Search

In this paper, a low loss jammed-array wideband sawtooth (JAWS) filter is built based on a finite reflection virtually imaged array (FRVIA) which has a lower reflectivity of the exit surface compared to a virtually imaged phased array (VIPA). This filter can be used as an edge filter to interrogate the fiber Bragg grating (FBG) sensors. A fast FBG sensing system is set up to detect the strain wave of iron pipe to demonstrate the use of this interrogator. The result shows that the JAWS based interrogation system has advantages of high speed, low loss and high sensitivity.

Pollutants in water seriously threaten the health of human beings and will lead to potential ecological risks to the aquatic environment. Researchers use many chemical, physiological and morphological methods to detect the comprehensive toxicity in water. Among them, the photosynthetic inhibition method is considered a powerful method to detect the comprehensive toxicity in water, takes the chlorophyll fluorescence in the body as a natural probe, and determines the toxicity effect of pollutants by measuring the variation of photosynthetic fluorescence parameters. It has the advantages of fast and convenient measurement and real-time online detection. The widely used photosynthetic fluorescence parameters are the maximal quantum yield of photosystem II (Fv/Fm) and performance index PIABS. There are the problems that the sensitivity is not high enough, and the substances that can be detected are limited when researchers use Fv/Fm and PIABS as indicators to detect the comprehensive toxicity in water. So, in this paper, we proposed a construction method of Performance Index of Comprehensive Toxicity Effect (PICTE) using multi-parameter fusion based on the chlorophyll a fluorescence rise kinetics curve (OJIP) of algae. The fluorescence information of point J and point I in the curve was integrated. The area surrounded by the curve and the time corresponding to point J and point I were weighted for data items to construct PICTE. On this basis, Chlorella vulgaris was used as the tested algae species to compare the performance differences of Fv/Fm, PICTE, PIABS in the detection of toxic substances under the stress of five common water pollutants: Diuron (DCMU, 3-(3,4-dichlorophenol)-1,1-dimethylurea), Dibromothymoquinone (DBMIB, 2,5-dibromo-3-methyl-6-isopropyl-benzoquinone), Methyl viologen (MV, 1,1ꞌ-dimethyl-4,4ꞌ-bipyridinium-dichloride), Malathion, Carbofuran. The performance differences of Fv/Fm, PICTE, PIABS in detecting toxic substances, including lowest detection limit, highest response concentration, stability, and reproducibility, were studied. The results show that: in terms of toxicity detection, the constructed PICTE was sensitive to all five toxic substances and could detect more kinds of pollutants than Fv/Fm. The lowest detection limit of PICTE for five toxic substances compared with PIABS was reduced by 74.43%, 77.01%, 67.30%, 60.69%, and 50.81%, respectively. At the same time, it has a stronger ability to detect toxic substances with high concentration. The stability and reproducibility of PICTE for detecting the toxicity of DCMU, DBMIB, Malathion, and Carbofuran were all excellent, and all of the relative standard deviation (RSD) was

Determining the residual field in a magnetic shield is essential in quantum measurement. However, it faces some problems which limit the measuring accuracy. In order to overcome the main problems for the measuring method based on magnetic resonance, a method which detects the electron paramagnetic resonance frequency of 133Cs atoms is reported. By using a rotating exciting magnetic field and choosing appropriate frequency of probe light, the influences of the Bloch-Siegert effect on the measurement of the residual field is eliminated, and by extracting the sums of the residual field and the fictitious field caused by light shifts under different pump light powers and using a second-degree polynomial fitting, the influences of light shifts on the measurement of the residual field is eliminated, thus the residual field is obtained accurately. The test results demonstrate that a high measuring accuracy of 0.01 nT can be achieved for this method.

When the influence of hyperfine structure is ignored for atomic magnetometers, it will lead to considerable measuring errors in some cases. Considering the Cs hyperfine structure, an analytical form of magnetic resonance spectrum of the exciting-field frequency response is obtained through theoretical derivation, which is verified by the experiment. Based on the results of the experimental scheme, the optimal frequency and intensity of pump light for a Cs atomic magnetometer with well-resolved magnetic resonance spectrum are found. Additional applications in minimizing the measuring error of atomic magnetometers and the study of optical pumping are explored.

A highly sensitive strain and temperature sensor which is formed by concatenating a fiber Bragg grating (FBG) with a section of PANDA polarization-maintaining fiber (PMF) in a fiber loop mirror (FLM) has been proposed and experimentally demonstrated to perform temperature and strain measurement. The sensing principle of high birefringence fiber loop mirror (HiBi-FLM) and FBG has been analyzed with formula derivation. Due to the different temperature and strain sensitivities of HiBi-FLM resonant dip and FBG resonant peak, the changes in applied strain and ambient temperature can be simultaneously determined by measuring the two resonance wavelengths shifts. High temperature sensitivity of −1.93 nm/℃ and strain sensitivity of 37.5 pm/μe have been achieved respectively over the range of 20∼55 ℃ and 0∼789.6 μe. The discrimination errors for temperature and strain are measured to be ± 0.5 ℃ and ± 18 μe, respectively. The proposed sensor enjoys simple structure, good linearity, high sensitivity and low cost, and thus shows a good application prospects in various fiber-optic sensing applications.

Optically pumped rubidium atomic magnetometer with elliptically polarized light is demonstrated theoretically and experimentally. Compared with the conventional optical absorption detection mode, the sensitivity of atomic magnetometer for this detection mode can be improved by an order of magnitude under our experimental condition. Some parameters that influence the performance of this magnetometer is studied, which are the form of elliptically polarized light, the amplitude of exciting magnetic field, and the laser intensity. The sensitivity of 2.5 pT/√Hz is obtained when these parameters are optimized.

Infections strongly reduce the success rate of implant-related medical procedures. The incorporation of anti-bacterial implant coatings can reduce the chance of infection. However, most of these coatings do not repel bacteria, such that dead bacteria stay on the surface and the performance of these coatings degrades. Ideally, implant coatings should repel bacteria and inhibit bacterial growth in the event of attachment. Unfortunately, the preparation of such coatings often involve complex and expensive synthesis steps, or rely on antibiotics. In this article, we present a simple, inexpensive and robust technique to prepare implant coatings without the use of antibiotics. Our coatings have both anti-fouling and anti-bacterial properties, such that bacteria do not stick to the implant surface and are killed when they come into contact. The coating is composed of poly(3-sulfopropyl methacrylate potassium salt) (Cu@PSPMAK) polymer brushes doped with copper ions (Cu2+). The Cu2+ in the Cu@PSPMAK coating enables an excellent antibacterial efficiency against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), while the PSPMAK polymer brushes in the coating effectively repel the (dead) bacteria. We show using both in vitro and in vivo tests that the Cu@PSPMAK coating is indeed very effective in avoiding implant-related infections. Moreover, the tests show that the Cu@PSPMAK coating is also biocompatible and accepted within the body. All this makes the Cu@PSPMAK coating an ideal solution for combatting bacterial infections at implants.

A global aging population, normally accompanied by a high incidence of aging-associated diseases, has prompted a renewed interest in basic research on human aging. Although encouraging progress has been achieved using animal models, the underlying fundamental mechanisms of aging remain largely unknown. Here, we review the human induced pluripotent stem cell (hiPSC)-based models of aging and aging-related diseases. These models seek to advance our knowledge of aging molecular mechanisms and help to develop strategies for treating aging-associated human diseases.