Several Kinds Of Materials Research Articles

Types of Polymers Using in 3D Printing and Their Applications: A Brief Review

The technology based on using 3D printing machines (3DPs) can be considered a promising approach in industry. A 3D printer might be define as machines which manufacture 3D products or models that already designed by computer aided design (CAD) software programs. These machines can create geometries that are very complicated and so difficult to fabricate by traditional manufacturing approaches. Additionally, it has capability to create items that is so complex internal design products with lower time and cost. Several kinds of materials have been applied in this technology. The polymers is one the most common materials that are using in 3D printing. This review seeks to clarify the features and benefits of different types of polymers including Acrylonitrile Butadiene Styrene (ABS), Polylactic acid (PLA), Acrylonitrile styrene acrylate (ASA), Polyethylene terephthalate (PET), Glycolized polyester(PETG), Polycarbonate (PC), Polypropylene (PP), Nylon, and Hybrid and composite materials.

Critical Advances of Aqueous Rechargeable Ammonium Ion Batteries

Aqueous rechargeable batteries have drawn wide attention owing to the advantages of low cost, high safety, and rapid kinetic process. In recent years, the use of NH4+ ions and other nonmetallic ions as carrier batteries has come into researchers’ view. The storage of NH4+ shows fast diffusion kinetics and the ability to achieve highly reversible redox processes by forming hydrogen bonds between NH4+ and electrode materials. Designing and exploration of advanced materials for NH4+ storage are of high significance in building high‐performance aqueous battery systems. This review summarizes the latest advances of critical materials, including Prussian blue analogs, transition metal oxides, and organic compounds for NH4+ batteries. Comparison of properties among different materials is discussed in detail. Different NH4+ storage behaviors according to several kinds of materials are demonstrated. Finally, the challenges and valuable perspectives for the further development of aqueous NH4+ batteries are also provided.

Promising Materials for Photocatalysis‐Self‐Fenton System: Properties, Modifications, and Applications

Photocatalysis‐self‐Fenton system (PSFs), which integrates photocatalysis with Fenton technology, is investigated thoroughly in wastewater treatment due to the virtues of no addition of H2O2 and accelerated circulation of Fe2+/Fe3+. Several kinds of materials that mainly include metal‐free graphite carbon nitride (g‐C3N4), metal oxides (Fe3O4), and metal sulfide (CdS, FeS2) have demonstrated extensive development potential. Nevertheless, most of the developed catalysts are unable to satisfy the requirements of PSFs. Therefore, a comprehensive review committed to the materials and modification methods in PSFs is put forward. First, the concrete mechanism of PSFs from two aspects of photocatalysis and Fenton reaction is discussed. Second, the properties, modifications (morphology modulation, heterojunction construction as well as doping), and applications (contaminants degradation and disinfection) of the promising catalysts are emphasized. Finally, the novel directions for future research in PSFs are looked forward to. This review opens up a new horizon for enhancing the practical application of PSFs in future.

