Ptychographic Nanoscale Imaging of the Magnetoelectric Coupling in Freestanding BiFeO3.

Understanding the magnetic and ferroelectric ordering of magnetoelectric multiferroic materials at the nanoscale necessitates a versatile imaging method with high spatial resolution. Here, soft X-ray ptychography is employed to simultaneously image the ferroelectric and antiferromagnetic domains in an 80 nm thin freestanding film of the room-temperature multiferroic BiFeO3 (BFO). The antiferromagnetic spin cycloid of period 64 nm is resolved by reconstructing the corresponding resonant elastic X-ray scattering in real space and visualized together with mosaic-like ferroelectric domains in a linear dichroic contrast image at the Fe L3 edge. The measurements reveal a near perfect coupling between the antiferromagnetic and ferroelectric ordering by which the propagation direction of the spin cycloid is locked orthogonally to the ferroelectric polarization. In addition, the study evinces both a preference for in-plane propagation of the spin cycloid and changes of the ferroelectric polarization by 71° between multiferroic domains in the epitaxial strain-free, freestanding BFO film. The results provide a direct visualization of the strong magnetoelectric coupling in BFO and of its fine multiferroic domain structure, emphasizing the potential of ptychographic imaging for the study of multiferroics and non-collinear magnetic materials with soft X-rays.

Revealing Resistive Switching Mechanism in CaFeOx Perovskite System with Electroforming-Free and Reset Voltage-Controlled Multilevel Resistance Characteristics.

Recently, perovskite (PV) oxides with ABO3 structures have attracted considerable interest from scientists owing to their functionality. In this study, CaFeOx is introduced to reveal the resistive switching properties and mechanism of oxygen vacancy transition in PV and brownmillerite (BM) structures. BM-CaFeO2.5 is grown on an Nb-STO conductive substrate epitaxially. CaFeOx exhibits excellent endurance and reliability. In addition, the CaFeOx also demonstrates an electroforming-free characteristic and multilevel resistance properties. To construct the switching mechanism, high-resolution transmission electron microscopy is used to observe the topotactic phase change in CaFeOx . In addition, scanning TEM and electron energy loss spectroscopy show the structural evolution and valence state variation of CaFeOx after the switching behavior. This study not only reveals the switching mechanism of CaFeOx , but also provides a PV oxide option for the dielectric material in resistive random-access memory (RRAM) devices.

Twisted oxide lateral homostructures with conjunction tunability.

Epitaxial growth is of significant importance over the past decades, given it has been the key process of modern technology for delivering high-quality thin films. For conventional heteroepitaxy, the selection of proper single crystal substrates not only facilitates the integration of different materials but also fulfills interface and strain engineering upon a wide spectrum of functionalities. Nevertheless, the lattice structure, regularity and crystalline orientation are determined once a specific substrate is chosen. Here, we reveal the growth of twisted oxide lateral homostructure with controllable in-plane conjunctions. The twisted lateral homostructures with atomically sharp interfaces can be composed of epitaxial "blocks" with different crystalline orientations, ferroic orders and phases. We further demonstrate that this approach is universal for fabricating various complex systems, in which the unconventional physical properties can be artificially manipulated. Our results establish an efficient pathway towards twisted lateral homostructures, adding additional degrees of freedom to design epitaxial films.

Presence of Delocalized Ti 3d Electrons in Ultrathin Single-Crystal SrTiO3.

Strontium titanate (STO), with a wide spectrum of emergent properties such as ferroelectricity and superconductivity, has received significant attention in the community of strongly correlated materials. In the strain-free STO film grown on the SrRuO3 buffer layer, the existing polar nanoregions can facilitate room-temperature ferroelectricity when the STO film thickness approaches 10 nm. Here we show that around this thickness scale, the freestanding STO films without the influence of a substrate show the tetragonal structure at room temperature, contrasting with the cubic structure seen in bulk form. The spectroscopic measurements reveal the modified Ti-O orbital hybridization that causes the Ti ion to deviate from its nominal 4+ valency (3d0 configuration) with excess delocalized 3d electrons. Additionally, the Ti ion in TiO6 octahedron exhibits an off-center displacement. The inherent symmetry lowering in ultrathin freestanding films offers an alternative way to achieve tunable electronic structures that are of paramount importance for future technological applications.

