[Retrospective study on the impact of penile corpus cavernosum injection test on penile vascular function].

OBJECTIVE: To investigate the impact of age, various hormonal levels, and biochemical markers on penile cavernous body vascular function in patients with erectile dysfunction (ED). Me-thods: A retrospective analysis of clinical data from male patients with ED who underwent color duplex Doppler ultrasonography (CDDU) and intracavernosal injection test (ICI) at the Reproductive Medicine Center of Peking University Third Hospital from January 2020 to August 2023. Data were managed and processed using SPSS 29.0, and a multivariable Logistic regression analysis was conducted. RESULTS: A total of 700 ED patients were included, with 380 showing negative ICI results and 320 positive. In the study, 84 patients had a peak systolic velocity (PSV) < 25 cm/s, while 616 had PSV≥25 cm/s; 202 patients had end-diastolic velocity (EDV)>5 cm/s, and 498 had EDV≤5 cm/s. 264 patients had abnormal PSV and/or EDV results, and 436 had normal results for both. Patients with vascular ED had significantly lower estrogen levels (t=-3.546, P < 0.001), lower testosterone levels (t=-2.089, P=0.037), and a higher rate of hyperglycemia (χ2=12.772, P=0.002) compared with those with non-vascular ED. The patients with arterial ED were older (t=3.953, P < 0.001), had a higher rate of hyperglycemia (χ2=9.518, P=0.009), and a higher estrogen/testosterone ratio (t=2.330, P=0.020) compared with those with non-arterial ED. The patients with mixed arteriovenous ED had higher age (t=3.567, P < 0.001), lower testosterone levels (t=-2.288, P=0.022), a higher rate of hyperglycemia (χ2=12.877, P=0.002), and a larger estrogen/testosterone ratio (t=2.096, P=0.037) compared with those with normal findings. Multifactorial Logistic regression analysis indicated that higher levels of estrogen were a protective factor for vascular ED (OR=1.009, 95%CI: 1.004-1.014), and glucose≥7.0 mmol/L was a risk factor (OR=0.381, 95%CI: 0.219-0.661). Older age was a risk factor for arterial ED (OR=0.960, 95%CI: 0.938-0.982). Additionally, older age (OR=0.976, 95%CI: 0.958-0.993) and glucose levels of 5.6-6.9 mmol/L (OR=0.591, 95%CI: 0.399-0.876) were also risk factors for mixed arterio-venous ED. CONCLUSION: Hyperglycemia and aging may impair penile cavernous body vascular function, while higher levels of estrogen may have a protective effect on it.

Micro-TESE strategy in patients with NOA caused by AZFc deletion: synchronous or asynchronous?

In the treatment of infertile patients with non-obstructive azoospermia (NOA) caused by the deletion of the azoospermia factor c region (AZFc) on the Y chromosome, synchronous and asynchronous surgical strategies are discussed. Clinical data from NOA patients with the AZFc deletion who underwent micro-TESE were analyzed retrospectively. The sperm retrieval rate (SRR) and sperm utilization rate of synchronous and asynchronous operation groups were followed up and compared. The fertilization rate, high-quality embryo rate, clinical pregnancy rate, abortion rate, and cumulative live birth rate of ICSI in patients with successful sperm retrieval were compared between the two groups. The two groups had sperm utilization rates of 98.9% (93/94) and 50.0% (14/28), respectively. The asynchronous group's sperm consumption rates were much lower than those of the synchronous operation group. Fertilization rate, high-quality embryo rate, clinical pregnancy rate of fresh transfer cycle, abortion rate, and cumulative live birth rate of patients in the synchronous operation group with fresh sperm, and the asynchronous operation group with thawed sperm, respectively, were 30.6% vs 33.8%, 33.8% vs 40.7%, 40.0% vs 12.5%, 30.4% vs 7.1%. Between the two groups, there was no significant difference. This suggests that individuals with NOA caused by the AZFc deletion have a high possibility of successfully acquiring sperm using micro-TESE and ICSI to conceive their own offspring. Synchronous micro-TESE is recommended to improve sperm utilization rate and the cumulative live birth rate.

