Tunneling Plasmonics in Bilayer Graphene

We report experimental signatures of plasmonic effects due to electron tunneling between adjacent graphene layers. At subnanometer separation, such layers can form either a strongly coupled bilayer graphene with a Bernal stacking or a weakly coupled double-layer graphene with a random stacking order. Effects due to interlayer tunneling dominate in the former case but are negligible in the latter. We found through infrared nanoimaging that bilayer graphene supports plasmons with a higher degree of confinement compared to single- and double-layer graphene, a direct consequence of interlayer tunneling. Moreover, we were able to shut off plasmons in bilayer graphene through gating within a wide voltage range. Theoretical modeling indicates that such a plasmon-off region is directly linked to a gapped insulating state of bilayer graphene, yet another implication of interlayer tunneling. Our work uncovers essential plasmonic properties in bilayer graphene and suggests a possibility to achieve novel plasmonic functionalities in graphene few-layers.

Clinicopathological and phenotypic features of chronic NK cell lymphocytosis identified among patients with asymptomatic lymphocytosis

INTRODUCTION

Chronic natural killer (NK) cell lymphocytosis is currently a provisional entity. This study demonstrated NK cell lymphocytosis in patients with asymptomatic lymphocytosis and presented the hematological and phenotypic findings.

METHODS

Flow cytometry analysis was performed for investigation of unexplained peripheral lymphocytosis. NK cells were determined by the phenotype of CD3-/CD16+/CD56+. Chronic NK cell lymphocytosis was defined by a NK cell count of ≥ 2 × 10(9)/L, persistent for over 6 months, no evidence of B- or T-cell clonality and no hematologic disorders.

RESULTS

Among 190 patients with peripheral lymphocytosis, 15(7.9%) patients, age 42-72 years, were identified to have NK cell lymphocytosis, with a median NK cell count of 3.1 × 10(9)/L (range 2.1-7.3 × 10(9)/L). Persistent NK cell lymphocytosis was confirmed with a median follow-up of 18 months. CD56(bright) NK cell populations were seen in eight patients and CD56(dim) NK cells in seven patients. CD57 co-expression was seen in both CD56(dim) and CD56(bright) cells. CD7, CD2, or CD8 expression was seen in some of the NK populations. The NK cell lymphocytosis appeared stable and no progression to NK cell leukemia during the follow-up period.

CONCLUSION

This study demonstrated that chronic NK cell lymphocytosis, similar to monoclonal B lymphocytosis or T-cell clones, may account for asymptomatic lymphocytosis. There were no identifiable causes of the NK cell expansion. The variable phenotype may represent the heterogeneity and pathological features of NK lymphocytosis.

Graphene on hexagonal boron nitride as a tunable hyperbolic metamaterial

Hexagonal boron nitride (h-BN) is a natural hyperbolic material, in which the dielectric constants are the same in the basal plane (ε(t) ≡ ε(x) = ε(y)) but have opposite signs (ε(t)ε(z) < 0) in the normal plane (ε(z)). Owing to this property, finite-thickness slabs of h-BN act as multimode waveguides for the propagation of hyperbolic phonon polaritons--collective modes that originate from the coupling between photons and electric dipoles in phonons. However, control of these hyperbolic phonon polaritons modes has remained challenging, mostly because their electrodynamic properties are dictated by the crystal lattice of h-BN. Here we show, by direct nano-infrared imaging, that these hyperbolic polaritons can be effectively modulated in a van der Waals heterostructure composed of monolayer graphene on h-BN. Tunability originates from the hybridization of surface plasmon polaritons in graphene with hyperbolic phonon polaritons in h-BN, so that the eigenmodes of the graphene/h-BN heterostructure are hyperbolic plasmon-phonon polaritons. The hyperbolic plasmon-phonon polaritons in graphene/h-BN suffer little from ohmic losses, making their propagation length 1.5-2.0 times greater than that of hyperbolic phonon polaritons in h-BN. The hyperbolic plasmon-phonon polaritons possess the combined virtues of surface plasmon polaritons in graphene and hyperbolic phonon polaritons in h-BN. Therefore, graphene/h-BN can be classified as an electromagnetic metamaterial as the resulting properties of these devices are not present in its constituent elements alone.

Subdiffractional focusing and guiding of polaritonic rays in a natural hyperbolic material

Uniaxial materials whose axial and tangential permittivities have opposite signs are referred to as indefinite or hyperbolic media. In such materials, light propagation is unusual leading to novel and often non-intuitive optical phenomena. Here we report infrared nano-imaging experiments demonstrating that crystals of hexagonal boron nitride, a natural mid-infrared hyperbolic material, can act as a ‘hyper-focusing lens' and as a multi-mode waveguide. The lensing is manifested by subdiffractional focusing of phonon–polaritons launched by metallic disks underneath the hexagonal boron nitride crystal. The waveguiding is revealed through the modal analysis of the periodic patterns observed around such launchers and near the sample edges. Our work opens new opportunities for anisotropic layered insulators in infrared nanophotonics complementing and potentially surpassing concurrent artificial hyperbolic materials with lower losses and higher optical localization.

