A lead-free Cs2ZnCl4 perovskite nanocrystals fluorescent probe for highly selective detection of norfloxacin.

The abuse of antibiotics would seriously affect human health and has become of worldwide critical concern, thus it is urgent to develop an environmentally friendly and nontoxic fluorescent probe for antibiotics sensing. In this work, a lead-free Cs2ZnCl4 perovskite nanocrystals (PNCs) probe was fabricated for sensing norfloxacin (NOR) employing a modified ligand-assisted reprecipitation method. The prepared Cs2ZnCl4 PNCs probe had strong blue emission around 440 nm, and the characteristics of PNCs were systematically characterized by X-ray photoelectric spectroscopy (XPS), Fourier transforms infrared spectroscopy (FTIR), transmission electron microscope (TEM) and powder X-ray diffraction (XRD). The results revealed that the fluorescence intensity of the Cs2ZnCl4 PNCs was significantly enhanced after the introduction of norfloxacin. The Cs2ZnCl4 PNCs can be used as a fluorescent probe to selectively and sensitively detect norfloxacin in the concentration range from 0.2 to 50.0 µM, with a correlation coefficient (R2) of 0.9954 and the limit of detection (LOD, 3σ) of 0.1499 µM. The preparation and application of a lead-free perovskite fluorescent probe for norfloxacin would promote the application of perovskite fluorescent probes in biochemical assays.

Knockdown of CkrL by shRNA deteriorates hypoxia/reoxygenation-induced H9C2 cardiomyocyte apoptosis and survival inhibition Via Bax and downregulation of P-Erk1/2.

Integrin ß1 subunit and its downstream molecule integrin-linked kinase and focal adhesion kinase have been confirmed to be essential to cell survival and inhibition of apoptosis and hypoxia/reoxygenation (H/R)-induced injuries in cardiomyocytes. However, it is still unclear whether CrkL [v-crk avian sarcoma virus CT-10 oncogene homolog (Crk)-like], which acts also as a component of the integrin pathway, could also affect H/R-induced injuries in the cardiomyocytes. The rat-derived H9C2 cardiomyocytes were infected with a CrkL small hairpin RNA interference recombinant lentivirus, which knockdowns the endogenous CrkL expression in the cardiomyocytes. Apoptosis, cell proliferation and survival were examined in the H9C2 cardiomyocytes treated with either H/R or not. Results showed that knockdown of CrkL could significantly increase apoptosis and inhibition of the cell proliferation and survival and deteriorate the previously mentioned injuries induced by H/R. In contrast, overexpression of human CrkL could relieve the exacerbation of the previously mentioned injuries induced by CrkL knockdown in the H9C2 cardiomyocytes via regulation of Bax and extracellular signal-regulated kinase1/2 (p-ERK1/2). In conclusion, these results confirmed that knockdown of CrkL could deteriorate H/R-induced apoptosis and cell survival inhibition in rat-derived H9C2 cardiomyocytes via Bax and downregulation of p-ERK1/2. It implies that CrkL could mitigate H/R-induced injuries in the cardiomyocytes.

[Study on relationship between alfalfa canopy spectral reflectance and leaf water content].

In the present study, alfalfa canopy reflectance was researched at alfalfa squaring period under different irrigation amount at the hutubi county grassland ecological station. Determining the spectral diagnostic model of alfalfa leaf moisture content was determined by spectrometry. The results showed that (1) The spectral reflectance of alfalfa canopy gradually decreases with the increase in the leaf water content in the near infrared. (2) The spectral inversion model of alfalfa leaf moisture content established by normalized reflectance spectra is superior to the original reflectance spectra, and the prediction model established in the 1,344-1,660 nm band has the lowest average relative error (7.8%). (3) In this study, the spectral diagnostic model of the leaf moisture content is: Y=0.962 - 7.560X1451 + 5.295X1473. The spectral prediction model of the alfalfa leaf moisture content can provide a basis for decision making for scientific irrigation of alfalfa.

[Measuring soil water content by using near infrared spectral characteristics of soil].

Different textured soils (sandy loam, silty clay loam and clay) from Manas County, Xinjiang were researched with indoor spectral reflectance, continuum removal was used to process soil spectra curve, and correlation analysis was made about normalized spectral reflectance and water content for modeling. The results show that different textured soils have reflectance in a order that clay>silty clay loam>sandy loam; the critical points of field capacity in sandy loam, silty clay loam and clay were 20.01%, 24.10% and 30.43% respectively, and water content was inversely proportional to spectral reflectance below such critical points while proportional above the points. Within 1390-1623 nm band, the negative correlation coefficients of soil water content and normalized spectra reflectance show better negative correlation and reaching significant levels, R2 of the model established for soil water content prediction exceeded mostly 0.8, and the average relative error of the model was 10%. The model could accurately reflect the soil moisture content, Its advantages such as accuracy, non-destruction and rapidness provide a new approach to measuring soil water content.