Construction of dual active sites for efficient alkaline hydrogen evolution: single-metal-atoms supported on BC2N monolayers.

Electrocatalytic water splitting suffers from sluggish kinetics towards the hydrogen evolution reaction (HER). Balancing the adsorption/desorption ability towards H* and OH* is considered to be an efficient way to enhance the HER efficiency, but it is too hard at one activity site. In this work, the HER activity of the single 3d transition metal atom-anchored BC2N monolayer (M@BC2N, M = Fe, Co, and Ni) was investigated by a density functional theory approach. Our calculation suggests that an efficient dual-active site is formed on M@BC2N towards the HER, i.e., the metal center M as the OH* active site and its adjacent C atoms as the H* active site. The combination of single M atoms with the BC2N monolayer can effectively tune the electronic structure of dual active sites to optimize the adsorption of H* and OH*, resulting in a HER activity sequence of Fe@BC2N < Co@BC2N < Ni@BC2N. Notably, the HER exchange current density of Ni@BC2N reaches up to 0.53 mA cm-2, which is close to the value for commercial Pt/C, suggesting its huge potential in the HER.

Polycyclic Aromatic Hydrocarbons as a New Class of Promising Cathode Materials for Aluminum-Ion Batteries.

As an emerging post-lithium battery technology, aluminum ion batteries (AIBs) have the advantages of large Al reserves and high safety, and have great potential to be applied to power grid energy storage. But current graphite cathode materials are limited in charge storage capacity due to the formation of stage-4 graphite-intercalated compounds (GICs) in the fully charged state. Herein, we propose a new type of cathode materials for AIBs, namely polycyclic aromatic hydrocarbons (PAHs), which resemble graphite in terms of the large conjugated π bond, but do not form GICs in the charge process. Quantum chemistry calculations show that PAHs can bind AlCl4 - through the interaction between the conjugated π bond in the PAHs and AlCl4 - , forming on-plane interactions. The theoretical specific capacity of PAHs is negatively correlated with the number of benzene rings in the PAHs. Then, under the guidance of theoretical calculations, anthracene, a three-ring PAH, was evaluated as a cathode material for AIBs. Electrochemical measurements show that anthracene has a high specific capacity of 157 mAh g-1 (at 100 mA g-1 ) and still maintains a specific capacity of 130 mAh g-1 after 800 cycles. This work provides a feasible "theory guides practice" research model for the development of energy storage materials, and also provides a new class of promising cathode materials for AIBs.

Boosting the Cycling Stability of Aqueous Flexible Zn Batteries via F Doping in Nickel-Cobalt Carbonate Hydroxide Cathode.

Cathodes of rechargeable Zn batteries typically face the issues of irreversible phase transformation, structure collapse, and volume expansion during repeated charge/discharge cycles, which result in an increased transfer resistance and poor long-term cycling stability. Herein, a facile F doping strategy is developed to boost the cycling stability of nickel cobalt carbonate hydroxide (NiCo-CH) cathode. Benefiting from the extremely high electronegativity, the phase and morphology stabilities as well as the electrical conductivity of NiCo-CH are remarkably enhanced by F incorporation (NiCo-CH-F). Phase interface and amorphous microdomains are also introduced, which are favorable for the electrochemical performance of cathode. Benefiting from these features, NiCo-CH-F delivers a high capacity (245 mA h g-1 ), excellent rate capability (64% retention at 8 A g-1 ), and outstanding cycling stability (maintains 90% after 10 000 cycles). Moreover, the quasi-solid-state battery also manifests superior cycling stability (maintains 90% after 7200 cycles) and desirable flexibility. This work offers a general strategy to boost the cycling stability of cathode materials for aqueous Zn batteries.

DJ-1 deficiency causes metabolic abnormality in ornidazole-induced asthenozoospermia.

