Atomically Engineered Encapsulation of SnS2 Nanoribbons by Single-Walled Carbon Nanotubes for High-Efficiency Lithium Storage.

Rechargeable lithium-ion batteries are integral to contemporary energy storage, yet current anode material systems struggle to meet the increasing demand for extended range capabilities. This work introduces a novel composite anode material composed of one-dimensional 2H-phase tin disulfide (SnS2) nanoribbons enclosed within cavities of single-walled carbon nanotubes (SnS2@SWCNTs), achieved through precise atomic engineering. Employing aberration-corrected transmission electron microscopy, we precisely elucidated the crystal structure of SnS2 within the confines of the SWCNTs. This deliberate design effectively addresses the inherent limitations of SnS2 as a lithium-ion anode material, including its low electrical conductivity, considerable volume expansion effects, and unstable solid electrolyte interface membrane. Testing confirmed that SnS2 transforms into the Li5Sn2 alloy phase after full lithiation and back to SnS2 after delithiation, showing excellent reversibility. The composite also benefits from edge effects, improving lithium storage through stronger binding and lower migration barriers, which were supported by calculations. This pioneering work advances high-performance anode materials for applications.

Insights into electron dynamics in two-dimensional bismuth oxyselenide: a monolayer-bilayer perspective.

Bismuth oxyselenide (Bi2O2Se), an emerging 2D semiconductor material, has garnered substantial attention owing to its remarkable properties, including air stability, elevated carrier mobility, and ultrafast optical response. In this study, we conduct a comparative analysis of electron excitation and relaxation processes in monolayer and bilayer Bi2O2Se. Our findings reveal that monolayer Bi2O2Se exhibits parity-forbidden transitions between the band edges at the Γ point, whereas bilayer Bi2O2Se demonstrates parity activity, providing the bilayer with an advantage in light absorption. Employing nonadiabatic molecular dynamics simulations, we uncover a two-stage hot-electron relaxation process-initially fast followed by slow-in both monolayer and bilayer Bi2O2Se within the conduction band. Despite the presence of weak nonadiabatic coupling between the CBM + 1 and CBM, limiting hot electron relaxation, the monolayer displays a shorter relaxation time due to its higher phonon-coupled frequency and smaller energy difference. Our investigation sheds light on the layer-specific excitation properties of 2D Bi2O2Se layered materials, providing crucial insights for the strategic design of photonic devices utilizing 2D materials.

A theoretical study on the line defects in ß12-borophene: enhanced direct-current and alternating-current conductances.

Using density functional theory and the non-equilibrium Green's function method, we theoretically investigated the structures, stabilities, electronic properties, and the direct-current (DC) and alternating-current (AC) transport properties of the line defects in two-dimensional material ß12-borophene. Our results suggest that there exist six line defects that can enhance the stability of ß12-borophene and the line defects have profound influences on the electronic structure of ß12-borophene. Along the zigzag direction, the line defects can change the atomic orbital components of the Dirac cones in perfect ß12-borophene, but the line defects along the armchair direction have complicated influences on the Dirac cones. In the case of DC transport, some of the line defects lead to the constant DC phenomenon and the negative differential resistance effect, and enhance the DC conductances since the line defects exhibit typical one-dimensional characteristics. In the case of AC transport, some of the line defects enhance the AC conductances in the medium-frequency and high-frequency ranges through the photon-assisted tunneling effect. The microscopic mechanisms of the enhanced DC and AC conductances are different. In addition, for a low-frequency range, the equivalent circuits of ß12-borophene and the line defects were also suggested, which will be beneficial for designing borophene-based functional nanodevices.

BMP4 Regulates EMT to be Involved in non-Syndromic Cleft lip With or Without Palate.

