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1
Yuan, Chao, Riley Hanus, and Samuel Graham. "A review of thermoreflectance techniques for characterizing wide bandgap semiconductors’ thermal properties and devices’ temperatures." Journal of Applied Physics 132, no. 22 (December 14, 2022): 220701. http://dx.doi.org/10.1063/5.0122200.
Анотація:
Thermoreflectance-based techniques, such as pump–probe thermoreflectance (pump–probe TR) and thermoreflectance thermal imaging (TTI), have emerged as the powerful and versatile tools for the characterization of wide bandgap (WBG) and ultrawide bandgap (UWBG) semiconductor thermal transport properties and device temperatures, respectively. This Review begins with the basic principles and standard implementations of pump–probe TR and TTI techniques, illustrating that when analyzing WBG and UWBG materials or devices with pump–probe TR or TTI, a metal thin-film layer is often required. Due to the transparency of the semiconductor layers to light sources with sub-bandgap energies, these measurements directly on semiconductors with bandgaps larger than 3 eV remain challenging. This Review then summarizes the general applications of pump–probe TR and TTI techniques for characterizing WBG and UWBG materials and devices where thin metals are utilized, followed by introducing more advanced approaches to conventional pump–probe TR and TTI methods, which achieve the direct characterizations of thermal properties on GaN-based materials and the channel temperature on GaN-based devices without the use of thin-film metals. Discussions on these techniques show that they provide more accurate results and rapid feedback and would ideally be used as a monitoring tool during manufacturing. Finally, this Review concludes with a summary that discusses the current limitations and proposes some directions for future development.
2
Zhong, Haoyuan, Changhua Bao, Tianyun Lin, Shaohua Zhou, and Shuyun Zhou. "A newly designed femtosecond KBe2BO3F2 device with pulse duration down to 55 fs for time- and angle-resolved photoemission spectroscopy." Review of Scientific Instruments 93, no. 11 (November 1, 2022): 113910. http://dx.doi.org/10.1063/5.0106864.
Анотація:
Developing a widely tunable vacuum ultraviolet (VUV) source with a sub-100 fs pulse duration is critical for ultrafast pump–probe techniques such as time- and angle-resolved photoemission spectroscopy (TrARPES). While a tunable probe source with a photon energy of 5.3–7.0 eV has been recently implemented for TrARPES by using a KBe2BO3F2 (KBBF) device, the time resolution of 280–320 fs is still not ideal, which is mainly limited by the duration of the VUV probe pulse generated by the KBBF device. Here, by designing a new KBBF device, which is specially optimized for fs applications, an optimum pulse duration of 55 fs is obtained after systematic diagnostics and optimization. More importantly, a high time resolution of 81–95 fs is achieved for TrARPES measurements covering the probe photon energy range of 5.3–7.0 eV, making it particularly useful for investigating the ultrafast dynamics of quantum materials. Our work extends the application of the KBBF device to ultrafast pump–probe techniques with the advantages of both a widely tunable VUV source and ultimate time resolution.
3
Nango, Eriko, Minoru Kubo, Kensuke Tono, and So Iwata. "Pump-Probe Time-Resolved Serial Femtosecond Crystallography at SACLA: Current Status and Data Collection Strategies." Applied Sciences 9, no. 24 (December 14, 2019): 5505. http://dx.doi.org/10.3390/app9245505.
Анотація:
Structural information on protein dynamics is a critical factor in fully understanding the protein functions. Pump-probe time-resolved serial femtosecond crystallography (TR-SFX) is a recently established technique for visualizing the structural changes or reactions in proteins that are at work with high spatial and temporal resolution. In the pump-probe method, protein microcrystals are continuously delivered from an injector and exposed to an X-ray free-electron laser (XFEL) pulse after a trigger to initiate a reaction, such as light, chemicals, temperature, and electric field, which affords the structural snapshots of intermediates that occur in the protein. We are in the process of developing the device and techniques for pump-probe TR-SFX while using XFEL produced at SPring-8 Angstrom Compact Free-Electron Laser (SACLA). In this paper, we described our current development details and data collection strategies for the optical pump X-ray probe TR-SFX experiment at SACLA and then reported the techniques of in crystallo TR spectroscopy, which is useful in clarifying the nature of reaction that takes place in crystals in advance.
4
Kubo, Minoru, Eriko Nango, Kensuke Tono, Tetsunari Kimura, Shigeki Owada, Changyong Song, Fumitaka Mafuné, et al. "Nanosecond pump–probe device for time-resolved serial femtosecond crystallography developed at SACLA." Journal of Synchrotron Radiation 24, no. 5 (August 22, 2017): 1086–91. http://dx.doi.org/10.1107/s160057751701030x.
Анотація:
X-ray free-electron lasers (XFELs) have opened new opportunities for time-resolved X-ray crystallography. Here a nanosecond optical-pump XFEL-probe device developed for time-resolved serial femtosecond crystallography (TR-SFX) studies of photo-induced reactions in proteins at the SPring-8 Angstrom Compact free-electron LAser (SACLA) is reported. The optical-fiber-based system is a good choice for a quick setup in a limited beam time and allows pump illumination from two directions to achieve high excitation efficiency of protein microcrystals. Two types of injectors are used: one for extruding highly viscous samples such as lipidic cubic phase (LCP) and the other for pulsed liquid droplets. Under standard sample flow conditions from the viscous-sample injector, delay times from nanoseconds to tens of milliseconds are accessible, typical time scales required to study large protein conformational changes. A first demonstration of a TR-SFX experiment on bacteriorhodopsin in bicelle using a setup with a droplet-type injector is also presented.
5
Guiraudon, Gerard M., Douglas L. Jones, Daniel Bainbridge, John T. Moore, Chris Wedlake, Cristian Linte, Andrew Wiles, and Terry M. Peters. "Off-Pump Atrial Septal Defect Closure Using the Universal Cardiac Introducer®." Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery 4, no. 1 (January 2009): 20–26. http://dx.doi.org/10.1097/imi.0b013e31819878f2.
Анотація:
Objective Optimal atrial septal defect (ASD) closure should combine off-pump techniques with the effectiveness and versatility of open-heart techniques. We report our experience with off-pump ASD closure using the Universal Cardiac Introducer (UCI) in a porcine model. The goal was to create an ASD over the fossa ovale (FO) and position a patch over the ASD under ultrasound (US) imaging and augmented virtual reality guidance. Methods An US probe (tracked with a magnetic tracking system) was positioned into the esophagus (transesophageal echocardiographic probe) for real-time image-guidance. The right atrium (RA) of six pigs was exposed via a right lateral thoracotomy or medial sternotomy. The UCI was attached to the RA wall. A punching tool was introduced via the UCI, navigated and positioned, under US guidance, to create an ASD into the FO. A patch with its holder and a stapling device were introduced into the RA via the UCI. The patch was positioned on the ASD. Occlusion of the ASD was determined using US and Doppler imaging. Results The FO membrane was excised successfully in all animals. US image-guidance provided excellent visualization. The patch was positioned in all cases with complete occlusion of the ASD. The stapling device proved too bulky, impeding circumferential positioning. Conclusions Using the UCI, ASD closure was safe and feasible. US imaging, combined with virtual and augmented reality provided accurate navigating and positioning. This study also provided valuable information on the future design of anchoring devices for intracardiac procedures.
6
Wang, Cong, Lingfeng Gao, Hualong Chen, Yiquan Xu, Chunyang Ma, Haizi Yao, Yufeng Song, and Han Zhang. "Broadband and ultrafast all-optical switching based on transition metal carbide." Nanophotonics 10, no. 10 (June 25, 2021): 2617–23. http://dx.doi.org/10.1515/nanoph-2021-0066.
Анотація:
Abstract Ultrafast all-optical switches have attracted considerable attention for breaking through the speed limitation of electric devices. However, ultrafast and high-efficiency all-optical switches based on two-dimensional (2D) materials can be achieved due to their strong nonlinear optical response and ultrafast carrier dynamic. For this reason, we propose the pump-probe method to achieve an ultrafast optical switcher with a response time of 192 fs and a switching energy of 800 nJ by using transition metal carbide (Nb2C). The response time and switching energy are far smaller than that of the all-optical device based on the saturable absorption effect of 2D materials. It is believed that the Nb2C-based all-optical switch provides a novel idea to achieve a high-performance all-optical device and has the potential for application in high-speed photonics processing.
7
Lim, Swee Sien, David Giovanni, Qiannan Zhang, Ankur Solanki, Nur Fadilah Jamaludin, Jia Wei Melvin Lim, Nripan Mathews, Subodh Mhaisalkar, Maxim S. Pshenichnikov, and Tze Chien Sum. "Hot carrier extraction in CH3NH3PbI3 unveiled by pump-push-probe spectroscopy." Science Advances 5, no. 11 (November 2019): eaax3620. http://dx.doi.org/10.1126/sciadv.aax3620.
