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Spinal cord injury has the characteristics of high mortality and disability rates, and the treatment of spinal cord injury has been a worldwide problem. With the deepening of spinal cord injury research and the advancement of treatment methods, the survival rate of patients has improved, but the clinical efficacy is still not ideal. New research has found that the immune response is involved in the entire process of pathological changes and regeneration and repair after spinal cord injury. Among them, the complement system plays an important role in the occurrence and development of spinal cord injury. This article mainly reviews the role of the complement system in secondary spinal cord injury and regeneration and repair after spinal cord injury, including the doubleedged sword effect of the complement system, the impact of the complement system on axonal regeneration and synaptic maintenance, and possible signaling pathways, with a view to improving the treatment of spinal cord injury, providing new treatment ideas.

To combat the crisis of today's synthetic polymers arising from unsustainable production and disposal, it is essential for the synthetic polymer community to reshape the current polymer industry with sustainable polymers. As an emerging class of sustainable polymers, the development of chemically depolymerizable polymers (CDPs), which can undergo closed-loop depolymerization/repolymerization cycles to reproduce virgin polymers without the loss of properties from recovered monomers, offers an ideal solution to preserve finite natural resources, provides a feasible solution to the end-of-life issue of polymer waste, and thereby establishes a circular materials economy. However, two grand key challenges have been encountered in the establishment of practically useful CDPs: how to balance polymerization and depolymerization ability and how to unify conflicted depolymerizability and physical properties. Accordingly, this critical review article presents our vision for summarizing feasible strategies to overcome the above two significant challenges and the design principles for constructing an ideal CDP by highlighting selected major progress made in this rapidly expanding field. [ABSTRACT FROM AUTHOR]

In recent years, perovskite solar cells (PSCs) have been attracting more and more attention. Although perovskite materials have high defect tolerance, defects remain the main factor that seriously affects the efficiency and stability of PSCs. Herein, the ionic liquid of 1-butyl, 3-methylimidazolium acetate ([BMIM][ACO]) was introduced into the SnO2/perovskite interface for the first time. Thanks to the dipoles formed by ILs spontaneously, the work function of SnO2 was reduced and the transport ability of carriers was improved as well. Moreover, the Lewis acidity and lone pair electrons of [BMIM][ACO] contribute to the passivation of I– defects, Pb2+ defects, or Pb-I anti site defects. In addition, the presence of dipoles will repel the approach of photogenerated holes and the reverse transport of electrons, reducing the recombination of defect sites through field-effect passivation. The solar cell with efficiency of 19.43% was obtained under such a dual passivation effect, and the best device maintained 75.21% of the initial efficiency after 80 h of continuous illumination. [ABSTRACT FROM AUTHOR]

BACKGROUND Sepiolite is a very important non-metallic mineral, which is widely used in aviation, animal husbandry, the chemical industry, environmental protection and other fields. Sepiolite is in great demand and needs a lot of analysis and testing. However, the existing sepiolite reference materials are inadequate and do not satisfy the needs of sepiolite composition analysis. Furthermore, there are no sepiolite reference materials in China, making it necessary to develop one. OBJECTIVES To prepare a reference material for composition analysis of sepiolite whose certified value components cover as many elements as possible. METHODS Sepiolite samples were collected from Xiangtan, Hunan Province. The samples were subjected to primary crushing, coarse-grain sieving, inactivation, fine grinding and fine grain sieving. After passing the initial inspection, samples were bottled and numbered. Random samples were taken for homogeneity test, stability test. 24 components were selected for homogeneity and stability test. RESULTS The results showed that the RSD of 20 components were less than 3%, and the F value of the variance test was less than the critical value of the list[F0.05(29, 60)=1.65], indicating that the homogeneity of the reference material was good. During the investigation period, the contents of 24 components had no significant change, indicating that the standard material was stable. Nine laboratories cooperated with traditional chemical analysis methods and modern instrumental analysis methods to determine the value. The final values were 63 components, covering major, trace and all rare earth elements. The contents of characteristic components MgO and LOI were 18% and 8.55%, respectively. These two components form a certain ladder with the existing reference materials, which can better satisfy the requirements of sepiolite composition analysis. CONCLUSIONS The developed sepiolite reference material can be used as the quality control standards for geological prospecting, geochemical investigation and testing of geological and mineral products, as well as for other industries to analyze similar materials. Moreover, in the process of developing the reference material, improvements and developments to the new methods will provide technical support for the subsequent development of the sepiolite reference material.