OBJECTIVE: In the previous study, we identified bone morphogenetic protein 4 (BMP4) responsible for non-syndromic cleft lip with or without cleft palate (NSCL/P). We aimed to elucidate the effects and mechanisms of BMP4 on epithelial-mesenchymal transition (EMT) through Smad1 signaling pathway to be involved in NSCL/P. METHODS: The human oral epidermoid carcinoma cells (KBs) were transfected with plasmids or small interfering RNA (siRNA) to build the models. The migration of the cells was evaluated by transwell assay. Western blotting and quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) were used to detect the expressions of BMP4, E-cadherin, N-cadherin, EMT-related transcription factors snal1 and snal2, matrix metalloproteinase 2 (MMP2), MMP9, Smad1, and phosphorylated Smad1. RESULTS: In the overexpression group, the migration number of cells was increased significantly. The protein expression of E-cadherin was decreased significantly, while the protein expression level of the N-cadherin was increased significantly. The protein and mRNA expressions of MMP2, MMP9, snal1, and snal2 were significantly higher. The expression level of Smad1 was not significantly changed, while the phosphorylation of Smad1 was significantly increased. In the BMP4-siRNA group, the migrating number cells was significantly decreased. The protein expression of E-cadherin was increased significantly, while the expression of N-cadherin was significantly decreased. The protein and mRNA expressions of MMP2, MMP9, snal1, and snal2 were significantly lower than that of the control group. The expressions of Smad1 and phosphorylation of Smad1 were not significantly changed. CONCLUSIONS: BMP4 enhances cell migration and promotes cell EMT through Smad1 signaling pathway. Abnormal BMP4 mediates migration and EMT through other relevant signaling pathways resulting in NSCL/P. The study provides new insight into the mechanisms of NSCL/P associated with BMP4.n.

Determining the origin of poor electronic conductivity and ultrafast ionic conductivity in Na3V2(PO4)2FO2 based on first principles and ab initio molecular dynamics methods.

Sodium ion technology is increasingly investigated as a low-cost solution for grid storage applications. Among the reported cathode materials for sodium-ion batteries, Na3V2(PO4)2FO2 is considered as one of the most promising materials due to its high operation voltage and good cyclability. Here, the de-sodiumization process of Na3V2(PO4)2FO2 has been systematically examined using first-principles calculations to uncover the fundamental questions at the atomic level. Four stable intermediate products during the de-sodiumization process are firstly determined based on the convex hull, and three voltage platforms are then predicted. Except for two voltage platforms (3.37 V and 3.75 V) close to the experimental values, the platform up to 5.28 V exceeds the stability window (4.8 V) of a typical electrolyte, which was not observed experimentally. Excitingly, the change of volume is only 2% during the sodiumization process, which should be the reason for the good cycling stability of this material. Electronic structure analysis also reveals that the valence states of V ions will be changed from V5+ to V4+ during the sodiumization process, resulting in a weak Jahn-Teller distortion in VO5F octahedra, and then making the lattice-constants asymmetrically change. More seriously, combined with a bandgap of 2.0 eV, the conduction band minimum mainly composed of V-t2g non-bonding orbitals has strong localized characteristics, which should be the intrinsic origin of poor electron transport properties for NaxV2(PO4)2FO2. Nonetheless, benefiting from the layer-like structure features with F-segmentation, this material has an ultrafast sodium ionic conductivity comparable to that of NASICON, with an activation energy of only 82 meV. Therefore, our results indicate that maintaining layer-like features and regulating V atoms will be important directions to improve the performance of NaxV2(PO4)2FO2.

Modelling high performance potassium-ion battery anode materials with two-dimensional vanadium carbide MXene: the role of surface O- and S-terminations.