Анотація:
Halide perovskites are promising materials for development in hot carrier (HC) solar cells, where the excess energy of above-bandgap photons is harvested before being wasted as heat to enhance device efficiency. Presently, HC separation and transfer processes at higher-energy states remain poorly understood. Here, we investigate the excited state dynamics in CH3NH3PbI3 using pump-push-probe spectroscopy. It has its intrinsic advantages for studying these dynamics over conventional transient spectroscopy, albeit complementary to one another. By exploiting the broad excited-state absorption characteristics, our findings reveal the transfer of HCs from these higher-energy states into bathophenanthroline (bphen), an energy selective organic acceptor far above perovskite’s band edges. Complete HC extraction is realized only after overcoming the interfacial barrier formed at the heterojunction, estimated to be between 1.01 and 1.08 eV above bphen’s lowest unoccupied molecular orbital level. The insights gained here are essential for the development of a new class of optoelectronics.
8
Sander, Mathias, Roman Bauer, Victoria Kabanova, Matteo Levantino, Michael Wulff, Daniel Pfuetzenreuter, Jutta Schwarzkopf, and Peter Gaal. "Demonstration of a picosecond Bragg switch for hard X-rays in a synchrotron-based pump–probe experiment." Journal of Synchrotron Radiation 26, no. 4 (June 12, 2019): 1253–59. http://dx.doi.org/10.1107/s1600577519005356.
Анотація:
A benchmark experiment is reported that demonstrates the shortening of hard X-ray pulses in a synchrotron-based optical pump–X-ray probe measurement. The pulse-shortening device is a photoacoustic Bragg switch that reduces the temporal resolution of an incident X-ray pulse to approximately 7.5 ps. The Bragg switch is employed to monitor propagating sound waves in nanometer thin epitaxial films. From the experimental data, the pulse duration, diffraction efficiency and switching contrast of the device can be inferred. A detailed efficiency analysis shows that the switch can deliver up to 109 photons s−1 in high-repetition-rate synchrotron experiments.
9
Johnson, Howard D., Marc S. Morgan, and Joe R. Utley. "Use of the Cell Saver as a Rapid Infusion Device." Journal of ExtraCorporeal Technology 21, no. 3 (September 1989): 96–99. http://dx.doi.org/10.1051/ject/198921396.
Анотація:
A Bio-Medicus pump with a model BP 80, flow probe, model DP 38, and Gott TDMAC Shunt tubing, primed with Plasma Lyte A, pH 7.4, was used during a repair of a descending aortic aneurysm. The Haemonetic Cell Saver Plus with 1/4" tubing, List #243, and Gish Cardiotomy ATR-2900F was used to process shed blood. The patient was heparinized with 31,000 units of beef lung heparin (400 units/Kg) to maintain the activated clotting time above 480 seconds. The aneurysm was opened. Collateral bleeding caused the patient to bleed out excessively into the cell saver, rendering the Bio-Pump ineffective due to severe hypovolemia. As the bleeding was controlled, the cell saver was connected to the Gott TDMAC shunt tubing with a 1/4" X 3/8" connector to autotransfuse shed blood from the cardiotomy back to the patient, bypassing the cell saver centrifuge. The aortic cross clamp time was 22 minutes. The patient suffered no complications and at the 12 month follow up, she continues to do well. In summary, we feel that the surgical team should be equipped to provide ancillary support as the situation requires.
10
Zaman, Abdullah M., Yuichi Saito, Yuezhen Lu, Farhan Nur Kholid, Nikita W. Almond, Oliver J. Burton, Jack Alexander-Webber, et al. "Ultrafast modulation of a THz metamaterial/graphene array integrated device." Applied Physics Letters 121, no. 9 (August 29, 2022): 091102. http://dx.doi.org/10.1063/5.0104780.
Анотація:
We report on the ultrafast modulation of a graphene loaded artificial metasurface realized on a SiO2/Si substrate by near-IR laser pump, detected via terahertz probe at the resonant frequency of ∼0.8 THz. The results have been acquired by setting the Fermi energy of graphene at the Dirac point via electrostatic gating and illuminating the sample with 40 fs pump pulses at different fluences, ranging from 0.9 to 0.018 mJ/cm2. The sub-ps conductivity rising time was attributed to the combined effect of the ultrafast generation of hot carriers in graphene and electron–hole generation in silicon. In correspondence of the resonance, it was possible to clearly distinguish a partial recovery time of ∼2 ps mainly due to carrier-phonon relaxation in graphene, superimposed to the > 1 ns recovery time of silicon. The resonant metasurface yielded ∼6 dB modulation depth in E-field amplitude at 0.8 THz for the range of fluences considered. These measurements set an upper limit for the reconfiguration speed achievable by graphene-based terahertz devices. At the same time, this work represents a great progress toward the realization of an ultrafast THz optoelectronic platform for a plethora of applications, ranging from the investigation of the ultrastrong light-matter regime to the next generation wireless communications.
11
Kang, Tongtong, Zongwei Ma, Jun Qin, Zheng Peng, Weihao Yang, Taixing Huang, Shilin Xian, et al. "Large-scale, power-efficient Au/VO2 active metasurfaces for ultrafast optical modulation." Nanophotonics 10, no. 2 (November 17, 2020): 909–18. http://dx.doi.org/10.1515/nanoph-2020-0354.
Анотація:
AbstractActive metasurfaces, in which the optical property of a metasurface device can be controlled by external stimuli, have attracted great research interest recently. For optical switching and modulation applications, high-performance active metasurfaces need to show high transparency, high power efficiency, as well as ultrafast switching and large-scale fabrication capability. This paper reports Au/VO2-based active metasurfaces meeting the requirements above. Centimeter-scale Au/VO2 metasurfaces are fabricated by polystyrene sphere colloidal crystal self-assembly. The devices show optical modulation on-off ratio up to 12.7 dB and insertion loss down to 3.3 dB at 2200 nm wavelength in the static heating experiment, and ΔT/T of 10% in ultrafast pump-probe experiments. In particular, by judiciously aligning the surface plasmon resonance wavelength to the pump wavelength of the femtosecond laser, the enhanced electric field at 800 nm is capable to switch off the extraordinary optical transmission effect at 2200 nm in 100 fs time scale. Compared to VO2 thin-film samples, the devices also show 50% power reduction for all-optical modulation. Our work provides a practical way to fabricate large-scale and power-efficient active metasurfaces for ultrafast optical modulation.
12
Margheri, Giancarlo, André Nascimento Barbosa, Fernando Lazaro Freire, and Tommaso Del Rosso. "Thermooptical PDMS-Single-Layer Graphene Axicon-like Device for Tunable Submicron Long Focus Beams." Micromachines 13, no. 12 (November 26, 2022): 2083. http://dx.doi.org/10.3390/mi13122083.
Анотація:
Submicron long focusing range beams are gaining attention due to their potential applications, such as in optical manipulation, high-resolution lithography and microscopy. Here, we report on the theoretical and experimental characterization of an elastomeric polydimethylsiloxane/single layer graphene (PDMS/SLG) axicon-like tunable device, able to generate diffraction-resistant submicrometric spots in a pump and probe configuration. The working principle is based on the phase change of an input Gaussian beam induced in the elastomer via the thermo-optical effect, while the heating power is produced by the optical absorption of the SLG. The phase-modified beam is transformed by an objective into a long focus with submicron diameter. Our foci reach an experimental full width at half maximum (FWHM) spot diameter of 0.59 μm at the wavelength of 405 nm, with the FWHM length of the focal line greater than 90 μm. Moreover, the length of the focal line and the diameter of the focus can be easily tuned by varying the pump power. The proposed thermo-optical device can thus be useful for the simple and cheap improvement of the spatial resolution on long focus lines.
13
Baldwin, J. T., J. M. Tarbell, S. Deutsch, D. B. Geselowitz, and G. Rosenberg. "Hot-Film Wall Shear Probe Measurements Inside a Ventricular Assist Device." Journal of Biomechanical Engineering 110, no. 4 (November 1, 1988): 326–33. http://dx.doi.org/10.1115/1.3108449.
Анотація:
Wall shear rates at eleven sites within the Penn State Electric Ventricular Assist Device (EVAD) were determined with the pump operating under conditions of 30 and 50 percent systolic duration and a mean flow rate of 5.8 L/min using a flush-mounted hot-film probe. Probe calibrations were performed with the hot-film in two orientations relative to the flow direction: a standard orientation and an orientation in which the hot-film was rotated by 90 deg from the standard orientation. The magnitude and direction of the wall shear stress at each site within the EVAD were estimated from ensemble averaged voltage data recorded for similar standard and rotated film orientations. The results indicate that, during diastole the wall shear stress direction around the pump’s periphery for both operating conditions is predominantly perpendicular to the inflow-outflow plane (in the direction of the pusher plate motion) and reaches a peak value of approximately 350 dynes/cm2. The highest wall shear stresses were found near the prosthetic aortic valve (inside the EVAD) under the 30 percent systolic duration condition and are estimated to be as high as 2700 dynes/cm2. Peak shear stress values of 1400 dynes/cm2 were observed in the vicinity of the prosthetic mitral valve under both operating conditions. The results suggested that the valve regions are substantially more hemolytic than other wall regions of the EVAD; the magnitudes of the wall shear stresses are sensitive to operating conditions; and that wall shear in the direction of pusher plate motion can be significant.
