Enhancing dispersion stability of alpha-tocopherol in aqueous media using maize starch and ultrasonication

Ren, C.,Park, E.Y.,Kim, J.Y.,Lim, S.T. Academic Press, etc 2016 FOOD SCIENCE AND TECHNOLOGY -ZURICH- Vol.68 No.-

<P>Alpha-tocopherol (30-120 mg) was dispersed in an aqueous maize starch solution (0-240 mg starch solids in 30 mL) at various temperatures (60-80 degrees C) for 3 h, followed by cooling to 30 degrees C for different periods (0-12 h). The dispersion prepared under an optimized condition was subjected to ultrasonic treatment (up to 5 min in ice bath) to enhance the dispersion stability. When an aqueous a-tocopherol (60 mg) dispersion in a starch solution (120 mg in 30 mL) was prepared at 70 degrees C with cooling for 3 h and ultrasonic treatment for 3 min, a homogenous and opaque dispersion was obtained with 74% (w/w) of the a-tocopherol added was stably dispersed. The ultrasonic treatment decreased hydrodynamic diameter (from 1253 to 416 nm) and zeta-potential (from 6.28 to 22.40 mV) of the dispersed alpha-tocopherol particles, improving the dispersion stability. During a storage for 28 days at room temperature, the dispersion remained stable without producing any precipitates or aggregates. When the alpha-tocopherol dispersion in starch solution was subjected to autoclave treatment (121 degrees C for 20 min), 25% of the alpha-tocopherol in the dispersion was transformed to immiscible phase and phase-separated. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Ultrasonic-dispersed SAC 305 nanocomposite solder for mini LED bonding with high-temperature aging resistance

Sri Harini Rajendran,Cho Do Hoon,Seong Min Seo,Jae Pil Jung 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.11

Mini LED is one of the key technologies for 2019 and now making its way into display of consumer electronics. Sn-Ag-Cu solders received noticeable attention for flexible electronics due to their excellent creep resistance and thermal fatigue properties. However, the growth of Cu-Sn intermetallic compounds (IMC) at the interface during aging seriously impacts the solder joint’s mechanical properties. With the continuous miniaturization in the size of the solder joints, the impact of IMC growth is getting highly influential on the reliability of the solder joints. Recently, nanoparticles are added to the solder alloy to refine the microstructure and retard the growth of IMC at the interface and improve the solder joints’ reliability. The main limitation being the dispersion of nanoparticles in the solder alloy. Presently, nanoparticle dispersion by powder mixing is a widely used method. The main drawback in the powder mixing technique is that approximately only 20-30% of the added NPs are retained in the solder joint after reflow, and the rest are segregated along the edges. These segregated nanoparticles remain a threat as they can initiate the bridging of the solder in fine-pitch interconnections such as mini LED bonding. Therefore, it is necessary to move on to techniques wherein nanoparticles are in-situ dispersed during atomization of the solder balls. One such method is the ultrasonic dispersion of nanoparticles in the solder alloy. The present work attempts to make a comparative study between the conventional dispersion (CD) and ultrasonic dispersion (UD) of ZnO nanoparticles in Sn3.0Ag0.5Cu (SAC 305) solder alloy. The results show that UD has improved the wetting property of the solder alloy compared to CD. Also, the microstructure of UD exhibits higher refinement as compared to CD. More importantly, UD-SAC 305 solder displayed slower grain growth during high-temperature aging, thereby retaining higher tensile strength. The findings can be potential use for solder paste industries to develop in-situ nanoparticle reinforced type 6 and type 7 solder balls used in futuer for micro LED soldering.

Dispersion Behavior and Size Analysis of Thermally Purified High Pressure-high Temperature Synthesized Nanodiamond Particles

Kwon, Hansang,Park, Jehong,Leparoux, Marc The Korean Powder Metallurgy Institute 2017 한국분말재료학회지 (KPMI) Vol.24 No.3

Synthesized monocrystalline nanodiamond (nD) particles are heat-treated at various temperatures to produce highly structured diamond crystals. The heat-treated nDs show different weight loss ratios during thermogravimetric analysis. The crystallinities of the heat-treated nDs are analyzed using Raman spectroscopy. The average particle sizes of the heat-treated nDs are measured by a dynamic light scattering (DLS) system and direct imaging observation methods. Moreover, individual dispersion behaviors of the heat-treated nD particles are investigated based on ultrasonic dispersion methods. The average particle sizes of the dispersed nDs according to the two different measurement methods show very similar size distributions. Thus, it is possible to produce highly crystallized nD powder particles by a heat-treatment process, and the nD particles are relatively easy to disperse individually without any dispersant. The heat-treated nDs can lead to potential applications such as in nanocomposites, quantum dots, and biomedical materials.

