Search

Vagus nerve stimulation (VNS) is an emerging neuromodulation therapy that has been used in post⁃stroke rehabilitation. In recent years, VNS combined with rehabilitation has been used to improve upper limb motor function in stroke patients, but the mechanisms and optimal stimulation parameters are still unclear. In this paper, we summarize the evidence from basic and clinical studies of VNS combined with rehabilitation for post⁃stroke upper limb motor disorders, and discuss the possible mechanisms and optimal stimulation parameters, provide new ideas for the rehabilitation of post⁃stroke upper limb motor disorders.

In order to study the nature of interaction between Ba2+ and the KDP crystal surface, the adsorption behavior of Ba2+ on the KDP (100) surface was calculated by using density functional theory (DFT). The results show that the adsorption energies of Ba2+ on the KDP (100) surface are negative, indicating the adsorption processes are spontaneous and exothermic. Three types of adsorption configurations are formed after structure optimizations, and final adsorption positions are top sites on O atoms or bridge sites between two O atoms. The most stable adsorption system can be observed when Ba2+ on the bridge site between two O atoms within a phosphate group. In the three different adsorption configurations, Ba2+ can form ionic bonds with the surface O atoms, while interactions between Ba2+ and the surface H atoms exhibit covalent character. The P-O, H-O, and K-O bonds on the KDP (100) surface are elongated or shortened after Ba2+ adsorption, and the structure of hydrogen bonds on the surface also have been changed significantly.

Xinhua phosphorus is a sedimentary phosphate deposit in China with strong REEs enrichment. In this study, Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES) as well as rock-mineral identification, major and trace elements analysis together with sedimentology theory have been used to study geochemical characteristics of REEs in Xinhua phosphate rocks. ∑REEs of Xinhua phosphate rocks range from 800×10-6 to 1200×10-6 and are dominated by LREEs and Yttrium. REEs occur in collophanite by isomorphism dominantly. REEs pattern curves show remarkably negative Ce anomaies with values ranging from 0.28 to 0.36 in Xinhua phosphate rocks, which are similar to those of Kunyang phosphate rocks, indicating phosphorus in the south of the upper Yangtze was formed in an oxidative environment and precipitated at the stable epicontinental sea of the passive continental margin. However, REEs pattern curves of the upper black shales and weak Ce and Eu anomalies are different from those of Xinhua phosphate rocks, which reflect black shales were formed in a deep and bathyal sea of a reductive environment. The Meishucunian period had a transgression process and the Meishucunian stage had an upward deep regressive sequence, the boundary between phosphate rocks and black shales possibly being a third-order even less scale sequence boundary. All of this sedimentology information is helpful to reveal the sequence of stratigraphy and marine sedimentary environment, which provides evidence for biological outbreak and stratigraphy sequence of early Cambrian in the Yangtze area, South China.

Tuberculosis (TB), the leading cause of death from bacterial infections worldwide, results from infection with Mycobacterium tuberculosis (Mtb). The antitubercular agents delamanid (DLM) and pretomanid (PMD) are nitroimidazole prodrugs that require activation by an enzyme intrinsic to Mtb; however, the mechanism(s) of action and the associated metabolic pathways are largely unclear. Profiling of the chemical‐genetic interactions of PMD and DLM in Mtb using combined CRISPR screening reveals that the mutation of rv2073c increases susceptibility of Mtb to these nitroimidazole drugs both in vitro and in infected mice, whereas mutation of rv0078 increases drug resistance. Further assays show that Rv2073c might confer intrinsic resistance to DLM/PMD by interfering with inhibition of the drug target, decaprenylphophoryl‐2‐keto‐b‐D‐erythro‐pentose reductase (DprE2), by active nicotinamide adenine dinucleotide (NAD) adducts. Characterization of the metabolic pathways of DLM/PMD in Mtb using a combination of chemical genetics and comparative liquid chromatography‐mass spectrometry (LC‐MS) analysis of DLM/PMD metabolites reveals that Rv0077c, which is negatively regulated by Rv0078, mediates drug resistance by metabolizing activated DLM/PMD. These results might guide development of new nitroimidazole prodrugs and new regimens for TB treatment. [ABSTRACT FROM AUTHOR]

