Effects of honing treatment on AIP-TiN and TiAlN coated end-mill for high speed machining

The objective of this work is to compare the tool performance of TiN and TiA1N coated carbides end-mills deposited by an arc ion plating （ALP） method, using honing treatment to polish the cutting edge surface sleekly. The curve of surface roughness versus honing time showed a rapid improvement initially and thereafter became steady, manifesting a saturation effect. The optimal honing time related to surface roughness was determined to be approximately 20 s. As the surface roughness increased, the critical loads reduced. At an average surface roughness （Ra） of 0.028 p.m, the highest critical loads of TiN and TiAlN coating layers were 98 and 114 N, respectively. Tool performances of uncoated and coated tools were conducted under high speed machining （HSM） of AISI D2 cold-worked die steel （62 HRC）. Consequently, the TiAlN coated end-mill using honing treatment showed excellent tool life under HSM conditions.

Formation of nanocrystalline microstructure in arc ion plated CrN films

Applying negative bias voltages caused significant microstructure changes in arc ion plated CrN films. Nanocrystalline microstructures were obtained by adjusting the negative bias voltage. Structural characterizations of the films were carried out using X-ray diffractometry (XRD) and high-resolution transmission electron microscopy (HR-TEM). The results indicated that increasing ion bombardment by applying negative bias voltages resulted in the formation of defects in the CrN films, inducing microstructure evolution from micro-columnar to nanocrystalline. The microhardness and residual stresses of the films were also affected. Based on the experimental results, the evolution mechanisms of the film microstructure and properties were discussed by considering ion bombardment effects.

New insights into carbon-based and MXene anodes for Na and K-ion storage: A review

Na-ion batteries and K-ion batteries are promising alternatives to vastly used lithium-ion batteries mainly due to the larger natural abundance of sodium and potassium resources. Carbon-based and MXene materials have received increasing attention due to their unique layered structure to accommodate the larger sodium and potassium ions. It’s proposed that ionic size disparity (K^(+): 1.38 Å;Na^(+): 0.97 Å;Li^(+): 0.76 Å) leads to sluggish intercalation and extraction kinetics in larger alkali metal ions (AMIs). Nevertheless, the electrochemical inactivity of sodium intercalation in graphite suggests that different chemical properties of AMs and their interactions with carbon host and electrolytes is crucial for interfacial instability and irreversible capacity loss. Structural modifications by expanding interlayer spacing and defect engineering enable reduced diffusion barriers and enhanced insertion of sodium or potassium, but it blurs the electrochemical performance between battery and capacitor. This review provides insight into 2D carbon materials and their architectures for Na and K-ion batteries through an in-depth analysis of structure–property interdependence and different electrochemical mechanisms supported by both experimental and theoretical data to discuss the promises and challenges of post-lithium batteries. Finally, the perspectives and potential directions regarding material design concepts for 2D carbon-based nanomaterials and MXene phases for metal-ion storage are proposed.

Effect of carbon on microstructure of CrAlC_xN_(1-x) coatings by hybrid coating system

A systematic investigation of the microstructure of CrA1CxN1-x coatings as a function of carbon contents was conducted. Quaternary CrA1CxN1-x coatings were deposited on Si wafers by a hybrid coating system combining an arc-ion plating technique and a DC reactive magnetron sputtering technique using Cr and AI targets in the Ar/N2/CH4 gaseous mixture. The effect of carbon content on microstructure of CrA1C^N~ x coatings was investigated with instrumental analyses of X-ray diffraction, X-ray photoelectron, and high-resolution transmission electron microscopy. The results show that the carbon content of CrA1CxN1-x coatings linearly increases with increasing CH4/（CH4/N2） gas flow rate ratio. The surface roughness of the CrA1CxN1-x coating layer decreases with the increase of carbon content.

Internal modification in transparent hybrid germanium-silica plates using plasma formation induced by a femtosecond laser

The fabrication of an internal diffraction grating with photoinduced refractive index modification in planar hybrid germanium-silica plates was demonstrated using low-density plasma formation excited by a high-intensity femtosecond (150 fs) Ti:sapphire laser (λp=790 nm).The refractive index modifications with diameters ranging from 400 nm to 3 μm were photoinduced after plasma formation occurred upon irradiation with peak intensities of more than 2×1013 W/cm2.The graded refractive index profile was fabricated to be a symmetric around from the center of the point at which low-density plasma occurred.

Material properties and machining performance of hybrid Ti_2AlN bulk material for micro electrical discharge machining

Mn+1AXn(MAX) phases are a family of nanolaminated compounds that possess unique combination of typical ceramic properties and typical metallic properties.As a member of MAX phase,Ti2 AlN bulk materials are attractive for some high-temperature applications.The synthesis,characteristics and machining performance of hybrid Ti2 AlN bulk materials were focused on in this work.The bulk samples mainly consisting of Ti2 AlN MAX phase with density close to theoretic one were synthesized by a spark plasma sintering method.Scanning electron microscopy results indicate homogenous distribution of Ti2 AlN grains in the samples.Micro-hardness values are almost constant under different loads (6-6.5 GPa).A machining test was carried out to compare the effect of material properties on micro-electrical discharge machining (micro-EDM) performance for Ti2 AlN bulk samples and Ti6242 alloy.The machining performance of the Ti2 AlN sample is better than that of the Ti6242 alloy.The inherent mechanism was discussed by considering their electrical and thermal conductivity.

