Study on the Ventilation Method to Maintain the PM10 Concentration in a Subway Cabin below 35 μg/m3

The city of Seoul will limit the maximum particulate matter (PM₁₀) concentration to ≤35 μg/m³ (from 2024). Herein, a numerical parametric study was conducted on the PM removal efficiency of the heating, ventilation, and air conditioning (HVAC) filters installed in the ceiling of subway cabins. The PM₁₀ concentration distribution was explored according to the flow rate and flow rate ratio of the air introduced into the cabin. Under the current ventilation conditions of the subway train HVAC system, the PM₁₀ concentration was highest in the cabin central area where exhaust outlets are located and decreased toward both ends of the cabin. The indoor airflow was improved and the PM₁₀ concentration was reduced by increasing the flow rate of the supplied air at both ends of the cabin while decreasing it in the central area. It was found that the strengthened PM₁₀ concentration criterion of Seoul can be met by increasing the ventilation flow rate to 700 CMH (currently, 500 CMH) and the filter efficiency to 85% (currently, 70%) while maintaining the current flow rate ratio. These results are expected to be used as important reference data for reducing the PM concentration in subway cabins and thereby improving indoor air quality.

Survival of itinerant excitations and quantum spin state transitions in YbMgGaO4 with chemical disorder

A recent focus of quantum spin liquid (QSL) studies is how disorder/randomness in a QSL candidate affects its true magnetic ground state. The ultimate question is whether the QSL survives disorder or the disorder leads to a “spin-liquid-like” state, such as the proposed random-singlet (RS) state. Since disorder is a standard feature of most QSL candidates, this question represents a major challenge for QSL candidates. YbMgGaO₄, a triangular lattice antiferromagnet with effective spin-1/2 Yb³⁺ions, is an ideal system to address this question, since it shows no long-range magnetic ordering with Mg/Ga site disorder. Despite the intensive study, it remains unresolved as to whether YbMgGaO₄ is a QSL or in the RS state. Here, through ultralow-temperature thermal conductivity and magnetic torque measurements, plus specific heat and DC magnetization data, we observed a residual κ₀/T term and series of quantum spin state transitions in the zero temperature limit for YbMgGaO₄. These observations strongly suggest that a QSL state with itinerant excitations and quantum spin fluctuations survives disorder in YbMgGaO₄.

It remains an open question as to whether the quantum spin liquid state survives material disorder, or is replaced by some spin-liquid like state. Here, Rao et al succeed in resolving a resolving a κ₀/T residual in the thermal conductivity of YbMgGaO₄ strongly suggesting the survival of the quantum spin liquid state.

Magnetic ordering in the Ising antiferromagnetic pyrochlore Nd2ScNbO7

The question of structural disorder and its effects on magnetism is relevant to a number of spin liquid candidate materials. Although commonly thought of as a route to spin glass behaviour, here we describe a system in which the structural disorder results in long-range antiferromagnetic order due to local symmetry breaking. Nd₂ScNbO₇is shown to have a dispersionless gapped excitation observed in other neodymium pyrochlores belowT_N= 0.37 K through polarized and inelastic neutron scattering. However the dispersing spin waves are not observed. This excited mode is shown to occur in only 14(2)% of the neodymium ions through spectroscopy and is consistent with total scattering measurements as well as the magnitude of the dynamic moment 0.26(2)μ_B. The remaining magnetic species order completely into the all-in all-out Ising antiferromagnetic structure. This can be seen as a result of local symmetry breaking due disordered Sc⁺³and Nb⁺⁵ions about theA-site. From this work, it has been established thatB-site disorder restores the dipole-like behaviour of the Nd⁺³ions compared to the Nd₂B₂O₇parent series.

Possible itinerant excitations and quantum spin state transitions in the effective spin-1/2 triangular-lattice antiferromagnet Na2BaCo(PO4)2

The most fascinating feature of certain two-dimensional (2D) gapless quantum spin liquid (QSL) is that their spinon excitations behave like the fermionic carriers of a paramagnetic metal. The spinon Fermi surface is then expected to produce a linear increase of the thermal conductivity with temperature that should manifest via a residual value (κ₀/T) in the zero-temperature limit. However, this linear in T behavior has been reported for very few QSL candidates. Here, we studied the ultralow-temperature thermal conductivity of an effective spin-1/2 triangular QSL candidate Na₂BaCo(PO₄)₂, which has an antiferromagnetic order at very low temperature (T_N ~ 148 mK), and observed a finite κ₀/T extrapolated from the data above T_N. Moreover, while approaching zero temperature, it exhibits series of quantum spin state transitions with applied field along the c axis. These observations indicate that Na₂BaCo(PO₄)₂ possibly behaves as a gapless QSL with itinerant spin excitations above T_N and its strong quantum spin fluctuations persist below T_N.

The nature of spin excitations in the one-third magnetization plateau phase of Ba3CoSb2O9

Magnetization plateaus in quantum magnets—where bosonic quasiparticles crystallize into emergent spin superlattices—are spectacular yet simple examples of collective quantum phenomena escaping classical description. While magnetization plateaus have been observed in a number of spin-1/2 antiferromagnets, the description of their magnetic excitations remains an open theoretical and experimental challenge. Here, we investigate the dynamical properties of the triangular-lattice spin-1/2 antiferromagnet Ba₃CoSb₂O₉ in its one-third magnetization plateau phase using a combination of nonlinear spin-wave theory and neutron scattering measurements. The agreement between our theoretical treatment and the experimental data demonstrates that magnons behave semiclassically in the plateau in spite of the purely quantum origin of the underlying magnetic structure. This allows for a quantitative determination of Ba₃CoSb₂O₉ exchange parameters. We discuss the implication of our results to the deviations from semiclassical behavior observed in zero-field spin dynamics of the same material and conclude they must have an intrinsic origin.

Frustrated magnetic materials attract significant interest because their properties can become dominated by quantum fluctuations. Here the authors show that excitations in the plateau phase of a quantum magnet can be understood semiclassically even though the ground state involves strong quantum effects.

