Metal Coordination Complex Derived Fe7S8 Particles Embedded in N-doped Carbon Framework with Regulated Porous Structure Enabling High-Rate and Durable Sodium Storage.

Iron sulfides with high theoretical capacity confront the challenges of low rate capability and severe capacity fading for sodium storage, which are mainly caused by poor electron/ion transport kinetics and drastic volume fluctuations during cycling. Herein, to mitigate these obstacles, a multi-step synthetic tactic involving solvothermal, carbonization, and subsequent sulfurization is put forward for the construction of wire-like structure by confining Fe7S8 particles in porous N-doped carbon framework (denoted as Fe7S8/PNC) using zinc iron nitrilotriacetate as template. By partially substituting Fe3+ with Zn2+ in the metal coordination complex, the porous structure of coordination complex derived carbon framework can be regulated through pore structure engineering of Zn nanodroplets. The desired porous and robust core/shell structure can not only afford favorable electron/Na+ transport paths and additional active sites for Na+ storage, but also provide reinforced structural integrity of interior Fe7S8 particles by retarding the pulverization and buffering the mechanical stress against volume fluctuations. As anode for sodium-ion batteries, the optimal Fe7S8/PNC delivers a high reversible capacity (743 mAh g-1 at 0.1 A g-1), superior rate capability (553 mAh g-1 at 10 A g-1), and long-term cycling stability (602 mAh g-1 at 5 A g-1 with 98.5% retention after 1000 cycles).

Achieving High-Rate and Stable Sodium-Ion Storage by Constructing Okra-Like NiS2/FeS2@Multichannel Carbon Nanofibers.

Transition metal sulfides (TMSs) are considered as promising anode materials for sodium-ion batteries (SIBs) due to their high theoretical capacities. However, the relatively low electrical conductivity, large volume variation, and easy aggregation/pulverization of active materials seriously hinder their practical application. Herein, okra-like NiS2/FeS2 particles encapsulated in multichannel N-doped carbon nanofibers (NiS2/FeS2@MCNFs) are fabricated by a coprecipitation, electrospinning, and carbonization/sulfurization strategy. The combined advantages arising from the hollow multichannel structure in carbon skeleton and heterogeneous NiS2/FeS2 particles with rich interfaces can provide facile ion/electron transfer paths, ensure boosted reaction kinetics, and help maintain the structural integrity, thereby resulting in a high reversible capacity (457 mA h g-1 at 1 A g-1), excellent rate performance (350 mA h g-1 at 5 A g-1), and outstanding long-term cycling stability (93.5% retention after 1100 cycles). This work provides a facile and efficient synthetic strategy to develop TMS-based heterostructured anode materials with high-rate and stable sodium storage properties.

Spatially Confined Fe7S8 Nanoparticles Anchored on a Porous Nitrogen-Doped Carbon Nanosheet Skeleton for High-Rate and Durable Sodium Storage.

Iron sulfides are widely explored as anodes of sodium-ion batteries (SIBs) owing to high theoretical capacities and low cost, but their practical application is still impeded by poor rate capability and fast capacity decay. Herein, for the first time, we construct highly dispersed Fe7S8 nanoparticles anchored on a porous N-doped carbon nanosheet (CN) skeleton (denoted as Fe7S8/NC) with high conductivity and numerous active sites via facile ion adsorption and thermal evaporation combined procedures coupled with a gas sulfurization treatment. Nanoscale design coupled with a conductive carbon skeleton can simultaneously mitigate the above obstacles to obtain enhanced structural stability and faster electrode reaction kinetics. With the aid of density functional theory (DFT) calculations, the synergistic interaction between CNs and Fe7S8 can not only ensure enhanced Na+ adsorption ability but also promote the charge transfer kinetics of the Fe7S8/NC electrode. Accordingly, the designed Fe7S8/NC electrode exhibits remarkable electrochemical performance with superior high-rate capability (451.4 mAh g-1 at 6 A g-1) and excellent long-term cycling stability (508.5 mAh g-1 over 1000 cycles at 4 A g-1) due to effectively alleviated volumetric variation, accelerated charge transfer kinetics, and strengthened structural integrity. Our work provides a feasible and effective design strategy toward the low-cost and scalable production of high-performance metal sulfide anode materials for SIBs.

