Epitaxial Multiferroic BiFeO3 Thin Films: Progress and Future Directions

Chu, Y. H.,Martin, L. W.,Zhan, Q.,Yang, P. L.,Cruz, M. P.,Lee, K.,Barry, M.,Yang, S. Y.,Ramesh, R. Taylor Francis 2007 Ferroelectrics Vol.354 No.1

<P> We write this article in honor of Professor Vitaly L. Ginzburg, truly the father of the field of ferroelectricity. This article serves as a review of the current state of research pertaining to multiferroic BiFeO3 thin films. In this review we will delve into details of the growth of BiFeO3 thin films and the use of piezoforce microscopy and x-ray reciprocal space mapping to characterize the crystal structure and domain structure of BiFeO3. We will also discuss the use of vicinal and asymmetric substrates to simplify the domain structure in BiFeO3. By simplifying the domain structure we can, in turn, control the ferroelectric switching mechanisms in BiFeO3. Finally we describe the basic ferroelectric properties of BFO films and discuss the critical issues needed to be solved in BiFeO3 films including leakage, complex domain structure, coercivity, and reliability. Such results are promising for continued exploration for detailed multiferroic-coupling studies in the magnetoelectric BiFeO3 system and BiFeO3, in turn, provides a model platform with which to realize the exciting possibility of electrically control magnetism.</P>

Cross-Coupled Narrow-Band YBCO Filters with Spurious Suppression by Using a Tap-Connection Technique

L. M. Wang,Chung-I G. Hsu,D. S. Hsieh,L. H. Chen,M. L. Chu,S. M. Chiou 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.5I

Narrow-band microstrip cross-coupled band-pass filters based on a quadruplet geometry were designed for wireless-communication applications. High-Tc superconducting (HTS) filters were fabricated by patterning YBa2Cu3Oy (YBCO) films double-side deposited on 20-mm-square and 0.5- mm-thick LaAlO3 substrates. The filters with skew-symmetric feed were designed with a center frequency at 1.9 GHz and a bandwidth of 20 MHz. The inductive coupling between the non-adjacent resonators produced a pair of transmission zeros in the frequency response. Also observed was an additional pair of transmission zeros that enhance the out-of-band rejection characteristics. The realized YBCO filter showed a center frequency at 1.925 GHz with a bandwidth of 20 MHz and a minimum insertion loss of about 0.74 dB. Furthermore, a tap-connection technique was applied to cross-coupled HTS band-pass filters so as to suppress the second and/or the third passbands, which were spurious and undesirable. To improve the out-of-band performance of the band-pass filters, we tapped the input/output microstrip lines at certain locations. In this research, we confirmed that by tapping somewhere along the input/output microstrip lines, a /4 open stub or a /2 short stub, where refers to the guided wavelength at 2fo or 3fo, may effectively suppress harmonics at 2fo and/or 3fo by more than 25 dB. The simulated and the experimental results are discussed.

Association between Melatonin Receptor 1A Gene and Expression of Reproductive Seasonality in Sheep

Chu, M.X.,Cheng, D.X.,Liu, W.Z.,Fang, L.,Ye, S.C. Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.8

To determine whether a link exists between reproductive seasonality and the structure of the melatonin receptor 1A (MTNR1A) gene, the latter was studied in nonseasonal estrous breeds (Small Tail Han and Hu ewes) and seasonal estrous breeds (Dorset, Suffolk and German Mutton Merino ewes). A large fragment of the exon 2 of the MTNR1A gene was amplified and a uniform fragment of 824 bp was obtained in 239 ewes of five breeds. The 824 bp PCR product was digested with restriction endonucleases Mnl I and Rsa I, and checked for the presence of restriction sites. The presence (allele M) or absence (allele m) of an Mnl I site at base position 605 led to three genotypes MM (236 bp/236 bp), Mm (236 bp/303 bp) and mm (303 bp/303 bp) in five sheep breeds. The presence (allele R) or absence (allele r) of a Rsa I site at base position 604 led to three genotypes RR (267 bp/267 bp), Rr (267 bp/290 bp) and rr (290 bp/290 bp) in five sheep breeds. Frequencies of MM and RR genotypes were obviously higher, and frequencies of mm and rr genotypes were obviously lower in nonseasonal estrous sheep breeds than in seasonal estrous sheep breeds. Sequencing revealed four mutations (G453T, G612A, G706A, C891T) in mm genotype compared to MM genotype and one mutation (C606T) in rr genotype compared to RR genotype. For polymorphic Mnl I and Rsa I cleavage sites, the differences of genotype distributions were very highly significant (p<0.01) between Small Tail Han ewes and seasonal estrous sheep breeds. In each group, no significant difference (p>0.05) was detected. These results preliminarily showed an association between MM, RR genotypes and nonseasonal estrus in ewes and an association between mm, rr genotypes and seasonal estrus in ewes.

