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The industrial x-ray diode with high impedance configuration is usually adopted to generate repetitive x-ray, but its performance would be worsened due to lower electric field on the cathode of diode when a voltage of several hundreds of kV is applied. To improve its performance, a novel metal-ceramic cathode is proposed in this paper. Key factors (width, relative permittivity of ceramic, and so on) affecting electric field distribution on triple points are analyzed by electrostatic field calculation program, so as to optimize the design of this novel cathode. Experiments are done to study the characteristics including emission current of cathode, diode voltage duration, diode mean dynamic impedance, and diode impedance drop velocity within diode power duration. The results show that metal-ceramic cathode could improve diode performance by enhancing emission current and stabling impedance; the impedance drop velocity of diode with spoke-shaped metal-ceramic cathode was reduced to −5 Ω ns−1 within diode power duration, comparing to −15 Ω ns−1 with metal foil cathode. [ABSTRACT FROM AUTHOR]

C19H18Cl2CuN2O2, monoclinic, space group C2/c (no. 15), a = 21.010(3) Å, b = 11.3886(15) Å, c = 7.9578(10) Å, β = 100.725(4)°, V = 1870.8(4) Å3, Z = 4, wR2 = 0.1620, T = 170.0 K. [ABSTRACT FROM AUTHOR]

BACKGROUND: Few studies have compared the clinical efficacy of unilateral and bilateral pedicle screw fixation and fusion in treating atlantoaxial fracture-dislocation. OBJECTIVE: To compare the efficacy of unilateral and bilateral fixation and fusion for atlantoaxial fracture-dislocation and to explore the feasibility of the unilateral surgical procedure. METHODS: Twenty-eight consecutive patients with atlantoaxial fracture-dislocation were included in the study from June 2013 to May 2018. They were divided into a unilateral fixation group and a bilateral fixation group (14 patients in each group with an average age of 43.6 ± 16.3 years and 51.8 ± 15.4 years, respectively). The unilateral group had a unilateral anatomical variation of the pedicle or vertebral artery, or traumatic pedicle destruction. All patients underwent atlantoaxial unilateral or bilateral pedicle screw fixation and fusion. Intraoperative blood loss and operation time were recorded. The visual analog scale (VAS) and Japanese Orthopedic Association (JOA) scoring systems were used to evaluate pre- and postoperative occipital-neck pain and neurological function. X-ray and computerized tomography (CT) were used to assess atlantoaxial stability, the implants' position, and bone graft fusion. RESULTS: All patients were followed up for 39–71 months postoperatively. Intraoperatively, no spinal cord or vertebral artery injury was observed. At the last follow-up, occipital-neck pain and neurological function in the two groups were significantly improved (P < 0.05). The X-ray films and CT showed satisfactory atlantoaxial stability, implant position, and osseous fusion in all the patients at 6 months postoperatively. CONCLUSION: Unilateral and bilateral pedicle screw fixation and fusion can restore atlantoaxial stability and improve occipital-neck pain and neurological function in patients with atlantoaxial fracture-dislocation. The unilateral surgical procedure can be a supplementary option for patients with unilateral abnormal atlantoaxial lesions. [ABSTRACT FROM AUTHOR]

The dead-time effects of single-phase rectifier causes voltage and current distortions, zero-current clamping effects,etc. To solve the problems, the dead-time and zero-current clamping effects were analyzed, and a novel dead time compensation method of single-phase PWM rectifier was proposed by the observation of grid input voltage based on resonant controller phase-looked loop. The new method avoids the noise of the current detection, so that zero-crossing detection is more accurate, and does not cause the phase delay. Comparative analysis was conducted with traditional dead time compensation method based on the current. The proposed scheme can effectively improve the degree of sinusoidal current waveform, and eliminate the need to detect the direction of the current conventional solutions drawbacks. This algorithm is simple and has a practical value. The simulation and experiment results show that the grid input current total harmonic distortion with grid input voltage observation is lower and compensation effect is better. [ABSTRACT FROM AUTHOR]

