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Lim, Sung-Ji,Nam, Gnu,Shin, Seungeun,Ahn, Kyunghan,Lee, Yunho,You, Tae-Soo ACS AMERICAN CHEMICAL SOCIETY 2019 Inorganic Chemistry Vol.58 No.9
<P>Three Zintl phase compounds belonging to the CaYb<SUB>4</SUB>Al<SUB>2</SUB>Sb<SUB>6-<I>x</I></SUB>Ge<SUB><I>x</I></SUB> (<I>x</I> = 0.2, 0.5, 0.7; nominal compositions) system with various Ge-doping contents were successfully synthesized by arc-melting and were initially crystallized in the Ba<SUB>5</SUB>Al<SUB>2</SUB>Bi<SUB>6</SUB>-type phase (space group <I>Pbam</I>, Pearson codes <I>oP</I>26). However, after post-heat treatment at an elevated temperature, the originally obtained crystal structure was transformed into the homeotypic Ca<SUB>5</SUB>Ga<SUB>2</SUB>Sb<SUB>6</SUB>-type structure according to powder and single-crystal X-ray diffraction analyses. Two types of crystal structures share some isotypic structural moieties, such as the one-dimensional anionic chains formed by <SUB>∞</SUB><SUP>1</SUP>[Al<SUB>2</SUB>Sb<SUB>8</SUB>] and the void-filling Ca<SUP>2+</SUP>/Yb<SUP>2+</SUP> mixed cations, but the slightly different spatial arrangements in each unit cell make these two structural types distinguishable. This series of title compounds is originally investigated to examine whether anionic <I>p</I>-type doping using Ge can successfully enhance thermoelectric (TE) properties of the Yb-rich CaYb<SUB>4</SUB>Al<SUB>2</SUB>Sb<SUB>6-<I>x</I></SUB>Ge<SUB><I>x</I></SUB> series even after the phase transition from the Ba<SUB>5</SUB>Al<SUB>2</SUB>Bi<SUB>6</SUB>-type to the Ca<SUB>5</SUB>Ga<SUB>2</SUB>Sb<SUB>6</SUB>-type phase. More interestingly, we also reveal that the given structural transformation is triggered by the particularly different site-preference of Ca<SUP>2+</SUP> and Yb<SUP>2+</SUP> among three available cationic sites in each structure type, which is significantly affected by thermodynamic conditions of this system. Band structure and density of states analyses calculated by density functional theory using the tight-binding linear muffin-tin orbital method also prove that the Ge-doping actually increases band degeneracies and the number of resonant peaks near the Fermi level resulting in the improvement of Seebeck coefficients. Electron localization function analyses for the (0 1 0) sliced-plane and the 3D isosurface nicely illustrates the distortion of the paired-electron densities due to the introduction of Ge. The systematic TE property measurements imply that the attempted anionic <I>p</I>-type doping is indeed effective to improve the TE characteristics of the title CaYb<SUB>4</SUB>Al<SUB>2</SUB>Sb<SUB>6-<I>y</I></SUB>Ge<SUB><I>y</I></SUB> system.</P><P>The anionic <I>p</I>-type Ge doping and the particular cationic site-preference of Ca<SUP>2+</SUP> and Yb<SUP>2+</SUP> in the Yb-rich Zintl phase CaYb<SUB>4</SUB>Al<SUB>2</SUB>Sb<SUB>6−<I>x</I></SUB>Ge<SUB><I>x</I></SUB> (<I>x</I> = 0.2, 0.5, 0.7) system are proven to be the origin of the enhanced Seebeck coefficients and the observed structural transformation from the Ba<SUB>5</SUB>Al<SUB>2</SUB>Bi<SUB>6</SUB>-type to the Ca<SUB>5</SUB>Ga<SUB>2</SUB>Sb<SUB>6</SUB>-type phase.</P> [FIG OMISSION]</BR>
Aatif Ali Shah,Young Hoon Cho,SeungEun Nam,Ahrumi Park,You-In Park,Hosik Park 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.86 No.-
In this study, PVDF electrospun nanofibers impregnated with bentonite nanoclay based highlyhydrophilic thin-film nanocomposite (TFN) membranes were synthesized by interfacial polymerizationof a polyamide selective layer for forward osmosis (FO) applications. It was revealed that the bentonitenanoclay can tune the properties of the PVDF nanofiber supported TFN membranes, including the keyparameters, such as hydrophilicity, the β-phase fraction (polar phase), and its mechanical properties. ThePVDF/bentonite nanoclay mixture resulted in a significant improvement in FO performance. X-rayphotoelectron spectroscopy (XPS) and energy dispersive X-ray (EDX) analysis confirmed the successfulintegration of bentonite nanoclay into the electrospun nanofiber. The prepared TFN membranes showedhigher hydrophilicity, mechanical strength and water permeability compared to the pristine PVDFelectrospun nanofiber TFN membrane due to an increase in the β-phase fraction (hydrophilicity) by thesynergetic effect of electrospinning and addition of bentonite nanoclay. A TFN membrane with thehighest nanoclay content (2.0 wt%) showed an exceptionally high FO waterflux of 40.64 L/m2 h at 1 MNaCl draw solution, without a considerable increase in reverse soluteflux (RSF).
