Most commercially available detonation nanodiamonds (DNDs) require further processing to qualify for use in biomedical applications, as they often contain many impurities and exhibit poor dispersibility in aqueous media. In this work, DNDs are modified to improve purity and impart a high colloidal stability to the particles. The dispersive and adsorption properties of modified DNDs are evaluated in terms of the suitability of DNDs as carriers for non-steroidal anti-inflammatory drugs (NSAIDs) in transdermal delivery. The study of adsorption on strongly positively and strongly negatively charged DNDs showed their high loading capacity for NSAIDs, and a pronounced relationship between the drugs and the particles’ charges. Experiments on long-term desorption carried out with DND/NSAID complexes indicate that the nanoparticles exert a sustained effect on the drug release process.

The high theoretical energy density (2600 Wh kg⁻¹) of Lithium-sulfur batteries and the high theoretical capacity of elemental sulfur (1672 mAh g⁻¹) attract significant research attention. However, the poor electrical conductivity of sulfur and the polysulfide shuttle effect are chronic problems resulting in low sulfur utilization and poor cycling stability. In this study, we address these problems by coating a polyethylene separator with a layer of activated carbon powder. A lithium-sulfur cell containing the activated carbon powder-coated separator exhibits an initial specific discharge capacity of 1400 mAh g⁻¹ at 0.1 C, and retains 63% of the initial capacity after 100 cycles at 0.2 C, whereas the equivalent cell with a bare separator exhibits a 1200 mAh g⁻¹ initial specific discharge capacity, and 50% capacity retention under the same conditions. The activated carbon powder-coated separator also enhances the rate capability. These results indicate that the microstructure of the activated carbon powder layer provides space for the sulfur redox reaction and facilitates fast electron transport. Concurrently, the activated carbon powder layer traps and reutilizes any polysulfides dissolved in the electrolyte. The approach presented here provides insights for overcoming the problems associated with lithium-sulfur batteries and promoting their practical use.

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• A one-step deposition method to prepare separators with carbon soot loading for lithium-sulfur battery
  Yueting Zhu, Jingjing Wang, Yanshu Wang, Ying Zhu, Yixuan Li, Shicheng Zhao
  Ionics.2022; 28(4): 1693.     CrossRef
• High thermal stability multilayered electrolyte complexes via layer-by-layer for long-life lithium-sulfur battery
  Jing Wang, Yufan Li, Xianmei Deng, Lei Yan, Zhiqiang Shi
  Ionics.2020; 26(11): 5481.     CrossRef

Selective laser melting (SLM), a type of additive manufacturing (AM) technology, leads a global manufacturing trend by enabling the design of geometrically complex products with topology optimization for optimized performance. Using this method, three-dimensional (3D) computer-aided design (CAD) data components can be built up directly in a layer-by-layer fashion using a high-energy laser beam for the selective melting and rapid solidification of thin layers of metallic powders. Although there are considerable expectations that this novel process will overcome many traditional manufacturing process limits, some issues still exist in applying the SLM process to diverse metallic materials, particularly regarding the formation of porosity. This is a major processing-induced phenomenon, and frequently observed in almost all SLM-processed metallic components. In this study, we investigate the mechanical anisotropy of SLM-produced 316L stainless steel based on microstructural factors and highly-oriented porosity. Tensile tests are performed to investigate the microstructure and porosity effects on mechanical anisotropy in terms of both strength and ductility.

