AF2-mutation: adversarial sequence mutations against AlphaFold2 in protein tertiary structure prediction

Proteins are essential macromolecules that perform functions according to their conformational dynamics. Studying the conformational changes induced by protein mutations is the standard approach used to understand the mechanisms underlying mutation-related physiological and pathological processes. To enhance efficiency and decrease the expense of biological experiments, we introduce a method to generate mutated proteins through adversarial attacks on the AlphaFold2 (AF2) model. We explored the structure change of adversarial protein sequences predicted by AF2 compared to the wild type protein’s structure. CASP14 experiments indicated that altering only three residues via replacement, deletion, or insertion led to a 46.61 points difference in AF2’s predictions, according to the Local Distance Difference Test (lDDT). We applied this method to the transmembrane lipid transporter SPNS2 to identify crucial residues and suggest potential alternative conformations, thereby streamlining the experimental phase in structure determination and mechanistic studies

Mechanisms of dust emissions from lakes during different drying stages in a semi-arid grassland in northern China

Semi-arid playas are important to grassland ecosystem species as an important source of global dust emissions. However, there is a lack of data on dust emissions during the different drying stages of grassland playas. In this study, we initially conducted the field experiments on two types of surfaces (intermittently dried and permanently dried) in playas located in semi-arid regions in northern China, and we measured dust emissions at five wind speeds in spring when wind erosion was frequent. The results showed that the intermittently dried surface was more prone to wind erosion, which was primarily due to the formation of a loose and fragile salt crust on the surface. In addition, the proportion of salt in the dust was higher than that for the permanently dried surfaces. Nevertheless, the total horizontal dust flux (1.13–2.3 g/cm2·min) from the intermittently dried surface was only 5%–15% that of the permanently dried surface (7.47–42.86 g/cm2·min). The dust content varied linearly with the height of the intermittently dried surface, and varied exponentially with the height of the permanently dried surface. The particles collected on the intermittently dried surface were larger (&amp;lt;63 μm) than those collected on the permanently dried surface (&amp;lt;10 μm), and the unit mass concentration of each ion (mainly Na+, Cl−, and SO42−) in the salt dust was also higher for the intermittently dried surface than for the permanently dried surface. Although salt dust was continuously released from the intermittently dried surface, the total amount released each time was limited. These results indicate that to attenuate the damage of salt dust storms, priority should be given to protecting permanently dried surfaces and reducing the supply of salt dust particles at the surface.</jats:p

Characteristics of Soil Particle Sizes and Fractal Parameters under Different Plantation Types of Populus alba

Vegetation plays a leading role in restoring desert ecosystems and increasing productivity. In this study, we elucidate the improvement effects of different restoration areas of Populus alba on the soil particle distribution, sedimentation environment, and fractal characteristics. We selected the restoration areas of P. alba &times; Caragana&nbsp;korshinskii (YN), P.&nbsp;alba &times; Hedysarum&nbsp;leave (YY), and P.&nbsp;alba &times; Hedysarum&nbsp;scoparium (YH), which have a history of twenty-one years. We analyzed the soil nutrients, soil particle size, soil particle size parameters, soil fractal dimension (D) values, and soil multifractal parameters at soil depths of 0&ndash;80 cm. We found that the YN, YY, and YH significantly increased the soil nutrients and soil fine particles (p &lt; 0.05) and changed the deposition pattern of the soil particles in the sandy area. The YN, YY, and YH promote soil particle refinement and reduce the sorting performance of the soil particles. The vegetation promotes extremely positive-skewed and very leptokurtic soil particle distributions. The D values in the YN, YY, and YH restoration areas increased by 7.62%&ndash;27.94%, 7.36%&ndash;26.28%, and 7.10%&ndash;17.92%, respectively, relative to those of the LS. The construction of the different restoration areas of P.&nbsp;alba has made the distribution of the soil particles nonuniform. Compared with the YY and YH plantations, the distribution range of the soil particles in the YN plantation is wider, and the distribution heterogeneity is greater. In addition, we found that the fractal parameters are influenced by the soil physicochemical properties, the depositional environment, and vegetation factors. Therefore, we believe that D values and multifractal parameters are necessary as additional information for desert soil texture improvement. The results of this study provide a scientific and theoretical basis for the future revegetation of deserts

Optical Design and Polarization Analysis for Full-Polarization Underwater Imaging Lens

