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Background: DNA methylation is one of the best characterized epigenetic modifications in the mammalian nuclear genome and is known to play a significant role in various biological processes. Nonetheless, the presence of 5-methylcytosine (5mC) in mitochondrial DNA remains controversial, as data ranging from the lack of 5mC to very extensive 5mC have been reported. Results: By conducting comprehensive bioinformatic analyses of both published and our own data, we reveal that previous observations of extensive and strand-biased mtDNA-5mC are likely artifacts due to a combination of factors including inefficient bisulfite conversion, extremely low sequencing reads in the L strand, and interference from nuclear mitochondrial DNA sequences (NUMTs). To reduce false positive mtDNA-5mC signals, we establish an optimized procedure for library preparation and data analysis of bisulfite sequencing. Leveraging our modified workflow, we demonstrate an even distribution of 5mC signals across the mtDNA and an average methylation level ranging from 0.19% to 0.67% in both cell lines and primary cells, which is indistinguishable from the background noise. Conclusions: We have developed a framework for analyzing mtDNA-5mC through bisulfite sequencing, which enables us to present multiple lines of evidence for the lack of extensive 5mC in mammalian mtDNA. We assert that the data available to date do not support the reported presence of mtDNA-5mC. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced plastic (CFRP) and titanium alloy (Ti) in a stacked structure have been widely applied in aerospace industry. Due to disparate mechanical and physical properties of CFRP and Ti, it is difficult to achieve high-quality holes and low tool wear, by drilling CFRP/Ti stacks by single-shot, even though this process exhibits high productivity in the industrial practice. In this study, for the first time, ultrasonic vibration was applied in drilling CFRP/Ti stacks by single-shot under dry condition, and its feasibility was evaluated. First, the separated cutting mode of ultrasonic-assisted drilling (UAD) was analyzed based on kinematics. Second, an experimental platform was set up, where several output parameters, during UAD of CFRP/Ti stacks, were monitored, including thrust force and torque, the interface temperature, hole accuracy, hole surface integrity, Ti chip morphologies, and tool wear conditions. Experimental results indicated that, compared to conventional drilling (CD), average thrust force and torque in UAD of CFRP decreased by 41.2 to 46.8% and 36.2 to 48.9%, respectively, and thrust force and torque in UAD of Ti decreased by 15.2 to 26.1% and 21.4 to 29.0%, respectively. Lower maximum CFRP/Ti interface temperature (353.4 °C vs. 468.1 °C) was achieved in UAD. Besides, both hole diameter accuracy and hole surface quality were significantly improved in UAD. Also, both narrow sectional ribbon Ti chips and separated Ti chips were observed in UAD, while serrated continuous ribbon Ti chips were obtained in CD. In addition, tool wear conditions in UAD were also significantly alleviated. [ABSTRACT FROM AUTHOR]

We have first obtained the direct electrochemistry of D-amino acid oxidase with a polyethylenimine modified pyrolytic graphite electrode and the electrochemical response related to the catalytic reaction to the substrates. Further studies reveal that the enzyme may exhibit different substrate specificity. Taking D-serine as a model, we have also presented an electrochemical method to detect this amino acid and have studied the effect of hydrogen peroxide on the catalytic activity of this enzyme. It is found that hydrogen peroxide can lower the enzymatic activity of this enzyme. [ABSTRACT FROM AUTHOR]

