Aerodynamic and aeroelastic flutters driven triboelectric nanogenerators for harvesting broadband airflow energy

Phan, Hai,Shin, Dong-Myeong,Heon Jeon, Sang,Young Kang, Tae,Han, Pyunghwa,Han Kim, Gyu,Kook Kim, Hyung,Kim, Kyujung,Hwang, Yoon-Hwae,Won Hong, Suck Elsevier 2017 Nano energy Vol.33 No.-

<P><B>Abstract</B></P> <P>Aerodynamic and aeroelastic flutter-driven triboelectric nanogenerators are successfully used to harvest broadband airflow energy. The unit component of the flutter membrane consists of thin, free-standing Al foil electrodes covered on both sides with electrospun poly(vinyl chloride) nanofiber-structured mats, which provide advantageous tribo-surfaces specifically to increase the friction area. The airflow-induced triboelectric power generation from a single unit of the flutter-membrane-based triboelectric nanogenerator (FM-TENG) was up to 0.33 μW under a mild airflow condition. The use of a multi-layered triboelectric nanogenerator, fabricated by simply stacking the single units, can improve the output performance of the device. In a separate configuration, we designed a novel FM-TENG structure by mounting an aeroelastic flutter-belt adapted for use with a flutter-membrane energy-harvester. A rubber belt, which was sandwiched between the flutter membranes, created a rapid periodic vibrational mode via aeroelastic fluttering, synergistically harvesting triboelectric energy with the application of a constant air stream through the closed channel of the FM-TENG. Thus, our flutter-membrane-based approach creates a sustainable and cost-efficient energy harvesting system for collecting broadband airflow energy. Furthermore, the aerodynamic and aeroelastic FM-TENG have great potential to be used in numerous areas of self-powered electronic systems and in-situ wireless sensor applications for automobiles or aircraft.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Aerodynamic and aeroelastic flutter-driven triboelectric nanogenerators. </LI> <LI> Multi-layered triboelectric nanogenerators. </LI> <LI> Adapting an aeroelastic flutter to synergistically combine aerodynamic and aeroelastic movement. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>The harvest of broadband airflow energy is accomplished using aerodynamic and aeroelastic flutter-driven triboelectric nanogenerators. Multi-layered triboelectric nanogenerators are made by simply stacking single units and can improve the output performance of the device. Adapting an aeroelastic flutter to synergistically combine aerodynamic and aeroelastic movement enables dramatic improvements in the electrical output of the triboelectric nanogenerator.</P> <P>[DISPLAY OMISSION]</P>

Multi-Strain Probiotics Enhance the Bioactivity of Cascara Kombucha during Microbial Composition-Controlled Fermentation

Thach Phan Van,Quang Khai Phan,Hoa Pham Quang,Gia Bao Pham,Ngoc Han Ngo Thi,Hong Tham Truong Thi,Anh Duy Do 한국식품영양과학회 2023 Preventive Nutrition and Food Science Vol.28 No.4

Kombucha is a widely consumed fermented tea beverage with diverse health benefits. In a previous study, we demonstrated that the use of cascara as a substrate results in a special kombucha beverage with high bioactivity. Traditional kombucha fermentation using a symbiotic culture of bacteria and yeast (SCOBY) can lead to inconsistent product quality because of the lack of control over microbial composition. We successfully isolated and identified yeast and bacteria, including Saccharomyces cerevisiae, Komagataeibacter rhaeticus, and Lactobacillus brevis that are appropriate starter cultures for cascara kombucha fermentation. We also demonstrated that a supplementation with lactic acid bacteria (LAB) and a mixture of S. cerevisiae and K. rhaeticus resulted in higher total polyphenol and flavonoid content of cascara kombucha compared with the traditionally fermented product using SCOBY as the inoculum. The free radical scavenging activity, inhibitory effects on α-amylase, tyrosinase activity, and antibacterial properties of cascara kombucha were also enhanced as a result of LAB supplement. These findings provide valuable insights into the controlled microbiological composition required for the fermentation of cascara kombucha, thereby ensuring consistent quality and enhanced bioactivity of the product. Further, the use of cascara as a substrate for kombucha production not only offers various health benefits and biological effects, but also repurposes by-products from the coffee industry, which contributes to sustainable development and is eco-friendly.

