Methyl 2-[4-(4-chloro­benzo­yl)phen­oxy]-2-methyl­propano­ate

In the title compound, C18H17ClO4, the dihedral angle between the mean planes of the benzene rings is 53.4 (1)°. Weak inter­molecular C—H⋯O inter­actions are observed

Structural basis for the assembly and quinone transport mechanisms of the dimeric photosynthetic RC-LH1 supercomplex

The reaction center (RC) and light-harvesting complex 1 (LH1) form a RC–LH1 core supercomplex that is vital for the primary reactions of photosynthesis in purple phototrophic bacteria. Some species possess the dimeric RC–LH1 complex with a transmembrane polypeptide PufX, representing the largest photosynthetic complex in anoxygenic phototrophs. However, the details of the architecture and assembly mechanism of the RC–LH1 dimer are unclear. Here we report seven cryo-electron microscopy (cryo-EM) structures of RC–LH1 supercomplexes from Rhodobacter sphaeroides. Our structures reveal that two PufX polypeptides are positioned in the center of the S-shaped RC–LH1 dimer, interlocking association between the components and mediating RC–LH1 dimerization. Moreover, we identify another transmembrane peptide, designated PufY, which is located between the RC and LH1 subunits near the LH1 opening. PufY binds a quinone molecule and prevents LH1 subunits from completely encircling the RC, creating a channel for quinone/quinol exchange. Genetic mutagenesis, cryo-EM structures, and computational simulations provide a mechanistic understanding of the assembly and electron transport pathways of the RC–LH1 dimer and elucidate the roles of individual components in ensuring the structural and functional integrity of the photosynthetic supercomplex

Structural basis for the assembly and electron transport mechanisms of the dimeric photosynthetic RC–LH1 supercomplex

AbstractThe reaction center (RC) and light-harvesting complex 1 (LH1) form a RC–LH1 core supercomplex that is vital for the primary reactions of photosynthesis in purple photosynthetic bacteria. Some species possess the dimeric RC–LH1 complex with an additional polypeptide PufX, representing the largest photosynthetic complex in anoxygenic phototrophs. However, the details of the architecture and assembly mechanism of the RC–LH1 dimer are unclear. Here we report seven cryo-electron microscopy (cryo-EM) structures of RC–LH1 supercomplexes from Rhodobacter sphaeroides. Our structures reveal that two PufX polypeptides are positioned in the center of the S-shaped RC–LH1 dimer, interlocking association between the components and mediating RC–LH1 dimerization. Moreover, we identify a new transmembrane peptide, designated PufY, which is located between the RC and LH1 subunits near the LH1 opening. PufY binds a quinone molecule and prevents LH1 subunits from completely encircling the RC, creating a channel for quinone/quinol exchange. Genetic mutagenesis, cryo-EM structures, and computational simulations enable a mechanistic understanding of the assembly and electron transport pathways of the RC–LH1 dimer and elucidate the roles of individual components in ensuring the structural and functional integrity of the photosynthetic supercomplex.</jats:p

Different Concentrations of Doxycycline in Swine Manure Affect the Microbiome and Degradation of Doxycycline Residue in Soil

Antibiotic residues that enter the soil through swine manure could disturb the number, community structure and functions of microbiota which could also degrade antibiotics in soil. Five different concentrations of doxycycline (DOX) incorporated into swine manure were added to soil to explore the effects of DOX on microbiota in soil and degradation itself. The results showed that the soil microbiome evolved an adaptation to the soil containing DOX by generating resistance genes. Moreover, some of the organisms within the soil microbiome played crucial roles in the degradation of DOX. The average degradation half-life of DOX in non-sterile groups was 13.85 ± 0.45 days, which was significantly shorter than the 29.26 ± 0.98 days in the group with sterilized soil (P &lt; 0.01), indicating that the soil microbiome promoted DOX degradation. DOX addition affected the number of tetracycline resistance genes, depending on the type of gene and the DOX concentration. Among these genes, tetA, tetM, tetW, and tetX had significantly higher copy numbers when the concentration of DOX was higher. In contrast, a lower concentration of DOX had an inhibitory effect on tetG. At the same time, the microbial compositions were affected by the initial concentration of DOX and the different experimental periods. The soil chemical indicators also affected the microbial diversity changes, mainly because some microorganisms could survive in adversity and become dominant bacterial groups, such as the genera Vagococcus and Enterococcus (which were associated with electrical conductivity) and Caldicoprobacter spp. (which were positively correlated with pH). Our study mainly revealed soil microbiota and DOX degradation answered differently under variable concentrations of DOX mixed with swine manure in soil