Due to the low cost, high element abundance and intrinsic safety, potassium-ion batteries (KIBs) have attracted a surge of interest in recent years. Currently, the key challenge and obstacle to the development of KIBs is to find suitable anode materials with large capacity, high rate capability and small lattice changes during the charge/discharge process. MXenes with excellent energy storage properties are promising anode materials for KIBs and their energy performance largely depends on the surface termination. Here, two-dimensional O- and S-terminated V2C MXene anode materials are designed to model high performance potassium-ion batteries. Using first-principles calculations, the structural properties and potential battery performance in KIBs of V2CO2 and V2CS2 are systematically investigated. The inherent metallic nature, a small diffusion barrier, a low average open circuit voltage, and a high theoretical specific capacity (489.93 mA h g-1 of V2CO2 and 200.24 mA h g-1 of V2CS2) demonstrate that both of them are ideal anode materials for KIBs. Meanwhile, we also investigated the mechanism of the difference in energy performance between V2CO2 and V2CS2 at atomic and electronic levels, in other words, the energy performance difference introduced by surface O- and S-terminations.

A boron-exposed TiB3 monolayer with a lower electrostatic-potential surface as a higher-performance anode material for Li-ion and Na-ion batteries.

The lack of high-performance anode materials has become a major obstacle to the development of Li- and Na-ion batteries. Recently, 2D transition metal borides (e.g. MBenes) have attracted much attention due to their excellent stability and electrical conductivity. Unfortunately, most of the reported MBene phases typically have an intrinsic metal-rich structure with metal atoms exposed on the surface, which harmfully affect the adsorption of Li/Na atoms. Here, through crystal structure prediction combined with the first-principles density functional theory, a novel TiB3 MBene has been determined by altering the proportion of non-metallic element boron to wrap metal atoms and weaken nearest-neighbor electrostatic repulsion. Electrostatic potential analysis visually shows a surface with low potential on the TiB3 monolayer implying high adsorption capacity, and also can be used to quickly screen out the Li/Na adsorption sites. Accurate half-cell battery simulation confirmably shows that the TiB3 monolayer possesses a theoretical specific capacity of 1335.04 and 667.52 mA h g-1 for Li and Na, respectively. The TiB3 monolayer can remain metallic after adsorbing Li/Na atoms, which ensures good conductivity during battery cycling. The ultra-low barrier energy (only 38 meV for Li) and suitable open-circuit voltage indicate excellent charging and discharging capabilities. These results suggest that the TiB3 monolayer could be a promising anode material for Li- and Na-ion batteries, and provide a simple design principle for exposing non-metallic atoms on the surface.

Sulfur-functionalized vanadium carbide MXene (V2CS2) as a promising anchoring material for lithium-sulfur batteries.

The development of lithium-sulfur (Li-S) batteries is hindered by capacity loss due to lithium polysulfide (LIPS) dissolution into electrolyte solutions (known as the "shuttle effect"). MXenes with excellent electrical conductivity, high mechanical strength and multiple possible active two-dimensional surface terminations are attracting much attention as anchoring materials of Li-S batteries. Here, the S-functionalized V2C (V2CS2) is designed and demonstrated to have not only dynamic and thermal stability, but also metallic character. Compared with bare V2C and V2CO2, V2CS2 exhibits a moderate adsorption effect to suppress the "shuttle effect" and can preserve the structure of LIPSs without any decomposition. Moreover, the metallic properties of V2CS2 are maintained after LIPSs are adsorbed, which can promote the electrochemical activity during the charge and discharge process. The low energy barriers of Li2S decomposition and Li diffusion on the V2CS2 surface promise the phase transformation of LIPSs and assist the electrochemical process. Based on these remarkable results, we can conclude that V2CS2 is a promising anchoring material for lithium-sulfur batteries. Our work may also inspire the exploration of other MXenes and new surface functionalization methods to improve the performance of MXenes as host materials for high performance Li-S batteries.

Spin-filtering and tunneling magnetoresistance effects in 6,6,12-graphyne-based molecular magnetic tunnel junctions.