초음파 분산을 이용한 Epoxy-Organoclay 나노콤포지트 구조적 그리고 유전특성에 관한 연구

朴材俊(Jae-Jun Park) 대한전기학회 2008 전기학회논문지 Vol.57 No.9

The effect of the organoclay_10A nanoparticles on the DSC and Structural and Dielectrics Propertiest(1㎐-1㎒) for epoxy/Organoclay_10A Nanocomposites has been studied. Dielectric properties of epoxy-Organoclay nanocomposites were investigated at 1, 3, 5, 7, 9 filler concentration by weight. Epoxy nanocomposites samples were prepared with good dispersion of layered silicate using power ultrasonic method in the particles. As structural analysis, the interlayer spacing have decreased with filled nanoparticles contents increase using power ultrasonic dispersion. The maximum increase interlayered spacing was observed to decease for above 5wt% clay loading. The other hand, as decrease with concentration filler of the layered silicate were increased dispersion degree of nanoparticles in the matrix. The interesting dielectric properties for epoxy based nanocomposites systems are attributed to the large volume fraction of interfacesin the bulk of the material and the ensuring interactions between the charged nanoparticle surface and the epoxy chains.

Nondestructive tests for defections detection of nanoparticles in cement-based materials: A review

Kaloop, Mosbeh R.,Elrahman, Mohamed Abd,Hu, Jong Wan Techno-Press 2022 Advances in nano research Vol.12 No.1

To date, nondestructive tests (NDT) applications and advances in detecting the dispersion and defections of the nano concrete (NC) materials fields are very limited. The current paper provides a review of the dispersion efficiency of nanomaterials in cement-based materials and how NDT can be efficiently used in detecting and visualizing the defections and dispersions of NC. The review identifies the characteristics of different types of nanoparticles used in NC. Nanomaterials influences on concrete characteristics and their dispersion degree are presented and discussed. The main aim of this article is to present and compare the common NDT that can be used for detecting and visualizing the defections and dispersions of different kinds of nanomaterials utilized in NC. The different microscopy and X-ray methods are explicitly reviewed and compared. Based on the collected data, it can be concluded that the fully detecting and visualizing of NC defections and dispersions have not been fully discovered and that needs further investigations. So, the distinction of this paper lies in defining NDT that can be employed for detecting and/or visualizing NC defections and dispersions.

압전체를 이용한 약품 분사용 초음파 분사 노즐 시스템

고재석,김용현,김형수,조순행,최승철 한국마이크로전자및패키징학회 2003 마이크로전자 및 패키징학회지 Vol.10 No.4

압전 세라믹스를 이용하여 약품 분사용 초음파분사 노즐을 제작하였다. 정수장의 혼화 공정에 사용되는 약품(응집제)의 고효율 분산을 위해 분사 노즐을 설계하였으며 압전세라믹을 최적화하였다. 제작된 초음파 약품 분사 노즐을 패키징하여 정수장의 약품 혼화 과정에 적용하여 약품사용의 고 효율화와 사용량 저감을 위한 연구를 진행하였다. 압전체는 실리콘으로 마감처리를 하였으며 Al으로 패키징하였다. 본 초음파 분사 노즐 시스템을 적용하여 혼화지에 실험한 결과 약품의 순간 혼화를 촉진시키는 기술로 투입 약품량을 저감시킬 수 있을 것으로 판단된다. 초음파 발진 약품 분사시, 무발진과 비교하여 대장균 제거 효율에서 현저하게 높아졌다. A new type of ultrasonic spray nozzle was fabricated employing a piezoelectric device. The spray nozzle was designed to disperse chemicals in a water treatment mixing tank. The piezoelectric properties in ultrasonic spray nozzles were optimized to improve the dispersion of chemicals. The piezoelectrics were packaged in an aluminum case with silicone resin for the aqueous solution proof packaging. Chemicals were dispersed with high efficiency and the chemicals consumption was reduced by the ultrasonic fine particle spraying. The concentration of Escherichia coli in mixing tank was decreased remarkably using ultrasonic spray nozzle dispersion compared to the conventional methods.

