bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maskless Macrosale Generation of Periodic 3D Semiconductor Nanostructures in Response to Defined Illumination Inputs
Authors: Carim Azhar I , Batara Nicolas A. , Premkumar Anjali , Atwater Harry A , Lewis Nathan S 
Published: February 2020

Template-free photoelectrodeposition of semiconducting chalcogen alloys resulted in the spontaneous generation of highly periodic nanostructured films over macroscopic length scales. The exact nature of the optical excitation was encoded in the deposit morphology in terms of the feature sizes, periodicities, anisotropies, and orientations of the nanoscale pattern. The use of unpolarized light generated isotropic morphologies consisting of ordered arrays of nanopores whereas linearly polarized light resulted in a highly-anisotropic lamellar morphologies with the long axes of the patterns aligned along the E-field vector. Utilization of two same-wavelength, non-orthogonally polarized sources simultaneously generated patterns oriented along the average E-field vector and with degrees of anisotropy related to the difference in orientation between the two input E-field vectors and the phase correlation between the sources. The illumination spectral profile encoded the pattern periodicity and feature width. A single periodicity in a single in-plane direction was consistently observed even with the use of broadband and multimodal spectral profiles and this periodicity was found to be sensitive to all investigated tuning of such profiles. The incidence of the illumination set the direction the material grew from the substrate, mimicking natural phototropism: grazing illumination resulted in growth at significant angle to the surface normal. Modeling of the growth using a combination of full-wave electromagnetic simulations of light absorption and scattering coupled with Monte Carlo simulations of mass addition accurately reproduced the experimentally observed morphologies and indicated that the encoding process was a consequence of the fundamental light-matter interactions during growth.
This photoelectrochemical deposition process is unique from other methods of generating ordered mesostructures with electrochemical means as no photomask, no photoactive substrate, no lithographic processing, nor any chemical templating agents (ligands, surfactants) were utilized. Illumination was simply conformal over the entire substrate surface (no far-field spatial modulation was used nor required). Complete nanoscale patterning over cm2 areas required only several minutes. Moreover, films were deposited from aqueous solution using oxide precursors at room temperature with low-intensity illumination (~10 mW cm-2). Thus, this process displays significant potential to possibly enable the generation of complex morphologies for functional materials without several limitations imposed by traditional fabrication techniques.
DFT Study of Surface and Interface Issues in High-Voltage Cathodes for Li-Ion Batteries
Authors: Soto Fernando Antonio , Sharifi-Asl Soroosh , Shahbazian-Yassar Reza , Balbuena Perla B 
Published: February 2020

The development of stable materials for cathodes in lithium-ion batteries (LiBs) is a major bottleneck for the commercialization of high-energy density rechargeable batteries. Lithium cobalt oxide (LiCoO2) is one of the most heavily used cathodes for LiBs. LiCoO2 exhibits fair electrical conductivity and Li+ mobility with an operational voltage of 4 eV. Moreover, the theoretical capacity of LiCoO2 is 274 mAh/g corresponding to a full Li+ extraction, producing CoO2. However, its practical capacity is only 130–150 mAh/g, indicating that only half of the Li atoms can be used during the “rocking-chair” de/intercalation process. Moreover, because of safety concerns (e.g. thermal stability and interaction with organic electrolytes with high volatility and flammability) its usage in high power and high energy density batteries is abandoned. Indeed, at high temperatures or high cut-off voltages, LiCoO2 decomposes and desorbs oxygen. The evolved oxygen reacts exothermically with the flammable electrolyte. This oxygen evolution jeopardizes the safety of the cell due to the magnitude of this highly exothermic reaction.
In our previous work, we found that the (104) and (012) surfaces are more prone to O2 release. Ab-initio molecular dynamics (AIMD) results show that the under-coordinated oxygen atoms from the delithiated structures can combine and eventually evolve as O2. Thus, the intrinsic surface properties of cathodes and the interfacial interactions between cathode and electrolyte need to be considered to enhance the cathode stability. The surface engineering and design of the electrode material have been proposed as a promising path to achieving safe and high-voltage cathodes for LiBs. In this work, firstly we report the stability, interfacial chemistry, oxidation-reduction behavior and surface thermodynamics of the major surfaces of LiCoO2 based on the calculations obtained with the density functional theory (DFT) approach. Further, we present the results achieved from DFT-based calculations and experimental techniques (e.g. electrochemical cycling, in-situ heating transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Raman characterizations) on the surface coating approach to enhance the structural stability of LiCoO2 by providing a physical barrier for oxygen evolution. Our experimental work shows that the coated sample could exhibit more than 75% capacity retention after 40 cycles while the pristine sample failed after 20 cycles with the same condition. Our computations suggest that the interaction between the physical barrier and the electrode’s surface leads to an interfacial chemical bonding that prevents O2 evolution. Overall, we expect that this combined approach will allow improving the overall performance of the battery by addressing the multifaceted problems that play a role in the safety problems of cathodes.
Patchable Ion Channel Pressure Sensors Inspired By Somatic Organs
Authors: Chun Kyoung-Yong , Son Young Jun , Han Chang-Soo 
Published: February 2020

