Parameters and surrounding rock control of gob-side driving under double key stratum after roof cutting.

Taking the return-airway 4204 with roof cutting in Longquan Coal Mine as the engineering background, roof structure, key parameters, and deviatoric stress evolution were studied. Conclusion: The Key Stratum within a 4-8 times mining height is considered as Near Key Stratum. Cutting the roof makes it possible to form a cantilever structure of the Key Stratum on the solid coal side, which is more conducive to the stability of gob-side roadway. During cutting angle of 90-55°, the deviatoric stress increases linearly, and the increase rate is coal pillar > solid coal > roof > floor. While cutting length from 0 to 35 m, the deviatoric stress decreases linearly, and the decreasing range: coal pillar > solid coal > roof > floor. When coal pillar width is from 30 to 4 m, the deviatoric stress of left side and floor presents a "single peak" distribution. The deviatoric stress of coal pillar changes from an asymmetric "double peak" to a bell-shaped distribution, and the deviatoric stress of roof changes from a "single peak" to an asymmetric "double peak" distribution. Under same coal pillar width, the deviatoric stress of left, coal pillar and roof after roof cutting decreases most obviously, followed by the floor. Finally, the coal pillar width is 8 m, the cutting angle is 75°, the cutting length is 20 m, and the hole spacing is 1.0 m. The support scheme is bolt + metal mesh + steel belt + anchor cable combined support. The stable period of roadway is about 10 days.

Extraction of alumina and silica from high-silica bauxite by sintering with sodium carbonate followed by two-step leaching with water and sulfuric acid.

Efficient utilization of high-silica bauxite and minimization of bauxite residue are of great significance for the sustainable development of the alumina industry. In this paper, a novel process is proposed to extract Al2O3 and SiO2 from high-silica bauxite without residue discharge, that is, sintering bauxite with Na2CO3 followed by two-step leaching with water and sulfuric acid. The effects of the sintering parameters on the process were investigated, and the phase transformations during sintering and leaching were revealed by using phase diagram, thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) methods. When the mixture of the high-silica bauxite and Na2CO3 with mole ratio of Na2O/(Al2O3 + SiO2) of 1 was sintered at 950 °C for 30 min, diaspore and kaolinite were primarily converted into Na1.95Al1.95Si0.05O4 and an amorphous phase, respectively. In the water leaching process, Na1.95Al1.95Si0.05O4 was dissolved while the amorphous phase underwent some transformations to form the water leaching residue, resulting in ∼84% of Al2O3 being extracted for alumina production. In the sulfuric acid leaching process, the amorphous phase in the water leaching residue dissolved, resulting in ∼13% of Al2O3 and ∼86% of SiO2 being extracted for the production of polyaluminium ferric sulfate (PAFS) and silica gel, respectively. The silica gel had a high purity, containing more than 88% of SiO2 after drying.

Delayed irrigation at the jointing stage increased the post-flowering dry matter accumulation and water productivity of winter wheat under wide-precision planting pattern.

BACKGROUND: The North China Plain (NCP) faces a severe water shortage, and the amount of rainfall cannot guarantee the growth and development of winter wheat. Therefore, it is important to explore a suitable irrigation and planting pattern to solve the problem of water shortage in this region. RESULTS: A 4-year experiment was carried out in the NCP during 2015-2019. The main plots included two planting patterns: a wide-precision planting pattern (W) and a conventional planting pattern. Two irrigation regimes were established for each planting pattern: 60-mm irrigation at the jointing stage (I1) and 60-mm irrigation delayed 10 days at the jointing stage (I2). The soil water consumption, dry matter translocation, grain yield and crop water productivity were investigated. The results showed that WI2 treatment obtained the highest grain yield and crop water productivity. The wide-precision planting pattern could significantly decrease soil water consumption; however, delayed irrigation effectively reduced soil water consumption only in normal rainfall years. The coupling of delayed irrigation at the jointing stage and a wide-precision planting pattern significantly enhanced dry matter accumulation after flowering and the contribution of dry matter accumulation after flowering to grain yield during the growing seasons. WI2 could decrease the evapotranspiration and improve the grain yield, thus increasing crop water productivity. CONCLUSION: The combination of a wide-precision planting pattern and delayed irrigation at the jointing stage was the appropriate agronomic practice for efficient grain yield and crop water productivity in the North China Plain. © 2022 Society of Chemical Industry.

Wheat Escapes Low Light Stress by Altering Pollination Types.