High pressure geochemistry: Preface

International audienceHigh pressure geochemistry: Preface The origin and history of the Earth are manifested as the evolutionary processes of chemistry and physics of its interiors, which can be recognized by deciphering the geochemical signals recorded in minerals and rocks. Deep interiors of the Earth and other rocky planets are under both extreme pressure and temperature, i.e., approximately 360 gigapascals (GPa) and as high as 7000 K at the center of the Earth. So far, many questions on Earth's interiors remain equivocal, such as the compositions and mineralogy of the mantle and core, the causes of chemical and physical heterogeneities of the mantle, origins of magma and petroleum, the role of fluid-rock interaction in the crustal evolution and earthquake generation, the behavior and partition of elements and chemical species, chemical dynamics of the degassing process, among other processes, which have attracted much attention of scientists. The materials in the interior domains of Earth and other planets experience the extreme processes of high pressure and high temperature (high P-T) conditions. Not only does high temperature, but also high pressure severely affects the behavior of atoms and molecules, chemical dynamics of reactions, and existing states of materials. However, traditional investigations usually neglect the chemical reactions under high P-T conditions. Thus, the high P-T chemical reactions and processes are among the most important factors in the Earth's evolution, which are involved in various geological processes, such as mantle metasomatism, element differentiation, isotopic fractionation, magma evolution, ore formation, alteration of rocks, earthquake generation, etc. Therefore, studies of the geochemical behavior of materials under high P-T conditions are fundamental to understand the physicochemical properties of the Earth's interior. High-pressure experiments and theoretical simulations are powerful tools to explore the Earth's interiors in addition to the geophysical techniques, analysis of natural samples and meteorite. This Special Issue of High Pressure Geochemistry in Geoscience Frontiers assembles contributions that present results of high pressure geochemistry, concerning mainly the behavior and partition of elements, hydration and dehydration of minerals, origin of magma, reaction between minerals and magma, effect of chemical composition (as well as volatiles) on the transport property of mineral/rock, gas diffusion, phase transitions and occurrence states of materials under high P-T conditions. Chemical interaction between melts and mineral, partial melting of rocks show new evidence for the origin of magmas. The experimental work on dehydration and partial melting of amphibolite at 1.5 GP

Effect of Extracellular Vesicles on Neural Functional Recovery and Immunologic Suppression after Rat Cerebral Apoplexy

Background: Previous studies have demonstrated that mesenchymal stem cells (MSCs) can promote the recovery of neural function after cerebral apoplexy by secreting multiple cytokines. In addition, cell factor-derived extracellular vesicles play an important role in recovery of neural function. The aim of this study was to determine the effect of extracellular vesicles on neural functional recovery and brain tissue remodeling after cerebral apoplexy in a rat model. Methods: The rat models with local ischemic stroke was established and three random groups were created. In groups A and B, human bone marrow-derived MSCs and MSC-derived extracellular vesicles were transplanted into rats. In the control group (group C), only normal saline was injected. Then, we evaluated motor coordination ability, pathologic changes of the brain, immune responses in the central and peripheral nervous systems, regeneration of blood vessels, and nervous tissue in 4 weeks after cerebral apoplexy. Results: Obvious regeneration of blood vessels and nervous tissues were identified in groups A and B. There was no significant difference with respect to coordination between groups A and B, but coordination in groups A and B was significantly better than the control group. Immunohistochemical staining of brain tissue showed that extracellular vesicles exerted no effect on infiltration of immune cells in the central nervous system. Weakened immune suppression was noted 1 week after cerebral apoplexy, which provided a favorable environment for remodeling of brain tissue. Conclusion: MSC-derived extracellular vesicles accelerated neural functional recovery after cerebral apoplexy. The weakened immune suppression was beneficial to remodeling of brain tissue