Among vital elements in our body, ion channel are essential units which sustain life in all living cells as continuously transporting appropriate ions through plasma cell membranes. In addition, the somatic functions of ion channels are fundamentally indispensable for sensory organ homeostasis. For decades, biological ion channels have led to much inspiration because of their unique and exquisite operational functions in living cells. Specifically, their extreme and dynamic sensing abilities can be realized by the combination of receptors and pores coupled together to build ion channel systems.
In this presentation, we demonstrate that artificial ion channel pressure sensors inspired by nature for detecting pressure are highly sensitive and wearable. Our ion channel pressure sensors basically consisted of receptors and nanopore membranes, enabling dynamic current responses to external forces for multiple applications. The ion channel pressure sensors had a sensitivity of ∼5.6 kPa−1 and a response time of ∼12 ms at a frequency of 1 Hz. The power consumption was recorded as less than a few μW. Moreover, linear regression was performed in terms of temperature, which showed no significant variations, and there were no significant current variations with humidity. The patchable ion channel pressure sensors were then used to detect blood pressure in humans, and different signals were clearly observed for each person. Additionally, modified ion channel pressure sensors detected complex motions including pressing and folding in a high-pressure range.
In comparison to previous pressure sensors, our ion channel pressure sensors engaged sensory organs could provide feasible control of the bandwidth via selecting different electrolytes and unique signal shape according to the type of pressure receptor chosen, and the dynamic output signal may offer discrete information for an object. We expect that if the diverse functions of ion channels in nature could be further modified or mimicked for various applications, then artificial sensory systems such as the one described in this study would be tremendously greeted in a new era of sensors.
A Wearable Gas Sensor of GO and TiO2 Composite with High Selectivity
Authors: Lee Eunji , Chung Yoonsung , Lee Doohee , Yoon Jaesik , Lincoln Christopher , Prorok Bart Charles , Woo Sungpil , Yoon Youngsoo , Kim Dong-Joo 
Published: February 2020

With aging population and prevalence of chronic diseases, daily healthcare system became an important interest for many people. There has been much research to combine medical knowledge and engineering technology for easy access of self-health management, and wearable respiratory monitoring system which is the result of sensing and wearable technological integration is considered as a cornerstone in daily healthcare system. Since early detection essentially equals to more chances of treatment that ultimately result in improvement of patient outcomes, the device for continuous respiratory monitoring could be life-saving system. Wearable gas sensor is anticipated as a promising daily healthcare device to play an important role of physiological monitoring by checking human’s breath. For wearable gas sensors, sensor should be weaved into clothing or accessories in which functional materials that distinguish amounts of gases also should be coated.
Many recent studies have discussed to improve the gas response of resistive metal oxide gas sensor (MOGS). However, selectivity is one important parameter for the implementation of MOGS. Little efforts to investigate selective gas sensing were made in graphene based sensor. In MOGS, incorporating two materials such as zinc oxide and tin dioxide is known as a heterostructure. As two Fermi levels equilibrate to the same energy, charge carrier was transferred from one another, resulting in increasing sensor performance. As a similar approach, graphene oxide nanocomposite would enhance selectivity.
In this study, graphene oxide (GO) was constructed into the fabrics by simple solution method after sputtering interdigitated electrode, and ammonia gas sensing was conducted at room temperature. After that, we newly explored to use heterostructure of GO and TiO2 composite in order to improve selectivity which is the ability to discriminates the response of target gas from other interferents. The use of photon source enabled ethanol and methanol gas sensing at room temperature as the electrons stored in TiO2 reduced GO, which the color of solution was clearly changed. The morphologies of GO+TiO2 nanocomposite film on fabrics were analyzed with SEM and XRD, and comprehensive mechanism on GO’s ammonia, ethanol and methanol gas sensing will be drowned in detail.
This research was partially supported by the KIET Evaluation and Planning (20158520000210) grant funded by the Korea Government Ministry of Trade, Industry and Energy, and Agency for Defense Development (ADD) as global cooperative research for high performance and light weight bio-urine based fuel cell (UD160050BD).
An LED-Based Portable Multi-Excitation Fluorometer
Authors: Shin Young-Ho , Choi Jin-Woo 
Published: February 2020