Nonlinear Hall effects in two-dimensional moiré superlattices

The Hall effect refers to the generation of a voltage in a direction perpendicular to the applied current. Since its discovery in 1879, the Hall effect family has become a huge group, and its in-depth study is an important topic in the field of condensed matter physics. The newly discovered nonlinear Hall effect is a new member of Hall effects. Unlike most of previous Hall effects, the nonlinear Hall effect does not need to break the time-reversal symmetry of the system but requires the spatial inversion asymmetry. Since 2015, the nonlinear Hall effect has been predicted and observed in several kinds of materials with a nonuniform distribution of the Berry curvature of energy bands. Experimentally, when a longitudinal alternating current (AC) electric field is applied, a transverse Hall voltage will be generated, with its amplitude proportional to the square of the driving current. Such a nonlinear Hall signal contains two components: one is an AC transverse voltage oscillating at twice the frequency of the driving current, and the other is a direct current (DC) signal converted from the injected current. Although the history of the nonlinear Hall effect is only a few years, its broad application prospects in fields of wireless communication, energy harvesting, and infrared detectors have been widely recognized. The main reason is that the frequency doubling and rectification of electrical signals via some nonlinear Hall effects are achieved by an inherent quantum property of the material - the Berry curvature dipole moment, and therefore do not have the thermal voltage thresholds and/or the transition time characteristic of semiconductor junctions/diodes. Unfortunately, the existence of the Berry curvature dipole moment has more stringent requirements for the lattice symmetry breaking of the system apart from the spatial inversion breaking, and the materials available are largely limited. This greatly reduces the chance to optimize the signal of the nonlinear Hall effect and limits the application and development of the nonlinear Hall effect. The rapid development of van der Waals stacking technology in recent years provides a brand new way to design, tailor and control the symmetry of lattice, and to prepare artificial moiré crystals with certain physical properties. Recently, both theoretical results and experimental studies on graphene superlattices and transition metal dichalcogenide superlattices have shown that artificial moiré superlattice materials can have larger Berry curvature dipole moments than those in natural non-moiré crystals, which has obvious advantages in generating and manipulating the nonlinear Hall effect. On the other hand, abundant strong correlation effects have been observed in two-dimensional superlattices. The study of the nonlinear Hall effect in two-dimensional moiré superlattices can not only give people a new understanding of the momentum space distribution of Berry curvatures, contributing to the realization of more stable topological transport, correlation insulating states and superfluidity states, but also expand the functional space of moiré superlattice materials which are promising for the design of new electronic and optoelectronic devices. This review paper firstly introduces the birth and development of the nonlinear Hall effect and discusses two mechanisms of the nonlinear Hall effect: the Berry curvature dipole moment and the disorder. Subsequently, this paper summaries some properties of two-dimensional moiré superlattices which are essential in realizing the nonlinear Hall effect: considerable Berry curvatures, symmetry breaking effects, strong correlation effects and tunable band structures. Next, this paper reviews theoretical and experimental progress of nonlinear Hall effects in graphene and transition metal dichalcogenides superlattices. Finally, the future research directions and potential applications of the nonlinear Hall effect based on moiré superlattice materials are prospected.

Cybersecurity using Data Mining Techniques

The study is based on the cyber security using data mining in a certain manner and all the insights have been taken from reliable resources which are related to the subject matter. At the beginning of the following article, the, the introduction has been served over the following topic of the cyber security and data mining in business. Also, in the following context, several kinds of materials and methods have been selected and evaluated to bring betterment in the study. The cross-sectional research design, inductive approach, secondary data have been selected by following the qualitative method. At the beginning, the data mining and cyber security have been represented with sheer elaboration and then the importance of data mining techniques within the business has been illustrated within a certain manner. After this, different kinds of usages of data mining techniques like detecting malwares, intrusions and virus attacks have been depicted in a certain norm of data mining techniques. Later on, the following study has been evaluated with the help of proper and authentic interpretation of the rate of cyber security within a business.

Indonesian women’s preferences regarding robe: Naisha Hijrah’s production matches future customers’ desires

The Indonesian textile industry grew by 15.35 per cent in 2019, whereas previously, it had only seen a growth of around 8.73 per cent. As a result, it occurred to the textile and apparel manufacturers that they needed to enlarge their business lines swiftly. Naisha Hijrah, a designer, producer and textile retailer, sells clothes based on Islamic styles with a post-modernist concept. This study elaborates on how Naisha Hijrah has met its customers’ needs. It also analyses why Naisha Hijrah could become the leading producer and retailer. Naisha Hijrah initially captured the Arabian clothes. This research shows that Naisha’s products have attributes that include crease-free fabric, strong seams, unnoticed fabric fibres, cut patterns, delicate stitching and a design that permits the wearer to perform their ablutions without removing the garment. On the other hand, the technical qualities include many of Naisha’s prioritized fabrics, such as Balotelli and Toyobo, accompanied by zippers designs. Therefore, Naisha develops its product that focuses on technical attributes that Indonesian women prioritize to fulfil their future desires. Finally, this study suggests that Naisha’s robes should combine several kinds of materials in each garment, improve the tailors’ skills, ensure no defects in its production and continuously push the workers to make firmer and smoother stitches. Therefore, Naisha Hijrah should increase sales because it sells what Indonesian women need and love. All this implies that it could be the leading retailer of Islamic fashion items.