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a severe syndrome lacking efficient therapy and resulting in high morbidity and mortality. Although resveratrol (RES), a natural phytoalexin, has been reported to protect the ALI by suppressing the inflammatory response, the detailed mechanism of how RES affected the immune system is poorly studied. Pulmonary conventional dendritic cells (cDCs) are critically involved in the pathogenesis of inflammatory lung diseases including ALI. In this study, we aimed to investigate the protective role of RES via pulmonary cDCs in lipopolysaccharide (LPS)-induced ALI mice. Murine ALI model was established by intratracheally challenging with 5 mg/kg LPS. We found that RES pretreatment could mitigate LPS-induced ALI. Additionally, proinflammatory-skewed cytokines decreased whereas anti-inflammatory-related cytokines increased in bronchoalveolar lavage fluid by RES pretreatment. Mechanistically, RES regulated pulmonary cDCs’ maturation and function, exhibiting lower level of CD80, CD86, major histocompatibility complex (MHC) II expression, and IL-10 secretion in ALI mice. Furthermore, RES modulated the balance between proinflammation and anti-inflammation of cDCs. Moreover, in vitro RES pretreatment regulated the maturation and function of bone marrow derived dendritic cells (BMDCs). Finally, the adoptive transfer of RES-pretreated BMDCs enhanced recovery of ALI. Thus, these data might further extend our understanding of a protective role of RES in regulating pulmonary cDCs against ALI.

BACKGROUND Sepiolite is a widely used fibrous magnesium-rich silicate clay mineral. Sepiolite is mainly composed of silicon and magnesium, with minor aluminum, potassium, sodium and other impurities. Determination of the major element of sepiolite usually adopts the classical chemical analytical method. After the alkali melting treatment, the sample is determined by volumetric method, photometry and atomic absorption spectrometry, which is inefficient and time-consuming. Moreover, potassium and sodium cannot be simultaneously determined. OBJECTIVES To find an efficient method for the determination of seven major elements in sepiolite. METHODS The samples were digested by hydrofluoric acid, nitric acid, and perchloric acid. Contents of major elements such as Al2O3 were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The dosage of hydrofluoric acid was optimized. The analytical spectral lines were Al 396.153nm, Ti 334.940nm, K 766.490nm, Na 589.592nm, Ca 422.673nm, Mg 285.213nm and Fe 238.204nm, and elements were determined by axial observation. The content of magnesium in sepiolite was high, and there was a certain matrix effect during ICP-OES analysis. A series of high magnesium mixed standard solutions were prepared to match the matrix. RESULTS The linear correlation coefficient of the standard curve of each element was greater than 0.9990, the detection limits of the method were 0.53-3.25μg/g, the relative standard deviations (RSD, n=10) of the measured results were 0.66%-5.65%, and the recoveries of each element were 95.3%-108.5%. CONCLUSIONS Acid dissolution is easy to operate compared with the alkali fusion method. The results are consistent with those obtained by classical chemical analytical methods and thus meet the analytical requirements of sepiolite samples.