• The cutting temperature characteristics in both UAD and CD of CFRP/Ti stacks are comparatively observed. • The interface temperature in UAD of CFRP/Ti stacks is measured for the first time. • The evolution and distribution of the interface temperature are observed and compared in both UAD and CD. • The effect of process parameters on the interface temperature in either UAD or CD is revealed. • The influence of interface temperature on the surface integrity of CFRP holes is comprehensively discussed. Carbon fiber reinforced plastics (CFRP) /Titanium alloy (Ti) stacks are being extensively applied in aerospace area for superior mechanical properties. During drilling of CFRP/Ti stacks, irreparable thermal damage in CFRP at the stack interface can be easily induced by high interface temperature. This paper contributes to scientific understandings of cutting temperature characteristics, heat dissipation and resulting surface integrity in CFRP at the stack interface in both Ultrasonic Assisted Drilling (UAD) and Conventional Drilling (CD) of CFRP/Ti stacks. Results show that, similar to cutting temperature characteristics, a sudden drop of interface temperature occurs in UAD rather than a slight increase in CD. Compared with CD, the maximum interface temperature and duration of temperature beyond the glass transition temperature at stack interface in UAD are reduced by about 22.8% and 52.2% at n = 1000 rpm and f = 5 μm/rev respectively. With the aid of those findings, the relationships between temperature distribution in CFRP at the stack interface and drilling parameters have been discovered and temperature effects on CFRP hole exit damages have been elucidated. The findings of this paper can contribute to identifying the heat affected zone of CFRP and providing guidance for industrial practice to reduce the negative temperature effect in drilling of CFRP/Ti stacks. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we report a non-PCR-based electrochemical assay that can detect telomerase activity. Telomerase from HeLa cells may induce telomerization of thiolated primers immobilized on a gold electrode surface. With the telomerization reaction, more and more guanine-rich telomeric repeats are formed, so the electrochemical oxidation signal of guanine at about 1.00V, which is utilized to indicate the elongated guanine-rich telomeric repeats tethered to the primers, will be increased. This assay method can detect the telomerase activity originated from 3000 HeLa cells and thus holds promise as a simple and sensitive approach in clinical diagnosis of cancer. [Copyright &y& Elsevier]

Abstract Fiber reinforced composite laminates have been increasingly replacing conventional materials in various manufacturing sectors due to their extremely superior mechanical properties. Usually, mechanical drilling is an important final manufacturing process for composite laminates, whereas drilling of high-strength composite laminates is very challenging and difficult. As the most undesirable damage and challenging failure mode, drilling-induced delamination for fiber reinforced composite laminates is a hot research area of immerse engineering importance. A review on the path towards delamination-free drilling for composite laminates can significantly help researchers improve currently-available cost-effective drilling process and develop high performance drilling process. This review paper summarizes an up-to-date progress in drilling-induced delamination for composite laminates reported in the literature. It covers delamination formation mechanism, delamination quantification methodologies and measurement technologies, delamination suppression strategies (including tool design optimization, drilling conditions optimization and high performance drilling methods). This general review of drilling-induced delamination for composite laminates can be referenced as not only a summary of the current results from literature survey but also future work possibilities, giving the researchers the opportunity to deepen specific aspects and explore new aspects for reaching delamination-free drilling for composite laminates. [ABSTRACT FROM AUTHOR]

The properties of the support have profound effects on the catalytic performance of the supported catalyst. A series of NiMo bimetallic catalysts supported on niobium phosphate supports with different structures via the impregnation method was prepared. The effect of the acidity and porosity of the support on the dispersity and valence state of metal components and the synergistic interaction between Ni and Mo were investigated using XRD, N2-physisorption, NH3-TPD, XPS, H2-TPR, and TEM. The catalytic performance of the catalysts was evaluated in the hydrodeoxygenation of oleic acid (OA). The results demonstrate that the stronger acidity of the support leads to better dispersion of the metal Ni and it is more difficult to reduce the metal Ni. It was shown that the synergistic interaction between Ni and Mo, which could increase the concentration of oxygen vacancies (Ov) in the catalyst and the charge density on the surface of Ni atoms, is the main reason for the catalyst showing high selectivity to n-octadecane (C18). The reaction results showed that the highest selectivity to C18 (91.3%) could be achieved with 98.4% conversion of oleic acid over the Ni2Mo/NbP-3 catalyst under the condition of reaction temperature of 260 °C, 3 MPa initial H2 pressure, and reaction time of 7 h. [ABSTRACT FROM AUTHOR]

[Display omitted] • A strengthening-machining integrated ultrasonic peening drilling (UPD) was proposed. • The strengthening mechanism for UPD for Ti-6Al-4V was revealed. • The depth of subsurface plastic deformation is increased by 4 times by UPD. • The residual stress and the micro-hardness were greatly increased by UPD. • Smoother machined surface and narrower dimensional tolerance were obtained by UPD. In aircraft assembly filed, introducing compressive residual stress by cold expansion around the fastening hole is considered as a common method to enhance hole fatigue resistance. However, the conventional cold expansion technology inevitably extends the processing cycle of fastening hole. Therefore, this study proposes a strengthening and machining integrated ultrasonic peening drilling (UPD) to solve this problem by introducing ultrasonic vibration perpendicular to the hole surface during drilling. Both the strengthening principle and dimension accuracy improvement mechanism in UPD were analyzed to better understand the cutting mechanism. The feasibility experiments of UPD of Ti-6Al-4V were conducted to evaluate surface integrity and machining accuracy. The results show that compared to conventional drilling (CD), smoother machined surface and narrower dimensional tolerance were obtained with UPD. Moreover, the subsurface plastic deformation was increased by as high as 4 times with severer deformation degree. Accordingly, the surface residual stress and the depth of circumferential residual stress in the subsurface was increased by 115.7% and 125% respectively. In addition, surface micro-hardness and subsurface hardening layer depth were also significantly increased. The results demonstrated that UPD achieved the integration of strengthening and precision-machining and could be a promising method for finish drilling of aircraft fastening holes. [ABSTRACT FROM AUTHOR]

