Beamline simulations using monochromators with high d-spacing crystals.

Monochromators for synchrotron radiation beamlines typically use perfect crystals for the hard X-ray regime and gratings for soft X-rays. There is an intermediate range, typically 1-3 keV (tender X-rays), which common perfect crystals have difficulties covering and gratings have low efficiency, although some less common crystals with high d-spacing could be suitable. To evaluate the suitability of these crystals for a particular beamline, it is useful to evaluate the crystals' performance using tools such as ray-tracing. However, simulations for double-crystal monochromators are only available for the most used crystals such as Si, Ge or diamond. Here, an upgrade of the SHADOW ray-tracing code and complementary tools in the OASYS suite are presented to simulate high d-spacing crystals with arbitrary, and sometimes complex, structures such as beryl, YB66, muscovite, etc. Isotropic and anisotropic temperature factors are also considered. The YB66 crystal with 1936 atomic sites in the unit cell is simulated, and its applicability for tender X-ray monochromators is discussed in the context of new low-emittance storage rings.

Correlations between photosynthetic heat tolerance and leaf anatomy and climatic niche in Asian mangrove trees.

Photosynthetic heat tolerance (PHT ) is a key predictor of plant response to climate change. Mangroves are an ecologically and economically important coastal plant community comprised of trees growing at their physiological limits. Mangroves are currently impacted by global warming, yet the PHT of mangrove trees is poorly understood. In this study, we provide the first assessment of PHT in 13 Asian mangrove species, based on the critical temperature that causes the initial damage (TCrit ) and the temperature that causes 50% damage (T50 ) to photosystem II. We tested the hypotheses that the PHT in mangroves is: (i) correlated with climatic niche and leaf traits, and (ii) higher than in plants from other tropical ecosystems. Our results demonstrated correlations between PHT and multiple key climate variables, the palisade to spongy mesophyll ratio and the leaf area. The two most heat-sensitive species were Kandelia obovata and Avicennia marina. Our study also revealed that mangrove trees show high heat tolerance compared to plants from other tropical ecosystems. The high PHT of mangroves thus demonstrated a conservative evolutionary strategy in heat tolerance, and highlights the need for integrative and comparative studies on thermoregulatory traits and climatic niche in order to understand the physiological response of mangrove trees to climate change-driven heatwaves and rising global temperatures.

Observation of perfect diamagnetism and interfacial effect on the electronic structures in infinite layer Nd0.8Sr0.2NiO2 superconductors.

Nickel-based complex oxides have served as a playground for decades in the quest for a copper-oxide analog of the high-temperature superconductivity. They may provide clues towards understanding the mechanism and an alternative route for high-temperature superconductors. The recent discovery of superconductivity in the infinite-layer nickelate thin films has fulfilled this pursuit. However, material synthesis remains challenging, direct demonstration of perfect diamagnetism is still missing, and understanding of the role of the interface and bulk to the superconducting properties is still lacking. Here, we show high-quality Nd0.8Sr0.2NiO2 thin films with different thicknesses and demonstrate the interface and strain effects on the electrical, magnetic and optical properties. Perfect diamagnetism is achieved, confirming the occurrence of superconductivity in the films. Unlike the thick films in which the normal-state Hall-coefficient changes signs as the temperature decreases, the Hall-coefficient of films thinner than 5.5 nm remains negative, suggesting a thickness-driven band structure modification. Moreover, X-ray absorption spectroscopy reveals the Ni-O hybridization nature in doped infinite-layer nickelates, and the hybridization is enhanced as the thickness decreases. Consistent with band structure calculations on the nickelate/SrTiO3 heterostructure, the interface and strain effect induce a dominating electron-like band in the ultrathin film, thus causing the sign-change of the Hall-coefficient.

Unravelling strong electronic interlayer and intralayer correlations in a transition metal dichalcogenide.

Electronic correlations play important roles in driving exotic phenomena in condensed matter physics. They determine low-energy properties through high-energy bands well-beyond optics. Great effort has been made to understand low-energy excitations such as low-energy excitons in transition metal dichalcogenides (TMDCs), however their high-energy bands and interlayer correlation remain mysteries. Herewith, by measuring temperature- and polarization-dependent complex dielectric and loss functions of bulk molybdenum disulphide from near-infrared to soft X-ray, supported with theoretical calculations, we discover unconventional soft X-ray correlated-plasmons with low-loss, and electronic transitions that reduce dimensionality and increase correlations, accompanied with significantly modified low-energy excitons. At room temperature, interlayer electronic correlations, together with the intralayer correlations in the c-axis, are surprisingly strong, yielding a three-dimensional-like system. Upon cooling, wide-range spectral-weight transfer occurs across a few tens of eV and in-plane p-d hybridizations become enhanced, revealing strong Coulomb correlations and electronic anisotropy, yielding a two-dimensional-like system. Our result shows the importance of strong electronic, interlayer and intralayer correlations in determining electronic structure and opens up applications of utilizing TMDCs on plasmonic nanolithrography.

