Giant X-Ray Circular Dichroism in a Time-Reversal Invariant Antiferromagnet

X-ray circular dichroism, arising from the contrast in X-ray absorption between opposite photon helicities, serves as a spectroscopic tool to measure the magnetization of ferromagnetic materials and identify the handedness of chiral crystals. Antiferromagnets with crystallographic chirality typically lack X-ray magnetic circular dichroism because of time-reversal symmetry, yet exhibit weak X-ray natural circular dichroism. Here, the observation of giant natural circular dichroism in the Ni L3-edge X-ray absorption of Ni3TeO6 is reported, a polar and chiral antiferromagnet with effective time-reversal symmetry. To unravel this intriguing phenomenon, a phenomenological model is proposed that classifies the movement of photons in a chiral crystal within the same symmetry class as that of a magnetic field. The coupling of X-ray polarization with the induced magnetization yields giant X-ray natural circular dichroism, revealing typical ferromagnetic behaviors allowed by the symmetry in an antiferromagnet, i.e., the altermagnetism of Ni3TeO6. The findings provide evidence for the interplay between magnetism and crystal chirality in natural optical activity. Additionally, the first example of a new class of magnetic materials exhibiting circular dichroism is established with time-reversal symmetry.

Effect of Ag-Decorated BiVO4 on Photoelectrochemical Water Splitting: An X-ray Absorption Spectroscopic Investigation

Bismuth vanadate (BiVO₄) has attracted substantial attention on account of its usefulness in producing hydrogen by photoelectrochemical (PEC) water splitting. The exploitation of BiVO₄ for this purpose is yet limited by severe charge recombination in the bulk of BiVO₄, which is caused by the short diffusion length of the photoexcited charge carriers and inefficient charge separation. Enormous effort has been made to improve the photocurrent density and solar-to-hydrogen conversion efficiency of BiVO₄. This study demonstrates that modulating the composition of the electrode and the electronic configuration of BiVO₄ by decoration with silver nanoparticles (Ag NPs) is effective in not only enhancing the charge carrier concentration but also suppressing charge recombination in the solar water splitting process. Decoration with a small number of Ag NPs significantly enhances the photocurrent density of BiVO₄ to an extent that increases with the concentration of the Ag NPs. At 0.5% Ag NPs, the photocurrent density approaches 4.1 mA cm^-2 at 1.23 V versus a reversible hydrogen electrode (RHE) under solar simulated light illumination; this value is much higher than the 2.3 mA cm^-2 of pure BiVO₄ under the same conditions. X-ray absorption spectroscopy (XAS) is utilized to investigate the electronic structure of pure BiVO₄ and its modification by decoration with Ag NPs. Analytical results indicate that increased distortion of the VO₄ tetrahedra alters the V 3d-O 2p hybridized states. Additionally, as the Ag concentration increases, the oxygen vacancy defects that act as recombination centers in BiVO₄ are reduced. In situ XAS, which is conducted under dark and solar illumination conditions, reveals that the significantly enhanced PEC performance is attributable to the synergy of modulated atomic/electronic structures and the localized surface plasmon resonance effect of the Ag nanoparticles.

[Measurement of morphological features of Oncomelania hupensis shells in Yunnan Province]

OBJECTIVE

To investigate the morphological variation of Oncomelania hupensis shells in Yunnan Province, so as to provide insights into the understanding of O. hupensis genetic evolution and control.

METHODS

According to the O. hupensis density, geographical location, altitude, water system and environmental type, 12 administrative villages were sampled from 10 schistosomiasis-endemic counties (districts) in 3 prefectures (cities) of Yunnan Province as snail collection sites. From December 2021 to January 2022, about 200 snails were collected from each collection site, among which thirty adult snails (6 to 7 spirals) were randomly selected from each site, and the 11 morphological indexes of snail shells were measured and subjected to cluster analysis and principal component analysis.