Field-Driven Quantum Criticality in the Spinel Magnet ZnCr_{2}Se_{4}

We report detailed dc and ac magnetic susceptibilities, specific heat, and thermal conductivity measurements on the frustrated magnet ZnCr_{2}Se_{4}. At low temperatures, with an increasing magnetic field, this spinel material goes through a series of spin state transitions from the helix spin state to the spiral spin state and then to the fully polarized state. Our results indicate a direct quantum phase transition from the spiral spin state to the fully polarized state. As the system approaches the quantum criticality, we find strong quantum fluctuations of the spins with behaviors such as an unconventional T^{2}-dependent specific heat and temperature-independent mean free path for the thermal transport. We complete the full phase diagram of ZnCr_{2}Se_{4} under the external magnetic field and propose the possibility of frustrated quantum criticality with extended densities of critical modes to account for the unusual low-energy excitations in the vicinity of the criticality. Our results reveal that ZnCr_{2}Se_{4} is a rare example of a 3D magnet exhibiting a field-driven quantum criticality with unconventional properties.

Canted magnetic ground state of quarter-doped manganites R 0.75Ca0.25MnO3 (R = Y, Tb, Dy, Ho, and Er)

Polycrystalline samples of the quarter-doped manganites R _0.75Ca_0.25MnO₃ (R  =  Y, Tb, Dy, Ho, and Er) were studied by x-ray diffraction and AC/DC susceptibility measurements. All five samples are orthorhombic and exhibit similar magnetic properties: enhanced ferromagnetism below T ₁ (∼80 K) and a spin glass (SG) state below T _SG (∼30 K). With increasing R ³⁺ ionic size, both T ₁ and T _SG generally increase. The single crystal neutron diffraction results on Tb_0.75Ca_0.25MnO₃ revealed that the SG state is mainly composed of a short-range ordered version of a novel canted (i.e. noncollinear) antiferromagnetic spin state. Furthermore, calculations based on the double exchange model for quarter-doped manganites reveal that this new magnetic phase provides a transition state between the ferromagnetic state and the theoretically predicted spin-orthogonal stripe phase.

Magnetism and multiferroicity of an isosceles triangular lattice antiferromagnet Sr3NiNb2O9

Various experimental measurements were performed to complete the phase diagram of a weakly distorted triangular lattice system, Sr3NiNb2O9 with Ni(2+) , spin-1 magnetic ions. This compound possesses an isosceles triangular lattice with two shorter bonds and one longer bond. It shows a two-step magnetic phase transition at [Formula: see text] K and [Formula: see text] K at zero magnetic field, characteristic of an easy-axis anisotropy. In the magnetization curves, a series of magnetic phase transitions was observed such as an up-up-down phase at [Formula: see text] T with 1/3 of the saturation magnetization (M sat) and an oblique phase at [Formula: see text] T with [Formula: see text]/3 M sat. Intriguingly, the magnetic phase transition below T N2 is in tandem with the ferroelectricity, which demonstrates multiferroic behaviors. Moreover, the multiferroic phase persists in all magnetically ordered phases regardless of the spin structure. The comparison between the phase diagrams of Sr3NiNb2O9 and its sister compound with an equilateral triangular lattice antiferromagnet Ba3NiNb2O9 (Hwang et al 2012 Phys. Rev. Lett. 109 257205), illustrates how a small imbalance among exchange interactions change the magnetic ground states of the TLAFs.

Magnetic Ground States of the Rare-Earth Tripod Kagome Lattice Mg_{2}RE_{3}Sb_{3}O_{14} (RE=Gd,Dy,Er)

We present the structural and magnetic properties of a new compound family, Mg_{2}RE_{3}Sb_{3}O_{14} (RE=Gd,Dy,Er), with a hitherto unstudied frustrating lattice, the "tripod kagome" structure. Susceptibility (ac, dc) and specific heat exhibit features that are understood within a simple Luttinger-Tisza-type theory. For RE=Gd, we found long-ranged order (LRO) at 1.65 K, which is consistent with a 120° structure, demonstrating the importance of diople interactions for this 2D Heisenberg system. For RE=Dy, LRO at 0.37 K is related to the "kagome spin ice" physics for a 2D system. This result shows that the tripod kagome structure accelerates the transition to LRO predicted for the related pyrochlore systems. For RE=Er, two transitions, at 80 mK and 2.1 K are observed, suggesting the importance of quantum fluctuations for this putative XY system.

Dimerization-induced Fermi-surface reconstruction in IrTe2

We report a de Haas-van Alphen (dHvA) oscillation study on IrTe2 single crystals showing complex dimer formations. By comparing the angle dependence of dHvA oscillations with band structure calculations, we show distinct Fermi surface reconstruction induced by a 1/5-type and a 1/8-type dimerizations. This verifies that an intriguing quasi-two-dimensional conducting plane across the layers is induced by dimerization in both cases. A phase transition to the 1/8 phase with higher dimer density reveals that local instabilities associated with intra- and interdimer couplings are the main driving force for complex dimer formations in IrTe2.

Incipient ferromagnetism in Tb2Ge2O7: application of chemical pressure to the enigmatic spin-liquid compound Tb2Ti2O7

After nearly 20 years of study, the origin of the spin-liquid state in Tb2Ti2O7 remains a challenge for experimentalists and theorists alike. To improve our understanding of the exotic magnetism in Tb2Ti2O7, we synthesize a chemical pressure analog: Tb2Ge2O7. Substitution of titanium by germanium results in a lattice contraction and enhanced exchange interactions. We characterize the magnetic ground state of Tb2Ge2O7 with specific heat, ac and dc magnetic susceptibility, and polarized neutron scattering measurements. Akin to Tb2Ti2O7, there is no long-range order in Tb2Ge2O7 down to 20 mK. The Weiss temperature of -19.2(1)  K, which is more negative than that of Tb2Ti2O7, supports the picture of stronger antiferromagnetic exchange. Polarized neutron scattering of Tb2Ge2O7 reveals that liquidlike correlations dominate in this system at 3.5 K. However, below 1 K, the liquidlike correlations give way to intense short-range ferromagnetic correlations with a length scale similar to the Tb-Tb nearest neighbor distance. Despite stronger antiferromagnetic exchange, the ground state of Tb2Ge2O7 has ferromagnetic character, in stark contrast to the pressure-induced antiferromagnetic order observed in Tb2Ti2O7.

Valley-polarized interlayer conduction of anisotropic Dirac fermions in SrMnBi2

We report the valley-selective interlayer conduction of SrMnBi(2) under in-plane magnetic fields. The c-axis resistivity of SrMnBi(2) shows clear angular magnetoresistance oscillations indicating coherent interlayer conduction. Strong fourfold variation of the coherent peak in the c-axis resistivity reveals that the contribution of each Dirac valley is significantly modulated by the in-plane field orientation. This originates from anisotropic Dirac Fermi surfaces with strong disparity in the momentum-dependent interlayer coupling. Furthermore, we found a signature of broken valley symmetry at high magnetic fields. These findings demonstrate that a quasi-two-dimensional anisotropic Dirac system can host a valley-polarized interlayer current through magnetic valley control.