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• Development of multi-defect diagnosis algorithm for the directed energy deposition (DED) process with in situ melt-pool monitoring
  Hyewon Shin, Jimin Lee, Seung-Kyum Choi, Sang Won Lee
  The International Journal of Advanced Manufacturing Technology.2023; 125(1-2): 357.     CrossRef
• Corrosion Resistance of Laser Powder Bed Fused AISI 316L Stainless Steel and Effect of Direct Annealing
  Kichang Bae, Dongmin Shin, Jonghun Lee, Seohan Kim, Wookjin Lee, Ilguk Jo, Junghoon Lee
  Materials.2022; 15(18): 6336.     CrossRef
• Experimental investigation on the effect of process parameters in additive/subtractive hybrid manufacturing 316L stainless steel
  Chengming Tang, Jibin Zhao, Zhiguo Wang, Yuhui Zhao, Tianran Wang
  The International Journal of Advanced Manufacturing Technology.2022; 121(3-4): 2461.     CrossRef
• Interface characteristics and mechanical behavior of additively manufactured multi-material of stainless steel and Inconel
  Man Jae Sagong, Eun Seong Kim, Jeong Min Park, Gangaraju Manogna Karthik, Byeong-Joo Lee, Jung-Wook Cho, Chong Soo Lee, Takayoshi Nakano, Hyoung Seop Kim
  Materials Science and Engineering: A.2022; 847: 143318.     CrossRef
• Effect of heat treatment on microstructural heterogeneity and mechanical properties of 1%C-CoCrFeMnNi alloy fabricated by selective laser melting
  Jeong Min Park, Eun Seong Kim, Hyeonseok Kwon, Praveen Sathiyamoorthi, Kyung Tae Kim, Ji-Hun Yu, Hyoung Seop Kim
  Additive Manufacturing.2021; 47: 102283.     CrossRef
• Manufacturing Aluminum/Multiwalled Carbon Nanotube Composites via Laser Powder Bed Fusion
  Eo Ryeong Lee, Se Eun Shin, Naoki Takata, Makoto Kobashi, Masaki Kato
  Materials.2020; 13(18): 3927.     CrossRef
• Effects of microstructure and internal defects on mechanical anisotropy and asymmetry of selective laser-melted 316L austenitic stainless steel
  Jin Myoung Jeon, Jeong Min Park, Ji-Hun Yu, Jung Gi Kim, Yujin Seong, Sun Hong Park, Hyoung Seop Kim
  Materials Science and Engineering: A.2019; 763: 138152.     CrossRef
• Microstructural effects on the tensile and fracture behavior of selective laser melted H13 tool steel under varying conditions
  Jungsub Lee, Jungho Choe, Junhyeok Park, Ji-Hun Yu, Sangshik Kim, Im Doo Jung, Hyokyung Sung
  Materials Characterization.2019; 155: 109817.     CrossRef

Despite numerous advances in the preparation and use of GaN, and many leading-edge applications in lighting technologies, the preparation of high-quality GaN powder remains a challenge. Ammonolytic preparations of polycrystalline GaN have been studied using various precursors, but all were time-consuming and required high temperatures. In this study, an efficient and low-temperature method to synthesize high-purity hexagonal GaN powder is developed using sub-micron Ga₂O₃ powder as a starting material. The sub-micron Ga₂O₃ powder was prepared by an ultrasonic spray pyrolysis process. The GaN powder is synthesized from the sub-micron Ga₂O₃ powder through a nitridation treatment in an NH₃ flow at 800°C. The characteristics of the synthesized powder are systematically examined by X-ray diffraction, scanning and transmission electron microscopy, and UV-vis spectrophotometer.

The impact of different mixing methods and sintering temperatures on the microstructure and piezoelectric properties of PZNN-PZT ceramics is investigated. To improve the sinterability and piezoelectric properties of these ceramics, the composition of 0.13Pb((Zn_0.8Ni_0.2)_1/3Nb_2/3)O₃-0.87Pb(Zr_0.5Ti_0.5)O₃ (PZNN-PZT) containing a Pb-based relaxor component is selected. Two methods are used to create the powder for the PZNN-PZT ceramics. The first involves blending all source powders at once, followed by calcination. The second involves the preferential creation of columbite as a precursor, by reacting NiO with Nb₂O₅ powder. Subsequently, PZNN-PZT powder can be prepared by mixing the columbite powder, PbO, and other components, followed by an additional calcination step. All the PZNNPZT powder samples in this study show a nearly-pure perovskite phase. High-density PZNN-PZT ceramics can be fabricated using powders prepared by a two-step calcination process, with the addition of 0.3 wt% MnO2 at even relatively low sintering temperatures from 800°C to 1000°C. The grain size of the ceramics at sintering temperatures above 900°C is increased to approximately 3 μm. The optimized PZNN-PZT piezoelectric ceramics show a piezoelectric constant (d₃₃) of 360 pC/N, an electromechanical coupling factor (kp) of 0.61, and a quality factor (Q_m) of 275.

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• An Analysis of Edge Chipping in LiTaO3 Wafer Grinding Using a Scratch Test and FEA Simulation
  Haeseong Hwang, Seungho Han, Hyunseop Lee
  Lubricants.2023; 11(7): 297.     CrossRef
• A generalized rule for phase transition generated by additives in piezoelectric ceramics
  Jae-Min Cha, Young-Kook Moon, Jung-hwan Kim, Hyun-Ae Cha, Jong-Jin Choi, Byung-Dong Hahn, Seog-Young Yoon, Cheol-Woo Ahn
  Materials Today Communications.2023; 37: 107290.     CrossRef
• Low-Temperature Sintering Properties of Bi2O3 Doped PZT-5H Piezoelectric Ceramics
  Wanzi Mao, Qing Xu, Duanping Huang, Huajun Sun, Feng Zhang, Xiaobin Xie
  Journal of Electronic Materials.2023; 52(5): 3334.     CrossRef
• Effect of LiBiO2 on low-temperature sintering of PZT-PZNN ceramics
  Sung Cheul Hong, Shi Yeon Kim, Dong-Hun Yeo, Hyo-Soon Shin, Zee Hoon Park, Sahn Nahm
  Journal of the Korean Ceramic Society.2022; 59(5): 638.     CrossRef
• Two-Stage De-binding for Cu Electrode Application to PZT-PZNN Multilayer Actuator
  Sung Cheul Hong, Zeehoon Park, Dong-Hun Yeo, Hyo-Soon Shin, Sahn Nahm
  Transactions on Electrical and Electronic Materials.2022; 23(4): 348.     CrossRef