Fluorophore microbeads are widely used in biomolecule detection/quantification, flow tracing reference for gases and liquids, pathogen detection, and other life science applications [1, 2]. Often multiple fluorophores need to be simultaneously detected using spectral multiplexing detection system which is typically operated at a single excitation wavelength with multiple fluorescent emission filters or vice versa [3]. However, it significantly limits the use of different fluorophores since they have different absorption and emission peak wavelengths. Here, we propose a portable multi-excitation fluorometer combined with 12 different bandpass emission filters that can a viable option for detecting multiple fluorophores. Six fluorophore microbeads were selected as target subject for this study: Nile blue, FITC, Cy3, Cy5, Quinine, and Rhodamine B.
The sensing system has six excitation light sources for stimulating different fluorophore microbeads in a solution. Each fluorophore bead has different peak absorption and excitation spectra enabling particle differentiation by measuring fluorescent responses under different excitation lights. A PDMS microfluidic chip technology was used to load an aliquot volume of the sample. A highly sensitive silicon photomultiplier tube (SiPM), MicroFC (SensL Inc., Cork, Ireland), was used to detect corresponding fluorescence signals from each fluorophore microbead. A filter wheel containing 12 different bandpass filters controlled by microprocessor was deployed above SiPM to selectively measure corresponding fluorescent signals, as illustrated in the figure.
In summary, we have developed an LED-based portable fluorescent sensing system that is capable of differentiating multiple fluorophore microbeads. Future work includes full characterization of the sensor system and fabrication of integrated electronic circuitry for a standalone and field-deployable fluorometer.
References
[1] Dai, C. et al. American Journal of Infection Control43, (2015), 78-81.
[2] Wu, S., Duan, N., Shi, Z., Fang, C. and Wang, Z. Analytical chemistry86, (2014), 3100-3107.
[3] Wan, Y., Sun, Y., Qi, P., Wang, P. and Zhang, D. Biosensors and Bioelectronics 55, (2014), 289-293.

Figure 1
A Novel Approach for the Preparation of Carbon Supported Intermetallic Cu3sn Nanoparticles and Their Electrocatalytic Performance for CO2 Reduction
Authors: Liu Yubin , Gunji Takao , Tanabe Toyokazu , Kaneko Shingo , Ohsaka Takeo , Miyauchi Masahiro , Matsumoto Futoshi 
Published: February 2020

Carbon supported ordered intermetallic Cu3Sn nanoparticles (NPs), which had a Cu3Ti type structure (1), was successfully prepared through a wet-chemical method (2) using lithium triethylborohydride as reducing agent. The prepared ordered intermetallic Cu3Sn was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electronic microscope (TEM). Cu3Sn intermetallic structure not only showed a higher electrocatalytic activity towards CO2 electrochemical reduction, but also selectively converted CO2to CO, compared with pure Cu NPs.
Figure 1 allows us to confirm the crystal structure of intermetallic Cu3Sn, disordered Cu-Sn alloy and pure Cu NPs, respectively. The main diffraction peaks of Cu NPs and disordered Cu-Sn alloy can be observed which are assigned as FCC-type structure while the XRD pattern of intermetallic NPs shows a good fit with stoichiometric Cu3Sn structure based on Cu3Ti-type lattice (1). Figure 2 shows the Faradaic efficiency (FE) for gaseous products which was evaluated in CO2 reduction for intermetallic Cu3Sn under the potential varying from -0.8 V to -1.6 V vs.RHE. It is suggested that the FE of CO production reaches the highest value of 40 % at -1.4 V, while the FE of hydrogen production is suppressed under 17%.
[1] Y. Watanabe, et al., Acta Cryst., B39, 1983, 306-311.
[2] F. Wang. et al., J. Alloys Comp., 439, 2007, 249–253.

