Improving Interfacial Adhesion of Graphite/Epoxy Composites by Surface Functionalization.

Graphite/epoxy resin (G/EP) composites are extensively utilized in bipolar plates for fuel cells owing to their outstanding electrical and mechanical properties. However, the mechanical strength of these composites declines notably due to the inadequate bonding interface between graphite and epoxy resin. To address this issue, we used molecular dynamics (MD) simulations to study the influence of graphite surface functionalization on the interfacial structures of composites. The results of this study revealed that the functionalization of the graphite surface led to an increase in the interface thickness of the composite. This phenomenon can be attributed to the interdiffusion and hydrogen bond formation between functionalized graphite and epoxy molecular chains. And all four types of functional groups demonstrated a promoting effect on the adsorption process. Additionally, the adsorption and contact angle results provided further evidence that the adsorption rate of graphite to the epoxy resin significantly improved after functionalization. These findings contribute to a more comprehensive understanding of the microscopic process of forming interfaces in G/EP composites. In addition, these insights provide valuable guidance for improving the interface bonding of composite bipolar plates, which can ultimately increase their mechanical strength.

Fast Fabrication of WS2/Bi2Se3 Heterostructures for High-Performance Photodetection.

Two-dimensional (2D) material heterostructures have attracted considerable attention owing to their interesting and novel physical properties, which expand the possibilities for future optoelectronic, photovoltaic, and nanoelectronic applications. A portable, fast, and deterministic transfer technique is highly needed for the fabrication of heterostructures. Herein, we report a fast half-wet poly(dimethylsiloxane) (PDMS) transfer process utilizing the change of adhesion energy with the help of micron-sized water droplets. Using this method, a vertical stacking of the WS2/Bi2Se3 heterostructure with a straddling band configuration is successfully assembled on a fluorophlogopite substrate. Thanks to the complementary band gaps and high efficiency of interfacial charge transfer, the photodetector based on the heterostructure exhibits a superior responsivity of 109.9 A W-1 for a visible incident light at 473 nm and 26.7 A W-1 for a 1064 nm near-infrared illumination. Such high photoresponsivity of the heterostructure demonstrates that our transfer method not only owns time efficiency but also ensures high quality of the heterointerface. Our study may open new pathways to the fast and massive fabrication of various vertical 2D heterostructures for applications in twistronics/valleytronics and other band engineering devices.

Atomically Smooth Single-Crystalline Platform for Low-Loss Plasmonic Nanocavities.

Nanoparticle-on-mirror plasmonic nanocavities, capable of extreme optical confinement and enhancement, have triggered state-of-the-art progress in nanophotonics and development of applications in enhanced spectroscopies. However, the optical quality factor and thus performance of these nanoconstructs are undermined by the granular polycrystalline metal films (especially when they are optically thin) used as a mirror. Here, we report an atomically smooth single-crystalline platform for low-loss nanocavities using chemically synthesized gold microflakes as a mirror. Nanocavities constructed using gold nanorods on such microflakes exhibit a rich structure of plasmonic modes, which are highly sensitive to the thickness of optically thin (down to ∼15 nm) microflakes. The microflakes endow nanocavities with significantly improved quality factor (∼2 times) and scattering intensity (∼3 times) compared with their counterparts based on deposited films. The developed low-loss nanocavities further allow for the integration with a mature platform of fiber optics, opening opportunities for realizing nanocavity-based miniaturized photonic devices for practical applications.

Pre-Lithiation Strategies for Next-Generation Practical Lithium-Ion Batteries.

Next-generation Li-ion batteries (LIBs) with higher energy density adopt some novel anode materials, which generally have the potential to exhibit higher capacity, superior rate performance as well as better cycling durability than conventional graphite anode, while on the other hand always suffer from larger active lithium loss (ALL) in the first several cycles. During the last two decades, various pre-lithiation strategies are developed to mitigate the initial ALL by presetting the extra Li sources to effectively improve the first Coulombic efficiency and thus achieve higher energy density as well as better cyclability. In this progress report, the origin of the huge initial ALL of the anode and its effect on the performance of full cells are first illustrated in theory. Then, various pre-lithiation strategies to resolve these issues are summarized, classified, and compared in detail. Moreover, the research progress of pre-lithiation strategies for the representative electrochemical systems are carefully reviewed. Finally, the current challenges and future perspectives are particularly analyzed and outlooked. This progress report aims to bring up new insights to reassess the significance of pre-lithiation strategies and offer a guideline for the research directions tailored for different applications based on the proposed pre-lithiation strategies summaries and comparisons.

Electrode Materials, Electrolytes, and Challenges in Nonaqueous Lithium-Ion Capacitors.