A Precise Visual Method for Narrow Butt Detection in Specular Reflection Workpiece Welding

During the complex path workpiece welding, it is important to keep the welding torch aligned with the groove center using a visual seam detection method, so that the deviation between the torch and the groove can be corrected automatically. However, when detecting the narrow butt of a specular reflection workpiece, the existing methods may fail because of the extremely small groove width and the poor imaging quality. This paper proposes a novel detection method to solve these issues. We design a uniform surface light source to get high signal-to-noise ratio images against the specular reflection effect, and a double-line laser light source is used to obtain the workpiece surface equation relative to the torch. Two light sources are switched on alternately and the camera is synchronized to capture images when each light is on; then the position and pose between the torch and the groove can be obtained nearly at the same time. Experimental results show that our method can detect the groove effectively and efficiently during the welding process. The image resolution is 12.5 μm and the processing time is less than 10 ms per frame. This indicates our method can be applied to real-time narrow butt detection during high-speed welding process

Role of prenatal imaging in the diagnosis and management of fetal facio-cervical masses

Abstract Congenital facio-cervical masses can be a developmental anomaly of cystic, solid, or vascular origin, and have an inseparable relationship with adverse prognosis. This retrospective cross-sectional study aimed at determining on the prenatal diagnosis of congenital facio-cervical masses, its management and outcome in a large tertiary referral center. We collected information on prenatal clinical data, pregnancy outcomes, survival information, and final diagnosis. Out of 130 cases of facio-cervical masses, a total of 119 cases of lymphatic malformations (LMs), 2 cases of teratoma, 2 cases of thyroglossal duct cyst, 4 cases of hemangioma, 1 case of congenital epulis, and 2 cases of dermoid cyst were reviewed. The accuracy of prenatal ultrasound was 93.85% (122/130). Observations of diameters using prenatal ultrasound revealed that the bigger the initial diameter is, the bigger the relative change during pregnancy. Magnetic resonance imaging (MRI) revealed that 2 cases of masses were associated with airway compression. In conclusion, ultrasound has a high overall diagnostic accuracy of fetal face and neck deformities. Prenatal US can enhance the management of ambulatory monitoring and classification. Furthermore, MRI provided a detailed assessment of fetal congenital malformations, as well as visualization of the trachea, presenting a multi-dimensional anatomical relationship

Studies on Annihilation and Coreactant Electrochemiluminescence of Thermally Activated Delayed Fluorescent Molecules in Organic Medium

Very recently, there is a great research interest in electrochemiluminescence (ECL) featuring thermally activated delayed fluorescence (TADF) properties, i.e., TADF-ECL. It is appealing since the earlier reports in this topic well-confirmed that this strategy has a great potential in achieving all-exciton-harvesting ECL efficiency under electrochemical excitation, which is a breakthrough in the topic of organic ECL. However, organic phase electrochemistry and ECL studies surrounding TADF-ECL are still extremely rare. Especially, the ECL spectra of previous reported TADF emitters are still very different from their PL spectra. In this work, we systematically measure and discuss the liquid electrochemistry and ECL behavior of two typical TADF molecules in organic medium. Most importantly, we verify for the first time that the ECL spectra of them (coreactant ECL mode) are identical to their PL spectra counterparts, which confirms the effectiveness of TADF photophysical properties in the coreactant ECL mode in practice