Peroxynitrite (ONOO-), which is usually generated as a response of the immune system or in inflammatory processes, is a powerful oxidant species, while hemoglobin is an important peroxynitrite scavenger in vivo. In this work, we have studied the interaction between peroxynitrite and hemoglobin through an electrochemical method and UV-Vis spectroscopy. It is found that peroxynitrite, at a relatively high concentration level, may make the protein exhibit a concentration-dependent increase of its catalytic activity towards hydrogen peroxide, whereas peroxynitrite at low concentration will result in the slight decrease of the catalytic activity. Further studies reveal that the diversification of the enzymatic activity is ascribed to the different extent of tyrosine nitration and, accordingly, the spatial conformation of the protein. [ABSTRACT FROM AUTHOR]

• Pomelo peel was used as an N-enriched biomass precursor to synthetic CO 2 adsorbent, the highest N content was 5.98 at%. • The effects of micropore structure parameters and N functional group on CO 2 adsorption properties were studied. • PPC-4 exhibited the best CO 2 adsorption performance, reaching 3.01 mmol g−1, and excellent adsorption selectivity of 38. • The adsorbents showed a decrease in adsorption capacity of <1% within five cycles, highlighting suitability for repeated adsorption–desorption processes. Recycling biomass to prepare CO 2 adsorbent has been emphasized due to the benefits such as easy availability of materials, green and sustainable. Furthermore, functional groups containing nitrogen can promote the capacity of biochar to adsorb CO 2. Usually, the production of N-doped porous carbon involves the chemical addition of amines or compounds containing nitrogen, which leads to pore blockage. For this reason, pomelo peel was used as a nitrogen-rich precursor of biomass to achieve nitrogen self-doping in this paper, and ZnCl 2 was uniformly loaded as an activator using the impregnation method. After carbonization at 800 ℃ and template removal, an efficient porous carbon adsorbent was obtained without adding extra nitrogen sources. The N content of the biocarbon was retained from 2.60 to 5.98 at% employing pre-carbonation. We also systematically analyzed the modification of the CO 2 adsorption effect by ultra-microporous structure and N atom doping. The former content showed almost no linear correlation with the adsorption data, but rather a synergistic effect with N content influenced the adsorption results under environmental conditions. The optimal adsorption of CO 2 was 3.01 mmol g−1 (25 °C, 1 bar) and 4.83 mmol g−1 (0 °C, 1 bar). In addition, the adsorbent PPC-4 has excellent CO 2 /N 2 adsorption selectivity of 38 and cyclic adsorption performance. [ABSTRACT FROM AUTHOR]

As a superior hole manufacturing process, rotary ultrasonic elliptical machining (RUEM) has been successfully employed for drilling carbon fiber reinforced plastics (CFRPs) recently. The delamination of CFRP during drilling is generally considered as the most undesirable form of damage and the most challenging failure mode. In order to reduce the delamination in this novel process, it is important to understand the formation and suppression mechanisms during RUEM of CFRP. In this study, the delamination formation in both core drilling (CD) and RUEM was observed and analyzed. The variation trend of delamination factor with feed speed as well as cutting speed was obtained. The experimental results show that, compared with CD, RUEM method can effectively reduce hole exit delamination by 5.4%–19.3% between 1/2 plies and 0.7%–8.4% between 2/3 plies at the feed rates from 50 to 100 μm/rev. Moreover, the delamination suppression mechanism in RUEM was fully analyzed and verified. In a word, in the industry practice, RUEM can be considered as a competitive and promising technique to drill CFRP compared to other delamination suppression techniques. [ABSTRACT FROM AUTHOR]