RESULTS

Of O. hupensis snails from 12 localities of Yunnan Province, the longest shell (7.33 mm) was detected in snails from Yongle Village, Eryuan County, with the shortest (4.68 mm) in Dongyuan Village, Gucheng District, and the largest angle of apex (59.47°) was measured in snails from Caizhuang Village, Midu County, with the smallest (41.40°) in Qiandian Village, Eryuan County. The mean coefficient of variation was 9.075% among O. hupensis snails from 12 localities of Yunnan Province, with the largest coefficient of variation seen in the thickness of the labra brim (29.809%). Among O. hupensis snails from 12 localities of Yunnan Province, the mean Euclidean distance was 2.26, with the shortest Euclidean distance seen between O. hupensis snails from Qiandian Village of Eryuan County and Wuxing Village of Dali City (0.26), and the largest found between O. hupensis snails from Caizhuang Village of Midu County and Cangling Village of Chuxiong County (8.17). Cluster analysis and principal component analysis classified O. hupensis snails from 12 localities of Yunnan Province into three categories, including the O. hupensis snail samples from Caizhuang Village of Midu County, O. hupensis snail samples from Cangling Village of Chuxiong County, and O. hupensis snail samples from Qiandian Village of Eryuan County, Wuxing Village of Dali City, Yangwu Village of Yongsheng County, Xiaoqiao Village of Xiangyun County, Yongle Village of Eryuan County, Xiaocen Village of Dali City, Anding Village of Nanjian County, Dongyuan Village of Gucheng District, Lianyi Village of Heqing County, and Dianzhong Village of Weishan County. The variations in these three categories of snail samples were mainly measured in the principal component 2 related to the angle of apex and the thickness of the labra brim.

CONCLUSIONS

The variations in the Euclidean distance and morphological features of shells of O. hupensis from 12 localities of Yunnan Province gradually rise with the decrease in the latitude of the collection sites. The angle of apex is an indicator for the growth of O. hupensis whorl.

Bandgap Shrinkage and Charge Transfer in 2D Layered SnS2 Doped with V for Photocatalytic Efficiency Improvement

Effects of electronic and atomic structures of V-doped 2D layered SnS₂ are studied using X-ray spectroscopy for the development of photocatalytic/photovoltaic applications. Extended X-ray absorption fine structure measurements at V K-edge reveal the presence of VO and VS bonds which form the intercalation of tetrahedral OVS sites in the van der Waals (vdW) gap of SnS₂ layers. X-ray absorption near-edge structure (XANES) reveals not only valence state of V dopant in SnS₂ is ≈4⁺ but also the charge transfer (CT) from V to ligands, supported by V L_α,β resonant inelastic X-ray scattering. These results suggest V doping produces extra interlayer covalent interactions and additional conducting channels, which increase the electronic conductivity and CT. This gives rapid transport of photo-excited electrons and effective carrier separation in layered SnS₂ . Additionally, valence-band photoemission spectra and S K-edge XANES indicate that the density of states near/at valence-band maximum is shifted to lower binding energy in V-doped SnS₂ compare to pristine SnS₂ and exhibits band gap shrinkage. These findings support first-principles density functional theory calculations of the interstitially tetrahedral OVS site intercalated in the vdW gap, highlighting the CT from V to ligands in V-doped SnS₂ .

[Analysis on the imported Coronavirus Disease 2019 related cluster epidemic in rural areas of Chengdu]

An epidemiological investigation was carried out on a local cluster of outbreak caused by imported cases of Coronavirus Disease 2019 (COVID-19) in rural areas of Chengdu in December 2020, to find out the source of infection and the chain of transmission. According to Prevention and Control Protocol for COVID-19 (Version 7), field epidemiological investigation was adopted, combined with big data technology, video image investigation, gene sequencing and other methods to carry out investigation into COVID-19 cases and infections source tracing, analyze the epidemiological association, and map the chain of transmission. From December 7 to 17, 2020, 13 local COVID-19 confirmed cases and 1 asymptomatic case were diagnosed in Chengdu, of which 12 cases (85.71%) had a history of residence and activity in the village courtyard of Taiping (TP), Pidu (P) District, Chengdu. From November 8, 2020 to November 28, 2020, a group of inbound people form Nepal were transferred to the designated entry personnel quarantine hotel of P District which was adjacent to the TP village. During quarantine, there were 5 cases who tested positive for COVID-19. Through gene sequencing alignment, genes of local cases and Nepalese imported cases from the same period are homologous, all belong to the lineage of L2.2.3 (B.1.36 according to Pangolin lineage typing method). According to the results of field epidemiological investigation and gene sequencing analysis, the index case was most likely infected by contact with household waste of quarantine site. Under the situation of normalization prevention and control of COVID-19, sentinel monitoring of fever clinics in primary medical institutions is the key to early detection of the epidemic. The multi-department joint epidemiological investigation and the application of gene technology are the core links of the investigation and traceability of modern infectious diseases. The allocation of public health resources in rural areas needs to be strengthened. We need to improve the capacity for early surveillance and early warning of the epidemic in rural areas.

