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Background: Premenstrual syndrome/premenstrual dysphoric disorder is a serious condition affecting women worldwide, causing clinically significant distress or interference. Therefore, solving these diseases has become the utmost concern worldwide, culminating in numerous studies. In this study, we performed bibliometric analysis on the 100 most cited papers with the aim of identifying research hot spots and trends in this field., Methods: We screened the Science Citation Index Expanded (SCIE) of Web of Science (WOS) to identify the top 100 cited studies on PMS/PMDD. Next, we analyzed relevant literature from various journals, countries/regions, institutions, authors, and keywords. Finally, we used VOSviewer and Citespace software to generate knowledge maps and identify hot spots and trends., Results: The top 100 highly cited studies were published in 55 journals, between 1999 and 2017, across 24 countries/regions around the world. Most articles were published in Obstetrics and Gynecology, whereas Psych neuroendocrinology had the largest average number of citations per paper. The United States had the highest number of publications, followed by England, Canada, and Sweden. The top three institutions that published the highly cited literature were the University of Pennsylvania, Yale University, and National Institute of Mental Health (NIMH). Obstetrics, Gynecology, Psychiatry, and Reproductive Biology were the main research directions, whereas the top 10 Co-occurrence of Keywords included double-blind, fluoxetine, efficacy, prevalence, epidemiology, phase sertraline treatment, depression, progesterone, placebo, and placebo-controlled trial. Results from cluster analysis indicated that more comprehensive epidemiology and steroid pathogenesis have gradually become the hot spots and trends., Conclusion: These findings demonstrated that bibliometric analysis can intuitively and rapidly reveal the frontiers and hot spots of research in PMS/PMDD. Notably, epidemiology, steroid pathogenesis, GABAA receptor delta subunits, and double-blind placebo-controlled trials are potential areas of focus for future research., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Gao, Zhang, Wang, Mou, Zhu, Wang and Gao.)

Photosystem II (PSII) has a number of hydrogen-bonding networks connecting the manganese cluster with the lumenal bulk solution. The structure of PSII from Thermosynechococcus vulcanus (T. vulcanus) showed that D1-R323, D1-N322, D1-D319 and D1-H304 are involved in one of these hydrogen-bonding networks located in the interfaces between the D1, CP43 and PsbV subunits. In order to investigate the functions of these residues in PSII, we generated seven site-directed mutants D1-R323A, D1-R323E, D1-N322R, D1-D319L, D1-D319R, D1-D319Y and D1-H304D of T. vulcanus and examined the effects of these mutations on the growth and functions of the oxygen-evolving complex. The photoautotrophic growth rates of these mutants were similar to that of the wild type, whereas the oxygen-evolving activities of the mutant cells were decreased differently to 63-91% of that of the wild type at pH 6.5. The mutant cells showed a higher relative activity at higher pH region than the wild type cells, suggesting that higher pH facilitated proton egress in the mutants. In addition, oxygen evolution of thylakoid membranes isolated from these mutants showed an apparent decrease compared to that of the cells. This is due to the loss of PsbU during purification of the thylakoid membranes. Moreover, PsbV was also lost in the PSII core complexes purified from the mutants. Taken together, D1-R323, D1-N322, D1-D319 and D1-H304 are vital for the optimal function of oxygen evolution and functional binding of extrinsic proteins to PSII core, and may be involved in the proton egress pathway mediated by Y Z ., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

To study the abnormal failure of magnesium anodes for buried pipelines in marine engineering in the unique environment of mudflats, a strain of a sulfate-reducing prokaryote (SRP) was isolated from pipe-laying soil, and identified as Desulfovibrio sp. HQM3. Weight-loss test, electrochemical measurements, SEM, EDS, XRD, and CLSM techniques were used to study the effect of corrosion on the AZ31B magnesium alloy. Under the influence of SRP, the magnesium alloy corroded severely at rates up to 1.31 mm/year in the mudflat environment. SRP accelerated corrosion by 0.3mm/year. Pitting occurred on the samples in both abiotic and biotic systems. The pitting depth reached 163.47 μm in the biotic system after 14 days. The main composition of a petal-like corrosion product was Mg(OH) 2 . The results show that a mudflat environment can lead to an accelerated corrosion of magnesium alloys.