BACKGROUND The sampling weight can be as low as milligram level when the contents of rare earth elements in rock and soil samples are determined by inductively coupled plasma-mass spectrometry (ICP-MS). However, the size of 200 mesh samples requires 100mg to ensure representativeness, which makes it difficult for ICP-MS to make full use of its advantages of high sensitivity and small sampling volume. OBJECTIVES To establish the method for the determination of rare earth elements in ultra-fine rock and soil samples by ICP-MS with microwave digestion. METHODS A method was developed for the determination of rare earth elements in ultra-fine rock and soil samples by ICP-MS with microwave digestion. The ultra-fine rock and soil samples were prepared by the planetary superfine pulverizing machine with wet grinding. Some parameters influencing the preparation of ultra-fine rock and soil samples, including grinding method, grinding time and the proportion of grinding balls were optimized. Microwave digestion of ultrafine-grained rock and soil samples in a nitric acid-hydrofluoric acid-hydrogen peroxide solution system, the sampling amount was reduced to 5mg, the total acid amount was reduced to 0.25mL and the digestion time was reduced to 25 minutes. RESULTS The results indicated that the samples were best refined when the wet-milling was adopted with ethanol as a dispersant and the milling time was 10 minutes and 15 minutes for 200 mesh soil and rock samples, respectively. The material ratios were 7g materials, 500 grinding balls, 45mL dispersants for the preparation of ultra-fine soil samples, whereas 5g materials, 500 grinding balls, 45mL dispersants for the preparation of ultra-fine rock samples. The particle size distribution D95 of soil standard substance GBW07404 and GBW07447 can be as low as 7.51μm and 7.05μm, and the D95 of rock standard substance GBW07104 and GBW07121 can be 8.42μm and 8.30μm under the optimized conditions. Microwave digestion of ultrafine-grained rock sample GBW07104 in a nitric acid-hydrofluoric acid-hydrogen peroxide solution system, the sampling amount was reduced to 5mg, the total acid amount was reduced to 0.25mL, the digestion time was reduced to 25 minutes, and the measured value of rare earth elements was consistent with the certified value with the relative standard deviation is between 1.64% and 5.21%. CONCLUSIONS This method was used for the detection of rare earth elements in other ultra-fine standard materials (GBW07404, GBW07447 and GBW07121), which yielded the relative standard deviation of 0.17%-6.60%, meeting the first criterion of Geology and Minerals Laboratory Testing Quality Management Standards.

Black-phase formamidinium lead iodide (FAPbI3), with a narrow bandgap and high thermal stability, has emerged as an in-demand material for highly efficient perovskite solar cells (PSCs). In a two-step sequential deposition, the PbI2 film plays an important role in the formation of a perovskite film with desirable qualities. This paper explores using N-methyl-2-pyrrolidone (NMP), a strong Lewis base, and N,N-dimethylformamide (DMF) as a mixed precursor solvent (DMF/NMP) of PbI2 and reports on preparing PbI2 films with a porous morphology by thermal treatment. Porous PbI2 films ensure the diffusion and sufficient reaction of the formamidinium iodide solution to form a smooth perovskite film. In addition, a dynamic spin coating method is also introduced to improve the uniformity of the perovskite film. Both methods yield a pure α-phase FAPbI3 film immediately in the unannealed state, which is necessary for the perovskite film to maintain phase stability. Finally, PSCs with a power conversion efficiency of 21.20% (0.13 cm2) are fabricated and optimized. The unencapsulated PSCs retain 90% of the initial efficiency for 1000 hours in dry air and exhibit a good thermal stability when heated to 85 °C. [ABSTRACT FROM AUTHOR]

