bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoelectrochemical Oxidation of Methane at TiO2 nanotubes Arrays
Authors: Kadosh Yanir , Korin Eli , Bettlehiem Armand 
Published: February 2020

Methane, the primary component in natural gas, has extensive utilities in the chemical industry and as an energy source. The depletion of petroleum reserves highly motivates the exploitation of natural gas as an important hydrocarbon feedstock with a small environmental footprint. However, this potential energy source is being wasted due to the lack of an efficient utilization process that will integrate natural gas in the existing energy infrastructure. Methane is mostly burned in order to use its heat for power generation. In order to utilize methane efficiently, it may be chemically converted for energy conversion. Unfortunately, methane’s molecular structure has neither a functional group, nor a polar distribution to facilitate chemical interactions, resulting in a low chemical reactivity. Its C-H bond has one of the highest bond energies among hydrocarbons (413kJ/mol).
An alternative approach to utilize this fuel more efficiently is by the use of fuel cell technology. This has been demonstrated for the electrochemical oxidation of methane in solid oxide fuel cells at high temperatures (650-1100℃).
The present research investigates the photoelectrochemical oxidation of methane at anodized Ti photoanodes. TiO2 semiconductor generates highly reactive holes upon illumination that can drive the oxidation reaction. In this type of activation, the exploitation of light energy may dramatically reduce the energy required for the oxidation reaction. TiO2 photoanodes with a nanotube arrays structure are prepared via anodization of Ti foils followed by annealing at 500℃. This structure, which was characterized by SEM, XRD and TEM, has an efficient exposure to light with high surface area for the photocatalytic reaction. When examined by linear sweep voltammetry, this photoanode exhibits an increase of ~15% in the saturation photocurrent density (~0.5mA/cm2 at +0.2V vs. Hg/HgO) in the presence of methane, as compared to that obtained in the presence of an inert gas (water oxidation).
Enhanced Photocatalytic Efficiency of Self-Organized TiO2 Nanotube Layers Due to Secondary Materials
Authors: Sopha Hanna , Krbal Milos , Ng Siowoon , Zazpe Raul , Prikryl Jan , Macak Jan M. 
Published: February 2020

The self-organized TiO2 nanotube layers have attracted considerable scientific and technological interest over the past 10 years motivated for their possible range of applications including photo-catalysis, solar cells, hydrogen generation and biomedical uses [1,2]. The synthesis of 1D TiO2 nanotube structure is carried out by a conventional electrochemical anodization of valve Ti metal sheet. The main drawback of TiO2 is its applicability in the UV light (wavelengths < 390 nm).
One of the major issues to extend the functional range of nanotubes is to coat homogenously tube interiors by a secondary material. It has been shown that additional ultrathin surface coating of TiO2 by secondary materials such as Al2O3 [3], ZnO [4] or MgO [5] annihilates electron traps at the TiO2 surface and thus increases the photogenerated concentration of charge carriers. Recently, it has been demonstrated that just a single cycle of Al2O3 [6] or ZnO [4] deposited by atomic layer deposition (ALD) efficiently improves charge transport properties of the heterostructure while gradual passivation appears with increasing ZnO thickness due to stronger band-bending [4].
The presentation will focus in on the coating of the nanotube arrays by various secondary materials using ALD. The deposited materials influence strongly photo-electrochemical properties of nanotube layers. Experimental details and some recent photocatalytic [7, 8] results will be presented and discussed.
References:
[1] J. M. Macak et al., Curr.
Opin. Solid State Mater.
Sci.,
2007, 1-2, 3.
[2] K. Lee et al., Chem. Rev., 2014, 114, 9385.
[3] R. Zazpe et al., Langmuir, 2017, 33, 3208.
[4] A. Ghobadi et al., Sci. Rep.,
2016, 6, 30587.
[5] H. Park, et al., J. Electroceram.,
2009, 23, 146.
[6] J-Y. Kim et al., Nanotechnology,
2014, 25, 504003.
[7] H. Sopha et al., Appl. Mater. Today,
2017, 9, 104.
[8] S. Ng et al., Adv. Mater. Interfaces
2017, 1701146.
Using Air Liquid Interface for studying Mechanical Deformation of Cells in Microfluidic Channels
Authors: Sen Prosenjit , Singh Kotesa Rahul , Ananthasuresh G. K. 
Published: February 2020

