[Detection of three metabolites of xylene in urine samples by solid-phase extraction coupled with liquid chromatography-mass spectrometry]

Objective: To establish a method for the rapid determination of the three metabolites of xylene, 2-methylmarmaluronic acid, 3-methylmarmaluronic acid and 4-methylmarmaluronic acid, in urine of occupationally exposed workers by ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS) . Methods: In July 2022, urine samples were diluted and extracted with pH=6.86 phosphate cache solution, cleaned up by a MAX solid-phase extraction (SPE) column and separated by an Accucore Ph/Hexyl column (100 mm×2.1 mm, 2.6 μm) with a gradient of 5 mmol/L ammonium formate-0.1% formic acid aqueous solution and methanol as mobile phases. The analysis was carried out in electrospray ionization mode and full mass-data dependent secondary mass spectrometry mode, and quantified by external standard method. The characteristics of each index of this method were analyzed. Results: A good linearity was obtained in the concentration range of 1.0-200.0 μg/L for 2-methylmuramic acid, 3-methylmuramic acid and 4-methylmuramic acid with the correlation coefficients of 0.9979-0.9993. The limits of detection of the method were 0.18-0.24 μg/L. While the spiked recoveries at the three concentrations (1.0 μg/L, 100.0 μg/L, and 180.0 μg/L) were in the range of 83.0%-93.7%, with the relative standard deviations of 2.2%-7.9%. Conclusion: The UPLC-HRMS method is simple, rapid, sensitive and accurate, and is suitable for the simultaneous determination of the three metabolites of xylene in the urine of occupationally exposed workers.

Diode-pumped passively mode-locked Nd:YVO4 laser at 1342 nm with periodically poled LiNbO3

In this Letter, we demonstrate a nonlinear-mirror (NLM) mode-locked diode-pumped solid-state Nd:YVO4 laser operating at 1342 nm, in which the NLM comprises a periodically poled LiNbO3 crystal and a dichroic mirror. The self-starting threshold for cw mode locking is 1.5 W, which is significantly lower than that of saturable absorber mode locking. An average power of 1.52 W at 1342 nm is obtained under diode pump power of 10 W at 808 nm, with the slope efficiency being up to 16.8%. The pulse width and the repetition rate of the mode-locked laser output are about 9.5 ps and 101 MHz, respectively.

Elevated plasma surfactant protein D (SP-D) levels and a direct correlation with anti-severe acute respiratory syndrome coronavirus-specific IgG antibody in SARS patients

Pulmonary SP‐D is a defence lectin promoting clearance of viral infections. SP‐D is recognized to bind the S protein of SARS‐CoV and enhance phagocytosis. Moreover, systemic SP‐D is widely used as a biomarker of alveolar integrity. We investigated the relation between plasma SP‐D, SARS‐type pneumonia and the SARS‐specific IgG response. Sixteen patients with SARS, 19 patients with community‐acquired pneumonia (CAP) (Streptococcus pneumonia) and 16 healthy control subjects were enrolled in the study. Plasma SP‐D and anti‐SARS‐CoV N protein IgG were measured using ELISA. SP‐D was significantly elevated in SARS‐type pneumonia [median (95% CI), 453 (379–963) ng/ml versus controls 218 (160–362) ng/ml, P < 0.05] like in patients with CAP. SP‐D significantly correlated with anti‐SARS‐CoV N protein IgG (r² = 0.5995, P = 0.02). The possible re‐emergence of SARS or SARS‐like infections suggests a need for minimal traumatic techniques for following the alveolar compartment, e.g. during testing of antivirals. We suggest that monitoring systemic SP‐D may be useful in monitoring the alveolar integrity in SARS‐type pneumonia. The significant correlation between plasma SP‐D and anti‐SARS‐CoV‐specific antibodies support the role for SP‐D in interlinking innate and adaptive immune pathways.

Experimental realization of broadband parametric generation in a quasi-periodically poled LiTaO3

We have achieved broadband parametric generation by using a quasi-periodically poled LiTaO(3) crystal as frequency converter. Tuning wavelength rang from 0.609 microm to 5.208 microm, which covered three quasi-phase-matching processes, was obtained by means of changing the pump wavelength from 0.530 microm to 1.184 microm. The experiment results are in good agreement with theory. The maximum conversion efficiency is 62% with a 10 Hz-5 ns pump source, at the average pump power of 0.5 mW. Our results exhibit a possible application of quasi-periodic superlattice in laser technology.