In this study, the effect of the content of MgO-CaO-Al₂O₃-SiO₂ (MCAS) glass additives on the properties of AlN ceramics is investigated. Dilatometric analysis and isothermal sintering for AlN compacts with MCAS contents varying between 5 and 20 wt% are carried out at temperatures ranging up to 1600°C. The results showed that the shrinkage of the AlN specimens increases with increasing MCAS content, and that full densification can be obtained irrespective of the MCAS content. Moreover, properties of the AlN-MCAS specimens such as microhardness, thermal conductivity, dielectric constant, and dielectric loss are analyzed. Microhardness and thermal conductivity decrease with increasing MCAS content. An acceptable candidate for AlN application is obtained: an AlN-MCAS composite with a thermal conductivity over 70 W/m·K and a dielectric loss tangent (tan δ) below 0.6 × 10⁻³, with up to 10 wt% MCAS content.

With the recent remarkable improvements in the average speeds of contemporary trains, a necessity has arisen for the development of new friction modifiers to improve adhesion characteristics at the wheel-rail interface. The friction modifier must be designed to reduce slippage or sliding of the trains’ wheels on the rails under conditions of rapid acceleration or braking without excessive rolling contact wear. In this study, a novel composite material consisting of metal, ceramic, and polymer is proposed as a friction modifier to improve adhesion between wheels and rails. A blend of Al-6Cu-0.5Mg metallic powder, Al₂O₃ ceramic powder, and Bakelite-based polymer in various weight-fractions is hot-pressed at 150°C to form a bulk composite material. Variation in the adhesion coefficient is evaluated using a high-speed wheel-rail friction tester, with and without application of the composite friction modifier, under both dry and wet conditions. The effect of varying the weighting fractions of metal and ceramic friction powders is detailed in the paper.

This study investigates the viability of using a Na-ion battery with a tin(Sn) anode to mitigate the vulnerability caused by volume changes during discharge and charge cycling. In general, the volume changes of carbon material do not cause any instability during intercalation into its layer structure. Sn has a high theoretical capacity of 847 mAh g⁻¹. However, it expands dramatically in the discharge process by alloying Na-Sn, placing the electrode under massive internal stress, and particularly straining the binder over the elastic limit. The repeating strain results in loss of active material and its electric contact, as well as capacity decrease. This paper expands the scope of fabrication of Na-ion batteries with Sn by fabricating the binder as an auxetic structure with a unique feature: a negative Poisson ratio (NPR), which increases the resistance to internal stress in the Na-Sn alloying/de-alloying processes. Electrochemical tests and micrograph images of auxetic and common binders are used to compare dimensional and structural differences. Results show that the capacity of an auxetic-structured Sn electrode is much larger than that of a Sn electrode with a common-structured binder. Furthermore, using an auxetic structured Sn electrode, stability in discharge and charge cycling is obtained.

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• Highly Flexible and Conductive Electrodes through Combining Honeycomb and Butterfly Pattern Bio‐Inspired Structure for ECG Signal Recording
  Qi Hou, Min Wang, Chunyang Han, Kuiyang Gao, Ruiyao Liu, Guofeng Yao
  Advanced Materials Interfaces.2022;[Epub]     CrossRef

Layered-double hydroxide (LDH)-based nanostructures offer the two-fold advantage of being active catalysts with incredibly large specific surface areas. As such, they have been studied extensively over the last decade and applied in roles as diverse as light source, catalyst, energy storage mechanism, absorber, and anion exchanger. They exhibit a unique lamellar structure consisting of a wide variety of combinations of metal cations and various anions, which determine their physical and chemical performances, and make them a popular research topic. Many reviewed papers deal with these unique properties, synthetic methods, and applications. Most of them, however, are focused on the form-factor of nanopowder, as well as on the control of morphologies via one-step synthetic methods. LDH nanostructures need to be easy to control and fabricate on rigid substrates such as metals, semiconductors, oxides, and insulators, to facilitate more viable applications of these nanostructures to various solid-state devices. In this review, we explore ways to grow and control the various LDH nanostructures on rigid substrates.

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• Review of Domestic Research Trends on Layered Double Hydroxide (LDH) Materials: Based on Research Articles in Korean Citation Index (KCI)
  Seon Yong Lee, YoungJae Kim, Young Jae Lee
  Economic and Environmental Geology.2023; 56(1): 23.     CrossRef