Determination of Lincomycin in Milk Using Cu-Based Metal-Organic Framework Adsorbent and Liquid Chromatography-Tandem Mass Spectrometry.

Antibiotic drug residues can adversely affect the human body. Lincomycin is a common veterinary drug that can form residues in foods of animal origin. However, the detection of trace residue levels of lincomycin residues in real samples is challenging. Here, a simple solid phase extraction (SPE) method was developed for the enrichment of lincomycin from cow milk samples before its detection by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The adsorbent used in the SPE was a Cu-based metal-organic framework (Cu-MOF) prepared by the solvothermal synthesis approach. The prepared MOFs were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), differential thermogravimetric analysis (TG-DTA), and N2 adsorption-desorption experiments. The adsorption capacity (adsorption equilibrium, extraction time, pH), and elution solvent parameters were investigated. Under the optimized conditions of the HPLC-MS/MS method, lincomycin was detected in the linear range of 10-200 g/L with a detection limit of 0.013 ng/mL. Commercial milk samples were spiked with lincomycin, and a recovery rate between 92.3% and 97.2% was achieved. Therefore, the current method can be successfully applied for the enrichment and determination of lincomycin from milk samples.

Optimization of fermentation conditions for fermented green jujube wine and its quality analysis during winemaking.

The objective was to study the optimization of fermentation conditions for fermented green jujube wine and quality analysis. This study investigated the fermentation process conditions, the changes in physicochemical indexes, antioxidant capacity and volatile compounds measured from green jujube wine during winemaking. The optimized conditions (the initial sugar, yeast addition, fermentation time and SO2 treatments) for green jujube wine were 24%, 0.3%, 8 d, 80 mg/L, respectively. The results showed that the variation trend of different substances in green jujube wine in different fermentation periods were different. In the process of alcohol fermentation, the green jujube wine had a high 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging ability, 2,2'-amino-di (2-ethyl-benzothiazoline sulphonic acid-6) ammonium salt (ABTS) free radical scavenging ability and reducing power. Furthermore, a total of 50 volatile compounds were identified in green jujube wine, in which the relative content of aldehydes, ketones, heterocyclic and aromatic compounds were significantly reduced after fermentation.

Graphene oxide enters the rice roots and disturbs the endophytic bacterial communities.

The environmental release of graphene oxide (GO) will certainly induce the GO exposure to plants. To date, the influence of GO on the intracellular structures and the endophytic bacterial ecology of plants have been rarely reported. In the present study, the rice seedlings were exposed to GO (5 mg/L) under hydroponic condition for fifteen days with periodic stir. The cellular structures damage, GO deposition and oxidative stress were found in rice root after GO exposure. A Illumina analysis based on the bacterial 16 S rRNA gene showed that the richness, evenness and diversity of endophytic bacterial communities of rice root decreased due to GO exposure. The relative abundance of beneficial endophytic bacterial populations decreased after GO exposure. Out of potential phenotypes predicted by BugBase, the relative abundance of Gram negative, stress-tolerant and biofilm-forming phenotypes, presented an increase trend after GO exposure.

PLATOON: Premature Loss of bAby Teeth and its impact On Orthodontic Need - protocol.

OBJECTIVE: To investigate the impact of premature extraction of primary teeth (PEPT) on orthodontic treatment need in a cohort of children participating in the Born in Bradford (BiB) longitudinal birth cohort. DESIGN: Observational, cross-sectional cohort. PARTICIPANTS: We aim to recruit 1000 children aged 7-11 years: 500 with a history of PEPT and 500 matched non-PEPT controls. METHODS: After informed consent/assent, orthodontic records will be collected, including extra and intra-oral photographs and alginate impressions for study models. Participants will also complete a measure of oral health-related quality of life (COHIP-SF 19). The records will be used to quantify space loss, identify other occlusal anomalies and assess orthodontic treatment need using the Index of Orthodontic Treatment Need. For each outcome, summary statistics will be calculated and the data for children with and without PEPT compared. The records of the children identified to be in need of orthodontic treatment will be examined by an expert orthodontic panel to judge if this treatment should be undertaken at the time of the records or delayed until the early permanent dentition. Collecting robust records in the mixed dentition provides the clinical basis to link each stage of the causal chain and enable the impact of PEPT on orthodontic need to be characterised. This study is the first to provide the foundations for future longitudinal data collection allowing the long-term impact of PEPT to be studied.