Role of Interfacial Defects in Photoelectrochemical Properties of BiVO4 Coated on ZnO Nanodendrites: X-ray Spectroscopic and Microscopic Investigation

Synchrotron-based X-ray spectroscopic and microscopic techniques are used to identify the origin of enhancement of the photoelectrochemical (PEC) properties of BiVO₄ (BVO) that is coated on ZnO nanodendrites (hereafter referred to as BVO/ZnO). The atomic and electronic structures of core-shell BVO/ZnO nanodendrites have been well-characterized, and the heterojunction has been determined to favor the migration of charge carriers under the PEC condition. The variation of charge density between ZnO and BVO in core-shell BVO/ZnO nanodendrites with many unpaired O 2p-derived states at the interface forms interfacial oxygen defects and yields a band gap of approximately 2.6 eV in BVO/ZnO nanocomposites. Atomic structural distortions at the interface of BVO/ZnO nanodendrites, which support the fact that there are many interfacial oxygen defects, affect the O 2p-V 3d hybridization and reduce the crystal field energy 10Dq ∼2.1 eV. Such an interfacial atomic/electronic structure and band gap modulation increase the efficiency of absorption of solar light and electron-hole separation. This study provides evidence that the interfacial oxygen defects act as a trapping center and are critical for the charge transfer, retarding electron-hole recombination, and high absorption of visible light, which can result in favorable PEC properties of a nanostructured core-shell BVO/ZnO heterojunction. Insights into the local atomic and electronic structures of the BVO/ZnO heterojunction support the fabrication of semiconductor heterojunctions with optimal compositions and an optimal interface, which are sought to maximize solar light utilization and the transportation of charge carriers for PEC water splitting and related applications.

[Clinical characteristics, diagnosis and treatment of human babesiosis: a review]

Babesiosis is an important tick-transmitted zoonosis caused by hematotropic parasites of the genus Babesia, zoonosis disease, which is widely distributed across the world. There are 12 species of Babesia causing human diseases, including B. microti, B. divergens, B. venatorum and B. duncani. The clinical symptoms of human Babesia infections mainly include fever, headache, chills, myalgia and fatigue, and severe infections may cause death. The diagnosis of babesiosis mainly depends on laboratory testing combined with clinical manifestations and epidemiological surveys, and the diagnostic techniques mainly include microscopic examinations of the blood smears, serological tests and molecular biological assays. Currently, azithromycin-atova-quone or clindamycin-quinine combinations are common treatments for babesiosis. This review summarizes the clinical features following human infections with various species of Babesia, the diagnostic techniques and diagnostic criteria of babesiosis and the currently available treatments for babesiosis.

[Assessment of schistosomiasis transmission risk in Nanjian County of Yunnan Province in 2019]

OBJECTIVE

To assess the schistosomiasis transmission risk in Nanjing County, so as to provide the scientific evidence for the development of the schistosomiasis control strategy and consolidation of the control achievements.

METHODS

On May 2019, the Deqiu Village in Deqiu Town and Baiyun Village in Nanjing Town of Yunnan Province, where schistosomiasis were historically relatively highly endemic, were selected to assess the risk of transmission of schistosomiasis by means of a retrospective review of the data pertaining to the historical endemic situation and schistosomiasis control, combined with a cross-sectional survey of snail and wild feces distribution.