In the present study, by cutting 6,6,12-graphyne along vertical and horizontal directions, two kinds of 6,6,12-graphyne nanodots (6,6,12-GYNDs) with different sizes are obtained. Using these 6,6,12-GYNDs, we theoretically designed two kinds of 6,6,12-graphyne-based molecular magnetic tunnel junctions (MMTJs) and investigated their spin-dependent transport properties. Depending on the orientation of the 6,6,12-GYNDs and the connection of the 6,6,12-GYNDs to electrodes, our results show that the two MMTJs have novel transport behaviors. Two different net spin currents can be obtained by tuning the spin configurations and the maximal order of magnitudes of tunneling magnetoresistance values of the two MMTJs reaches 106%. The high spin-filtering ratio and large tunneling magnetoresistance value provide high sensitivity for practical applications. Therefore, the spin-filtering and tunneling magnetoresistance effects enable 6,6,12-graphyne-based MMTJs to be used as spintronic devices.

The anti-androgenic effects of cypermethrin mediated by non-classical testosterone pathway activation of mitogen-activated protein kinase cascade in mouse Sertoli cells.

Previous studies have demonstrated that the anti-androgenic effects of cypermethrin (CYP) are associated with testosterone (T) - related signaling pathway. This study was to investigate the effects of CYP on mouse Sertoli cells (TM4) and clarify whether the mechanisms were mediated by non-classical T signaling pathway activating mitogen-activated protein kinase (MAPK) cascade. The Cell Counting Kit 8 (CCK8) and Real-Time Cell Analysis iCELLigence (RTCA-iCELLigence) system were performed to detect the effects of 10 µM, 20 µM, 40 µM and 80 µM CYP on the viability and proliferation of TM4. The mammalian two hybrid assay, quantitative Real-Time PCR (qRT-PCR) and western blot were conducted to analyze the key genes and proteins involved in T-mediated MAPK signaling pathway. CYP was found to inhibit the viability and proliferation of TM4. Additionally, CYP disturbed the functions of Sertoli cells by inhibiting inhibin B (INH B) expression and facilitating androgen binding protein (ABP) and transferrin (TF) expression. Moreover, CYP suppressed the interaction of AR and Src kinase and inhibited androgen-mediated phosphorylation of Src, epidermal growth factor receptor (EGFR), extracellular-regulated kinase1/2 (ERK1/2) and transcription factor cAMP response element binding protein (CREB). Furthermore, the androgen-induced mRNA and protein expression of CREB-regulated gene early growth response factor (Egr1) decreased after treated with CYP. It is indicated that CYP inhibits the viability and proliferation of Sertoli cells and non-classical T signaling pathway activation of MAPK cascade is involved in anti-androgenic effect of CYP. This study provides a novel insight into the CYP-induced reproductive toxicity.

Association of androgen receptor gene CAG and GGN repeat polymorphism with cryptorchidism: A meta-analysis.

Researches on association between variations in the androgen receptor (AR) gene repeat polymorphisms and cryptorchidism (CO) had conflicting results. The aim of this meta-analysis was to analyse the potential effects of AR CAG and/or GGN repeat polymorphism on CO. Studies were independently appraised by two investigators on PubMed, Web of Science, EBSCO databases and Foreign Medical Retrieval System. Case-control studies with measurement of CAG and/or GGN repeat length were included. Weighted mean difference (WMD) and 95% confidence intervals (CIs) for the CAG or GGN repeat polymorphism and CO were calculated. Five reports were included in this analysis. Overall, no difference was identified between patients and fertile men in CAG repeat length. However, when the CO was divided into unilateral and bilateral, longer CAG repeat region was significantly associated with CO in bilateral group (WMD = 0.74; 95% CI, 0.01-1.47; p < .05). In addition, GGN lengths were significantly higher in patients compared with those in controls (WMD = 1.17; 95% CI, 0.28-2.06; p < .05). No obvious effect was found in the GGN length when compared unilateral or bilateral group with control respectively. The results in this meta-analysis indicated that AR CAG and GGN repeat polymorphisms may be an important pathogenesis of CO.

