[Screening of place cell and analysis of its influencing factors for pigeons].

Place cell with location tuning characteristics play an important role in brain spatial cognition and navigation, but there is relatively little research on place cell screening and its influencing factors. Taking pigeons as model animals, the screening process of pigeon place cell was given by using the spike signal in pigeon hippocampus under free activity. The effects of grid number and filter kernel size on the place field of place cells during the screening process were analyzed. The results from the real and simulation data showed that the proposed place cell screening method presented in this study could effectively screen out place cell, and the research found that the size of place field was basically inversely proportional to the number of grids divided, and was basically proportional to the size of Gaussian filter kernel in the overall trend. This result will not only help to determine the appropriate parameters in the place cell screening process, but also promote the research on the neural mechanism of spatial cognition and navigation of birds such as pigeons.

MoO3 Nanorods Decorated by PbMoO4 Nanoparticles for Enhanced Trimethylamine Sensing Performances at Low Working Temperature.

The gas sensing performance of metal oxides is limited by the lack of conductivity and sensing activity. Inducing the release of more electrons and activating more chemisorbed oxygen ions to participate in the gas sensing reaction can effectively overcome this limitation. The development of a PbMoO4/MoO3 heterostructure prepared by the addition of Pb2+ ions with MoO3 nanorods is reported for highly sensitive and selective trimethylamine (TMA) detection. The response of the PbMoO4/MoO3 sensor (33.2) to 10 ppm TMA is improved 3-fold compared to the MoO3 sensor (10.7), and the working temperature is reduced from 170 to 133 °C. The enhanced gas sensing performance and mechanism of PbMoO4/MoO3 were demonstrated using the energy band diagram and X-ray photoelectron spectroscopy (XPS) analysis. It is mainly attributed to the following promotion: (1) the induction of Pb2+ ions increases the electron density around the Mo element, enabling the decorated MoO3 to release electrons easily; (2) the formed PbMoO4/MoO3 heterojunction endows a high degree of electron transfer at the interface; (3) the formation of the potential barrier causes the device resistance to decrease significantly upon TMA exposure. Finally, the practicability of the sensor was verified by detecting TMA released from Carassius auratus and shrimp to reflect their freshness.

Au-Fe3O4 heterodimer multifunctional nanoparticles-based platform for ultrasensitive naked-eye detection of Salmonella typhimurium.

In this work, we developed an ultrasensitive colorimetry for Salmonella typhimurium detection with multifunctional Au-Fe3O4 dumbbell-like nanoparticles (DBNPs) which possessed easy bio-modifiability, excellent LSPR characteristics, superparamagnetic properties and super peroxidase-like activity. In the detection, the anti-S. typhimurium antibody modified DBNPs (IDBNPs) bound with S. typhimurium and aggregated on their surfaces in a large number, which showed much quicker magnetic response than free IDBNPs. By controlling appropriate separation conditions, IDBNPs@S. typhimurium composites were captured, while free IDBNPs were remained in the supernatant. Therefore, by detecting the absorbance of the supernatant, quantitative detection was achieved from 10 to 1000 CFU/mL. Moreover, utilizing the peroxidase-like activity of IDBNPs, we further realized semi-quantitative naked-eye detection. By adding ABTS into the above supernatant, which was oxidized to green chelate (OxABTS), colorimetric signal was amplified significantly, and meanwhile, the green chelates and the wine-red IDBNPs engendered mixed color, enhancing the range of color gradation and greatly improving the visual resolution. Finally, a detection limit (10 CFU/mL) comparable with that of above spectrum measurement was achieved. Besides, our method exhibited efficient capture capability (nearly 100% even for rare S. typhimurium), and had good stability and specificity, and acceptable anti-interference ability in fetal bovine serum and milk samples.

The quality of life in Chinese juvenile idiopathic arthritis patients: psychometric properties of the pediatric quality of life inventor generic core scales and rheumatology module.