Asthenozoospermia (AS), defined as low-motility spermatozoa in the ejaculate, is a frequent cause of human male infertility. DJ-1 (also known as PARK7), a protein highly associated with male sterility, binds to the mitochondrial complex I subunit to protect mitochondrial function. However, its involvement in spermatogenesis has not been fully elucidated. Previously, the levels of DJ-1 were shown to be significantly decreased in testicular tissues of rats with ornidazole (ORN)-induced AS. Here, we used a rat model to investigate the localization and expression levels of DJ-1 and its interacting NDUFS3 and NDUFA4 mitochondrial complex I subunits, as well as AS-induced metabolic alterations in testicular tissues. ORN significantly reduced the levels of DJ-1 in the nucleus of secondary spermatocytes, while increasing the expression of NDUFS3 in the cytoplasm of primary spermatocytes. Further, NDUFA4 showed higher expression after treatment with ORN. The principal ORN-induced changes in metabolic small molecules related to the accumulation of glucose, glutamine, and N-acetyl aspartate, enhancement of purine pathway, increase of the phosphatidic acid (PA) (18:0/18:1), phosphatidylethanolamine (PE) (16:0/18:1), and PA (18:0/20:4) lipid metabolites, and imbalance in the concentrations of Na+ and K+. However, we did not observe any abnormalities of certain small metabolic molecules and metal ions in semen samples from patients with AS. In conclusion, these results suggest that DJ-1 deficiency in testicular tissues might be closely related to the localization of NDUFS3 and content of NDUFA4, thus causing abnormalities in the mitochondrial energy metabolism and multiple other metabolic pathways.

Sexual life and medication taking behaviours in young men: An online survey of 92 620 respondents in China.

OBJECTIVES: To assess sexual life and medication taking behaviours in young Chinese men. METHODS: An online survey was conducted across China between January 2017 and April 2017. Among the participants, men aged 19-40 years were included in the analysis. The respondents filled in the online questionnaire assessing sexual life and medication taking behaviours by themselves, including general information, cognition of erectile dysfunction (ED) and treatment-related questions. Erection hardness score (EHS) was used to measure the erection hardness status. RESULTS: Among the young respondents, 20.54% had grade I-II EHS, 58.14% searched the internet for online ED-related information, 26.49% took an ED medication and 50.89% took an ED medication without the advice of a physician or pharmacist. The respondents who took medication had less sexual intercourse per week (P < .001) and worse EHS (P < .001), and were more willing to seek information from physicians, pharmacists, friends and relatives instead of online sources (P < .001), compared with those not taking medication. The most common comorbidities in patients with grade I-II EHS were hyperlipidaemia, cardiovascular disease (CVD), prostate diseases and diabetes mellitus. CONCLUSION: About 20% of young Chinese men needed further assessment for ED. The majority of respondents obtained ED-related information by online search and took an ED medication without professional advice. These data could help clinicians understand the current status of sexual life and medication taking behaviours of young Chinese men.

Altered gene expression profiles of testicular tissues from azoospermic patients with maturation arrest.

Maturation arrest is a common cause of male infertility which has caused worldwide concern, and its pathophysiological process remains further elucidation. Our study aimed to identify genetic characteristics of maturation arrest by comparing gene expression between maturation arrest and normal samples using microarray technology. A total of 6,373 genes were identified differentially expressed (p < .05, fold change > 2.0 or <-2.0) and 1,594 genes were selected as statistically significant after Bonferroni correction, including 419 up-regulated and 1,175 down-regulated genes. Microarray data were validated by quantitative reverse transcriptase-polymerase chain reaction. Bioinformation analysis was performed to explore genetic function of statistically significant genes. Gene Ontology results showed the statistically significant genes enriched in sexual reproduction, spermatogenesis and male gamete generation. Reactome pathway analysis highlighted the olfactory signalling pathway, fertilisation, developmental biology, etc. One module and eight hub genes were found to be involved in ubiquitin-mediated proteolysis and may affect as indicators of spermatogenic process through protein-protein interaction analysis. Our study provided a comprehensive genetic characteristic of differential expressed genes in testicular tissues from maturation arrest patients and speculated several genes as potential indicators of disease.