Biological cells are known to respond to changes in their environment by changing their mechanical response. For several diseases (e.g. diabetes, spherocytosis) changes in mechanical properties of cells have been corelated with the progression of the disease. Changes in cells mechanical properties has also been corelated with their development and age. With the advent of advanced microfluidic characterisation techniques, the mechanical response of a large number of cells can be measured at the single cell level. These studies help in investigating fundamental questions in cell biology. These analysers are called microfluidic cell transit analysers. In this work we introduce a novel cell-transit analyser where an air-liquid interface is used as a mechanical element to induce deformability in cells. This technique enables both static and dynamic deformability measurements in live cells ex vivo.
The devices were fabricated using PDMS microchannels bonded to glass substrates. The air-water interface is formed using manually controlled syringes. A syringe pump was used to flow the cell containing samples. In this work, stiffer air-water interface (surface tension 72 mN/m) to deform more compliant Red Blood Cells (effective 20 mN/m) in micro-channels. As the interface stiffnesses are of similar order, the air-water interface also deforms. In the static mode, measurement of the air-water interface deformation allows us to measure the Laplace pressure drop and hence estimate the stiffness of the Red Blood Cells. Using our technique, we estimated the stiffness of a single RBC was measured to be 18±2 mN/m which is in good agreement with previous reports.
In the dynamic mode the RBC containing buffer was flowed from one side and air pressure was applied at the two perpendicular channels to create stable air-liquid interfaces with desired constriction widths. This allows us to perform high throughput measurements (>100 cells/s) of deformability index (DI) and transit time for different air-liquid interface constriction widths. The adjustments in constriction width can be made in real time and can be tuned to widths as small as 2µm by controlling the air-pressure. The technique also eliminates the cell-substrate interactions due to the use of a virtual wall.
In order to validate the ability of the technique to differentiate cell population based on mechanical response, DI and transit time for cells passing through the air-water interface constriction were measured for healthy and 0.01% Glutaraldehyde (GA) treated RBCs. The DI of the GA-RBCs was found to be smaller than healthy RBCs thereby confirming the effectiveness of the technique in deformability cytometry. Further, the mechanical response of cells to different constriction widths was measured. We found that for differentiating Red Blood Cells of different stiffness using DI and transit time, constriction widths < 4µm are optimum.
3D Printable Soft Conductive Nanocomposites
Authors: Ahmed Kumkum , Kawakami Masaru , Khosla Ajit , Furukawa Hidemitsu 
Published: February 2020

3D printing is getting remarkable consideration in recent years in miscellaneous areas and being focused in many hi-tech future possibilities in engineering 1,2. 3D printable conductive polymer composites are gaining massive interest due to their impending application in the field of robotics, tactile, optical displays, microelectrochemical systems and in numerous other applications 3-5. Here in this work we prepared new types of 3D printable nanocomposites with tunable flexibility employing ionic liquid (IL) and micro-walled carbon nanotube (MWCNT) in polymer matrix. The developed soft nanocomposites demonstrated high conductivity and mechanical flexibility and diverse strain%. Thermal properties of the nanocomposites were studied by TGA and we found that thermal stability were very high for all nanocomposites regardless of the composition. Dynamic mechanical analysis (DMA) revealed information about their transition temperature for softening and by modifying MWCNT and polymeric content it is possible to tune this temperature according to desired requirements. The nanocomposites were printed by FDM 3D printer freely and on nonconductive printed base substrate according to the required shape. We also investigated their mechanical and conductive properties by tuning the composition of the constituents in the nanocomposites and discussed about the critical compositions and limitations for 3D printing techniques. These newly developed nanocomposites are expected to create pronounced impact in electromechanical fields to develop soft robotics, actuator and sensor devices.
References

Kalsoom, U., Nesterenko, P. N. & Paull, B. Recent developments in 3D printable composite materials. RSC Adv.
6, 60355–60371 (2016).

Gross, B. C., Erkal, J. L., Lockwood, S. Y., Chen, C., Spence, D. M. Evaluation of 3D Printing and Its Potential Impact on Biotechnology and the Chemical Sciences. (2014).

Wei, X., Li, D., Jiang, W., Gu, Z., Wang, X., Zang, Z., Sun, Z., 3D Printable Graphene Composite. Publ. Gr. 1–7 (2015). doi:10.1038/srep11181

Guo, S., Qiu, K., Meng, F., Park, S. H. & Mcalpine, M. C. 3D Printed Stretchable Tactile Sensors. Mater.
29, 1701218 (2017).

Muth, J. T., Vogt, D. M., Truby, R. L., Mengüç, Y.,Kolesky, D. B., Wood, R. J., Lewis, J. A., Embedded 3D Printing of Strain Sensors within Highly Stretchable Elastomers. Mater.
26, 6307–6312 (2014).

