Shandong Science

Development of marine in situ dissolved oxygen sensor based on fluorescence quenching and its quantitative calibration algorithm

YUAN Da, FENG Xian-dong, ZHANG Yun-yan, WU Bing-wei

Shandong Science. 2021, 34(2): 1-10. doi:10.3976/j.issn.1002-4026.2021.02.001

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To meet the demand of in situ accurate monitoring of seawater dissolved oxygen using a domestic sensor, an optical seawater dissolved oxygen sensor was developed using modulation-demodulation digital quadrature lock-in amplification detection technology. The developed sensor achieved accurate detection of weak fluorescence lifetime. The dissolved oxygen sensor temperature coefficient was calibrated through polynomial regression analysis. A polynomial quantitative algorithm model of the fluorescence phase, dissolved oxygen concentration, and temperature was established to achieve the accurate detection of dissolved oxygen. Under a random temperature and dissolved oxygen concentration within the calibration test temperature range, the temperature measurement accuracy of the sensor is ±0.1 ℃ and the accuracy of dissolved oxygen measurement is ±0.1 mg/L after calibration.

Design and analysis of a battery condition monitoring system for marine exploration robots

SUN Xiao-hui

Shandong Science. 2021, 34(2): 11-17. doi:10.3976/j.issn.1002-4026.2021.02.002

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Considering the poor safety and controllability of a lithium iron phosphate battery in marine exploration robots, a charge/discharge management system based on an STM32 single-chip microcomputer is proposed. The hardware and related circuits of the main control module, single-battery voltage monitoring module, and equalization module are designed. The control mode adopts a master-slave topology. Through hardware tuning and optimization, the work area of the circuit board is considerably reduced, and the cooling performance of the system is improved. Test results show that the voltage, current, and temperature data are correctly displayed; the maximum detection deviation of single-battery voltage is 0.96%; and the maximum single-battery voltage exceeds the average voltage of a battery pack by 6 mV. Thus, the balancing effect is good.

In vitro bacteriostatic test of ten Chinese herbal medicines against Salmonella pullorum

YANG Jin-bo, YU Zhong-na, LI Li, WANG Zhao, YU Lei

Shandong Science. 2021, 34(2): 18-23. doi:10.3976/j.issn.1002-4026.2021.02.003

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The agar plate-drilling method, Oxford cup method, and drug-sensitive tablet method were used to detect the in vitro bacteriostatic activities of ten Chinese herbal medicines, namely Paederia scandens, Lycii cortex, Pulsatillae radix, Isatidis folium, Taraxaci Herba, Schisandrae chinensis Fructus, Mume fructus, Folium artemisiae argyi, Coptidis rhizoma, and Salviae miltiorrhizae radix, on Salmonella pullorum. In addition, a single Chinese herbal medicine with better in vitro bacteriostatic effect was screened. The results showed that Schisandrae chinensis fructus and Mume fructus were highly sensitive to Salmonella pullorum, whereas Salviae miltiorrhizae radix and Coptidis rhizoma were generally sensitive to Salmonella pullorum. The other six Chinese herbal medicines were not sensitive to Salmonella pullorum. These results suggest that Schisandrae chinensis fructus and Mume frutus have certain antibacterial effects on Salmonella pullorum and that different Chinese herbal medicines have different antibacterial effects. This study provides a basis for the clinical treatment of Salmonella pullorum as well as for the development of Chinese herbal medicine preparations.

Analysis of the mechanism of Pseudostellariae Radix against myocardial ischemia based on network pharmacology and molecular docking