Quantum oscillations of the metallic triangular-lattice antiferromagnet PdCrO2

We report the electronic and transport properties of the triangular antiferromagnet PdCrO(2) at high magnetic fields up to 33 T, using measurements of the de Haas-van Alphen oscillations and the Hall resistivity. The de Haas-van Alphen oscillations below the magnetic ordering temperature T(N) reveal several two-dimensional Fermi surfaces of smaller size than those found in nonmagnetic PdCoO(2), consistent with the band structure calculations. This evidences Fermi surface reconstruction due to the 120° helical ordering of the localized Cr spins, suggesting significant coupling of the itinerant electrons to the underlying spin texture. This induces the nonlinear Hall resistivity at low temperatures via the magnetic breakdown in the reconstructed Fermi surface. Furthermore, such a coupling leads to the unconventional anomalous Hall effects near T(N) due to the field-induced spin chirality at high magnetic fields.

Successful rescue of early graft failure in pediatric patients using T-cell-depleted haploidentical hematopoietic SCT

Graft failure (GF) is a significant complication after allogeneic hematopoietic stem cell transplantation (HCT) and is associated with a high mortality rate. We performed re-transplantation using haploidentical-related donors to rescue children with early GF. Between 2008 and 2013, 10 patients received re-transplantation from haploidentical family donors. The median age at HCT was 13.5 years and the median time between transplantations was 52.5 days. Conditioning regimen with fludarabine and CY was used in seven patients, and TBI was added in three patients. All 10 patients received T-cell-depleted grafts using CD3 or CD3/CD19 MoAb. The median numbers of CD34(+) and CD3(+) cells were 5.52 × 10(6)/kg and 1.08 × 10(6)/kg, respectively. For GVHD prophylaxis, mycophenolate mofetil (MMF) and tacrolimus or MMF and CYA were used. All 10 patients achieved a sustained neutrophil engraftment and maintained a complete donor chimerism at the time of analysis (median 23 months, range 6-62 months). Nine of 10 patients were alive, and one patient with moyamoya disease with AML died of encephalopathy 7 months post transplant. This study suggests that fludarabine- and CY-based conditioning with T-cell-depleted haploidentical HCT is a feasible option to rescue pediatric patients with primary GF.

Electronic Griffiths phase in the Te-doped semiconductor FeSb2

We report on the emergence of an electronic Griffiths phase in the doped semiconductor FeSb(2), predicted for disordered insulators with random localized moments in the vicinity of a metal-insulator transition. Magnetic, transport, and thermodynamic measurements of Fe(Sb(1-x)Te(x))(2) single crystals show signatures of disorder-induced non-Fermi liquid behavior and a Wilson ratio expected for strong electronic correlations. The electronic Griffiths phase states are found on the metallic boundary between the insulating state (x = 0) and a long-range albeit weak magnetic order (x ≥ 0.075).

Successive magnetic phase transitions and multiferroicity in the spin-one triangular-lattice antiferromagnet Ba3NiNb2O9

We report the magnetic and electric properties of Ba3NiNb2O9, which is a quasi-two-dimensional spin-one triangular-lattice antiferromagnet with trigonal structure. At low T and with increasing magnetic field, the system evolves from a 120 degree magnetic ordering phase (A phase) to an up-up-down (uud) phase (B phase) with a change of slope at 1/3 of the saturation magnetization, and then to an "oblique" phase (C phase). Accordingly, the ferroelectricity switches on at each phase boundary with appearance of spontaneous polarization. Therefore, Ba3NiNb2O9 is a unique triangular-lattice antiferromagnet exhibiting both uud phase and multiferroicity.

The angular magnetothermoelectric power of a charge density wave system

The angular dependence of the magnetothermopower of a charge transfer organic salt α-(ET)(2)KHg(SCN)(4) below (4 K) and above (9 K) the phase transition temperature, T(p) = 8 K, and under fields of 15 T and 25 T, below and above the 'kinkfield', has been studied. We find that for a longitudinal thermoelectric measurement both an interlayer thermopower (the Seebeck effect), S(zz), and a transverse thermopower (the Nernst effect), S(yz), exist in all three different B-T phases (the CDW (0), CDW (x) and metallic states) with large amplitude. Both thermoelectric effects display a resonant-like behavior without a sign reversal at the angles corresponding to angular magnetoresistance oscillation minima and maxima in this compound. The resonant behavior is most evident in the CDW(0) state, indicating a mechanism involving the Fermi surface nesting. Angular dependences reveal different behaviors of the thermopower and Nernst effect in the high magnetic field (CDW(x)) state.

Chemical pressure effects on pyrochlore spin ice

A comparison among the two sets of studied pyrochlore spin ices, Ho2Sn2O7, Ho2Ti2O7, and Ho2Ge2O7 with Ho3+ spins and Dy2Sn2O7, Dy2Ti2O7, and Dy2Ge2O7 with Dy3+ spins, shows that the application of chemical pressure through each set drives the system toward the antiferromagnetic phase boundary from the spin ice region, which agrees with the prediction of the "dipolar spin ice" model of den Hertog and Gingras. Among all the studied pyrochlore spin ices, Dy2Ge2O7 has the smallest ratio of Jnn/Dnn=-0.73.

Skyrmions in a doped antiferromagnet

Magnetization and magnetoresistance have been measured in insulating antiferromagnetic La2Cu0.97Li0.03O4 over a wide range of temperatures, magnetic fields, and field orientations. The magnetoresistance step associated with a weak ferromagnetic transition exhibits a striking nonmonotonic temperature dependence, consistent with the presence of Skyrmions.

Spin liquid state in the S = 1/2 triangular lattice Ba3CuSb2O9

The synthesis and characterization of Ba3CuSb2O9, which has a layered array of Cu2+ spins in a triangular lattice, are reported. The magnetic susceptibility and neutron scattering experiments of this material show no magnetic ordering down to 0.2 K with a θ(CW) = -55  K. The magnetic specific heat reveals a T-linear dependence with a γ = 43.4  mJ  K(-2)  mol(-1) below 1.4 K. These observations suggest that Ba3CuSb2O9 is a new quantum spin liquid candidate with a S = 1/2 triangular lattice.