Aims: The basolateral amygdala (BLA) plays an integral role in anxiety disorders (such as post traumatic stress disorder) stem from dysregulated fear memory. The excitability of glutamatergic neurons in the BLA correlates with fear memory, and the afterhyperpolarization current (IAHP) mediated by small‐conductance calcium‐activated potassium channel subtype 2 (SK2) dominates the excitability of glutamatergicneurons. This study aimed to explore the effect of MPP2 interacts with SK2 in the excitability of glutamatergic neurons in the BLA and the extinction of conditioned fear in mice. Methods: Fear memory was analyzed via freezing percentage. Western blotting and fluorescence quantitative PCR were used to determine the expression of protein and mRNA respectively. Electrophysiology was employed to measure the excitability of glutamatergic neurons and IAHP. Results: Fear conditioning decreased the levels of synaptic SK2 channels in the BLA, which were restored following fear extinction. Notably, reduced expression of synaptic SK2 channels in the BLA during fear conditioning was caused by the increased activity of protein kinase A (PKA), while increased levels of synaptic SK2 channels in the BLA during fear extinction were mediated by interactions with membrane‐palmitoylated protein 2 (MPP2). Conclusions: Our results revealed that MPP2 interacts with the SK2 channels and rescues the excitability of glutamatergic neurons by increasing the expression of synaptic SK2 channels in the BLA to promote the normalization of anxiety disorders and provide a new direction for the treatment. [ABSTRACT FROM AUTHOR]

BACKGROUND Solid sampling technology applied in soil sample measurement has the limitation of sample size, and cannot be applied to the mainstream element analysis instrument. OBJECTIVES To determine the trace elements by smashing soil samples to micron scale by high-speed grinding technology and under the action of a dispersant. METHODS The ultra-fine grinding technology of soil samples was systematically studied. The sample was crushed to micron level in a few minutes in an ethanol medium. The prepared solid suspension was directly measured by ICP-MS, avoiding blockage of pneumatic atomizers. RESULTS The determination of the reference materials shows that the solid suspension still has interference when the particle size is 6.8μm. By adding a small amount of hydrofluoric acid and nitric acid to modify the solid suspension, the solid particle size was reduced and thereby the impact of the sample size was reduced. The 13 trace elements of lithium, beryllium, vanadium, chromium, nickel, copper, zinc, rubidium, strontium, cadmium, cesium, barium and lead were successfully determined by ICP-MS. Accuracy experiment showed that the maximum relative error is 10.5%±3% and most of the elements have a relative error less than 5%. The precision experiment showed that most elements have a relative standard deviation (RSD) of less than 5.4%. CONCLUSIONS The determination results meet the requirements of DZ/G 0130-2006 'Test of Geology and Mineral Resources Quality Management Standards'.

BACKGROUND Sepiolite is a fibrous hydrous magnesium rich silicate clay mineral with the content of rare earth elements between 1×10-7 and 1×10-5. There is no national standard method for the determination of rare earth elements in sepiolite. Determination of rare earth elements in rocks commonly uses ICP-MS. Sample pretreatments generally use closed digestion and alkaline fusion, but these two treatments are time consuming and inefficient. OBJECTIVES To find an efficient dissolution method for the determination of 15 rare earth elements in sepiolite. METHODS By comparing three sample pretreatment methods of nitrate hydrofluoric acid hydrogen peroxide, nitric acid-hydrofluoric acid and nitric-acid hydrogen peroxide, the nitric acid-hydrofluoric acid solution system was selected. Microwave digestion was carried out and the hydrofluoric acid was driven off to avoid the formation of insoluble fluorides from the hydrofluoric acid. The content of 15 rare earth elements was determined by ICP-MS. RESULTS Due to the high content of magnesium in sepiolite, two internal standards of 103Rh and 185Re are selected to compensate for the drift of analytical signals and to correct matrix effects. The recoveries of the method range from 91.2% to 110.9%. The detection limits are 0.002-0.011 μg/L, and the precisions are 0.81%-2.79%. CONCLUSIONS The result of this method is in good agreement with that of the closed acid-digestion ICP-MS method, and with a small amount of acid (7 mL), high digestion efficiency (1 h), and a lower detection limit.