GaAs Heterojunction Bipolar Transistor (HBT) Technology for 0.8-6 GHz Commercial Wireless Communications

Kim, M. E.,Gorman, G. M.,Cho, N. M.,Kong, K. S.,Champaneria, C. N.,Greene, J. E.,Bruckner, C. L.,Walsworth, C. R.,Do, V. A.,Coleman, D. W.,Hew, P. R.,Chung, S. C.,Jung, W.,Seo, H. C.,Hwang, Y. I.,Chu, 대한전자공학회 1993 ICVC : International Conference on VLSI and CAD Vol.3 No.1

This paper .discusses the GaAs HBT device and IC technology and its application to commercial wireless communication systems in the 0.8-6 GHz frequency range. Key performance/cost advantages of the GaAs HBT previously established over silicon bipolar and GaAs MESFET in this frequency regime are now being applied to critical RF front-end requirements of wireless voice and data communication systems. GaAs HBT components developed far such wireless systems include small-signal .and power functions which offer combinations of higher gain-bandwidth, higher efficiency, lower distortion, wider dynamic range and simpler design implementations. GaAs HBT/IC fabrication technology, device/IC performance and system applications are discussed.

MEDICAL MYCOLOGY & OTHERS : CLINICAL USE OF ITRACONAZOLE ( SPORANOX , R51211 ) IN ONYCHOMYCOSES

( T . M . Jen,C . D . Tsai,Y . L . Chien,M . L . Tseng,E . M . Lee,M . T . Liu,Y . T . Chang,C . F . Chu,W . L . Jen,D . D . Lee,J . J . Shiue,Y . L . Huang ) 한국균학회 1992 MYCOLOGICAL SYMPOSIUM Vol.- No.-

Stability Analysis of the KSTAR PF Busline

Park, Y. M.,Lee, H. J.,Chu, Y.,Park, D. S.,Kwag, S. W.,Song, N. H.,Woo, I. S.,Chang, Y. B.,Joo, J. J.,Moon, K. M.,Kim, S. H.,Park, K. R.,Yang, H. L.,Kwon, M. IEEE 2012 IEEE transactions on applied superconductivity Vol.22 No.3

<P>The Cable-In-Conduit Conductor (CICC) for the KSTAR buslines is made of NbTi superconducting (SC) strands. A busline consists of several electrical joints, which are the major heat load contributors to the busline cryo-system. In the poloidal field (PF) busline helium circuit, the supercritical helium is fed to the electrical joint of current lead end and comes out to the magnet terminal joint. This helium flow configuration has been verified to maintain the cryogenic stability of the buslines through the KSTAR operation. During the normal operation of the KSTAR PF coil, the heated helium coming out to both the coil and the busline meets at the magnet terminal and exchange heat, but the busline outlet temperature still remained less than magnet outlet temperature. As the buslines for the electrical connection in series of the upper and lower coils for PF1 and PF2 have the helium path through the two terminal joints of magnet, they experience higher temperature than the other buslines mainly due to the larger heat exchange. In this case, the connection buslines are considered to have very low safety margin and have the strong possibility of quenches.</P>