Synthesis and electrochemical properties of LiMPO4 (M = Fe, Mn, Co) nanocrystals in polyol medium

Olivine structured LiMPO4 (M = Fe, Mn, Co) was synthesized by the solvothermal process using a polyol medium of diethylene glycol (DEG) without any further heating as a post procedure. The synthesized LiMPO4 nanoparticles exhibited an average length of 200 approximately 400 nm, width of 200 approximately 300 nm, and thickness of 20 approximately 50 nm, and with well dispersed plate and rod morphologies. The Rietveld-refined X-ray diffraction (XRD) pattern of LiFePO4 exhibited a good fit with an olivine structure (space group: Pnma) and no undesirable impurity phases. The LiFePO4 nanocrystals showed a reversible capacity of 167 mAh/g, equating to a utilization efficiency of 98% of its theoretical capacity, with a good cyclability over an extended range up to 40 cycles.

Synthesis and electrochemical properties of LiFePO4/carbon nanocomposites in polyol medium

LiFePO4/Carbon nanocomposites with varying amounts of carbon were synthesized using polyol process without any further heating as a post step. The X-ray diffraction patterns of all samples were indexed on the basis of orthorhombic olivine-type structure. The field emission-TEM images of composites with the amount of 3 approximately 15 wt% carbon showed the average sizes of 45 approximately 80 nm with nanorod shape surrounded by carbon. The initial discharge curves of LiFePO4/Carbon show 166, 157, 142, and 119 mAh/g capacities at a current density of 0.1 mA/cm2 in the voltage range of 2.5-4.2 V, respectively, without capacity fading and excellent cycle retentions during the 20 cycles. Especially, the sample of amount of 3 wt% carbon shows the excellent high rate performances at 15 and 30 C rates with high capacity retention compared with previously reported results of high temperature processed results, due to the existence of conductive agents such as carbon which suppresses particle growth and exhibits improved electronic conductivity and lithium ion diffusivity, simultaneously.

Light-extraction enhancement of red AlGaInP light-emitting diodes with antireflective subwavelength structures

We demonstrate the enhancement of light extraction in 633 nm AlGaInP light-emitting diodes (LEDs) with antireflective subwavelength structures (SWS). From the contour plots by the rigorous coupled wave analysis method, it is found that the reduction of the internal reflection strongly depends on the period of SWS. The Ag nanoparticles formed by thermal dewetting were used as an etch mask for dry etch process to fabricate antireflective SWS on the LED surface. The tapered pillars on the GaP were fabricated, on average, with distances below 200 nm, satisfying the required antireflection condition at the emission wavelength. The improvement in light output power by approximately 26.4% was achieved for the fabricated AlGaInP LEDs with SWS compared to the conventional LEDs due to a strongly reduced Fresnel internal reflection at the GaP/air interface. The improved directionality in the far-field pattern was also obtained due to the directional light extraction enhancement.

Optical approach to the periodontal ligament under orthodontic tooth movement: a preliminary study with optical coherence tomography

INTRODUCTION

Optical coherence tomography (OCT) is a diagnostic tool that can make near-histologic tomographic images without a biohazard. Due to its high resolution (average, 4 microm) and safety (using light as the source), it has been applied widely in medical fields to replace invasive biopsies. But the trials in dentistry have been restricted to mainly detecting dental caries and oral cancer. In this preliminary study for successive human studies, we tried to evaluate whether OCT can be helpful in determining tooth movement under light orthodontic forces.

METHODS

Orthodontic distraction forces (0, 5, and 10 g) were applied to the mandibular incisors of 6 white rats (10 weeks old) for 5 days by using individualized loop springs (round Elgiloy, 0.018-in diameter, Rocky Mountain Orthodontics, Denver, Colo). The changed periodontal ligaments were imaged with OCT and digital intraoral radiography 2 dimensionally. Both tensile and compressive ligaments were measured and compared.

RESULTS

With OCT images, we could measure changed ligaments from all directions; radiography could not show the portions overlapped by teeth. The averages of measured ligament width in OCT were larger than those from radiography in all groups.

CONCLUSIONS

This preliminary study shows the possible evaluation and prediction of precise tooth responses under orthodontic forces by using real-time OCT.

Symptomatic nerve root changes on contrast-enhanced MR imaging after surgery for lumbar disk herniation

BACKGROUND AND PURPOSE

The significance of postoperative nerve root changes (enhancement, thickening, and displacement) is still a topic of debate. The purpose of this study was to evaluate the association between nerve root changes and residual or recurrent symptoms after lumbar surgery with contrast-enhanced MR imaging.

MATERIALS AND METHODS

A total of 120 patients with 140 postoperative lumbar disk lesions causing residual or recurrent pain underwent contrast-enhanced MR imaging. The levels at which diskectomies had been performed were retrospectively evaluated for nerve root enhancement (NRE), thickening, and displacement. Association between nerve root changes and corresponding clinical presentations were statistically assessed. Nerve root changes in recurrent disk herniation (RDH) and postoperative epidural fibrosis (PEF) were also evaluated with clinical symptoms.

RESULTS

Ninety-two (65.7%) of the 140 disks demonstrated NRE. Regarding the association with clinical symptoms, the sensitivity was 91.7%, the specificity was 73.2%, the positive predictive value (PPV) was 83.7%, and the negative predictive value was 85.4% (P = .000). Nerve root thickening and displacement were significantly associated with the clinical symptoms, especially when NRE was combined (PPV, 87.7% and 87.2%, respectively). When RDH was combined with all 3 nerve root changes, the PPV was increased up to 94.1%. However, in PEF, the association between nerve root changes and clinical symptoms was not significant unless all 3 nerve root changes were combined.

CONCLUSIONS

In patients with residual or recurrent pain after surgery for lumbar disk herniation, nerve root changes on contrast-enhanced MR imaging were well associated with clinical symptoms, of which NRE was the most significant finding.