Self-assembled copper nanoclusters used to mimic peroxidase for glucose detection.

A sensing system for glucose was established based on a self-assembled copper nanoclusters (Cu NCs)-based nano-enzyme and glucose oxidase (GOD). The assembled copper nanosheets (Cu NSs) were prepared in a one-step method using 2,3,4,5,6-pentafluorothiophenol (PFTP) as a reducing agent and protecting ligand. Cu NSs could be used to mimic the enzyme horseradish peroxidase. Cu NSs were endowed with excellent enzymatic catalytic activity in the oxidation of o-phenyldiamine (OPD) in the presence of H2O2. The latter could be generated in the aerobic oxidation of glucose catalyzed by GOD. Therefore, a detection method for glucose was constructed based on a Cu NSs-OPD-GOD catalytic system. This proposed sensing platform showed a standard linear range from 10 µM to 5 mM towards glucose, and the limit of detection was 5.5 µM. Finally, practical application of a sensor based on the Cu NSs nano-enzyme was verified in three sugared beverages as real samples. Our data reveal that the prepared Cu NSs could mimic peroxidase and be applied to a mixed catalytic system with GOD for glucose detection.

[Rapid nondestructive detection of apple quality attributes using hyperspectral scattering images].

The research discussed the prediction method of apple's internal quality such as firmness and soluble solids content with the combination of parameters getting from hyperspectral fitting scattering curve. The research compared different molding methods using the combination of the three Lorentzian fitting parameters with partial least squares (PLS), stepwise multiple linear regression (SMLR) and neural network (NN). The normalized combination parameters and original combination parameters were used to establish prediction models, respectively. The partial least squares (PLS) prediction models using the combination of three original parameters gave a better results with the correlation of calibration Rc = 0.93, the standard error of calibration SEC = 0.56, the correlation of validation R = 0.84, and the standard error of validation SEV = 0.94 for firmness of apples. The partial least squares (PLS) prediction models using combination of normalized parameters also gave a good results with Rc = 0.95, and the standard error of calibration SEC= 0. 29, the correlation of validation Rv = 0. 83, and the standard error of validation SEV = 0.63 for soluble solids content of apples. The research showed that using hyperspectral scattering curve can detect apple quality attributes at the same time.

[A rapid nondestructive measurement method for assessing the total plate count on chilled pork surface].

The present paper proposed a method based on the hyperspectral technology for rapidly, nondestructively quantify the total plate count on chilled pork surface. In the research, 50 chilled pork samples stored at 4 degrees C for 1-14 days were used to study the relationship between the total plate count on chilled pork surface and their hyperspectral images collected in 400-1 100 nm. Two models were established using MLR and PLSR methods, and the prediction showed that they can both give satisfactory results with R(v) = 0.886 and 0.863 respectively. The overall research demonstrates that the hyperspectral technology can well quantify the total plate count on chilled pork surface, and so indicates that it is a valid tool to assess the quality and safety properties of chilled pork in the future.

[Measurement of chlorophyll content in wheat leaves using hyperspectral scanning].

The objective of the present research was to evaluate the potential of hyperspectral scanning as a way for nondestructive measurement of chlorophyll content in wheat leaves, which can indicates the plant healthy status. One hundred twenty samples were randomly picked from Xiao Tangshan farm. Ninety samples were used as calibration set and others were used for verification set. After capturing hyperspectral image in the range of 400-1,000 nm, the chlorophyll contents of samples were measured immediately. Four different mathematical treatments were used in spectra processing in the wavelength range of 491-887 nm: multiplicative scatter correction (MSC), first derivative correction, and second derivative correction. Statistical models were developed using partial least square regression (PLSR), and stepwise multiple linear regression (SMLR) analysis technique. The results showed that the best calibration model was obtained by PLSR analysis, after processing spectra with MSC and second derivate, with a relatively higher coefficient of determination of calibration (0.82) and validation (0.79) respectively, a relatively lower RMSEC value (0.69), and a small difference between RMSEC (0.69) and RMSEP (0.71). The results indicate that it is feasible to use hyperspectral scanning technique for nondestructive measurement of chlorophyll content in wheat leaves.

[Study of spatially resolved hyperspectral scattering images for assessing beef quality characteristics].