BACKGROUND The reductive environment of uranium is the most important influencing factor of uranium mineralization. The study of various redox markers in interlayer oxidation bands is of great significance for finding interlayer oxidation zone sandstone-type uranium deposits. OBJECTIVES The reduction experiments were carried out on reducing materials commonly found in sandstone-type uranium deposits such as ferrous, sulfide, pyrite, ilmenite, humic acid, biogas, and hydrogen. The reduction capacity of ferrous ion, sulfur ion, pyrite and other reduction factors at room temperature and pressure was studied. METHODS By polarography and spectrophotometry experiments to determine U(Ⅵ) and U(Ⅳ) content respectively. Their reduction capacity was analyzed. RESULTS Iron ion and sulfur ion had strong reducing properties, andhumic acid had certain reducing properties. Such as pyrite, ilmenite experiment in different acidity and sage green sandstone water soaking experiments showed that the soaked solution of gray-green sandstone contained a certain amount of ferrous ions, and there was no sulfur ion. CONCLUSIONS These ferrous ions were the main reason for the strong reducibility of gray-green sandstone. It also indicated that the gray-green sandstone was one of the most important factors in the subsequent mineralization of sandstone type uranium deposit in Ordos area.

Recently, skyrmions are constructed in the system of localized spoof surface plasmons (LSSPs), showing topological robustness and near‐equidistant multi‐resonant response. Guided wave excitation of the LSSP skyrmions plays an elementary role in large‐scale planar integration and construction of complex networks. However, it is not investigated. In this study, the LSSP skyrmions are excited by guided waves supported by two kinds of widely used transmission lines, microstrip line and coplanar waveguide. Space‐coiling meta‐structures with different shapes that support LSSP skyrmions are etched on the ground planes as defected ground structures (DGSs). All structures including resonator, transmission line, input and output ports are in one plane. The structures are fabricated on printed circuit boards (PCBs) and the near‐equidistant multi‐resonant spectra of the LSSP skyrmions are measured. Moreover, to reduce the material loss, the structure is made on MgB2 superconducting film, and the quality factor (Q‐factor) is increased by seven times compared to the corresponding mode on PCB. This study paves the way for the massive planar integration of the LSSP skyrmions and the construction of complex networks with the LSSP skyrmions, and provides an idea for developing metasurfaces with low material loss in the microwave and terahertz bands. [ABSTRACT FROM AUTHOR]

The methanol extract of the seeds of Khaya ivorensis afforded two new mexicanolide limonoids, ivorensines A and B (1 and 2), together with one known compound, ruageanin D (3). The structures of the isolated compounds were established based on 1 D and 2 D (1H-1H COSY, HMQC, and HMBC) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated limonoids were tested in vitro for antimicrobial potentials against 5 pathogenic microorganisms. As a result, compounds 1–3 exhibited antimicrobial activity against the tested Gram negative bacteria at the minimum inhibitory concentration values less than 50 μg/ml. [ABSTRACT FROM AUTHOR]

Chemically recyclable, circular polymers continue to attract increasing attention, but rendering both catalysts for depolymerization and high‐performance polymers recyclable is a more sustainable yet challenging goal. Here we introduce a dual catalyst/polymer recycling system in that recyclable inorganic phosphomolybdic acid catalyzes selective depolymerization of high‐ceiling‐temperature biodegradable poly(δ‐valerolactone) in bulk phase, which, upon reaching suitable molecular weight, exhibits outstanding mechanical performance with a high tensile strength of ≈66.6 MPa, fracture strain of ≈904 %, and toughness of ≈308 MJ m−3, and thus markedly outperforms commodity polyolefins, recovering its monomer in pure state and quantitative yield at only 100 °C. In sharp contrast, the uncatalyzed depolymerization not only requires a high temperature of >310 °C but is also low yielding and non‐selective. Importantly, the recovered monomer can be repolymerized as is to reproduce the same polymer, thereby closing the circular loop, and the recycled catalyst can be reused repeatedly for depolymerization runs without loss of its catalytic activity and efficiency. [ABSTRACT FROM AUTHOR]