TLR9 is expressed in idiopathic interstitial pneumonia and its activation promotes in vitro myofibroblast differentiation

Infectious diseases can be cofactors in idiopathic interstitial pneumonias (IIP) pathogenesis; recent data suggests that toll-like receptors 9 (TLR9) ligands contribute to experimental chronic tissue remodeling. Real-time TAQMAN and immunohistochemical analysis of IIP normal surgical lung biopsies (SLBs), primary fibroblast lines grown from both IIP and normal SLBs indicate that TLR9 is prominently and differentially expressed in a disease-specific manner. TLR9 expression was increased in biopsies from patients with IIP compared with normal lung biopsies and its expression is localized to areas of marked interstitial fibrosis. TLR9 in fibroblasts appeared to be increased by profibrotic Th2 cytokines (IL-4 and IL-13) and this was true in fibroblasts cultured from the most severe form of IIP, idiopathic pulmonary fibrosis (IPF) SLBs, in non-specific interstitial pneumonia fibroblast lines, and in normal fibroblasts. Finally, confocal microscopy studies have shown that TLR9 activation by its synthetic agonist CpG-ODN significantly increased the expression of alpha smooth muscle actin, the main marker of myofibroblast differentiation. These data indicate that TLR9 expression may drive the abnormal tissue healing response in severe forms of IIP and its activation can have a key role in myofibroblast differentiation promoting the progression of disease during the terminal phase of IPF.

Antiferromagnetic d-electron exchange via a spin-singlet pi-electron ground state in an organic conductor

Electron spin resonance reveals the spin behavior of conduction (pi) and localized (d) electrons in beta-(BDA-TTP)2MCl4 (M=Fe, Ga). Both the Ga3+(S=0) and Fe3+(S=5/2) compounds exhibit a metal-insulator transition at 113 K with the simultaneous formation of a spin-singlet ground state in the pi electron system of the donor molecules. The behavior is consistent with charge ordering in beta-(BDA-TTP)2MCl4 at the metal-insulator transition. At 5 K, the Fe3+ compound orders antiferromagnetically, even though the pi electrons, which normally would facilitate magnetic exchange, are localized nonmagnetic singlets.

Vortex dynamics and the Fulde-Ferrell-Larkin-Ovchinnikov state in a magnetic-field-induced organic superconductor

Under special conditions, a superconducting state where the order parameter oscillates in real space, the so-called FFLO state, is theoretically predicted to exist near the upper critical field, as first proposed by Fulde and Ferrell, and Larkin and Ovchinnikov. We report systematic measurements of the interlayer resistance in high magnetic fields to 45 T in the two-dimensional magnetic-field-induced organic superconductor lambda-(BETS)2FeCl4, where BETS is bis(ethylenedithio)tetraselenafulvalene. The resistance is found to show characteristic dip structures in the superconducting state. The results are consistent with pinning interactions between the vortices penetrating the insulating layers and the order parameter of the FFLO state. This gives strong evidence for an oscillating order parameter in real space.

Focal interstitial CC chemokine receptor 7 (CCR7) expression in idiopathic interstitial pneumonia

BACKGROUND/AIMS

Idiopathic interstitial pneumonias (IIPs) are a diverse grouping of chronic pulmonary diseases characterised by varying degrees of pulmonary fibrosis. The triggers of the fibroproliferative process in IIP remain enigmatic but recent attention has been directed towards chemokine involvement in this process.

METHODS

The expression of two chemokine receptors, CCR7 and CXCR4, and their respective ligands, CCL19, CCL21, and CXCL12, were examined in surgical lung biopsies (SLBs) from patients with IIP. Transcript and protein expression of these receptors and their ligands was compared with that detected in histologically normal margin SLBs.

RESULTS

CCR7 and CXCR4 were detected by gene array and real time polymerase chain reaction analysis and CCR7, but not CXCR4, expression was significantly raised in usual interstitial pneumonia (UIP) relative to biopsies from patients diagnosed with non-specific interstitial pneumonia (NSIP) or respiratory bronchiolitis/interstitial lung disease (RBILD). CCR7 protein was expressed in interstitial areas of all upper and lower lobe UIP SLBs analysed. CCR7 expression was present in 50% of NSIP SLBs, and CCR7 was restricted to blood vessels and mononuclear cells in 75% of RBILD SLBs. Immune cell specific CXCR4 expression was seen in IIP and normal margin biopsies. CCR7 positive areas in UIP biopsies were concomitantly positive for CD45 (the leucocyte common antigen) but CCR7 positive areas in all IIP SLBs lacked the haemopoietic stem cell antigen CD34, collagen 1, and alpha smooth muscle actin.

CONCLUSION

This molecular and immunohistochemical analysis showed that IIPs are associated with abnormal CCR7 transcript and protein expression.

Resonant nernst effect in the metallic and field-induced spin density wave States of (TMTSF)2ClO4

We examine an unusual phenomenon where, in tilted magnetic fields near magic angles parallel to crystallographic planes, a "giant" resonant Nernst signal has been observed by Wu et al. [Phys. Rev. Lett. 91, 056601 (2003)] in the metallic state of an organic conducting Bechgaard salt. We show that this effect appears to be a general feature of these materials and is also present in the field-induced spin density wave phase with even larger amplitude. Our results place conditions on any model that treats the metallic state as a state with finite Cooper pairing.

Quantum oscillation of Hall resistance in the extreme quantum limit of an organic conductor (TMTSF)2ClO4

We report resistance and magnetic torque experiments under a high magnetic field up to 45 T in a three dimensional quantum Hall (QH) system (TMTSF)(2)ClO(4), where TMTSF = tetramethyltetraselenafulvalene. The Hall resistance shows huge oscillations accompanied with sign reversal after the final QH state, where the Landau level filling factor is unity, is removed above 26 T. The magnetic torque also oscillates with the field. The results suggest that a novel quantum state, where the character of the carriers periodically changes with the field, is stabilized in the extreme quantum limit.

High magnetic field induced charge density wave state in a quasi-one-dimensional organic conductor

The quasi-one-dimensional organic conductor (Per)2Pt(mnt)2 exhibits a charge density wave ground state below 8 K. Magnetoresistance and magnetization measurements show that the charge density wave is suppressed with magnetic fields of order 20 T, above which a high resistance state, with a cascade of subphases, appears. This new state, tentatively identified as a field induced charge density wave, reenters a low resistance state above 40 T. The results are presented in light of theoretical work [D. Zanchi et al. Phys. Rev. B 53, 1240 (1996)]] involving field induced charge density wave ground states in high magnetic fields.

Augmented pulmonary IL-4 and IL-13 receptor subunit expression in idiopathic interstitial pneumonia

BACKGROUND

Some idiopathic interstitial pneumonias (IIPs) are characterised by fibroproliferation and deposition of extracellular matrix. Because efficacious treatment options are limited, research has been directed towards understanding the cytokine networks that may affect fibroblast activation and, hence, the progression of certain IIPs.

