First-to-second-order magnetic-phase transformation in La_0.7Ca_0.3-xBa_xMnO₃ exhibiting large magnetocaloric effect

Phan, T.L.,Dang, N.T.,Ho, T.A.,Manh, T.V.,Thanh, T.D.,Jung, C.U.,Lee, B.W.,Le, A.T.,Phan, A.D.,Yu, S.C. Elsevier Sequoia 2016 Journal of alloys and compounds Vol.657 No.-

We have prepared polycrystalline samples La<SUB>0.7</SUB>Ca<SUB>0.3-x</SUB>Ba<SUB>x</SUB>MnO<SUB>3</SUB> (x = 0, 0.025, 0.05, 0.075 and 0.1) by solid-state reaction, and then studied their magnetic properties and magnetocaloric (MC) effect based on magnetization versus temperature and magnetic-field (M-H-T) measurements. Experimental results reveal the easiness in tuning the Curie temperature (T<SUB>C</SUB>) from 260 to about 300 K by increasing Ba-doping concentration (x) from 0 to 0.1. Under an applied field H = 50 kOe, maximum magnetic-entropy changes around T<SUB>C</SUB> of the samples can be tuned in the range between 6 and 11 J kg<SUP>-1</SUP> K<SUP>-1</SUP>, corresponding to refrigerant-capacity values ranging from 190 to 250 J kg<SUP>-1</SUP>. These values are comparable to those of some conventional MC materials, and reveal the applicability of La<SUB>0.7</SUB>Ca<SUB>0.3-x</SUB>Ba<SUB>x</SUB>MnO<SUB>3</SUB> materials in magnetic refrigeration. Analyses of the critical behavior based on the Banerjee criteria, Arrott plots and scaling hypothesis for M-H-T data prove a magnetic-phase separation when Ba-doping concentration changes. In the doping region x = 0.05-0.075, the samples exhibits the crossover of first- and second-order phase transitions with the values of critical exponents β and γ close to those expected for the tricritical mean-field theory. The samples with x < 0.05 and x > 0.075 exhibit first- and second-order transitions, respectively. More detailed analyses related to the Griffiths singularity, the critical behavior for different magnetic-field intervals started from 10 kOe, and the magnetic-ordering parameter n = dLn|ΔS<SUB>m</SUB>|/dLnH (where ΔS<SUB>m</SUB> is the magnetic-entropy change) demonstrate magnetic inhomogeneities and multicritical phenomena existing in the samples.

Magnetic and magnetocaloric properties in La_0.7Ca_0.3-xNa_xMnO₃ exhibiting first-order and second-order magnetic phase transitions

Ho, T.A.,Dang, N.T.,Phan, T.L.,Yang, D.S.,Lee, B.W.,Yu, S.C. Elsevier Sequoia 2016 JOURNAL OF ALLOYS AND COMPOUNDS Vol.676 No.-

Polycrystalline orthorhombic samples La<SUB>0.7</SUB>Ca<SUB>0.3-x</SUB>Na<SUB>x</SUB>MnO<SUB>3</SUB> (x = 0-0.09) were prepared by solid-state reaction. The study of magnetic properties revealed that the ferromagnetic-paramagnetic (FM-PM) transition temperature (T<SUB>C</SUB>) increases from 255 to about 271 K with increasing Na-doping content (x) from 0 to 0.09, respectively. Around the T<SUB>C</SUB>, we have found the samples showing a large magnetocaloric (MC) effect with maximum values of magnetic entropy change (|ΔS<SUB>max</SUB>|) of 7-8 J kg<SUP>-1</SUP> K<SUP>-1</SUP> and relative cooling power RCP = 232-236 J/kg for the samples x = 0.03-0.09 in a magnetic-field interval ΔH = 40 kOe. Detailed analyses of isothermal magnetization data M(T, H) based on Banerjee's criteria indicated a first-to-second-order magnetic-phase transformation taking place at a threshold Na-doping concentration x<SUB>c</SUB> ~ 0.06. This could also be observed clearly from the feature of entropy universal curves. An assessment of the magnetic-ordering exponent N = dLn|ΔS<SUB>m</SUB>|/dLnH demonstrates an existence of short-range magnetic order in the samples. We believe that the changes of the magnetic properties and MC effect in La<SUB>0.7</SUB>Ca<SUB>0.3-x</SUB>Na<SUB>x</SUB>MnO<SUB>3</SUB> caused by Na doping are related to the changes in the structural parameters and Mn<SUP>4+</SUP>/Mn<SUP>3+</SUP> ratio, which are confirmed by the geometrical and electronic analyses based on X-ray diffraction and X-ray absorption fine structure.