TENG Li-qing, ZHOU Tao, WANG Xiao, JIANG Wei-ke

Shandong Science. 2021, 34(2): 24-33. doi:10.3976/j.issn.1002-4026.2021.02.004

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To explore the potential mechanism of anti-myocardial ischemia of Pseudostellariae Radix, the active components and targets associated with myocardial ischemia were predicted using network pharmacology, and the key target network of anti-myocardial ischemia was constructed. GO（gene ontology) function and Pathway enrichment analysis were conducted, and molecular docking verification was performed between the active components and the key targets. Eight active components of Pseudostellariae Radix and 50 key targets of anti-myocardial ischemia were obtained. GO function and Pathway enrichment analysis showed that anti-myocardial ischemia effects of Pseudostellariae Radix were mainly involved in biological processes such as apoptosis, angiogenesis, and inflammation, including MyD88-independent TLR4 cascade (MyD88-independent TLR4 signal transduction pathway), MyD88:MAL cascade initiated on plasma membrane, and TLR4 signaling (activated TLR4 signal pathway). The main targets included JUN, MAPK1, IKBKG, PTPN11, and RELA. Molecular docking showed that dandelion terpenol had the best binding with the key targets AKT1, IL6, MAPK1 and TP53. The mechanism of anti-myocardial ischemia of Pseudostellariae Radix through multiple pathway and multiple targets was revealed in this study, which provides a basis for further study of the anti-myocardial ischemia effect of Pseudostellariae Radix.

A method for detecting the content of tamsulosin hydrochloride sustained-release tablets in Beagle dogs based on liquid chromatography-mass spectrometry

GAO Qi-zhen, LIU Fang-yu, DING Ping-tian

Shandong Science. 2021, 34(2): 34-41. doi:10.3976/j.issn.1002-4026.2021.02.005

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In this study, we developed a method based on liquid chromatography-mass spectrometry to detect content changes in animals administered commercially available tamsulosin hydrochloride sustained-release tablets. Beagle dogs were used as the experimental animals to construct drug pharmacokinetic curves as well as to verify the reliability of the method. The column used was the Zorbax Extend-C18 column (150 mm×4.6 mm, 5 μm). C18 (4.0 mm×3.0 mm) was used as the guard column, and the mobile phase was methanol-water-formic acid (V（methanol）:V(water):V(formic)=85:14:1). The flow rate was 0.6 mL/min, column temperature was 30 ℃, and injection volume was 20 μL. The ESI ion source positive ion multiple reaction monitoring mode was used to select ion pairs 409.3→228.2 and 256.3→167.1 for determination. The results showed that tamsulosin hydrochloride has a good linear correlation in the concentration range of 0.1~10.0 ng/mL. The precision was 7.1%, and the recovery rate of extraction was 92%. The content changes of tamsulosin hydrochloride sustained-release tablets in Beagle dogs were accurately described. The above method has high sensitivity, good specificity, and high precision and can quickly and easily detect the content changes in animals administered commercially available tamsulosin hydrochloride sustained-release tablets.

Analysis and synthesis of impurity source in Cefdinir

WANG Jing, WU Dan, LIU Long

Shandong Science. 2021, 34(2): 42-47. doi:10.3976/j.issn.1002-4026.2021.02.006

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To improve the quality control of Cefdinir API and establish its quality criteria, the preparation method for Cefdinir was analyzed and five related impurities (Thiazolylacetyl glycine oxime, impurity O, impurity D, impurity G, and impurity S) were synthesized and characterized by 1H NMR and Ms. The purities of related substances obtained by HPLC detection were over 99%，and can be used as impurity reference substances for the quality control of Cefdinir, which provides a basis for the industrial development and quality control of Cefdinir.

Precise positioning system for mine personnel based on ultra wide band technology

ZHAO Lin, SUN Zeng-rong, WANG Ji-qiang, LIU Tong-yu

Shandong Science. 2021, 34(2): 48-53. doi:10.3976/j.issn.1002-4026.2021.02.007

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Herein, a precise positioning system for mine personnel based on the ultra wide band (UWB) technology is proposed, and the basic principle of typical SDS-TWR algorithm is analyzed. Using mine CAD drawings and two-dimensional (2D) coordinate positioning algorithm, this is the first study to realize a comprehensive management system of real-time, dynamic, synchronous tracking and monitoring, high-precision positioning, and trajectory playback in a 2D-CAD plane. The system has been tested at the Mazhuang Iron Mine of Laiwu Mining. Experimental results show that within 200 m of the UWB signal coverage, the positioning error of the system with respect to a static target is less than 30 cm, and the positioning error of a dynamic target is less than 1.65 m with a moving speed of 25 km/h. The system meets the requirements of personnel positioning in coal mines and has a broad market potential and application values.