Promoting Rechargeable Batteries Operated at Low Temperature.

ConspectusBuilding rechargeable batteries for subzero temperature application is highly demanding for various specific applications including electric vehicles, grid energy storage, defense/space/subsea explorations, and so forth. Commercialized nonaqueous lithium ion batteries generally adapt to a temperature above -20 °C, which cannot well meet the requirements under colder conditions. Certain improvements have been achieved with nascent materials and electrolyte systems but have mainly been restrained to discharge and within a small rate at temperatures above -40 °C. Moreover, the recharging process of batteries based on the graphite anode still faces huge challenges from the simultaneous Li+ intercalation and potential Li stripping at subzero temperatures. Revealing the temperature-dependent evolution of physicochemical and electrochemical properties will greatly benefit our understanding of the limiting factors at low temperature, which is of significant importance.Herein, we dissect the ion movements in the liquid electrolyte and solid electrode as well as their interphase to analyze the temperature effect on Li+-diffusion behavior during charging/discharging processes. An electrolyte is the vital factor, and its ionic conductivity guarantees the smooth operation of the battery. However, it is the sluggish diffusion in the solid, especially the charge transfer at the solid electrolyte/electrode interfaces (SEI), that greatly limits the kinetics at low temperature. Many strategies have been put forward to tame electrolytes for low-temperature application. From a macroscopic point of view, multiple solvents are mixed to adjust the liquid temperature range and viscosity. With respect to the microscopic nature, research is focusing on the solvation structure by formulating the ratio of Li+ ions to solvent molecules. The binding energy of the Li+-solvent complex is crucial for the desolvation process at low temperature, which is manipulated with fluorinated solvents or other weakly solvating electrolytes. On the basis of an optimized electrolyte, electrodes and their reaction mechanism need to be coupled carefully because different materials show totally different responses to temperature change. To avoid the sluggish desolvation process or slow diffusion in the bulk intercalation compounds, several kinds of materials are summarized for low temperature use. The intercalation pseudocapacitive behavior can compensate for the kinetics to some extent, and a metal anode is a good candidate for replacing a graphite anode to build high-energy-density batteries at subzero temperature. It is also a wise choice to develop nascent battery chemistry based on the co-intercalation of solvent molecules into electrodes. Furthermore, the interfacial resistance contributes a lot at low temperature, which need be modified to accelerate the Li+ diffusion across the film. This will be linked to the electrolyte, exactly speaking, the solvation structure, to regulate the organic and inorganic components as well as the structure. Although it is difficult to investigate SEI on a graphite anode owing to its poor performance at low temperature, great efforts on Li metal anodes have offered some valuable information as reference. It is worth mentioning that the improvement in low-temperature performance calls for not only a change in the single composition but also the synergetic effect of each part in the whole battery. The elementary studies covered in this account could be taken as insight into some key strategies that help advance the low-temperature battery chemistry.

LAC-UFF STATUS REPORT: CURRENT PROTOCOLS AND RECENT DEVELOPMENTS

ABSTRACTThe Radiocarbon Laboratory of the Fluminense Federal University was installed in 2009, and its NEC Single Stage Accelerator Mass Spectrometry system has been operational since 2012. As the first14C-AMS facility in Latin America, the LAC-UFF became a reference center for radiocarbon (14C) dating in Brazil. Over the years we have implemented pretreatment protocols for several kinds of materials, such as cellulose, soil, bone, and biofuels. In the present paper we describe our current protocols for the preparation of these types of samples. Moreover, after 10 years of operation, with the aim of expanding the range of materials we are able to analyze, we report the results of several tests to improve accuracy, precision and background levels. For example, here we discuss how isotopic fractionation during the graphitization and measurement steps has been controlled. Concerning results interpretation, our research group has been using OxCal chronological models to analyze different contexts such as stromatolite growth, tree rings, soil deposition and marine reservoir effect (MRE) determination.