AIMS

To examine the expression of interleukin 4 (IL-4), IL-13, and their corresponding receptor subunits in the various forms of IIP and normal patient groups.

METHODS

Molecular and immunohistochemical analysis of IL-4, interferon gamma (IFNgamma), IL-13, IL-4 receptor (IL-R), and IL-13 receptor subunits in surgical lung biopsies (SLBs) from 39 patients (21 usual interstitial pneumonia (UIP), six non-specific interstitial pneumonia (NSIP), eight respiratory bronchiolitic interstitial lung disease (RBILD), and five normal controls).

RESULTS

Molecular analysis demonstrated that IL-13Ralpha2, IL-13Ralpha1, and IL-4Ralpha were present in a greater proportion of upper and lower lobe biopsies from patients with UIP than patients with NSIP and RBILD. Immunohistochemical analysis of patients with UIP, NSIP, and RBILD revealed interstitial staining for all three receptor subunits, whereas such staining was only seen in mononuclear cells present in normal SLBs. Fibroblastic foci in patients with UIP strongly stained for IL-4Ralpha and IL-13Ralpha2. Localised expression of IL-4Ralpha was also seen in SLBs from patients with NSIP but not in other groups.

CONCLUSION

Some histological subtypes of IIP are associated with increased pulmonary expression of receptor subunits responsive to IL-4 and IL-13. These findings may be of particular importance in understanding the pathogenesis of IIP and, more importantly, may provide important novel therapeutic targets.

Enhanced secretion of Bacillus stearothermophilus L1 lipase in Saccharomyces cerevisiae by translational fusion to cellulose-binding domain

The secretion of Bacillus stearothermophilus L1 lipase in Saccharomyces cerevisiae was investigated by employing a fusion partner, a cellulose-binding domain (CBD) from Trichoderma harzianum endoglucanase II (THEG). The CBD was connected to the N-terminal of L1 lipase through an endogenous linker peptide from THEG. The expression cassette for the fusion protein in S. cerevisiae was constructed using the alpha-amylase signal peptide and the galactose-inducible GAL10 promoter. Secretion of CBD-linker-L1 lipase by this fusion construct was dramatically 7-fold enhanced, compared with that of the mature L1 lipase without CBD-fusion. The fusion protein was secreted into the culture medium, reaching levels of approximately 1.3 g/l in high-cell-density fed-batch cultures. Insertion of a KEX2 cleavage site into the junction between CBD-linker and L1 lipase resulted in the same level of enhanced secretion, indicating that the CBD-linker fusion probably plays a critical role in secretion from endoplasmic reticulum to Golgi apparatus. Therefore, the CBD from THEG can be used both as an affinity tag and as a secretion enhancer for the secretory production of heterologous proteins in S. cerevisiae, since in vivo breakage at the linker was almost negligible.

Independent Exponential Feeding of Glycerol and Methanol for Fed-Batch Culture of Recombinant Hansenula polymorpha DL-1

As a novel feeding strategy for optimizing human epidermal growth factor (hEGF) production with a recombinant Hansenula polymorpha DL-1 using the methanol oxidase (MOX) promoter in H. polymorpha DL-1, independent exponential feeding of two substrates was used. A simple kinetic model considering the cell growth on two substrates was established and used to calculate the respective feeding rates of glycerol and methanol. In the fedbatch culture with methanol-only feeding, the optimal set point of specific growth rate on methanol was found to be 0.10 h-1. When the fed-batch cultures were conducted by the independent feeding of glycerol and methanol, the actual specific growth rate on glycerol and methanol was slightly lower than the set point of specific growth rate. By the uncoupled feeding of glycerol and methanol the volumetric productivity of hEGF increased from 6.4 to 8.0 mg/(L.h), compared with methanol-only feeding.

[A novel approach to isolation and functional characterization of genomic DNA from the methylotrophic yeast Hansenula polymorpha]

A novel approach to isolation and functional characterization of the Hansenula polymorpha genes basing on the use of two strains of different origin is described. One of these strains is better suited for the isolation of genomic DNA fragments, while the other is preferable for their functional analysis. Thirty three genomic sequences governing expression of a reporter protein have been isolated. Analysis of the sequence encoding a homolog of the Saccharomyces cerevisiae cofilin revealed two introns. Another isolated DNA fragment encoded a homolog of the S. cerevisiae V ps10p. Disruption of the corresponding gene resulted in secretion of a vacuolar protein, carboxypeptidase Y, into the culture medium.

Current status of the anticoagulant hirudin: its biotechnological production and clinical practice

Hirudin is a potent thrombin inhibitor originally derived from the medicinal leech, Hirudo medicinalis. Owing to its high affinity and specificity for thrombin, hirudin has been intensively investigated for research and therapeutic purposes. The investigation of hirudin has contributed greatly to the understanding of the mode of action of thrombin and the clotting system. Hirudin and several hirudin analogues have also been demonstrated to have several advantages as a highly specific anticoagulant over the most widely used drug, heparin. Due to the great demand for hirudin in physicochemical and clinical studies, various recombinant systems have been developed, using bacteria, yeasts, and higher eukaryotes, to obtain the biologically active hirudin in significant quantities. After 10 years of clinical applications, two recombinant hirudins and a hirudin analogue have gained marketing approval from the United States Food and Drug Administration, for several applications. Clinical trials are currently ongoing for other treatments for thrombotic disease. As a consequence, it is conceivable that hirudin may expand its therapeutic utility over heparin in the near future.

Galactosylated chitosan-graft-poly(ethylene glycol) as hepatocyte-targeting DNA carrier

Lactobionic acid bearing galactose group was coupled with chitosan for liver specificity, and poly(ethylene glycol) (PEG) was grafted to galactosylated chitosan (GC) for stability in water and enhanced cell permeability. Complex formation of galactosylated chitosan-graft-PEG (GCP)/DNA complexes was confirmed by agarose gel electrophoresis. Compared to GC/DNA complex, the stability of GCP/DNA complex could be enhanced. Particle sizes of GCP/DNA complexes decreased as the charge ratio of GCP to DNA increased and had a minimum value around 27 nm at the charge ratio of 5. Conformational change of DNA did not occur after complex formation with GCP compared to conformation of DNA itself. GCP/DNA complexes were only transfected into Hep G2 having asialoglycoprotein receptors (ASGR), indicative of specific interaction of ASGR on cells and galactose ligands on GCP.

