Application of Nano-Crystalline Diamond in Tribology

Nano-crystalline diamond has been extensively researched and applied in the fields of tribology, optics, quantum information and biomedicine. In virtue of its hardness, the highest in natural materials, diamond outperforms the other materials in terms of wear resistance. Compared to traditional single-crystalline and poly-crystalline diamonds, nano-crystalline diamond consists of disordered grains and thus possesses good toughness and self-sharpening. These merits render nano-crystalline diamonds to have great potential in tribology. Moreover, the re-nucleation of nanocrystalline diamond during preparation is beneficial to decreasing surface roughness due to its ultrafine grain size. Nano-crystalline diamond coatings can have a friction coefficient as low as single-crystal diamonds. This article briefly introduces the approaches to preparing nano-crystalline diamond materials and summarizes their applications in the field of tribology. Firstly, nano-crystalline diamond powders can be used as additives in both oil- and water-based lubricants to significantly enhance their anti-wear property. Nano-crystalline diamond coatings can also act as self-lubricating films when they are deposited on different substrates, exhibiting excellent performance in friction reduction and wear resistance. In addition, the research works related to the tribological applications of nano-crystalline diamond composites have also been reviewed in this paper

Biosorption potential of natural, pyrolysed and acid-assisted pyrolysed sugarcane bagasse for the removal of lead from contaminated water

Lead (Pb) is a ubiquitous pollutant which poses serious threats to plants, animals and humans once entered into the food chain via contaminated industrial effluents on their discharge into the surface of water bodies and/or geological materials. This study aimed to examine and compare the biosorption potential of natural sugarcane bagasse (NB), pyrolysed sugarcane bagasse (PB) and acid assisted pyrolysed sugarcane bagasse (APB) for the removal of Pb from contaminated water. To explore this objective, a series of batch experiments were conducted at various adsorbent mass (0.25, 0.5, 0.75, 1.0 g per 100 ml contaminated water), initial Pb concentration (7, 15, 30, 60 and 120 ppm), and contact time (7, 15, 30, 60 and 120 min). Results revealed that all the tested bio-sorbents have potential to adsorb and remove Pb ions from the contaminated water. In this regard, APB proved more effective since it removed 98% of Pb from aqueous solution at initial Pb concentration of 7 ppm and mass of 0.25 g per 100 ml of aqueous solution. The respective values in case of NB and PB were 90 and 95%. For a given adsorbent type, Pb adsorption decreased by increasing the mass from 0.25 to 1.0 g per 100 ml of aqueous solution. However, the greatest Pb removal occurred at adsorbent mass of 1.0 g per 100 ml of aqueous solution. Initial Pb concentration had a great impact on Pb adsorption and removal by adsorbent. The former increased and the latter decreased with the increase in initial Pb concentration from seven to 120 ppm. At seven ppm Pb concentration, maximum Pb removal took place irrespective to the adsorbent type. Out of the total Pb adsorption and removal, maximum contribution occurred within 15 min of contact time between the adsorbate and adsorbent, which slightly increased till 30 min, thereafter, it reached to equilibrium. Application of equilibrium isotherm models revealed that our results were better fitted with Freundlich adsorption isotherm model. Overall, and for the reasons detailed above, it is concluded that sugarcane bagasse has capabilities to adsorb and remove Pb ions from contaminated water. Its bio-sorption potential was considerably increased after pyrolysis and acid treatment

An intelligent neural stem cell delivery system for neurodegenerative diseases treatment

Transplanted stem cells constitute a new therapeutic strategy for the treatment of neurological disorders. Emerging evidence indicates that a negative microenvironment, particularly one characterized by the acute inflammation/immune response caused by physical injuries or transplanted stem cells, severely impacts the survival of transplanted stem cells. In this study, to avoid the influence of the increased inflammation following physical injuries, an intelligent, double‐layer, alginate hydrogel system is designed. This system fosters the matrix metalloproeinases (MMP) secreted by transplanted stem cell reactions with MMP peptide grafted on the inner layer and destroys the structure of the inner hydrogel layer during the inflammatory storm. Meanwhile, the optimum concentration of the arginine‐glycine‐aspartate (RGD) peptide is also immobilized to the inner hydrogels to obtain more stem cells before arriving to the outer hydrogel layer. It is found that blocking Cripto‐1, which promotes embryonic stem cell differentiation to dopamine neurons, also accelerates this process in neural stem cells. More interesting is the fact that neural stem cell differentiation can be conducted in astrocyte‐differentiation medium without other treatments. In addition, the system can be adjusted according to the different parameters of transplanted stem cells and can expand on the clinical application of stem cells in the treatment of this neurological disorder

Potential Ameliorative Effects of Qing Ye Dan Against Cadmium Induced Prostatic Deficits via Regulating Nrf-2/HO-1 and TGF-β1/Smad Pathways

