bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) New Cyclic Porphyrin Arrays ~ Preparation and Specific Elution Behavior on Modified Silica-Gel Columns
Authors: Satake Akiharu 
Published: February 2020

Functionalized nanorings are expected to provide unique reaction fields in which specific and selective molecular transformation occurs. Here, we designed new cyclic porphyrin trimers (CP3s) in which three porphyrin moieties were connected through 2,2’-bipyridyl groups at their 3,3’-positions. CP3s were synthesized by nickel-mediated reductive coupling reaction of bis(2-chloro-4-methoxycarbonyl-6-pyridyl)porphyrinatozinc derivatives (1).(ref. 1) In a CP3, three bipyridyl parts are directed toward the center of the ring. Unlike metal-organized porphyrin cages formed from tetrapyridyl substituted porphyrins and metal ions, the three bisnitrogen pairs on the three bipyridyl moieties in CP3 are not used to construct the macrocyclic structures. Therefore, active metal species, such as coordinatively unsaturated complexes can be generated inside the rings, whereas generation of such active species in metal-oraganized nanocages is generally difficult because of destabilization of the skeletons. As well as the three bidentate 2,2’-bipyridyl ligands, three tetradentate porphyrinato parts gives metal ligands. The two kinds of metal ligands connected in a circular manner to provide a macrocyclic ligand for multicofacial and multinuclear complexes within a one-nanometer cavity. In fact, three π-allyl palladium complexes were incorporated into a zincporphyrin nanoring to give a hexametallic complex.
During the synthesis of CP3s, an efficient separation method by using modified silica-gel columns was discovered. Reductive coupling of bis(chloropyridyl)porphyrin 1 gave mixtures of acyclic and cyclic porphyrin oligomers. They were eluted in the order of hydrodynamic volume of the oligomers on gel permeation chromatography (GPC), and repeated GPC processes were necessary to obtain pure material of CP3. To reduce the time- and solvent-consuming processes, several modified silica-gel columns, COSMOSIL series supplied from Nacalai Tesque, PYE (pyrene-modified), π-NAP (naphtalene-modified), PBB (pentabromobenzene-modified), NBE (nitrobenzene-modified), and CN-MS (cyanopropyl), were tested. When a mixture of pyridine and toluene was used as an eluent, extremely specific retention behavior of CP3 was observed on the modified silica-gel columns. Under the conditions, other acyclic oligomers were eluted without retention. Therefore, the target CP3s can be much easily isolated from reaction mixtures compared with GPC separation. The observed specificity is probably related to molecular recognition between CP3s and substituents on the used modified silica-gel columns.

Reference

1) Ohkoda, Y., Asaishi, A., Namiki, T., Hashimoto, T., Yamada, M., Shirai, K., Katagami, Y., Sugaya, T., Tadokoro, M. and Satake, A., Chem. Eur. J., 2015, 21, 11745–11756. doi:10.1002/chem.201501854.
Renewable Carbon Sources and Novel Technologies for the Manufacturing of Carbide Parts
Authors: Martinez-Duarte Rodrigo 
Published: February 2020

Carbides are a class of high performance materials used in a variety of applications ranging from cutting tools to rocket nozzles. Examples of common carbides include Tungsten, Titanium and Boron Carbides. The synthesis of carbide is based on the reaction between carbon and metal or metal oxide powders at high temperatures. Current technology heavily relies on the use of carbon powders from the petrochemical industry. The reactant powders, or the already reacted carbide powder, are then pressed into specific shapes. Here, I will briefly detail current research on the use of renewable resources as the carbon source and on novel technologies to shape precursors to carbide parts.
The premise regarding the use of renewable resources is that a biopolymer-metal oxide nanoparticle composite can act as a carbide precursor. The biopolymer carbonizes below 1000 C leading to a carbon matrix decorated with metal nanoparticles. As the temperature is increased, these react to yield carbide. In my group we are exploring common biopolymers such as carrageenan, an extract from seaweed; chitin, from shrimp shells; konjac gum from the plant with the same name. We also actively exploring cellulose, from plants and bacteria, in the shape of powder, paper or individual fibers. The environmental cost of extracting these biopolymers is expected to be far less than petroleum-based ones while the colloidal proximity between the polymer and the metal nanopowders is expected to allow for the use of lower temperatures to complete the carbide-forming reaction. Thus, the process can be more energetically efficient than current ones.
Regarding manufacturing of precursor shapes, we are actively studying 1) the extrusion of composite pastes towards additive manufacturing of carbide precursors; 2) an origami-inspired technology by using cellulosic paper as the carbon source; and 3) a nanomanufacturing platform featuring the physical manipulation of bacterial cells capable of extruding cellulose nanofibers under optimized culture conditions.
In-Vivo Characterization of Glassy Carbon µ-Electrodes and Histological Analysis of Brain Tissue after Chronic Implants
Authors: Vomero Maria , Dryg Ian , Maxfield Tyler , Shain William , Perlmutter Steve , Kassegne Sam 
Published: February 2020