Spatial distribution and determinants of PM2.5 in China's cities: fresh evidence from IDW and GWR.

While numerous studies have explored the spatial patterns and underlying causes of PM2.5 at the urban scale, little attention has been paid to the spatial heterogeneity affecting PM2.5 factors. In order to enrich this research field, we collected PM2.5 monitoring data from 367 cities across China in 2016 and combined inverse distance weighted interpolation (IDW) and geographically weighted regression (GWR) model. As a result, we could dynamically describe the spatial distribution pattern of urban PM2.5 at monthly, seasonal, and annual scales and investigate the spatial heterogeneity of the influential factors on urban PM2.5. Furthermore, in order to make the result more scientific and reasonable, the paper used selection.gwr function and bw.gwr function, respectively, to optimize model, thereby avoiding local collinearity caused by independent variables. The main results are as follows: (1) PM2.5 in Chinese cities is characterized as time-space non-equilibrium pattern. The Beijing-Tianjin-Hebei region, the Yangtze River corner region, the Pearl River Delta region, and the northeast region have formed a pollution-concentrating core area with Beijing-Tianjin-Hebei region as the axis, which brings greater difficulties and challenges to PM2.5 governance. (2) The effects of various factors of socio-economic activities on the concentration of PM2.5 have significant spatial heterogeneity among Chinese cities. (3) There is an inverted "U" curve between economic growth and PM2.5. When the per capita income reaches 47,000 yuan, the PM2.5 emission reaches the peak, which proves the existence of environmental Kuznets curve (EKC). These findings could provide a significant reference for policy makers in China to facilitate targeted and differentiated regional PM2.5 governance measures.

Insight into thiophene hydrodesulfurization on clean and S-modified MoP(010): a periodic density functional theory study.

The hydrodesulfurization (HDS) of thiophene on clean and S-modified MoP(010) is investigated to understand the HDS mechanism as well as the surface sulfur (S) atom effect using periodic density functional theory (DFT). The results show that thiophene prefers strongly flat adsorption on both the clean and S-modified surfaces, in either the molecular state or the dissociative state breaking simultaneously one C-S bond, and the adsorption of thiophene can be slightly weakened by the surface S atom. Thermodynamic and kinetic analysis indicates that the HDS of thiophene in both the molecular and dissociative adsorption states prefers to take place along the direct desulfurization (DDS) pathway rather than hydrogenation on both the clean and S-modified MoP(010) surfaces. Surface S shows a promotion effect on the HDS catalytic activity of MoP(010), because the energy barrier/rate constant of the rate-determining step on the DDS pathway is decreased/enlarged under the S modification. Compared with the situation of MoP(001), MoP(010) should have relatively low HDS activity, since a higher energy barrier as well as weaker exothermicity is involved in the reaction on the latter surface.

Sodium-Hydrogen-Exchanger expression in human sperm and its relationship with semen parameters.

PURPOSE: Sperm-specific sodium-hydrogen exchanger (sNHE) is essential to maintain sperm normal function in mice; however, its role in human sperm has not been clarified to date. The aim of this study is to investigate the expression pattern of sNHE in human spermatozoa and its relationship with sperm functional parameters. METHOD: Semen samples from 68 asthenozoospermic and 61 normozoospermic men were analyzed for sperm concentration, motility, and acrosome reaction, and high motile spermatozoa were collected by swim-up method. The expression of sNHE in spermatozoa was detected by Western blot and immunofluorescence staining. The relationship between sNHE expression and sperm parameters was assessed. RESULTS: We identified sNHE is mainly localized to the principal piece of the human sperm tail. The expression of sNHE was positively correlated with sperm concentration, total number, and progressive motility. Moreover, sNHE expression was upregulated in swim-up sperm and associated with most of sperm motility parameters including straight line velocity and curvilinear velocity. Our results also showed that sNHE expression is decreased in sperm from patients with asthenozoospermia compared with that from normal controls. However, no correlation was found between sNHE expression and acrosome reaction in spermatozoa. CONCLUSIONS: The expression pattern of sNHE suggested that this protein may be involved in the regulation of sperm motility, and aberration of its expression in sperm may contribute to the pathogenesis of asthenozoospermia.

