Microfluidic fluorescent platform for rapid and visual detection of veterinary drugs.

The overuse of veterinary drugs and veterinary drug residues is increasingly becoming an obstacle to sustainable development worldwide. It is therefore imperative to establish a quantitative, sensitive and efficient method for the detection of veterinary drugs. Herein, we developed a visual microfluidic detection platform for rapid and sensitive detection of veterinary drugs using CdTe quantum dots (QDs) with three different ligands as the sensing units. Green-emissive 3-mercaptopropionic acid (MPA)-CdTe QDs, yellow-emissive thioglycolic acid (TGA)-CdTe QDs and orange-emissive N-acetyl-l-cysteine (NAC)-CdTe QDs were synthesized by a sulfhydryl aqueous phase method. These CdTe QDs show selective rapid fluorescence response to pefloxacin (PEF), malachite green (MG), and 1-aminohydantoin hydrochloride (AHD). With the concentration of veterinary drugs increasing, the CdTe QDs reveals a fluorescence color variation from bright to dark until quenched and the response degree of CdTe QDs with different ligands to veterinary drugs is different. Specifically, the limits of detection (LODs) of MPA-CdTe, TGA-CdTe and NAC-CdTe QDs probes for PEF were 7.57 µM, 1.75 µM and 2.90 µM, respectively, and the response was complete in a few seconds, realizing the sensitive and rapid detection of PEF. The three kinds of CdTe QDs could also be used in the detection of other veterinary drugs such as MG and AHD. Finally, a microfluidic detection platform was constructed for visual sensing and rapid detection towards veterinary drugs. The sensor platform holds the advantages of simple operation, low cost, rapid sensing and good sensitivity, and is potentially useful for visual quantitative detection of veterinary drug residues in aquatic products and the environment.

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins.

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins have been developed to afford chiral dispiro[indene-pyrrolidine-pyrimidine]s. Through this strategy, the target products could be obtained in good to excellent yields with excellent stereoselectivities. In addition, the synthetic utility was verified through a gram-scale synthesis, one-pot three-component reactions and further transformation experiments of the products.

[Application of individualized controllable stress external fixation in open tibial fractures].

OBJECTIVE: To study the clinical effect of individualized controllable stress external fixator in the treatment of open tibial fractures. METHODS: From December 2018 to July 2020, 60 patients with open tibial fractures were treated, including 35 males and 25 females;The age ranged from 23 to 58 years;The course of disease was 1.2 to 10.0 h. According to the stress stimulation on the fracture end after operation, all patients were divided into 4 groups, including non stress group (15 cases) and 3 groups with different stress stimulation(15 cases in each group). All patients with open tibial fractures were treated with controllable stress external fixator. Four weeks after operation, the stress group adjusted the elastic external fixator to apply axial stress of 1/6, 2/6 and 3/6 of their own weight to the fracture end based on the patient's weight. The wound healing of all patients after operation was observed, the plain CT images of fracture ends at 4, 6, 8, 10 and 12 weeks after operation were followed up, the average valueof callus area per 10 scanning planes was calculated, and the differences between the groups were compared. The fracture healing was observed and statistically analyzed. RESULTS: The wounds of all patients healed well, of which 7 patients underwent secondary free skin grafting and transferred myocutaneous flap. All patients were followed up for 12 to 24 months, with an average of 16.5 months. The final follow-up results showed that the fracture healing of stress groups and non stress group had significant difference(P<0.05). After axial stress stimulation at the fracture end, CT examination was performed on the fracture end of all patients at 4, 6, 8, 10 and 12 weeks. The average values of callus area in 10 plain scanning planes were calculated as follows:no stress group (0.275±0.092) mm2, (0.383±0.051) mm2, (0.412±0.048) mm2, (0.472± 0.019) mm2, (0.548±0.036) mm2, the area of callus growth in the stress group was significantly higher than that in the non stress group. There was significant difference among these groups(P<0.05). CONCLUSION: When the controllable stress external fixation technique is used to treat open tibial fractures, the elastic external fixator is adjusted according to the patient's own weight after 4 weeks, and a certain axial stress is applied to the fracture end, which is conducive to the fracture healing of patients, and can reduce the incidence of delayed union or nonunion of open fractures, which has a certain application value.

Auxin acts as a downstream signaling molecule involved in hydrogen sulfide-induced chilling tolerance in cucumber.

MAIN CONCLUSION: This report proves a cross talk between H2S and IAA in cold stress response, which has presented strong evidence that IAA acts as a downstream signal mediating the H2S-induced stress tolerance in cucumber seedlings. We evaluated changes in endogenous hydrogen sulfide (H2S) and indole-3-acetic acid (IAA) emission systems, and the interactive effect of exogenous H2S and IAA on chilling tolerance in cucumber seedlings. The results showed that chilling stress increased the activity and relative mRNA expression of L-/D-cysteine desulfhydrase (L-/D-CD), which in turn induced the accumulation of endogenous H2S. Similarly, the endogenous IAA system was triggered by chilling stress. We found that 1.0 mM sodium hydrosulfide (NaHS, an H2S donor) significantly enhanced the activity of flavin monooxygenase (FMO) and relative expression of FMO-like proteins (YUCCA2), which in turn elevated endogenous IAA levels in cucumber seedlings. However, IAA had little effects on activities of L-/D-CD and endogenous H2S levels. H2S-induced IAA production accompanied by increase in chilling tolerance, as shown by the decrease in stress-induced electrolyte leakage (EL) and reactive oxygen species (ROS) accumulation, and increase in gene expressions and enzyme activities of photosynthesis. 1-naphthylphthalamic acid (NPA, an IAA polar transport inhibitor) declined H2S-induced chilling tolerance and defense genes' expression. However, scavenging of H2S had a little effect on IAA-induced chilling tolerance. These results suggest that IAA acting as a downstream signaling molecule is involved in the H2S-induced chilling tolerance in cucumber seedlings.

Steganographic coding scheme based on dither convolutional trellis under resampling mechanism.

With the rapid development of mobile internet and cloud computing, numerous digital me-dia files in mobile social networking and media sharing software have become the important carriers of steganography. However, these digital media files may be resampled by the media server when being pushed to the intelligent mobile terminals. The resampling of digital media files is a transfor-mation which enlarges or shrinks objects by a scale factor that is the same in all dimensions. In order to reduce embedding distortion while ensuring the correct extraction of secret messages under resam-pling mechanism, a steganographic coding scheme based on dither convolutional trellis is proposed in this paper. The resampling mapping is estimated with finite sample pairs. The resampling stego media files with secret messages embedded are generated from the estimated resampling cover media files by syndrome-trellis codes (STCs). According to the estimated resampling mapping, the dither convolutional trellis for one dimensional resampling is constructed to generate the source stego me-dia files from source cover media files and resampling stego media files. The steganographic coding scheme is also extended to the circumstance of two dimensional resampling such as image scaling. The experimental results show that the proposed steganographic scheme can achieve less embedding dis-tortion while ensuring the accuracy of secret messages extraction under multi-dimensional resampling mechanism.