Figure 1
Work Function Extraction of Indium Tin Oxide Used As Transparent Gate Electrode for Mosfet
Authors: Nehate Shraddha , Sundaram Kalpathy B 
Published: February 2020

Recent commercialization has peaked interest in transparent conducting oxides being implemented in display technology. Indium Tin Oxide (ITO) is a popular transparent conducting oxide which has been utilized as high work function electrode in liquid crystal displays, solar cells, gas sensors and heat reflecting films. Indium Tin Oxide films exhibit excellent transmission characteristics in the visible and infrared spectrum while maintaining high electrical conductivity. High work function electrodes are used to inject holes into organic materials. In majority applications the ITO work function has an impact on the device performance as it affects the energy barrier height at the hetero-junction interface. Hence, the work function of ITO is of critical importance.
In this article, we discuss work function extraction of ITO from a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) device for the first time. Two MOSFET devices are fabricated using a four level mask under identical conditions. Aluminum metal is used as a drain and source contact for both MOSFETs. One of the MOSFET has aluminum gate contact and transparent conducting ITO is used as gate contact for the second MOSFET. From the threshold voltage equation of both the fabricated MOSFETs, work function of ITO is extracted. Further optical transmission studies of ITO performed in the visible spectra are also reported in this study.
Electrodeposition of Compositionally Modulated Nife Alloys in Porous Anodic Alumina
Authors: Ramsey Keaton M. , Sides William D. , Huang Qiang 
Published: February 2020

Since the discovery of hexagonally self-ordered pore arrays in anodized of aluminum oxide (AAO)1, great strides have been made not only in understanding the mechanistic underpinnings of pore formation2-4
but also refinements to improve in the uniformity of arrays produced and enhance control over pore sizes5-8. Much interest in these arrays stems from their potential applications in microfabrication processes. AAO membranes have been used as templates in the production of nanowires through electrodeposition of metals, alloys, and nanostructured alloys9-13.
This paper presents a systematic study investigating the development of NiFe compositionally modulated nanowires for applications in biomedical devices. AAO membranes with different pore sizes were obtained with different electrolytes to fabricate nanowires with different diameters. Compositional modulation in NiFe alloy nanowires were created using double pulse scheme in electrodeposition. In addition, pulse schemes with different ramping schemes are used to create different compositional transitions between the modulations, which is characterized and verified using transition electron microscope with energy dispersive x-ray spectrometer. The anomalous interaction between Ni and Fe will be discussed in conjunction with the ramping pulse schemes and the ionic diffusion in the pores to explain the compositional profile along the wires.
References:
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2. O. Jessensky, F. Müller and U. Gösele, Journal of the Electrochemical Society
145(1998).
3. J. E. Houser and K. R. Hebert, Nature materials
8(2009).
4. Ö. Ö. Çapraz, P. Shrotriya, P. Skeldon, G. E. Thompson and K. R. Hebert, Electrochimica Acta
159(2015).
5. H. Masuda, K. Kanezawa and K. Nishio, Chemistry Letters(2002).
6. O. Jessensky, F. Müller and U. Gösele, Applied Physics Letters
72(1998).
7. S. Z. Chu, K. Wada, S. Inoue, M. Isogai and A. Yasumori, Advanced Materials
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20(2010).
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10. J. Garcıa, A. Asenjo, J. Velazquez, D. Garcıa, M. Vázquez, P. Aranda and E. Ruiz-Hitzky, Journal of Applied Physics
85(1999).
11. W. Schwarzacher, O. Kasyutich, P. Evans, M. Darbyshire, G. Yi, V. Fedosyuk, F. Rousseaux, E. Cambril and D. Decanini, Journal of magnetism and magnetic materials
198(1999).
12. P. Evans, G. Yi and W. Schwarzacher, Applied Physics Letters
76(2000).
13. Q. Huang, D. Davis and E. Podlaha, Journal of Applied Electrochemistry
36 (2006).
Comparison of Electropolishing Behavior of Two Grades of Brass Alloys
Authors: Rotty Chloé , Mandroyan Audrey , Doche Marie-Laure , Hihn Jean-Yves 
Published: February 2020