Among the various energy-storage systems, lithium-ion capacitors (LICs) are receiving intensive attention due to their high energy density, high power density, long lifetime, and good stability. As a hybrid of lithium-ion batteries and supercapacitors, LICs are composed of a battery-type electrode and a capacitor-type electrode and can potentially combine the advantages of the high energy density of batteries and the large power density of capacitors. Here, the working principle of LICs is discussed, and the recent advances in LIC electrode materials, particularly activated carbon and lithium titanate, as well as in electrolyte development are reviewed. The charge-storage mechanisms for intercalative pseudocapacitive behavior, battery behavior, and conventional pseudocapacitive behavior are classified and compared. Finally, the prospects and challenges associated with LICs are discussed. The overall aim is to provide deep insights into the LIC field for continuing research and development of second-generation energy-storage technologies.

A hybrid electrochemical device based on a synergetic inner combination of Li ion battery and Li ion capacitor for energy storage.

Li ion battery (LIB) and electrochemical capacitor (EC) are considered as the most widely used energy storage systems (ESSs) because they can produce a high energy density or a high power density, but it is a huge challenge to achieve both the demands of a high energy density as well as a high power density on their own. A new hybrid Li ion capacitor (HyLIC), which combines the advantages of LIB and Li ion capacitor (LIC), is proposed. This device can successfully realize a potential match between LIB and LIC and can avoid the excessive depletion of electrolyte during the charge process. The galvanostatic charge-discharge cycling tests reveal that at low current, the HyLIC exhibits a high energy density, while at high current, it demonstrates a high power density. Ragone plot confirms that this device can make a synergetic balance between energy and power and achieve a highest energy density in the power density range of 80 to 300 W kg-1. The cycle life test proves that HyLIC exhibits a good cycle life and an excellent coulombic efficiency. The present study shows that HyLIC, which is capable of achieving a high energy density, a long cycle life and an excellent power density, has the potential to achieve the winning combination of a high energy and power density.

Vector representation and its application of DNA sequences based on nucleotide triplet codons.

Compared with single nucleotide, nucleotide triplet appears to contain more biological and genetic information, so it has been applied widely. We propose a new 3D-vector representation method of DNA sequences, namely use molecular weight of nucleotide triplet to define the '0' molecular plane, then make the 3-D coordinate transformation to map a DNA sequence into a curve by the coordinate accumulation, and then extract the D/D matrix's eigenvalues to describe, compare and analyze the DNA sequences as the numerical characterization. It is a new idea for comparison and phylogenetic trees' reconstruction of biological sequences.

Facile Fabrication of N-Doped Graphene as Efficient Electrocatalyst for Oxygen Reduction Reaction.

A facile bottom-up method is reported here for the fabrication of N-doped graphene for oxygen reduction. It consists of a two-step calcination strategy and uses α-hydroxy acids (AHAs) as carbon source and melamine as nitrogen source. Three different AHAs, malic acid, tartaric acid, and citric acid, were chosen as the carbon sources. The prepared N-doped graphenes have a typical thin layered structure with a large specific surface area. It was found that the N content in the obtained N-doped graphenes varies from 4.12 to 8.11 at. % depending on the AHAs used. All of the samples showed high performance in oxygen reduction reaction (ORR). The N-doped graphene prepared from citric acid demonstrated the highest electrocatalytic activity, which is comparable to the commercial Pt/C and exhibited good durability, attributing to the high pyridinic N content in the composite.

Low initial human papillomavirus viral load may indicate worse prognosis in patients with cervical carcinoma treated with surgery.

OBJECTIVE: To evaluate the prognostic implication of human papillomavirus (HPV) viral load in cervical cancer patients who underwent radical hysterectomy. METHODS: We conducted a retrospective review of patients with stage IA2 through stage IIIA cervical carcinoma who underwent radical hysterectomy at Sun Yat-sen University Cancer Center between January 2005 and December 2009. Patients who had undergone preoperative hybrid capture 2 testing to detect HPV DNA were included. A total of 346 patients positive for HPV DNA were enrolled and stratified into two groups according to the median HPV viral load. RESULTS: HPV viral load was significantly correlated with lymphovascular space invasion (p=0.026) and deep stromal invasion (p=0.024). However, other factors, such as age, stage, histologic grade, histologic type, lymph node metastasis, and tumor size, were not significantly associated with viral load. Low HPV viral load was correlated with poor disease-free survival in univariate analysis (p=0.037) and multivariate analysis (p=0.027). There was no significant difference in overall survival with regard to initial HPV viral load. CONCLUSION: Low initial HPV viral load may be a poor prognostic factor for cervical cancer patients who have undergone radical hysterectomy.

Selenadiazole derivatives as potent thioredoxin reductase inhibitors that enhance the radiosensitivity of cancer cells.