For neural applications, materials that combine excellent electromechanical properties with long-term (> 5 years) and high fidelity performance capabilities have not yet been reported. Good electrodes should not only be able to adapt to eventual physiological changes in the body (e.g. inflammatory responses), but also able to perform without damaging the host tissue. The combination of these two characteristics is difficult to accomplish, because the ability of a material to undergo changes is often accompanied by the formation of reaction products that might interact with the surrounding tissue, and eventually harm it. Glassy carbon is a biocompatible and electrochemically inert material with tunable mechanical and electrical properties, high charge injection capacity and great resistance to corrosion. These merits motivate the use of glassy carbon for neural applications, and in particular for the realization of electrocorticography (ECoG) microelectrodes that can sense and stimulate brain activity. Thus we propose to replace the commonly used noble metals like platinum, gold and iridium, with glassy carbon to improve the performances of traditional neural prostheses, thanks to better charge transfer capabilities and higher electrochemical stability. This investigation specifically reports characterization of glassy carbon microelectrode arrays (MEAs) used to sense and stimulate neural activity. Further, we report on key findings in long-term effects based on histological analysis of the brain tissue after chronic implants. Significant focus is given in this work to the investigation of tissue responses of motor cortex after 6 weeks of implantation, and to materials degradation of chronic in-vivo implants. In-vivo long-term impedance measurements and brain activity recordings are also performed to test the functionality of the neural devices and reported here.
Effects of a Magnetic Field on Anodic Dissolution and Surface Morphology of Iron in a Chloride Solution with Nitrite Ions
Authors: Chen Zhen , Li Hongjuan , Xiao Qian , Lu Zhanpeng 
Published: February 2020

The corrosion of metallic materials in industrial and natural environments,especially localized corrosions such as pitting corrosion, crevice corrosion and stress corrosion cracking, caused huge damage. Some metallic components servicing in corrosive environments can be affected by magnetic fields produced by the special electrical equipment nearby. To analyze and evaluate the corrosion behavior under magnetic field, it is necessary to understand the effect of magnetic field on uniform and localized corrosion.
In this study, the effects of a 0.4T magnetic field on the electrochemical behavior and corrosion morphologies of iron in chloride solutions with sodium nitrite ions were studied by optical microscope (OM), scanning electron microscope (SEM) and several electrochemical methods such as potentiodynamic polarization curve, potentiostatic polarization and electrochemical impedance spectroscopy,
Potentials in different regions of the anodic polarization curves were chosen to for potentiostatic polarization by applying or removing a 0.4T magnetic field. The current density vs. time curves were measured, as shown in Fig. 1. The impact of magnetic field on the surface morphology of the electrodes after potentiostatic polarization were observed.
The anodic current density increased with increasing polarization potential with or without a 0.4T magnetic field. The current density was very low in the passivation regions during potentiostatic polarization, which was reduced by the applied magnetic field, as shown in Fig. 1 a. The effect of the applied magnetic field on the the current density in near the passivation-transpassive transition potential was complex. The applied magnetic field increased the anodic current density under high potentials such as 0.4 V(SCE), as shown in Fig. 1 b.
The changing of pit number and area for iron in chloride solutions with sodium nitrite with polarization potential exhibited differences with or without 0.4 T magnetic field. The impact of magnetic field on the pitting corrosion is closely related to the polarization potentials, polarization time and the initial state of the electrode surface.