Background/Aims: Cadmium (Cd) is an environmental pollutant with reproductive toxicity. Swertia mileensis is used in Chinese medicine for the treatment of prostatic deficits and named as Qing Ye Dan (QYD). This study was undertaken to investigate the potential protective effects of QYD against Cd-induced prostatic deficits. Method: Rat model of prostatic deficits was induced by 0.2 mg/kg/d CdCl2 subcutaneous injection for 15 days. The prostatic oxidative stress was evaluated by detecting the levels of malondialdehyde, nitric oxide, reduced/ oxidized glutathione, total sulfhydryl groups and enzymatic antioxidant status. The prostatic inflammation was estimated by testing the levels of pro-inflammatory cytokines. The levels of epithelial-mesenchymal transition (EMT) markers E-cadherin, fibronectin, vimentin and α-smooth muscle actin were measured by qPCR analysis. Additionally, the prostatic expressions of transforming growth factor-β1 (TGF-β1), type I TGF-β receptor (TGF-βRI), Smad2, phosphorylation-Smad2 (p-Smad2), Smad3, p-Smad3, Smad7, nuclear related factor-2 (Nrf-2), heme oxygenase-1 (HO-1), B-cell CLL/lymphoma (Bcl)-2 and Bcl-2-associated X protein (Bax) were measured by western blot assay. Results: It was found that QYD ameliorated the Cd-induced prostatic oxidative stress and inflammation, attenuated prostatic EMT, inhibited the TGF-β1/Smad pathway, increased Bcl-2/Bax ratio and enhanced the activity of Nrf-2/HO-1 pathway. Conclusion: These results showed that QYD could ameliorate Cd-induced prostatic deficits via modulating Nrf-2/HO-1 and TGF-β1/Smad pathways

Constitutive Expression of miR408 Improves Biomass and Seed Yield in Arabidopsis

miR408 is highly conserved among different plant species and targets transcripts encoding copper-binding proteins. The function of miR408 in reproductive development remains largely unclear despite it being known to play important roles during vegetative development in Arabidopsis. Here, we show that transgenic Arabidopsis plants overexpressing MIR408 have altered morphology including significantly increased leaf area, petiole length, plant height, flower size, and silique length, resulting in enhanced biomass and seed yield. The increase in plant size was primarily due to cell expansion rather than cell proliferation, and was consistent with higher levels of myosin gene expression and gibberellic acid (GA) measured in transgenic plants. In addition, photosynthetic rate was significantly increased in the MIR408-overexpressing plants, as manifested by higher levels of chloroplastic copper content and plastocyanin (PC) expression. In contrast, overexpression of miR408-regulated targets, Plantacyanin and Laccase 13, resulted in reduced biomass production and seed yield. RNA-sequencing revealed that genes involved in primary metabolism and stress response were preferentially enriched in the genes upregulated in MIR408-overexpressing plants. These results indicate that miR408 plays an important role in regulating biomass and seed yield and that MIR408 may be a potential candidate gene involved in the domestication of agricultural crops

Upregulation of miR-181c inhibits chemoresistance by targeting ST8SIA4 in chronic myelocytic leukemia

Chemotherapy resistance frequently drives tumor progression. Increased expression of ST8SIA4 has been reported in diverse carcinomas and highly correlates with leukemia multidrug resistance (MDR). MicroRNAs (miRNA) are widely recognized as key players in cancer progression and drug resistance. Here, to explore whether miRNA modulates the sensitivity of chronic myelocytic leukemia (CML) to chemotherapeutic agents and regulates ST8SIA4 expression, we analyzed the complete miRNA expression profile and found a subset of miRNAs specifically dysregulated in adriamycin-resistant CML cell line K562/ADR and its parent cell line K562. Compared with three pairs of CML cell lines and 38 clinical samples of peripheral blood mononuclear cells (PBMC) of CML patients, miR-181c expression was down-regulated in drug-resistant cell lines and CML/MDR samples. Altered expression levels of miR-181c influenced the MDR phenotypes of K562 and K562/ADR. Reporter-gene assay showed that miR-181c directly targeted and inhibited the ST8SIA4 expression, as well as miR-181c was inversely correlated with the levels of ST8SIA4 expression in CML cell lines and samples. Moreover, ST8SIA4 could reverse the effect of miR-181c on drug resistance in K562 and K562/ADR cells in vitro. Upregulation of miR-181c sensitized K562/ADR cells to adriamycin in vivo through directly suppressing ST8SIA4 expression. Further investigation showed that miR-181c mediated the activity of phosphoinositide-3 kinase (PI3K)/AKT signal pathway, and inhibition of PI3K/Akt in K562 cells counteracted miR-181c-mediated MDR phenotype. These data revealed an important role for miR-181c in the regulation of chemoresistance in CML, and suggested the potential application of miR-181c in drug resistance treatment