Magnetic and magnetocaloric properties of Ni-Ag-Mn-Sn ribbons and their composites

Thanh, Tran Dang,Duc, Nguyen Huu,Dan, Nguyen Huy,Mai, N.T.,Phan, T.L.,Oh, S.K.,Yu, Seong-Cho Elsevier 2017 Journal of Alloys and Compounds Vol.696 No.-

<P><B>Abstract</B></P> <P>In this work, we have investigated the influence of Ag-doping on the magnetic and magnetocaloric effect (MCE) of Ni<SUB>50-x</SUB>Ag<SUB>x</SUB>Mn<SUB>37</SUB>Sn<SUB>13</SUB> ribbons with <I>x</I> = 1, 2, and 4, which were prepared by a melt-spinning method. With increasing Ag concentration, a systematic decrease in the antiferromagnetic interaction and in the magnetic phase transition temperatures was observed. Analyses of the critical behavior based on the Banerjee criterion and scaling hypothesis for <I>M</I>(<I>H</I>, <I>T</I>) data near the ferromagnetic-paramagnetic transformation prove an increase of Ag favors establishing long-range ferromagnetic interactions in the austenitic phase. The temperature and magnetic field dependences of magnetic entropy change, Δ<I>S</I> <SUB>m</SUB>(<I>T</I>, <I>H</I>) were investigated via isothermal magnetization measurements. Interestingly, these samples exhibit a MCE at room-temperature with the Δ<I>S</I> <SUB>m</SUB>(<I>T</I>) curves distributed over a quite wide temperature range. To enhance the relative cooling power (RCP) value and to extend the magnetic phase transition region, we have prepared the composites in the form of the layered material samples based on ribbons obtained above. Under Δ<I>H</I> = 10 kOe, the maximum value of Δ<I>S</I> <SUB>m</SUB> (denoted as |Δ<I>S</I> <SUB>max</SUB>|) at around room-temperature is 1.08 J kg<SUP>−1</SUP> K<SUP>−1</SUP>, corresponding to RCP = 51.8 J kg<SUP>−1</SUP>, which is about 10% higher than that obtained from a separate sample. Additionally, we also pointed out that the dependences of |Δ<I>S</I> <SUB>max</SUB>| on Δ<I>H</I> at around room-temperature for samples obey a power law, |Δ<I>S</I> <SUB>max</SUB>| = <I>a</I> × Δ<I>H</I> <SUP>n</SUP>, and all the Δ<I>S</I> <SUB>m</SUB>(<I>T</I>, <I>H</I>) data obey completely a universal master curve.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An increase of Ag in Ni<SUB>1-x</SUB>Ag<SUB>x</SUB>Mn<SUB>37</SUB>Sn<SUB>13</SUB> ribbons favors establishing long-range FM order in the austenitic phase. </LI> <LI> High magnetic entropy change, wide operative temperature range, and high RCP value around room-temperature. </LI> <LI> The composite of Ni<SUB>1-x</SUB>Ag<SUB>x</SUB>Mn<SUB>37</SUB>Sn<SUB>13</SUB> ribbons exhibits higher RCP value and extends the magnetic phase transition region. </LI> <LI> Field dependence of |Δ<I>S</I> <SUB>max</SUB>| can be expressed by the power law. </LI> <LI> All the Δ<I>S</I> <SUB>m</SUB>(<I>T, H</I>) data around room temperature are followed a universal master curve. </LI> </UL> </P>

한우 종모우의 혈연관계 추적

김내수(N. S. Kim),이중재(J. J. Lee),당창권(C. G. Dang),정용호(Y. H. Jeoung),원유석(Y. S. Won) 충북대학교 동물생명과학연구소 2010 동물생명과학연구 Vol.3 No.-