Although low light stress seriously affects florets fertility and grain number during the reproductive period, crops can be fertilized by heterologous pollen to alleviate the reduction of grain number. However, wheat is strongly autogamous, how to change to outcross after low light remains unclear. To understand the mechanisms of this change process, an approach combined morphological, physiological, and transcriptomic analyses was performed under low light stress imposed at the young microspore stage the booting stage from tetrad to uni-nucleate microspores stage. The results showed that low light stress caused pollen abortion, and the unfertilized ovary is fertilized by heterologous pollen after floret opening. Compared to control, the opening angle of lemma and glume were increased by 11.6-48.6 and 48.4-78.5%, respectively. The outcross of stressed wheat compensated for the 2.1-18.0% of grain number loss. During this process, phytohormones played an important role. Jasmonic acid (JA) and methyl jasmonate (MeJA) levels in spikelets were increased. Meanwhile, lignin and cellulose content decreased, and genes associated with cell wall related GO terms were enriched. Among the differentially expressed genes (DEGs), were identified 88-710 transcription factors genes, of which some homologs in Arabidopsis are proposed to function in lignin and cellulose, influencing the glume and lemma opening. Our finding can provide new insight into a survival mechanism to set seeds through pollination way alteration in the absence of self-fertilization after the stress of adversity.

[Effects of brackish water irrigation on grain quality characteristics and yield of winter wheat]. / 咸水灌溉对冬小麦籽粒品质特性和产量的影响.

Brackish water resource is widely distributed in the North China Plain, which has not been effectively utilized. Using brackish water for irrigation can alleviate water resource conflict in the well-irrigated area and solve the problem of groundwater over-exploitation of the North China Plain. A long-term experiment (since 2006) was conducted to investigate the effects of brackish water irrigation on the quality and yield of winter wheat in the North China Plain. There were five salinity degrees of irrigation water, i.e. 1, 2, 4, 6, and 8 g·L-1, respectively. The results showed that higher salinity degree of irrigation water (4-8 g·L-1) significantly increased water absorption, development time, sedimentation, wet gluten content, and protein content, but decreased the stabilization time, flour yield, and gluten index. There was no significant difference between the treatments of 1 g·L-1 and 2 g·L-1 on grain yield and yield components, but the treatment of 2 g·L-1 significantly improved grain quality, including water absorption, development time, sedimentation, wet gluten, and protein content. Higher salinity degree of irrigation water (4-8 g·L-1) treatments significantly decreased spike number (44.0%-60.7%) and grain yield (35.6%-64.7%), compared with 1 g·L-1 treatment. Results of principal component analysis showed that 2 g·L-1 treatment had the best overall effect with no significant decrease in grain yield and quality of grain. This study could provide theoretical basis and technical support for use of brackish water in the North China Plain.

Carbon emission and water use efficiency response to tillage methods and planting patterns of winter wheat in the North China Plain.

BACKGROUND: Implementing sustainable farming practices for winter wheat (Triticum aestivum L.) in the North China Plain may be a way to reduce carbon emissions. No tillage generally results in less net CO2 loss from farmland, but no tillage also reduces the grain yield and water use efficiency (WUE) of winter wheat. Wide-precision planting of winter wheat may enhance the grain yield and WUE; however, it is not known precisely how tillage and planting patterns affect CO2 exchange, grain yield and WUE. METHODS: In this study, two tillage methods (conventional tillage, T and no tillage, NT) and two planting patterns (conventional planting, C and wide-precision planting, W) were used in two consecutive winter wheat growing seasons. RESULTS: Compared with the T treatments, the NT treatments had significantly lower cumulative net CO2 emissions in 2015-2016 and 2016-2017 (30.8 and 21.3%, respectively), and had lower grain yields (9.0 and 9.4%, respectively) and WUE (6.0 and 7.2%, respectively). The W treatments had a compensating effect on grain yield failure and reduced cumulative net CO2 emissions more than C treatments, thereby increasing WUE, reducing carbon emissions per unit water consumption, and increasing the yield carbon utilization efficiency (YCUE). The lowest cumulative CO2 emissions and highest YCUE were observed for NT with W treatment. Results from this analogous tillage experiment indicated that NT and W farming practices provide an option for reducing carbon emissions and enhancing WUE and YCUE for sustainable winter wheat development.

Synthesis and Electromagnetic Interference Shielding Performance of Ti3SiC2-Based Ceramics Fabricated by Liquid Silicon Infiltration.

In this work, Ti3SiC2-based ceramics were fabricated by the infiltration of liquid silicon into TiC preform by incorporating a small amount of Al. Al can play a catalytic role to promote the formation of TiC twins before liquid silicon infiltration (LSI), which leads to the increase of transformation efficiency from TiC to Ti3SiC2 in the LSI process. When the Al content in the TiC preform increases to 9 wt.%, the volume content of Ti3SiC2 reaches 85 vol.%, revealing the high electromagnetic interference shielding effectiveness of 39 dB in the frequency range of 8.2-12.4 GHz. The results indicate that it is an effective way to synthesize Ti3SiC2-based ceramics with excellent electromagnetic shielding performance.

[Study and design of the Q-switched Nd:YAG laser control system based on S3C2410].

This paper presents a design of the control system for the Q-switched Nd:YAG laser, which is based on S3C2410, and the emphasis is laid on its hardware & software's design. The LCD interface with the function of a touch screen is implemented by the Qt/Embedded graphical interface application programs.