Characterization,expression dynamics,and potential function of OPA1 for regulation of mitochondrial morphology during spermiogenesis in Phascolosoma esculenta

Mitochondria undergo morphological changes during spermatogenesis in some animals.The mechanism and role of mitochondrial morphology regulation,however,remain somewhat unclear.In this study,we analyzed the molecular characteristics,expression dynamics and subcellular localization of optic atrophy protein 1(OPA1),a mitochondrial fusion and cristae maintenance-related protein,to reveal the possible regulatory mechanisms underlying mitochondrial morphology in Phascolosoma esculenta spermiogenesis.The full-length cDNA of the P.esculenta opa1 gene(Pe-opa1)is 3743 bp in length and encodes 975 amino acids.The Pe-OPA1 protein is highly conservative and includes a transmembrane domain,a GTPase domain,two helical bundle domains,and a lipid-interacting stalk.Gene and protein expression was higher in the coelomic fluid(a site of spermatid development)of male P.esculenta and increased first and then decreased from March to December.Moreover,their expression during the breeding stage was significantly higher than during the non-breeding stage,suggesting that Pe-OPA1 is involved in P.esculenta reproduction.The Pe-OPA1 protein was more abundant in components consisting of many spermatids than in components without,indicating that Pe-OPA1 mainly plays a role in the spermatid in coelomic fluid.Moreover,Pe-OPA1 was mainly detected in the spermatid mitochondria.Immunofluorescence experiments showed that the Pe-OPA1 are constitutively expressed and co-localized with mitochondria during spermiogenesis,suggesting its involvement in P.esculenta spermiogenesis.These results provide evidence for Pe-OPA1's involvement in the regulation of mitochondrial morphology during spermiogenesis.

燃料电池多孔碳载体高石墨化的超快速碳热冲击策略

质子交换膜燃料电池(PEMFC)具有能源转换效率高、清洁环保等优点,是新能源技术的重要发展方向.目前,燃料电池中主要使用的电催化剂是碳载铂或铂合金,碳载体不仅增强催化剂活性,提高贵金属利用率,而且对催化剂的耐久性起着至关重要的影响.但常规的碳载体在燃料电池强腐蚀环境中容易发生腐蚀,进而导致催化剂颗粒脱落和团聚,活性衰减.近年来,研究发现提高碳载体石墨化程度有利于增强载体的耐腐蚀能力,提高催化剂的稳定性.常规的高温热处理难以大幅提高载体的石墨化,且长时间的高温处理易导致原始碳结构的坍塌或转变以及比表面积显著下降.因此,迫切需要发展新的策略或技术经济、高效地提高碳载体的石墨化度,并且保持碳载体原始结构和形貌.本文提出了一种快速且低成本的碳热冲击方法,用于多孔碳材料的石墨化处理,包括碗状碳(BC)、空心碳球、ZIF-8衍生碳和商业炭黑等.其中,以碗状碳为研究对象,即将碗状碳载体与石墨化催化剂氯化铁通过超声共混,干燥后放入加热源碳毡中,通过快速碳热冲击,3 s内升温至1300℃,在该温度保温30 s后,3 s降至室温,最后酸洗得到高石墨化碗状碳.作为对照,含有氯化铁的碗状碳也在普通管式炉中石墨化处理.采用X射线衍射(XRD)、Raman光谱、四探针电导率测试、氮气吸脱附曲线、扫描电镜(SEM)和透射电镜等表征手段对所得的石墨化碗状碳进行表征.同时,以碳热冲击所得的高石墨化碗状碳为载体合成了碳载的Pt Co金属间化合物催化剂(PtCo/G-BC-S),并通过旋转圆盘电极及单电池考察其电催化性能.XRD、Raman光谱、电导率测试和SEM结果表明,碳热冲击处理后的碗状碳具有高的石墨化程度,其电导率高达5.7 S cm^(–2)(20 MPa下),为原始碗状碳的7倍,同时依然维持原有碗状结构.而对于普通管式炉煅烧后的碗状碳,虽然石墨化程度得到提高,但其结构出现了严重的坍塌,且比表面积下降严重.电化学测试结果表明,PtCo/G-BC-S表现出较好的ORR催化性能,在高电位(1.0–1.5 V)下G-BC-S具有高的耐腐蚀性能:PtCo/G-BC-S的半波电位(0.933 V)均高于Pt Co/BC(0.928 V)和商业Pt/C(0.89 V).此外,高电位下的加速耐久性测试结果表明,PtCo/G-BC-S的半波电位只衰减了13 mV,而PtCo/BC和商业Pt/C分别衰减了22 mV和47 mV.以上研究结果表明,PtCo/G-BC-S催化剂的高活性和稳定性来自于两个方面:铂钴金属间化合物催化剂的高活性和化学/结构稳定性,以及碗状碳载体的高石墨化度和多孔结构.提高碳载体的耐久性对燃料电池的稳定性至关重要,其中通过提高石墨化来缓解碳腐蚀是重要方法之一.综上,本文为制备高耐久性碳载体提供了一种高效、经济的策略,对推动燃料电池的发展具有借鉴意义.