BACKGROUND: Juvenile idiopathic arthritis (JIA) may seriously affects patients' quality of life (QoL), but it was rarely focused and studied in China, so we explore JIA children's QoL using Chinese version of the PedsQL4.0 Generic Core and PedsQL3.0 Rheumatology Module scale, and analyzed the psychometric properties of these two Scales among Chinese JIA children. METHODS: We recruited 180 JIA patients from Children's Hospital Affiliated to Capital Institute of Pediatrics and Hebei Yanda Hospital from July 2018 to August 2019. The questionnaires include information related on JIA, PedsQL4.0 generic core and PedsQL3.0 Rheumatology Module scales. According to the disease type, onset age of and course of JIA, we divided them into different groups, then compared the QoL status among different groups. Moreover, we analyzed the reliability and validity of these two scales in these 180 JIA children. RESULTS: The mean score of PedsQL4.0 generic core scale on these 180 patients was 82.85 ± 14.82, for these in active period was 72.05 ± 15.29, in remission period was 89.77 ± 9.23; the QoL score of systemic, polyarticular and oligoarticular JIA patients were 77.05 ± 19.11, 84.33 ± 12.46 and 87.12 ± 10.23. The mean score of PedsQL3.0 Rheumatology Module scale on 180 patients was 91.22 ± 9.45, for these in active period was 84.70 ± 11.37, in remission period was 95.43 ± 4.48; the QoL score of systemic, polyarticular and oligoarticular JIA patients were 89.41 ± 11.54, 89.38 ± 10.08 and 93.71 ± 6.92. In the PedsQL 4.0 Generic Core scale, the α coefficients of total scale and almost every dimension are all greater than 0.8 except for the school activity dimension of 0.589; the correlation coefficients of 22 items' scores (total 23 items) with the scores of dimensions they belong to are greater than 0.5 (maximum value is 0.864), and the other one is 0.406. In PedsQL3.0 Rheumatology Module scale, except for the treatment and worry dimensions of 0.652 and 0.635, the α coefficients of other dimensions and the total scale are all greater than 0.7; the correlation coefficients of all items' score were greater than 0.5 (the maximum is 0.933, the minimum is 0.515). CONCLUSIONS: The QoL of Chinese JIA children is worse than their healthy peers, these in active period and diagnosed as systemic type were undergoing worst quality of life. The reliability and validity of PedsQL 4.0 Generic Core and PedsQL3.0 Rheumatology Module scale in Chinese JIA children are satisfactory, and can be used in clinical and scientific researches.

A pH tuning single fluorescent probe based on naphthalene for dual-analytes (Mg2+ and Al3+) and its application in cell imaging.

In this study, a naphthalene Schiff-base P which serves as a dual-analyte probe for the quantitative detection of Al3+ and Mg2+ has been designed. The proposed probe showed an ''off-on'' fluorescent response toward Al3+ in ethanol-water solution (1 : 9, v/v, pH 6.3, 20 mM HEPES) over other metal ions and anions, while the detection by the probe could be switched to Mg2+ by regulating the pH from 6.3 to 9.4. The sensing mechanisms of P to Al3+/Mg2+ are attributed to inhibition of the photo-induced electron transfer (PET) process by the formation of 1 : 1 ligand-metal complexes. More importantly, the probe was applied successfully in living cells for the fluorescent cell-imaging of Al3+ and Mg2+.

[Determination of deltamethrin and its toxicity biomarkers in rabbit urine by high performance liquid chromatography-tandem mass spectrometry].

A method was developed for the determination of biomarkers related to toxicity of deltamethrin in rabbit urine by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The target analytes in this method are as follows:deltamethrin and its two metabolites (1R-cis)-3-(2,2-dibromoethenyl)-2,2-dimethylcyclopropane carboxylic acid (dibromochrysanthemic acid) and 3-phenoxybenzoic acid (3-PBA), and five toxic biomarkers, viz. serotonin hydrochloride (5-HT), 5-hydroxyindole-3-acetic acid (5-HIAA), 3-nitropropionic acid (3-NPA), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and 6-methoxyguanine. Urine samples were cleaned by matrix solid-phase dispersion extraction (MSPD) with diatomite; and protein was precipitated with trichloroacetic acid; and then the sample solutions were purified with hydrophilic-lipophilic balance (HLB) solid-phase extraction cartridges. The biomarkers were analyzed with electrospray ionization (ESI) in a positive and negative switching scan mode, in which the positive scan mode was used for deltamethrin, 5-HT, 5-HIAA, 8-OHdG, and 6-methoxyguanine, and the negative scan mode was used for (1R-cis)-3-(2,2-dibromoethenyl)-2,2-dimethylcyclopropane, 3-PBA, and 3-NPA. The target compounds were quantified with the external standard using matrix calibration curves. The linear regression curves of the eight target compounds were linear with correlation coefficients no less than 0.9914. The LOD and LOQ of 5-HIAA were 20 µg/L and 50 µg/L, respectively, and the LODs and LOQs of the other analytes were 0.2-5.0 µg/L and 0.5-10 µg/L, respectively. The average recoveries of the analytes spiked in rabbit urine ranged from 74.2% to 98.7% at three levels, with relative standard deviations (RSDs) no more than 12%. The method was simple, fast, accurate, sensitive, and suitable for the detection for the exposure evaluation of deltamethrin.