Evaluation of the New Automatic Mycob.T Stainer and Scanner for Detecting Acid-fast Bacilli in China.

OBJECTIVE: To validate the performance of Mycob. T Stainer and Scanner (MTSS) for detecting acid-fast bacilli (AFB). METHODS: A total of 3,816 sputum samples from 1,515 tuberculosis (TB) suspects were tested at the Anhui Provincial Chest Hospital and the Linyi People's Hospital from April-August, 2016. Each specimen was placed on two smear slides. One slide was stained by the ziehl-neelsen (ZN) method to be read by conventional microscopy (CM). The other slide was stained and scanned by MTSS. All specimens were decontaminated with 4% NaOH, and then inoculated into solid culture. The performance of MTSS was assessed. RESULTS: MTSS produced higher average positivity rate (27.96%) as compared with the CM (26.83%). The overall sensitivity and specificity of MTSS were 78.9% and 93.9%, respectively. The sensitivity and specificity of CM was 77.4% and 95.0%, respectively. CONCLUSION: MTSS exhibited a favorable performance in the detection of AFB. It may be an alternative to CM for screening TB.

Overexpression of YOD1 Promotes the Migration of Human Oral Keratinocytes by Enhancing TGF-ß3 Signaling.

OBJECTIVE: To investigate the effects of YOD1 overexpression on the proliferation and migration of human oral keratinocytes (HOKs), and to clarify whether the mechanisms involve transforming growth factor-ß (TGF-ß) signaling. METHODS: HOKs were transfected with the plasmid pEGFP-N3-YOD1 containing YOD1. The mRNA levels of YOD1 and TGF-ß were determined by qPCR. The protein expressions of YOD1, TGF-ß, Smad2/3, Smad4, and phospho-Smad2/3 were determined by western blotting. Cell proliferation and migration were evaluated by Cell Counting Kit-8 assay and wound healing assay, respectively. RESULTS: The mRNA and protein levels of YOD1 were higher in HOKs transfected with YOD1. YOD1 overexpression significantly enhanced the migration of HOKs. The mRNA and protein levels of TGF-ß3 were increased by YOD1 overexpression. HOKs transfected with YOD1 exhibited increased phospho-Smad2/3 levels. CONCLUSION: YOD1 overexpression enhances cell migration by promoting TGF-ß3 signaling which may play an important role in lip and palate formation. YOD1 mutation may contribute to aberrant TGF-ß3 signaling associated with decreased cell migration resulting in NSCLP.

Association Between CRISPLD2 Polymorphisms and the Risk of Nonsyndromic Clefts of the Lip and/or Palate: A Meta-analysis.

OBJECTIVE: Nonsyndromic clefts of the lip and/or palate (NSCL/P) are one of the most common polygenic diseases. Recently, many studies focused on the association between CRISPLD2 polymorphisms and NSCL/P risk. However, some studies have shown opposite results. In this study, meta-analysis was used to confirm whether CRISPLD2 polymorphism was associated with NSCL/P, and the possible mechanism between CRISPLD2 and NSCL/P was explored. METHODS: Relevant studies were conducted on PubMed, Ovid, EBSCO, CINAHL, FMRS, Web of Science, CNKI, and Wanfang databases from their inception up to June 31, 2016. Review Manager 5.0.24 was used to analyze whether CRISPLD2 polymorphism was involved in NSCL/P by pooling odds ratios (ORs) and 95% confidence intervals (CIs). Potential publication bias was evaluated by visual inspection of the funnel plot. RESULTS: CRISPLD2 rs4783099 was associated with cleft lip and/or palate (CL/P) statistically (OR = 3.18, P < .01). Compared to genotype TT, genotypes CC and CT were correlated significantly (OR = 2.04, P = .04) with CL/P. No evidence showed an association between genetic variation at the CRISPLD2 locus and cleft palate only (CP). CONCLUSION: The polymorphism of CRISPLD2 rs4783099 is correlated with an increased risk of CL/P.