Figure 1
The Effects of Hydrogen on Corrosion Products Formed on Iron in Chloride Solutions
Authors: Ejaz Ahsan , Chen Junjie , Xiao Qian , Han Guangdong , Lu Zhanpeng 
Published: February 2020

The effects of charged hydrogen on the properties of the surface films formed on iron in pure water and 10-4 to 0.5 mol/L NaCl solutions at 25°Cwere investigated by open circuit potential (OCP) measurements, optical microscope, scanning electron microscope and X-ray diffraction (XRD). After 21h immersion in pure water, the surface of non-charged iron did not significantly and showed only local corrosion sites, while the surface of hydrogen-charged iron was covered with dark film with many yellow corrosion sites on it. After 21h immersion in 10-4 mol/L NaCl solution, the non-charged iron was partly covered by surface film, while the hydrogen-charged iron was fully covered by surface film, as shown in Fig. 1. After 21h immersion in 0.5 mol/L NaCl solution, the surface of the non-charged iron was partly dark and partly covered with yellow rusts, and the surface of the hydrogen-charged iron had a larger area covered with more yellow rusts than that on the non-charged iron, as shown in Fig. 2. Results of OCP monitoring showed that OCP values for hydrogen-charged iron in pure water, 10-3 and 10-4 mol/L NaCl solutions were lower than those for non-charged iron, as partly shown in Fig. 3a. In 0.5 mol/L NaCl solution, the OCP differences between non-charged iron and hydrogen-charged iron was at first big but gradually became smaller with increasing immersion time, as shown in Fig. 3b. Raman spectra showed the presence of magnetite in the film on hydrogen-charged iron after immersion in 10-4 mol/L NaCl solution, as shown in Fig. 4a, which was supported by XRD results. Yellow rust and the XRD peak for hematite in the films on non-charged and hydrogen iron specimens (Fig. 4) indicated that the mechanism for the effect of hydrogen on the corrosion products of iron in dilute NaCl solutions could be different from that in concentrated NaCl solutions. In solutions with a high chloride concentration, hydrogen in iron might be able to promote the formation of high valence iron oxide, while in many other cases it was found that the formation of magnetite was promoted by hydrogen in iron.

Figure 1
Inhibition Effect of Some Cationic Surfactants on Carbon Steel in 1M H2so4 and 1M HCl Medium
Authors: Branzoi Florina , Pacuretu Catalina , Branzoi Roxana 
Published: February 2020

The inhibition effect of some cationic surfactants (bromide hexadecylpyridiunium, bromide haxadecyltrimethylammnonium and chloride dodecyltrimethylammonium) on the corrosion of two carbon steels (OL 37 and OLC 45) in 1M H2SO4 and 1M HCl was studied weight loss method, potentiostatic and potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and metallurgical microscopy techniques.
The inhibition activity analysis of these organic inhibitors was made by assuming that the mechanism of inhibition by organic molecules is chemisorptions. We presume that, these organic inhibitors inhibit corrosion of carbon steel by a protective mechanism, forming insoluble iron complexes and repairing the porous oxide layers. The addition of the organic inhibitors led in all the cases to inhibition of the corrosion process in acidic solution at different temperatures. At concentrations lower than critical micelle concentration (CMC), the inhibition of these three surfactants is negligible and at concentrations higher than the CMC, the inhibiting action of these inhibitors increases rapidly. Polarization curves indicate that they are mixed type of inhibitors. The inhibition efficiency was high in all the studied cases. The corrosion parameters obtained from polarization curves and from EIS spectra are in good concordance and point out the inhibitory action of cationic surfactants. The adsorptions of the organic compounds on the carbon steels surface obeyed Langmuir’s isotherm. The thermodynamic parameters of adsorption enthalpy (ΔH0), adsorption free energy (ΔG0) and adsorption entropy (ΔS0) were calculated. Further characterization using Fourier transform infrared spectroscopy (FT-IR) demonstrates the adsorption of organic inhibitors and the formation of corrosion products on the carbon steels surface. The inhibition process was attributed to the formation of the adsorbed film on the metal surface that protects the metal against corrosive agents. The EIS measurements have confirmed this protection and pointed out the formation of adsorption layers on the electrode surface.
Comparative Corrosion Behavior of Austenitic Stainless Steels in Carbonate Melt at 650 °C Under Controlled CO2-O2 Environment
Authors: Sah Santosh Prasad , Tada Eiji , Nishikata Atsushi 
Published: February 2020