Oxygen Electromigration and Energy Band Reconstruction Induced by Electrolyte Field Effect at Oxide Interfaces.

Electrolyte gating is a powerful means for tuning the carrier density and exploring the resultant modulation of novel properties on solid surfaces. However, the mechanism, especially its effect on the oxygen migration and electrostatic charging at the oxide heterostructures, is still unclear. Here we explore the electrolyte gating on oxygen-deficient interfaces between SrTiO_{3} (STO) crystals and LaAlO_{3} (LAO) overlayer through the measurements of electrical transport, x-ray absorption spectroscopy, and photoluminescence spectra. We found that oxygen vacancies (O_{vac}) were filled selectively and irreversibly after gating due to oxygen electromigration at the amorphous LAO/STO interface, resulting in a reconstruction of its interfacial band structure. Because of the filling of O_{vac}, the amorphous interface also showed an enhanced electron mobility and quantum oscillation of the conductance. Further, the filling effect could be controlled by the degree of the crystallinity of the LAO overlayer by varying the growth temperatures. Our results reveal the different effects induced by electrolyte gating, providing further clues to understand the mechanism of electrolyte gating on buried interfaces and also opening a new avenue for constructing high-mobility oxide interfaces.

Unusual case of lipoma arborescens in the subacromial-subdeltoid bursa.

A 38-year-old female presented with a 10-month history of right shoulder pain with impingement symptoms. She was diagnosed on magnetic resonance (MR) imaging to have supraspinatus tendon tear and degenerative changes contributing to subacromial impingement. She also had lipoma arborescens of the subacromial-subdeltoid bursa, an uncommon condition in a particularly rare location. Lipoma arborescens is a benign intra-articular condition characterized by lipomatous proliferation of synovium with replacement of subsynovial tissue by mature adipocytes. It is typically a monoarticular process affecting the knee. Due to the presence of pathognomonic fat, diagnosis is usually straightforward with MR as the preferred imaging modality.

A novel, somatic, transforming mutation in the extracellular domain of Epidermal Growth Factor Receptor identified in myeloproliferative neoplasm.

We describe a novel ERBB1/EGFR somatic mutation (p. C329R; c.985 T > C) identified in a patient with JAK2V617F Polycythaemia Vera (PV). This substitution affects a conserved cysteine residue in EGFR domain 2 and leads to the formation of a ligand-independent covalent receptor dimer, associated with increased transforming potential. Aberrant signalling from the EGFRC329R receptor is cell type-dependent and in the TF1.8 erythroid cell line expression of this mutant suppresses EPO-induced differentiation. Clonal analysis shows that the dominant JAK2V617F-positive clone in this PV patient harbors EGFRC329R, thus this mutation may contribute to clonal expansion. Somatic mutations affecting other ERBB and related receptor tyrosine kinases are observed in myeloproliferative neoplasms (MPN), and we show elevated EGFR levels in MPN samples, consistent with previous reports. Thus activation of this group of receptors, via multiple mechanisms, may contribute to clonal growth and survival of the JAK2V617F disease clone in MPN.

The surface electronic structure of silicon terminated (100) diamond.

A combination of synchrotron-based x-ray spectroscopy and contact potential difference measurements have been used to examine the electronic structure of the (3 × 1) silicon terminated (100) diamond surface under ultra high vacuum conditions. An occupied surface state which sits 1.75 eV below the valence band maximum has been identified, and indications of mid-gap unoccupied surface states have been found. Additionally, the pristine silicon terminated surface is shown to possess a negative electron affinity of -0.86 ± 0.1 eV.

Anomalous spectral features of a neutral bilayer graphene.

Graphene and its bilayer are two-dimensional systems predicted to show exciting many-body effects near the neutrality point. The ideal tool to investigate spectrum reconstruction effects is angle-resolved photoemission spectroscopy (ARPES) as it probes directly the band structure with information about both energy and momentum. Here we reveal, by studying undoped exfoliated bilayer graphene with ARPES, two essential aspects of its many-body physics: the electron-phonon scattering rate has an anisotropic k-dependence and the type of electronic liquid is non-Fermi liquid. The latter behavior is evident from an observed electron-electron scattering rate that scales linearly with energy from 100 meV to 600 meV and that is associated with the proximity of bilayer graphene to a two-dimensional quantum critical point of competing orders.

Optimized growth of graphene on SiC: from the dynamic flip mechanism.

