Studies on Synthesis and Structure-Activity Relationship (SAR) of Derivatives of a New Natural Product from Marine Fungi as Inhibitors of Influenza Virus Neuraminidase

Based on the natural isoprenyl phenyl ether from a mangrove-derived fungus, 32 analogues were synthesized and evaluated for inhibitory activity against influenza H1N1 neuraminidase. Compound 15 (3-(allyloxy)-4-hydroxybenzaldehyde) exhibited the most potent inhibitory activity, with IC50 values of 26.96 μM for A/GuangdongSB/01/2009 (H1N1), 27.73 μM for A/Guangdong/03/2009 (H1N1), and 25.13 μM for A/Guangdong/ 05/2009 (H1N1), respectively, which is stronger than the benzoic acid derivatives (~mM level). These are a new kind of non-nitrogenous aromatic ether Neuraminidase (NA) inhibitors. Their structures are simple and the synthesis routes are not complex. The structure-activity relationship (SAR) analysis revealed that the aryl aldehyde and unsubstituted hydroxyl were important to NA inhibitory activities. Molecular docking studies were carried out to explain the SAR of the compounds, and provided valuable information for further structure modification

A Novel OxyR Sensor and Regulator of Hydrogen Peroxide Stress with One Cysteine Residue in Deinococcus radiodurans

In bacteria, OxyR is a peroxide sensor and transcription regulator, which can sense the presence of reactive oxygen species and induce antioxidant system. When the cells are exposed to H2O2, OxyR protein is activated via the formation of a disulfide bond between the two conserved cysteine residues (C199 and C208). In Deinococcus radiodurans, a previously unreported special characteristic of DrOxyR (DR0615) is found with only one conserved cysteine. dr0615 gene mutant is hypersensitive to H2O2, but only a little to ionizing radiation. Site-directed mutagenesis and subsequent in vivo functional analyses revealed that the conserved cysteine (C210) is necessary for sensing H2O2, but its mutation did not alter the binding characteristics of OxyR on DNA. Under oxidant stress, DrOxyR is oxidized to sulfenic acid form, which can be reduced by reducing reagents. In addition, quantitative real-time PCR and global transcription profile results showed that OxyR is not only a transcriptional activator (e.g., katE, drb0125), but also a transcriptional repressor (e.g., dps, mntH). Because OxyR regulates Mn and Fe ion transporter genes, Mn/Fe ion ratio is changed in dr0615 mutant, suggesting that the genes involved in Mn/Fe ion homeostasis, and the genes involved in antioxidant mechanism are highly cooperative under extremely oxidant stress. In conclusion, these findings expand the OxyR family, which could be divided into two classes: typical 2-Cys OxyR and 1-Cys OxyR

Supercritical CO2 Exposure-Induced Surface Property, Pore Structure, and Adsorption Capacity Alterations in Various Rank Coals

Carbon dioxide (CO2) has been used to replace coal seam gas for recovery enhancement and carbon sequestration. To better understand the alternations of coal seam in response to CO2 sequestration, the properties of four different coals before and after supercritical CO2 (ScCO2) exposure at 40 °C and 16 MPa were analyzed with Fourier Transform infrared spectroscopy (FTIR), low-pressure nitrogen, and CO2 adsorption methods. Further, high-pressure CO2 adsorption isotherms were performed at 40 °C using a gravimetric method. The results indicate that the density of functional groups and mineral matters on coal surface decreased after ScCO2 exposure, especially for low-rank coal. With ScCO2 exposure, only minimal changes in pore shape were observed for various rank coals. However, the micropore specific surface area (SSA) and pore volume increased while the values for mesopore decreased as determined by low-pressure N2 and CO2 adsorption. The combined effects of surface property and pore structure alterations lead to a higher CO2 adsorption capacity at lower pressures but lower CO2 adsorption capacity at higher pressures. Langmuir model fitting shows a decreasing trend in monolayer capacity after ScCO2 exposure, indicating an elimination of the adsorption sites. The results provide new insights for the long-term safety for the evaluation of CO2-enhanced coal seam gas recovery

