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[Display omitted] • Low-release biochar (BC-LR) can promote microbial autotrophic metabolism. • BC-LR can adsorb microbial metabolites to reduce its feedback inhibition effect. • BC-LR can selectively adsorb the main inhibitory components in metabolites. • Without low release characteristics, biochar may inhibit microbial CO 2 fixation. • BC-LR has the advantages of high cost-effective and biocompatibility in application. Chemoautotrophs, the crucial contributors to biological carbon fixation, derive energy from reducing specific inorganic substances and utilize CO 2 for growth. However, the release of extracellular free organic carbon (EFOC) by chemoautotrophic microorganisms can inhibit their own growth and metabolism. To reduce the feedback inhibition effect, a low-release biochar (BC-LR) was applied to adsorb EFOC. BC-LR not only adsorbed EFOC, but also selectively adsorbed the main inhibitory component, low molecular weight organics, in EFOC. In contrast, ordinary biochar could not effectively adsorb EFOC and its addition inhibited microbial growth and CO 2 fixation. In Transwell culture, BC-LR promoted microbial growth by 190% and CO 2 fixation by 29%, and exhibited better economic advantage, when compared with granular activated carbon. These findings provide a novel insight into the interaction between biochar and autotrophic microbial metabolism, offering an economically feasible approach to mitigate feedback inhibition of metabolites and promoting biological CO 2 fixation. [ABSTRACT FROM AUTHOR]

Highlights • The proposed PCF filter can realize three kinds of filtering effects. • Two ultra-large air holes makes the process of plating gold film more convenient. • Ultra-high crosstalks and losses can be obtained at the communication windows. • The filtering bandwidth can reach 700 nm at the communication window of 1550 nm. Abstract In this study, we present a single-polarization photonic crystal fiber filter. The metallic gold is used as the surface plasmon resonance activity material, which is deposited on the inner wall of the two ultra-large holes. The properties of the photonic crystal fiber filter are investigated by the finite element method. By adjusting the structural parameters and gold film thickness, three kinds of filtering effects can be obtained at the communication windows. When the length of the optical fiber is 1 mm, one of the filtering effects can achieve loss of 588.900 dB/cm at the communication window of 1310 nm, and the corresponding filtering bandwidth equals to 270 nm; the other two kinds of filtering effects can be applied to the communication window of 1550 nm, and the losses are 569.682 and 971.330 dB/cm and the corresponding filtering bandwidths equal to 700 and 630 nm, respectively. The proposed photonic crystal fiber filter shows great advantages compared with some previous reports on filtering. [ABSTRACT FROM AUTHOR]

• A novel SPR sensor based on D-shaped PCF with offset-core is proposed and demonstrated for the liquid RI measurement. • The structural design of the D-shaped fiber makes the placement of the liquid to be tested more convenient. • The SPR sensor with high sensitivity can be realized by introducing the offset-core. • Ultra-high wavelength sensitivity and amplitude sensitivity of 42,000 nm/RIU and 2204.49 RIU−1 are obtained. We propose a novel D-shaped offset-core photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) for the liquid refractive index (RI) measurement. The D-shaped structural design makes the placement of the liquid to be tested more convenient. The offset-core is designed to improve the sensitivity of the SPR sensor. The optical propagation characteristics of the proposed sensor were investigated by the finite element method (FEM). Numerical results show that more energy of the core mode transfers to the gold surface as the analyte RI increases. The wavelength sensitivity increases with the increase of RI, and the maximum wavelength sensitivity can reach to 42,000 nm/RIU. What's more, the maximum amplitude sensitivity is up to 2204.49 RIU−1. The proposed sensor shows excellent performances in terms of wavelength sensitivity and amplitude sensitivity than some previous reported sensors. We believe that it can become a favorable competitor in the liquid RI measurement fields. [ABSTRACT FROM AUTHOR]

Abstract: Zirconacyclopentenes, which are easily prepared from alkynes and EtMgBr (or ethylene) and Cp2ZrCl2, reacted with oxalyl chloride in the presence of catalytic amount of CuCl to give cyclopentenones in high yields. The reaction was performed conveniently in one pot from alkynes, EtMgBr, oxalyl chloride, and Cp2ZrCl2. [Copyright &y& Elsevier]