14
Ramanathan, Shriram, and David G. Cahill. "High-resolution picosecond acoustic microscopy for non-invasive characterization of buried interfaces." Journal of Materials Research 21, no. 5 (May 1, 2006): 1204–8. http://dx.doi.org/10.1557/jmr.2006.0141.
Анотація:
Non-destructive investigation of buried interfaces at high-resolution is critical for integrated circuit and advanced packaging research and development. In this letter, we present a novel non-contact microscopy technique using ultrahigh frequency (GHz range) longitudinal acoustic pulses to form images of interfaces and layers buried deep inside a silicon device. This method overcomes fundamental limitations of conventional scanning acoustic microscopy by directly generating and detecting the acoustic waves on the surface of the sample using an ultrafast pump-probe optical technique. We demonstrate our method by imaging copper lines buried beneath a 6-μm silicon wafer; the lateral spatial resolution of 3 μm is limited by the laser spot size. In addition to the high lateral spatial resolution, the technique has picosecond (ps) time resolution and therefore will enable imaging individual interconnect layers in multi-layer stacked devices.
15
Yue, Shuai, Fei Tian, Xinyu Sui, Mohammadjavad Mohebinia, Xianxin Wu, Tian Tong, Zhiming Wang, et al. "High ambipolar mobility in cubic boron arsenide revealed by transient reflectivity microscopy." Science 377, no. 6604 (July 22, 2022): 433–36. http://dx.doi.org/10.1126/science.abn4727.
Анотація:
Semiconducting cubic boron arsenide (c-BAs) has been predicted to have carrier mobility of 1400 square centimeters per volt-second for electrons and 2100 square centimeters per volt-second for holes at room temperature. Using pump-probe transient reflectivity microscopy, we monitored the diffusion of photoexcited carriers in single-crystal c-BAs to obtain their mobility. With near-bandgap 600-nanometer pump pulses, we found a high ambipolar mobility of 1550 ± 120 square centimeters per volt-second, in good agreement with theoretical prediction. Additional experiments with 400-nanometer pumps on the same spot revealed a mobility of >3000 square centimeters per volt-second, which we attribute to hot electrons. The observation of high carrier mobility, in conjunction with high thermal conductivity, enables an enormous number of device applications for c-BAs in high-performance electronics and optoelectronics.
16
Shimazu, Yoshiaki, Kensuke Tono, Tomoyuki Tanaka, Yasuaki Yamanaka, Takanori Nakane, Chihiro Mori, Kanako Terakado Kimura, et al. "High-viscosity sample-injection device for serial femtosecond crystallography at atmospheric pressure." Journal of Applied Crystallography 52, no. 6 (October 17, 2019): 1280–88. http://dx.doi.org/10.1107/s1600576719012846.
Анотація:
A sample-injection device has been developed at SPring-8 Angstrom Compact Free-Electron Laser (SACLA) for serial femtosecond crystallography (SFX) at atmospheric pressure. Microcrystals embedded in a highly viscous carrier are stably delivered from a capillary nozzle with the aid of a coaxial gas flow and a suction device. The cartridge-type sample reservoir is easily replaceable and facilitates sample reloading or exchange. The reservoir is positioned in a cooling jacket with a temperature-regulated water flow, which is useful to prevent drastic changes in the sample temperature during data collection. This work demonstrates that the injector successfully worked in SFX of the human A2A adenosine receptor complexed with an antagonist, ZM241385, in lipidic cubic phase and for hen egg-white lysozyme microcrystals in a grease carrier. The injection device has also been applied to many kinds of proteins, not only for static structural analyses but also for dynamics studies using pump–probe techniques.
17
Ezgi Eroglu, Zeynep, Dillon Contreras, Pouya Bahrami, Nurul Azam, Masoud Mahjouri-Samani, and Abdelaziz Boulesbaa. "Filling Exciton Trap-States in Two-Dimensional Tungsten Disulfide (WS2) and Diselenide (WSe2) Monolayers." Nanomaterials 11, no. 3 (March 18, 2021): 770. http://dx.doi.org/10.3390/nano11030770.
Анотація:
Two-dimensional transition metal dichalcogenides (2D-TMDs) hold a great potential to platform future flexible optoelectronics. The beating hearts of these materials are their excitons known as XA and XB, which arise from transitions between spin-orbit split (SOS) levels in the conduction and valence bands at the K-point. The functionality of 2D-TMD-based devices is determined by the dynamics of these excitons. One of the most consequential channels of exciton decay on the device functionality is the defect-assisted recombination (DAR). Here, we employ steady-state absorption and emission spectroscopies, and pump density-dependent femtosecond transient absorption spectroscopy to report on the effect of DAR on the lifetime of excitons in monolayers of tungsten disulfide (2D-WS2) and diselenide (2D-WSe2). These pump-probe measurements suggested that while exciton decay dynamics in both monolayers are driven by DAR, in 2D-WS2, defect states near the XB exciton fill up before those near the XA exciton. However, in the 2D-WSe2 monolayer, the defect states fill up similarly. Understanding the contribution of DAR on the lifetime of excitons and the partition of this decay channel between XA and XB excitons may open new horizons for the incorporation of 2D-TMD materials in future optoelectronics.
18
Ščajev, Patrik, Saulius Miasojedovas, Martyna Mazuronytė, Liuwen Chang, and Mitch M. C. Chou. "Magnesium zinc oxide detectors for fast ultraviolet detection." Journal of Applied Physics 132, no. 14 (October 14, 2022): 144501. http://dx.doi.org/10.1063/5.0108890.
Анотація:
We explored a Mg-alloyed ZnO material (or MgZnO alloy) on a lattice-matched scandium aluminum magnesium oxide substrate for obtaining most effective photodetectors with highest (∼10 A/W) and fastest (up to 3 GHz) responses and two orders of magnitude UV/VIS rejection ratio. Device operation was related to its material electronic properties (carrier lifetime, diffusivity, and diffusion length) via photoluminescence and light-induced pump–probe techniques. Defect-related response is found suitable for sensitive logarithmic detectors, while exciton-related response is favorable to ultrafast linear UV solar blind detectors. Two-contact planar detector design allows their application in low-cost environmental detection systems.
19
Hertlein, M. P., A. Scholl, A. A. Cordones, J. H. Lee, K. Engelhorn, T. E. Glover, B. Barbrel, et al. "X-rays only when you want them: optimized pump–probe experiments using pseudo-single-bunch operation." Journal of Synchrotron Radiation 22, no. 3 (April 2, 2015): 729–35. http://dx.doi.org/10.1107/s1600577515001770.
Анотація:
Laser pump–X-ray probe experiments require control over the X-ray pulse pattern and timing. Here, the first use of pseudo-single-bunch mode at the Advanced Light Source in picosecond time-resolved X-ray absorption experiments on solutions and solids is reported. In this mode the X-ray repetition rate is fully adjustable from single shot to 500 kHz, allowing it to be matched to typical laser excitation pulse rates. Suppressing undesired X-ray pulses considerably reduces detector noise and improves signal to noise in time-resolved experiments. In addition, dose-induced sample damage is considerably reduced, easing experimental setup and allowing the investigation of less robust samples. Single-shot X-ray exposures of a streak camera detector using a conventional non-gated charge-coupled device (CCD) camera are also demonstrated.
20
Ratty, Susan C., Mary Winkler, John Lamberti, and Ricardo Moreno-Cabral. "Ventricular Assist in the Infant." Journal of ExtraCorporeal Technology 22 (1990): 62–65. http://dx.doi.org/10.1051/ject/199022s062.
Анотація:
Two cases are described in which the Bio-Medicus centrifugal pump is used to support ventricular failure post CPB in the infant patient. The first patient (5 kg) was diagnosed with anomalous left coronary artery and pre-operative myocardial infarction. This patient required left ventricular assist support for 70 hours following surgical repair and failure to wean from CPB. The second patient (5 kg) presented 12 days status post mustard procedure with post operative ECMO support, for resuscitative CPB following an acute cardiac arrest incident. The patient could not be weaned from CPB with adequate cardiac output and required systemic ventricular support for 24 hours. Both patients were cannulated from left atrium to ascending aorta. The circuit consisted of 1/4" tubing an electromagnetic flow probe, and a pediatric bio-pump head connected to the Bio-Medicus centrifugal pump. High flows and minimal anticoagulation were maintained and both patients were successfully weaned from the left ventricular assist device. The text will describe the details of perfusion management and patient outcomes. We conclude that ventricular assist is a viable adjunct to the care of infants unable to be weaned from CPB.
21
Jaggy, C., M. Lachat, B. Leskosek, G. Zünd, and M. Turina. "Affinity pump system: a new peristaltic blood pump for cardiopulmonary bypass." Perfusion 15, no. 1 (January 2000): 77–83. http://dx.doi.org/10.1177/026765910001500111.