Research on the path of agriculture sustainable development based on the concept of circular economy and big data

In order to improve the reliability and scientificity of the path of agriculture sustainable development, guided by the concept of circular economy, this paper combines data mining technology to construct a path analysis system of agricultural sustainable development and establishes a one-dimensional discrete dynamic model of the interaction between the stock of renewable resources and the output. Moreover, this paper discusses the impact of resource-based industries’ output on the sustainable use of resources and establishes a two-dimensional discrete dynamic control model for resource stock and resource development speed. In addition, this paper mainly studies the relationship between resource stock and output when the speed of resource development is managed and controlled, and builds a system structure model based on the actual needs of agricultural development. Finally, this paper designs an experiment to analyse the performance of the system model constructed in this paper. The research results show that the system constructed in this paper has a certain guiding effect on the sustainable development of agriculture, and it can be applied to practice

Research on model predictive control model in application of shearer height-adjusting system

In view of the problems of lower stability and poor precision existed in present shearer height-adjustment system, which used electromagnetic switch valve to adjust height of drum, a model predictive control model of the shearer height-adjustment system was established through adding model predictive controller in conventional model of the shearer height-adjusting system and taking MG300/700-WD type AC traction shearer as the research object. The switching frequency of electromagnetic switch valve and working hours were reduced by adjusting sampling time and predictive time domain length of model predictive controller, the drum can be realize accurate and real time height adjustment according to the target height. Simulation results show that the shearer height-adjustment system based on model predictive control model can achieve stability in 6 s after given input compared with the conventional model, switch frequency of the electromagnetic switch valve is reduced, overshoot amount is decreased by 28.8%, stability and real-time performance of the system are improved

On the Factors of Impact Pressure in Supercritical CO₂ Phase-Transition Blasting—A Numerical Study

Carbon dioxide phase transition blasting (CO2-PB) technology is an effective and economical technology used for breaking rocks. The use of CO2-PB can significantly reduce the vibration damage to surrounding rocks. There is little research on the shockwave generated by the CO2-PB, and simulation can better show the flow field characteristics. In order to clarify the mechanism of its blasting load process, a theoretical analysis and a numerical model were developed to study the flow-field characteristics and the impact pressure of CO2-PB. Our results show that the CO2 absorbs heat from the surrounding environment, producing a significant low-temperature area. The overpressure is significantly lower than the driving gas pressure to the ambient pressure, limiting the maximum over-pressure that can be obtained. When the pressure in CO2-PB reaches 100 MPa, the shockwave is about 4.25 MPa. As the distance increases, the peak value of the shockwave decays rapidly. As the dimensionless distance increases from 1 to 5, the dimensionless overpressure decreases from 1 to 0.23. Under the same blasting pressure, increasing the filling pressure and increasing the filling volume slightly reduce the initial pressure of the shockwave. In the shock stage, strong compression is formed on the surface of the shockwave, resulting in a higher peak pressure value. Meanwhile, the stable pressure is influenced by the target distance, blasting pressure, and CO2-PB length

Mining machine cutting load classification based on vibration signal

There are some errors and lags in the way of judging the cutting load type of the mining machine manually. In order to solve the above problem, a classification method of mining machine cutting load based on wavelet packet decomposition and sparrow search algorithm optimized BP neural network (SSA-BPNN) is proposed. The method comprises two parts of signal feature extraction and mode classification. In the part of signal feature extraction, the collected vibration signal of the mining machine rocker arm is decomposed by wavelet packet to obtain the energy of each subband and the total energy of the signal. After normalization, feature vectors representing different load types are obtained. The principal component analysis is used to reduce the dimensions of the feature vector. In the mode classification part, SSA is used to optimize the initial weight and threshold of BPNN. The feature vector is used as the input of SSA-BPNN to realize the load classification and recognition. Taking the MG500/1170-AWD1 mining machine as an object, the magnetic acceleration sensor is attached to the shell of the rocker arm of the mining machine near the bracket side. The vibration signals of the mining machine drum under three working conditions of no-load, cutting bauxite and rock are collected and tested. The experimental results show that the vibration signals under different cutting loads have some differences in the energy of each sub-band. This result indicates that the energy features obtained by wavelet packet decomposition can be used as feature vectors to distinguish different load types. Compared with BPNN, SSA-BPNN has faster convergence speed and higher recognition accuracy, and the recognition accuracy of load classification is 95.3%