The purpose of this study was to monitor the status of pedigree structure and to estimate the additive relationship and inbreeding coefficients of active Hanwoo proven bulls. A total 3,760 Pedigree records of proven and young bulls and heifers from 1983 to 2008 were used in this study. Intel Visual Fortran Compiler (Window Ver. 11.1) was used to compute the numerator relationship matrix(A) and to estimate the inbreeding coefficients using the self-made fortran program included three subroutines(MATCH, SHIFT, NRM). The ratio of relatedness among the active Hanwoo proven bulls ranged from 20.75 to 94.34% and the inbreeding coefficients of 4 proven bulls were estimated 0.78, 3.13, 0.05 and 1.56%, respectively. The estimated inbreeding coefficients were less than other researches. However, the ratio of relatedness among the active Hanwoo proven bulls was estimated very high. Because of these results, the probability of inbred animals will be increased. Therefore, cattle breeders will be considered the active selection index consisting of economic weight as well as relationship and inbreeding coefficients of animals when the proven bulls will be selected.

Ferromagnetism-to-Paramagnetism Transition in the ZnMnO System

V. S. Dang,Y. Y. Song,N. Q. Hoa,유성초,Y. G. Yoo 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

The magnetic properties of Mn- and P-doped ZnO prepared by using the solid state reaction and pulsed laser deposition (PLD) were investigated by measuring the magnetization and the absorption derivative of the electron paramagnetic resonance (EPR). The film's thickness was about 0.3 μm. The X-ray diraction pattern indicated a single-phase polycrystalline ZnO structure without any MnO₂ phase in both the polycrystalline samples and the thin lms. The magnetic behaviors of the samples were determined by using an alternating gradient magnetometer (AGM) at room tempera- ture. All the bulk samples showed ferromagnetism at room temperature. Mn-doped ZnO films with Zn₃P₂ added also showed ferromagnetism at room temperature. A transition from ferromagnetism to paramagnetism with increasing in sintering temperature was detected in the EPR experiments. The absorption derivative of the EPR signal showed hyperne splitting for the samples sintered at 800 and 900℃ due to a spin degeneracy of Mn²+, the hyperfine splitting disappeared for the samples sintered at 1000℃ due to a superposition of the six lines of hyperfine splitting.

Ferromagnetic Resonance of Soft Magnetic CoFeAlO Thin Films

V. S. Dang,T.L. Phan,N.D. Ha,C.O.Kim,S.C. Yu 한국자기학회 2007 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

Magnetic and magnetocaloric properties of Sm_1−xCa_xMnO₃ (<i>x</i> =0.88) nanoparticles

Phan, T.L.,Dang, N.T.,Ho, T.A.,Rhyee, J.S.,Shon, W.H.,Tarigan, K.,Manh, T.V. North-Holland Pub. Co 2017 Journal of magnetism and magnetic materials Vol.443 No.-

<P><B>Abstract</B></P> <P>We used the mechanical milling to prepare orthorhombic Sm<SUB>0.12</SUB>Ca<SUB>0.88</SUB>MnO<SUB>3</SUB> samples with the average crystallite size (<I>d</I>) changing from 100 to 139nm. Their magnetic and magnetocaloric properties were then studied upon magnetization data versus the temperature and magnetic field, <I>M</I>(<I>T</I>, <I>H</I>). The results revealed the samples undergoing the ferromagnetic-paramagnetic (FM-PM) phase transition at the Curie temperature <I>T</I> <SUB>C</SUB> ≈110K. Around this transition, the magnetic-entropy change (Δ<I>S</I> <SUB>m</SUB>) reaches the maxima. The maximum |Δ<I>S</I> <SUB>m</SUB>| values are about 2–4J·kg<SUP>−1</SUP>·K<SUP>−1</SUP>, corresponding to relative cooling power of 35–60J·kg<SUP>−1</SUP>, for an applied field <I>H</I> =30kOe. The assessments based on Banerjee’s criteria and constructing a universal curve for |Δ<I>S</I> <SUB>m</SUB>(<I>T</I>, <I>H</I>)| data indicate the samples having the nature of a second-order phase transition. Also, the detailed analyses based on the Curie-Weiss law and magnetic-order exponent prove the existence of the Griffiths phase and magnetic inhomogeneity in the samples. These properties would be changed by changing <I>d</I>.</P>