자기테이프용 Metal Powder의 초음파 분산에 의한 자기적 특성 향상에 관한 연구

김창곤,최현승,장학진,윤석영,김태옥,Kim, Chang-Gon,Choe, Hyeon-Seung,Jang, Hak-Jin,Yun, Seok-Yeong,Kim, Tae-Ok 한국재료학회 2001 한국재료학회지 Vol.11 No.11

It was investigated the effect of ultrasonic treatment on magnetic property of ultra fine magnetic Fe powders ($\alpha$-Fe) for magnetic tape. The properties were characterized with vibrating sample magnetometer (VSM), particle size analyzer (PSA) and scanning electron microscope (SEM). At 4hours ultrasonic treatment of 70 kHz, magnetic properties such as squareness ratio (S.Q. : 0.8868), orientation ratio (O.R. : 2.45) and switching field distribution (S.F. D. : 0.394) before taping were relatively enhanced. Cumulative particle size distribution of less than 5$\mu\textrm{m}$ fine powder was above 90% below 1 hour leaving time after ultrasonic treatment and it was supposed that ultrasonic treatment prevent aggregation. The magnetic values of S.Q. and S.F.D. of tape manufactured at 70 kHz and 4hour ultrasonic treatment were improved from 0.7747, 0.3818 to 0.8037, 0.3706, respectively. Electro-magnetic property used as in-output signal characteristic was improved, which showed that ultrasonic treatment developed the magnetic properties.

초음파 분산에 의한 수직자기기록용 Ba-ferrite의 자기적 특성 향상

최현승,김창곤,장학진,정지형,윤석영,김태옥,Choi, Hyun-Seung,Kim, Chang-Gon,Jang, Hak-Jin,Jung, Ji-Hyung,Yoon, Seog-Young,Kim, Tae-Ok 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.8

The various ultrasonic energies (28 kHz, 40 kHz, 70 kHz) were used to improve the magnetic properties of Ba-ferrite as the perpendicular magnetic recording materials. In the sheet formation process, the different orientation hars were used to orientate perpendicularly the dispersed Ba-ferrite to sheet. Throughout these experiments, we have obtained relatively higher value of S. Q. (Squreness Ratio : 0.783) and O. R. (Orientation Ratio : 2.87) magnetic properties at 2 h ultrasonic treatment of 40 kHz ultrasonic energy. With aid of SEM(Scanning Electron Microscopy) images, the obtained sheet with dispersed of Ba-ferrite could be used for perpendicular magnetic recording due to orientated to easy magnetization axis, c-axis. In addition, the value of S. Q. of sheet decreased with increasing applied magnetic field angle during measuring of S. Q. value with changing applied magnetic field angle by VSM (Vibrating Sample Magnetrometer). This result also induced the probability for prependicular magnetic recording. 초음파 에너지(28 kHz, 40 kHz, 70 kHz)를 사용하여 수직자기기록용 Ba-ferrite의 자기적 특성 향상에 대하여 조사하였다. 한편, 분산된 Ba-ferrite를 sheet에 수직으로 배향시키기 위해 다양한 형태의 배향기들을 사용하여 실험을 행하였다. Ba-ferrite가 도포된 sheet 중 초음파 에너지가 40 kHz이고 초음파 처리 시간이 2시간에서 자기적 특성인 S. Q. (Squareness Ratio)와 O. R. (Orientation Ratio)값이 각각 0.7831과 2.87로 비교적 좋은 값을 얻을 수 있었다. 이때 얻어진 sheet의 표면 형상을 SEM(Scanning Electron Microscopy)으로 분석한 결과 Ba-ferrite가 자화용이축인 c 축에 수직방향으로 배향되어 수직자기기록용으로서의 응용에 가능성을 보였다. 또한, VSM(Vibrating Sample Magnetometer)으로 자기장의 각도변화에 따른 S. Q.의 측정시, 자기장의 각도가 증가함에 따라 S. Q. 값이 감소하였고 이는 수직자기기록용으로써 가능성을 재확인 시켜주었다.