Surface Properties and Pore Structure of Anthracite, Bituminous Coal and Lignite

Properties of coal surface and pore structure are important aspects to be investigated in coal preparation and utilization. In order to investigate the limits of different probe methods, a comprehensive approach was comparatively used to probe surface properties and pore structure of anthracite, bituminous coal and lignite. Surface morphology of the three coal samples was analyzed by scanning electron microscopy (SEM). Combining mercury intrusion porosimetry (MIP), physisorption method with carbon dioxide (CO2) at 273 K and nitrogen (N2) at 77 K was used to quantify a broad pore size distribution of coals, while FT-IR and water vapor sorption methods were used to study the coal surface properties. The results show that wedge-shaped pores develop with the increase of coal rank due to compression effect. The determined specific surface area (SSA) and pore volume of N2 decrease with the increase of coal rank, while CO2 SSA and pore volume are of a kind of U-shaped function of coal rank. MIP results indicate that that the pore size of 10–100 nm accounted for 70.7–97.5% of the total volume in the macropore range. Comparison of different methods indicates that micropores cannot be fully covered by the standard probes. CO2 adsorption technique can only probe micropores in the range of 0.5 nm to 0.9 nm. Water vapor is not an effective probe to detect the micropores in coals, due to that the water clusters is mainly filled in mesopores and macropores. The results also show that both water vapor adsorption and FT-IR analysis can provide qualitative information of coal surface, rather than qualification of functional groups

Combined effects of pore structure and surface chemistry on water vapor adsorption characteristics of coal: Equilibrium, thermodynamic and kinetic studies

The combined effects of surface chemistry and pore structure on water vapor adsorption characteristics of coal were studied by evaluating the equilibrium, thermodynamic and kinetic properties. Four coal samples of different rank were fully characterized with gas (N2 and CO2) sorption and Fourier Transform infrared spectroscopy (FTIR) methods. Then measurements of water vapor adsorption equilibrium and kinetics were undertaken at elevated temperatures. Equilibrium and kinetic data were fitted by the modified BET model and the unipore model, respectively. The thermodynamic parameters, as well as diffusion activation energy were estimated based on the adsorption data. The results demonstrate that water vapor adsorption depends on the surface chemistry but unrelated to the pore structure, because the pore space is not completely filled by water molecules even at the saturation pressure. The monolayer adsorption capacity decreases with increasing coal rank. Moreover, water vapor needs lower work to attain equilibrium on high-ranked coal. Also, the binding affinity of water molecule with primary sites is stronger than secondary sites. Furthermore, the diffusion coefficient decreases with coal rank, and the diffusion activation energy for high-volatile bituminous is higher than the other coals, as a result of the complexity and poor connectivity of its pore network

Preventive Security-Constrained Optimal Power Flow Considering UPFC Control Modes

The successful application of the unified power flow controller (UPFC) provides a new control method for the secure and economic operation of power system. In order to make the full use of UPFC and improve the economic efficiency and static security of a power system, a preventive security-constrained power flow optimization method considering UPFC control modes is proposed in this paper. Firstly, an iterative method considering UPFC control modes is deduced for power flow calculation. Taking into account the influence of different UPFC control modes on the distribution of power flow after N-1 contingency, the optimization model is then constructed by setting a minimal system operation cost and a maximum static security margin as the objective. Based on this model, the particle swarm optimization (PSO) algorithm is utilized to optimize power system operating parameters and UPFC control modes simultaneously. Finally, a standard IEEE 30-bus system is utilized to demonstrate that the proposed method fully exploits the potential of static control of UPFC and significantly increases the economic efficiency and static security of the power system