Figure 1
Platinum Thin Film TCD Designed for 3 Omega Sensing of Gas Mixtures
Authors: Lotfi Ardalan , Navaei Milad , Hesketh Peter J 
Published: February 2020

Over the last few decades, the world of sensors has been revolutionized by exploring the disciplines of nanotechnology and sophisticated Nano-fabrication process. As a result, gas sensors have become smaller and more robust in the terms of sensitivity and accuracy. Furthermore, these sensors are able to cover a broader range of gases and volatile compounds increasing detection capabilities, allowing detection down to single ppm. However, challenges still exist in detecting certain gases, specifically ammonia. The chemical-based gas sensors for ammonia are not reliable due to several factors such as slow recovery time, sensor base-line drifting, vulnerability to degradation and false alarm [1]. On the other hand, the physical-based ammonia sensing approach has the advantage of fast response time and long-term durability [2], while the thermal conductivity detector suffers a lack of high sensitivity and selectivity.
In an effort to address these challenges, this study is designed to improve the limit of detection of a micro wire thermal conductivity gas sensor that enables the system to detect 100 parts per million for ammonia. The differential 3-Omega measurement technique uses two sensors, one as sensing sensor and the other as a reference [3,4]. It is a harmonic excitation technique that needs a sinusoidal current can produce high thermal stresses that shorten the sensor life-time. To increase the reproducibility of sensor fabrication process, the micro wire TCD sensor material is replaced with platinum. In summary, the new design of micro wire TCD includes optimized shape to bear the high thermal stresses caused by continuous current needed by 3-omega technique and higher stability of the temperature coefficient of resistance with platinum film.
[1] Azad, A. M., Akbar, S. A., Mhaisalkar, S. G., Birkefeld, L. D., & Goto, K. S. (1992). Solid‐state gas sensors: A review. Journal of the Electrochemical Society, 139(12), 3690-3704.
[2] Mahdavifar, A., Navaei, M., Hesketh, P. J., Dimandja, J. D., Stetter, J. R., & McMurray, G. (2015). Implementation of a polysilicon micro electro-thermal detector in gas chromatography system with applications in portable environmental monitoring. ECS Journal of Solid State Science and Technology, 4(10), S3062-S3066.
[3] Lotfi, A., Mahdavifar, A., Struk, D., Stetter, J. R., Navaei, M., & Hesketh, P. (2017). Ultimate Sensitivity of Physical Sensor for Ammonia Gas Detection Exploiting Full Differential 3-Omega Technique. ECS Transactions, 80(10), 1571-1578
[4] Kommandur, S., Mahdavifar, A., Hesketh, P. J., & Yee, S. (2015). A microbridge heater for low power gas sensing based on the 3-Omega technique. Sensors and Actuators A: Physical, 233, 231-238.

Figure 1
Study of the Inhibiting Efficiency of an ABS Coating Doped with Lansoprazole on Mild Steel
Authors: Viveros Sandra , Uruchurtu Jorge , Menchaca Carmina , Hernández-Gallegos Miguel 
Published: February 2020

Organic inhibitors have had a great boom in the field of research in the last decade, since they have been reported to be good inhibitors of corrosion by having in their chemical composition atoms of nitrogen, sulfur or oxygen, allowing to be absorbed on the surface of the metal, and for having environmentally friendly characteristics. Polymeric coatings have always been good protectors of corrosion in multiple metals in different solutions. Likewise, this project seeks to help the environment with the recycling of this waste polymer being used in multiple areas, mostly in the automotive industry, generating tons of waste in its manufacturing process. On the other hand, the remains of the expired medicines generate thousands of kilograms of garbage, which later become fuel for cement factories, contaminating the environment in a different way.
The aim of this study is to evaluate the corrosion protection of a polymer coating doped with an organic inhibitor extracted from an expired drug on mild steel in alkaline and basic solutions. Electrochemical tests were carried out, such as Electrochemical Impedance Spectroscopy, Electrochemical Noise and Polarization Resistance, and it was characterized by FTIR, XRD, and AFM to confirm the union of both elements.
Electrochemical tests shown, that the system coating/inhibitor had good results in the basic solution, maintaining a constant resistance in the time that the test lasted (2000 hours). Likewise, in the alkaline solution, the system coating/inhibitor indicate an offspring in the resistance, obtaining an inferior behavior that the blank. The FTIR and XRD characterization indicate that in the dissolution, there are no chemical reactions that affect the properties or characteristics of each component. In AFM shows that, although there are some pores in the area, the coating is uniform in the entire surface.
Adhesion of Electrolessly Deposited Ni-P Film on Silicon Wafer Using Gold Nanoparticle Catalysts
Authors: Takasaka Yuichi , Sakamoto Susumu , Matsumoto Ayumu , Fukumuro Naoki , Yae Shinji 
Published: February 2020

