model, the alignment dynamics of model molecular systems with systematically increasing size is calculated utilizing both a quantum density matrix formalism and a classical ensemble method. For each system, the alignment dynamics obtained for a 95 ps laser is compared with that obtained for a 10 ps laser pulse. The average degree of alignment after the laser pulse, as calculated quantum mechanically, increases with the size of the molecule. This effect is quantitatively reproduced by the classical calculations. The average degree of impulsive alignment is high enough to induce a pronounced linear dichroism in resonant x-ray absorption using the intense 100 ps x-ray pulses currently available. However, for structural studies based on elastic x-ray scattering, bright x-ray pulses with a duration of 1 ps or shorter will be required in order to make full use of impulsive molecular alignment.

Increasing Preload Reduced Actin-Myosin Interaction in Isolated Beating Rat Whole Heart Under Hypoxia

Background: Hypoxia reduces cardiac contractile performance. However, there is no direct observation on how preload affects the actinmyosin-interaction (AMI) in beating hearts during hypoxia. Purpose: The aim of this study is to investigate this theme using X-ray-diffraction (XRD) analysis at a third-generation synchrotron radiation facility. Methods: Eight isolated isovolumically contracting rat hearts were paced at 120 bpm after complete heart block, mounted so that the X-ray beam (15.0 keV) passed the deeper layer of left ventricular (LV) free wall, and perfused with Tyrode solution bubbled with 100%O2(Normo) or 100%N2(Hypo). We recorded XRD patterns and LV pressure (LVP) at end-diastolic LVP (EDP) of 0 and 20 mmHg. Results: Under Normo, increasing EDP significantly increased the developed-LVP (EDP0: 104±26mmHg vs. EDP20: 141±25mmHg, p<0.01). Under Hypo, developed LVP and its duration did not show significant differences compared with those in Normo. However, increasing EDP under Hypo significantly decreased developed LVP (72±13mmHg vs. 96±16mmHg, p<0.01). The minimum value of the (1,0)/(1,1) intensity ratio (Imin) provided by the XRD analysis was used as an index of AMI. Imin showed a significantly negative correlation with developed LVP regardless of Normo or Hypo. The diastolic myosin filament lattice spacing (MFL) calculated from the diffraction angle of the (1,0) equatorial reflection would be reduced by increasing EDP. In contrast to a significantly positive MFL-Imin correlation under Normo, we observed the significantly negative MFL-Imin correlation under Hypo. We confirmed that the duration of Ca2 + transient was slightly longer but the amplitude of Ca2 + transient was unchanged under Hypo. Conclusion: These novel findings suggest that under Hypo the probability of AMI decreases even though the MFL was reduced with increasing preload. This is an underlyingmechanism for reduced cardiac contractile performance under hypoxia.