[Microdissection testicular sperm extraction for patients with nonmosaic Klinefelter syndrome: A report of 143 cases].

OBJECTIVE: To investigate the clinical application and outcomes of microdissection testicular sperm extraction (micro-TESE) in patients with nonmosaic Klinefelter syndrome (KS). METHODS: A total of 143 nonmosaic KS patients underwent micro-TESE in the Center of Reproductive Medicine of Peking University Third Hospital between July 2012 and August 2016. We analyzed their clinical and follow-up data and evaluated the outcomes. RESULTS: Spermatozoa were successfully retrieved from the testicular tissue in 44.76% (64/143) of the patients, 84.4% (54/64) by unilateral and 15.6% (10/64) by bilateral micro-TESE. Seventy-five of the KS patients were followed up in the years of 2014 and 2015. Of the 34 patients with successful sperm retrieval, 73.52% (25/34) achieved clinical pregnancy and 8 boys and 8 girls were already born in 14 of the 25 cases. CONCLUSIONS: The micro-TESE is a useful method for sperm retrieval in nonmosaic KS patients, with high rates of sperm retrieval, clinical pregnancy, and birth of biological offspring.

[Impact of the CFTR chloride channel on the cytoskeleton of mouse Sertoli cells].

OBJECTIVE: To study the impact of the chloride channel dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) on the cytoskeleton of Sertoli cells in the mouse. METHODS: TM4 Sertoli cells were cultured and treated with CFTR(inh)-172 at the concentrations of 1, 5, 10 and 20 µmol/L for 48 hours. Then the cytotoxicity of CFT(inh)-172 was assessed by CCK-8 assay, the expressions of F-actin and Ac-tub in the TM4 Sertoli cells detected by immunofluorescence assay, and those of N-cadherin, vimentin and vinculin determined by qPCR. RESULTS: CFTR(inh)-172 produced cytotoxicity to the TM4 Sertoli cells at the concentration of 20 µmol/L. The expressions of F-actin and Ac-tub were decreased gradually in the TM4 Sertoli cells with the prolonging of treatment time and increasing concentration of CFTR(inh)-172 (P < 0.05). The results of qPCR showed that different concentrations of CFTR(inh)-172 worked no significant influence on the mRNA expressions of N-cadherin, vimentin and vinculin in the Sertoli cells. CONCLUSION: The CFTR chloride channel plays an important role in maintaining the normal cytoskeleton of Sertoli cells. The reduced function and expression of the CFTR chloride channel may affect the function of Sertoli cells and consequently spermatogenesis of the testis.

Theoretical Investigation of the Methanol Decomposition by Fe+)and Fe(C2H4)+: A π-Type Ligand Effect.

Density functional theory has been used to probe the mechanism of gas-phase methanol decomposition by bare Fe(+) and ligated Fe(C(2)H(4))(+) in both quartet and sextet states. For the Fe(+)/methanol system, Fe(+) could directly attach to the O and methyl-H atoms of methanol, respectively, forming two encounter isomers. The methanol reaction with Fe(+) prefers initial C-O bond activation to yield methyl with slight endothermicity, whereas CH(4) elimination is hindered by the strong endothermicity and high-energy barrier of hydroxyl-H shift. For the Fe(C(2)H(4))(+)/methanol system, the major product of H(2)O is formed through six elementary steps: encounter complexation, C-O bond activation, C-C coupling, ß-H shift, hydride H shift, and nonreactive dissociation. Both ligand exchange and initial C-O bond activation mechanisms could account for ethylene elimination with the ion products Fe(CH(3)OH)(+) and (CH(3))Fe(OH)(+), respectively. With the assistance of a π-type C(2)H(4) ligand, the metal center in the Fe(C(2)H(4))(+)/CH(3)OH system avoids formation of unfavorable multi-σ-type bonding and thus greatly enhances the reactivity compared to that of bare Fe(+).