Анотація:
An in vitro study has been carried out to assess the pump performance of a new peristaltic, extracorporeal displacement pump (Affinity) for cardiopulmonary bypass. The pump system consists of a pump rotor (0-110 rpm), a pump chamber, a venous reservoir with a 5/8″ connecting tube and the Affinity console. The polyurethane chamber is connected to the venous reservoir by a 5/8″ tube and fills passively due to the hydrostatic pressure exhibited by the fluid height in the venous reservoir. The implementation of an occlusive segment in the pump chamber, which collapses in low filling states, should prevent significant negative pressures. An in vitro circuit was filled with bovine blood (37°C, hematocrit 35%) and the pump flow was measured by an ultrasonic transit time flow probe with respect to pre-load, diameter and length of attached tubing in the venous line, pump speed (rpm) and size of the connecting tube (3/8″ and 5/8″). At 108 rpm and a preload equal to 10 mmHg, the flow was 8.6 ± 0.42 l/min for an afterload of 80 mmHg. The reduction of the inlet connector to 3/8″ diminished the pump flow significantly to 5.2 ± 0.31 l/min ( p < 0.0001). The pump flow decreased linearly with respect to the length of the attached tube in the venous line and for a 2 m long 5/8″ silicon tube, the rpm-optimized flow was still 6.0 ± 0.28 l/min at a preload of 10 mmHg. In case of low filling state or too high rpm, the occlusive segment collapsed and no cavitation bubbles could be detected. Our in vitro measurements yield a nomogram for rpm-optimized blood flow with respect to the pre-load in the venous reservoir. The delivered 5/8″ connecting tube facilitates optimum filling of the pump chamber for high blood flow, but limits the use of venous reservoirs to Affinity products. The pump yields a high blood flow even when long tubing in the venous line is used. This makes the pump a candidate for a ventricular assist device. In hypovolemia or high rpm, the occlusive segment collapses and no negative pressure is generated at the inflow site of the pump chamber.
22
Li, Shunran, Zhenghong Dai, Linda Li, Nitin P. Padture, and Peijun Guo. "Time-resolved vibrational-pump visible-probe spectroscopy for thermal conductivity measurement of metal-halide perovskites." Review of Scientific Instruments 93, no. 5 (May 1, 2022): 053003. http://dx.doi.org/10.1063/5.0083763.
Анотація:
Understanding thermal transport at the microscale to the nanoscale is crucially important for a wide range of technologies ranging from device thermal management and protection systems to thermal-energy regulation and harvesting. In the past decades, non-contact optical methods, such as time-domain and frequency-domain thermoreflectance, have emerged as extremely powerful and versatile thermal metrological techniques for the measurement of material thermal conductivities. Here, we report the measurement of thermal conductivity of thin films of CH3NH3PbI3 (MAPbI3), a prototypical metal-halide perovskite, by developing a time-resolved optical technique called vibrational-pump visible-probe (VPVP) spectroscopy. The VPVP technique relies on the direct thermal excitation of MAPbI3 by femtosecond mid-infrared optical pump pulses that are wavelength-tuned to a vibrational mode of the material, after which the time dependent optical transmittance across the visible range is probed in the ns to the μs time window using a broadband pulsed laser. Using the VPVP method, we determine the thermal conductivities of MAPbI3 thin films deposited on different substrates. The transducer-free VPVP method reported here is expected to permit spectrally resolving and spatiotemporally imaging of the dynamic lattice temperature variations in organic, polymeric, and hybrid organic–inorganic semiconductors.
23
Bhat, Ashwath, and Chris Dames. "Structured illumination with infrared imaging for measuring thermal conductivity." Journal of Physics: Conference Series 2766, no. 1 (May 1, 2024): 012010. http://dx.doi.org/10.1088/1742-6596/2766/1/012010.
Анотація:
Abstract With developments in advanced manufacturing and materials by design comes the need for high-throughput thermal characterization and inspection. Towards this end, Structured Illumination with Thermal Imaging (SITI) is an all-optical pump-probe thermal characterization technique recently developed by our group. In the first generation [Zheng et al., Appl. Phys. Rev. 9, 021411 (2022)] SITI uses an LED with a digital micromirror device (DMD) to “structurally illuminate” and heat the sample with dynamic patterns, a visible light camera for thermoreflectance based “thermal imaging” [leveraging a Microsanj MTIR120], and the resultant temperature response was fit with a thermal model to characterize the sample’s thermal properties. This represents a novel approach to dynamic and flexible spatial mapping of thermal properties by virtue of being a non-contact technique and having a simpler scanning means (computer control only) than conventional pump-probe laser methods. SITI also can tolerate rough samples with diffuse reflections. This talk presents the second generation of SITI. The pumping is now based on a lower cost off-the-shelf digital projector. The thermometry is now performed using an infrared (IR) camera, which we find is a more flexible and accessible hardware approach compared to the thermoreflectance microscopy used previously. With these updates the setup can deliver higher heating power and a broader range of frequencies, allowing an extended range of samples that can be studied. We have demonstrated SITI’s ability to measure the thermal conductivity of a microscope glass slide.
24
Borodaenko, Yulia, Stanislav Gurbatov, Evgeny Modin, Aleksandr Chepak, Mikhail Tutov, Aleksandr Mironenko, and Aleksandr Kuchmizhak. "A Laser-Printed Surface-Enhanced Photoluminescence Sensor for the Sub-Nanomolar Optical Detection of Mercury in Water." Chemosensors 11, no. 5 (May 20, 2023): 307. http://dx.doi.org/10.3390/chemosensors11050307.
Анотація:
Here, we report a novel, easy-to-implement scalable single-step procedure for the fabrication of a solid-state surface-enhanced photoluminescence (SEPL) sensor via the direct femtosecond (fs) laser patterning of monocrystalline Si wafers placed under the layer of functionalizing solution simultaneously containing a metal salt precursor (AgNO3) and a photoluminescent probe (d114). Such laser processing creates periodically modulated micro- and nanostructures decorated with Ag nanoparticles on the Si surface, which effectively adsorbs and retains the photoluminescent sensor layer. The SEPL effect stimulated by the micro- and nanostructures formed on the Si surface localizing pump radiation within the near-surface layer and surface plasmons supported by the decorating Ag nanoparticles is responsible for the intense optical sensory response modulated by a small amount of analyte species. The produced SEPL sensor operating within a fluidic device was found to detect sub-nanomolar concentrations of Hg2+ in water which is two orders of magnitude lower compared to this molecular probe sensitivity in solution. The fabrication technique is upscalable, inexpensive, and flexible regarding the ability to the control surface nano-morphology, the amount and type of loading noble-metal nanoparticles, as well as the type of molecular probe. This opens up pathways for the on-demand development of various multi-functional chemosensing platforms with expanded functionality.
25
Lachat, M., C. Jaggy, B. Leskosek, R. Jenni, M. Büchi, G. Zünd, A. Künzli, P. Vogt, and M. Turina. "Optimized performance of the Abiomed BVS 5000: adjustment of the pump height based on Doppler control of the flow pattern." Perfusion 14, no. 1 (January 1999): 59–67. http://dx.doi.org/10.1177/026765919901400109.
Анотація:
The Abiomed BVS 5000 is an automatic volume-driven paracorporeal pulsatile assist device providing left, right or biventricular support. The paracorporeal position allows optical adjustment of filling volumes of the device, which determines the output of the system. A procedure to adjust for maximal stable flow has not yet been established. In vitro measurements have been performed to assess the flow and pressure characteristics of the Abiomed BVS 5000 by raising the preload in 5 mmHg steps before running the system. Doppler probes were placed at the inflow and outflow lines of the pump. After setting the afterload at 80 mmHg the assist device was started. Two measurements were performed to find optimal flow (based on Doppler control and optical adjustment). (1) By Doppler control a stable flow pattern was found at a preload of 25 mmHg with a mean atrial pressure of 5 mmHg and a mean flow of 5.3 ± 0.7 l/min (mean ± standard deviation) at the inflow and outflow sites (the console flow was 4.8 ± 0.4 l/min with a frequency of 61.8 ± 2.0 l/min). (2) Optical adjustment of the pump height gave rise to a preload of 35 mmHg where we recorded a maximal atrial pressure of 107 ± 5.8 mmHg, a maximal retrograde flow of -4.3 ± 1.2 l/min at the inflow and -1.2 ± 0.4 l/min at the outflow site. The mean flow at the inflow and outflow sites was 5.1 ± 0.5 l/min (the console flow was 4.6 ± 0.3 l/min with a frequency of 59.6 ± 2.6 Hz). At an initial afterload of 60 and 40 mmHg the system showed the same qualitative behaviour, but the results were less accurate. Optical adjustment of the pump height may result in an atrioventricular valve insufficiency with undetected retrograde flow and high atrial pressures. We conclude that a Doppler flow probe must be placed at the inflow site to guarantee maximal stable flow.