The Proterozoic Eon is a critical period of the Earth's evolution, and the study of its rock records in this period is important for understanding the Earth's evolution in the Precambrian. The correct interpretation of rock genesis is the basis of the study of rock geotectonics and the premise of revealing the change of earth environment based on rock records. A set of silicon-rich layered rocks generally developed at the bottom of the Changcheng System in the North China Craton, which is considered to be a set of marine quartz sandstones and siliceous rocks formed by shallow metamorphism in rift valley deposition. This paper focuses on the silica-rich layered rocks of Changzhougou Formation at the bottom of the Great Wall System exposed in Huyugou, Changping, Beijing. Through detailed field geological observations, petrological and mineral analysis of typical samples, SEM/EDS (Scanning Electron Microscopy/X-ray Spectroscopy), CL (Cathodoluminescence) imaging, in-situ LA-ICP-MS (Laser Ablation-inductively Coupled Plasma Mass Spectrometry) analysis of quartz, and petrological, micro-thermometry, muffle furnace heating-quenching experiments, and SEM/EDS, EPMA (Electron Probe Microanalysis), LRM (Laser Raman Microscopy) analysis of melt inclusions in quartz, a new understanding of the volcanic origin of the silicon-rich stratified rocks at the bottom of the Great Wall System has been proposed. The results indicate that the silicon-rich stratified rocks at the bottom of the Great Wall System include two types: clastic structures (previously defined as quartz "sandstone") and mosaic structures (previously defined as "quartzite"). The main mineral compositions are quartz and K-feldspar, with minor amounts of zircon, rutile, and other minerals. In the clastic structure rocks, quartz and K-feldspar clasts exhibit angular to subangular shapes, and K-feldspar shows no signs of clay alteration at the edges. The CL of quartz in the two types of rocks mostly shows blue-purple luminous characteristics. Additionally, the formation temperature estimated by the quartz titanium saturation thermometer is concentrated between 550 ~ 650°C, indicating characteristics of high-temperature quartz. Both types of rocks contain iron-titanium-rich two-phase melt inclusions in quartz and K-feldspar. Micro-thermometry results of the melt inclusions show that during the heating process to 1 000°C, the composition of the two-phase immiscible melt inclusions changes continuously, when the temperature reaches 1 000°C, with a color reversal occurring at about 1 050°C, and critical homogenization around 1 350°C. Muffle furnace heating-quenching experiments also confirmed that the two-phase melt inclusions in the samples quenched after heating to 1 350°C became homogeneous. SEM/EDS and EPMA results indicate that the main components of the melt inclusions are iron and titanium oxides, with the dark part being relatively rich in iron and the light part being relatively rich in titanium, and the Fe/Ti ratio of the two phases of the melt inclusions varies greatly. LRM analysis results show that both phases of the melt inclusions are amorphous. Integrating the structural characteristics of the rocks, the CL luminescence characteristics of quartz, the formation temperature estimation of quartz, and the micro-thermometry results of the melt inclusions in quartz, it is believed that the siliceous strata at bottom of the Changcheng System should be siliceous volcanic rocks and volcaniclastic rocks. This indicates that there was a large-scale siliceous volcanic activity in the North China Craton during the Paleoproterozoic, which is related to the rifting of the Columbia Supercontinent. It provides new evidence for the geological evolution of the North China Craton in the Proterozoic. The discovery of iron-titanium-rich melt inclusions in quartz also offers new perspectives on the formation of Precambrian magmatic iron and titanium deposits, particularly the enrichment mechanism of iron and titanium during the magmatic process. [ABSTRACT FROM AUTHOR]

