Urea additive improves the performance of low bandgap tin-lead perovskite solar cells.

Recently, narrow bandgap tin-lead mixed perovskite solar cells (PSCs) have become a research hotspot because they can be applied in tandem cells to break the Shockley-Queisser radiative limit of the single junction PSCs. However, the introduction of tin, on the one hand, makes the crystal quality of perovskite thin film worse, leading to the increase of film defects; on the other hand, the easy oxidation of divalent tin also leads to the increase of defect states, which seriously affects the photoelectric conversion efficiency of tin-lead cell devices. Good crystallization and low defect density of perovskite layer are very important to ensure good light absorption and photogenerated carrier generation and transport. Here, we adjust the crystallization of tin-lead perovskite films by a Lewis base-urea (CO(NH2)2), which significantly increases the grain size and improves the film morphology. At the same time, because of the Lewis base property of urea, the uncoordinated Pb2+and Sn2+defects of Lewis acids in the tin-lead films are effectively passivated, and the occurrence of non-radiative recombination in the films is reduced. Under the dual effects of improving crystallization and passivating defects, the photoelectric performance of tin-lead perovskite solar cell devices is significantly improved to 18.1% compared with the original device of 15.4%.

Assessment of the characteristics and quality of life of patients with uremic peripheral neuropathy
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OBJECTIVES: This study seeks to examine the characteristics and health-related quality of life (HRQL) of patients with uremic peripheral neuropathy. METHODS: Uremic patients undergoing maintenance hemodialysis (MHD) at our hospital were enrolled in this study. Data collection began in January 2011 and ended in June 2011. The patients were divided into two groups, the lesion group (110 cases) and the non-lesion group (168 cases), based on the presence or absence of peripheral neuropathy. To examine continuous changes in signs and symptoms in the lesion group, electromyography (EMG) was performed to measure sensory nerve conduction velocity (SCV), motor nerve conduction velocity (MCV), and distal latency (DL). Furthermore, HRQL was analyzed using the generic Short Form-36 (SF-36) questionnaire. RESULTS: Numbness and a burning sensation in the distal limbs were observed in the lesion group; in particular, these phenomena occurred in the upper limbs and the lower limbs in 3.6% (4/110) and 48.2% (53/110) of patients, respectively. With respect to motor symptoms, upper and lower limb weakness was observed in 1.8% (2/110) and 11.8% (13/110) of patients, respectively. Changes in physical signs were mainly evidenced by tendon reflexes, for example, areflexia, or tendon reflex loss was detected in the upper extremities, the knee tendon, and the Achilles tendon in 9.09% (10/110), 55.45% (61/110), and 35.5% (39/110) of patients, respectively. Relative to the non-lesion group, the lesion group had significantly slower average SCV and MCV as well as a longer average DL (p < 0.01 for all comparisons). Based on a clinical statistical analysis of SF-36 reports, scores on each scale were lower in the lesion group than in the non-lesion group. However, compared with the non-lesion group, the lesion group did not significantly differ with respect to overall SF-36 score (t = 1.896, p = 0.060) but did significantly differ with respect to bodily pain score (t = 5.301, p < 0.001). CONCLUSIONS: Typical symptoms of uremic peripheral neuropathy include numbness of the limbs and changes in tendon reflexes. In this study, sensory nerves were damaged more severely than motor nerves, and lower extremity lesions were more frequent than upper limb lesions. Clinicians should devote greater attention to patients with uremic peripheral neuropathy and strive to continuously improve these patients' quality of life.
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Efficient Air-Processed MA-Free Perovskite Solar Cells by SH-Based Silane Interface Modification.

Air-processed perovskite solar cells (PSCs) with high photoelectric conversion efficiency (PCE) can not only further reduce the production cost but also promote its industrialization. During the preparation of the PSCs in ambient air, the contact of the buried interface not only affects the crystallization of the perovskite film but also affects the interface carrier transport, which is directly related to the performance of the device. Here, we optimize the buried interface by introducing 3-mercaptopropyltrimethoxysilane (MPTMS, (CH3O)3Si(CH2)3SH) on the nickel oxide (NiOx) surface. The crystallization of the perovskite film is improved by enhancing surface hydrophobicity; besides, the SH-based functional group of MPTMS passivates the uncoordinated lead at the interface, which effectively reduces the defects at the bottom interface of perovskite and inhibits the nonradiative recombination at the interface. Moreover, the energy level between the NiOx layer and the perovskite layer is better matched. Based on multiple functions of MPTMS modification, the open circuit voltage of the device is obviously improved, and efficient air-processed methylamine-free (MA-free) PSCs are realized with PCE reaching 21.0%. The device still maintains the initial PCE of 85% after 1000 h aging in the glovebox. This work highlights interface modification in air-processed MA-free PSCs to promote the industrialization of PSCs.

Escape over a fluctuating potential barrier with three-state Markovian noise.

We consider the escape over a fluctuating potential barrier with a three-state Markovian noise. The resonant activations (RA's) for the mean first-passage times as functions of the transition rates gamma(1), gamma(2), and gamma(3) of the three-state Markovian noise are obtained, respectively. The effect of the three values of the three-state Markovian noise on the RA's is investigated.

Phenomenon of stochastic resonance caused by multiplicative asymmetric dichotomous noise.

The exact expression of the first moment and the signal-to-noise ratio (SNR) have been calculated for a linear system subject to an external periodic field as well as a multiplicative asymmetric dichotomous noise, by using the Shapiro-Loginov formula. It has been found that the amplitude of the output signal, and the SNR, respectively, exhibit two kinds of the phenomena of stochastic resonance: one is as the functions of the parameters of the asymmetric dichotomous noise, such as the noise strength D, and the parameter k describing the asymmetric degree of the dichotomous noise; the other is as the function of the parameter of the input signal, such as the input signal frequency omega.