This study seeks prevent and alleviate the failure of magnesium alloy anodes in pipelines, which we suspect is a problem related to SRB. The electrochemical corrosion behaviour of two kinds of magnesium alloys, AZ31B and AZ63B, in 3.5 wt.% NaCl solution with sulphide or phosphide-the two main inorganic metabolites of sulphate-reducing bacteria-were studied by electrochemical tests combined with other characterisation methods such as scanning electron microscopy and X-ray diffraction. The results show that the corrosion film formed by inorganic metabolites of SRB's initial stage of corrosion (1-3 d) can lead to the corrosion of magnesium alloys. However, the loose and porous corrosion product film cannot protect the substrate effectively. The inorganic metabolites in the solution can accelerate the corrosion of the surface of magnesium alloy after the corrosion products have fallen off. This study provides a theoretical basis for alleviating the premature failure of magnesium alloy anodes and for corrosion protection in the future.

Photosystem II (PSII) is a multisubunit pigment-protein complex and catalyses light-induced water oxidation, leading to the conversion of light energy into chemical energy and the release of dioxygen. We analysed the structures of two Psb28-bound PSII intermediates, Psb28-RC47 and Psb28-PSII, purified from a psbV-deletion strain of the thermophilic cyanobacterium Thermosynechococcus vulcanus, using cryo-electron microscopy. Both Psb28-RC47 and Psb28-PSII bind one Psb28, one Tsl0063 and an unknown subunit. Psb28 is located at the cytoplasmic surface of PSII and interacts with D1, D2 and CP47, whereas Tsl0063 is a transmembrane subunit and binds at the side of CP47/PsbH. Substantial structural perturbations are observed at the acceptor side, which result in conformational changes of the quinone (Q B ) and non-haem iron binding sites and thus may protect PSII from photodamage during assembly. These results provide a solid structural basis for understanding the assembly process of native PSII., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Photosystem II (PSII) is a multisubunit pigment-protein complex and catalyzes light-driven water oxidation, leading to the conversion of light energy into chemical energy and the release of molecular oxygen. Psb27 is a small thylakoid lumen-localized protein known to serve as an assembly factor for the biogenesis and repair of the PSII complex. The exact location and binding fashion of Psb27 in the intermediate PSII remain elusive. Here, we report the structure of a dimeric Psb27-PSII complex purified from a psbV deletion mutant (ΔPsbV) of the cyanobacterium Thermosynechococcus vulcanus , solved by cryo-electron microscopy. Our structure showed that Psb27 is associated with CP43 at the luminal side, with specific interactions formed between Helix 2 and Helix 3 of Psb27 and a loop region between Helix 3 and Helix 4 of CP43 (loop C) as well as the large, lumen-exposed and hydrophilic E-loop of CP43. The binding of Psb27 imposes some conflicts with the N-terminal region of PsbO and also induces some conformational changes in CP43, CP47, and D2. This makes PsbO unable to bind in the Psb27-PSII. Conformational changes also occurred in D1, PsbE, PsbF, and PsbZ; this, together with the conformational changes occurred in CP43, CP47, and D2, may prevent the binding of PsbU and induce dissociation of PsbJ. This structural information provides important insights into the regulation mechanism of Psb27 in the biogenesis and repair of PSII., Competing Interests: The authors declare no competing interest.