Spatially localized measurement of isotropic and anisotropic thermophysical properties by photothermal radiometry

This work presents the development of a new photothermal radiometry (PTR) setup using a mix between frequency and spatial domain scans, along with a three-dimensional (3D) heat diffusion model. This newly developed PTR system, with a spatial resolution of 33 μm, is used to measure thermophysical properties of several kinds of materials. These properties include the thermal diffusivity, a, of homogeneous semi-infinite materials, thermal boundary resistance, Rth, and thermal anisotropy of membranes. The measured properties for homogeneous semi-infinite materials and two-layered systems are in good agreement with the literature values. In addition, it was possible to obtain an anisotropic factor of 24.6 between the in-plane and cross-plane thermal diffusivity of a 25 μm anisotropic flexible graphite sheet. Furthermore, it was also possible to measure, both directly and independently, the anisotropic thermal diffusivities for a 1 μm titanium membrane. It is suggested that this new hybrid technique can help us to fill the gap between conventional PTR and other photothermal and thermoreflectance techniques. Using this PTR setup, it is possible to experimentally measure isotropic and anisotropic thermophysical properties of bulk and thin materials, including membranes, with high precision through accurate characterization of the pump beam spots size. This is accomplished without the need for an optical transducer layer.

Targeting Burkitt Lymphoma By CAR-Extracellular Vesicles: A Tropism-Delivery Platform for CRISPR/Cas9 System

IntroductionCRISPR/Cas9 system is a highly efficient genomic editing system. However, application of CRISPR/Cas9 system in vivo is somewhat limited for delivery methods and safety concerns. Extracellular vesicles (EVs) are released by exocytosis which results in consistent surface membrane proteins with original cells and capable to deliver several kinds of materials in vivo. However, EVs can be absorbed by other organs or tissues besides tumors, leading to possible off-target effects. Therefore, it is imperative to enhance the targeting property of EVs in vivo. Recently, clinical advances have confirmed that CAR-T cells possess great tropism and multiple choices of target. This may be an effective means to improve EVs' selective accumulation in tumors. In this proof-of-principle study, we exploit the target precision of CAR to establish an EV-derived tropism-delivery platform for CRISPR/Cas9 system as a novel therapeutic strategy for malignant diseases.MethodsWe established CD19-CAR-293T cell line by CAR lentivirus transfection. Raji cells (Burkitt lymphoma) were chosen as target tumor cells for it's CD19 positive. For the isolation of EVs from CD19-CAR-293T and 293T cells, culture medium was harvested, centrifuged and filtered through 0.45μm filters to remove the dead cells and large microvesicles. Purified EVs were examined by (NTA). The plasmids of CRISPR/Cas9 system targeting human cMyc gene were constructed by standard protocols and electroporated into EVs using Gene Pulser Xcell Electroporation System (BioRad). EVs were labelled with lipophilic fluorescent dye for visualization of confocal images. Uptake of EVs in Raji cells was analyzed using confocal microscope. To observe the biodistribution of EVs, Raji-bearing xenograft NOD/SCID mice were generated. When the tumors reached 200mm3, labelled EVs were intracardially injected to mice. Biofluorescence images were obtained using IVIS imaging system.ResultsNTA showed that a size distribution of approximately 100nm to 450nm for two types of EVs (Fig. 1A). The modifications didn't affect the physical properties. We used a fixed number ratio of Raji cells to EVs in incubation to compare the uptake efficiency between normal EVs and CD19-CAR-EVs. After one hour of incubation with Raji cells, uptake efficiency of the CD19-CAR-EVs was higher than that of the normal EVs, as indicated by signal intensity in the confocal microscope images (Fig. 1B). To confirm whether CD19-CAR-EVs could target tumors in vivo, we intracardially injected the same number of labelled EVs or CD19-CAR-EVs to Raji xenograft NOD/SCID mice and observed at 0h and 24h post-injection. As results, the CD19-CAR-EVs significantly accumulated in tumor sites compared to liver, kidney and other tissues. In contrast, the normal EVs were distributed throughout the body (Fig. 1C). Ex vivo images exhibited that compared with the EV group, the CD19-CAR-EVs accumulated more in tumors and less in liver, kidney and other tissues (Fig. 1C). The tumor/whole-body fluorescence intensity ratios were calculated in the EV and CD19-CAR-EV groups (Fig. 1D). At 24h post-injected, the ratios in the CD19-CAR-EV group were higher than that in EV group (P<0.05).Twelve days after the subcutaneous xenograft models were generated, CD19-CAR-EVs loaded with CRISPR/Cas9 system targeting human cMyc were injected intracardially or intratumorally (i.t.) to mice with interval of 4 days for 5 times. Mice injected with EVs only, with plasmid of cMyc sgRNA/Cas9 only, and with Cas9 loaded CD19-CAR-EVs without sgRNA were used as control groups. Tumor sizes were compared among groups at 18 days post the first EVs injection. Tumors from intracardially injected CD19-CAR-EVs+cMyc sgRNA/Cas9 group were smaller than those from EVs+cMyc sgRNA/Cas9 group. And the tumors from intratumoral injection of CD19-CAR-EVs+cMyc sgRNA/Cas9 were the smallest ones among groups (Fig. 1E).ConclusionIn this study, we take advantages of CAR's affinity to tumor cells and EVs' delivery capacity, and generated CD19-CAR-EVs capable of delivering CRISPR/Cas9 system. This CAR-EV-derived tropism-delivery system can be administered systemically or locally and accumulated selectively in tumor tissues to achieve gene editing in vivo. With evolving repertoires of CARs and multiplex genome engineering abilities of CRISPR/Cas9, this approach is with great potential for biotechnological and therapeutic applications. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Impulsive coupling characteristics of materials irradiated by electron beam