Concentrated solar power (CSP) has recently attracted much attention as clean energy mainly for base load applications. High temperature CSP technology has high efficiency and it can attract wide commercial applications. Corrosion of metallic materials is a key problem for high temperature CSP systems. Careful selection of molten medium and metallic material can slow down the corrosion processes and hence extend the overall life span of CSP plants. High temperature oils and nitrate-based salts are commonly used for commercial CSP plants. These materials are not stable at temperature higher than 600 °C. However, alkali metal carbonates are stable beyond 800 °C and have working temperature of ~ 400-800 °C. These carbonates are less expensive and more environment friendly than the state-of-art high temperature oils [1]. Employing high corrosion resistance of cheaper alloys, like stainless steels, could significantly promote the popularity of CSP plants. In this study, corrosion behavior of austenitic stainless steels (SS) is observed in ternary alkali carbonate melt at 650 °C under defined CO2-O2 gas environment.
Weight loss, electrochemical characterization and morphological and microstructural examination were carried out to understand the corrosion behavior of Type 304 SS, Type 316L SS and Type 310S SS in 43Li2CO3-31.5Na2CO3-25K2CO3 (mol%) melt at 650 °C under flowing 0.98 atm CO2-0.02 atm O2 mixed gas.
Weight loss observed due to 24 hours corrosion is 7.7 mg cm-2 for Type 304 SS, 6.5 mg cm-2 for Type 316L SS and 1 mg cm-2 for Type 310S SS. Potentiodynamic polarization showed that corrosion of SS is a cathodic-controlled process. Corrosion potential of Type 310S SS is nobler than that of Type 316L and Type 304 SS. Reduced weight loss of Type 310S SS due to corrosion should be due to high potential of anode reaction. Cathodic limiting current is not significantly different for all the SS; however, it is slightly higher for Type 304 SS than that of Type 316L and should be responsible for slightly higher weight loss of Type 304 SS. Anodic polarization behavior well agrees with the weight loss observed for all the examined SS. SEM and EDS analysis showed that a very thin Cr-rich uniform corrosion layer is formed on Type 310S; however, thicker corrosion layer formed on Type 304 is composed of a heterogeneous mixture of Cr- and Fe-rich phases. Corrosion layer formed on Type 316L is Cr-rich but locally contains Fe-rich phases. Corrosion resistance of SS in carbonate melt in decreasing order is as: Type 310S>Type 316L>Type 304.
This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “energy carrier” (Funding agency: JST).

Reference

K. Vignarooban, X. Xu, A. Arvay, K. Hsu, A. M. Kannan, Applied Energy, 146 (2015) 383-396
Polarization Behavior of Iron Under Artificial Zinc Corrosion Products Formed from Aqueous MgCl2 Solutions Containing Zn2+
Authors: Tada Eiji , Nishikata Atsushi 
Published: February 2020

Galvanized steels are widely used in various industrial fields such as automobiles and construction since they have excellent corrosion protection in atmospheric corrosion environments. The corrosion protection property of Zn coating has been improved by addition of another elements such as Mg and Al. However, the effect of Mg on corrosion protection of the galvanized coating is still unclear. In this study, we investigated polarization behavior of iron under artificial zinc corrosion products formed in an aqueous solution containing Mg2+.
A pure iron bar (purity: 99.9%) was annealed at 850 oC for 2 h and sliced into disks of 12 mm in diameter and several millimeter in thickness. The surface of the iron disk was abraded with SiC papers up to JIS #2000 grit and then the disk was etched chemically to get a mirror-like surface finish. To form artificial zinc corrosion products on an iron disk, it was polarized cathodically at various potential for 1.8 ks in an aqueous solution of 1 M MgCl2 containing ZnCl2. The zinc corrosion products formed on the iron disk was investigated by SEM and other analytical instruments. Polarization behavior of iron covered with the artificial zinc corrosion products was investigated by the measurements of cathodic and anodic polarization curves in 0.1 M NaCl.
Artificial zinc corrosion products were successfully formed on an iron disk during cathodic polarization in 1 M MgCl2 containing ZnCl2. It was found from surface analysis that the amount of the artificial zinc corrosion products formed on the disk changes depending on polarization potential. At around -0.85 V (SSE), the whole surface of the iron disk was covered homogeneously with zinc corrosion products. Cathodic polarization curves for iron covered with artificial zinc corrosion products showed that oxygen reduction reaction (ORR) is slightly inhibited in comparison with ORR on bare iron. On the other hand, anodic polarization curves for iron covered with artificial zinc corrosion products showed that anodic dissolution of iron under the zinc corrosion products also tends to be suppressed. The effect of Mg on polarization behavior of iron covered with artificial zinc corrosion products is going to be discussed in detail.
(Invited) Tuning the Strain and Physical Properties of Highly Epitaxial Perovskite Thin Films on Vicinal Substrates
Authors: Lin Yuan , Yao Guang , Gao Min , Chen Chonglin 
Published: February 2020