Cypermethrin inhibits interleukin-6-induced androgen receptor transactivation through signal transducer and activator of transcription 3.

The insecticide cypermethrin has been considered as an endocrine-disrupting chemicals (EDCs) with anti-androgenic activity by interfering with interleukin-6 (IL-6) - induced ligand-independent AR signaling. The purpose of this study was to clarify whether the signal transducer and activator of transcription 3 (STAT3) was involved in the antagonism effect of cypermethrin. In this study, the Western blot was to test the level of STAT3 phosphorylation and the mammalian two-hybrid assay was developed to assess the AR-STAT3 interaction. The date showed that IL-6 increased the phosphorylation level of STAT3 and enhanced the AR-STAT3 interaction. Cypermethrin did not affect the phosphorylation level of STAT3 induced by IL-6, while suppressed the AR-STAT3 interaction induced by IL-6 significantly at the concentration of 10-5 M (p < 0.05). The study indicates cypermethrin inhibits IL-6-induced AR signaling by suppressing the interaction between the AR and STAT3. We provide a novel mechanism of cypermethrin-mediated antagonism on IL-6-induced AR activation associated with STAT3.

Hydrogenated borophene as a stable two-dimensional Dirac material with an ultrahigh Fermi velocity.

The recent synthesis of monolayer borophene (triangular boron monolayer) on a substrate has opened the era of boron nanosheets (Science, 2015, 350, 1513), but the structural instability and a need to explore the novel physical properties are still open issues. Here we demonstrated that borophene can be stabilized by full surface hydrogenation (borophane), from first-principles calculations. Most interestingly, our calculations show that borophane has direction-dependent Dirac cones, which are mainly caused by the in-plane px and py orbitals of boron atoms. The Dirac fermions possess an ultrahigh Fermi velocity of up to 3.5 × 106 m s-1 under the HSE06 level, which is 4 times higher than that of graphene. The Young's moduli are calculated to be 190 and 120 GPa nm along two different directions, which are comparable to those of steel. The ultrahigh Fermi velocity and good mechanical features render borophane ideal for nanoelectronic applications.

A Case-control Study of Environmental Risk Factors for Nonsyndromic Cleft of the Lip and/or Palate in Xuzhou, China.

In this study, we sought to determine the association between environmental factors and nonsyndromic cleft of the lip and/or palate (NSCLP) to understand the etiology of the disease. A total of 200 NSCLP cases and 327 controls were recruited at the Maternal and Child Health Hospital of Xuzhou City. We conducted face-to-face interviews with the mothers of both cases and controls. The factors increasing the risk of NSCLP were a positive family history [odds ratio (OR)=56.74], pesticide exposure (OR=8.90), and indoor decoration pollution (OR=4.32). On the other hand, the factors decreasing the risk of NSCLP were a high education level (OR=0.22) and supplementation of folic acid (OR=0.23) and multivitamins (OR=0.16). Positive family history, pesticide exposure, and indoor decoration pollution are associated with the risk of NSCLP. In contrast, high education level and folic acid and multivitamin supplementation are protective factors against NSCLP.

Identification of susceptibility genes in non-syndromic cleft lip with or without cleft palate using whole-exome sequencing.

BACKGROUND: Non-syndromic cleft lip with or without cleft palate (NSCL/P) is among the most common congenital malformations. The etiology of NSCL/P remains poorly characterized owing to its complex genetic heterogeneity. The objective of this study was to identify genetic variants that increase susceptibility to NSCL/P. MATERIAL AND METHODS: Whole-exome sequencing (WES) was performed in 8 fetuses with NSCL/P in China. Bioinformatics analysis was performed using commercially available software. Variants detected by WES were validated by Sanger sequencing. RESULTS: By filtering out synonymous variants in exons, we identified average 8575 nonsynonymous single nucleotide variants (SNVs). We subsequently compared the SNVs against public databases including NCBI dbSNP build 135 and 1000 Genomes Project and obtained an average of 203 SNVs. Total 12 reported candidate genes were verified by Sanger sequencing. Sanger sequencing also confirmed 16 novel SNVs shared by two or more samples. CONCLUSIONS: We have found and confirmed 16 susceptibility genes responsible for NSCL/P, which may play important role in the etiology of NSCL/P. The susceptibility genes identified in this study will not only be useful in revealing the etiology of NSCL/P but also in diagnosis and treatment of the patients with NSCL/P.

