Search

Temperature greatly influences the activity of biological materials; therefore, it is necessary to simultaneously monitor the temperature and concentration of biological materials. Long-range surface plasmon resonance (LRSPR) sensor has high sensitivity and can detect biomolecules. In this article, we proposed a dual-channel LRSPR sensor that can measure both bovine serum albumin (BSA) concentration and ambient temperature. The proposed sensor used a no-core fiber (NCF) with two channels. One channel was used to deposit magnesium fluoride and silver films on NCF for BSA detection, while the other channel was used to deposit three layers of films [magnesium fluoride, silver, and polydimethylsiloxane (PDMS)] on NCF for temperature detection. The sensitivity of the sensor to detect BSA concentration and temperature is 1.02 nm/(mg/ml) and −2.82 nm/°C, respectively. Cross-sensitivity between the two parameters is solved using a matrix. The sensor offers the advantages of simultaneously monitoring two parameters, having a simple structure and possessing high sensitivity, which makes it promising for a broad range of applications in monitoring BSA concentration and temperature.

In the current context of sustainability development in all countries of the world, the concept of public management has also changed. In order to ensure the construction of a sustainable public management system, the study starts from the environmental Kuznets curve theory. The study analyses the critical point of the highest value of pollution in a certain area and the ecological irreversibility threshold level, in order to ensure sustainable development. It combines a genetic algorithm with a multi-objective particle swarm optimisation algorithm to form the genetic algorithm with multi-objective particle swarm optimisation (GA-MOPSO) algorithm. This algorithm is used to mine and predict two key values in the environmental Kuznets curve (EKC), namely the critical point and its corresponding ecological degradation rate and the ecological irreversibility threshold. The experimental results show that the proposed algorithm achieves an average F1 score of 87.02, an average recall of 65.57% and a cumulative iteration time of 29.04 ms for 60 iterations.

Since the high temperature response characteristics of nematic liquid crystal (NLC) molecules, a compact optical fiber Sagnac loop inserted a segment of NLC film for temperature sensing was proposed and experimentally demonstrated. The NLC film was formed by filling into the micron-scale gap between the two single-mode fibers inserted into a ferrule matching sleeve. After two single-mode patch cables were rotated, the NLC film molecules were oriented due to exogenous effects. Experimental results showed that the temperature sensing performance of the designed sensor was improved by decreasing the thickness of NLC film in Sagnac loop. The thickness of NLC film in the ferrule matching sleeve was measured accurately by Fabry-Perot interference. The wide temperature measurement range of 2.2 ∼ 50.2 °C and a high temperature sensitivity of -9.34 nm/°C were achieved at the NLC film thickness of 31.30 μm. Owing to the compact structure, large measurement range, and high sensitivity, the designed sensor shows a broad application prospect in high spatial resolution and high sensitivity temperature sensing.

Owing to their high sensitivity, surface plasmon resonance (SPR)-based sensors depict broad application prospects in biochemical detection, environmental monitoring, and food safety. In this paper, an optical fiber-based SPR sensor is proposed and demonstrated for the refractive index (RI) detection of liquid samples. This sensor is composed of a multimode fiber (MMF), a no-core fiber (NCF), and another MMF that is connected in sequence. The length of the NCF is 2 cm. A thin silver film is deposited on the NCF surface to stimulate the SPR effect. Experimental results indicated that the shift amount of resonance dip wavelength is as high as 303.6 nm as RI increases from 1.333 to 1.4107. A sensitivity of 2507.58 nm/RIU with a fitting linearity R^2 of 0.9931 is obtained in the lower RI region of 1.333–1.3723, while the sensitivity and R^2 reaches 5228.21 nm/RIU and 0.97395, respectively, in the higher RI region of 1.3723–1.4107. Compared with previously reported RI sensors, the proposed fiber optic SPR sensor exhibits the advantages of simple structure, small volume, low cost, high sensitivity, and wide detection range.

This paper has designed a D-shaped photonic crystal fiber filter based on surface plasmon resonance. The single-polarization filtering performance is analyzed systematically by the finite element method. It is found that the structural optimization process will modify the refractive index of the fundamental mode and the surface plasmon polarization mode, which results in a shift of the resonance wavelength. The proposed filter is able to indicate the wavelength-tunable function in the ranges of 1250–1350 nm and 1550–1750 nm by two methods. Moreover, at the communication windows of 1310 nm and 1550 nm, the corresponding filtering bandwidths are 170 and 550 nm, respectively. The flow chart of filter preparation reported in the study is promising for use in the field of optical devices.