Ko Min-Jung,Chae Sang-Yeup,Lee Seungeun,Lee Dongmin,Song Jaeho,Park Jinkyung,Kim Jung-Hyun,Goo Bonhyuk,Park Yeon-Cheol,Seo Byung-Kwan,Baek Yong-Hyeon,Nam Sang-Soo 대한침구의학회 2023 대한침구의학회지 Vol.40 No.3
Background: The incidence of facial palsy has been increasing. Many patients consult both Korean and Western physicians; however, no critical pathway (CP) for facial palsy has been established based on integrated medicine including Korean medicine, Western medicine, and complementary and alternative medicine. Thus, we developed and implemented an integrated CP for patients with acute facial palsy and investigated the satisfaction with CP. Methods: Overall, 20 patients who received treatment following the CP and 20 medical staff members involved in their care responded to a questionnaire survey. The questionnaire was developed based on a review of previous studies and focused on the satisfaction with the CP. Results: Patients’ satisfaction score with the integrated CP was ≥ 4.4 for all items using a 5-point Likert-type scale. Smooth and cooperative treatment procedures, time-saving practices, and a clear explanation of the integrated treatment plan were satisfactory factors. Additionally, they preferred incorporating specialized facial massage and receiving education on self-exercise or massage techniques as complementary therapies. The medical staff members expressed a high level of satisfaction with the CP; however, the work division and treatment guidelines must be improved. Conclusion: An integrated CP program for acute facial palsy was implemented, and the satisfaction levels of patients and medical staff members were assessed. The results revealed high levels of satisfaction, and several improvements identified will be incorporated into clinical practice going forward.
Shivshankar Chaudhari,YongSung Kwon,MinYoung Shon,SeungEun Nam,You-In Park 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.81 No.-
Conventional distillation failed to separate a ternary azeotropic mixture of ECH, IPA and water (50/30/20 w/w, %) exist in the epoxy resin manufacturing process. Thus, we prepared a PVA-tetraethylorthosilicate organic–inorganic hybrid membrane and modified the membrane by layer-by-layerdeposition of a PVAm/silicotungstic acid polyelectrolyte for the pervaporation (PV) dehydration of ECH/IPA/water mixtures. In PV experiments at 30 C, theflux decreased from 0.14 to 0.05 kg m 2 h 1 andseparation factor increased from and 2099 to 13,320 with TEOS addition in the PVA membrane wasobserved. And for the layer by layer deposition on PVA-TEOS (4) membranesflux increased andseparation factor decreased from 0.14 to 0.28 kg m 2 h 1 and 2099 to 416 with the number of layer ofdeposition were observed respectively. On varying the feed water content from 20 to 10 wt. %, thepervaporationflux at 30 C decreased from 0.22 to 0.0066 kg m 2 h 1 and the separation factor increasedfrom 1061 to 9094 was observed. By applying the Arrhenius equation, permeation activation energies ofECH and IPA (97.42 and 111.96 kJ mol-1, respectively) are higher than that of water (40.88 kJ mol 1) werereported for the layer by layer membrane.
Shivshankar Chaudhari,YongSung Kwon,ChiYoung Park,MyungJun Moon,MinYoung Shon,SeungEun Nam,YouIn Park 한국막학회 2017 한국막학회 총회 및 학술발표회 Vol.2017 No.11
Blended membranes of hydrophilic polymers poly (vinyl alcohol) (PVA) and poly(vinyl amine) (PVAm) were prepared and crosslinked with glutaraldehyde. The characterization of membranes were done by using FTIR, XRD, DSC, SEM and swelling study. MB1.5 membrane was the best one in all since it exhibited higher separation index. By using blend membrane (MB1.5), the flux through a 65-mm film increased from 0.01 to 0.47 kg/m2h at an acetonitrile/water feed ratio between 20/80 and 5/95 w/w at 30°C while separation factor increased from the 5055 to 100.84 attributed to the higher hydrophilicity of blend membranes. On comparison of pervaporation data with water-acetonitrile vapor-liquid equilibrium data it was observed that the membrane acted as third phase to effectively break the azeotropes.
PVA based mixed matrix membrane for Isopropanol dehydration using Pervaporation assembly
Shivshankar Chaudhari,YongSung Kwon,ChiYoung Park,MyungJun Moon,MinYoung Shon,SeungEun Nam,YouIn Park 한국막학회 2017 한국막학회 총회 및 학술발표회 Vol.2017 No.11
The modification of Silicotungstic acid (STA) was done by Melamine and Mixed matrix membranes from the Melamine modified Silico tungstic acid (M-STA) particles were prepared for the pervaporation dehydration of Water -Isopropanol (IPA) mixture. The characterization of the membranes were done by FTIR, SEM, EDS AFM XRD, and contact angle measurements. The M-STA loaded composite membranes showed improved pervaporation performance in comparison to the virgin membrane. The 8 wt% M-STA loaded (M8-MSTA) membrane gave an optimum pervaporation performance having flux = 0.36 kg/m2h, separation factor 485.6 for 20 wt% water -isopropanol feed composition at 60 0C was observed.