RESULTS

During the period between 2017 and 2018, the mean sero-prevalence rates of Schistosoma japonicum infections were 6.76% (202/2 990) and 2.86% (142/4 971) in humans and 0 (0/1 160) and 10.65% (31/291) in bovines in Deqiu and Baiyun villages of Nanjian County, respectively; however, no egg-positives were identified; in addition, there were 21.06 hm² snail habitats found, but no S. japonicum infections were detected in snails. In 2019, there was 6.17 hm² snail habitats detected, with 2.17% (245/11 298) occurrence of frames with snails and a 0.06 snails/0.1 m² density of living snails; however, no positives for nucleic acid detection were seen in snails; among the 136 wild fecal samples captures from 23 settings, no S. japonicum infections were identified.

CONCLUSIONS

The risk of schistosomiasis transmission remains at a low level in Nanjian County; however, the factors affecting the transmission of schistosomiasis have not been completed eliminated. The integrated schistosomiasis control strategy with an emphasis on the control of the source of S. japonicum infections requires to be reinforced to consolidate the control achievements.

[Molecular identification of Tricula spp. and the parasitized trematode cercariae in schistosomiasis-endemic areas of Yunnan Province]

OBJECTIVE

To characterize a species of the genus Tricula and parasitized trematodes in schistosomiasis-endemic areas of Yunnan Province using a molecular analysis, so as to understand their taxonomic positions.

METHODS

Tricula spp. and Oncomelania snails were collected from Xiangyun County, Yunnan Province, and cercaria parasitizing snails were observed using crushing followed by microscopy. Cercaria parasitizing Tricula snails at various morphologies were sampled using a shedding method. Genomic DNA was extracted from snail soft tissues and cercariae, and the 16S rRNA, COI, 28S rDNA genes in snails and the ND1 and 28S rDNA genes in cercariae were amplified using a PCR assay and sequenced. The species of Tricula snails and their parasitized trematodes was characterized using sequence alignment and phylogenetic analysis.

RESULTS

Among 382 Tricula snails detected, there were three types of trematode cercariae found, including the non-forked (20.94%, 80/382), double-forked (3.40%, 13/382) and swallow shapes (7.07%, 27/382). Sequence and phylogenetic analyses showed that the 16S rRNA, COI and 28S rDNA gene sequences of this species of Tricula had high homology to those in Delavaya dianchiensis, and were clustered in a branch. Sequencing analysis of the ND1 and 28S rDNA genes revealed that the non-forked cercariae belonged to the family Pleu- rogenidae, the swallow-shaped cercariae belonged to the family Opecoelidae, and the double-forked cercariae belonged to another species of the genus Schistosoma that was different from S. sinensium and S. ovuncatum.

CONCLUSIONS

The species and taxonomy of Triculla spp. and their parasitized trematodes are preliminarily determined in schistosomiasis-endemic areas of Yunnan Province; however, further studies are required to investigate the more definite taxonomy and pathogenicity.

Anomalous boron isotope effects on electronic structure and lattice dynamics of CuB2O4

Copper metaborate had a unique crystal structure and exhibited noteworthy magnetic phase transitions at 21 and 10 K.

The effect of orbital-lattice coupling on the electrical resistivity of YBaCuFeO5 investigated by X-ray absorption

Temperature-dependent X-ray absorption near-edge structures, X-ray linear dichroism (XLD) and extended X-ray absorption fine structure (EXAFS) spectroscopic techniques were used to investigate the valence state, preferred orbital and local atomic structure that significantly affect the electrical and magnetic properties of a single crystal of YBaCuFeO5 (YBCFO). An onset of increase of resistivity at ~180 K, followed by a rapid increase at/below 125 K, is observed. An antiferromagnetic (AFM)-like transition is close to the temperature at which the resistivity starts to increase in the ab-plane and is also observed with strong anisotropy between the ab-plane and the c-axis. The XLD spectra at the Fe L3,2-edge revealed a change in Fe 3d eg holes from the preferential [Formula: see text] orbital at high temperature (300-150 K) to the [Formula: see text] orbital at/below 125 K. The analysis of the Fe K-edge EXAFS data of YBCFO further revealed an unusual increase in the Debye-Waller factor of the nearest-neighbor Fe-O bond length at/below 125 K, suggesting phonon-softening behavior, resulting in the breaking of lattice symmetry, particularly in the ab-plane of Fe-related square pyramids. These findings demonstrate a close correlation between electrical resistivity and coupling of the preferred Fe 3d orbital with lattice distortion of a single crystal of YBCFO.