Cypermethrin induces Sertoli cell apoptosis through endoplasmic reticulum-mitochondrial coupling involving IP3R1-GRP75-VDAC1.

A widely used type II pyrethroid pesticide cypermethrin (CYP) is one of endocrine disrupting chemicals (EDCs) with anti-androgenic activity to induce male reproductive toxicology. However, the mechanisms have not been fully elucidated. This study was to explore the effects of CYP on apoptosis of mouse Sertoli cells (TM4) and the roles of endoplasmic reticulum (ER)-mitochondria coupling involving 1,4,5-trisphosphate receptor type1-glucose-regulated protein 75-voltage-dependent anion channel 1 (IP3R1-GRP75-VDAC1). TM4 were cultured with different concentrations of CYP. Flow cytometry, calcium (Ca2+) fluorescent probe, transmission electron microscopy and confocal microscopy, and western blot were to examine apoptosis of TM4, mitochondrial Ca2+, ER-mitochondria coupling, and expressions of related proteins. CYP was found to increase apoptotic rates of TM4 significantly. CYP was shown to significantly increase expressions of cleaved caspase-3, cleaved poly ADP-ribose polymerase (PARP). Concentration of mitochondrial Ca2+ was increased by CYP treatment significantly. CYP significantly enhanced ER-mitochondria coupling. CYP was shown to increase expressions of IP3R, Grp75 and VDAC1 significantly. We suggest that CYP induces apoptosis in TM4 cells by facilitating mitochondrial Ca2+ overload regulated by ER-mitochondria coupling involving IP3R1-GRP75-VDAC1. This study identifies a novel mechanism of CYP-induced apoptosis in Sertoli cells.

Toxic effects of cypermethrin on the male reproductive system: with emphasis on the androgen receptor.

The 15-day intact adult male assay was used to investigate the reproductive toxicity of cypermethrin. We also evaluated the contributions of the androgen receptor (AR) to cypermethrin-induced reproductive impairments. Sixty adult male Sprague-Dawley rats were randomly divided into five groups and treated with different doses of cypermethrin (0, 6.25, 12.5, 25 and 50 mg kg(-1) per day) by oral gavage for 15 days. After the rats were sacrificed, the testes, epididymides, seminal vesicles and prostates were excised and weighed. One testis was frozen to be used for daily sperm production. Another testis was processed for AR immunohistochemical analysis and electron microscopic observation. We found that the weights of prostates were significantly decreased in cypermethrin treatment at doses of 25 and 50 mg kg(-1) per day. Rats treated with cypermethrin at 50 mg kg(-1) per day exhibited a significant reduction in testicular daily sperm production. Seminiferous tubule changes were noted, including atrophy and distorted seminiferous tubules, reduction and deformation of spermatogonia, spermatocyte and disordered arrangement of spermatoblasts. Ultrastructural changes were found in cypermethrin-treated groups with disrupted cellular junctions, abnormal morphology of the nucleus, necrosis of spermatogonia spermatocytes and Sertoli cells. To clarify the possible mechanism, AR expression and the serum levels of testosterone were assayed. AR levels were significantly reduced in the rats treated with cypermethrin and the serum levels of testosterone were reduced in cypermethrin treatment at a dose of 50 mg kg(-1) per day. These data suggested that cypermethrin can induce impairments of the structure of seminiferous tubules and spermatogenesis in the male rats. The impairments can be attributed to the reduced AR expression.