Development of expression systems for the production of recombinant human serum albumin using the MOX promoter in Hansenula polymorpha DL-1

To optimize the secretory expression of recombinant human serum albumin (HSA) under the control of methanol oxidase (MOX) promoter in the methylotrophic yeast Hansenula polymorpha DL-1, we analyzed several parameters affecting the expression of HSA from the MOX promoter. Removal of the 5'-untranslated region derived from HSA cDNA in the expression cassette led to at least a fivefold improvement of HSA expression efficiency at the translational level. With the optimized expression cassette, the gene dosage effect on HSA expression was abolished and thus, a single copy of the expression vector integrated into the MOX locus became sufficient for the maximal expression of HSA. Northern blot analysis revealed that the levels of HSA transcript did not increase any further upon increasing copy number. The mox-disrupted (mox Delta) transformant was constructed, in which the genomic MOX gene was transplaced with the HSA expression cassette, to examine the effect of the methanol oxidase-deficient phenotype of the host on HSA expression. The mox Delta transformant showed higher levels of HSA production in shake-flask cultures than the MOX wild-type transformant, especially at low concentrations of methanol and a twofold higher specific HSA production rate in fed-batch fermentation with an abrupt induction mode. The native prepro signal sequence of HSA secreted in H. polymorpha was correctly processed and the mature recombinant protein had a pI value identical to that of the authentic HSA. Our results suggest that the H. polymorpha expression systems developed in this study are suitable for large-scale production of recombinant albumin.

Molecular characterization of the actin-encoding gene and the use of its promoter for a dominant selection system in the methylotrophic yeast Hansenula polymorpha

The actin gene (ACT) from the methylotrophic yeast Hansenula polymorpha was cloned and its structural feature was characterized. In contrast to the actin genes of other ascomycetous yeasts, which have only one large intron, the H. polymorpha ACT gene was found to be split by two introns. The H. polymorpha ACT introns were correctly processed in the heterologous host Saccharomyces cerevisiae despite appreciable differences in the splice site sequences. The promoter region of H. polymorpha ACT displayed two CCAAT motifs and two TATA-like sequences in a configuration similar to that observed in the S. cerevisiae actin promoter. A set of deleted H. polymorpha ACT promoters was exploited to direct expression of the bacterial hygromycin B resistance (hph) gene as a dominant selectable marker in the transformation of H. polymorpha. The resistance level of H. polymorpha transformants to the antibiotic was shown to be dependent on the integration copy number of the hph cassette. The selectivity of the hygromycin B resistance marker for transformants of higher copy number was remarkably increased with the deletion of the upstream TATA-like sequence, but not with the removal of either CCAAT motif, from the H. polymorpha promoter. The dosage-dependent selection system developed in this study should be useful for genetic manipulation of H. polymorpha as an industrial strain to produce recombinant proteins.

Cloning and characterization of the Hansenula polymorpha homologue of the Saccharomyces cerevisiae MNN9 gene

A gene homologous to Saccharomyces cerevisiae MNN9 has been cloned and characterized in the methylotrophic yeast Hansenula polymorpha. This gene was cloned from a H. polymorpha genomic DNA library using the S. cerevisiae MNN9 gene as a probe. The H. polymorpha MNN9 homologue (HpMNN9) contained a 1062 bp open reading frame encoding a predicted protein of 354 amino acids. The deduced amino acid sequence showed 58% and 51% identity, respectively, with the S. cerevisiae and Candida albicans Mnn9 proteins. Disruption of HpMNN9 leads to phenotypic effects suggestive of cell wall defects, including detergent sensitivity and hygromycin B sensitivity. The hygromycin B sensitivity of S. cerevisiae mnn9 null mutant was complemented in the presence of the HpMNN9 gene. The DNA sequence of the H. polymorpha homologue has been submitted to GenBank with the Accession No. AF264786.

Mutation of the homologue of GDP-mannose pyrophosphorylase alters cell wall structure, protein glycosylation and secretion in Hansenula polymorpha

A Hansenula polymorpha mutant with enhanced ability to secrete a heterologous protein has been isolated. The mutation defines a gene, designated OPU24, which encodes a protein highly homologous to GDP-mannose pyrophosphorylase Psa1p/Srb1p/Vig9p of Saccharomyces cerevisiae and CaSrb1p of Candida albicans. The opu24 mutant manifests phenotypes similar to those of S. cerevisiae mutants depleted for GDP-mannose, such as cell wall fragility and defects in N- and O-glycosylation of secreted proteins. The influence of the opu24 mutation on endoplasmic reticulum-associated protein degradation is discussed. The GenBank Accession No. for the OPU24 sequence is AF234177.

Removal of odor emitted from composting facilities using a porous ceramic biofilter

A field experiment was conducted using a full-scale ceramic biofilter (approximately 150 m3/min) in order to determine the potential for biofiltration to remove malodorous gases from composting facilities. The main compounds found in malodorous gases were NH3 and H2S. These compounds were analyzed by a UV-spectrophotometer and gas chromatograph. The microbial carrier was a porous ceramic consisting of diatomite and fly ash. About 12 m3 of ceramic media inoculated with waste activated sludge were filled in the biofilter. The experimental conditions were space velocity of 500 hr(-1), empty bed residence time of 7.2 s, and linear velocity of 0.2 m/s. About 90 L/d of water were sprayed for the operation. The NH3 concentration in inlet gases ranged from 8 to 90 ppmv. The concentration of H2S ranged from 3.2-5.5 ppmv. The acclimation of the biofilter was slow, but more than 95% of removal efficiency was achieved after one month of operation. No nutrients were supplied to the biofilter. The pressure drop in the biofilter varied from 20-40 mmAq during the operation. The energy consumption of this biofilter was about 200 kW/d. It was estimated that the deodorization using this ceramic biofilter was successfully carried out to remove the odor emitted from composting facilities.

Galactosylated chitosan-graft-dextran as hepatocyte-targeting DNA carrier

Lactobionic acid bearing galactose group was coupled with chitosan for liver specificity, and dextran was grafted to galactosylated chitosan (GC) for stability in water. Compared to the GC/DNA complex, the stability of the galactosylated chitosan-graft-dextran (GCD)/DNA complex could be enhanced. The particle size of the GCD/DNA complexes decreased as the charge ratio of GCD to DNA increased. Conformational change of DNA did not occur after complex formation with GCD compared with the conformation of DNA itself. The GCD/DNA complexes were only transfected into Chang liver cells and that of Hep G2 having asialoglycoprotein receptors (ASGR), indicative of specific interaction of ASGRs on cells and galactose ligands on chitosan.