The blow-off impulse is the condition of applied loads of the structural response induced by pulsed beam and the coupling coefficient of impulse is a key parameter to estimate the potential of producing impulse. A new kind of impulse probe was developed and tests were conducted to measure the impulses of several kinds of materials exposed to electron beam on “Flash II” accelerator. Experimental results of these tests show that:(1) when the energy fluxes are in the range of 150 ∼ 183 J·cm-2, the average coupling coefficient of blow-off impulse of the soft graphite is 0.40 Pa·s/(J·cm-2), and that of C/E is 0. 94 Pa·s/(J·cm-2). (2) as a structural material, the C/E composite has better anti-radiation performance than aluminium material because the average coupling coefficient of C/E is less than that of aluminium.

A general constitutive model of soft elastomers

It is a long-standing challenge to predict the general constitutive behaviors of soft elastomers under finite deformation, since most of the constitutive relations calibrated from uniaxial tension tests cannot accurately characterize the responses under complex deformation states. In this paper, we develop a general constitutive model of soft elastomers based on a new microscopic picture, in which the free energy is decomposed into two parts: one comes from the cross-linked network and the other from the entangled network. To calibrate and verify the proposed constitutive model, we test several kinds of materials including vulcanized rubber, natural rubber, Entec Enflex S4035A TPE, silicone rubber, and Tera-PEG gel. The results are compared with those from other similar constitutive models (extended tube model and nonaffine network model). With only three material parameters, our model not only captures the softening with a stress plateau and hardening with a sharp rise in stress, but also accurately characterizes the constitutive behaviors of soft rubberlike materials under various deformation states. As an example, we show that the model can predict well the inhomogeneous deformation of an inflated balloon diagram. This constitutive model possesses considerable advantages in the applications of soft robots, soft electronics, elastomeric transducers, etc.