Photoluminescence properties of Cr3+-doped MgAl2O4 Natural Spinel

The-Long Phan,Manh-Huong Phan,유성초,Thomas P J Han 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.1

We present, here, the results of a study of photoluminescence spectra of Cr3+-doped MgAl2O4 natural spinel in a given wavenumber range between 26,300 and 12,500 cm By using several excitation sources, we observed a new broadband, namely K, with a peak at 15,547 cm and the transition process of luminescence lines among the electronic levels of the Cr3+ ion, such as R, Ni (i = 1-4) lines. In terms of the experimental results and the conguration coordinates, we strongly propose that the K-band might originate from the electric dipole transition 2Eg ! 4A2g, in a strong crystal eld with Dq=B > 2:3. The decay-time and luminescence-rise-time curves on the zero-phonon lines and the K-band were also recorded.

Promoting the Consumption of Electric Vehicles: an Empirical Study in Vietnam

Cuong NGUYEN(Cuong NGUYEN ),Thao TRAN(Thao TRAN ),Khanh HA(Khanh HA ),Han PHAN(Han PHAN ) 한국유통과학회 2024 The Journal of Industrial Distribution & Business( Vol.15 No.3

Purpose: Electronic vehicles (EV) consumption become more prevalent among Vietnamese consumers. This paper aims to empirically assess the determinants of EV purchase intention among Vietnamese consumers. The research findings are expected to promote the consumption of electric vehicles in Vietnam. Research design, data and methodology: The quantitative research approach employed the Exploratory Factor Analysis (EFA). The sample size includes 301 respodents. Research design unified Theory of Acceptance and Use of Technology (UTAUT) and UTAUT2. The data collection process employ the non-probability sampling. Questionaire survey consists of 24 questions given to respondents via Google Form link. Data is processed by SPSS version 20 software. Results: The results proposed 04 determinants of the intention to buy electric vehicles: Government Support, Environmental Concern, Price Value, and Performance. Conclusions: Theorectical implications and managerial implications are also discussed to promote the consumption of electronic vehicles in Vietnam. Besides, the findings show that Price value, Environmental Concern and Performance positively affect the purchase intention of EV among Vietnamese consumers. Remarkably, Government Support is proven to be an insignificant factor in EV purchase intention. The call for further research rely on the role of government support in order to promote EV consumption in Vietnam and other emerging markets worldwide.

Platinum-catalyzed double silylations of alkynes with bis(dichlorosilyl)methanes

Phan, Son Thanh,Lim, Weon Cheol,Han, Joon Soo,Jung, Il Nam,Yoo, Bok Ryul Elsevier 2006 Journal of organometallic chemistry Vol.691 No.4