Thioredoxin system is an attractive target to overcome radioresistance in cancer therapy. The redox enzyme thioredoxin reductase (TrxR) plays a vital role in restoring cellular thiol redox balance disrupted by radiation-induced reactive oxygens species (ROS) generation and oxidative damage. In this study, a series of 1,2,5-selenadiazoles have been synthesized and identified as highly effective inhibitors of TrxR to disrupt the intracellular redox balance, and thus significantly enhanced the sensitivity of cancer cells to X-ray. Upon irradiation, 1,2,5-selenadiazoles displayed a marked synergistic inhibitory effect on radioresistant A375 melanoma cell through enhancement of ROS overproduction, and subsequent induction of ROS-promoted apoptotic pathways, which triggered then mitochondrial dysfunction and caspase activation, finally resulted in augment of radiotherapeutic efficacy. Interestingly, we also found the interaction sites between 1,2,5-selenadiazole and the model peptide of TrxR, which can be confirmed by MALDI-ToF-MS. These results clearly demonstrate TrxR as a potential target for therapy of radioresistant cancers, and selenadiazole derivatives may be attractive radiosensitizing agent by targeting TrxR.

Synergistic induction of apoptosis by methylseleninic acid and cisplatin, the role of ROS-ERK/AKT-p53 pathway.

Cisplatin-based therapy is one of the most important chemotherapy treatments for cancers. However, its efficacy is greatly limited by drug resistance and undesirable side effects. Therefore, it is of great importance to develop chemosensitizing agents to cisplatin. In the present study, we demonstrated the strategy to use methylseleninic acid (MeSe) as a synergistic agent of cisplatin and elucidated their action mechanisms. The combination of MeSe and cisplatin exhibited synergistic anticancer efficacy and achieved greater selectivity between cancer cell and normal cell. By inducing intracellular oxidative stress, MeSe potentiated cisplatin-induced DNA damage and led to enhanced p53 phosphorylation, followed by increased activation of both mitochondrial and death receptor pathway. Down-regulation of phosphorylated AKT and ERK also played important roles in the synergistic effects of MeSe and cisplatin. Our results suggested that the strategy to apply MeSe as a synergistic agent to cisplatin could be a highly efficient way to achieve anticancer synergism by targeting the intracellular redox system. MeSe might be a candidate for clinical application as a chemosensitizer to cisplatin-based therapy for cancer treatments, especially for hepatocellular carcinoma.

Sialic acid surface decoration enhances cellular uptake and apoptosis-inducing activity of selenium nanoparticles.

A simple method for fabrication of sialic acid surface-decorated selenium nanoparticles (SA-Se-NPs) with enhanced cancer-targeting and cell-penetrating abilities has been demonstrated in the present study. Monodisperse and homogeneous spherical SA-Se-NPs with striking stability were prepared under the optimized conditions. SA surface decoration significantly increased the cellular uptake and cytotoxicity of Se-NPs in HeLa human cervical carcinoma cells. Treatments of SA-Se-NPs induced dose-dependent apoptosis in HeLa cells, as evidenced by increase in sub-G1 cell populations, nuclear condensation and formation of apoptotic bodies. Further investigation on molecular mechanisms reveals that SA-Se-NPs triggered cancer cell apoptosis through activation of caspase-3 and subsequent cleavage of PARP.

[Artesunate suppresses human endometrial carcinoma RL95-2 cell proliferation by inducing cell apoptosis].

OBJECTIVE: To investigate the inhibitory effect of artesunate on human endometrial carcinoma RL95-2 cell line proliferation in vitro and the possible mechanisms. METHODS: The inhibitory effect of artesunate on the cell proliferation was assessed with MTT assay. Transmission electron miscrosopy was used to observe the morphological change of the cells after the treatment. Flow cytometry was performed to examine the changes in the cell cycle, reactive oxygen species (ROS) levels (with DCFH-DA labeling) and mitochondrial membrane potential (rhodamine123 staining), and caspase-3 activity was detected by immunohistochemistry. RESULTS: Artesunate inhibited the proliferation of RL95-2 cells with an IC(50) of 26.29 microg/ml. Transmission electron microscopy revealed early apoptotic changes of the cells with obvious chromatin fragmentation. The cell cycle arrest at G(0)/G(1) phase was observed by flow cytometry, and immunohistochemistry demonstrated caspase-3 positivity in cytoplasm. ROS generation in the cells increased obviously after treatment with artesunate for 72 h, which also resulted in lowered mitochondrial membrane potential. CONCLUSION: Artesunate suppressed the proliferation of RL95-2 cells in vitro possibly by inducing cell apoptosis.

[Effects of exogenous human chorionic gonadotropin on nude mice bearing endometrial carcinoma].