Hyperspectral scattering techniques were used to predict beef pH, tenderness (i. e. WBSF: Warner-Bratzler Shear Force) and color parameters. Thirty-three fresh strip loin cuts were collected from 2-day postmortem carcass. After capturing scattering images and measuring pH values, the samples were vacuum packaged and aged to seventh day, then their color parameters (L*, a*, b*) and WBSF were measured as references. The optical scattering profiles were extracted from the hyperspectral images and fitted to the Lorentzian distribution (LD) function with three parameters. LD parameters, such as the peak height, full scattering width at half maximum (FWHM) and the scattering asymptotic were calculated at individual wavelength. Stepwise regression was used to determine optimal combinations of wavelengths for each of parameters. The optimal combinations were then used to establish multi-linear regression (MLR) models to predict the beef attributes. The full cross validation method was used to examine the performance of models. The models were able to predict beef WBSF with R(CV) = 0.86, and with the SE(CV) (the standard error of cross validation) of 11.7 N, 91% classification accuracy could be obtained. Two-day pH values with R(CV) = 0.86, SE(CV) = 0.07 and color parameters (L*, a*, b*) with R(CV) of 0.92, 0.90 and 0.88, with the SE(CV) of 0.90, 1.34 and 0.41 were obtained respectively. This research provided available technique for the development of multispectral system, which could be implemented online to determine beef steaks color and tenderness.

Vegetation alleviate the negative effects of graphene oxide on benzo[a]pyrene dissipation and the associated soil bacterial community.

Graphene oxide (GO) will enter the soil environment in increasing amounts. The effects of GO on the dissipation of benzo[a]pyrene (B[a]P) from contaminated soil and their phytoremediation system have been explored in this study. B[a]P is a ubiquitous soil pollutant used as a representative indicator of polycyclic aromatic hydrocarbons. A pot experiment was performed to investigate the effects of GO or/and vegetation (Tagetes patula) on B[a]P dissipation and the associated bacterial communities in soil. The bacterial communities in soil were investigated by Illumina sequencing analysis. The presence of vegetation significantly enhanced the dissipation of B[a]P from soil. The addition of GO (100 mg/kg) significantly decreased the B[a]P dissipation. When vegetation and GO coexisted, the inhibition effects of GO on B[a]P dissipation were alleviated by vegetation. Compared with the control treatment, the presence of GO or vegetation had no significant effects on the richness and diversity of bacterial communities in B[a]P-contaminated soil. Compared with the presence of only vegetation, the richness and diversity all significantly decreased when vegetation and GO coexisted. And, vegetation had a greater influence on the bacterial community composition than GO. Vegetation alleviated the inhibition effects of GO on B[a]P dissipation and had a greater influence on the associated bacterial communities than GO. This work helps to understand the interactive effects of GO and vegetation on B[a]P dissipation and the associated bacterial communities in contaminated soil.

A quencher-free 2-aminopurine modified hairpin aptasensor for ultrasensitive detection of Ochratoxin A.

A sensitive, efficient and quencher-free fluorescence aptasensor to detect Ochratoxin A (OTA) based on aptamer, 2-aminopurine (2AP) labeled Oligonucleotide sequence, as well as exonuclease I (Exo I) activity was developed. In which the aptamer specific to OTA was modified into a hairpin structure, and 8 bases at the 3' ends are exposed (H); also, 2AP is embedded in the oligonucleotide complementary to the 8 bases (2AP-probe).The detection principle based on 2AP-probe could be bonded to its complementary sequence and quenches the fluorescence of 2AP; The aptamer has a stronger affinity for the target than its complementary sequence; Exo I can dissociate single-stranded DNA and has little effect on double-stranded DNA as well as folded DNA. In the absence of OTA, the fluorescence of 2AP is quenched due to the complementary pairing of H and 2AP-probe; in the presence of OTA, H selective binding target is detached from 2AP-probe, and the fluorescence of 2AP is slightly restored. Moreover, when the Exo I is added to the detection system, 2AP-probe is dissociated by the Exo I to release the free 2AP, and the fluorescence of the system is further enhanced thereby realizing the detection of OTA. The detection limit of the aptasensor was low as 0.03 nM with a linear range of 0.5-100 nM. Moreover, the aptasensor has good selectivity and practicability and also has good potential in realizing the detection of toxic and harmful substances in food complex matrices.