Brasses are widely used in watch manufacturing and jewelry as based materials, thanks to their cost, good mechanical properties and corrosion resistance. These industrial sectors face major changes in substrate composition in particular due to environmental regulations (changes in the grade of lead-free brass substrates) leading to investigate other brass grades.
Smooth and bright surfaces are usually obtained by mechanical polishing requiring a succession of manual operations. Electropolishing is an anodic dissolution process currently used in industries to replace mechanical polishing entirely or as a finishing treatment for complex shapes. The first patent for copper polishing in an aqueous orthophosphoric acid solution at high current density, was deposited by Jacquet in the 30s (1). The electropolishing quality depends on the material/electrolyte pair and the operating conditions (potential, time process, temperature…) (2,3).
The aim of this work is to observe the impact of alloying composition on polishing quality. Two grades of brass were used CuZn42 which has a diphasic composition, and CuZn37 which has a monophasic composition. They were electropolished in a phosphoric acid solution using a rotating disk electrode. At first, an electrochemical study was performed to investigate the electropolishing mechanism. A kinetic dependence on diffusion following the Levich law, is verified for the two grades of brass. This electrochemical study also allows to determine the best treatment conditions which correspond to the middle of electropolishing current density plateau.
The quality of polishing was evaluated by surface characterization which consists of a set of methods (Stylus Profiler, Secondary Electron Microscopy, Atomic Force Microscopy, X-Ray Diffraction). SEM and AFM images highlight a discrepancy between the two grades of brass (Figure 1). Indeed, CuZn37 sample (monophasic composition) shows a smooth surface and grain boundaries are almost not visible, while CuZn42 sample still presents a biphasic composition with a slight level difference between α and β phases. The roughness parameter Ra confirmed this behavior difference. Because CuZn37 sample presents a roughness equal to 42 nm, while CuZn42 is about 10 times rougher. All these characterization results indicate that there is a preferential attack of β phase (richer in Zn) for biphasic materials which induces some difficulties to apply standard conditions for the electropolishing process.
1. Jacquet PA. Electrolytic Method for obtaining Bright Copper Surfaces. Nature. 1935;135:1076.
2. Lin C-C, Hu C-C, Tai-Chou Lee. Electropolishing of 304 stainless steel interactive effects of glycerol content bath temperature and current density on surface roughness and morphology. Surf. Coat. Tech. 2009;448-54.
3. Gabe DR. Electropolishing of copper and copper-based alloys in ortho-phosphoric acid. Corros Sci. 1972;12:113-20.

Figure 1
PV Absorber Layered Materials Formation Using Potential Pulse Atomic Layer Deposition (PP-ALD),
Authors: Sisk Peter W , Czerniawski Justing , Stickney John Lewellen 
Published: February 2020

Thin film photovoltaic solar cells are a promising avenue for solar technology. However, they currently are not as cost effective as fossil fuels. Several absorber layer materials have been formed using various methods in the past. CuIn(1-x)GaxSe2(CIGS) is a promising material due to its tunable direct bandgap, allowing thin films to be used in photovoltaic devices.
Previous studies of CIGS done by the author’s group investigated thin film deposition using electrochemical atomic layer deposition (E-ALD). Potential Pulse Atomic Layer Deposition (PP-ALD) is an electrochemical method of atomic layer deposition that relies on alternating cathodic and anodic potential pulses. Cathodic potential pulses long enough to form fractions of a monolayer are used. This is followed by an anodic potential which makes use of the underpotential deposition (UPD) phenomenon to strip away excess bulk, allowing stoichiometric deposits. Because short pulses are used, there is not enough time for excess elemental layers to be formed. PP-ALD is also a one solution co-electrodeposition technique. This differs from the previous E-ALD, which required multiple solution switching, allowing for PP-ALD to have shorter deposition cycles, saving solution and time. Initial results for the formation of In2Se3 and other components of the CIGS compound will be discussed.