Residue behaviors and dietary risk assessment of dinotefuran and its metabolites in Oryza sativa by a new HPLC-MS/MS method.

In this study, we developed a new method to detect dinotefuran and its metabolites (UF and DN) in Oryza sativa (Rice) by HPLC-MS/MS in multiple reaction monitoring (MRM) modes. The recovery rates for dinotefuran, UF and DN were 82.3-85.8%, 83.7-89.0%, and 81.6-90.2%, respectively. The dissipation kinetics of dinotefuran in rice followed a combined first+first kinetic model, where the half-lives of dinotefuran and its metabolites were determined to be between 0.5 and 2.3days. The dinotefuran residue in brown rice sampled at day 7, 14, and 21 after the last application was 0.4131mg/kg with a very low risk quotient (RQ) value. We recommend that the safety interval of application for rice is 7days. The method developed in this study is simple and rapid, with high accuracy and precision which meet the requirements for quantitative analysis of dinotefuran in rice.

Serum Bactericidal Assay: New Role in Salmonella Detection.

While inspecting animal feed for Salmonella contamination, we routinely observed bacterial colonies on selective agars that were similar in appearance to those formed by Salmonella. These were identified as Citrobacter freundii, Proteus mirabilis, and Serratia fonticola using biochemical and serological techniques. Because the presence of these bacterial species confounds identification of Salmonella, we refer to them as "interference bacteria." Polyvalent antisera against these interference bacteria were prepared by immunizing rabbits with a mixture of all three organisms. To minimize or eliminate interference by these bacteria, the polyvalent antisera were introduced between the steps of selective enrichment and Salmonella-selective plating. The antisera raised against the interference bacteria, when combined with neonatal rabbit complement, exhibited specific bactericidal activity against C. freundii, P. mirabilis, and S. fonticola. The respective serum bactericidal assay titers were 2(9), 2(8), and 2(10). In selective broth, polyvalent antisera could also kill the target bacterial cells effectively. We tested 526 samples (186 white fishmeal, 97 red fishmeal, and 243 cattle bone powder) using the polyvalent antisera and found that the rates of contamination of each species of the three respective foods decreased by 58.8, 100, and 83%. Our data indicates that polyvalent sera against C. freundii, P. mirabilis, and S. fonticola can be used as inhibitors to increase the accuracy of Salmonella detection.

[Determination of inabenfide residue in food by high performance liquid chromatography-tandem mass spectrometry].

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/ MS) method was established for the determination of inabenfide in fruits, vegetables, tea, honey, cereals and animal-derived foods. The food samples were extracted with acetonitrile, then purified by dispersion solid phase extraction using primary secondary amine (PSA) and C18 as solid phase. The residue was determined and confirmed by HPLC-MS/MS and quantified by external standard method. The mass spectrometric detection was operated with electrospray in positive ionization mode and inabenfide was identified in multiple reaction monitoring (MRM) mode. The interference of matrix was reduced by the matrix-matched calibration standard curves. The linear range of the method was 1 - 100 microg/kg, with the correlation coefficients (r2) of 0.998 - 0.999. The recoveries of inabenfide spiked in food samples were 85.2% - 112.4% at the spiked levels of 5, 10, 50 microg/kg. The relative standard deviations (RSDs) were less than 8.5%. The limits of detection (LODs) were 0.08 - 1.64 microg/kg, and the limits of quantification (LOQs) were 0.30 - 5.48 microg/kg. The results showed that the proposed method is sensitive and accurate for the determination of inabenfide in foodstuffs.

[Determination of 193 pesticide residues in vegetables and fruits by gas chromatography-mass spectrometry].

On the basis of optimization of solid phase extraction adsorbent, eluting solvent types and amounts, a gas chromatography-mass spectrometric method was developed for the determination of 193 pesticide residues in vegetables and fruits. The analytes were extracted from the samples using acetonitrile. The extract was cleaned-up with a C18/PSA solid-phase extractor, eluted by acetonitrile and analyzed by GC-MS under selected ion monitoring (SIM) mode using triphenyl phosphate (TPP) as internal standard. The linear range was from 10 to 1 000 microg/L for 130 pesticides, from 20 to 1 000 microg/L for 34 pesticides, from 50 to 1 000 microg/L for 26 pesticides, from 100 to 1 000 microg/L for the other 3 pesticides with the good correlation coefficients (r > or = 0.996 7). The limits of detection were 0.04 - 8.26 microg/kg. The mean recoveries of the pesticides were 71.6% -117.9%. The relative standard deviations were 3.0% - 11.8%. This method is simple, rapid, sensitive and specific. It is appropriate for the simultaneous identification and quantification of the multi-residues in fruits and vegetables.