26
Céolin, Denis, Ji-Cai Liu, Vinícius Vaz da Cruz, Hans Ågren, Loïc Journel, Renaud Guillemin, Tatiana Marchenko, et al. "Recoil-induced ultrafast molecular rotation probed by dynamical rotational Doppler effect." Proceedings of the National Academy of Sciences 116, no. 11 (February 7, 2019): 4877–82. http://dx.doi.org/10.1073/pnas.1807812116.
Анотація:
Observing and controlling molecular motion and in particular rotation are fundamental topics in physics and chemistry. To initiate ultrafast rotation, one needs a way to transfer a large angular momentum to the molecule. As a showcase, this was performed by hard X-ray C1s ionization of carbon monoxide accompanied by spinning up the molecule via the recoil “kick” of the emitted fast photoelectron. To visualize this molecular motion, we use the dynamical rotational Doppler effect and an X-ray “pump-probe” device offered by nature itself: the recoil-induced ultrafast rotation is probed by subsequent Auger electron emission. The time information in our experiment originates from the natural delay between the C1s photoionization initiating the rotation and the ejection of the Auger electron. From a more general point of view, time-resolved measurements can be performed in two ways: either to vary the “delay” time as in conventional time-resolved pump-probe spectroscopy and use the dynamics given by the system, or to keep constant delay time and manipulate the dynamics. Since in our experiment we cannot change the delay time given by the core-hole lifetime τ, we use the second option and control the rotational speed by changing the kinetic energy of the photoelectron. The recoil-induced rotational dynamics controlled in such a way is observed as a photon energy-dependent asymmetry of the Auger line shape, in full agreement with theory. This asymmetry is explained by a significant change of the molecular orientation during the core-hole lifetime, which is comparable with the rotational period.
27
Ikamas, Kęstutis, Ignas Nevinskas, Arūnas Krotkus, and Alvydas Lisauskas. "Silicon Field Effect Transistor as the Nonlinear Detector for Terahertz Autocorellators." Sensors 18, no. 11 (November 2, 2018): 3735. http://dx.doi.org/10.3390/s18113735.
Анотація:
We demonstrate that the rectifying field effect transistor, biased to the subthreshold regime, in a large signal regime exhibits a super-linear response to the incident terahertz (THz) power. This phenomenon can be exploited in a variety of experiments which exploit a nonlinear response, such as nonlinear autocorrelation measurements, for direct assessment of intrinsic response time using a pump-probe configuration or for indirect calibration of the oscillating voltage amplitude, which is delivered to the device. For these purposes, we employ a broadband bow-tie antenna coupled Si CMOS field-effect-transistor-based THz detector (TeraFET) in a nonlinear autocorrelation experiment performed with picoseconds-scale pulsed THz radiation. We have found that, in a wide range of gate bias (above the threshold voltage V th = 445 mV), the detected signal follows linearly to the emitted THz power. For gate bias below the threshold voltage (at 350 mV and below), the detected signal increases in a super-linear manner. A combination of these response regimes allows for performing nonlinear autocorrelation measurements with a single device and avoiding cryogenic cooling.
28
Spence, John C. H. "Approaches to time-resolved diffraction using an XFEL." Faraday Discuss. 171 (2014): 429–38. http://dx.doi.org/10.1039/c4fd00025k.
Анотація:
We describe several schemes for time-resolved imaging of molecular motion using a free-electron laser (XFEL), in response to the many challenges and opportunities which XFEL radiation has created for accurate time-resolved measurement of structure. For pump–probe experiments using crystals, the problem of recording full Bragg reflections (not partials) in each shot arises. Two solutions, the use of the large bandwith which necesarily results from using attosecond pulses, and the use the coherent convergent beam mode are suggested. We also show that with attosecond recording times shorter than the temporal coherence time, Bragg reflections excited by different wavelengths from different reflections can interfere, providing structure factor phase information. For slower processes, a mixing jet sample-delivery device is described to allow snapshot solution scattering during molecular reactions on the microsecond scale. For optically excited membrane proteins, we suggest the use of the lipid cubic phase sample delivery device operating at atmospheric pressure. The use of two-color and split-and-delay schemes is suggested for improved accuracy in the Monte-Carlo method of serial femtosecond crystallography (SFX).
29
Schirò, Giorgio, Joyce Woodhouse, Martin Weik, Ilme Schlichting, and Robert L. Shoeman. "Simple and efficient system for photoconverting light-sensitive proteins in serial crystallography experiments." Journal of Applied Crystallography 50, no. 3 (June 1, 2017): 932–39. http://dx.doi.org/10.1107/s1600576717006264.
Анотація:
Proteins that change their structure in response to light absorption regulate many functional processes in living cells. Moreover, biotechnological approaches like optogenetics and super-resolution fluorescence microscopy recently triggered the generation of new genetically modified photosensitive proteins. Light-induced structural changes in photosensitive proteins can be studied by time-resolved serial femtosecond crystallography (SFX), an X-ray diffraction technique that allows the determination of macromolecular structures at X-ray free-electron lasers from a large number of nano- to micro-sized crystals. This article describes a simple and efficient system for converting photosensitive proteins into light-induced semi-stationary states by inline laser illumination prior to sample injection with a gas-focused liquid jet and subsequent optical pump–X-ray probe exposure. The simple setup of this device makes it suitable for integration into other liquid injectors (like electro-spinning and electro-kinetic injectors) and potentially also in high-viscosity extruders, provided that embedding microcrystals in viscous media does not alter protein photophysical properties. The functioning of the device is demonstrated with an example of a photoswitchable fluorescent protein pre-illuminated (photoactivated) for time-resolved SFX experiments. The device can be easily adapted for the conversion in time-resolved SFX experiments of other microcrystalline proteins, such as photosystems, phytochromes and rhodopsins.
30
Irfan, Irfan Syaputra Sianturi, and Junedi Ginting. "Temperature Monitoring System and pH Control of Catfish Breeding Pond Water Based on NodeMCU 8266 with Telegram Bot Notification." Journal of Technomaterial Physics 4, no. 2 (August 31, 2022): 122–28. http://dx.doi.org/10.32734/jotp.v4i2.8325.
Анотація:
This research presents the design of a temperature monitoring and pH control device for catfish nurseries. The pH range of 6.5 to 8.5 with a temperature of 27℃ to 31℃ is the optimal condition for catfish farming. However, water quality can decrease due to unstable pH conditions and temperature changes. In this case, periodic monitoring is necessary to maintain stable pH and temperature conditions. This tool is constructed to monitor temperature and control water pH using DS18B20 temperature sensors, pH sensors, water pumps, Node MCU 8266, and a telegram application. This device is applied to maintain the stability of the pH of the water; pH control is carried out with a new water replacement method when the pH value is over the normal limit or is in acid and alkaline state. The new water replacement method is carried out by utilizing a water pump for the circulation process. When all components are well integrated into a system, including the whole program, then testing is carried out. Testing on this tool begins with turning on and running the system and observing the system's performance, dipping the temperature sensor and pH sensor probe into the water, and then observing the temperature and pH data displayed on the LCD. Furthermore, if the pH is in an acid or alkaline state, the pump will be active to carry out the process of circulating water replacement. The output of water temperature and pH measurements is displayed on the LCD and with Telegram notifications by sending messages or statuses on Telegram.
31
Wong, Victor, and Giovanni Fanchini. "(Invited) Near-Field Optics and Its Applications in Nanophotonic Devices: A Review." ECS Meeting Abstracts MA2023-02, no. 34 (December 22, 2023): 1630. http://dx.doi.org/10.1149/ma2023-02341630mtgabs.
Анотація:
In our presentation, we will offer an overview of aperture-type scanning near field optical microscopy (SNOM) – a family of nano-optical imaging techniques derived from scanning probe microscopy which are capable of subwavelength resolution, and the development of three dimensional (3D) SNOM methods undertaken by our group to locally image the distribution of the electromagnetic radiation in the proximity of nanoparticles and nano-objects.[1] We will discuss a few applications in which we took advantage of 3D-SNOM to design specific optical nanosystems for light harvesting device applications. Specific case studies that will be presented include the design of plasmonic thin-film solar cells enhanced by random arrays of copper nanoparticles,[2] and the use of 3D-SNOM for characterizing evanescent waveguides self-assembled from of copper nanoparticles assembled on thin films of graphene.[3] In the final part of our talk, we will we present near-field scanning thermoreflectance imaging (NeSTRI), a new pump-probe technique invented in our group (see Figure 1) in which an aperture-type SNOM is used to contactlessly determine the thermal conductivity of inhomogeneous thin films and low-dimensional systems at the nanoscale for heat-spreading and thermoelectric applications.[4,5] These examples well represent the versatility of SNOM imaging and its potential for designing an even wider family of nano-optical devices. [1] P Bazylewski, S Ezugwu, G Fanchini, Applied Sciences 7 (2017) 973 [2] S Ezugwu, H Ye, G Fanchini, Nanoscale 7 (2016) 252-260 [3] T Ouyang, A Akbari-Sharbaf, J Park, R Bauld, MG Cottam, G Fanchini, RSC Advances 5 (2015) 98814-98821 [4] S Ezugwu, S Kazemian, DYW Choi, G Fanchini, Nanoscale 9 (2017) 4097-4106 [5] S Kazemian, S Ezugwu, G Fanchini, Proc. SPIE 10926, Quantum Sensing and Nano Electronics and Photonics XVI, 109260L (1 February 2019); doi: 10.1117/12.2509828 Figure 1
32
Glazunov, I. V., N. A. Skoptsov, A. M. Malyarevich, K. V. Yumashev та P. A. Loiko. "DEVICE FOR MEASURMENT OF RELAXATION TIME OF THE BLEACHED STATE OF OPTICAL MATERIALS BY THE «PUMP-PROBE» METHOD IN SUB-ΜS TIME DOMAIN". Devices and Methods of Measurements 7, № 1 (6 червня 2016): 24–31. http://dx.doi.org/10.21122/2220-9506-2016-7-1-24-31.