<P><B>Graphical abstract</B></P><P>Reaction of alkynes such as ethene (<B>2a</B>), phenylethene (<B>2b</B>); 1,2-diphenylethene (<B>2c</B>) with bis(dichlorosilyl)methanes RCH(SiHCl<SUB>2</SUB>)<SUB>2</SUB>: R=H (<B>1a</B>), SiMe<SUB><I>n</I></SUB>Cl<SUB>3−<I>n</I></SUB>: <I>n</I>=0 (<B>1b</B>), 1 (<B>1c</B>), 2 (<B>1d</B>), 3 (<B>1e</B>) in the presence of Speier’s catalyst gave one of two type products of 1,3-disilacyclopentanes <B>3</B> and 1,3-disilacyclopent-4-enes <B>4</B>. Reaction of <B>1a</B> with <B>2a</B>–<B>c</B> at 80°C gave compounds <B>3</B> in 33–84% yields. The reaction with <B>2c</B> gave <B>3ac</B> in the highest yield (84%). Reaction of <B>1b</B>–<B>e</B> with <B>2c</B> under the same conditions gave compounds <B>3</B> in 38–98% yields. The yields deceased in following order: <I>n</I>=1>2>3>0. Reactions of <B>1c</B> with simple <B>2a</B> and terminal <B>2b</B> under the same conditions gave <B>4ca</B> and <B>4cb</B> in 91% and 57% yields, respectively, while internal alkyne <B>2c</B> afforded <B>3cc</B> in 98% yield.</P><ce:figure></ce:figure> <P><B>Abstract</B></P><P>Bis(dichlorosilyl)methanes <B>1</B> undergo the two kind reactions of a double hydrosilylation and a dehydrogenative double silylation with alkynes <B>2</B> such as acetylene and activated phenyl-substituted acetylenes in the presence of Speier’s catalyst to give 1,1,3,3-tetrachloro-1,3-disilacyclopentanes <B>3</B> and 1,1,3,3-tetrachloro-1,3-disilacyclopent-4-enes <B>4</B> as cyclic products, respectively, depending upon the molecular structures of both bis(dichlorosilyl)methanes (<B>1</B>) and alkynes (<B>2</B>). Simple bis(dichlorosilyl)methane (<B>1a</B>) reacted with alkynes [R<SUP>1</SUP>–CC–R<SUP>2</SUP>: R<SUP>1</SUP>=H, R<SUP>2</SUP>=H (<B>2a</B>), Ph (<B>2b</B>); R<SUP>1</SUP>=R<SUP>2</SUP>=Ph (<B>2c</B>)] at 80°C to afford 1,1,3,3-tetrachloro-1,3-disilacyclopentanes <B>3</B> as the double hydrosilylation products in fair to good yields (33–84%). Among these reactions, the reaction with <B>2c</B> gave a <I>trans</I>-4,5-diphenyl-1,1,3,3-tetrachloro-1,3-disilacyclopentane <B>3ac</B> in the highest yield (84%). When a variety of bis(dichlorosilyl)(silyl)methanes [(Me<SUB><I>n</I></SUB>Cl<SUB>3−<I>n</I></SUB>Si)CH(SiHCl<SUB>2</SUB>)<SUB>2</SUB>: <I>n</I>=0 (<B>1b</B>), 1 (<B>1c</B>), 2 (<B>1d</B>), 3 (<B>1e</B>)] were applied in the reaction with alkyne (<B>2c</B>) under the same reaction conditions. The double hydrosilylation products, 2-silyl-1,1,3,3-tetrachloro-1,3-disilacyclopentanes (<B>3</B>), were obtained in fair to excellent yields (38–98%). The yields of compound <B>3</B> deceased as follows: <I>n</I>=1>2>3>0. The reaction of alkynes (<B>2a</B>–<B>c</B>) with <B>1c</B> under the same conditions gave one of two type products of 1,1,3,3-tetrachloro-1,3-disilacyclopentanes <B>3</B> and 1,1,3,3-tetrachloro-1,3-disilacyclopent-4-enes (<B>4</B>): simple alkyne <B>2a</B> and terminal <B>2b</B> gave the latter products <B>4ca</B> and <B>4cb</B> in 91% and 57% yields, respectively, while internal alkyne <B>2c</B> afforded the former cyclic products <B>3cc</B> with <I>trans</I> form between two phenyl groups at the 3- and 4-carbon atoms in 98% yield, respectively. Among platinum compounds such as Speier’s catalyst, PtCl<SUB>2</SUB>(PEt<SUB>3</SUB>)<SUB>2</SUB>, Pt(PPh<SUB>3</SUB>)<SUB>2</SUB>(C<SUB>2</SUB>H<SUB>4</SUB>), Pt(PPh<SUB>3</SUB>)<SUB>4</SUB>, Pt[ViMeSiO]<SUB>4</SUB>, and Pt/C, Speier’s catalyst was the best catalyst for such silylation reactions.</P>

Nootkatol prevents ultraviolet radiation-induced photoaging via ORAI1 and TRPV1 inhibition in melanocytes and keratinocytes

Joo Han Woo,Da Yeong Nam,Hyun Jong Kim,Phan Thi Lam Hong,Woo Kyung Kim,Joo Hyun Nam 대한약리학회 2021 The Korean Journal of Physiology & Pharmacology Vol.25 No.1

Skin photoaging occurs due to chronic exposure to solar ultraviolet radiation (UV), the main factor contributing to extrinsic skin aging. Clinical signs of photoaging include the formation of deep, coarse skin wrinkles and hyperpigmentation. Although melanogenesis and skin wrinkling occur in different skin cells and have different underlying mechanisms, their initiation involves intracellular calcium signaling via calcium ion channels. The ORAI1 channel initiates melanogenesis in melanocytes, and the TRPV1 channel initiates MMP-1 production in keratinocytes in response to UV stimulation. We aimed to develop a drug that may simultaneously inhibit ORAI1 and TRPV1 activity to help prevent photoaging. We synthesized nootkatol, a chemical derivative of valencene. TRPV1 and ORAI1 activities were measured using the whole-cell patch-clamp technique. Intracellular calcium concentration [Ca²⁺]i was measured using calcium-sensitive fluorescent dye (Fura-2 AM). UV-induced melanin formation and MMP-1 production were quantified in B16F10 melanoma cells and HaCaT cells, respectively. Our results indicate that nootkatol (90 μM) reduced TRPV1 current by 94% ± 2% at -60 mV and ORAI1 current by 97% ± 1% at -120 mV. Intracellular calcium signaling was significantly inhibited by nootkatol in response to ORAI1 activation in human primary melanocytes (51.6% ± 0.98% at 100 μM). Additionally, UV-induced melanin synthesis was reduced by 76.38% ± 5.90% in B16F10 melanoma cells, and UV-induced MMP-1 production was reduced by 59.33% ± 1.49% in HaCaT cells. In conclusion, nootkatol inhibits both TRPV1 and ORAI1 to prevent photoaging, and targeting ion channels may be a promising strategy for preventing photoaging.

