9R phase enabled superior radiation stability of nanotwinned Cu alloys via in situ radiation at elevated temperature

Nanotwinned metals exhibit outstanding radiation tolerance as twin boundaries effectively engage, transport and eliminate radiation-induced defects. However, radiation-induced detwinning may reduce the radiation tolerance associated with twin boundaries, especially at elevated temperatures. Here we show, via in-situ Kr ion irradiation inside a transmission electron microscope, that 3 at. % Fe in epitaxial nanotwinned Cu (Cu97Fe3) significantly improves the thermal and radiation stability of nanotwins during radiation up to 5 displacements-per-atom at 200 °C. Such enhanced stability of nanotwins is attributed to a diffuse 9R phase resulted from the dissociation of incoherent twin boundaries in nanotwinned Cu97Fe3. The mechanisms for the enhanced stability of twin boundaries in irradiated nanotwinned alloys are discussed. The stabilization of nano-twins opens up opportunity for the application of nanotwinned alloys for aggressive radiation environments. Includes supplemental Appendix. Video files are attached below

Original Article Hyperbaric spinal anesthesia with ropivacaine coadministered with sufentanil for cesarean delivery: a dose-response study

Abstract: Adjuvant sufentanil could achieve effective spinal anesthesia with low dose of hyperbaric ropivacaine for cesarean delivery. Two previous studies had calculated the 50% effective dose (ED50) of intrathecal ropivacaine coadministered with sufentanil for cesarean delivery. However, the 95% effective dose (ED95) of intrathecal hyperbaric ropivacaine coadministered with sufentanil for cesarean delivery remains uncertain. This study determined the ED95 of intrathecal hyperbaric ropivacaine coadministered with sufentanil for cesarean delivery. 80 ASA physical status I or II parturients undergoing elective cesarean delivery were enrolled in this prospective, randomized, double-blind investigation. A combined spinal and epidural anesthesia was performed at the L3-L4 interspace. Patients received a dose of spinal ropivacaine coadministered with sufentanil 5 μg diluted to 3.0 ml with normal saline and 0.5 ml of 10% dextrose: 7.5 mg (n = 20), 9.0 mg (n = 20), 10.5 mg (n = 20), or 12 mg (n = 20). An effective dose was defined as a dose that provided bilateral sensory block to T7 within 10 min after intrathecal drug administration and required no epidural top-up for surgery to be completed. The ED50 and ED95 values for successful anesthesia were determined using a logistic regression model. The ED50 (95% confidence interval [CI]) for successful anesthesia was 8.4 (4.0-9.8) mg and the ED95 (95% CI) was 11.4 (9.7-13.9) mg. The results show that the ED95 of intrathecal hyperbaric ropivacaine coadministered with sufentanil 5 μg for cesarean delivery was 11.4 mg. The addition of sufentanil could significantly reduce the dosage of ropivacaine

Improvement of current crowding effect in VCSEL arrays with non-uniform oxidation aperture design

A compact electro-opto-thermal model of 2-D vertical cavity surface emitting laser (VCSEL) arrays considering the current crowding effect in each array cell is established to study the impact of oxidation aperture on the device performance. Simulated results shows that increasing oxidation aperture of array cell is helpful to improve the uniformity of current density distribution. With careful design of non-uniform oxidation aperture layout, both the uniformity of the temperature distribution and the current distribution is improved by 36.52% and 42.08%, respectively. Furthermore, 3×3 VCSEL arrays with uniform oxidation aperture (array-1) and non-uniform oxidation aperture (array-2) are fabricated and the L-I-V curves of two types of VCSEL arrays at different biases are also measured. The peak output optical power of array-2 is enhanced to 1.83mW with an improvement of 8.91% when compared with that of array-1. Moreover, the total optical output power of array-2 is always superior to that of array-1 over a wide bias current range

Improvement of thermally induced current bifurcation in VCSEL arrays with non-uniform series resistance design

Non-uniform series resistance design of VCSEL arrays is studied to improve thermally induced current bifurcation based on an electro-opto-thermal model of VCSEL arrays. Taking an 850nm VCSEL array with 4×4 cells for example, the impact of series resistance on current bifurcation is investigated. Increasmg series resistance is helpful to enhance the critical current values of current bifurcation point (Irc) and hence delay the current bifurcation phenomenon. For VCSEL array with non-uniform series resistance, Irc is increased by 28.6% and the total output optical power is enhanced by 14.3% when compared with that of VCSEL array with uniform series resistance. Therefore, non-uniform series resistance design is a better method for delaying the current bifurcation phenomenon and enhancuig the output optical power of VCSEL arrays

A Comparative Study of Systolic and Diastolic Mechanical Synchrony in Canine, Primate, and Healthy and Failing Human Hearts.