33
Lee, Ah Young, and Joo Young Cho. "Advancements in hemostatic strategies for managing upper gastrointestinal bleeding: A comprehensive review." World Journal of Gastroenterology 30, no. 15 (April 21, 2024): 2087–90. http://dx.doi.org/10.3748/wjg.v30.i15.2087.
Анотація:
Upper gastrointestinal (GI) hemorrhage presents a substantial clinical challenge. Initial management typically involves resuscitation and endoscopy within 24 h, although the benefit of very early endoscopy (< 12 h) for high-risk patients is debated. Treatment goals include stopping acute bleeding, preventing rebleeding, and using a multimodal approach encompassing endoscopic, pharmacological, angiographic, and surgical methods. Pharmacological agents such as vasopressin, prostaglandins, and proton pump inhibitors are effective, but the increase in antithrombotic use has increased GI bleeding morbidity. Endoscopic hemostasis, particularly for nonvariceal bleeding, employs techniques such as electrocoagulation and heater probes, with concerns over tissue injury from monopolar electrocoagulation. Novel methods such as Hemospray and Endoclot show promise in creating mechanical tamponades but have limitations. Currently, the first-line therapy includes thermal probes and hemoclips, with over-the-scope clips emerging for larger ulcer bleeding. The gold probe, combining bipolar electrocoagulation and injection, offers targeted coagulation but has faced device-related issues. Future advancements involve combining techniques and improving endoscopic imaging, with studies exploring combined approaches showing promise. Ongoing research is crucial for developing standardized and effective hemorrhage management strategies.
34
Kaliszewski, Miron, Maksymilian Włodarski, Jarosław Młyńczak, Bartłomiej Jankiewicz, Lukas Auer, Bartosz Bartosewicz, Malwina Liszewska, et al. "The Multi-Gas Sensor for Remote UAV and UGV Missions—Development and Tests." Sensors 21, no. 22 (November 16, 2021): 7608. http://dx.doi.org/10.3390/s21227608.
Анотація:
In this article, we present a versatile gas detector that can operate on an unmanned aerial vehicle (UAV) or unmanned ground vehicle (UGV). The device has six electrochemical modules, which can be selected to measure specific gases, according to the mission requirements. The gas intake is realized by a miniaturized vacuum pump, which provides immediate gas distribution to the sensors and improves a fast response. The measurement data are sent wirelessly to the operator’s computer, which continuously stores results and presents them in real time. The 2 m tubing allows measurements to be taken in places that are not directly accessible to the UGV or the UAV. While UAVs significantly enhanced the versatility of sensing applications, point gas detection is challenging due to the downwash effect and gas dilution produced by the rotors. In our work, we demonstrated the method of downwash effect reduction at aerial point gas measurements by applying a long-distance probe, which was kept between the UAV and the examined object. Moreover, we developed a safety connection protecting the UAV and sensor in case of accidental jamming of the tubing inside the examined cavity. The methods presented provide an effective gas metering strategy using UAVs.
35
Mykytenko, James, Thomas A. Vassiliades, and Jacob Vinten-Johansen. "Displacement of the Beating Heart with a Low-Profile Suction-Based Apical Positioning Device in a Closed Chest." Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery 2, no. 1 (January 2007): 14–19. http://dx.doi.org/10.1097/01.imi.0000244106.79590.bd.
Анотація:
Background Off-pump, multivessel, endoscopic coronary artery bypass requires cardiac displacement within an intact chest. The current study evaluated right ventricular performance and systemic hemodynamics while exposing the posterior surface of the heart using a novel, low-profile, apical suction-based cardiac positioner in a closed-chest, beating-heart model. Methods Six pigs underwent instrumentation with continuous monitoring of arterial pressure by fluid-filled transducer and cardiac output and coronary blood flow by ultrasound transit time flow probe. Right ventricular (RV) pressure-volume loops were generated by an impedance catheter. Heart rate was maintained between 80 and 100 beats per minute pharmacologically. The cardiac positioner displaced the heart endoscopically through a port. Data were obtained in 5 sequential phases: (1) baseline/free-beating, (2) positioner coaptation, (3) addition of Trendelenburg, (4) cardiac displacement with Trendelenburg, and (5) cardiac displacement without Trendelenburg. Results Cardiac displacement without Trendelenburg (Phase 5) resulted in a significant (P < 0.05) decrease in cardiac output, coronary blood flow, RV systolic pressure (RVSP), mean arterial pressure, RV end-diastolic volume (RVEDV), and RV end-systolic volume (RVESV) compared with baseline (Phase 1). With Trendelenburg added to cardiac displacement (Phase 4), all parameters improved, but only RVSP, mean arterial pressure, and RVEDV were comparable to baseline (Phase 1). There were no local complications from device coaptation. Conclusions The low-profile endoscopic cardiac positioner is safe and effective in the closed-chest, beating-heart porcine model. Nevertheless, cardiac displacement in a closed chest does cause impairment in ventricular performance that can be ameliorated by the addition of Trendelenburg and further technological progress.
36
Wang, Yong, Jorge Fonseca-Campos, Wan-guo Liang, Chang-Qing Xu, and Ignacio Vargas-Baca. "Noise Analysis of Second-Harmonic Generation in Undoped and MgO-Doped Periodically Poled Lithium Niobate." Advances in OptoElectronics 2008 (October 30, 2008): 1–10. http://dx.doi.org/10.1155/2008/428971.
Анотація:
Noise characteristics of second-harmonic generation (SHG) in periodically poled lithium niobate (PPLN) using the quasiphase matching (QPM) technique are analyzed experimentally. In the experiment, a0.78 μm second-harmonic (SH) wave was generated when a 1.56 μm fundamental wave passed through a PPLN crystal (bulk or waveguide). The time-domain and frequency-domain noise characteristics of the fundamental and SH waves were analyzed. By using the pump-probe method, the noise characteristics of SHG were further analyzed when a visible light (532 nm) and an infrared light (1090 nm) copropagated with the fundamental light, respectively. The noise characterizations were also investigated at different temperatures. It is found that for the bulk and waveguide PPLN crystals, the SH wave has a higher relative noise level than the corresponding fundamental wave. For the same fundamental wave, the SH wave has lower noise in a bulk crystal than in a waveguide, and in MgO-doped PPLN than in undoped PPLN. The 532 nm irradiation can lead to higher noise in PPLN than the 1090 nm irradiation. In addition, increasing temperature of device can alleviate the problem of noise in conjunction with the photorefractive effect incurred by the irradiation light. This is more significant in undoped PPLN than in MgO-doped one.
37
Yang, Jie, Markus Guehr, Theodore Vecchione, Matthew S. Robinson, Renkai Li, Nick Hartmann, Xiaozhe Shen, et al. "Femtosecond gas phase electron diffraction with MeV electrons." Faraday Discussions 194 (2016): 563–81. http://dx.doi.org/10.1039/c6fd00071a.
Анотація:
We present results on ultrafast gas electron diffraction (UGED) experiments with femtosecond resolution using the MeV electron gun at SLAC National Accelerator Laboratory. UGED is a promising method to investigate molecular dynamics in the gas phase because electron pulses can probe the structure with a high spatial resolution. Until recently, however, it was not possible for UGED to reach the relevant timescale for the motion of the nuclei during a molecular reaction. Using MeV electron pulses has allowed us to overcome the main challenges in reaching femtosecond resolution, namely delivering short electron pulses on a gas target, overcoming the effect of velocity mismatch between pump laser pulses and the probe electron pulses, and maintaining a low timing jitter. At electron kinetic energies above 3 MeV, the velocity mismatch between laser and electron pulses becomes negligible. The relativistic electrons are also less susceptible to temporal broadening due to the Coulomb force. One of the challenges of diffraction with relativistic electrons is that the small de Broglie wavelength results in very small diffraction angles. In this paper we describe the new setup and its characterization, including capturing static diffraction patterns of molecules in the gas phase, finding time-zero with sub-picosecond accuracy and first time-resolved diffraction experiments. The new device can achieve a temporal resolution of 100 fs root-mean-square, and sub-angstrom spatial resolution. The collimation of the beam is sufficient to measure the diffraction pattern, and the transverse coherence is on the order of 2 nm. Currently, the temporal resolution is limited both by the pulse duration of the electron pulse on target and by the timing jitter, while the spatial resolution is limited by the average electron beam current and the signal-to-noise ratio of the detection system. We also discuss plans for improving both the temporal resolution and the spatial resolution.