Spin-charge-lattice coupling in YBaCuFeO5: Optical properties and first-principles calculations

We combined spectroscopic ellipsometry, Raman scattering spectroscopy, and first-principles calculations to explore the optical properties of YBaCuFeO5 single crystals. Measuring the optical absorption spectrum of YBaCuFeO5 at room temperature revealed a direct optical band gap at approximately 1.41 eV and five bands near 1.69, 2.47, 3.16, 4.26, and 5.54 eV. Based on first-principles calculations, the observed optical excitations were appropriately assigned. Analysis of the temperature dependence of the band gap indicated anomalies in antiferromagnetic phase transition at 455 and 175 K. Additionally, a hardening in the frequency of the Eg phonon mode was observed at 175 K. The value of the spin-phonon coupling constant was 15.7 mRy/Å2. These results suggest a complex nature of spin-charge-lattice interactions in YBaCuFeO5.

Autoantibody against integrin αv β3 contributes to thrombocytopenia by blocking the migration and adhesion of megakaryocytes

Essentials The pathogenesis of immune thrombocytopenia (ITP) has not been fully clarified. We analyzed the role of anti-αvβ3 autoantibody in the pathogenesis of ITP in patients. Anti-αvβ3 autoantibody impeded megakaryocyte migration and adhesion to the vascular niche. Anti-αv β3 autoantibody potentially contributes to the pathogenesis of refractory ITP.

SUMMARY

Background The pathogenesis of immune thrombocytopenia (ITP) has not been fully clarified. Anti-αvβ3 integrin autoantibody is detected in chronic ITP patients, but its contribution to ITP is still unclear. Objectives To clarify the potential role of anti-αvβ3 integrin autoantibody in chronic ITP and the related mechanism. Methods Relationship between levels of anti-αvβ3 autoantibody and platelets in chronic ITP patients was evaluated. The influence of anti-αvβ3 antibody on megakaryocyte (MK) survival, differentiation, migration and adhesion was assessed, and the associated signal pathways were investigated. Platelet recovery and MKs' distribution were observed in an ITP mouse model pretreated with different antibodies. Result In this study, we showed that the anti-αvβ3 autoantibody usually coexists with anti-αIIbβ3 autoantibody in chronic ITP patients, and patients with both autoantibodies have lower platelets. In in vitro studies, we showed that the anti-αvβ3 antibody had no significant effect on the survival and proliferation of MKs, whereas it decreased formations of proplatelet significantly. Anti-αvβ3 antibody impeded stromal cell derived facor-1 alpha (SDF-1α)- mediated migration and inhibited the phosphorylation of protein kinase B. Anti-αvβ3 antibody significantly inhibited MKs' adhesion to endothelial cells and Fibrogen. The phosphorylation of focal adhesion kinase and proto-oncogene tyrosine-protein kinase Src induced by adhesion was inhibited when MKs were pretreated with anti-αvβ3 antibody. In in vivo studies, we showed that injection with anti-αv antibody delayed platelet recovery in a mouse model of ITP. Conclusions These findings demonstrate that the autoantibody against integrin αv β3 may aggravate thrombocytopenia in ITP patients by impeding MK migration and adhesion to the vascular niche, which provides new insights into the pathogenesis of ITP.

Magnetic ordering and dielectric relaxation in the double perovskite YBaCuFeO5

Using magnetization, dielectric constant, and neutron diffraction measurements on a high quality single crystal of YBaCuFeO₅ (YBCFO), we demonstrate that the crystal shows two antiferromagnetic transitions at [Formula: see text] K and [Formula: see text] K, and displays a giant dielectric constant with a characteristic of the dielectric relaxation at T _N2. It does not show the evidence of the electric polarization for the crystal used for this study. The transition at T _N1 corresponds with a paramagnetic to antiferromagnetic transition with a magnetic propagation vector doubling the unit cell along three crystallographic axes. Upon cooling, at T _N2, the commensurate spin ordering transforms to a spiral magnetic structure with a propagation vector of ([Formula: see text] [Formula: see text] [Formula: see text]), where [Formula: see text], [Formula: see text], and [Formula: see text] are odd, and the incommensurability δ is temperature dependent. Around the transition boundary at T _N2, both commensurate and incommensurate spin ordering coexist.