Ce-modified AlZr pillared clays supported-transition metals for catalytic combustion of chlorobenzene

In this article, we provided a one-step hydrothermal method to prepare composite AIZr pillaring agents, and synthesized AlZr-pillared clays （AIZr-PILC） via ion exchange. Compared with conventional methods, our method successfully shortened synthetic routes and greatly reduced consumption of the materials. Then, A1Zr-PILC-supported manganese and cerium oxide catalysts were obtained by impregnation method. The compositions and properties of these catalysts were characterized by some technical means. The energy dispersive X-ray spectroscopy clearly shows the existence of Mn, Ce, and O, which indicates the successful loading of the active components on the surface of AIZr-PILC. Meanwhile, the results of X- ray diffraction （XRD） and N2 adsorption experiments demonstrate that the synthesized A1Zr-PILC out- performs the raw clays （Na-mmt） and mononuclear AI-PILC in the catalytic combustion of chloroben- zene. XRD and high-resolution transmission electron microscopy also proves that the high activity of them is related to the high dispersion of the oxides and the exposure of more active sites. H2-temper- ature-programmed reduction shows that cerium can promote the redox cycles of the manganese system through the strong interactions between MnO2, CeO2 and AIZr-PILC. In particular, MnCe（9：1 ）/AIZr-PILC shows the best catalytic activity in the catalytic combustion of chlorobenzene.

PdZn intermetallic compound stabilized on ZnO/nitrogendecorated carbon hollow spheres for catalytic semihydrogenation of alkynols

Enhancing the selectivity of noble metal catalysts through electronic modulation is important for academic research and chemical industrial processes.Herein,we report a facile sacrificial template strategy for the synthesis of PdZn intermetallic compound(3-4 nm)highly distributed in ZnO/nitrogen-decorated carbon hollow spheres(PdZn-ZnO/NCHS)to optimize the selectivity of Pd catalysts,which involves carbonization of a core-shell structured polystyrene(PS)@ZIF-8 precursor in an inert atmosphere,impregnation Pd precursor,and subsequent H2 reduction treatment.Due to the unique structural and compositional features,the developed PdZn-ZnO/NCHS delivers an excellent catalytic performance for the semihydrogenation of 2-methyl-3-butyn-2-ol(MBY)to 2-methyl-3-buten-2-ol(MBE)with high activity(>99%),high selectivity(96%),and good recyclability,outperforming the analog Pd on ZnO(Pd/ZnO)as well as the supported Pd nanoparticles(Pd/C and Pd/NC).Density functional theory(DFT)calculations reveal that the presence of Znδ+species in PdZn-ZnO/NCHS alters the adsorption modes of reactant and product,leading to a decrease of the adsorption strength and an enhancement of the energy barrier for overhydrogenation,which results in a kinetic favor for the selective transformation of MBY to MBE.In addition,PdZn-ZnO/NCHS was also very effective for the partial hydrogenation of dehydrolinalool to hydrolinalool.

Construction of isolated Ni sites on nitrogen-doped hollow carbon spheres with Ni-N_(3) configuration for enhanced reduction of nitroarenes

Designing and synthesizing high-efficiency non-precious metal-based catalysts having uniform active sites increases the reactivity and selectivity of materials and provides a platform for an in-depth understanding of their catalytic reaction mechanism.In this study,we provided an approach for fabricating isolated nickel single-atom sites(Ni SAs)with high loading(4.9 wt.%)stabilized on nitrogen-doped hollow carbon spheres(NHCS)using a core–shell structured Zn/Ni bimetallic zeolitic imidazolate framework(ZIF)composite as the sacrificial template.The as-fabricated Ni SAs/NHCS catalyst shows superior activity,selectivity,and recycling durability for the catalytic transfer hydrogenation of nitrobenzene to aniline,thus achieving 100%yield of aniline with a turn-over frequency(TOF)value as high as 29.9 h^(−1) under mild conditions.This TOF value is considerably superior to the supported Ni nanoparticle catalysts.The experiments designed show that the hollow structure feature of NHCS facilitates accessible active sites and mass transfer,which thus contributes to the enhancement of the catalytic performance of Ni SAs/NHCS.Density functional theory calculations show the high chemo-selectivity and activity of the Ni SAs catalyst,arising from the unique role of the single Ni-N3 site on simultaneously activating the H donor(N_(2)H_(4))and substrate,as well as the hydrogenation of the–NOH group as the rate-determining step.