The powder pellet compression method for X-ray Fluorescence analysis is an ideal environmentally friendly sample preparation technique with the added advantages of being simple and having high efficiency. However, due to the impact of particle effects and mineral effects, its measurement error is within about 5%, which hinders the application of this technology in the detection of major elements. Powder pellet technology is mainly used in the determination of trace elements as well as the analysis field with less precision. In this study, the stream sediment and soil reference material were crushed to an average particle size about 4-5 μm within a few minutes by ultra-high-speed planetary pressure prototype. The method of ultra-fine pressed powder pellet sample to determine SiO2, Al2O3, Fe2O3, CaO, MgO and other major elements was established by using X-ray Fluorescence Spectrometry. Measurement precision (RSD) of the method for most of the major elements is less than 2%, and detection limits are 0.003%-0.021%, which is an improvement on the melting method detection limit (0.006%-0.081%), especially for small atomic sodium with four times improvement on the detection limit. The development of this ultra-fine powder compression method for stream sediment and soil, minimizes the impact of the particle size effect by crushing the sample into several microns. X-ray Diffraction analysis demonstrates that the mineral composition of river sediments and soil preparation is dominated by quartz. Therefore, the mineral composition is simple with negligible mineral effect. Measured data with added LOI normalized processing shows that normalized measurements for each element is consistent with the standard value. The accuracy of the method is a significant over the conventional pellet sampling method.

Polar vinyl polymers, a class of polymers with polar groups as side chains, have significant advantages over conventional nonpolar polyolefin materials in terms of viscosity, toughness, interfacial properties (dyeability and printability), and compatibility with solvents or other polymers. Among them, aromatic polar vinyl polymers are of interest because of their good heat resistance properties. In addition, stereoselective polymerization of aromatic polar vinyl monomers has been rapidly developed because the steric structure of the polymer has a significant impact on its physical properties. In this paper, we review the research progress of stereoselective polymerization catalysts for aromatic polar vinyl monomers in recent years, discuss in detail the influence of ligand structure, electronic effect of substituents, spatial site resistance effect, central rare earth metal species and polymerization solvents on the activity and stereoselectivity of polymerization reactions, and explore the possible mechanism of polymerization reaction. [ABSTRACT FROM AUTHOR]

Obstacle detection is the primary task of the Advanced Driving Assistance System (ADAS). However, it is very difficult to achieve accurate obstacle detection in complex traffic scenes. To this end, this paper proposes an obstacle detection method based on the local spatial features of point clouds. Firstly, the local spatial point cloud of a superpixel is obtained through stereo matching and the SLIC image segmentation algorithm. Then, the probability of the obstacle in the corresponding area is estimated from the spatial feature information of the local plane normal vector and the superpixel point-cloud height, respectively. Finally, the detection results of the two methods are input into the Bayesian framework in the form of probabilities for the final decision. In order to describe the traffic scene efficiently and accurately, the detection results are further transformed into a multi-layer stixel representation. We carried out experiments on the KITTI dataset and compared several obstacle detection methods. The experimental results indicate that the proposed method has advantages in terms of its Pixel-wise True Positive Rate (PTPR) and Pixel-wise False Positive Rate (PFPR), particularly in complex traffic scenes, such as uneven roads. [ABSTRACT FROM AUTHOR]

The development of modern society is closely related to polymer materials. However, the accumulation of polymer materials and their evolution in the environment causes not only serious environmental problems, but also waste of resources. Although physical processing can be used to reuse polymers, the properties of the resulting polymers are significantly degraded. Chemically recyclable polymers, a type of polymer that degrades into monomers, can be an effective solution to the degradation of polymer properties caused by physical recycling of polymers. The ideal chemical recycling of polymers, i. e., quantitative conversion of the polymer to monomers at low energy consumption and repolymerization of the formed monomers into polymers with comparable properties to the original, is an attractive research goal. In recent years, significant progress has been made in the design of recyclable polymers, enabling the regulation of the "polymerization‐depolymerization" equilibrium and closed‐loop recycling under mild conditions. This review will focus on the following aspects of closed‐loop recycling of poly(sulfur) esters, polycarbonates, polyacetals, polyolefins, and poly(disulfide) polymer, illustrate the challenges in this area, and provide an outlook on future directions. [ABSTRACT FROM AUTHOR]