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It's of great value to study on splitting tensile properties of rock after freeze-thaw cycles of rock mass in cold regions. The typical red sandstone in cold region was selected for testing, the freeze-thaw (F-T) cycle experiments with different numbers (0, 5, 10, 15, and 20 times) were performed on red sandstone specimens, and the effects of F-T cycle number on the P-wave velocity, dry density, and porosity of red sandstone were studied in detail. In addition, both the static and dynamic mechanical properties of red sandstone specimens after different F-T cycles were tested by using rock testing machine and ø50 mm split Hopkinson bar system, and the influence of F-T cycle number on the static and dynamic strength, deformation, and failure mode of red sandstone was systematically analyzed. F-T damage degree of red sandstone was defined based on the variation in P-wave velocity. Results show that with the increase of F-T number, the internal cracks of red sandstone continuously expand, bonding between mineral particles gradually decreases. Both the P-wave velocity and dry density of specimens gradually decrease, while the porosity and damage degree gradually increase. The static and dynamic splitting tensile strengths of red sandstone specimens gradually decrease with the increase of F-T number, while the time needed to reach the peak stress gradually increases. After 20 F-T cycles, the static and dynamic splitting strengths of red sandstone specimens decreased by 41.88% and 21.93%, respectively. Under the same F-T cycle number, the dynamic splitting strength of red sandstone specimens is increased by 2～3.5 times compared to the specimen under static loading. Under the static splitting condition, the red sandstone specimen exhibits the central splitting failure mode. However, an obvious crushed region at both ends of specimens was observed under dynamic loading. Additionally, with the increase of F-T number, the crushed area increases gradually, while the size of fragments gradually decreases. The damage degree of red sandstone increases logarithmically with the increase of F-T number.

Radiation-related teeth damage is a common complication in nasopharyngeal carcinoma (NPC) patients undergoing radiotherapy (RT) that seriously affects their oral health-related quality of life (OHRQoL). However, few studies have focused on protecting teeth function. This study aimed to calculate dental dose limits based on OHRQoL. Analysis was performed on 96 NPC patients who received RT (all received routine pre-radiotherapy dental interventions in our department). Based on the General Oral Health Assessment Index (GOHAI), OHRQoL was assigned into poor (

In this study, we established a method for the determination of metronidazolem, dimetridazole and ronidazole in honey by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The analytes were extracted from samples, purified using a cation exchange cartridge, separated on a C18 (3.0 mm × 100 mm, 1.7 μm) chromatographic column, detected in the multiple reaction monitoring (MRM) mode, and quantitated by an internal standard method. Metronidazolem, dimetridazole and ronidazole were separated well and their calibration curves were linear in the concentration range of 1.0–100.0 ng/mL. The relative standard deviation for replicate determinations was 1.6%–3.7% (n = 6), and the average recoveries for spiked samples ranged from 95.0% to 101.4%. This method has the advantages of low matrix interference, simple operation and high accuracy, an is suitable for the determination of the residues of metronidazolem, dimetridazole and ronidazole in honey.

Underground coal mining will cause violent deformation of the ground surface, forming a large area of subsidence area, building on coal mining subsidence area will have great safety risks, mastering the relevant laws of the deformation of the ground surface of the buildings and is the prerequisite to ensure the safety of the construction on the mining (movable) hollow area in the subsidence area. Taking the buildings in coal mining subsidence area as the research object, the means of combining 3D printing technology and similar material simulation are used, firstly, the printing materials and similar materials are screened, and the experimental model for researching the mechanism of building-foundation coupling is established, and through the experiments, the corresponding rules of the buildings and the deformation of the ground surface are summarized. Results show that: different types of buildings are affected by surface deformation differently, large buildings are more likely to be affected by quarrying, and large buildings are more likely to be affected by tilting deformation due to their stronger structural integrity.

Cancer poses a serious threat to human health and is the most common cause of human death. Polymer-based nanomedicines are presently used to enhance the treatment effectiveness and decrease the systemic toxicity of chemotherapeutic agents. However, the disadvantage of currently polymeric carriers is without therapy procedure. Herein, for the first time, glutathione (GSH)-responsive polymer (PRES) with anti-cancer effect was synthesized following the condensation–polymerization method using resveratrol (RES) and 3,3′-dithiodipropionic acid. PRES can not only suppress the tumor cells growth but can also self-assemble into nanoparticles (∼93 nm) for delivering antitumor drugs, such as paclitaxel (PTX@PRES NPs). The system could achieve high drug loading (∼7%) and overcome multidrug resistance (MDR). The results from the in vitro studies revealed that the NPs formed of PRES were stable in the systemic circulation, while could be efficiently degraded in tumor cells high GSH environment. Results from cytotoxicity tests confirmed that PTX@PRES NPs could effectively suppress the growth of cancer cells (A549) and drug-resistant cells (A549/PTX). The NPs could also be used to significantly increase the therapeutic efficacy of the drugs in A549/PTX tumor-bearing mice. In vivo investigations also demonstrated that the PRES-based NPs exhibited tumor inhibition effects. In summary, we report that the GSH-responsive polymer synthesized by us exhibited multiple interesting functions and could be used for effective drug delivery. The polymer exhibited good therapeutic effects and could be used to overcome MDR. Thus, the synthesized system can be used to develop a new strategy for treating cancer.

The monitoring of the overflow concentration of the thickener is the key to realize intelligent dosing of coal slurry. The overflow concentration monitoring method based on the sensor will lead to the delay of flocculant regulation. In order to solve the above problem, a prediction method of overflow concentration of thickener based on improved sparrow search algorithm (ISSA) and long-short term memory (LSTM) is proposed. Firstly, the correlation analysis and pretreatment of multi-parameter time series in the process of concentration production are carried out to obtain the input variables. Secondly, the multi-strategies are combined to improve sparrow search algorithm (SSA). Tent chaotic map is introduced to initialize the sparrow population to ensure population diversity and speed up algorithm convergence. The optimization process of SSA is improved by using the spiral predation strategy to balance both local development and global search capabilities. The firefly perturbation strategy is used to perturb the sparrow search results to improve the global search performance and avoid the algorithm falling into local optimization. Thirdly, ISSA is used to optimize the hyperparameters of the two-layer LSTM network model. Finally, the overflow concentration prediction model based on ISSA-LSTM is established for on-line monitoring. The experimental results show the following points. ① The Ackley function and Rastigin function are selected as test functions. It is concluded that ISSA's global optimization capability and convergence speed are better than those of the particle swarm optimization (PSO) algorithm, whale optimization algorithm (WOA) and standard SSA. ② Among the three improved strategies, the spiral predation strategy plays a leading role in improving the performance of ISSA. The chaotic map and the firefly perturbation strategy coordinate the convergence speed and global search capability of the algorithm to further improve the optimization performance of the algorithm. ③ ISSA is used to optimize the hyperparameters of LSTM, which solves the problem of under-fitting or over-fitting when the values are determined by subjective experience. The prediction precision of overflow concentration of the ISSA-LSTM model reaches 97.26%, which is higher than that of double-layer LSTM, SSA-LSTM, and least square support vector machine (LSSVM) models. ④ Data pretreatment can improve the precision of the model, and the prediction precision of overflow concentration after noise reduction is improved by 30.25% compared with that before noise reduction.