LUXURY RETAIL SERVICES: WHAT DO CHINESE CONSUMERS EXPECT?

Michel Phan,Spring Han 글로벌지식마케팅경영학회 2017 Global Fashion Management Conference Vol.2017 No.07

The luxury industry worldwide, and in China in particular, has been going through some major shake-ups in the last few years, such as the impact of anti-corruption campaign in China since 2012, massive increase of Chinese out-bound tourists travelling abroad for shopping due to price advantages as compared to mainland China prices, changing customer preferences and low loyalty towards luxury brands, and heightened customer knowledge of luxury, to name a few. These changes have a direct impact on customers’ behavior and experience in luxury retail stores and ultimately the level of expectation and satisfaction they have with luxury brands. This paper aims to shed some light on this topic by focusing specially on Chinese luxury customers’ perspectives. Companies have considered customer experience as one of important ways to obtain and sustain competitive advantages. Zomerdijk and Voss (2009) maintained that customer experience is a holistic concept that encompasses every aspect of a company’s offering. However, it is unclear which service elements offered by company create the most compelling contexts. Chinese luxury customers represent one-third of the total personal luxury goods market by the end of 2016 according to Bain & Co (2016). Therefore, no luxury brand can afford to ignore Chinese customers and their level of satisfaction with their brands. Paradoxically, from 2012 to 2015, the luxury personal goods market in China has decreased by 1% or 2% each year as compared to the previous years. This was due to many factors, and one of them was “poor customer experience in retail stores” according to our study. This deceleration of the market in China has prompted many luxury brands to create new customer experiences that could increase satisfaction (such as made-to-order services) in order to retain existing customers and to gain new ones. The research questions of this paper are: what type of services do Chinese customers expect from luxury brands? What are the levels of satisfaction Chinese customers have with luxury brands abroad and in China? How can luxury bands improve their service experience offers to satisfy Chinese customers? In order to answer these questions, we carried out a longitudinal study over 4 years, from 2012 to 2015 with Chinese luxury customers. A Chinese luxury customer is defined as someone who has bought a genuine luxury product over the last 6 months, whether in China or abroad, for themselves or for someone else. Each year we interviewed 120 customers who were chosen randomly in the streets of Shanghai, nearby luxury malls. The interviews were carried out either in English (if they are comfortable of speaking in English) or in Mandarin (by a native speaker). The interviews lasted on average 30 minutes each. The questions are mostly open-ended questions such as: “Could you please tell us your best or worst experience in a luxury retail store, in China or abroad? And why is it the best or worst?”. The interviews were manually recorded by a second interviewer present at that time. The data were then compiled and analyzed for this paper. The findings of the study were somehow unexpected such as: 1- Chinese luxury customers expect very simple and basic services in luxury retail stores, such as a sincere smile and a warm welcome, or sales employees do not judge them based on their looks and appearances. 2- Retail staff should have a better and up-to-date product knowledge so they can answer simple questions about the products when asked. 3- Retail staff should be able to give good advice to customer when they are undecided, and not try push only sales. Managerial implications for luxury brands are many. However, the most important one by far is “to go back to the basics of retail customer experience” by selecting and training the right employees for the job.