A Novel NaxMO2 (M = transition metal) Cathode Material for Sodium-Ion Batteries: Insight from the Synergetic Effect of Multi-Metal Substitution

Sodium-ion batteries (SIBs), as a highly promising alternative to its counterpart lithium-ion batteries (LIBs), have attracted increasing attentions due to the low-cost and abundant sodium resources, as well as the compatibility of aluminum current collectors in anode. Due to the heavier atom and larger size of Na atom compared with Li atom, the energy density of SIBs is generally lower than that of LIBs. As a result, the main application area for SIBs would be the large energy storage systems, where cost is the crucial consideration [1]. Currently, to obtain cathode materials with good performance is a main challenge up in SIBs field, because of the relatively large size and slow diffusion of Na+. Several kinds of materials, such as layered transition metal oxides, tunnel-type oxides, phosphates, fluorides, organic compounds, Prussian blue and its analogues, have been proposed as the cathode material for SIBs [2]. Among them, sodium manganese layered oxides NaxMnO2 emerge as the most promising ones as they generally have relatively high theoretical capacity, 2D diffusion space for sodium ions and can be easily synthesized. However, NaxMnO2 still suffer from the obstacles, i.e. the serious capacity fading and bad rate performance because of ‘Jahn-Teller effect’ of Mn3+, and the low energy density as a consequence of the low voltage plateau of Mn3+/Mn4+ redox couple. Substitution Mn with other transition metal elements can be an effective way to overcome these problems [3]. In this work, the double metal (Cu and Mg) substitution is applied to enhance the electrochemical performance of P2-type Na0.67MnO2. The idea is to combine the advantage of inactive Mg ions (enhancing the stability) and active Cu ions (high voltage plateau of Cu2+/Cu3+) to improve electrochemical performance of the material. Compare to the un-substituted and single substituted materials, the co-substituted materials exhibits superior electrochemical performance, it can deliver the initial discharge capacity of 85 mAh g-1 at 180 mA g-1 with capacity retention of 93% after 500 cycles. Besides, Neutron diffraction, X-ray Absorption Structure (XAS) Spectroscopy and In-situ XRD are combined to obtain its structure information. It is found that the co-substitution of Cu and Mg can effectively suppress the multiple phase transitions during electrochemical process, and the structural stability is largely enhanced. [1] M. D. Slater, D. Kim, E. Lee, C. S. Johnson, Advanced Functional Materials 2013, 23, 947. [2] H. Pan, Y.-S. Hu, L. Chen, Energy & Environmental Science 2013, 6, 2338. [3] J.-Y. Hwang, S.-T. Myung, Y.-K. Sun, Chemical Society Reviews 2017.

Pressure-jump induced rapid solidification of melt: a method of preparing amorphous materials

By using a self-designed pressure-jump apparatus, we investigated the melt solidification behavior in rapid compression process for several kinds of materials, such as elementary sulfur, polymer polyether-ether-ketone (PEEK) and poly-ethylene-terephthalate, alloy La68Al10Cu20Co2 and Nd60Cu20Ni10Al10. Experimental results clearly show that their melts could be solidified to be amorphous states through the rapid compression process. Bulk amorphous PEEK with 24 mm in diameter and 12 mm in height was prepared, which exceeds the size obtained by melt quenching method. The bulk amorphous sulfur thus obtained exhibited extraordinarily high thermal stability, and an abnormal exothermic transition to liquid sulfur was observed at around 396 K for the first time. Furthermore, it is suggested that the glass transition pressure and critical compression rate exist to form the amorphous phase. This approach of rapid compression is very attractive not only because it is a new technique of make bulk amorphous materials, but also because novel properties are expected in the amorphous materials solidified by the pressure-jump within milliseconds or microseconds.