Aim: Mechanical dyssynchrony (MD) is associated with heart failure (HF) and may be prognostically important in cardiac resynchronization therapy (CRT). Yet, little is known about its patterns in healthy or diseased hearts. We here investigate and compare systolic and diastolic MD in both right (RV) and left ventricles (LV) of canine, primate and healthy and failing human hearts. Methods and Results: RV and LV mechanical function were examined by pulse-wave Doppler in 15 beagle dogs, 59 rhesus monkeys, 100 healthy human subjects and 39 heart failure (HF) patients. This measured RV and LV pre-ejection periods (RVPEP and LVPEP) and diastolic opening times (Q-TVE and Q-MVE). The occurrence of right (RVMDs) and left ventricular systolic mechanical delay (LVMDs) was assessed by comparing RVPEP and LVPEP values. That of right (RVMDd) and left ventricular diastolic mechanical delay (LVMDd) was assessed from the corresponding diastolic opening times (Q-TVE and Q-MVE). These situations were quantified by values of interventricular systolic (IVMDs) and diastolic mechanical delays (IVMDd), represented as positive if the relevant RV mechanical events preceded those in the LV. Healthy hearts in all species examined showed greater LV than RV delay times and therefore positive IVMDs and IVMDd. In contrast a greater proportion of the HF patients showed both markedly increased IVMDs and negative IVMDd, with diastolic mechanical asynchrony negatively correlated with LVEF. Conclusion: The present IVMDs and IVMDd findings have potential clinical implications particularly for personalized setting of parameter values in CRT in individual patients to achieve effective treatment of HF

Modelling and Performance Analysis of Cyclic Hydro-Pneumatic Energy Storage System Considering the Thermodynamic Characteristics

The energy storage system of electric-drive heavy mining trucks takes on a critical significance in the characteristics including excellent load capacity, economy, and high efficiency. However, the existing battery-based system does not apply to harsh cold environments, which is the common working condition for the above trucks. A type of cycle hydro-pneumatic energy storage system for the trucks was proposed in this study. The dynamic model of the system, including the dynamic and thermodynamic models of hydraulic and pneumatic parts, was built to analyze the performance of the system. Subsequently, the thermodynamic characteristics were clarified during the energy storage and released through the real test condition-based simulation. The power and energy performances of the system were studied in practice based on the above characteristics. The analysis of the results showed that the system reduced 22.03% driving power at the optimal braking energy recovery rate, the energy density was nearly 12.6 MJ/m3, the maximum input power was higher than 230 kW, and the cycle efficiency was about 40.6%. The results of this study will be conducive to the application of the hydro-pneumatic energy storage system for the electric-drive mining trucks and reducing the resulting carbon emission

Modelling and Performance Analysis of Cyclic Hydro-Pneumatic Energy Storage System Considering the Thermodynamic Characteristics

The energy storage system of electric-drive heavy mining trucks takes on a critical significance in the characteristics including excellent load capacity, economy, and high efficiency. However, the existing battery-based system does not apply to harsh cold environments, which is the common working condition for the above trucks. A type of cycle hydro-pneumatic energy storage system for the trucks was proposed in this study. The dynamic model of the system, including the dynamic and thermodynamic models of hydraulic and pneumatic parts, was built to analyze the performance of the system. Subsequently, the thermodynamic characteristics were clarified during the energy storage and released through the real test condition-based simulation. The power and energy performances of the system were studied in practice based on the above characteristics. The analysis of the results showed that the system reduced 22.03% driving power at the optimal braking energy recovery rate, the energy density was nearly 12.6 MJ/m3, the maximum input power was higher than 230 kW, and the cycle efficiency was about 40.6%. The results of this study will be conducive to the application of the hydro-pneumatic energy storage system for the electric-drive mining trucks and reducing the resulting carbon emission

9R phase enabled superior radiation stability of nanotwinned Cu alloys via in situ radiation at elevated temperature

Nanotwinned metals exhibit outstanding radiation tolerance as twin boundaries effectively engage, transport and eliminate radiation-induced defects. However, radiation-induced detwinning may reduce the radiation tolerance associated with twin boundaries, especially at elevated temperatures. Here we show, via in-situ Kr ion irradiation inside a transmission electron microscope, that 3 at. % Fe in epitaxial nanotwinned Cu (Cu97Fe3) significantly improves the thermal and radiation stability of nanotwins during radiation up to 5 displacements-per-atom at 200 °C. Such enhanced stability of nanotwins is attributed to a diffuse 9R phase resulted from the dissociation of incoherent twin boundaries in nanotwinned Cu97Fe3. The mechanisms for the enhanced stability of twin boundaries in irradiated nanotwinned alloys are discussed. The stabilization of nano-twins opens up opportunity for the application of nanotwinned alloys for aggressive radiation environments. Includes supplemental Appendix. Video files are attached below