PsbO-D158 is a highly conserved residue of the PsbO protein in photosystem II (PSII), and participates in one of the hydrogen-bonding networks connecting the manganese cluster with the lumenal surface. In order to examine the role of PsbO-D158, we mutated it to E, N or K in Thermosynechococcus vulcanus and characterized photosynthetic properties of the mutants obtained. The growth rates of these three mutants were similar to that of the wild type, whereas the oxygen-evolving activity of the three mutant cells decreased to 60-64% of the wild type. Fluorescence kinetics showed that the mutations did not affect the electron transfer from Q A to Q B , but slightly affected the donor side of PSII. Moreover, all of the three mutant cells were more sensitive to high light and became slower to recover from photoinhibition. In the isolated thylakoid membranes from the three mutants, the PsbU subunit was lost and the oxygen-evolving activity was reduced to a lower level compared to that in the respective cells. PSII complexes isolated from these mutants showed no oxygen-evolving activity, which was found to be due to large or complete loss of PsbO, PsbV and PsbU during the process of purification. Moreover, PSII cores purified from the three mutants contained Psb27, an assembly co-factor of PSII. These results suggest that PsbO-D158 is required for the proper binding of the three extrinsic proteins to PSII and plays an important role in maintaining the optimal oxygen-evolving activity, and its mutation caused incomplete assembly of the PSII complex.

PsbV (cytochrome c 550 ) is one of the three extrinsic proteins of photosystem II (PSII) and functions to maintain the stability and activity of the Mn 4 CaO 5 cluster, the catalytic center for water oxidation. PsbV-Y137 is the C-terminal residue of PsbV and is located at the exit of a hydrogen-bond network mediated by the D1-Y161-H190 residue pair. In order to examine the function of PsbV-Y137, four mutants, PsbV-Y137A, PsbV-Y137F, PsbV-Y137G, and PsbV-Y137W, were generated with Thermosynechococcus vulcanus (T. vulcanus). These mutants showed growth rates similar to that of the wild-type strain (WT); however, their oxygen-evolving activities were different. At pH 6.5, the oxygen evolution rates of Y137F and Y137W were almost identical to that of WT, whereas the oxygen evolution rates of the Y137A, Y137G mutants were 64% and 61% of WT, respectively. However, the oxygen evolution in the latter two mutants decreased less at higher pHs, suggesting that higher pHs facilitated oxygen evolution probably by facilitating proton egress in these two mutants. Furthermore, thylakoid membranes isolated from the PsbV-Y137A, PsbV-Y137G mutants exhibited much lower levels of oxygen-evolving activity than that of WT, which was found to be caused by the release of PsbV. In addition, PSII complexes purified from the PsbV-Y137A and PsbV-Y137G mutants lost all of the three extrinsic proteins but instead bind Psb27, an assembly cofactor of PSII. These results demonstrate that the PsbV-Tyr137 residue is required for the stable binding of PsbV to PSII, and the hydrogen-bond network mediated by D1-Y161-H190 is likely to function in proton egress during water oxidation.

