Determination of Methamphetamine by High-Performance Liquid Chromatography in Odor-Adsorbent Material Used for Training Drug-Detection Animals.

The objective of the present report was to develop and validate a simple, sensitive, and selective analytical method for the determination of methamphetamine in an odor-adsorbent material (gauze) which was used to improve and standardize the training method used for drug-detection animals. High-performance liquid chromatography (HPLC) was performed using a Spherisorb ODS2 C18 column (200 mm × 4.6 mm, 5 µm), with a mobile phase consisting of a 0.25% methanol/triethylamine aqueous solution (V:V = 20:80), the pH of which was adjusted to 3.1 using glacial acetic acid, at a flow rate of 1.0 mL/min. The column temperature was 25 °C, and the detection of the analytes was performed at a wavelength of 260 nm. Methamphetamine showed good linearity (R2 = 0.9999) in the range of 4.2~83.2 mg/mL. The stability of the test material was good over 24 h. The precision of the method was good, with an average spiked recovery of 86.2% and an RSD of 2.9%. The methamphetamine content in the gauze sample was determined to be 7.8 ± 2.2 µg/sample. A high-performance liquid chromatography (HPLC) method was optimized and validated for the determination of methamphetamine in adsorbent materials (gauze). Validation data in terms of specificity, linearity, the limit of detection and the limit of quantification, reproducibility, precision, stability, and recovery indicated that the method is suitable for the routine analysis of methamphetamine in adsorbent materials (gauze) and provided a basis for training drug-detection animals.

Tuning the Magnetic Properties of Cr2TiC2Tx through Surface Terminations: A Theoretical Study.

Recently, magnetic two-dimensional Cr2TiC2Tx MXenes with promising applications in spin electronics have been experimentally confirmed. However, the underlying magnetic mechanism needs to be further investigated. Along these lines, in this work, the magnetic properties of Cr2TiC2On/4F2-n/4 and Cr2TiC2On/4 structures were simulated through first-principle calculations using the GGA+U approach. The values of 4.1 and 3.1 eV were calculated for the Hubbard U of Cr and Ti, respectively, by applying the linear response method. Interestingly, the Cr2TiC2On/4F2-n/4-based configurations with low O content (n ≤ 4) exhibit antiferromagnetic behavior, while the majority of the respective configurations with high O content (n ≥ 5) are ferromagnetic. As far as the Cr2TiC2O5/4F3/4 structure (n = 5) is concerned, the value of about 2.64 µB was estimated for the magnetic moment of the Cr atom. On top of that, the Curie temperature lies within the range of 10~47 K. The extracted theoretical results are in good agreement with experimental outcomes of the Cr2TiC2O1.3F0.8-based structure. From the simulated results, it can be also argued that the magnetic moment of Cr atoms and the Neel temperature can be directly tuned by the active content of O atoms. The conductivity of both Cr2TiC2On/4F2-n/4 and Cr2TiC2On/4 configurations can be regulated by the externally applied magnetic field, while the density of states around the Fermi level shifted significantly between ferromagnetic and antiferromagnetic arrangements. The acquired results provide important theoretical insights to tuning the magnetic properties of Cr2TiC2Tx-based structures through surface termination mechanisms, which are quite significant for their potential applications in spin electronics.

Dendrobium candidum protects against diabetic kidney lesions through regulating vascular endothelial growth factor, Glucose Transporter 1, and connective tissue growth factor expression in rats.

Diabetes mellitus (DM) remains a great health problem with approximate 30% of patients with DM eventually suffering from diabetic nephropathy. The search for exogenous protective factors has recently received wide attention. The current study aimed to investigate the protective effects of Dendrobium candidum (DC) on kidneys in diabetic rats. Initially, streptozotocin-induced diabetic rats were established and randomly divided into the model group, DC group (0.2, 0.4, and 0.8 g/kg) and irbesartan group (17.5 mg/kg). The biochemical indexes, pathological changes, and the expressions of vascular endothelial growth factor (VEGF), GLUT-1, and CTGF were examined. It was found that as compared with the model group, the kidney index, serum creatine, blood urea nitrogen, 24-hour urine protein, and VEGF of DC treatment groups were significantly decreased, and pathological changes in kidney were improved in the DC groups and irbesartan group ( P < 0.05 for each parameter). The protein and messenger RNA levels of GLUT-1 and CTGF in treatment groups were significantly lower than those in rats' renal cortex without treatment. Our data suggest that DC may protect the kidneys of diabetic rats via regulating expression of VEGF, GLUT-1, and CTGF.

The effect of topical atropine on the choroidal thickness of healthy children.

The purpose of the current study was to investigate the effect of topical atropine on choroidal thickness using spectral-domain optical coherence tomography. A total of 30 healthy eyes from 30 children were analyzed in this study. A single drop of 1% atropine gel was administered twice daily for a week. Choroidal thickness (CT) was measured using SD-OCT, and changes in CT before and after administration of the eye drops were analyzed at the subfovea and at 1.0-mm intervals (up to 3.0 mm) from the fovea at superior, inferior, nasal, and temporal locations. Pre- and post-cycloplegic axial length (AL) was also measured using the IOLMaster. We observed that administration of 1% atropine gel led to a significant increase in the choroidal thickness under the fovea and at all intervals from the fovea. The greatest change in CT was observed in the inferior meridian, while the nasal meridian exhibited the least change. AL did not significantly differ before and after cycloplegia, and there was no significant correlation between the changes in AL and subfoveal CT. It was concluded that administration of 1% atropine gel can significantly increase CT in the eyes of young Chinese children, albeit with different magnitude at different locations.