Proteolytic stability of recombinant human serum albumin secreted in the yeast Saccharomyces cerevisiae

In order to direct the persistent expression of recombinant human serum albumin (HSA) from the GAL10 promoter in the yeast Saccharomyces cerevisiae, we carried out periodic feeding of galactose during shake-flask cultures. Unexpectedly, the recombinant protein secreted was observed to undergo rapid degradation, which was apparently accelerated by carbon-source feeding. The extracellular degradation of HSA occurred even in the strain deficient in the major vacuolar proteases PrA and PrB, and in the strain lacking the acidic protease Yap3p (involved in the generation of HSA-truncated fragments). Interestingly, the degradation correlated closely with the acidification of extracellular pH and thus was significantly overcome either by buffering the culture medium above pH 5.0 or by adding amino acid-rich supplements to the culture medium, which could prevent the acidification of medium pH during cultivation. Addition of arginine or ammonium salt also substantially minimized the degradation of HSA, even without buffering. The extracellular degradation activity was not detected in the cell-free culture supernatant but was found to be associated with intact cells. The results of the present study strongly suggest that the HSA secreted in S. cerevisiae is highly susceptible to the pH-dependent proteolysis mediated by cell-bound protease(s) whose activity and expression are greatly affected by the composition of the medium.

Presence of circulating antibodies to a disease-specific antigen on cultured human dermal microvascular endothelial cells in patients with Behçet's disease

Behçet's disease is a chronic, multisystem disorder characterized by a recurrent inflammatory reaction. Antiendothelial cell antibodies have been detected in the serum from patients with autoimmune diseases with presenting vasculitis and it is assumed that they can induce damage to the endothelial cells. In this study, we detected antiendothelial cell antibodies in the serum from patients with Behçet's disease using an enzyme-linked immunosorbent assay, electrophoresis and immunoblotting. The cytolysis of human dermal microvascular endothelial cells (HDMEC) was measured using a cytotoxicity assay. The serum from 37.4% of Behçet's disease patients showed IgM antibodies against unstimulated HDMEC while the serum from 18.4% of patients showed an increase in IgM antibody titer after IFN-gamma pretreatment. The frequency of vasculitis was higher in the IgM-positive Behçet's disease patients than in the IgM-negative patients. In Western blotting, IgM-positive Behçet's disease serum reacted with the 44 kDa HDMEC surface antigen, whereas IgM-positive systemic lupus erythematosus serum reacted with the 81 kDa HDMEC surface antigen. The reactivity to the 44 kDa protein band was also observed in cultured human umbilical vein endothelial cells but not in fibroblasts, A431 cells or SK-MEL-2 cells. Serum from Behçet's disease patients incubated with human complement or mononuclear cells produced no significant lysis of HDMEC, and cultured HDMEC were resistant to antibody-dependent cell-mediated cytotoxicity. The results suggest that antibodies against antigens on the surface of endothelial cells may play a role in inducing vasculitis in Behçet's disease, not through a direct toxic effect of an antiendothelial cell antibody but by an indirect effect involving the activation of endothelial cells to produce cytokines.

A dominant selection system designed for copy-number-controlled gene integration in Hansenula polymorpha DL-1

To facilitate the selection of multiple gene integrants in Hansenula polymorpha, a rapid and copy-number-controlled selection system was developed using a vector containing a telomeric autonomous replication sequence and the bacterial aminoglycoside 3-phosphotransferase (APH) gene. Direct use of the unmodified APH gene as a dominant selectable marker resulted in the extremely slow growth of transformants and the frequent selection of spontaneous resistance. For the proper performance of the APH gene, a set of deleted glyceraldehyde-3-phosphate dehydrogenase (GAPDH) promoters of H. polymorpha were fused to the APH gene. The fusion construct with the 578-bp GAPDH promoter conferred G418 resistance sufficient to allow rapid growth of transformants, and thus facilitated the selection of transformants with up to 15 tandem copies of the vector. To increase further the integration copy number within the gene-dose-dependent range, the GAPDH promoter was serially deleted down to the -61 nucleotide. With this weak expression cassette, the integration copy number could easily be controlled between 1 and 50. Tandemly integrated copies of plasmids near the end of the chromosome were mitotically stable over 150 generations. The dosage-dependent selection system of this study would provide a powerful tool for the development of H. polymorpha as an industrial strain to produce recombinant proteins.

Vectors for rapid selection of integrants with different plasmid copy numbers in the yeast Hansenula polymorpha DL1

Plasmids with different selectable markers were constructed and used to transform the Hansenula polymorpha strain DL1. It was shown that, depending on the host mutant strain, the use of these plasmids enables rapid selection of transformants with plasmids integrated in low (1-2), moderate (6-9) or high (up to 100) copy numbers. The vectors and mutant described are potentially useful for the construction of efficient producers of heterologous proteins in H. polymorpha.

A family of telomere-associated autonomously replicating sequences and their functions in targeted recombination in Hansenula polymorpha DL-1

A family of multiple autonomously replicating sequences (ARSs) which are located at several chromosomal ends of Hansenula polymorpha DL-1 has been identified and characterized. Genomic Southern blotting with an ARS, HARS36, originating from the end of a chromosome, as a probe showed several homologues in the genome of H. polymorpha. Nucleotide sequences of the three fragments obtained by a selective cloning for chromosomal ends were nearly identical to that of HARS36. All three fragments harbored an ARS motif and ended with 18 to 23 identical repetitions of 5'-GGGTGGCG-3' which resemble the telomeric repeat sequence in other eukaryotes. Transformation of H. polymorpha with nonlinearized plasmids containing the newly obtained telomeric ARSs almost exclusively resulted in the targeted integration of a single copy or multiple tandem copies of the plasmid into the chromosomes. The sensitivity to exonuclease Bal31 digestion of the common DNA fragment in all integrants confirmed the telomeric origin of HARS36 homologues, suggesting that several chromosomal ends, if not all of them, consisted of the same ARS motif and highly conserved sequences observed in HARS36. Even though the frequencies of targeted recombination were varied among the ends of the chromosomes, the overall frequency was over 96%. The results suggested that the integration of the plasmids containing telemeric ARSs occurred largely through homologous recombination at the telomeric repeats, which serve as high-frequency recombination targets.