Distribution of electric field for carbon nanotube assembly: Simulation (I)

The distribution of electric field for the alignment and attachment of carbon nanotubes (CNTs) was simulated. To be attached at the desired place, the aligned and attracted CNTs should be stayed in the desired area called the stable region or the quasi-stable region for an instant where the change of electric field is minimized. Since the conical electrode has the very narrow sized quasi-stable region, few CNTs can be attached. The rectangular electrodes have a wide stable region, so lots of CNTs can be attached. The results indicate that the round electrode which has a proper sized quasi-stable region is more effective for aligning and attaching a single CNT than the conical or rectangular shaped electrodes.

Hemoglobin induces colon cancer cell proliferation by release of reactive oxygen species

AIM: To study whether hemoglobin could amplify colon cancer cell proliferation via reactive oxygen species (ROS) production. METHODS: Colon cancer cell line HT-29 was grown in the conventional method using RPMI1640 media. The viability of the cells was measured using the colorimetric MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazo- lium bromide] assay after adding hemoglobin. We de- termined reactive oxygen species levels to be indicators of oxidative stress in HT 29 cell lines with and without hemoglobin and/or 5-fluorouracil (5-FU), 5’-deoxy-5-flu- orouridine (5-DFUR) using fluorometric dichlorofluorescin diacetate (DCFH-DA) assay. RESULTS: Cellular proliferation was increased with he- moglobin in a concentration-dependent manner. A signif- icant increment on ROS levels was found in HT 29 cells following hemoglobin incubation. The cytotoxic effects of 5-FU and 5-DFUR were significantly blunted by admin- istration of hemoglobin. There was a slight increase of peroxiredoxin 1, superoxide dismutase 1 concentration according to different hemoglobin concentrations. CONCLUSION: Hemoglobin has a cellular proliferative effect on HT-29 colon cancer cell line by production of ROS. Also, hemoglobin abates cytotoxic effects of che- motherapeutic agents such as 5-FU and 5-DFUR.

Optical diffraction gratings embedded in BK-7 glass by low-density plasma formation using femtosecond laser

The optical embedded diffraction gratings with the internal refractive index modification in BK-7 glass plates were demonstrated using low-density plasma formation excited by a high-intensity femtosecond （130 fs） Ti： sapphire laser （λp=790 rim）. The refractive index modifications with diameters ranging from 400 nm to 4 gm were photoinduced after plasma formation occurred upon irradiation with peak intensities of more than 1 ×10^13 W/cm2. The graded refractive index profile was fabricated to be a symmetric around the center of the point at which low-density plasma occurred. The maximum refractive index change （An） was estimated to be 1.5x10 2. Several optical embedded gratings in BK-7 glass plate were demonstrated with refractive index modification induced by the scanning of low-density plasma formation.

Distribution of electric field for carbon nanotube assembly: Experiments (II)

The distribution effect of electric field on the alignment and attachment of carbon nanotubes （CNTs） were investigated. The experimental results were compared with the simulation results according to three different shaped electrodes. In previous simulation, the round shaped electrodes were expected to be more effective for aligning and attaching a single CNT between two electrodes than conical or rectangular shaped electrodes. To verify the simulation results, three different shaped electrodes were introduced and a single multi-walled carbon nanotube （MWNT） was attached. The optimal conditions for aligning and attaching MWNTs such as the frequency, applied voltage and concentration of MWNTs solution were investigated. Through repeated experiments, frequency of 100 kHz-10 MHz, applied voltage of 0.3-1.3 V^s/~m, concentration of 5 ktg/mL in MWNTs solution were obtained as a possible condition range to attach MWNTs. Under these conditions, the yield of MWNTs attachment between two electrodes was up to 70%. In previous simulation, furthermore, it was verified that the size of the stable or quasi-stable region made CNTs aligned and attached on different shaped electrodes from the comparison of the experimental and simulation results. Most single MWNT attachment was accomplished on the round shaped electrodes.

Environmentally friendly hybrid coating prepared by electro-deposition method at various seawater conditions

The formation mechanism of calcareous deposit films in seawater involves an increase in pH at the metal/solution interface due to cathodic reactions, a raised carbonate ion concentration at the interface and precipitation of inorganic deposits such as CaCO3, Mg(OH)2. Environmentally friendly hybrid calcareous deposit films were formed by an electrochemical technique on steel substrates in various solution environments. And the influence of dissolved gas on formation of calcareous deposit films was investigated by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray diffractometry(XRD). Consequently, these results showed that formation of good overall calcareous deposited films by dissolved gas in seawater environments can be achieved by controlling the material composition and structure through effective use of electrochemical method.

南朝鲜侏罗纪和三叠纪古地磁

前言东亚是研究地壳断块增生的理想天然场所。古地磁学是有效地确定相对运动量的主要手段之一。尽管古地磁研究数量迅速增加,但至今关于一些大断块,例如西伯利亚,华北或华南断块还没有足够而可靠的显生宇数据(Lin 等,1985)。虽然对西伯利亚(即欧亚)断块和中国断块之间古磁极差异的解释仍然不一致(Full 等,1987),但晚中生代的研究结果是充分的,并对于侏罗纪和更年青年代取得较一致的意见。朝鲜习惯上被认为是华北断块(中朝)的一部分,在东亚的任何构造分析中因朝鲜而造成了更多的不确定性。然而。