Controllable interfacial strain can manipulate the physical properties of epitaxial films and help understand the physical nature of the correlation between the properties and the atomic microstructures. In this presentation, we demonstrated that the interface strain in epitaxial thin films can be well controlled by adjusting the miscutting angle of a vicinal single-crystal substrate via a surface-step-terrace matching growth mode. Epitaxial perovskite or perovskite-like oxide thin films such as CaCu3Ti4O12 (CCTO) and (Ba,Sr)TiO3 were grown on vicinal (001) single-crystal LaAlO3 (LAO) substrates with various miscutting angles of 1.0°, 2.5°, and 5.0° by a polymer assisted deposition (PAD) technique. High-resolution X-ray diffraction were employed to study the epitaxial nature and interface strains induced by the substrate step terrace dimensions. It is found that the strain is determined by the mismatch between the lattice of the thin film and the substrate step terrace dimensions. A model is proposed that both compressive and tensile strained domains would form in the film to fit the size of each step terrace whereas the ratio of the two kinds of domains can be tuned by the miscutting angle. Based on this growth mode, a proper design of the substrate step terrace dimension can tune the properties of the thin films. For example, an optimized design of a CCTO thin film on a 5o-miscutting (001) LaAlO3 substrate can maintain a similar dielectric constant and reduce the dielectric loss by half an order of magnitude compared with the films grown on the regular (001) LaAlO3 substrates, briefly by releasing a large part of the interfacial stress through the complementary strained domains instead of dislocations.
This work is supported by the National Basic Research Program of China (973 Program) under Grant No. 2015CB351905, the National Natural Science Foundation of China (Nos. 51172036, 11329402, and 51372034), and the Technology Innovative Research Team of Sichuan Province of China (No.2015TD0005).
Low Dielectric Constant, Air-Cavities Created By the Use of Low-Ceiling Temperature Polymers
Authors: Schwartz Jared , Phillips Oluwadamilola , Pan Zhaoqun , Sutlief Alexandra , Kohl Paul A 
Published: February 2020

Low decomposition temperature (<200oC) template polymers that decompose into gaseous products have been used as templating materials in the formation of air-cavities and porous dielectrics. It is especially important for the sacrificial, templating polymer to decompose cleanly to gaseous products at a specific temperature, which is compatible with the other materials present, especially the dielectric superstructure surrounding the sacrificial material. It is also important for the sacrificial polymer to leave little or no residue so that undesirable materials are not formed during the process. One method of producing a low-temperature sacrificial material is the use of a low ceiling temperature polymer. Above the ceiling temperature, the polymer reverts back to monomers. A polymer with a low ceiling temperature can rapidly depolymerization back to monomer and vaporize, if the monomer vapor pressure is suitably high at room temperature (>10 Torr). This work focuses on the synthesis and decomposition of low ceiling temperature polyaldehydes using high vapor pressure monomers. Polyphthalaldehyde could be used as the template polymer for creating air-gaps and porous dielectrics. Polyphthalaldehyde has a moderate decomposition temperature of 125oC and a moderate vapor pressure. Copolymers of aldehydes are of interest because the vapor pressure of the sacrificial polymer decomposition products can be increased. Polyaldehyde copolymers were synthesized with the goal of increasing the thermal decomposition temperature and increase the evaporation rate of the decomposition products. A random copolymer of phthalaldehyde and butyraldehyde raised the 50 percent decomposition temperature of the polyaldehyde by 25oC when compared to the phthalaldehyde. homopolymer. Even a small amount of the higher vapor pressure monomer, butyraldehyde, increased the evaporation rate substantially.