Spectroscopic characterization of electronic structures of ultra-thin single crystal La0.7Sr0.3MnO3.

We have successfully fabricated high quality single crystalline La0.7Sr0.3MnO3 (LSMO) film in the freestanding form that can be transferred onto silicon wafer and copper mesh support. Using soft x-ray absorption (XAS) and resonant inelastic x-ray scattering (RIXS) spectroscopy in transmission and reflection geometries, we demonstrate that the x-ray emission from Mn 3s-2p core-to-core transition (3sPFY) seen in the RIXS maps can represent the bulk-like absorption signal with minimal self-absorption effect around the Mn L3-edge. Similar measurements were also performed on a reference LSMO film grown on the SrTiO3 substrate and the agreement between measurements substantiates the claim that the bulk electronic structures can be preserved even after the freestanding treatment process. The 3sPFY spectrum obtained from analyzing the RIXS maps offers a powerful way to probe the bulk electronic structures in thin films and heterostructures when recording the XAS spectra in the transmission mode is not available.

Large-scale fabrication of a flexible, highly conductive composite paper based on molybdenum disulfide-Pt nanoparticle-single-walled carbon nanotubes for efficient hydrogen production.

Creating efficient hydrogen production properties from the macroscopic assembly of two-dimensional materials is still an unaccomplished goal. Here we report a facile route to fabricate a flexible MoS2/PtNPs/SWCNT paper with an ultralow onset potential of -35 mV, a Tafel slope of 39.6 mV per decade and over 60 h of electrochemical durability.

The pulse spectrum analysis at three stages of pregnancy.

OBJECTIVES: This study is the first to detect the radial pulses of the three diagnosis positions (inch, bar, and cubit) in both wrists (six positions) by pulse spectrum analysis. The purpose of this study was to identify the difference among pulses of the six positions at three stages of pregnancy and to examine whether the results of this study agree with the theory of Traditional Chinese Medicine (TCM), which states that the cubit pulse shows unique changes for an expectant woman and that the pulse changes coincide with the progression of gestation. SUBJECTS AND METHODS: One hundred and fifty (150) healthy pregnant women were divided into three groups according to gestational age (9-14 weeks, 20-28 weeks, and 32-37 weeks of gestation) and 50 healthy nonpregnant women were used as controls. A pulse analyzer was used to detect the six positions of the radial pulses and to calculate the 10 relative energy values of the spectrum's harmonics of the six positions. RESULTS: Results show that most of the 10 relative spectral energy values of the right and left cubits are statistically (p<0.01) higher than those of the inch for the pregnant women as compared with the nonpregnant women. In addition, the 10 relative spectral energy values of the six positions are not identical at the three stages of pregnancy. CONCLUSIONS: The cubit pulse is unique for pregnant women, which is consistent with the theory of TCM. In addition, the pulse conditions at the three stages of pregnancy are dissimilar.

Pediatric ovarian torsion in a medical center in Taiwan: case analysis.