OBJECTIVE: To observe the effects of exogenous human chorionic gonadotropin (hCG) on nude mice bearing transplanted endometrial carcinoma. METHODS: Human endometrial carcinoma xenograft was transplanted in nude mice, and the effects of hCG injection on the tumor growth was evaluated according to tumorigenesis and xenograft weights. The expression of Ki-67 in the tumor was determined by immunohistochemistry, and HE staining was performed for morphological observation and measurement of the necrosis area in the tumor. The effect of hCG on fibrosis in the tumor was evaluated with Masson staining. RESULTS: Compared to normal saline-treated tumor-bearing mice, the mice with hCG treatment showed increased tumor weight. HE staining for tumors in HCG-treatment group visualized tumor cell arrangement in glandular structure with smaller necrosis area, and Masson staining identified thick and compact collagen fibers as compared with the thin and loosely arranged fibers in saline-treated group. No significant difference was found in the Ki-67 expression in the tumors between the two groups. CONCLUSION: Exogenous hCG can promote the differentiation of the endometrial carcinoma cells in vivo.

Effects of microstructure of carbon nanofibers for amperometric detection of hydrogen peroxide.

Carbon nanofibers (CNFs) with three microstructures, including platelet-carbon nanofibers (PCNFs), fish-bone-carbon nanofibers (FCNFs), and tube-carbon nanofibers (TCNFs), were synthesized, characterized, and evaluated for electrochemical sensing of hydrogen peroxide. The CNFs studied here show microstructures with various stacked morphologies. The sizes and graphite-layer ordering of the CNFs can be well controlled. Glassy carbon (GC) electrodes modified by CNFs were fabricated and compared for amperometric detection of hydrogen peroxide. Sensors based on PCNFs/GC, FCNFs/GC, and TCNFs/GC were used in the amperometric detection of H2O2 in solution by applying a potential of +0.65 V versus Ag/AgCl at the working electrode. The highest electrocatalytic performance was observed for PCNFs/GC among the three types of hydrogen peroxide sensors. The amperometric response of PCNFs/GC retained over 90% of the initial current of the first day up to 21 days. The linear range is from 1.80x10(-4) to 2.62x10(-3) M with a correlation coefficient larger than 0.999 and with a detection limit of 4.0 microM H2O2 (S/N = 3). The relative standard deviation for detecting 1.80x10(-4) M H2O2 (N = 8) is 2.1% with an average response of 0.64 microA. The significant diversity of electrocatalytic activity of the CNFs toward the oxidation of hydrogen peroxide may result from the difference of morphologies, textural properties, and crystalline structures.

[Association of p16, p53, Ki-67 expressions with high-risk human papilloma virus infection in cervical intraepithelial neoplasia].

OBJECTIVE: To investigate the association between p16, p53 and Ki-67 expression and high-risk human papilloma virus (HPV) infection in cervical intraepithelial neoplasia (CIN). METHODS: Using a self-prepared tissue microarray, p16, p53, and Ki-67 expression was detected in 243 cases of CIN and 30 cases of normal cervical epitheliums by immunohistochemistry, and high-risk HPV infection was detected by gene hybridization capture II. RESULTS: p16, p53 and Ki-67 expressions were all negative in normal cervical epitheliums, but all positive in CIN. The expression of p16 and Ki-67 was 88.2 (67/76) and 92.1% (70/76) in CIN grade 1, respectively, and both were 100% in CIN grades 2 and 3, and the intensity of positive expression was significantly correlated with CIN grade (P<0.001). The positive cells in CIN grade 1 were mostly within the lower 1/3 of the squamous epithelium, while in CIN grade 2, the positive cells involved the lower 2/3 of the epithelium layers; in CIN grade 3, more than 2/3 or almost the full thickness of the epithelium was involved, suggesting significant correlation between the involvement and CIN grades (P<0.001). p53 expression was positive in 31.6% (24/76) of the cases in CIN grade 1, 53.4% (47/88) in CIN grade 2 and 58.2% (46/79) in CIN grade 3, and the intensity of positive expression was in significantly correlation with CIN grades (P<0.001), but no significant difference occurred between CIN 2 and CIN 3. High-risk HPV were detected in 37/52 (71.2%) of the cases in CIN grade 1, 50/58 (86.2%) in CIN 2 and 50/55 (90.9%) in CIN 3, and the relative DNA amount was significantly correlated with CIN grade (P<0.001), but there as no significant difference between CIN 2 and CIN 3. CONCLUSIONS: High-risk HPV infection and p16, p53, Ki-67 overexpression all play important roles in the carcinogenesis of cervical precancerous lesion, and both p16 and Ki-67 expression are useful markers in diagnosis and staging of CIN.