Effect of Cryptorchidism on the Histomorphometry, Proliferation, Apoptosis, and Autophagy in Boar Testes.

Spontaneous unilateral cryptorchid boars have one testis in the abdomen or inguinal canal, causing its temperature to be at or near the body temperature, which impairs spermatogenesis, although the histomorphometry and molecular mechanisms underlying this process remain unclear. The aim of the present study was to determine the histomorphometry, proliferation, apoptosis, and autophagy alterations in spermatogonia and Sertoli cells in unilateral cryptorchid, scrotal (contrascrotal), and preweaning piglet (preweaning) testes. Histomorphometrical analysis of cryptorchid testes showed that the seminiferous tubules contained only Sertoli cells and a few spermatogonia, but did not contain post-meiotic germ cells. The number of spermatogonia markedly decreased, and the number of Sertoli cells did not change remarkably in cryptorchid testes. TUNEL assay results showed that apoptosis signals were predominantly observed in spermatogonia. In cryptorchid and contrascrotal testes, proliferating cell nuclear antigen (PCNA) and LC3 were located in spermatogonia. The number of PCNA-positive, TUNEL-positive, and LC3-positive germ cells was low, and the protein and mRNA levels of PCNA and LC3 were significantly decreased in cryptorchid testes. Taken together, the number of Sertoli cells did not change remarkably, whereas the number of germ cells decreased in the cryptorchid testes, compared with that in the contrascrotal testes. Insufficient proliferation, excessive apoptosis, and autophagy were involved in the regulation of the decrease in spermatogonia in cryptorchid boar testes.

Expression and localization of meiosis-associated protein in gonads of female rats at different stages.

It was well known that a critical process of oogenesis in the female mammalian was the entry of mitotic oogonia into meiosis. Early studies from model animal mice suggested that the retinoic acid (RA) response signal protein STRA8 (stimulated by retinoic acid gene 8) and the meiosis-specific chromosomal behavior marker protein SCP3 (Synaptonemal Complex Protein 3) were two crucial molecular markers during meiosis. The expression of STRA8 and SCP3 at different stages in rat ovaries was investigated by immunohistochemistry, qRT-PCR and Western Blot. Immunohistochemistry results showed that STRA8 and SCP3 were mainly expressed in embryonic stage. And STRA8 was expressed in the cytoplasm and nucleus of the ovaries after birth. qRT-PCR and Western Blot results showed that the mRNA and protein levels of STRA8 and SCP3 were expressed in embryonic stage. The expression of STRA8 and SCP3 indicated germ cells enter meiosis in rats embryo, and STRA8 and SCP3 could serve as molecular markers for the meiosis in rats. The localization of STRA8 in the nucleus increased the possibility that STRA8 might act as transcription factor or activate transcription to function after birth.

Effects of body temperature on the expression and localization of meiosis-related proteins STRA8 and SCP3 in boar testes.

Body temperature could lead to interruption of spermatogenesis, but the molecular mechanism was still unclear. Cryptorchidism was defined as the failure of testes to enter the scrotum, which exposed the testes to body temperature. Meiosis was a unique feature of germ cell development. Whether cryptorchidism damage the initiation of meiosis in boars had not been reported. The aim of this study was to determine whether spermatogonia in the cryptorchid testes entered into meiosis by detecting meiosis-related markers stimulated by retinoic acid gene 8 (STRA8) and synaptonemal complex protein 3 (SCP3). Three boars with spontaneous unilateral abdominal cryptorchidism were used. The testis located in the abdomen was cryptorchidism group, the scrotal testis of the same animal was used as control. HE results showed that only Sertoli cells, and a few spermatogonia remained in the seminiferous tubules, and no spermatids were seen compared with the control. Immunohistochemistry results showed that in both control and cryptorchidism group, STRA8 was mainly expressed in the nucleus of spermatogonia and spermatocytes. In control group, SCP3 was expressed in the nucleus of spermatocytes. In cryptorchidism group, SCP3 immunopositive cells were also observed. qRT-PCR and Western Blot results showed that the mRNA and protein levels of STRA8 and SCP3 were significantly decreased in cryptorchid boars. The expression of STRA8 and SCP3 in cryptorchidism suggested that spermatogonia could still enter meiosis in cryptorchid boars.