Electric modulation of conduction in multiferroic Ca-doped BiFeO₃ films

Yang, C.-H.,Seidel, J.,Kim, S. Y.,Rossen, P. B.,Yu, P.,Gajek, M.,Chu, Y. H.,Martin, L. W.,Holcomb, M. B.,He, Q.,Maksymovych, P.,Balke, N.,Kalinin, S. V.,Baddorf, A. P.,Basu, S. R.,Scullin, M. L.,Rames Nature Publishing Group 2009 Nature materials Vol.8 No.6

Many interesting materials phenomena such as the emergence of high-Tc superconductivity in the cuprates and colossal magnetoresistance in the manganites arise out of a doping-driven competition between energetically similar ground states. Doped multiferroics present a tantalizing evolution of this generic concept of phase competition. Here, we present the observation of an electronic conductor–insulator transition by control of band-filling in the model antiferromagnetic ferroelectric BiFeO<SUB>3</SUB> through Ca doping. Application of electric field enables us to control and manipulate this electronic transition to the extent that a p–n junction can be created, erased and inverted in this material. A ‘dome-like’ feature in the doping dependence of the ferroelectric transition is observed around a Ca concentration of ∼1/8, where a new pseudo-tetragonal phase appears and the electric modulation of conduction is optimized. Possible mechanisms for the observed effects are discussed on the basis of the interplay of ionic and electronic conduction. This observation opens the door to merging magnetoelectrics and magnetoelectronics at room temperature by combining electronic conduction with electric and magnetic degrees of freedom already present in the multiferroic BiFeO<SUB>3</SUB>.

Association Analysis between Five Microsatellite Loci and Litter Size in Small Tail Han Sheep

Chu, M.X.,Wang, J.Z.,Wang, A.G.,Li, N.,Fu, J.L. Asian Australasian Association of Animal Productio 2003 Animal Bioscience Vol.16 No.11

The objective of the present study was to explore associations between five microsatellites linked to $Fec^B$ and $FecX^I$ genes and litter size in Small Tail Han sheep. The polymorphisms of five microsatellite loci, OarAE101, BM1329, BMS2508, TGLA54 and TGLA68 were detected in 244 ewes of Small Tail Han sheep. Analysis of association between three microsatellite loci (BMS2508, BM1329 and OarAE101) located in the 10 cM region covering the $Fec^B$ gene (Booroola gene) and litter size in Small Tail Han sheep indicated that BMS2508 had significant effect on litter size in the second parity (p<0.05), but no significant effect on litter size in the first parity (p>0.05), while the other two microsatellite loci had no significant effect on litter size in both the first and the second parity in Small Tail Han sheep (p>0.05). At microsatellite locus BMS2508, least squares means in the second parity of genotypes 101/111 and 99/109 were significantly higher than those of genotypes 99/99, 99/101, 99/111 and 99/115 (p<0.05); least squares mean in the second parity of genotype 101/111 was significantly higher than that of genotypes 109/111 and 111/111 (p<0.05). Results of this study also indicated that two microsatellite loci (TGLA54 and TGLA68) that confined the 28.7 cM region covering the $FecX^I$ gene (Inverdale gene) did not affect litter size in both the first and the second parity in Small Tail Han sheep significantly (p>0.05). The information found in the present study is very important for improving the reproductive performance in sheep breeds by marker assisted selection.

Association between PCR-RFLP of Melatonin Receptor 1a Gene and High Prolificacy in Small Tail Han Sheep

Chu, M.X.,Ji, C.L.,Chen, G.H. Asian Australasian Association of Animal Productio 2003 Animal Bioscience Vol.16 No.12