• An optical fiber sensor combining the Sagnac interference and modal interference was fabricated and experimentally investigated for the measurements of liquid level and strain. • A sensitivity of 525 pm/mm for liquid level detection, and 32 pm/με for strain detection were obtained. • This sensor has advantages of simple structure, high sensitivity and good accuracy, which is an ideal candidate of liquid level and strain simultaneous detection. An optical fiber sensor for the detections of strain and liquid level was experimentally investigated in this paper. This sensor was fabricated through cascading the Sagnac interference (SI) and multi-mode interference (MMI). A construction of single mode fiber-no core fiber-single mode fiber (SMF-NCF-SMF) was used to excite the MMI, while a section of 10.0 cm long Panda polarization maintaining fiber (PMF) was utilized to generate the polarization modes interference in the Sagnac loop. Two interference valleys corresponding to the MMI and SI appeared in the transmission spectrum and were utilized to detect the liquid level and strain, respectively. The measurement sensitivity of liquid level is higher than most of the reported sensors. This designed sensor could become a good candidate for the liquid level and strain detection owing to the simple structure, high sensitivity, and low hysteresis effect. [ABSTRACT FROM AUTHOR]

A narrowband dual-polarization filter based on photonic crystal fiber (PCF) with Au-Ag double-layer films is proposed. The cladding of PCF is composed of three layers of air holes, and Au-Ag double-layer films are coated on two symmetrical air holes to excite surface plasmon resonance (SPR) effect. The special mechanism of the Au-Ag double-layer films takes advantage of the narrower full width at half maximum (FWHM) of silver. On the other hand, gold is used to protect the silver from oxidation and improve the stability of the filter, and can also enhance SPR effect. The simulation results show that the dual-polarization filter with double-layer metal films has higher resonance absorption and better spectra than that with the single-layer metal film. When the thickness of the double-layer metal films is 22.5 nm (the thickness of silver film is 18 nm), the confinement loss of dual-polarization filter at 1430 nm is achieved to 64.08 dB/cm (y-pol core mode) and at 1530 nm is achieved to 37.26 dB/cm (x-pol core mode). The wavelength range of crosstalk (CT) greater than 20 dB and less than −20 dB are 1410–1450 nm and 1510–1550 nm for the device length of 10 mm, respectively. The CT is achieved 555.07 dB and −321.54 dB at the wavelength of 1430 nm and 1530 nm, respectively. These characteristics show that the filter has excellent performance, and will become a suitable candidate for a narrowband polarization filter. [ABSTRACT FROM AUTHOR]

In this paper, a dual-polarizated photonic crystal fiber filter (PCF) based on surface plasmon resonance (SPR) was proposed. Its polarization characteristics were numerically researched by finite element method (FEM). The results indicate that the polarization filtering of the filter be able to fulfill in dual communication bands of 1310 and 1550 nm. The confinement loss reaches 80,711.4 dB/m for the x polarization core mode at the wavelength of 1310 nm, while 46,614.5 dB/m for the y polarization core mode at the wavelength of 1550 nm. When the length of PCF is 2.5 mm, the extinction ratios of x and y polarization core modes can achieve 1705.27 and − 883.46 dB, respectively. For the communication windows of 1310 and 1550 nm, the filtering bandwidths can reach to 390 and 350 nm, respectively. These excellent characteristics are beneficial to the design and manufacture of filter devices. • A PCF dual windows polarization filter based on SPR is proposed. The square arrangement of air holes is easy to prepare. • The losses of the filter at dual windows can reach 80,711.4 dB/m and 46,614.5 dB/m. • When L PCF = 2.5 mm, the ER of the two orthogonal modes can reach 1705.27 and − 883.46 dB. The bandwidth can reach 390 nm and 350 nm. [ABSTRACT FROM AUTHOR]

• An ultrahigh-sensitive fiber-optic temperature sensor based on cascaded Sagnac interferometers with a nematic liquid crystal film was proposed and experimentally demonstrated. • The molecules of NLC film changed from isotropic to isotropic just by rotating the two single-mode patch cables without any orientation agent, electric, or magnetic devices. • Experimental results revealed that the temperature sensor based on the cascaded configuration showed an ultrahigh sensitivity of 43.13 nm/°C, which was amplified about 5 times contrast to a single Sagnac interferometer. We demonstrated an ultrasensitive fiber-optic temperature sensor based on cascaded Sagnac interferometers (CSIs). One of the Sagnac interferometers (SIs) consisted of a panda polarization-maintaining fiber (PMF) as the reference arm, while the other one contained two single-mode patch cables in a ferrule matching sleeve as the sensing arm, where a nematic liquid crystal (NLC) film was infiltrated into the micron-scale gap of the sleeve. In the sensing SI, the orientation of NLC film was induced by just rotating the two single-mode patch cables without any orientation agent, electric, or magnetic devices. Vernier effect was acquired by adjusting the thickness of NLC film. Experimental results revealed that the temperature sensitivity of the CSIs was up to 43.13 nm/°C, which was enhanced about 5 times compared to the single NLC SI. The designed optical fiber temperature sensor possessed the merits of compact structure, high stability, ultrahigh sensitivity, low hysteresis effect and high resolution, showing a promising application prospect in some scientific filed requiring accurate temperature measurement, such as biomolecules, medicine and other filed. [ABSTRACT FROM AUTHOR]