A combined model for forecasting shared bikes demand based on causal analysis and similar day selection

XU Chang-xing, WANG Wei-ping , CHANG Xi-ming, BAO Xu , WU Jian-jun

Shandong Science. 2021, 34(2): 54-64. doi:10.3976/j.issn.1002-4026.2021.02.008

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Short-term demand of shared bikes forecasting plays an important role in optimizing the layout of free-floating bike sharing systems and bikes rebalancing. To improve the accuracy of demand forecasting methods for the emerging shared bikes business, this study establishes a combined forecasting model based on Stacking strategy and examines the impact of temporal variables and weather factors on shared bikes demand. In particular, the Granger causality test is used to identify the key weather indicators that cause demand fluctuations. We extract the set of similar samples for each period of the day for prediction based on the grey correlation index of weather variables. The Stacking strategy is then introduced to integrate random forest, support vector regression, and other machine learning algorithms for establishing a combined forecasting model to predict the short-term demand in different regions. Finally, using free-floating bike sharing data in Beijing, the proposed combined model is tested. The prediction results of combined model demonstrate that the mean absolute percentage error decreased by 9.1% compared with the single prediction model, thus improving the accuracy of the short-term demand forecast of shared bikes and providing useful information for bike relocation.

Research progress on the effect of biomechanics on proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells

CAO Sheng-nan, SHI Bin, SUN Guo-dong, WANG Cong-an, WANG Dan-dan

Shandong Science. 2021, 34(2): 65-74. doi:10.3976/j.issn.1002-4026.2021.02.009

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The biomechanical environment of bone marrow mesenchymal stem cells (BMSCs) in vivo is relatively complex. To explore the relationship between biomechanics and the proliferation and osteogenic differentiation of BMSC, This review summarizes the current research status and latest progress of the effects of biomechanical microenvironment on the proliferation and differentiation of bone marrow mesenchymal sterm cells in recent years.Results showed that mechanical tension stress and fluid shear stress on BMSCs generated most of the stimuli to direct cell differentiation and that larger compression force and static water pressure on BMSCs generated most of the stimuli to direct cells toward cartilage differentiation and a minority of cells toward osteogenic differentiation. Cell differentiation in each direction occurred under its optimal conditions. Here we reviewed the effects of biomechanics on proliferation and osteogenic differentiation of BMSC, which may provide insights and references for research on bone tissue engineering, regenerative medicine, and clinical applications of BMSCs.

Vacuum cooling crystallization process of calcium gluconate

ZHAO Gai-ju , LIANG Xi, YUN Dong-ling , GENG Wen-guang , WANG Lu-yuan, SUN Rong-feng

Shandong Science. 2021, 34(2): 75-80. doi:10.3976/j.issn.1002-4026.2021.02.010

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With calcium gluconate as the research object, a vacuum cooling crystallization experiment was performed to investigate the effects of time, temperature, stirring speed, and vacuum degree on the vacuum cooling crystallization of calcium gluconate. Results show that the factors affecting the crystallization rate of calcium gluconate are listed in the order of desceding degree of impact as vacuum degree, crystallization temperature, and stirring speed, among which the vacuum degree is a significant factor with P<0.05. The optimal process conditions for vacuum cooling crystallization of calcium gluconate are as follows: crystallization temperature is 50 °C, vacuum degree is 0.095 MPa, and stirring speed is 100 r/min. These results provide theoretical basis for technology and device development of calcium gluconate vacuum flash continuous evaporation crystallization.