Melatonin regulates circadian rhythms and reproduction changes in seasonally reproductive mammals through binding to high-affinity, G-protein-coupled receptors. Small Tail Han sheep that has significant characteristics of high prolificacy and nonseasonal ovulatory activity is an excellent local sheep breed in P. R. China. The exon 2 of the ovine melatonin receptor 1a (MTNR1A) gene was amplified and a uniform fragment of 824 bp was obtained in 150 ewes of Small Tail Han sheep. The 824 bp PCR product was digested with restriction endonucleases Mnl I and Rsa I, and genetic polymorphism was detected by PCR-RFLP. Polymorphic Mnl I site was detected at base position 605 of the exon 2 of the MTNR1A gene. There were two kinds of genotypes in Small Tail Han sheep, AB (303 bp, 236 bp/67 bp) and BB (236 bp/67 bp, 236 bp/67 bp). The results indicated that genotype AA (303 bp, 303 bp) at Mnl I-RFLP site did not exist in non-seasonal estrous Small Tail Han sheep, which suggested that there was an association between genotype AA (303 bp, 303 bp) and reproductive seasonality in sheep. Polymorphic Rsa I site was detected at base position 604 of the exon 2 of the MTNR1A gene. Three kinds of genotypes were found in Small Tail Han sheep, AA (290 bp, 290 bp), AB (290 bp, 267 bp/23 bp) and BB (267 bp/23 bp, 267 bp/23 bp). Least squares means of litter size in the first parity and the second parity for genotype AA (290 bp, 290 bp) at Rsa I-RFLP site were 0.43 and 1.06 more than those for genotype AB (290 bp, 267 bp/23 bp) in Small Tail Han sheep.

PCR-SSCP Polymorphism of Inhibin ${\beta}_A$ Gene in Some Sheep Breeds

Chu, M.X.,Xiao, C.T.,Fu, Y.,Fang, L.,Ye, S.C. Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.7

Inhibins participate in the regulation of pituitary follicle-stimulating hormone synthesis and secretion, follicular maturation and steroidogenesis in the female. Inhibin ${\beta}_A$ gene (INHBA) was studied as a candidate gene for the prolificacy of sheep. Single nucleotide polymorphisms of the entire coding region and partial 3' untranslated region of INHBA were detected by PCR-SSCP in two high fecundity breeds (Small Tail Han and Hu sheep) and six low fecundity breeds (Dorset, Texel, German Mutton Merino, South African Mutton Merino, Chinese Merino and Corriedale sheep). Only the PCR products amplified by primers 3, 4 and 5 displayed polymorphisms. For primer 3, genotype CC was only detected in Chinese Merino sheep, genotype AA was detected in the other seven sheep breeds. Genotype BB was only detected in Hu sheep. Only Hu sheep displayed polymorphism. Eight or four nucleotide mutations were revealed between BB or CC and AA, respectively, and these mutations did not result in any amino acid change. For primer 4, genotypes EE, EG and GG were detected in Dorset and German Mutton Merino sheep, genotypes EE, EF and FF were detected in Chinese Merino sheep, only genotype EE was detected in the other five sheep breeds. Only Dorset, German Mutton Merino and Chinese Merino sheep displayed polymorphism. Sequencing revealed one nucleotide mutation ($114G{\rightarrow}A$) of exon 2 of INHBA gene between genotype FF and genotype EE, and this mutation did not cause any amino acid change. Another nucleotide change ($143C{\rightarrow}T$) was identified between genotype GG and genotype EE, and this mutation resulted in an amino acid change of $serine{\rightarrow}leucine$. For primer 5, genotypes KK and KL were detected in German Mutton Merino and Corriedale sheep, genotypes KK, LL and KL were detected in the other six sheep breeds. Genotype MM was only detected in Hu sheep. All of these eight sheep breeds displayed polymorphism. Sequencing revealed one nucleotide mutation ($218A{\rightarrow}G$) of exon 2 of the INHBA gene between genotype LL and genotype KK, and nine nucleotide mutations between genotype MM and genotype KK. These mutations did not alter amino acid sequence. The partial sequence (395 bp for exon 1 and 933 bp for exon 2) of the INHBA gene in Small Tail Han sheep (with genotype KK for primer 5) was submitted into GenBank (accession number EF192431). Small Tail Han sheep displayed polymorphisms only in the fragment amplified by primer 5. The Small Tail Han ewes with genotype LL had 0.53 (p<0.05) or 0.63 (p<0.05) more lambs than those with genotype KL or KK, respectively. The Small Tail Han ewes with genotype KL had 0.10 (p>0.05) more lambs than those with genotype KK.