Evaluation of syphilis serostatus on the safety of IVF treatment.

An increasing number of infertile syphilis-infected individuals have turned to assisted reproductive technology; however, the safety of syphilis carrier serostatus on IVF and embryo transfer outcomes has not been evaluated. Data from 482 patients who delivered singletons were analysed. In the retrospective study, the rate of IVF and intracytoplasmic sperm injection fertilization was 79.50% ± 17.57%/78.72% ± 16.66% in the Treponema pallidum particle agglutination assay negative (TPPA-negative) and rapid plasma reagin negative (RPR-negative) group, 76.12% ± 22.99%/74.05% ± 20.31% in the TPPA-positive and RPR-negative group, and 75.66% ± 21.72%/70.90% ± 16.11% in the TPPA-positive and RPR-positive group. The clinical pregnancy rate was 39.79% in the TPPA-negative and RPR-negative group, 46.30% in the TPPA-positive and RPR-negative group, and 36.59% in the TPPA-positive and RPR-positive group. No significant differences were found between the groups. The neonatal gestational age and mean birth weight were not significantly different between the TPPA-negative and TPPA-positive groups. Multiple linear regression analysis also showed no association between TPPA serostatus and newborn birth weight and gestational age. The present retrospective study showed that TPPA and RPR serostatus did not affect the outcomes of IVF and embryo transfer. Syphilis-infected individuals can undergo IVF and embryo transfer cycles after penicillin treatment.

[Yimusake Tablet: safe and efficacious for premature ejaculation].

OBJECTIVE: To objectively evaluate the efficacy and safety of Yimusake Tablet in the treatment of premature ejaculation (PE) through a multi-centered large-sample trial. METHODS: We conducted a multi-centered, open, fixed-dose, and self-compared clinical trial among 300 patients with diagnosed PE. The trial lasted 12 weeks, including 4 weeks without any medication and 8 weeks of treatment with Yimusake Tablet, 2 pills (1 g) per night. We observed the intravaginal ejaculation latency time (IELT) before and after treatment, evaluated the safety of medication, and performed a questionnaire investigation on the patients' satisfaction. RESULTS: Of the 300 PE patients, 288 accomplished the clinical trial. The patients ranged in age from 22 to 60 years, averaging at 31.6 years. The mean IELT of the patient was 62.5 seconds at baseline, 168.9 seconds after 4 weeks of treatment with Yimusake Tablet, and 222.2 seconds after 8 weeks of medication. Among the 157 patients with normal erectile function (IIEF >21), the mean IELT was 71.4 seconds before treatment, 147.4 seconds after 4 weeks of medication, and 172.5 seconds after 8 weeks of medication. The patients' satisfaction was significantly increased after treatment. Those complicated by mild to moderate erectile dysfunction achieved different degrees of improvement in the IIEF-5 score, with a mean increase of 3.8. Only a few patients experienced mild adverse events, including constipation, dry mouth, nose bleeding, abdominal pain, and lumbosacral pain, which were all relieved without drug withdrawal. CONCLUSION: Yimusake Tablet is a safe and effective medicine for the treatment of PE.

[Microsurgical management of male infertility in china: 15-year development and prospects].

Male infertility is a common and complex disease in urology and andrology, and for many years there has been no effective surgical treatment. With the emergence of microsurgery and assisted reproductive medicine (IVF/ICSI), rapid development has been achieved in the treatment of male infertility. The Center for Male Reproductive Medicine and Microsurgery at Weill Cornell Medical College of Cornell University has been playing an important leading role in developing microsurgical techniques for the management of male infertility. The development of microsurgical treatment of male infertility in China has experienced the 3 periods of emerging, making, and boosting ever since its systematic introduction from Weill Cornell Medical College 15 years ago. At present, many Chinese hospitals have adopted microsurgery in the management of male infertility, which has contributed to the initial establishment of a microsurgical treatment system for male infertility in China. However, some deficiencies do exist concerning microsurgical treatment of male infertility, as in normalized technical training programs for competent surgeons, unified criteria for evaluation of surgical outcomes, and detailed postoperative follow-up data. This article presents an overview on the 15-year development of microsurgical management of male infertility in China, points out the existing deficiencies, and offers some propositions for the promotion of its development.