Real-time inspection system for transmission line equipment based on Jetson-TX2

YANG Xue-Jie, CHEN Wen-Dong, XU Rong-Hao, LI Song-Lin, LI Jian-Ye

Shandong Science. 2021, 34(2): 81-89. doi:10.3976/j.issn.1002-4026.2021.02.011

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To solve the problem of low efficiency of inspection of transmission line equipment, this paper designs a real-time inspection system for transmission line equipment based on Jetson-TX2. The main control module of Jetson-TX2 based on YOLO v3 and a Pan/Tilt/Zoom(PTZ) camera control module are included in this system. The YOLO v3 algorithm model is accelerated by TensorRT, which is transplanted in Jetson-TX2 to complete the real-time identification and positioning of the device target in the video stream. The PTZ camera is controlled by Jetson-TX2 to realize the high-definition image acquisition of the device through the PID algorithm. The system's overall recognition accuracy for transmission line equipment can reach 95%, which can realize real-time video detection. It can effectively improve the efficiency of transmission line inspection.

Image restoration method based on partial differential equations

MIAO Xiao, ZHANG Xin-dong, TANG Quan, YANG Si-yuan

Shandong Science. 2021, 34(2): 90-95. doi:10.3976/j.issn.1002-4026.2021.02.012

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For the case in which the original model has the same weight at each reference point on a TV model, the paper propose a new concept whereby a diffusion function based on the gradient value of the pixels in the area to be repaired is constructed. The diffusion function is used to control the value of the contribution of each reference point. In addition, an adaptive iterative function for time parameters based on the idea of nonlinear diffusion is proposed. The diffusion function and adaptive iterative function work together to complete the image inpainting. Results of the experiment reveal that the new method proposed in this paper can achieve good processing effect in less time.

Application of solvent-free crystallization technology in the production of vitamin B₁₂

CHENG Jun-shan, LI He, YANG Ji-zong, PAN Li-hong, GU Xiao-fei, ZHANG Miao-jing

Shandong Science. 2021, 34(2): 96-103. doi:10.3976/j.issn.1002-4026.2021.02.013

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To prepare vitamin B₁₂ and to determine the optimal process parameters for the solvent-free crystallization technique, the purity and yield of the product were evaluated to optimize this technique using response surface methodology. The optimal process parameters were obtained as follows: evaporation temperature of 65 ℃, vacuum degree of 0.09 kPa, and concentration of 90 000 μg/mL prior to crystallization. It was shown that the solvent-free crystalization technique has high feasibility and effectiveness as the yield and quality of the final product were on par with that of solvent crystalization, if not better. While improving the safety of production, this technique cuts down pollution and eliminates certain procedures, thereby reducing the production cost and making it a good candidate for implementation in large-scale production.

Study on creep characteristics of sandstone and three-dimensional nonlinear mechanical model

LIU Fan-xi, ZHAO Li-cai, YU Jian-xing, JIANG Teng-jian

Shandong Science. 2021, 34(2): 104-113. doi:10.3976/j.issn.1002-4026.2021.02.014

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To describe the creep mechanical behavior of rocks, triaxial compression creep tests of sandstone under different confining pressures are conducted herein. Results show that the steady creep stage is a process of developing and expanding microcracks in rocks, and the steady creep rate and confining pressure increase the power function. The long-term strengths of sandstone under confining pressures of 5 MPa, 10 MPa, and 15 MPa are 19.8 MPa, 22.3 MPa, and 24.7 MPa, respectively. The long-term strength increases with the increase in confining pressure. Based on the nonlinear characteristics of rock creep, the viscoelastic modulus E（p） associated with confining pressure is defined. E（p，t） that can reflect the influence of rock creep by time and confining pressure is obtained using the derivation transformation, which is applied to the improved Burgers model to obtain a new one-dimensional creep constitutive model. It can be extended to three-dimensional stress state to obtain a new three-dimensional nonlinear mechanical model, identify creep test data, compare and analyze the prediction results, and prove the feasibility and rationality of the model. The research results shed light on the simulation of creep behavior of rock under three-dimensional stress state.

Existence of positive solutions for the nonlinear impulsive differential system boundary value problem

WANG Ming-gao, TANG Qiu-yun

Shandong Science. 2021, 34(2): 114-122. doi:10.3976/j.issn.1002-4026.2021.02.015

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By creating a special operator, the impulsive problem is transformed into a continuity problem. Then, we use the fixed point theorem of cone expansion and compression to investigate the boundary value problem of a second-order nonlinear impulsive differential system. Consequently, we confirm the existence of multiple positive solutions.

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