The variation in the morphology and electronic structure of copper during the electroreduction of CO 2 into valuable hydrocarbons and alcohols was revealed by combining in situ surface- and bulk-sensitive X-ray spectroscopies with electrochemical scanning electron microscopy. These experiments proved that the electrified interface surface and near-surface are dominated by reduced copper. The selectivity to the formation of the key C-C bond is enhanced at higher cathodic potentials as a consequence of increased copper metallicity. In addition, the reduction of the copper oxide electrode and oxygen loss in the lattice reconstructs the electrode to yield a rougher surface with more uncoordinated sites, which controls the dissociation barrier of water and CO 2 . Thus, according to these results, copper oxide species can only be stabilized kinetically under CO 2 reduction reaction conditions., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Catalytic transformation of CO x (x = 1, 2) with renewable H 2 into valuable fuels and chemicals provides practical processes to mitigate the worldwide energy crisis. Fe-based catalytic materials are widely used for those reactions due to their abundance and low cost. Novel iron carbides are particularly promising catalytic materials among the reported ferrous catalysts. Recently, a series of strategies has been developed for the preparation of iron carbide nanoparticles and their nanocomposites. Control synthesis of FeC x -based nanomaterials and their catalytic applications in CO x hydrogenation and electrochemical hydrogen evolution reaction (HER) are reviewed. The discussion is focused on the unique catalytic activities of iron carbides in CO x hydrogenation and HER and the correlation between structure and catalytic performance. Future synthesis and potential catalytic applications of iron carbides are also summarized., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Electrochemical oxidation has attracted vast interest as a promising alternative to traditional chemical processes in fine chemical synthesis owing to its fast and sustainable features. An electrocatalytic membrane reactor (ECMR) with a three-dimensional (3D) electrode has been successfully designed for the selective oxidation of alcohols with high current efficiency to the corresponding acids or ketones. The anode electrode was fabricated by the in situ loading of one-dimensional (1D) Co 3 O 4 nanowires (NWs) on the conductive porous Ti membrane (Co 3 O 4 NWs/Ti) via the combination of a facile hydrothermal synthesis and subsequent thermal treatment. The electrocatalytic oxidation (ECO) results of alcohols exhibited superior catalytic performance with a higher current efficiency on the Co 3 O 4 NWs/Ti membrane compared with those of Co 3 O 4 nanoparticles on the Ti membrane (Co 3 O 4 NPs/Ti). Even under low reaction temperatures such as 0 °C, it still displayed a very high ECO activity for alcohol oxidation in the ECMR. For example, >99% conversion and 92% selectivity toward benzoic acid were obtained for the benzyl alcohol electrooxidation. The electrode is particularly effective for the cyclohexanol oxidation, and a selectivity of >99% to cyclohexanone was achieved at 0 °C, higher than most reported noble-metal catalysts under the aerobic reaction conditions. The extraordinary electrocatalytic performance of the 3D Co 3 O 4 NWs/Ti membrane electrode demonstrates the significant influence of morphology effect and engineering interfaces in membrane electrodes on the electrocatalytic activity and charge transfer process of nanocatalysts. Our results propose that similar membrane electrodes serve as versatile platforms for the applications of 1D nanomaterials, porous electrodes, and ECMRs.

Bacterial polysaccharides play important roles both in medicine and industry. Due to the development of bacterial genome sequencing, many gene clusters related to the biosynthesis of bacterial polysaccharide have been found, aligned and analyzed. Despite of their complex composition and structures, different bacterial polysaccharides are biosynthesized via similar pathways. This review discussed the research development of the biosynthetic mechanism of different bacterial polysaccharides, with emphasis on the glycosyltransferases and polymerases involved in the biosynthetic pathway.

The Myc/Max/Mad network transcription factors are known to govern target gene expression through recruiting histone acetyltransferases or deacetylases. In the present study, we show that Mad1 recruits the histone demethylase RBP2 to the Myc target telomerase reverse transcriptase (hTERT) gene promoter to repress transcription. With differentiation of leukemic HL60 cells, Mad1 and RBP2 were both up-regulated, interacted, and cooccupied the hTERT promoter accompanied by histone H3-K4 demethylation. In immortalized p493-6 B cells, shutting down c-Myc led to the accumulation of Mad1 and RBP2 at hTERT promoter and diminished hTERT mRNA expression. When RBP2 was depleted, hTERT expression was significantly enhanced, coupled with dissociation of RBP2 with and increased H3-K4 methylation at the hTERT promoter in p493-6 cells. Moreover, RBP2 and Mad1 were present on the hTERT promoter in human fibroblasts having a silent hTERT gene, and RBP2 depletion resulted in gene derepression. Taken together, Mad1 recruits RBP2 to the hTERT promoter that, in turn, demethylates H3-K4, thereby contributing to a stable repression of the hTERT gene in normal or differentiated malignant cells. Our findings reveal a novel mechanism through which the Myc/Max/Mad network proteins control their target gene transcription and provide insights into mechanisms underlying telomerase silencing and activation.