We introduce lanthanide-doped LiYF upconversion nanoparticles into TiO film and use the obtained composite film to photocatalyze the polymerization of thiophene, developing a polythiophene-TiO heterojunction coupled with upconversion nanoparticles. The upconversion nanoparticles, which are capable of converting long-wavelength photons into shorter ones, aim to broaden the light-harvesting of the heterojunction films. Solar cells are fabricated from the heterojunction films coupled with different contents of upconversion nanoparticles, and measured in respect to the incident photon-electron conversion efficiencies and the current density-voltage curves. It is revealed that the upconversion nanoparticles enable the devices to utilize the long-wavelength photons, and thus, the photovoltaic performances are enhanced. Moreover, by employing Raman spectroscopy, we monitor the process of polymerization on the TiO substrate and put deep insight into the interfacial interaction of the heterojunction. [ABSTRACT FROM AUTHOR]

Accurate, efficient, and reliable measurements of solar photovoltaic (PV) modules are essential for the evaluation and diagnosis of the actual operating status of PV plants. However, current online measurements and extraction models are limited because they do not account for power losses caused by inhomogeneous thermal performance of photovoltaic modules. Accordingly, this paper develops a coupled thermo–electrical loss model to access the power generation, energy losses, and degradation rate of photovoltaic modules with inhomogeneous temperature under actual operating conditions. The experiments indicate that the temperature coefficient of power dissipation and efficiency for solar cells with uneven temperature distribution PV modules are within −0.68W/oC to −0.83 W/°C and −0.46%/oC to −5.81%/oC, respectively. Additionally, the relative error values for the maximum power range from −2.54% to 4.09%, demonstrating the feasibility of the proposed model for predicting the power output behavior of operating PV modules with inhomogeneous temperature distributions. Furthermore, the daily performances of the modules indicate heat and electricity losses ranging from 0.245 kWh to 0.337 kWh, while the ratios of electrical energy dissipation to daily losses vary from 36% to 50%. To ensure the reliability of measuring degradation rates, the solar irradiance thresholds of PV module performance tests are nearly 632W/m2, 781W/m2, 875W/m2, and 875W/m2, respectively. Finally, for the long-term performance valuation, the levelized costs of electricity increase by approximately 0.011 CNY/kWh for every 5% reduction in annual power generation, and the PBP is extended by 4.81yr, 4.22yr, 3.62yr, and 7.10yr, respectively. [Display omitted] • The thermo–electrical model is developed to access power losses of a PV module. • The temperature coefficient of efficiency is within −0.46%/oC to −5.81%/oC. • The relative error of maximum power for the modules ranges from −2.54% to 4.09%. • The ratios of electrical energy dissipation to daily losses vary from 36% to 50%. • Levelized costs of electricity increase by 0.011 CNY/kWh for every 5% reduction. [ABSTRACT FROM AUTHOR]

A compact, low-jitter, and high repetitive rate all-solid-state flash x-ray generator making use of photo conductive semiconductor switches was developed recently for the diagnostic purpose of some hydrokinetical experiments. The generator consisted of twelve stages of Blumlein pulse forming networks, and an industrial cold cathode diode was used to generate intense x-ray radiations with photon energy up to 220 keV. Test experiments showed that the generator could produce > 1 kA electron beam currents and x-ray pulses with ~40 ns duration under 100 Hz repetitive rates at least (limited by the triggering laser on hand), also found was that the delay time of the cathode explosive emission is crucial to the energy transfer efficiency of the whole system. In addition, factors affecting the diode impedance, how the switching synchronization and diode impedance determining the allowable operation voltage were discussed. [ABSTRACT FROM AUTHOR]

We used the photoexcited TiO2films to initiate the copolymerization of 3,4-ethylenedioxythiophenewith pyrrole, aiming to develop an organic/inorganic heterojunction.Specular reflection infrared spectroscopy analysis was used to monitorthe process of polymerization and indicated that the copolymers directlygrew on the TiO2substrate. Dissecting the copolymers withultraviolet photoelectron spectroscopy revealed the evolution of thevalence-band electronic structures. Moreover, the resulting copolymer/TiO2heterojunctions were investigated using electrochemical impedenceand X-ray photoelectron spectroscopy. The Al/poly(3,4-ethylenedioxythiophene-co-pyrrole)/TiO2/ITO heterojunction device thatwas prepared from the hybrid film exhibited a conspicuous rectification.The heterojunction device was also explored with respect to the conductionmodels. [ABSTRACT FROM AUTHOR]

C14H10BrClN2O2, orthorhombic, Pca21 (no. 29), a = 32.4137(12) Å, b = 4.6683(2) Å, c = 8.8873(3) Å, V = 1344.80(9) Å3, Z = 4, Rgt(F) = 0.0239, wRref(F2) = 0.0611, T = 150(2) K. [ABSTRACT FROM AUTHOR]