Modularly engineered injectable hybrid hydrogels based on protein-polymer network as potent immunologic adjuvant <i>in vivo</i>

Giang Phan, V.H.,Duong, Huu Thuy Trang,Thambi, Thavasyappan,Nguyen, Thanh Loc,Turabee, Md. Hasan,Yin, Yue,Kim, Seong Han,Kim, Jaeyun,Jeong, Ji Hoon,Lee, Doo Sung IPC Science and Technology Press 2019 Biomaterials Vol.195 No.-

<P><B>Abstract</B></P> <P>Lymphoid organs, which are populated by dendritic cells (DCs), are highly specialized tissues and provide an ideal microenvironment for T-cell priming. However, intramuscular or subcutaneous delivery of vaccine to DCs, a subset of antigen-presenting cells, has failed to stimulate optimal immune response for effective vaccination and need for adjuvants to induce immune response. To address this issue, we developed an in situ-forming injectable hybrid hydrogel that spontaneously assemble into microporous network upon subcutaneous administration, which provide a cellular niche to host immune cells, including DCs. In situ-forming injectable hybrid hydrogelators, composed of protein-polymer conjugates, formed a hydrogel depot at the close proximity to the dermis, resulting in a rapid migration of immune cells to the hydrogel boundary and infiltration to the microporous network. The biocompatibility of the watery microporous network allows recruitment of DCs without a DC enhancement factor, which was significantly higher than that of traditional hydrogel releasing chemoattractants, granulocyte-macrophage colony-stimulating factor. Owing to the sustained degradation of microporous hydrogel network, DNA vaccine release can be sustained, and the recruitment of DCs and their homing to lymph node can be modulated. Furthermore, immunization of a vaccine encoding amyloid-β fusion proteinbearing microporous network induced a robust antigen-specific immune response in vivo and strong recall immune response was exhibited due to immunogenic memory. These hybrid hydrogels can be administered in a minimally invasive manner using hypodermic needle, bypassing the need for cytokine or DC enhancement factor and provide niche to host immune cells. These findings highlight the potential of hybrid hydrogels that may serve as a simple, yet multifunctional, platform for DNA vaccine delivery to modulate immune response.</P>

A 18-pJ/Pulse OOK CMOS Transmitter for Multiband UWB Impulse Radio

Tuan-Anh Phan,Jeongseon Lee,Krizhanovskii, V.,Seok-Kyun Han,Sang-Gug Lee THE INSTITUTE OF ELECTRICAL ENGINEERS 2007 Vol. No.

<P>This letter presents a new transmitter for multiband impulse radio ultra-wideband (IR-UWB) systems. The ultra low-power, low-complexity UWB transmitter operates over three 528-MHz subbands in 3-5 GHz band. It consists of an on-off keying (OOK) modulator and a pulse generator which is based on the ON/OFF switching operation of an LC oscillator. Measurements show a pulse duration of 3.5 ns and a spectrum that fully complies with the FCC spectral mask with more than 20 dB of sidelobe rejection. Implemented in 0.18-mum CMOS technology, the transmitter operates in burst mode and dissipates only 18 pJ of energy consumption per pulse. The transmitter is best suited for energy detection receivers.</P>

The neuroprotective effect of eupatilin against ischemia/reperfusion-induced delayed neuronal damage in mice

Cai, M.,Phan, P.T.T.,Hong, J.G.,Kim, D.H.,Kim, J.M.,Park, S.J.,Liu, X.,Han, J.E.,Park, H.,Choi, J.W.,Ryu, J.H. North-Holland ; Elsevier Science Ltd 2012 european journal of pharmacology Vol.689 No.1

Eupatilin, a pharmacologically active flavone derived from the Artemisia plant species, has been reported to have anti-oxidant, anti-inflammatory, anti-allergic, and anti-tumor activities. In the present study, we investigated whether eupatilin exhibits neuroprotective activities against ischemia/reperfusion-induced delayed neuronal injury in mice. Transient global cerebral ischemia was induced in mice by bilateral common carotid artery occlusion (BCCAO) for 15min followed by reperfusion for 4 days. Eupatilin (1, 3, or 10mg/kg, p.o.) was administered immediately after the reperfusion. Histochemical studies showed that eupatilin (10mg/kg) increased the number of viable cells detected by Nissl staining and decreased the number of degenerating neuronal cells detected by Fluoro-Jade B staining in the hippocampal CA1 region. Western blotting indicated that eupatilin further increased the level of Akt phosphorylation at 8h after BCCAO. Furthermore, wortmannin, a phosphatidylinositol 3-kinase inhibitor, attenuated the eupatilin-induced increase of Akt phosphorylation. In addition, wortmannin completely reversed the eupatilin-induced neuroprotective effects observed at 4 days after reperfusion. These findings suggest that eupatilin is a promising therapeutic agent against global cerebral ischemia-induced neuronal damage and that its neuroprotective effects may be mediated in part by increased Akt phosphorylation.