38
Rosner, M., D. Beck, P. Fierlinger, H. Filter, C. Klau, F. Kuchler, P. Rößner, M. Sturm, D. Wurm, and Z. Sun. "A highly drift-stable atomic magnetometer for fundamental physics experiments." Applied Physics Letters 120, no. 16 (April 18, 2022): 161102. http://dx.doi.org/10.1063/5.0083854.
Анотація:
We report the design and performance of a nonmagnetic drift stable optically pumped cesium magnetometer with a measured sensitivity of 35 fT at 200 s integration time and stability below 50 fT between 70 and 600 s. The sensor is based on the nonlinear magneto-optical rotation effect: in a Bell–Bloom configuration, a higher order polarization moment (alignment) of Cs atoms is created with a pump laser beam in an anti-relaxation coated Pyrex cell under vacuum, filled with Cs vapor at room temperature. The polarization plane of light passing through the cell is modulated due the precession of the atoms in an external magnetic field of 2.1 μT, used to optically determine the Larmor precession frequency. Operation is based on a sequence of optical pumping and observation of freely precessing spins at a repetition rate of 8 Hz. This free precession decay readout scheme separates optical pumping and probing and, thus, ensures a systematically highly clean measurement. Due to the residual offset of the sensor of <15 pT together with negligible crosstalk of adjacent sensors, this device is uniquely suitable for a variety of experiments in low-energy particle physics with extreme precision, here as a highly stable and systematically clean reference probe in search for time-reversal symmetry violating electric dipole moments.
39
GÓMEZ-DÍAZ, J. J., A. SANTIESTEBAN-LÓPEZ, E. PALOU, and A. LÓPEZ-MALO. "Zygosaccharomyces bailii Inactivation by Means of UV Light and Low-Frequency Ultrasound Treatments." Journal of Food Protection 74, no. 10 (October 1, 2011): 1751–55. http://dx.doi.org/10.4315/0362-028x.jfp-10-522.
Анотація:
Zygosaccharomyces bailii inactivation suspended in apple juice was evaluated under the effects of selected treatments: short-wave UV light (UVC, using one or two lamps), or low-frequency ultrasound (US), or their simultaneous combination. US treatments (20 kHz, 120-μm wave amplitude) were performed at 35°C in a double-wall vessel by using a 13-mm probe. The UVC device consists of two 90-cm-long stainless steel tubes with 40-W UVC lamps covered with quartz tubes, each one inside a stainless steel tube (annular inside diameter of 2.6 cm) connected to a peristaltic pump. Inoculated systems were recirculated through individual or simultaneous US and UVC treatments, samples were taken periodically, and yeast survivors were determined by the plate-count technique. Yeast survival curves demonstrated that UVC alone or in combination with US produced higher inactivation than US alone. Survival curves were appropriately described by the Weibull distribution of resistances model, obtaining model parameter values that adequately reflected the effect of the studied treatments. For every tested case, the distribution of resistances model revealed an absence of mode, while mean values and variances decreased when simultaneous UVC irradiation with two lamps and US were applied, reaching a 7-log cycle reduction after 40 min of treatment. Combined treatment was more effective than individual US or UVC treatments.
40
Doak, R. Bruce, Gabriela Nass Kovacs, Alexander Gorel, Lutz Foucar, Thomas R. M. Barends, Marie Luise Grünbein, Mario Hilpert, et al. "Crystallography on a chip – without the chip: sheet-on-sheet sandwich." Acta Crystallographica Section D Structural Biology 74, no. 10 (October 1, 2018): 1000–1007. http://dx.doi.org/10.1107/s2059798318011634.
Анотація:
Crystallography chips are fixed-target supports consisting of a film (for example Kapton) or wafer (for example silicon) that is processed using semiconductor-microfabrication techniques to yield an array of wells or through-holes in which single microcrystals can be lodged for raster-scan probing. Although relatively expensive to fabricate, chips offer an efficient means of high-throughput sample presentation for serial diffraction data collection at synchrotron or X-ray free-electron laser (XFEL) sources. Truly efficient loading of a chip (one microcrystal per well and no wastage during loading) is nonetheless challenging. The wells or holes must match the microcrystal size of interest, requiring that a large stock of chips be maintained. Raster scanning requires special mechanical drives to step the chip rapidly and with micrometre precision from well to well. Here, a `chip-less' adaptation is described that essentially eliminates the challenges of loading and precision scanning, albeit with increased, yet still relatively frugal, sample usage. The device consists simply of two sheets of Mylar with the crystal solution sandwiched between them. This sheet-on-sheet (SOS) sandwich structure has been employed for serial femtosecond crystallography data collection with micrometre-sized crystals at an XFEL. The approach is also well suited to time-resolved pump–probe experiments, in particular for long time delays. The SOS sandwich enables measurements under XFEL beam conditions that would damage conventional chips, as documented here. The SOS sheets hermetically seal the sample, avoiding desiccation of the sample provided that the X-ray beam does not puncture the sheets. This is the case with a synchrotron beam but not with an XFEL beam. In the latter case, desiccation, setting radially outwards from each punched hole, sets lower limits on the speed and line spacing of the raster scan. It is shown that these constraints are easily accommodated.
41
Johagen, Daniel, Micael Appelblad, and Staffan Svenmarker. "Can the Oxygenator Screen Filter Reduce Gaseous Microemboli?" Journal of ExtraCorporeal Technology 46, no. 1 (March 2014): 60–66. http://dx.doi.org/10.1051/ject/201446060.
Анотація:
Gaseous microemboli (GME) define small bubbles as <200 μm in size. GME are reported to increase morbidity after cardiopulmonary bypass (CPB) and cardiac surgery. To prevent intrusion of GME into the systemic circulation during CPB, arterial line filtration is generally recommended. New trends in oxygenator design promote location of arterial filtration as an integral part of the oxygenator housing. The present experimental study aimed to evaluate the GME removal properties of an integrated arterial screen filter in a standard microporous oxygenator. The GME properties of Terumo Capiox® FX25 with an integrated arterial screen filter was assessed in an experimental setup and compared with Capiox® RX25, in which no arterial screen filter is present. A blood analog prime solution was recirculated using a roller pump at 4 and 6 L per minute flow rate, respectively, through a customized CPB circuit comprising oxygenator, reservoir, and connecting tubing. A controlled volume of air was introduced into the circuit. The GME activity was measured and computed using a Gampt BCC200® ultrasonic device placing one probe at the venous inlet and one other at the arterial outlet of the oxygenator. Transmembrane delta values of GME activity were used to calculate the removal efficacy based on counts and volume of GME. Use of screen filtration reduced the GME volume by 99.1% ± .1% compared with 98.0% ± .1% for controls at 4 L/min flow rate (p < .001). At 6 L/min, the reduction was 97.9% ± .1% compared with 97.0% ± .1% (p < .001). In contrast, the reduction of GME counts was less effective after screen filtration compared with controls: 89.6 ± .6% versus 91.4 ± .4% at 4 L/min and 55.6% ± 1.6% versus 76.0% ± 1.4% at 6 L/min, respectively (p < .001). The tested oxygenator with incorporated arterial screen filter reduced GME activity based on the calculated volume at the same time as counts of GME increased.
42
Kholodenko, Arnold, and Michael Rivkin. "Mechanical Seal with Elastomeric Rotating Element. Part 1: Theory of Operation." Rubber Chemistry and Technology 67, no. 1 (March 1, 1994): 42–61. http://dx.doi.org/10.5254/1.3538666.
Анотація:
Abstract This paper presents the results of fundamental research on flexible faced mechanical shaft seals. The effect of stretch and preload on the contact stress were investigated using a nonlinear finite element modeling package. The characteristics of the rubber materials including the stress-strain curves to elongation at break were required to complete the analysis. Pressure forces resulting from the static pressure in the pump stuffing box as well as the friction effects on all contacting surfaces were considered in the model. Stress distribution across the contact surface established the basis for the formation of multiple distinct lips: at least one on the outside or fluid side of the seal and the other on the inside or air side of the seal. This phenomenon is explained by the step change in magnitude of axial stress while traversing the contact in the radial direction allowing the formation of exterior lips and the development of an annular region trapping debris products and process fluid. Photomicrographic images of the wear track taken with a Scanning Probe Microscope show distinct wear tracks and the topology of each. Although the chemical composition of the debris in the annular spaces has not been determined quantitatively, increased levels of fluorine were present, suggesting fragments of the monomers in the elastomeric rotary or migration of Teflon fillers. Axial variations in the stretched rotary dimensions (waviness) affects seal performance. Statistics for a typical batch of rotary elements are presented and a method of factoring these variations into the seal design is presented. The formation of axial waves on the contact vertex affects the seal performance and is considered in the final design of the seal pair configuration. The results of this work were incorporated into a suite of mechanical face seals covering shaft sizes from 1.125 to 5.000 inches using seven pairs of seals, each pair consisting of a stretched rotary sliding against an unlapped silicon carbide annular ring. Each of these seal pairs were tested on an experimental test device to determine the heat generation and friction coefficients for a wide range of temperature, pressure, speed, and sealing fluid. Results of the experimental work are reported in a companion paper.