Dependence of E-H transition in argon ICP discharges for treatment of organic molecules

ABSTRACT Plasma surface cleaning is an alternative process that aims at the fully removal of organic contaminants on several kinds of materials. Despite its advantages, there are still lacks on the comprehension of the complex relations between plasma-generated species and organic molecules during plasma cleaning. In the present work, a linear alkane (hexatriacontane - C36H74), used as a contaminant model, was exposed to an Argon radiofrequency (RF) inductively coupled plasma (ICP). The by-products from degradation were monitored by optical emission spectroscopy (OES) and residual gas analysis (RGA), to identify the influence of sample positioning on E and H discharge modes regions. The exposition to H-mode discharge resulted in more intense and profuse emissions of C-H and C2 systems. RGA results show similar byproducts from degradation in both modes; however, the intensity from treatment in H-mode is largely greater. It was also observed that plasma etching in H-mode is enough to melt the sample, while E-type discharge leaves the surface of the sample apparently unchanged.

A review on the machining of cast irons

Nowadays, the search for new materials is concerning to reduce the relative “efficiency/weight” ratio and its costs, in general, in the whole manufacturing chain, since the design until the final manufacturing stage. The efforts to achieve these requirements must fall in one of two options: (i) selecting “new” materials with similar strength of the “old,” but with low density or (ii) increasing the strength of the existing materials by adding alloying elements or by heat treatment. Choosing the best material for a given application depends on a few parameters such as mechanical loads, thermal environments, manufacturing costs, recycling, public acceptance, and workability. Among several kinds of materials are the cast irons, which almost always provide good machinability and low production cost. Under the scenario of the Industrial Revolution to date, cast iron received great emphasis on its development from the point of view of its properties and economic advantages. Currently, among the metallic materials, cast irons are the second most produced, after steels. They are an extremely important group of metal for the industry because, by introducing alloying elements and applying appropriate heat treatment, their use has become viable in some applications that were exclusively of steels. The several grades and groups available, on the other hand, brings another concern about their machinability. After production on the foundry, cast irons always are processed by machining, involving a large amount of money. With the goal of bringing relevant information on the machinability characteristics of cast irons, this review was produced. It covers the main output parameters in machining (forces and power consumption, cutting temperature, surface roughness, recommended cutting tools, tool wear, and corresponding use of computational modeling technique, by using the finite element method) finalizing with future trends. It is hoped to fill a gap in the literature for those involved with machinability of this important metal.

Surface enhancement of molecular ion yield in a 2.45-GHz electron–cyclotron resonance ion source**Project supported by the National Natural Science Foundation of China (Grant Nos. 11175009 and 11575013).

High current hydrogen molecular ion beam is obtained with a specially designed stainless steel liner permanent magnet 2.45-GHz electron–cyclotron resonance (ECR) ion source (PMECR II) at Peking University (PKU). To further understand the physics of the hydrogen generation process inside a plasma chamber, theoretical and experimental investigations on the liner material of the plasma chamber in different running conditions are carried out. Several kinds of materials, stainless steel (SS), tantalum (Ta), quartz, and aluminum (Al) are selected in our study. Experimental results show that stainless steel and tantalum are much better than others in generation. During the experiment, an increasing trend in fraction is observed with stainless steel liner after O2 discharge inside the ion source. Surface analyses show that the roughness change on the surface after O2 discharge may be responsible for this phenomenon. After these studies, the pure current of ions can reach 42.3 mA with a fraction of 52.9%. More details are presented in this paper.

Stress-wave propagation and damage formation associated with hypervelocity penetration into polycarbonate

Hypervelocity impact experiments have been performed on polycarbonate to observe the impact-induced damage process progressing inside polymer material. Impact experiments have been conducted by impacting a sphere made of several kinds of materials using a two-stage light-gas gun. The damage evolution and stress wave propagation associated with hypervelocity impact have been observed via shadowgraphy using an ultra-high-speed camera. Recoded images clearly demonstrate how damages form during the hypervelocity impact event. The obtained time evolution of penetration show that the behavior of stress wave propagation associated with impact vary according to the penetrating motion, and the impact velocity dependence of penetration length and shape change depending on the deformation and fracture behavior of impactor during penetrating process. From these results, it is indicated that not only the mechanical characteristics of impactor material but also the change of penetrating motion associated with the deformation and fragmentation of impactor are key factors for impact-damage formation.