• An improved algorithm is proposed to the bovine cortical bone VAD optimization. • The fluctuation mechanism is applicable to HMCR, PAR, and BW. • The deviation is within 7.63%, and the thrust force decreased by 26.5%–33.2%. • The optimized VAD thrust force decreased by 20.19%. In orthopedics and surgery, bone drilling is an important operation. Increasing demands call for bone drilling force prediction and minimization. Vibration-assisted drilling (VAD) provides an opportunity to reduce the force. In the study, the information feedback self-adaptive harmony search (IFSHS) algorithm is presented for the thrust force minimization in bovine cortical bone VAD. The IFSHS improves the drilling parameters which leads to the optimal cutting state. The dynamic searching parameters, optimization parameters evaluation, and evaluation information feedback are applied to search the optimal solution. This force model was developed and employed with IFSHS. The VAD drilling experiments and parameters analysis are carried out. Experimental results have shown that the VAD has the potential to reduce the thrust force. Compared with conventional drilling (CD), the thrust force decreased by 18.4%–33.2% under suitable VAD parameters. Compared with the results of the original VAD parameters, the optimized thrust force decreased by 20.19%. [ABSTRACT FROM AUTHOR]

Small-diameter CFRP holes have a number of applications such as aerospace structures, circuit boards and rehabilitation medical equipments. High quality hole-making technology for the small-diameter CFRP holes is urgently needed due to various mechanical damages in twist drilling and chip removal clog in core drilling. In order to improve the hole quality, rotary ultrasonic helical machining (RUHM) was developed for machining small-diameter CFRP holes in this paper. The trajectory of cutting edge in RUHM was modelled and the intermittent cutting mode in RUHM was analyzed. Afterwards, the comparison experiments were conducted between RUHM and conventional grinding (CG). The results shows that compared to CG, both thrust force and transverse force were remarkably reduced in RUHM with a maximum decrement of 71.3% and 61.5%, respectively. Meanwhile, both the hole edge quality and surface integrity were significantly improved in RUHM. Compared to CG, delamination factor at hole exit was reduced by 12.8–25.7% and surface roughness for hole inner surface was reduced by 51.9%–53.2% for Ra value in RUHM. Moreover, the mechanisms of cutting force reduction, delamination formation and suppression, and surface roughness improvement in RUHM were also analyzed. The results suggest that RUHM is a promising processing strategy for machining small-diameter CFRP holes. [ABSTRACT FROM AUTHOR]

Ultrasonic assisted milling (UAM) has been demonstrated excellent cutting performance for nickel-based superalloy machining. However, the machining quality improvement achieved by traditional UAM is limited at high cutting speed. Rotary ultrasonic elliptical milling (RUEM) is an unconventional cutting method recently proposed for high quality and efficient machining of difficult-to-cut alloy, breaking the cutting speed limit for UAM. In order to verify the feasibility of this method in thin-walled curved surface machining, the ball end milling cutter was adopted in feasibility experiments of RUEM on Inconel 718 with the evaluation of cutting force, surface integrity and tool wear. The results indicate that compared with conventional milling (CM) without ultrasonic vibration assistance, the cutting force reduction reaches 31.33% in RUEM. The material strength enhancement was obtained in RUEM with the disturbed strengthening phases of Inconel 718. RUEM achieved − 728.65 MPa of surface compressive residual stress and 140 µm depth of compressive residual stress layer beneath the machined surface simultaneously, while CM provided tensile residual stress field near the machined surface. Moreover, the tool flank wear status was significantly improved in RUEM. These results demonstrate that various machinability benefits of Inconel 718 are obtained by RUEM, which is a promising method for nickel-based superalloy thin-walled structure finish machining. [ABSTRACT FROM AUTHOR]

Malignant gliomas invariably recur after irradiation, showing radioresistance. Meanwhile, cranial irradiation can bring some risk for developing cognitive dysfunction. There is increasing evidence that cytokines play their peculiar roles in these processes. On the one hand, cytokines directly influence the progression of malignant glioma, promoting or suppressing tumor progression. On the other hand, cytokines indirectly contribute to the immunologic response against gliomas, exhibiting pro-inflammatory or immunosuppressive activities. We propose that cytokines are not simply unregulated products from tumor cells or immune cells, but mediators finely adjust the balance between glioma cells and tumor microenvironment after irradiation. The paper, therefore, focuses on the changes of cytokines after irradiation, analyzing how these mediate the response of tumor cells and normal cells to irradiation. In addition, cytokine-based immunotherapeutic strategies, accompanied with irradiation, for the treatment of gliomas are also discussed. [ABSTRACT FROM AUTHOR]