MiR-493-5p attenuates the invasiveness and tumorigenicity in human breast cancer by targeting FUT4

Breast cancer is a leading cause of cancer-related mortality among women. Altered fucosylation was found to be closely associated with tumorigenesis and metastasis of breast cancer. MicroRNAs (miRNAs) are important regulators of cell proliferation and metastasis, and aberrant miRNA expression has been observed in breast cancer. The present study aimed to evaluate the level of fucosyltransferase IV (FUT4) and miR-493-5p in breast cancer and investigate their relationship. In the present study, we demonstrated the differential expressional profiles of FUT4 and miR‑493-5p in 29 clinical breast cancer tissues, matched adjacent tissue samples and two breast carcinoma cell lines (MCF-7 and MDA-MB-231). Briefly, altered expression levels of FUT4 modified the invasive activities and tumorigenicity of the MCF-7 and MDA-MB-231 cells. Further study demonstrated that miR-493-5p plays a role as a suppressor in breast cancer cell invasion and tumorigenicity. Moreover, the expression levels of miR-493-5p were inversely proportional to those of FUT4 both at the mRNA and protein levels. Luciferase reporter assays confirmed that miR‑493-5p bound to the 3'-untranslated (3'-UTR) region of FUT4, and inhibited the expression of FUT4 in breast cancer cells. Taken together, our data suggest that FUT4 may have a potential role in the treatment of breast cancer, as well as miR-493-5p is a novel regulator of invasiveness and tumorigenicity of breast cancer cells through targeting FUT4. The miR-493-5p/FUT4 pathway has therapeutic potential in breast cancer

Comprehensive N-glycan profiles of hepatocellular carcinoma reveal association of fucosylation with tumor progression and regulation of FUT8 by microRNAs

Glycosylation has significant effects on cancer progression. Fucosylation is one of the most important glycosylation events involved in hepatocellular carcinoma (HCC). Here, we compared N-glycan profiles of liver tumor tissues and adjacent tissues of 27 HCC patients to reveal the association between fucosylation and HCC progression, as well as verified the potential role of miRNA in regulating fucosylation. Mass spectrometry (MS) analysis showed pronounced differences of the N-glycosylation patterns and fucosylated N-glycans between the adjacent and tumor tissues. Different fucosyltransferase (FUT) genes were also identified in adjacent and tumor tissues, and two HCC cell lines with different metastatic potential. High-level expression of FUT8 was detected in tumor tissues and highly metastatic HCC cells. Altered levels of FUT8 in HCC cell lines significantly linked to the malignant behaviors of proliferation and invasion in vitro. Furthermore, using microRNA array, we identified FUT8 as one of the miR-26a, miR-34a and miR-146a-targeted genes. An inverse correlation was revealed between the expression levels of FUT8 and these miRNAs. Luciferase reporter assay demonstrated these miRNAs specifically interacted with the 3′UTR of FUT8 and subsequently down-regulated FUT8 expression-level. The forced expression of these miRNAs was able to induce a decrease in FUT8 levels and thereby to suppress HCC cells progression. Altogether, our results indicate that fucosylated N-glycan and FUT8 levels can be used as markers for evaluating HCC progression, as well as miRNAs may be involved in inhibition of fucosylation machinery through targeting FUT8

Boosting CO2 electroreduction to multicarbon products via tuning of the copper surface charge

Electrochemical CO2 reduction (ECR) to multicarbon compounds holds great potential but remains plagued with large overpotential, low Faradaic efficiency (FE), and debilitating competition from the evolution of hydrogen and the C1 product. The design and development of advanced catalytic systems is required to overcome these problems. Here, we demonstrate the selective cathodic CO2 conversion to C2+ chemicals (C2H4, C2H5OH, and n-C3H7OH) by optimizing the surface charge of Cu via fine-tuned annealing of CuSiO3@SiO2. Stabilization of Cu+ by forming Cu–O–Si bonds is attained, as predicted by density functional theory (DFT) calculations and evidenced by multiple experiments. The C2+ selectivity is readily regulated by adjusting the surface content of Cu+, underpinning its significance during the ECR. The resulting Cuδ+@SiO2 with a Cu0-to-Cu+ surface ratio of ∼0.5 achieves a remarkable C2+ FE as high as ∼70%, C2+ partial geometric current density of about 9 mA cm–2, and large C2+-to-C1 ratio of ∼10, using an H-type cell in aqueous CsBr electrolytes at mild overpotentials. The high C2+ FE and current density persist over 12 h of continuous CO2 electrolysis. In addition, a respectable C2+ FE of ∼52% can still be attained even at a large current density (500 mA cm–2) in a flow reactor system. DFT computations reveal that the oxidized copper species Cu+ boosts C–C coupling by lessening the formation energy of the critical *OCCOH intermediate. This work underscores the prominent role of the support–catalyst interaction and the modulation of Cu oxidation states in steering the ECR selectivity