• A bubble microcavity in an ultra-thin core optical fiber was fabricated to form a Fabry-Perot interferometer. • The size of the bubble decreased gradually with further arc discharges, which was inverse to the reported literature. • The bubble microcavity in the ultra-thin core optical fiber showed a strain sensitivity of 2.08 pm/με and a gravity sensitivity of 2.908 nm/N in a large measurement range. • The bubble microcavity in the ultra-thin core optial fiber was insensitive to temperature and bending, which was benefit to avoid the cross influences. Recent progress in optical fiber sensors based on Fabry-Perot interferometers (FPIs) has achieved much attention. In this paper, we designed and fabricated an FPI sensor by building a bubble in an ultra-thin core optical fiber. The size of the bubble decreased gradually with further arc discharges, which was inverse to the bubble fabrication in standard single mode fibers and multimode fibers. The bubble microcavity in the ultra-thin core optical fiber demonstrated a strain sensitivity of 2.08 pm/με in the range of 0–5000 με and a gravity sensitivity of 2.908 nm/N in the range of 0–4.89 N with high linear responses. Meanwhile, the bubble microcavity sensor was insensitive to temperature and bending, which was benefit to avoid the cross influences. The FPI sensor based on a bubble microcavity in an ultra-thin core optical fiber possesses the properties of easy to fabricate, small size, robustness, and high sensitivity. [ABSTRACT FROM AUTHOR]

• The D-shaped microstructure fiber sensor is suitable for external plasmonic sensing. • The fiber sensor performs sensing detection by means of double resonance peaks. • The fiber sensor has high sensitivity, high resolution and high figure of merit at the near-infrared wavelength. • Double-peaks detection is simultaneously self-calibrated as both detection and verification. A miniature D-shaped microstructure fiber sensor is proposed for external plasmonic sensing. The hollow core not only effectively modulates the core field, but also efficiently facilitates the excitation of surface plasmon resonance near the micro-opening. The refractive indices of analyte ranging from 1.37 to 1.41 can be detected by double-loss peaks tracing in the near-infrared wavelength. And the more reliable method of double-peaks detection achieves detection and verification simultaneously, which improves largely the accuracy of sensing detection. In addition, the transmission properties and sensing characteristics for the designed sensor is explored as well corresponding to various geometrical parameters. An average wavelength sensitivity is 26,927 nm/RIU with the resolution of 3.71 × 10−6 RIU, and the maximum amplitude sensitivity of 5059 RIU−1 is obtained with the resolution of 1.97 × 10−6 RIU, moreover, the maximum figure of merit can reach to 1282, which can be found a wide application prospect in the field of chemical, biological and medical. [ABSTRACT FROM AUTHOR]

A dual-polarized microstructure fiber sensor is based on surface plasmon resonance, which is arranged of pentagonal lattice to achieve refractive index sensing in the near-infrared spectrum. The gold nanowire-filled fiber sensor exhibits excellent sensing characteristics and improved transmission properties. Finite element method is used for computational analysis and structural optimization for the fiber sensor. When the refractive index of the analyte range from 1.32 to 1.38, dual-polarizd sensing can be implemented as a self-calibration with wavelengths increasing from 700 to 1200 nm. For the proposed sensor, the highest wavelength sensitivity of 10,286 nm/RIU is exhibited with a sensor resolution of 9.72×10−6 RIU, and the corresponding amplitude sensitivity and figure of merit are as high as 544.0 RIU−1 and 146.9. Moreover, the sensing length of at least 1.14 mm ensures accurate detection of optical signals for proposed sensor. Owing to the above advantages, the proposed sensor is suitable for high integration and high precision sensitivity detection. [ABSTRACT FROM AUTHOR]

We propose a Sagnac interferometer (SI) based on ethanol-filled photonic crystal fiber (PCF) with two ultra-large holes for temperature measurement. The phase birefringence of the fully-filled PCF varies significantly with the temperature which is realized by infiltrating ethanol into air-holes. Two ultra-large holes in y direction near the core result in a high birefringence of PCF. By selecting a fiber length of 2.5 cm, the average sensitivity of temperature can be up to -34 nm/°C with a resolution of 0.00029 °C in the wavelength range of 780 nm–2170 nm within temperature variation of 40 °C. The proposed PCF with the simple structure is easy to prepare in the experiment. Furthermore, due to the ultrahigh-sensitivity, the proposed sensor provides a new implementation for accurately temperature measurement. [ABSTRACT FROM AUTHOR]