BACKGROUND: Abdominal pain is one of the most common complaints made by patients visiting emergency departments; however, ovarian torsion is an uncommon cause of abdominal pain, especially in young children. Early diagnosis is essential in order to salvage the ovaries. We performed a retrospective analysis of patients under 18 years of age who visited Changhua Christian Hospital with adnexal torsion between June 2003 and June 2010. METHODS: Medical records were reviewed for age, associated symptoms, past and present medical histories, physical findings, diagnostic tests performed, clinical course, pathological findings, and diagnoses. RESULTS: A total of 21 patients were identified and included in the analysis; their mean (SD) age was 13.62 (3.75) years. Abdominal pain was the universal symptom. Vomiting or nausea was the second most common symptom (33.3%). The average period between symptom onset and diagnosis was 3.29 (6.39) days. Right-side adnexal torsion occurred in 14 patients, and left-side torsion in seven patients. Ovarian cysts, most often dermoid cysts (e.g., teratomas), were found in 16 patients (76%). Except for one conservatively treated case and one malignant case (adult granulose cell tumor), the other results of the pathological examination were as follows: eight dermoid cysts, two cystadenomas, one follicular cyst, and eight simple cysts. CONCLUSION: Although it is uncommon, adnexal torsion should be included in the differential diagnosis of lower abdominal pain in all girls, regardless of age. Sonography is helpful for making such a diagnosis. Time is a critical factor, and early laparoscopy or laparotomy may save a viable ovary.

Differences in pulse spectrum analysis between atopic dermatitis and nonatopic healthy children.

OBJECTIVES: Atopic dermatitis (AD) is a common allergy that causes the skin to be dry and itchy. It appears at an early age, and is closely associated with asthma and allergic rhinitis. Thus, AD is an indicator that other allergies may occur later. Literatures indicate that the molecular basis of patients with AD is different from that of healthy individuals. According to the classics of Traditional Chinese Medicine, the body constitution of patients with AD is also different. The purpose of this study is to determine the differences in pulse spectrum analysis between patients with AD and nonatopic healthy individuals. METHODS: A total of 60 children (30 AD and 30 non-AD) were recruited for this study. A pulse spectrum analyzer (SKYLARK PDS-2000 Pulse Analysis System) was used to measure radial arterial pulse waves of subjects. Original data were then transformed to frequency spectrum by Fourier transformation. The relative strength of each harmonic wave was calculated. Moreover, the differences of harmonic values between patients with AD and non-atopic healthy individuals were compared and contrasted. RESULTS: This study showed that harmonic values and harmonic percentage of C3 (Spleen Meridian, according to Wang's hypothesis) were significantly different. CONCLUSIONS: These results demonstrate that C3 (Spleen Meridian) is a good index for the determination of atopic dermatitis. Furthermore, this study demonstrates that the pulse spectrum analyzer is a valuable auxiliary tool to distinguish a patient who has probable tendency to have AD and/or other allergic diseases.

Intraocular pressure-lowering effect of auricular acupressure in patients with glaucoma: a prospective, single-blinded, randomized controlled trial.

OBJECTIVE: The objective of the study was to evaluate the effect of auricular acupressure in controlling intraocular pressure (IOP) in patients with glaucoma. DESIGN: Thirty-three (33) patients were recruited through advertisement at the clinic for glaucoma. These patients were divided into the auricular acupressure group (16 patients, 28 glaucoma eyes) and the sham group (17 patients, 32 glaucoma eyes). Patients in the acupressure group received auricular acupoint (kidney, liver, and eye) stimulator tapping and regular massage twice a day for 4 weeks. Patients in the sham group received tapping at sham auricular acupoints (wrist, shoulder, and jaw) without massage stimulation. The IOP and visual acuity (VA) were assessed before and after the treatment in the first 4 weeks and followed up, up to 8 weeks. RESULTS: After the treatment and at the 8-week follow-up, IOP and VA improved significantly in the acupressure group when compared with pretreatment (p < 0.05). The most significant IOP-lowering effect was seen at about 3-4 weeks after auricular acupressure. IOP returned to the initial level after acupressure had been discontinued for 4 weeks. Significant improvement of the uncorrected VA (UCVA) was noted at about 2-4 weeks in the acupressure group. UCVA improvement was also noted in the sham group. The difference was only significant in week 3. Improvement of the best-corrected VA was noted in both groups, but was only significant in week 2. CONCLUSIONS: Our data suggest that auricular acupressure can be used as a complementary treatment to ameliorate IOP and VA for patients with glaucoma.