Formation of adhesive metal films on silicon wafers is important for electrodes of various devices. Autocatalytic electroless deposition has several advantages, e.g. simplicity of process, uniformity of deposited films, and covering on complicated structures. However, adhesion of metal films formed on silicon substrates using conventional pretreatments is not sufficient for the practical applications. We reported that adhesive metal films can be directly formed on silicon substrates by preliminarily depositing gold nanoparticles as catalysts without any other treatments.1-3 When palladium nanoparticles are used as catalysts, heat-treatment is needed before and after plating to obtain adhesive films.4 We also reported that single crystalline gold nanoparticles are epitaxicially grown and gold-silicon alloy is formed at the gold-silicon interface, which improves the adhesion of films.3 In this study, we investigate the factors which affect the adhesion of metal films produced on silicon substrates by the present method.
The gold nanoparticles were deposited on p-Si (100) substrates by immersing in a 0.5 mM HAuCl4 solution containing 0.15 M HF at 278 K. The Ni-P films were formed on the silicon substrates using a solution containing 0.1 M NiSO4, 0.3 M NaPH2O2, 0.1 M (CH2COONa)2·6H2O, and 0.1 M C4H6O5 at 343 K. The solution pH was adjusted to 4.8 with NaOH. The adhesion of deposited films was examined by a tape test based on JIS H8504 corresponding to ISO 2819 after room temperature aging at atmospheric ambient.
Figure 1a shows the percentage of the area of the Ni-P films that remained on the silicon substrate after the tape test as a function of the film thickness. No peeling occurred for the films thinner than 0.8 µm immediately after the film deposition. As shown in Fig. 1b the starting film thickness of peering increased with aging time and reached the maximum after aging for 7 days. Since the starting film thickness of peering increased with the square root of aging time, we consider that the improvement in adhesion is due to the atomic diffusion of gold into silicon at room temperature. However, the starting film thickness of peering become constant after 7 days aging. This indicates that there are factors which affect the adhesion of metal films other than the formation of gold-silicon alloy.

Acknowledgement

This work was partly supported by JSPS KAKENHI Grant Number JP26289276.

References

S. Yae, M. Enomoto, H. Atsushiba, A. Hasegawa, N. Fukumuro, S. Sakamoto, and H. Matsuda., ECS Trans., 53(6), 99 (2013).

H. Atsushiba, Y. Orita, S. Sakamoto, N. Fukumuro, and S. Yae, ECS Trans., 61(10), 9 (2014).

N. Yamada, H. Atsushiba, S. Sakamoto, N. Fukumuro, and S. Yae, ECS Trans., 69(39), 59 (2015).

V. M. Dubin, J. Electrochem. Soc., 139, 1289 (1992).

Figure 1
Electrochemical Evidence of the Catalytic Activity of Meso-Tetraphenylporphyrin Diacid in the Proton Reduction in Benzonitrile
Authors: Castro-Cruz Hiram Manuel , Macias-Ruvalcaba Norma Angélica 
Published: February 2020

Our work shows the electrochemical behavior of meso-tetraphenylporphyrin diacid (H4TPP2+) in tetrabutylammonium perchlorate Bu4NClO4 0.1 M / benzonitrile. On a cathodic sweep and scan rates between 0.1 and 3.0 V/s, H4TPP2+ undergoes two closely spaced consecutive reversible one-electron transfers (Ic’/Ia’ and IIc’/IIa’; Figure 1), which can be assigned to formation of diprotonated porphyrin radical cation (H4TPP•+), and isophlorin H4TPP species, respectively1. In presence of an extra equivalent of HClO4, a new reduction peak, IIIc’, is seen, suggesting that isophlorin H4TPP is being protonated. It is believed that the protonation takes place at one of the meso-positions of the porphyn ring leading to phlorin cation (H4TPFH+). The phlorin cation is electroactive and can be either oxidized (peaks IVa’ and Va’) or reduced (IIIc’)2. As seen in Figure 1, the addition of extra equivalents of H+ to solutions of H4TPP2+ provokes an increase in the current and loss of reversibility of the two reduction processes, Ic’/Ia’ and IIc’/IIa’. This behavior was explained as due to the reaction between the free protons in the medium and the hydrogen atom of the meso-position of the H4TPFH+, in a reaction that produces molecular hydrogen and regenerates the porphyrin diacid.
Digital simulation of the experimental voltammograms of H4TPP2+ indicates that the H4TPP•+ and H4TPP species are stable on the cyclic voltammetry time scale. However, coulometry experiments at the potential of the second reduction process show that at longer time scale, the isophlorin H4TPP undergoes coupled chemical reactions. Voltammograms of the electrolyzed solution exhibit oxidation and reduction signals that are characteristics of H4TPFH+ species, also the presence of the bands at 460 nm and 773 nm in the UV-visible spectrum is consistent with the presence of H4TPFH+ species3,4. It is also demonstrated that the H4TPFH+ species can be reoxidized back to the original H4TPP2+ in a two-electron process.