Underwater polarization imaging has emerged as a fundamental technique for detecting and imaging underwater targets. However, the effectiveness of this technique is hampered by the low light intensity and optical system deformation induced by water pressure in deep-water environments, particularly for the detection of polarized signals. To address this issue, a wide-field-of-view oil-immersion lens tailored for deep-sea operations is designed, offering robust imaging performance and an extensive observation range. A Mueller matrix is deployed to scrutinize the polarization properties of the entire optical system across diverse fields of view, and the measurement errors in the polarization degree under incident polarization states are discussed. Simulation results demonstrate that the measurement error for linearly polarized light is greater than that for circularly polarized light. Therefore, the system adopts circularly polarized light as the active illumination source, characterized by minimal polarization effects and high detection accuracy. Finally, a deep-sea camera lens is produced and manufactured. The resulting lens is shown to pass a test in a hydrodynamic simulator machine, demonstrating that it can operate properly and capture images

Advanced Study of Optical Imaging Systems for Virtual Reality Head-Mounted Displays

Driven by the rapid innovation of science and technology and industrial manufacturing technology, virtual reality display technology has developed rapidly. At present, the application of virtual reality display technology is expanding in many fields such as military, medical, aviation and education. This paper analyzes the imaging principle of the human vision system and the optical performance requirements of VR heads-up display, summarizes the current design scheme of VR heads-up optical imaging system, focuses on the principle and index parameters of each optical system, and compares the advantages and disadvantages of different schemes. The development prospects and directions of virtual reality headset displays are also prospected

The role of typical low vertical lattice sand barriers in regulating the airflow field on wind-eroded surfaces of photovoltaic power plants

Deserts are ideal places to build photovoltaic (PV) power plants, but this plants often face challenges from strong wind and sand activities during the operation and maintenance period, exploring the effects of PV power plant construction on wind disturbances and the control of wind and sand activities by different sand fixation measures is necessary. This study investigated the wind speed outside the PV plant, inside the plant without sand barriers measures (CK), and under three different sand-protecting barriers (gauze sand barriers (GZ), polylactic acid sand barriers (PLA), and grass grid sand barriers (GG)) inside the plant. Though calculated the surface roughness, friction velocity, wind protection effectiveness, and wind turbulence to determined the effectiveness of the barriers by these indexes comprehensively. The results show that: (1) The construction of desert PV power plant can effectively reduce the wind speed. Compared with CK, all three mechanical sand barriers within the plant reduced wind speed. Especially when the height less than 50cm, the GZ sand barriers reduced the wind speeds the most, with an average reduction rate of 101.5%. (2) All three sand barriers increased soil roughness and friction velocity within the power station. (3) At heights below 50cm, the GZ and GG sand barriers have better wind protection effectiveness than PLA sand barriers, while at hights above 100cm, the wind protection effect of PLA and GG sand barriers became less significant or even negligible (4) The wind disturbance caused by the three sand fixation measures increased with wind speed, the comprehensive performance of GZ and PLA sand barriers was superior than that of GG sand barriers and CK

Soil Infiltration Properties Are Affected by Typical Plant Communities in a Semi-Arid Desert Grassland in China

A process of infiltration from the soil surface to form soil water is known as soil infiltration; this is the only way for plants to absorb and use soil water. This process is closely related to nutrient migration, surface runoff, and soil erosion. The objectives of this study were to quantify the effect of typical plant communities on soil infiltration performance, reveal the interaction between soil infiltration rate and soil characteristics and plant roots, and determine the primary influencing elements on the Xilamuren grassland. The ring knife method was used to determine the soil infiltration rate at the 0&ndash;30 cm soil layer of six typical vegetation communities. The results indicated that the infiltration rate of the Koeleria macrantha community was highest at the soil depth of 0&ndash;5 cm, while that of the Convolvulus ammannii community was lowest, reaching 4.25 mm&middot;min&minus;1 and 0.53 mm&middot;min&minus;1, respectively. The soil infiltration rate of different plant communities gradually declined with the increment of soil depth. The strongest correlations were found between bulk density, total porosity, organic matter, root characteristics, and soil infiltration rate. The bulk density, initial water content, capillary porosity, and clay content were the primary influencing factors acting on soil infiltration in the region. Other factors indirectly impacted the infiltration rate by modifying bulk density, which was a crucial limiting factor determining the infiltration rate in the research region. The study&rsquo;s findings will give theoretical and practical assistance for the prevention and management of soil deterioration and grassland restoration in this area