Effect of Anti-dots on the Magnetic Susceptibility in a Superconducting Long Prism

The magnetic susceptibility of a long mesoscopic superconducting square prism containing one/two (dot) anti-dots is calculated in the framework of the Ginzburg–Landau theoretical model. This magnetic susceptibility shows jumps at each of the vortex transition fields. We studied the influence of the number, size and geometry of the anti-dots on the magnetic susceptibility in a superconducting sample. We found interesting physical behavior when several kinds of materials filled into the anti-dot are considered.

Dense Carbon Coated Electrode for Biosensing Application Made By Platingin Molten Salt Bath

1. Introduction Carbon electrodes are widely used for various electrochemical bio-sensing applications. This is due to the electrochemical stabilities and biological adaptabilities. Furthermore, from the viewpoints of business, it is considered that carbon is reasonable in price compared with precious metals such as platinum or gold and supposed stabilities of material supply. There are several kinds of materials and methods for carbon electrode fabrication. Glassy carbon and boron doped diamond are relatively difficult to be fabricated in desired stereo shapes. Thin carbon films made by sputtering or CVD (usually less than 1μm) are difficult to cover the substrate surface thoroughly and not so conductive when being deposited on insulating substrate. Carbon paste coating can make relatively thick carbon layer, but it is not dense enough to prevent from holes, pores and voids, which disturb precise measurements. Therefore, it is practically impossible to make electrodes with thick and dense carbon layer in complexed shape using the conventional methods. We found that the carbon electroplating method developed by I’MSEP 1) can solve the problems to form the dense and thick (>1μm) carbon on metal substrates. Carbon films are electrochemically deposited on metal substrates in molten salt bath. The deposited carbon films are sufficiently dense, thick and conductive to be used for the electrodes for bio-sensing applications. We describe on the characters and electrochemical performances of the dense carbon coated electrode plated in the molten salt bath. 2. Formation of dense carbon coated electrode by plating The reaction of the carbon plating in the molten salt bath is the electrochemical oxidation of carbide ions dissolved in bath on anode. C2 2- → 2C ＋ 2e- Various types of metal substrate can be used. We used SUS304 as the substrate because it is able to be precisely fabricated in many ways including wet etching combined with photo-resist. Carbon layer can be made on the SUS surface uniformly even on the back side, edge and recesses. The electrode used in this experiment was plated under the following conditions:The molten salt bath LiCl-KCl mixed, Temperature : 500°C Cathode : Carbon plate, Current density : 3.3 mA/cm2 3. Electrochemical measurements using the dense carbon coated electrodesFigure 1 shows the cyclic voltammetry curves for the electrodes; dense carbon coated by plating (C plating, 2μm) , SUS304 as the substrate (SUS base) and carbon paste coated on the substrate (C paste, 2μm). The curves shown were recorded after ten times sweeps from －0.9 to +1.4V vs.Ag/AgCl in 0.1M HCl at 25°C . This indicates that C plating electrode has very wide potential window, where the base current of C plating electrode is almost zero, in comparison with C paste electrode. The characters of SUS was hidden due to the perfect coverage. The anodic current of C paste electrode may be caused by the oxidation of organic components or contaminants of the paste. Furthermore, we investigated the possibility that C plating electrode can be used for bio-sensing application. Figure 2 shows the results of glucose concentration measurements. In this case, with the existence of oxygen (continuously bubbled) as the mediator, 100mg/L of glucose oxidase (GOX) dissolved in the solution (phosphate buffer pH 5.8) generated H2O2 when glucose is replenished. Any modification of C plating electrode was not made to show the original properties. The steady current at +0.9 V vs.Ag/AgCl, where H2O2 is detected, was measured depending on the glucose concentration in the solution. The linear relationship between glucose concentration and current values were obtained. It is supposed that dense carbon coated electrode made by plating is capable to apply to various electrochemical measurements of biomarkers because it has very wide potential window. Additionally, some modification or arrangement of measuring methods should enhance the selectivity and sensitivity. Reference1) Yasuhiko Ito ; ECS Transactions, 41 (46) 43-55 (2012) Figure 1