Vibration-assisted machining (VAM) is implemented in titanium alloy processing to solve some challenges, such as difficulty in chip breaking, large cutting forces, and high cutting temperatures. Based on the multi-region dynamic angles and the double-side wedge angle deformation mechanism, this study improves the vibration-assisted drilling (VAD) cutting forces and chip breaking model. The dynamic kinematics angles, the behavior of parameter influence, and the cutting strain effect of intermittent VAM are analyzed. VAD and conventional drilling (CD) experiments are carried out for model validation and mechanism analysis. The experiments show that the maximum deviation of the drilling forces simulation value and the experimental value is 9.13 %. Compared with the CD, the cutting force of the VAD is decreased by 10.1 %–46.2 %. The dynamic feed angle causes multiple cutting angles fluctuations, which affects cutting performance. The adjustment of the VAD cutting parameter value could reduce the chip length by 26.6 %–43.9 %. Material cutting strain presents multi-region characteristic, which influences the chip morphology. This study provides a reference for VAM parameter optimization. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration has received widespread attention for its dramatic effect on grain refinement and microstructure modification during casting, additive manufacturing, cold rolling, and cutting, changes which can significantly improve the mechanical and physical properties of components. As a novel ultrasonic vibration cutting method, rotary ultrasonic elliptical milling (RUEM) has been introduced to mill the alloy Ti-6Al-4V. However, the effects of ultrasonic elliptical vibration on the microstructures of machined surfaces in end milling of Ti-6Al-4V are still unclear. A comprehensive study on the surface characteristics and sub-surface microstructure in RUEM of Ti-6Al-4V was conducted. The results show that the uniform textures, in the form of ridges mapped on the machined surface in RUEM, varied with the cutting speed. Compared with conventional milling, microchip debris adhesion on the machined surface was significantly reduced by using RUEM. Moreover, intense plastic deformation in the sub-surface was obtained, and nanocrystalline layers, with grain dimensions of 10 nm to 100 nm, were fabricated on the processed surfaces of RUEM. Additionally, the improvement in sub-surface microstructure increased the surface micro-hardness from 21.22% to 33.84%. This study allows an in-depth understanding of sub-surface deformation and surface nanocrystallization in RUEM of Ti–6Al–4V. Unlabelled Image • The effects of RUEM on machined surface morphology and surface defects are obtained. • The mechanism of microstructure evolution in the machined surface of RUEM is investigated. • The influence of RUEM on the surface nanocrystallization of Ti-6Al-4V is analyzed. [ABSTRACT FROM AUTHOR]

Titanium alloys have been applied in aerospace, biomedical, and chemical industries due to their superior mechanical properties. As a novel machining method, rotary ultrasonic elliptical machining has been successfully introduced into high-speed side milling of Ti–6Al–4V recently. However, the surface integrity in end milling of titanium alloy using this method is still unclear. In this study, a comprehensive experiment on surface integrity in rotary ultrasonic elliptical end milling of Ti–6Al–4V was conducted at various vibration amplitudes and cutting speeds. Results show that regular substantial micro-vibration textures in the form of separated ridges are obtained on the machined surfaces in RUEEM. Surface roughness values rise from Ra 0.160 μm to Ra 0.758 μm with the increasing cutting speed and vibration amplitude. Both the thickness of subsurface deformed layer and the value of surface micro-hardness increase with rising amplitude at low cutting speeds, while the hardening effect gradually weakens as the cutting speed increases to 160 m/min. Besides, the values of surface compressive residual stress gradually decrease with vibration amplitudes at low cutting speeds, while opposite trends show at the high cutting speed (160 m/min). This study can provide a new method for the effective control of the surface integrity for high-speed end milling of titanium alloy. Image 1 • Rotary ultrasonic elliptical machining is introduced to high-speed end milling of Ti6Al4V for the first time. • The effect of vibration on surface integrity in rotary ultrasonic elliptical end milling (RUEEM) of Ti6Al4V is studied. • The effect of cutting speed from 40 m/min to 160 m/min on surface integrity in RUEEM is experimental investigated. [ABSTRACT FROM AUTHOR]