[Determination of creatinine and 2-thiothiazolidine-4-carboxylic acid in urine by ultra high performance liquid chromatography tandem mass spectrometry].

Objective: To establish an ultrahigh performance liquid chromatography tandem mass spectrometry method for the determination of creatinine (Cre) and 2-thiothiazolidine-4-carboxylic acid (TTCA) in urine. Methods: In October 2020, the end-of-shift urine samples of the monitored subjects were taken, and the filtrate was prepared by centrifugation. After separated by ultra high performance liquid chromatography C18 column, acetonitrile and 0.2% acetic acid aqueous solution were used as mobile phases for gradient elution, the three quadrupole tandem mass spectrometry adopted an electrospray ion source (ESI) , the ion source temperature was 500 ℃ , and the air curtain gas flow rate was 31.4 L/min, qualitative and quantitative analysis of Cre and TTCA were carried out under the multiple reaction monitoring mode. Results: The linear range of Cre was 1.0-1 000.0 µg/L, the linear equation was y=947.3x-1605.6, and the correlation coefficient was 0.9994. The detection limit and the limit of quantitation were 0.3, 1.0 µg/L. When the addition concentrations were 50.0, 150.0 and 450.0 µg/L, the recovery rates were 92.8%-94.6% , the intra assay precisions were 3.6%-5.7% , and the inter assay precisions were 3.4%-5.4%. The linear range of TTCA was 0.1-200.0 µg/L, the linear equation was y=1164.7x-2243.9, and the correlation coefficient was 0.9991. The detection limit and the limit of quantitation were 0.03, 0.1 µg/L. When the addition concentrations were 10.0, 40.0 and 160.0 µg/L, the recovery rates were 90.8%-93.6%, the intra assay precisions were 4.6%-7.4%, and the inter assay precisions were 4.4%-6.9%. Conclusion: The sample pretreatment process of the ultra high performance liquid chromatography tandem mass spectrometry method for the determination of Cre and TTCA in urine is simple, and the continuous determination of Cre and TTCA in urine can be realized only by switching mass spectrometry parameters under the same chromatographic conditions, which is accurate and efficient, and each performance index of the method meets the determination requirements.

Tunneling anisotropic magnetoresistance driven by magnetic phase transition.

The independent control of two magnetic electrodes and spin-coherent transport in magnetic tunnel junctions are strictly required for tunneling magnetoresistance, while junctions with only one ferromagnetic electrode exhibit tunneling anisotropic magnetoresistance dependent on the anisotropic density of states with no room temperature performance so far. Here, we report an alternative approach to obtaining tunneling anisotropic magnetoresistance in α'-FeRh-based junctions driven by the magnetic phase transition of α'-FeRh and resultantly large variation of the density of states in the vicinity of MgO tunneling barrier, referred to as phase transition tunneling anisotropic magnetoresistance. The junctions with only one α'-FeRh magnetic electrode show a magnetoresistance ratio up to 20% at room temperature. Both the polarity and magnitude of the phase transition tunneling anisotropic magnetoresistance can be modulated by interfacial engineering at the α'-FeRh/MgO interface. Besides the fundamental significance, our finding might add a different dimension to magnetic random access memory and antiferromagnet spintronics.Tunneling anisotropic magnetoresistance is promising for next generation memory devices but limited by the low efficiency and functioning temperature. Here the authors achieved 20% tunneling anisotropic magnetoresistance at room temperature in magnetic tunnel junctions with one α'-FeRh magnetic electrode.

Ultra-high order ring resonator system with sharp transmission peaks.

We propose a relay ring resonator structure which comprises multiple cascaded microring resonators, in which the drop waveguide of a microring resonator is also the input waveguide of the subsequent microring resonator, and so forth. Thus, the transmission response of the relay ring resonator structure has sharp peaks, high out-of-band rejection ratios, and long group delays. A relay ring resonator structure comprising 90 microrings is fabricated on silicon nitride wire waveguides. The simulation and experimental results are in good agreement.

Low propagation loss SiN optical waveguide prepared by optimal low-hydrogen module.

We investigated low-hydrogen SiN films prepared by a low temperature (350 degrees C) PECVD method. The impact of SiH(4)/N(2) flow ratio and radio frequency power on the hydrogen content in the SiN films was studied. In this work, we demonstrated a low-loss sub-micron SiN waveguide by using the corresponding optimal SiN films. The propagation loss was found to be as low as -2.1+/-0.2 dB/cm at 1550 nm with waveguide cross-section of 700 nm x 400 nm. The results suggest that the SiN films grown by PECVD with low hydrogen can be used in photonics integrated circuits for new generation communications applications.

[CT brain scanning in the diagnosis and localisation of cerebral schistosomiasis].

CT scanning was performed on 25 cases of cerebral schistosomiasis. The images of the granuloma caused by schistosome eggs showed a high density mass shadow while the edema of the white matter showed a low density shadow. Combining CT scanning, with case history, clinical signs and immunologic assay we could make a correct diagnosis for each of the patients about the pathologic site and nature. The correlations between the images of CT scanning and clinical pathology were analysed and a better treatment regimen was discussed based on our experience. Some of the patients treated with praziquantel and checked by CT scanning showed pathologic changes of the granuloma disappeared during a follow-up period of 3-12 months.