43
Opsal, Jon, and Allan Rosencwaig. "Physics of Thermal Wave NDE of Semiconductor Materials and Devices." MRS Bulletin 13, no. 4 (April 1988): 28–33. http://dx.doi.org/10.1557/s0883769400065866.
Анотація:
Thermal wave physics is playing an ever increasing role in the on-line characterization of semiconductor materials and devices. This is especially true for thermal wave methods that employ laser beams for both the generation and detection of thermal waves. For the modulated reflectance method discussed here, the pump and probe beams are focused on the same spot. They therefore achieve the noncontact advantage of optical methods in addition to the optimum condition for high spatial resolution, a necessary condition for thermal wave measurements on product wafers.When a material is excited with an intensity-modulated laser beam or pump, a thermal wave is generated in the material and in the air above the sample. The material within this heated region will undergo a thermal expansion which can be detected with a probe beam interferometer or by deflecting the probe beam from the thermoelastic deformation of the surface. Since the complex refractive index of most materials depends on temperature, a modulated temperature will also induce a corresponding modulation in the refractive index and consequently a modulation on a probe beam passing anywhere near the thermal wave. A probe beam directed along the heated surface of the sample, for example, will be deflected as it passes through the heated region above the surface. This mirage effect can also be observed within the sample by directing a transmitting probe through the heated region beneath the surface. Likewise, using a probe beam directed onto the sample surface one can observe a modulation in reflection, transmission, or scattering. A related noncontact method is the photothermal measurement of infrared radiation emitted from the material's heated region. Note that with all these detection methods, thermal wave measurements can be, and most often are, done in air and at room temperature.
44
Sun, C. K., B. Golubovic, H. K. Choi, C. A. Wang, and J. G. Fujimoto. "Heterodyne nondegenerate pump–probe measurement technique for guided-wave devices." Optics Letters 20, no. 2 (January 15, 1995): 210. http://dx.doi.org/10.1364/ol.20.000210.
45
Liu, Hongyuan, Xunjun He, Jie Ren, Jiuxing Jiang, Yongtao Yao, and Guangjun Lu. "Terahertz Modulation and Ultrafast Characteristic of Two-Dimensional Lead Halide Perovskites." Nanomaterials 12, no. 20 (October 11, 2022): 3559. http://dx.doi.org/10.3390/nano12203559.
Анотація:
In recent years, two-dimensional (2D) halide perovskites have been widely used in solar cells and photoelectric devices due to their excellent photoelectric properties and high environmental stability. However, the terahertz (THz) and ultrafast responses of the 2D halide perovskites are seldom studied, limiting the developments and applications of tunable terahertz devices based on 2D perovskites. Here, 2D R-P type (PEA)2(MA)2Pb3I10 perovskite films are fabricated on quartz substrates by a one-step spin-coating process to study their THz and ultrafast characteristics. Based on our homemade ultrafast optical pump–THz probe (OPTP) system, the 2D perovskite film shows an intensity modulation depth of about 10% and an ultrafast relaxation time of about 3 ps at a pump power of 100 mW due to the quantum confinement effect. To further analyze the recombination mechanisms of the photogenerated carriers, a three-exponential function is used to fit the carrier decay processes, obtaining three different decay channels, originating from free carrier recombination, exciton recombination, and trap-assisted recombination, respectively. In addition, the photoconductor changes (∆σ) at different pump–probe delay times are also investigated using the Drude-Smith model, and a maximum difference of 600 S/m is obtained at τp = 0 ps for a pump power of 100 mW. Therefore, these results show that the 2D (PEA)2(MA)2Pb3I10 film has potential applications in high-performance tunable and ultrafast THz devices.
46
Chu, Lingqiao, Kai Zhang, Jin Yang, Huachao Jiang, Zhenyou Wang, and Fuhai Su. "Anisotropic electron and lattice dynamics in excitonic insulator Ta2NiSe5." AIP Advances 12, no. 5 (May 1, 2022): 055119. http://dx.doi.org/10.1063/5.0086701.
Анотація:
We employ polarization-resolved femtosecond optical pump–probe spectroscopy to investigate the nonequilibrium photocarrier dynamics in excitonic insulator Ta2NiSe5. The electronic dynamics, including hot carrier cooling, exciton formation, and recombination in the timescale ranging from subpicoseconds to a few tens of picoseconds, have been established from the transient reflectivity spectra, showing strong in-plane anisotropy with respect to the probe polarization. Such anisotropic photocarrier dynamics possibly arise from the crystalline orientation dependence of the excitonic polarizability. Furthermore, we find that the amplitude of coherent phonons with a frequency of 1 THz is subject to the probe polarization, whereas it is not sensitive to the pump polarization. This substantiates that the displacive excitation of coherent phonons plays a decisive role in lattice dynamics. In addition, we find that the photo-induced dielectric screening tends to suppress the amplitude of coherent phonons with increasing pump fluence, manifesting a remarkable polarization dependence. Our work provides valuable insights into the excitonic dynamics and the origin of coherent phonon generation and also may contribute to the development of polarization-sensitive photoelectric devices based on Ta2NiSe5.
47
Mizokawa, Takashi. "Manipulating Electronic Structure by Laser Pump-Photoemission Probe in Oxides." Advances in Science and Technology 67 (October 2010): 198–205. http://dx.doi.org/10.4028/www.scientific.net/ast.67.198.
Анотація:
We report on photoemission studies of SrTiO3, Pr0.55(Ca1-ySry)0.45MnO3 (PCSMO, y=0.25,0.40), and Ti1-xCoxO2-δ (x=0.05, 0.10) under laser illumination and discuss the origins of the unusual electronic structure changes induced by optical excitation at the surfaces of these transition-metal oxides. The present study shows that photoemission spectroscopy is a powerful tool to explore novel photo-induced electronic states which can open up possibilities of new optical devices.
48
Tanasanchai, N., P. Siriworakoonchai, P. Udommai, and W. Anukool. "Exploring the Zeeman effect in spectroscopy for laser frequency manipulation in optical systems." Journal of Physics: Conference Series 2653, no. 1 (December 1, 2023): 012035. http://dx.doi.org/10.1088/1742-6596/2653/1/012035.
Анотація:
Abstract In optical systems, acousto-optic modulators (AOMs) and electro-optic modulators (EOMs) are commonly utilized for laser frequency manipulation. However, these devices come with drawbacks such as high cost and the requirement of optical adjustments to change the frequency shift direction. In this study, we propose an alternative method that harnesses the Zeeman effect in the saturated-absorption spectroscopy to shift the energy levels in atom. With this technique, the laser frequency can be shifted without the need for AOMs or EOMs. The stability of laser locking was investigated for any case of polarization of probe and pump beam. We found when the polarization of the probe and pump beams is linear and perpendicular, it results in the highest level of stability in laser locking compared to other polarization configurations.
49
Wang, Zi-Han, Cheul-Hyun Yoon, Shoji Yoshida, Yusuke Arashida, Osamu Takeuchi, Yuzo Ohno, and Hidemi Shigekawa. "Surface-mediated spin dynamics probed by optical-pump–probe scanning tunneling microscopy." Physical Chemistry Chemical Physics 21, no. 14 (2019): 7256–60. http://dx.doi.org/10.1039/c8cp07786j.
50
Renaud, Thibaut, Heming Huang, Frédéric Grillot, and Dieter Bimberg. "Wave mixing efficiency in InAs/GaAs semiconductor quantum dot optical amplifiers and lasers." Laser Physics Letters 19, no. 11 (October 7, 2022): 116202. http://dx.doi.org/10.1088/1612-202x/ac9595.
Анотація:
Abstract The nonlinear features of both semiconductor optical amplifiers (SOAs) and semiconductor lasers, which are made from the same InAs/GaAs quantum dot (QD) wafers, are investigated in detail. By employing pump-probe driven four-wave mixing as an experimental tool, the wave conversion process shows notably different profiles for the two types of devices. Due to the contributions of ultrafast, sub-picosecond mechanisms, such as carrier heating and spectral hole burning, the pump-probe frequency can be easily tuned to the THz range. SOAs generally benefit more from sub-picosecond carrier dynamics, hence exhibiting a higher conversion efficiency (CE) in the THz range, compared to their laser diode counterparts. The discrepancy even exceeds 10 dB. In addition, laser experiments yield some differences from the amplifier ones, hence leading to a higher nonlinear CE at small detuning ranges. These results strongly improve our insight into the fundamental nonlinear properties of InAs/GaAs QD material, and contribute to the conception of novel devices for future on-chip applications in all-optical communication networks, such as signal wavelength conversion, mode-locking, and optical frequency comb generation.