First Principles Study of the Structure-Performance Relation of Pristine Wn+1Cn and Oxygen-Functionalized Wn+1CnO2 MXenes as Cathode Catalysts for Li-O2 Batteries.

Li-O2 batteries are considered a highly promising energy storage solution. However, their practical implementation is hindered by the sluggish kinetics of the oxygen reduction (ORR) and oxygen evolution (OER) reactions at cathodes during discharging and charging, respectively. In this work, we investigated the catalytic performance of Wn+1Cn and Wn+1CnO2 MXenes (n = 1, 2, and 3) as cathodes for Li-O2 batteries using first principles calculations. Both Wn+1Cn and Wn+1CnO2 MXenes show high conductivity, and their conductivity is further enhanced with increasing atomic layers, as reflected by the elevated density of states at the Fermi level. The oxygen functionalization can change the electronic properties of WC MXenes from the electrophilic W surface of Wn+1Cn to the nucleophilic O surface of Wn+1CnO2, which is beneficial for the activation of the Li-O bond, and thus promotes the Li+ deintercalation during the charge-discharge process. On both Wn+1Cn and Wn+1CnO2, the rate-determining step (RDS) of ORR is the formation of the (Li2O)2* product, while the RDS of OER is the LiO2* decomposition. The overpotentials of ORR and OER are positively linearly correlated with the adsorption energy of the RDS LixO2* intermediates. By lowering the energy band center, the oxygen functionalization and increasing atomic layers can effectively reduce the adsorption strength of the LixO2* intermediates, thereby reducing the ORR and OER overpotentials. The W4C3O2 MXene shows immense potential as a cathode catalyst for Li-O2 batteries due to its outstanding conductivity and super-low ORR, OER, and total overpotentials (0.25, 0.38, and 0.63 V).

Theoretical Study of Catalytic Performance of Pristine M2C and Oxygen-Functionalized M2CO2 MXenes as Cathodes for Li-N2 Batteries.

Li-N2 batteries are a promising platform for electrochemical energy storage, but their performance is limited by the low activity of the cathode catalysts. In this work, density functional theory was used to study the catalytic activity of the pristine M2C and oxygen-functionalized M2CO2 MXenes (M = Sc, Ti, and V) as cathodes for Li-N2 batteries. The calculated results suggest that the pristine M2C MXenes (M = Sc, Ti, and V) show high electrical conductivity due to the Fermi level crossing the metal 3d states. The stable adsorption of N2 occurs on M2C MXenes via a side-on model and strengthens gradually with decreasing metal atomic number. Furthermore, the kinetics of N2 dissociation can be significantly accelerated by the coadsorption of Li on M2C MXenes. However, adsorption and dissociation of N2 on the M2CO2 surfaces are too difficult to occur due to strong electrostatic repulsion. The Li-mediated nitrogen reduction reaction during discharge proceeds favorably via (N + N)* → (LiN + N)* → (LiN + LiN)* → (Li2N + LiN)* → (Li2N + Li2N)* → (Li3N + Li2N)* → (Li3N + Li3N)* to form two isolated Li3N* on M2C MXenes. The calculated charge-discharge overpotentials decrease in the order of Sc2C < Ti2C < V2C. Notably, the Sc2C MXene has great potential as a cathode catalyst for Li-N2 batteries because of its high electrical conductivity, strong N2 adsorption, favorable Li-mediated N2 dissociation, and ultralow discharging, charging, and total overpotentials (0.07, 0.06, and 0.13 V). This study offers a theoretical foundation for future research on Li-N2 batteries.

Sperm retrieval outcomes of contralateral testis in men with nonobstructive azoospermia and unsuccessful unilateral microdissection testicular sperm extraction.

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