Lead halide perovskite solar cells have recently emerged as a very promising photovoltaic technology due to their excellent power conversion efficiencies; however, the toxicity of lead and the poor stability of perovskite materials remain two main challenges that need to be addressed. Here, for the first time, we report a lead-free, highly stable CHNHCuBrI compound. The CHNHCuBrI films exhibit extraordinary hydrophobic behavior with a contact angle of ∼90°, and their X-ray diffraction patterns remain unchanged even after 4 h of water immersion. UV/vis absorption spectrum shows that CHNHCuBrI compound has an excellent optical absorption over the entire visible spectrum. We applied this copper-based light absorber in printable mesoscopic solar cell for the initial trial and achieved a power conversion efficiency of ∼0.5%. Our study represents an alternative pathway to develop low-toxic and highly stable organic-inorganic hybrid materials for photovoltaic application.

Background:The widespread threat of severe acute respiratory syndrome (SARS) to human life has spawned challenges to develop fast and accurate analytical methods for its early diagnosis and to create a safe antiviral vaccine for preventive use. Consequently, we thoroughly investigated the immunoreactivities with patient sera of a series of synthesized peptides from SARS-coronavirus structural proteins. Methods: We synthesized 41 peptides ranging in size from 16 to 25 amino acid residues of relatively high hydrophilicity. The immunoreactivities of the peptides with SARS patient sera were determined by ELISA. Results: Four epitopic sites, S599, M137, N66, and N371-404, located in the SARS-coronavirus S, M, and N proteins, respectively, were detected by screening synthesized peptides. Notably, N371 and N385, located at the COOH terminus of the N protein, inhibited binding of antibodies to SARS-coronavirus lysate and bound to antibodies in >94% of samples from SARS study patients. N385 had the highest affinity for forming peptide-antibody complexes with SARS serum.

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The turning point of the refractive index (RI) sensitivity based on the multimode microfiber (MMMF) in-line Mach-Zehnder Interferometer (MZI) is firstly observed.By tracking the resonant wavelength shift of the MZI generated between HE11 and HE12 modes in the MMMF, the surrounding RI (SRI) could be detected. Theoretical analysis demonstrates that the RI sensitivity will be reached to ±∞ on either side of the turning point due that the group effective RI difference (G) approaches to zero. Significantly, the positive sensitivity exists in a much wide fiber diameter range while the negative sensitivity can be achieved in a narrow diameter range of only 0.3μm. Meanwhile, the experimental sensitivities and variation trend at different diameters exhibit high consistency with the theoretical results. High RI sensitivity of 10777.8nm/RIU at the fiber diameter of 4.6μm and the RI around 1.3334 is realized. The discovery of the sensitivity turning points has great significance on trace detection due to the possibility of ultra-high RI sensitivity. © 2015 Optical Society of America http://dx.doi.org/ XXXX /OL. XX. XXXX XX Fiber-based sensors have been widely investigated for the measurement of chemical and biomedical parameters due to their unique merits, such as compact size, electromagnetic interference immunity, potential low cost, and usage in harsh environment [1][2][3][4][5]. Especially, ultra-high sensitive refractive index (RI) fiber sensors are significant for biochemical trace detection. When the fiber is surface immobilized with functional materials, it can realize selective and accurate biochemical identification [6][7][8].Recently, the microfiber, with promising optical properties of large evanescent field, low transmission loss, high nonlinear effect, and tight optical confinement, has become attractive in photonics fields [9][10][11][12][13]. One kind of microfiber i.e. multimode microfiber (MMMF), also called non-adiabatic tapered fiber, is simply fabricated through tapering a conventional single mode fiber (SMF) into micrometer size. Different from the adiabatic tapered fiber, the MMMF has a much larger transition angle [19], resulting in the excitation of few guided modes inthe transition region. Then, an in-line Mach-Zehnder interference (MZI) is generated in only one standard microfiber due to the interference between the two dominant modes. MMMF has shown outstanding performance in refractive index (RI) sensing with high sensitivity of 10 3 ～10 4 nm/RIU [20][21][22] and temperature sensing with the sensitivity up to -3.88nm/ o C [22]. However, to the best of our knowledge, systematic investigation on the sensing performance of the MMMF based in-line Mach-Zehnder interferometer (MZI) especially the RI sensitivity characteristics has not been reported.In this letter, we establish the RI sensing modal and systematically analyze the sensitivity of the MMMF based in-line MZI. By comprehensively calculating the effective RI of the supporting modes, the mode field distribution, and the group effective RI diff...

An improved algorithm named "twice-FFT" for multi-point intrusion location in distributed Sagnac sensing system is proposed and demonstrated. To find the null-frequencies more accurately and efficiently, a second FFT is applied to the frequency spectrum of the phase signal caused by intrusion. After Gaussian fitting and searching the peak response frequency in the twice-FFT curve, the intrusion position could be calculated out stably. Meanwhile, the twice-FFT algorithm could solve the problem of multi-point intrusion location. Based on the experiment with twice-FFT algorithm, the location error less than 100m for single intrusion is achieved at any position along the total length of 41km, and the locating ability for two or three intrusions occurring simultaneously is also demonstrated.

A novel microstructure based temperature sensor system using hybrid wavelength-division-multiplexing /frequency-division-multiplexing (WDM/FDM) is proposed. The sensing unit is a specially designed microstructure sensor both frequency and wavelength encoded, as well as low insertion loss which makes it have the potential to be densely multiplexed along one fiber. Moreover, the microstructure can be simply fabricated by UV light irradiation on commercial single-mode fiber. Assisted with appropriate demodulation algorithm, the temperature distribution along the fiber can be calculated accurately. In theory, more than 1000 sensors can be multiplexed on one fiber. We experimentally demonstrated the feasibility of the scheme through building a sensor system with 9 microstructures multiplexing and with temperature resolution of 0.4°C.

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