In this study, mechanical vibration is used for hydrogen generation and decomposition of dye molecules, with the help of BiFeO3 (BFO) square nanosheets. A high hydrogen production rate of ≈124.1 μmol ...g−1 is achieved under mechanical vibration (100 W) for 1 h at the resonant frequency of the BFO nanosheets. The decomposition ratio of Rhodamine B dye reaches up to ≈94.1 % after mechanical vibration of the BFO catalyst for 50 min. The vibration‐induced catalysis of the BFO square nanosheets may be attributed to the piezocatalytic properties of BFO and the high specific surface area of the nanosheets. The uncompensated piezoelectric charges on the surfaces of BFO nanosheets induced by mechanical vibration result in a built‐in electric field across the nanosheets. Unlike a photocatalyst for water splitting, which requires a proper band edge position for hydrogen evolution, such a requirement is not needed in piezocatalytic water splitting, where the band tilting under the induced piezoelectric field will make the conduction band of BFO more negative than the H2/H2O redox potential (0 V) for hydrogen generation.
Good vibrations! BiFeO3 can serve as a piezocatalyst for hydrogen production by harvesting vibration energy from the environment. The strong piezoelectric field induced by mechanical vibrations tilts the conduction band of BiFeO3, making it more negative than the H2/H2O redox potential, thus enabling hydrogen evolution (see picture).
The fidelity function for quantum states has been widely used in quantum information science and frequently arises in the quantification of optimal performances for the estimation and distinguishing ...of quantum states. A fidelity function for quantum channels is expected to have the same wide applications in quantum information science. In this paper we propose a fidelity function for quantum channels and show that various distance measures on quantum channels can be obtained from this fidelity function; for example, the Bures angle and the Bures distance can be extended to quantum channels via this fidelity function. We then show that the distances between quantum channels lead naturally to a quantum channel Fisher information which quantifies the ultimate precision limit in quantum metrology; the ultimate precision limit can thus be seen as a manifestation of the distances between quantum channels. We also show that the fidelity of quantum channels provides a unified framework for perfect quantum channel discrimination and quantum metrology. In particular, we show that the minimum number of uses needed for perfect channel discrimination is exactly the counterpart of the precision limit in quantum metrology, and various useful lower bounds for the minimum number of uses needed for perfect channel discrimination can be obtained via this connection.
Time is a valuable resource and it is expected that a longer time period should lead to better precision in Hamiltonian parameter estimation. However, recent studies in quantum metrology have shown ...that in certain cases more time may even lead to worse estimations, which puts this intuition into question. In this Letter we show that by including feedback controls this intuition can be restored. By deriving asymptotically optimal feedback controls we quantify the maximal improvement feedback controls can provide in Hamiltonian parameter estimation and show a universal time scaling for the precision limit under the optimal feedback scheme. Our study reveals an intriguing connection between noncommutativity in the dynamics and the gain of feedback controls in Hamiltonian parameter estimation.
A temperature-stabilized 12-bit single-channel successive approximation register (SAR)-assisted pipelined analog-to-digital converter (ADC) running at 1 GS/s with Nyquist signal to noise and ...distortion ratio (SNDR) above 60 dB is presented. The ADC uses a three-stage (4 b-4 b-6 b) SAR-assisted pipeline hybrid architecture to achieve an attractive energy efficiency along with an extended sampling rate. A high-linearity open-loop Gm-R-based residue amplifier (RA) with both complete-settled and dynamic features improves the residue amplification efficiency and speed, while reducing the gain variation over a temperature drift. The inter-stage gain variation over the temperature is compensated through complementary temperature coefficients (TCs) from the inner devices of the RA. Furthermore, a cascade amplification topology in the backend RA alleviates the effect of the input parasitic capacitance to its front-end capacitor DAC (CDAC), thus leading to a small CDAC size to accelerate amplification and conversion. The prototype ADC was fabricated in a 28-nm CMOS process and consumes 7.6 mW from a 1-V power supply at 1 GS/s. The measured inter-stage gain variation is less than 2.3% with a temperature range from 0 °C to 80 °C. The SNDR and SFDR are 60 and 74.6 dB with a Nyquist input, respectively, achieving a Walden figure-of-merit (FoM) of 9.3 fJ/conversion-step and a Schreier FoM of 168.2 dB.
The coefficient of the dimensionally regularized two-loop R3 divergence of (nonsupersymmetric) gravity theories has recently been shown to change when nondynamical three-forms are added to the ...theory, or when a pseudoscalar is replaced by the antisymmetric two-form field to which it is dual. This phenomenon involves evanescent operators, whose matrix elements vanish in four dimensions, including the Gauss-Bonnet operator which is also connected to the trace anomaly. On the other hand, these effects appear to have no physical consequences for renormalized scattering processes. In particular, the dependence of the two-loop four-graviton scattering amplitude on the renormalization scale is simple. We explain this result for any minimally-coupled massless gravity theory with renormalizable matter interactions by using unitarity cuts in four dimensions and never invoking evanescent operators.
Objective
To investigate the safety and feasibility of robot‐assisted single‐port radical prostatectomy using the da Vinci single‐port surgical system.
Methods
This was a prospective phase 1 clinical ...study of prostate cancer patients undergoing robot‐assisted single‐port radical prostatectomy using the da Vinci single‐port surgical system. Primary outcome measures included the conversion rate and 30‐day complications after surgery. Secondary outcome measures included operative time, blood loss, hospital stay, duration of catheterization, final pathological outcomes and number of lymph nodes yielded at pelvic lymphadenectomy.
Results
From February to August 2017, 20 patients were included in the present study. The mean age was 67.7 ± 6.0 years. The mean preoperative prostate‐specific antigen level was 15.3 ± 11.3 ng/mL, and the mean prostate size was 36.6 ± 15.5 mL. Preoperatively, 12 (60%) patients had a Gleason score of 6, four (20%) had a Gleason score of 7 and four (20%) had a Gleason score of 8–10. The mean operative time was 208.9 ± 35.2 min, and the mean blood loss was 296.3 ± 220.7 mL. None of the patients required conversion. The mean hospital stay was 5.0 ± 1.7 days. Among the patients, six (15%) had T2a disease, one (5%) had T2b disease, seven (35%) had T2c disease and nine (45%) had T3a disease on final pathology. A mean number of 8.3 ± 7.1 lymph nodes were yielded at pelvic lymphadenectomy. There were no intraoperative complications. The observed postoperative complications were Clavien grade I–II, and all resolved with conservative management.
Conclusion
Robot‐assisted single‐port radical prostatectomy using the da Vinci surgical system is safe and technically feasible.
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