Thermal decomposition of single-crystal SiC is one of the popular methods for growing graphene. However, the mechanism of graphene formation on the SiC surface is poorly understood, and the application of this method is also hampered by its high growth temperature. In this study, based on the ab initio calculations, we propose a vacancy assisted Si-C bond flipping model for the dynamic process of graphene growth on SiC. The fact that the critical stages during growth take place at different energy costs allows us to propose an energetic-beam controlled growth method that not only significantly lowers the growth temperature but also makes it possible to grow high-quality graphene with the desired size and patterns directly on the SiC substrate.

Oral cancer screening and dental care use among women from Ohio Appalachia.

INTRODUCTION: Residents of Appalachia may benefit from oral cancer screening given the region's higher oral and pharyngeal cancer mortality rates. The current study examined the oral cancer screening behaviors and recent dental care (since dentists perform most screening examinations) of women from Ohio Appalachia. METHODS: Women from Ohio Appalachia were surveyed for the Community Awareness Resources Education (CARE) study, which was completed in 2006. A secondary aim of the CARE baseline survey was to examine oral cancer screening and dental care use among women from this region. Outcomes included whether women (n=477; cooperation rate = 71%) had ever had an oral cancer screening examination and when their most recent dental visit had occurred. Various demographic characteristics, health behaviors and psychosocial factors were examined as potential correlates. Analyses used multivariate logistic regression. RESULTS: Most women identified tobacco-related products as risk factors for oral cancer, but 43% of women did not know an early sign of oral cancer. Only 15% of women reported ever having had an oral cancer screening examination, with approximately 80% of these women indicating that a dentist had performed their most recent examination. Women were less likely to have reported a previous examination if they were from urban areas (OR=0.33, 95% CI: 0.13-0.85) or perceived a lower locus of health control (OR=0.94, 95% CI: 0.89-0.98). Women were more likely to have reported a previous examination if they had had a dental visit within the last year (OR=2.24, 95% CI: 1.03-4.88). Only 65% of women, however, indicated a dental visit within the last year. Women were more likely to have reported a recent dental visit if they were of a high socioeconomic status (OR=2.83, 95% CI: 1.58-5.06), had private health insurance (OR=2.20, 95% CI: 1.21-3.97) or had consumed alcohol in the last month (OR=2.03, 95% CI: 1.20-3.42). CONCLUSION: Oral cancer screening was not common among women from Ohio Appalachia, with many missed opportunities having occurred at dental visits. Education programs targeting dentists and other healthcare providers (given dental providers are lacking in some areas of Ohio Appalachia) about opportunistic oral cancer screening may help to improve screening in Appalachia. These programs should include information about populations at high risk for oral cancer (eg smokers) and how screening may be especially beneficial for them. Future research is needed to examine the acceptability of such education programs to healthcare providers in the Appalachian region and to explore why screening was less common among women living in urban areas of Ohio Appalachia.

Cationic-vacancy-induced room-temperature ferromagnetism in transparent, conducting anatase Ti1-xTaxO2 (x~0.05) thin films.

We report room-temperature ferromagnetism (FM) in highly conducting, transparent anatase Ti(1-x)Ta(x)O(2) (x∼0.05) thin films grown by pulsed laser deposition on LaAlO(3) substrates. Rutherford backscattering spectrometry (RBS), X-ray diffraction, proton-induced X-ray emission, X-ray absorption spectroscopy (XAS) and time-of-flight secondary-ion mass spectrometry indicated negligible magnetic contaminants in the films. The presence of FM with concomitant large carrier densities was determined by a combination of superconducting quantum interference device magnetometry, electrical transport measurements, soft X-ray magnetic circular dichroism (SXMCD), XAS and optical magnetic circular dichroism, and was supported by first-principles calculations. SXMCD and XAS measurements revealed a 90 per cent contribution to FM from the Ti ions, and a 10 per cent contribution from the O ions. RBS/channelling measurements show complete Ta substitution in the Ti sites, though carrier activation was only 50 per cent at 5 per cent Ta concentration, implying compensation by cationic defects. The role of the Ti vacancy (V(Ti)) and Ti(3+) was studied via XAS and X-ray photoemission spectroscopy, respectively. It was found that, in films with strong FM, the V(Ti) signal was strong while the Ti(3+) signal was absent. We propose (in the absence of any obvious exchange mechanisms) that the localized magnetic moments, V(Ti) sites, are ferromagnetically ordered by itinerant carriers. Cationic-defect-induced magnetism is an alternative route to FM in wide-band-gap semiconducting oxides without any magnetic elements.

Fine needle aspiration biopsy of hepatocellular carcinoma and hepatocellular nodular lesions: role, controversies and approach to diagnosis.