Marine sedimentary phosphorites usually contain high rare earth elements (REEs) content, especially the heavy REEs (HREEs), which account for over 30% of the total REEs. The phosphorites may became another important source for HREEs in the future. Phosphorite deposits are widely distributed in China and most of them are found in Yunnan, Guizhou, Sichuan Provinces, etc. High REEs abundances are confirmed in the Zhijin phosphorite deposit in Guizhou Province and with total REEs resource over 3 Mt. The collophanite and apatite are the main host phase for both REEs and P, and the collophanite has complex chemical composition. There are still controversies for the mineral and chemical composition of collophanite. Based on detailed petrological, mineralogical, SEM/EDS, XRD, FIB-TEM and LA-ICP-MS results of phosphorites in Zhijin deposit, this paper discuss the mineral composition of phosphorites and the origin of the complex chemical composition of collophanite. The results show that the most phosphorites in the deposit show the pelletal texture, which is composed of phosphorous pellets and carbonate cement. The mineral composition of the phosphorous pellet is very complex, including mainly fluorapatite and dolomite, and with minor quartz, dolomite, pyrite (some oxidized into limonite), muscovite, solid bitumen and barite. The mineral composition of the cement is mainly dolomite, with minor quartz, pyrite, barite, and trace amounts of zircon, rutile, and liebigite (possibly formed by oxidation of other uranium minerals). The FIB-TEM results show that the cryptocrystalline part of the outer layer of phosphorus pellet is composed of nanoscale mineral aggregates including mainly nanoscale fluorapatite, and small amount of nanoscale dolomite, pyrite and organic matter. The mineral composition of collophanite is similar to that of phosphorus pellet. The discovery of nanoscale fluorapatite, dolomite, pyrite, and organic matter in phosphorite provides reliable evidence for explaining the chemical complexity of collophanite. The discovery of solid bitumen and liebigite in phosphorites, as well as high REEs content in organic matter, also provides new evidence for an alternative occurrence of U and REEs in phosphorites. [ABSTRACT FROM AUTHOR]

Shifang-type phosphorite deposit is an important type of phosphorite deposit in China, which is characterized by large scale, high phosphorus grade, and enrichment in rare earth elements (REEs). However, the enrichment regularity and resource potential of REEs in this type of deposit are not studied in detail. This study takes the typical Shifang-type phosphorite deposit in Mianzhu, Sichuan Province, as the research object. Based on field geological investigation, the distribution and enrichment characteristics of REEs in the deposit are explored through microscopic petrographic observation, scanning electron microscope/energy disperse spectroscopy imaging, and whole-rock geochemical analysis for the phosphorus-bearing layers (phosphorite layer, dark grey and maroon S-P-Al-Sr-rich layers) and their roof and floor rocks (dolomite) in the mining area. In turn, the potential resource of REEs in Shifang-type phosphorite deposits in Sichuan Province is discussed. The results showed that the total REEs (La-Lu+Y) contents in the roof and floor dolomites of the phosphorus-bearing layers are very low (13.6x10-6 on average), the REEs contents in the phosphorite are medium (280.0x10-6 on average), while the REEs contents in the S-P-Al-Sr-rich layers are extremely high (2 053.9x10-6 on average), especially the maroon S-P-Al-Sr-rich layer (up to 3 257.2x10-6). Together with previously published REEs content data from adjacent phosphorite deposit, the average REEs content in S-P-Al-Sr-rich layers in the Shifang-type phosphorite deposits in Sichuan Province is 2 259. 4x10-6 with the maximum up to 3 286.8x10-6, of which the average concentration of medium and heavy REEs (Sm ~ Lu+Y) is 1 276.9x10-6 with the maximum up to 2 213.0x10-6, accounting for 55.1% of the total REEs. REEs contents in the Shifang-type phosphorite deposits in Sichuan Province are much higher than those in ion adsorption-type REEs deposits in southern China, Zhijin REEs-bearing phosphorite deposit, and REEs-rich deep-sea sediments. According to preliminary estimates, the total potential REEs resources associated with the Shifang-type phosphorite deposits in Sichuan Province can reach 252 000 tons, 156 000 tons of which are medium and heavy REEs. The potential medium and heavy REEs resources in the S-P-Al-Sr-rich layer alone can reach 96 000 tons. Therefore, the Shifang-type phosphorite deposits in Sichuan Province have important economic and social value, and the development and utilization of REEs in these deposits are expected to alleviate the current shortage of medium and heavy REEs in China. [ABSTRACT FROM AUTHOR]