X-ray multi-beam resonant diffraction analysis of crystal symmetry for layered perovskite YBaCuFeO5

The open question of crystal symmetry for YBaCuFeO5, still under debate, is resolved by using diffraction anomalous fine structure and resonant multi-beam X-ray diffraction at the Fe and Cu K edges. The different asymmetric intensity distributions observed at 7, 7.1305 and 8.9945 keV give direct evidence that the space group of YBaCuFeO5 should be P4/mmm with the distance between Cu and apical O atoms longer than that between Fe and O atoms. This approach provides a direct way to resolve detailed structural symmetry which is indeterminate in conventional Bragg diffraction.

[Study on the expression of T, B lymphocyte antigen and platelet antibodies in patients with platelet transfusion refractoriness]

目的

探讨T、B淋巴细胞，血小板膜糖蛋白和血小板抗体在血小板输注无效中作用。

方法

选择41例临床确诊血小板输注无效患者为研究对象，以27例血小板输注有效患者为对照组，采用流式细胞术检测两组患者外周血细胞毒性T淋巴细胞（CD3 ⁺CD4⁻CD8⁺）、辅助性T淋巴细胞（CD3 ⁺ CD4⁺CD8⁻）、B淋巴细胞（CD19⁺）比例和血小板膜糖蛋白CD41а、CD61的表达，采用固相凝集法检测两组患者血清中的血小板抗体。

结果

与对照组比较，血小板输注无效组患者：①辅助性T细胞比例明显下降（36.60%对48.53%），细胞毒性T细胞比例显著增高（53.26%对44.02%），二者比值下降（0.85对1.31），差异均有统计学意义（P值均<0.05）；②B淋巴细胞比例差异无统计学意义（3.02%对2.85%，P=0.901）；③CD41а阳性细胞率[（88.10±12.75）%对（51.69±24.45）%，P=0.001]和CD61阳性细胞率[（88.36±12.31）%对（51.83±24.48）%，P<0.001]均显著升高；④血小板抗体阳性率显著增高（85.37%对14.82%，P<0.05）。

结论

细胞毒性T淋巴细胞的激活、辅助性T细胞的抑制、血小板膜糖蛋白CD41а和CD61的表达以及血小板抗体的产生均在血小板输注无效的发生过程中发挥重要作用。

Scaling of spin Hall angle in 3d, 4d, and 5d metals from Y3Fe5O12/metal spin pumping

We have investigated spin pumping from Y3Fe5O12 thin films into Cu, Ag, Ta, W, Pt, and Au with varying spin-orbit coupling strengths. From measurements of Gilbert damping enhancement and inverse spin Hall signals spanning 3 orders of magnitude, we determine the spin Hall angles and interfacial spin mixing conductances for the six metals. The spin Hall angles largely vary as Z(4) (Z: atomic number), corroborating the role of spin-orbit coupling. Amongst the four 5d metals, the variation of the spin Hall angle is dominated by the sensitivity of the d-orbital moment to the d-electron count, confirming theoretical predictions.

Probing the spin pumping mechanism: exchange coupling with exponential decay in Y3Fe5O12/barrier/Pt heterostructures

It is widely believed that the mechanism for spin pumping in ferromagnet-nonmagnet bilayers is the exchange interaction between the ferromagnet and nonmagnetic material. We observe 1000-fold exponential decay of spin pumping from thin Y3Fe5O12 films to Pt across insulating barriers, from which exponential decay lengths of 0.16, 0.19, and 0.23 nm are extracted for oxide barriers having band gaps of 4.91, 3.40, and 2.36 eV, respectively. This archetypal signature of quantum tunneling through a barrier underscores the importance of exchange coupling for spin pumping and reveals its dependence on the characteristics of the barrier material.

