Crystal Reorientation and Amorphization Induced by Stressing Efficient and Stable P-I-N Vacuum-Processed MAPbI3 Perovskite Solar Cells

Herein, the long‐term stability of vacuum‐deposited methylammonium lead iodide (MAPbI3) perovskite solar cells (PSCs) with power conversion efficiencies (PCEs) of around 19% is evaluated. A low‐temperature atomic layer deposition (ALD) Al2O3 coating is developed and used to protect the MAPbI3 layers and the solar cells from environmental agents. The ALD encapsulation enables the MAPbI3 to be exposed to temperatures as high as 150 °C for several hours without change in color. It also improves the thermal stability of the solar cells, which maintain 80% of the initial PCEs after aging for ≈40 and 37 days at 65 and 85 °C, respectively. However, room‐temperature operation of the solar cells under 1 sun illumination leads to a loss of 20% of their initial PCE in 230 h. Due to the very thin ALD Al2O3 encapsulation, X‐ray diffraction can be performed on the MAPbI3 films and completed solar cells before and after the different stress conditions. Surprisingly, it is found that the main effect of light soaking and thermal stress is a crystal reorientation with respect to the substrate from (002) to (202) of the perovskite layer, and that this reorientation is accelerated under illumination

Bilateral effects of unilateral cerebellar lesions as detected by voxel based morphometry and diffusion imaging

Over the last decades, the importance of cerebellar processing for cortical functions has been acknowledged and consensus was reached on the strict functional and structural cortico-cerebellar interrelations. From an anatomical point of view strictly contralateral interconnections link the cerebellum to the cerebral cortex mainly through the middle and superior cerebellar peduncle. Diffusion MRI (dMRI) based tractography has already been applied to address cortico-cerebellar-cortical loops in healthy subjects and to detect diffusivity alteration patterns in patients with neurodegenerative pathologies of the cerebellum. In the present study we used dMRI-based tractography to determine the degree and pattern of pathological changes of cerebellar white matter microstructure in patients with focal cerebellar lesions. Diffusion imaging and high-resolution volumes were obtained in patients with left cerebellar lesions and in normal controls. Middle cerebellar peduncles and superior cerebellar peduncles were reconstructed by multi fiber diffusion tractography. From each tract, measures of microscopic damage were assessed, and despite the presence of unilateral lesions, bilateral diffusivity differences in white matter tracts were found comparing patients with normal controls. Consistently, bilateral alterations were also evidenced in specific brain regions linked to the cerebellum and involved in higher-level functions. This could be in line with the evidence that in the presence of unilateral cerebellar lesions, different cognitive functions can be affected and they are not strictly linked to the side of the cerebellar lesion

An automatically mode-matched MEMS gyroscope with 50 Hz bandwidth

This paper presents the architecture and experimental verification of an automatic mode matching system that uses the phase relationship between the residual quadrature and drive signals in a gyroscope to accomplish and maintain the frequency matching condition. The system also allows controlling the system bandwidth by adjusting the closed loop controller parameters of the sense mode. This study experimentally examines the angle random walk (ARW) and bias instability performances of the fully decoupled MEMS gyroscopes under mismatched (similar to 100Hz) and mode-matched conditions. Moreover, it has been experimentally shown that the performance of the studied MEMS gyroscopes is improved up to 2.4 times in bias instability and 1.7 times in ARW with 50 Hz system bandwidth under the mode-matched condition reaching down to a bias instability of 0.83 degrees/hr and an ARW of 0.026 degrees/root hr

A high performance automatic mode-matched MEMS gyroscope with an improved thermal stability of the scale factor

This paper presents a high performance, automatic mode-matched, single-mass, and fully-decoupled MEMS gyroscope with improved scale factor stability. The mode-matching system automatically achieves and maintains the matching between the drive and sense mode resonance frequencies with the help of dedicated frequency tuning electrodes (FTEs). This method isolates the drive and sense mode frequency response dynamics by keeping the proof mass voltage (V PM ) constant, improving the scale factor stability up to 4.4 times in a temperature range from -20°C to +80°C while maintaining a wide rate bandwidth (above 50 Hz). The presented gyroscope also achieves a very low bias instability of 0.73°/hr and an angle random walk (ARW) of 0.024°/√hr

Dermatitis herpetiformis in a patient receiving infliximab for ankylosing spondylitis [9]

PubMedID: 18086603[No abstract available