References.

1. H. M. Castro-Cruz, thesis, UNAM (2017). http://132.248.9.195/ptd2017/junio/410088896/Index.html
2. Y. Cui, L. Zeng, Y. Fang, J. Zhu, C. H. Devillers, D. Lucas, N. Desvbois, C. P. Gros and K. M. Kadish, ChemElectroChem, 3, 228–241 (2016).
3. G. Peychal-Heiling and G. S. Wilson, Anal. Chem., 43, 550–556 (1971).
4. G. L. Closs and L. E. Closs, J. Am. Chem. Soc., 85, 818–819 (1963).

Figure 1
Polystyrene/Ceria Core/Shell Abrasive Based Slurry for Highly Enhanced Oxide-Film Polishing Rate and Scratch-Less in Chemical-Mechanical-Planarization
Authors: Jeong Gi Ppeum , Yun Sang su , Son Young hye , Yoon Seok Jin , Nam Hae won , Park Jin-Hyung , Park Jea-Gun 
Published: February 2020

The SiO2-film chemical-mechanical-polishing (CMP) is essential process for Shallow Trench Isolation (STI) and Inter Layer Dielectric (ILD) CMP. The key performance parameters are high polishing rate and scratch-less in SiO2-film CMP. In SiO2-film CMP, wet-ceria was widely used for scratch-less SiO2-film CMP. However, the wet-Ceria abrasive has crystalline sharp <100>, <100>, and <111> facet, which resulted in generating scratches on SiO2-film by stick and slip mechanism after SiO2 CMP, as shown in Fig.1. Thus the scratches induced by wet-ceria abrasives can be a major cause of poor device operation and yield drop in the memory device manufacturing. In our study, therefore, we designed a novel SiO2-film CMP slurry using the PS/ceria core/shell as an abrasive to enhance SiO2-film polishing rate and scratch-less after SiO2-film CMP.
PS/ceria core/shell particles were synthesized, which are relatively soft and round by using polystyrene and ceria particles. Figure 2(a) shows the synthesis mechanism of PS/ceria core/shell, illustrating that Ce4+ ion was added in the PS of negative charge to form Ce4+ seed on the surface and grow it during 7 h with 70 ℃. The TEM image of the synthesized PS/ceria core/shell was shown in Fig. 2(b). First, we investigated the polishing rate of SiO2-film using PS/ceria core/shell abrasives. The polishing rate of SiO2-film was 564 Å/min when using PS/ceria core/shell and 350 Å/min when using wet-ceria as abrasives, as shown in Fig.3. This result means that the real contact area of PS/ceria core/shell is larger than that of 70 nm size wet-ceria. Second, we measured the surface roughness [root-mean-square (RMS) at 10 x 10-um scanning area] of SiO2-film and the surface defect such as scratch after CMP. The surface roughness of SiO2-film was 0.327 nm using wet-ceria and 0.202 nm using PS/ceria core/shell, respectively, as shown in Fig. 4(a). The number of scratch was 51-ea in 10-mm2 area and the deepest depth of scratch was 18 nm using 70 nm size wet ceria. However, the number of scratch was 10-ea in 10-mm2 area and the deepest depth of scratch was 2.3 nm using PS/ceria core/shell, as shown in Fig. 4(b). These results indicate that the hardness of PS/ceria core/shell is smaller than that of 70 nm size wet-ceria. In our presentation, we will review the mechanism for improving CMP performance such as high polishing rate, low surface roughness and scratch-less after CMP when using the PS/ceria core/shell abrasive based slurry.
* This research was supported by the MOTIE(Ministry of Trade, Industry & Energy (10085643) and KSRC(Korea Semiconductor Research Consortium) support program for the development of the future semiconductor device. This work was financially supported by the Brain Korea 21 Plus Program in 2018 and Research & Business Development Program Announcement funded by the MOTIE (N0002026).

Figure 1