흠집 없는 h-MoO3 나노막대의 용이한 합성법

박소현,김기출 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.5

Molybdenum trioxide (MoO3) is an n-type semiconductor material having a wide bandgap energy of 2.5 ~ 3.2 eV. It finds application in various fields, such as photocatalysts, lithium-ion batteries, supercapacitors, and gas sensors. Among these, photocatalysts have received a lot of attention for their ability to remove organic pollutants in the air as well as in wastewater. In this study, flaw-free hexagonal molybdenum trioxide (h-MoO3) nanorods (NRs) were synthesized using the hydrothermal process. To synthesize h-MoO3 NRs, the precursor of ammonium heptamolybdate tetrahydrate (AHM) was dissolved in deionized water using two different dispersion methods. Nitric acid was then added to this reaction solution with stirring. Hydrothermal synthesis proceeded at 85oC for 60 minutes. The precipitate was filtered using a micro-membrane and dried in a vacuum oven. The morphology of the MoO3 NRs was analyzed using a field emission scanning electron microscope. The crystallographic properties of MoO3 NRs were characterized by Raman spectroscopy and X-ray diffraction. The results showed that flaw-free h-MoO3 NRs were synthesized uniformly by the ultrasonic dispersion method. On the other hand, the stirring dispersion method produced irregular-sized NRs with flaws. The uniform flaw-free h-MoO3 NRs produced by the ultrasonic dispersion method are expected to be used in high-efficiency visible light photocatalyst applications due to their uniform size and fine structure. MoO3는 2.5 ~ 3.2 eV의 넓은 밴드갭 에너지를 갖는 n형 반도체 소재로서, 광촉매, 리튬이온전지, 슈퍼커패시터, 가스센서 등 다양한 분야에 응용되고 있다. 그 중 광촉매는 폐수뿐만 아니라 공기 중의 유기 오염물을 제거하는 응용으로서 특히 주목을 받고 있다. 본 연구에서는 흠집없는 h-MoO3 나노막대를 수열합성 공정으로 합성하였다. h-MoO3 나노막대를 합성하기 위하여 전구체 AHM(Ammonium Heptamolybdate Tetrahydrate)을 탈이온수에 두 가지 분산 방법으로 용해시킨 후, 질산을 첨가하여 교반하였다. 85 oC에서 60분 동안 수열합성을 진행하였고, 침전물을 마이크로 멤브레인으로 걸러내고 진공오븐에서 건조하였다. 합성된 MoO3 나노막대의 표면형상을 전계방출형 주사전자현미경으로 분석하였고, MoO3 나노막대의 결정학적 특성을 Raman 분광법과 X선 회절법(XRD)으로 분석하였다. 분석결과, 초음파 분산기를 이용하면 흠집없는 h-MoO3 나노막대가 균일하게 합성되었다. 반면에 교반기 분산법을 사용하면 다수의 흠집을 갖고 있는 불규칙적인 크기의 h-MoO3 나노막대가 합성되었다. 초음파 분산기를 이용하여 균일하고 흠집없이 합성된 h-MoO3 나노막대는 균일한 크기와 미세한 구조를 갖고 있기 때문에 높은 효율의 가시광선 광촉매 응용에 활용될 수 있을 것으로 기대된다.

금속 박막의 유도초음파 분산 특성 연구

김미소(Miso Kim),조승현(Seung Hyun Cho),장강원(Gang-Won Jang),이승석(Seung-Seok Lee),박익근(Ik-Keun Park) 한국비파괴검사학회 2014 한국비파괴검사학회지 Vol.34 No.3

나노/마이크로 소자의 개발이 활발해짐에 따라 나노/마이크로 박막의 기계적 물성의 정밀 측정에 대한 필요성이 점차 커지고 있다. 기존의 파괴적인 방법의 한계를 극복하기 위한 방법으로, 유도초음파를 이용한 비파괴적인 박막 물성 방법에 대한 관심이 늘어나고 있다. 유도초음파를 이용하여 박막의 물성을 측정하는 실험을 설계하거나, 물성 측정에 대한 실험 결과를 이해하는데 있어 박막의 분산선도를 이해하는 것은 필수적이라 할 수 있다. 본 연구에서는, 전달 행렬법을 이용하여 박막의 분산선도를 계산하는 방법을 제시하고, 이를 금속 박막에 적용하여 그 특성을 관찰하였다. 전달 행렬법을 이용하여 다층판에서의 주파수에 따라 유도초음파가 전파하는 속도를 계산하여 상용 프로그램과 비교하여 그 타당성을 확인하였다. 이러한 방법을 Si 기판 위에 증착된 Al 금속 박막에 적용하여 얻은 분산곡선의 분석을 통해, 박막의 두께 조건에 따른 모드와 분산 및 비분산 특성이 나타나는 구간을 관찰할 수 있었다. In this study, we investigated the dispersion characteristics of guided waves in thin films. Dispersion curves are essential for understanding not only the behavior of ultrasonic waves, but also the mechanical properties of thin films. Matrix techniques are presented for modeling ultrasonic waves in multilayered structures before being used to calculate the dispersion curves for Al-steel and Al-composite specimens. When compared with the dispersion curves obtained using the commercial program (Disperse), the dispersion curves generated from the transfer matrix method show its validity. These developed methods are used to obtain dispersion curves for Al thin films deposited on a Si substrate. The resulting dispersion curves enable observation of both dispersive and nondispersive behavior for the guided waves, depending on the thickness of the thin films.