In arid areas, ecological degradation aroused by over-exploitation of fresh water, expansion of artificial oasis and shrinkage of natural oasis, has drawn attention of many scholars and officials. The water and ecological footprints can be used to quantitatively evaluate the water consumption of social-economic activities and their influence on the eco-environments. In addition, increase of the water footprint indicates the expansion of artificial oasis, and the influence on the natural oasis could be reflected by the variation of the ecological footprint. This study was conducted to answer a scientific question that what is the quantitative relationship between the expansion of the artificial oasis and the degradation of the natural oasis in the arid environments of Xinjiang, China. Thus, based on the social-economic data, water consumption data and meteorological data during 2001–2015, we calculated the water and ecological footprints to express the human-related pressure exerted on the water resources and arid environments in Xinjiang (including 14 prefectures and cities), and explore the relationship between the water and ecological footprints and its mechanism by using the coupling analysis and Granger causality test. The results show that both the water and ecological footprints of Xinjiang increased significantly during 2001–2015, and the increasing rate of the ecological footprint was much faster than that of the water footprint. The coupling degree between the water and ecological footprints was relatively high at the temporal scale and varied at the spatial scale. Among the 14 prefectures and cities examined in Xinjiang, the greater social-economic development (such as in Karamay and Urumqi) was associated with the lower coupling degree between the two footprints. Increases in the water footprint will cause the ecological footprint to increase, such that a 1-unit increase in the consumption of water resources would lead to 2–3 units of ecological degradation. The quantitative relationship between the increases of the water and ecological footprints, together with the intensities of water consumption both in the natural and artificial oases of Tarim River Basin, have approved the fact that the formation and expansion of 1 unit of the artificial oasis would bring about the degradation of 2 units of the natural oasis. These conclusions not only provide a technical basis for sustainable development in Xinjiang, but also offer a theoretical guide and scientific information that could be used in similar arid areas around the world.

A high-sensitivity temperature sensor based on gold-coated D-shaped photonic crystal fiber is proposed in this paper. To enhance the sensing performances, gold as the surface plasmon resonance material is coated on the polishing surface. The thermosensitive liquid consists of ethanol and chloroform, and it is placed on the outer layer of the photonic crystal fiber. As the phase-matching condition is satisfied, the core mode couples to the surface plasmon polariton mode, and energy transfer occurs. The influences of the structural parameters on the sensing characteristics were studied using the finite element method. The numerical results show the average sensitivity can reach up to 10.61 nm/°C, and the linearity R^2=0.99341 for the temperature sensing ranges of 0–60°C. Moreover, a good spectral shape can be realized by the proposed fiber. Compared with some previously reported temperature sensors, the proposed temperature sensor shows excellent performances in terms of the sensitivity, detection range, and fabrication.

In this paper, a D-shaped photonic crystal fiber is designed to achieve a single-polarization filter that has a broadband filtering property. The D-shaped structure is a triangular array of air holes, forming a micro-opening on the side-polished surface and plating a gold layer thereon. The investigation of the polarization filter is based on the finite element method; its principle is surface plasmon resonance. The single-polarization filter in the y direction is realized by adjusting parameters such as the apertures of the fiber, the thickness of the gold layer, and the polishing depth. The confinement loss of the core mode in y polarization reaches to a high value of 376.31 dB/cm at 1.55 μm, and that of the x polarization is 0.17 dB/cm; the former is 2225.35 times the latter. When the fiber length L is 1 mm, the crosstalk reaches a peak value of 326.7 dB at 1.55 μm, and the bandwidth of crosstalk higher than 20 dB is 480 nm. In addition, the external gold coating operation is more conducive to application in the manufacturing process. This filter will be an effective application of the optical communication window near 1.55 μm.

We propose a D-shaped photonic crystal fiber (PCF) refractive index sensor with ultrahigh sensitivity and a wide detection range. The gold layer is deposited on the polished surface, avoiding filling or coating inside the air holes of the PCF. The influences of the gold layer thickness and the diameter of the larger air holes are investigated. The sensing characteristics of the proposed sensor are analyzed by the finite element method. The maximum sensitivity can reach 31,000  nm/RIU, and the refractive index detection range is from 1.32 to 1.40. Our proposed PCF has excellent sensing characteristics and is competitive in sensing devices.

The coupling characteristics of a gold-coated side-polished photonic crystal fiber based on surface plasmon resonance are simulated. The resonant points undergo a blue-shift unexpectedly when the refractive indices of the analytes range from 1.32 to 1.50, and a negative sensitivity is observed in the sensing scheme. The wavelength and amplitude are investigated to characterize the device. The highest negative wavelength sensitivity is ?40,400 nm/RIU with a resolution of 2.48 × 10?6RIU, and the corresponding amplitude sensitivity is as high as ?1,246.47 RIU?1with a resolution of 8.02 × 10?6RIU. The sensor shows excellent performance that is comparable to previous reports.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.