The role of fine needle aspiration (FNA) biopsy of the liver has evolved. Advances in imaging modalities have obviated the need for tissue confirmation in clinically classic hepatocellular carcinoma (HCC). The risks of needle tract seeding and haematogenous dissemination have been actively debated. Nowadays, cytopathologists are confronted by smaller and smaller nodules, detected due to increased surveillance of high-risk cirrhotic patients. Tissue characterization of small well-differentiated hepatocellular nodular lesions (size less than and equal to 2 cm) is extremely challenging and has therapeutic implications. Major issues in the cytodiagnosis of HCC include: (i) distinguishing benign hepatocellular nodular lesions, namely, large regenerative nodules, dysplastic nodules, focal nodular hyperplasia and hepatocellular adenoma from reactive hepatocytes; (ii) distinguishing well-differentiated HCC from benign hepatocellular nodular lesions; (iii) distinguishing poorly differentiated HCC from intrahepatic cholangiocarcinoma and metastatic carcinomas; (iv) determining the histogenesis of a malignant tumour; and (v) determining the site of origin of a malignant tumour. An overview of the biological evolution and histopathological aspects of dysplastic nodules, small HCCs and 'nodule-in-nodule' lesions is presented in tandem with clinically relevant nomenclature. An algorithmic approach to FNA diagnosis of HCC and hepatocellular nodular lesions is outlined. Optimal results depend on (i) a dedicated radiologist-cytopathologist team; (ii) an on-site cytology service, (iii) a combined cytohistological approach, (iv) immunohistochemistry, and (v) clinicopathological correlation. As we move towards personalized medicine, it is envisaged that hepatic FNA is likely to become a point of care in the management protocol as it takes on the additional role of procurement of tumour and peritumoural tissues for genomic and proteomic profiling to enable targeted molecular therapy.

High-dose intravenous rituximab for multifocal, monomorphic primary central nervous system posttransplant lymphoproliferative disorder.

Primary central nervous system (CNS) posttransplant lymphoproliferative disorder (PTLD) is a well-recognized but rare complication of solid organ transplantation. Most of these disorders are B-cell in origin and generally carry poor prognosis. Rituximab, an anti-CD20 monoclonal antibody, has been used effectively in patients with systemic PTLD. However, its role in primary CNS PTLD is doubtful because it does not cross blood-brain barrier efficiently (<5%). Also, mechanisms, by which rituximab operates are not optimally effective in CNS. Here, we describe a renal transplant patient with monomorphic, multifocal, CD20-positive, primary B-cell CNS PTLD, who was treated with high-dose intravenous rituximab given in dose-escalation protocol, which has been used effectively for the patients with chronic lymphocytic leukemia. At 1-year follow-up, magnetic resonance imaging (MRI) showed complete resolution. High-dose rituximab may have a role in highly selected patients with primary CNS PTLD.

Experimental observation of the crystallization of a paired holon state.

An excitation at 201 meV is observed in the doped-hole ladder cuprate Sr14Cu24O41, using ultraviolet resonance Raman scattering with incident light at 3.7 eV polarized along the rungs. The excitation is of charge nature, with a temperature independent excitation energy, and can be understood via an intraladder pair-breaking process. The intensity tracks closely the order parameter of the charge density wave in the ladder CDW(L), but persists above its transition temperature T(CDW(L)), indicating a strong local pairing above the T(CDW(L)). The 201 meV excitation vanishes in La6Ca8Cu24O(41+δ), and La5Ca9Cu24O41 which are samples with no holes in the ladders. Our results suggest that the doped holes in the ladder are composite bosons consisting of paired holons that order below T(CDW).

Assessing tooth color differences in digital facial portraits.

Although a large body of scientific literature shows that background color and luminance affect color perception, previous measurements of tooth color difference thresholds have not taken the effects of viewing context into account. The present study tested the hypothesis that differences in skin/gingival color influence individuals' judgments of tooth color differences. Perceptibility and acceptability thresholds were determined in 10 individuals using a signal detection paradigm. They evaluated 500 pseudo-random presentations of two facial portraits: an African-American and a Caucasian. These portraits varied trial-to-trial only in the direction (CIELAB +L*, +a*, or +b*) or magnitude of the color difference between a portrait's two central incisors. The individuals were significantly less sensitive to tooth color differences in the +L* direction in the Caucasian portrait than for any other combination of color direction or portrait type. Furthermore, comparable perceptibility and acceptability thresholds were generally not statistically significant from each other.

Ferromagnetism in dilute magnetic semiconductors through defect engineering: Li-doped ZnO.

We demonstrate, both theoretically and experimentally, that cation vacancy can be the origin of ferromagnetism in intrinsic dilute magnetic semiconductors. The vacancies can be controlled to tune the ferromagnetism. Using Li-doped ZnO as an example, we found that while Li itself is nonmagnetic, it generates holes in ZnO, and its presence reduces the formation energy of Zn vacancy, and thereby stabilizes the zinc vacancy. Room temperature ferromagnetism with p type conduction was observed in pulsed laser deposited ZnO:Li films with certain doping concentration and oxygen partial pressure.