Using autocloning effects to develop broad-bandwidth, omnidirectional antireflection structures for silicon solar cells

In this study, we used the autocloning effect on pyramid structures to develop broad-bandwidth, omnidirectional antireflection structures for silicon solar cells. The angular dependence of reflectance on several pyramid structures was systematically investigated. The deposition of three-layer autocloned films reduced the refractive index gap between air and silicon, resulting in an increase in the amount of transmitted light and a decrease in the total light escaping. The average reflectance decreased dramatically to ca. 2-3% at incident angles from 0 to 60° for both sub-wavelength- and micrometer-scale pyramid structures. The measured reflectance of the autocloned structure was less than 4% in the wavelength range from 400 to 1000 nm for incident angles from 0 to 60°. Therefore, the autocloning technique, combined with optical thin films and optical gradient structures, is a practical and compatible method for the fabrication of broad-bandwidth, omnidirectional antireflection structures on silicon solar cells.

The modulated structure and ferromagnetic insulating state in a nine-layer BaRuO(3)

We report the observation of a modulated structure and a ferromagnetic insulating state in a high quality single crystal of a nine-layer BaRuO(3). Using x-ray scattering, the modulated satellites were observed to double the unit cell along the c-axis at low temperature. The ferromagnetic insulating state is confirmed by magnetic and resistivity measurements. Analyzing the peak profiles from the modulation and host structure respectively, showed a lattice distortion at T∼55 K. These findings elucidate the intimate relationship between ferromagnetism and lattice distortion in a nine-layer BaRuO(3).

Growth and characterization of V-shaped IrO(2) nanowedges via metal-organic vapor deposition

We report in detail the synthesis and characterization of V-shaped IrO(2) nanowedges (NWs) with an angle of 110° between the two arms. The NWs were grown on top of rutile (R) phase TiO(2) nanorods (NRs) sitting on a sapphire (SA)(100) substrate via metal-organic chemical vapor deposition (MOCVD) by using (C(6)H(7))(C(8)H(12))Ir and titanium-tetraisopropoxide (TTIP, Ti[OCH(CH(3))(2)](4)) as the source reagents. The surface morphology, structural, and spectroscopic properties of the as-deposited nanocrystals (NCs) were characterized by field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), micro-Raman spectroscopy, transmission electron microscopy (TEM), and selected-area electron diffractometry (SAED). The FESEM images and XRD patterns indicated growth of V-shaped IrO(2)(101) NWs on top of R-TiO(2) NRs. The Raman spectrum showed the nanosize induced redshift and peak broadening of the IrO(2) and rutile phase of TiO(2) signatures with respect to that of the bulk counterparts. TEM and SAED characterizations of IrO(2) NCs showed that the nanowedges were crystalline IrO(2) with a twin plane of (101) and twin direction of [Formula: see text] at the V-junction. The probable mechanisms for the formation of well-aligned IrO(2) NWs are discussed.

X-ray multiple-wave coherent interaction in a quasi-two-dimensional material NbSe2-2H

The first observation of the X-ray multiple-wave interaction in an incommensurate charge-density-wave (CDW) modulated structure at low temperatures is reported for an example of a quasi-two-dimensional material, NbSe(2)-2H. Via the coherent interaction between the X-ray waves propagating in the CDW-modulated structure and the host structure, the phase-dependent intensity variations of a CDW reflection were detected. In accord with a centrosymmetric structure, the phases of the structure-factor triplets of two CDW reflections and a Bragg reflection of the host structure were determined to be either 0 or 180 degrees, and not to vary with temperature. Relative phase differences of the two CDW reflections are also deduced.

Critical fluctuations and quenched disordered two-dimensional charge stripes in La(5/3)Sr(1/3)NiO4

Using high-resolution x-ray scattering, we have demonstrated the existence of quenched disordered charge stripes in a single crystal of La (5/3)Sr (1/3)NiO (4) at low temperatures. Above the second-order transition critical scattering was observed due to fluctuations into the charge stripe phase. The charge stripes are shown to be two dimensional in nature both by measurements of their correlation lengths (xi(a) approximately 185 A, xi(b) = 400 A, and xi(c) approximately 25 A) and by the critical exponents of the charge strip transition. The charge stripe ordering did not develop long-range order even at low temperatures, indicating that the charge stripes are disordered and that the length scale of the disorder is quenched.