Tricritical behavior and Griffith phase in La_1-xCa_xMnO₃ under high applied fields

Phan, T.L.,Tola, P.S.,Dang, N.T.,Rhyee, J.S.,Shon, W.H.,Ho, T.A. Elsevier 2017 Journal of magnetism and magnetic materials Vol.441 No.-

<P><B>Abstract</B></P> <P>Studying the magnetic property of La<SUB>0.7</SUB>Ca<SUB>0.3</SUB>MnO<SUB>3</SUB> (LCMO) bulks, it has been found that they exhibit a first-order phase transition (FOPT) around the ferromagnetic-paramagnetic (FM-PM) transition. However, most previous studies just concerned on their magnetic property for applied fields below 60kOe. To learn more about this material system, we have considered the influence of high applied fields up to 140kOe on the magnetic property of a polycrystalline LCMO bulk sample. The detailed analyses based on the Banerjee criterion, Arrott and Kouvel-Fisher methods, and scaling hypothesis prove LCMO exhibiting the first-order phase transition at low applied fields (<I>H</I>) and the tricritical behavior at high applied fields <I>H</I> >65kOe with critical exponents <I>β</I> ≈0.25 and <I>γ</I> ≈1 close to those expected for the tricritical mean-field theory. We have also found a strong dependence of the FM-PM transition temperature (<I>T</I> <SUB>C</SUB>) on <I>H</I> varying as a power function <I>T</I> <SUB>C</SUB>(<I>H</I>)∝ <I>H<SUP>n</SUP> </I> (with <I>n</I> =0.64 and <I>H</I> >3.5kOe), and an existence of the Griffiths phase that is completely suppressed as <I>H</I> ≥35kOe.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High applied fields influence the magnetic properties of La<SUB>0.7</SUB>Ca<SUB>0.3</SUB>MnO<SUB>3</SUB>. </LI> <LI> Transformation from the first order to the crossover of first- and second-order transitions. </LI> <LI> The suppression of Griffiths phase. </LI> </UL> </P>

Study on the Design of Underwater Chain Trencher

N. L. D. Hai(Nguyen Le Dang Hai),J. Kim,O S. Kwon,J. H. Ko 유공압건설기계학회 2019 유공압건설기계학회 학술대회논문집 Vol.2019 No.6

In this study, a design process for an underwater trencher is introduced. Design optimization based on genetic algorithm is applied to obtain an optimal design and then chain-sprocket selection is followed. The prototype is fabricated based on the design process and is successfully demonstrated.

Evaluation and treatment of facial feminization surgery: part I. forehead, orbits, eyebrows, eyes, and nose

Dang, Brian N.,Hu, Allison C.,Bertrand, Anthony A.,Chan, Candace H.,Jain, Nirbhay S.,Pfaff, Miles J.,Lee, James C.,Lee, Justine C. Korean Society of Plastic and Reconstructive Surge 2021 Archives of Plastic Surgery Vol.48 No.5

Facial feminization surgery (FFS) incorporates aesthetic and craniofacial surgical principles and techniques to feminize masculine facial features and facilitate gender transitioning. A detailed understanding of the defining male and female facial characteristics is essential for success. In this first part of a two-part series, we discuss key aspects of the general preoperative consultation that should be considered when evaluating the prospective facial feminization patient. Assessment of the forehead, orbits, hairline, eyebrows, eyes, and nose and the associated procedures, including scalp advancement, supraorbital rim reduction, setback of the anterior table of the frontal sinus, rhinoplasty, and soft tissue modifications of the upper and midface are discussed. In the second part of this series, bony manipulation of the midface, mandible, and chin, as well as soft tissue modification of the nasolabial complex and chondrolaryngoplasty are discussed. Finally, a review of the literature on patient-reported outcomes in this population following FFS is provided.