Hexagonal boron nitride has many interesting properties, including a natural hyperbolic dispersion, making it attractive for nanophotonic applications. Here, Dai et al. show that metallic disks under the material launch phonon–polaritons, turning it into a hyper-focusing lens.

Evaluation of clinical measurements and development of new diagnostic criteria for Takayasu arteritis in a Chinese population

OBJECTIVES

Takayasu arteritis (TA) is a chronic granulomatous large-vessel vasculitis. When diagnosing TA, the criteria designed by the American College of Rheumatology (ACR) are used commonly but they were just classification criteria. There is an urgent need for a new set of diagnostic criteria.

METHODS

One hundred and thirty-one TA patients and 132 control patients with other types of vascular disease were enrolled and both groups were distributed into a "training set" and a "validation set". All general information as well as clinical, laboratory and imaging data were collected. After comparing all the medical records of two groups in the training set, logistic regression and clinical judgment were used to form the new criteria for TA. The new criteria were tested by the validation set.

RESULTS

New TA diagnostic criteria within total score 26 include age (<40 years), female, chest pain/chest distress, amaurosis, vascular bruits, a decreased/absent pulse, involvement of the aortic arch or its major branches, and involvement of the abdominal aorta or its branches. Patients with a score ≥ 8 were diagnosed as TA. The sensitivity and specificity of our new criteria were 91.92% and 93.94%, respectively, higher than those of the ACR criteria (75.76%, 85.86%) and the Ishikawa criteria (56.57%, 94.95%). The areas under the ROC curves of the new criteria and ACR criteria were 0.981 and 0.868, respectively (p<0.001). Sensitivity and specificity tested in the validation set were 90.63% and 96.97%, respectively.

CONCLUSIONS

The new diagnostic criteria exhibited high sensitivity and specificity and have demonstrated to be feasible in the diagnosis of TA.

Transport of ions in mesoporous carbon electrodes during capacitive deionization of high-salinity solutions

Desalination of high-salinity solutions has been studied using a novel experimental technique and a theoretical model. Neutron imaging has been employed to visualize lithium ions in mesoporous carbon materials, which are used as electrodes in capacitive deionization (CDI) for water desalination. Experiments were conducted with a flow-through CDI cell designed for neutron imaging and with lithium-6 chloride ((6)LiCl) as the electrolyte. Sequences of neutron images have been obtained at a relatively high concentration of (6)LiCl solution to provide information on the transport of ions within the electrodes. A new model that computes the individual ionic concentration profiles inside mesoporous carbon electrodes has been used to simulate the CDI process. Modifications have also been introduced into the simulation model to calculate results at high electrolyte concentrations. Experimental data and simulation results provide insight into why CDI is not effective for desalination of high ionic-strength solutions. The combination of experimental information, obtained through neutron imaging, with the theoretical model will help in the design of CDI devices, which can improve the process for high ionic-strength solutions.

Involvement of NLRP3 inflammasome in rituximab-induced interstitial lung disease: a case report

WHAT IS KNOWN AND OBJECTIVE

Rituximab is a chimeric anti-CD20 IgG1 monoclonal antibody for the treatment of various forms of lymphoma and haematological autoimmune diseases. Interstitial lung disease is a rare but lethal pulmonary toxicity of rituximab. Nod-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome is a molecular platform activated upon signs of cellular 'danger' to trigger the maturation of pro-inflammatory cytokines. We report the first case of rituximab-induced interstitial lung disease (R-ILD) with NLRP3 inflammasome activation in the lung.

CASE SUMMARY

A 30-year-old male patient diagnosed with idiopathic thrombocytopenic purpura (ITP) was treated with four cycles of rituximab in one month. Three weeks after last rituximab administration, he developed progressive dyspnoea associated with respiratory failure, which was diagnosed as R-ILD. The patient showed a good response to steroid treatment, and lung biopsy was performed 5 days after the treatment. Immunohistopathological studies of lung specimens showed high expressions of inflammasome components NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) and caspase-1 in lung interstitium with a heavy infiltration of CD19-positive cells. The levels of inflammasome-related cytokines IL-1β and IL-18 in the serum were declined during the therapy.

WHAT IS NEW AND CONCLUSIONS

This is the first report confirmed the role of NLRP3 inflammasome in pulmonary toxicity of rituximab. Inhibited activation of NLRP3 inflammasome in lung by steroid treatment could reverse R-ILD and block subsequent lung fibrosis. This result could open a new sight into the pathogenesis and provide a new target for the treatment of R-ILD.

Postsynaptic scaffold protein Homer 1a protects against traumatic brain injury via regulating group I metabotropic glutamate receptors

Traumatic brain injury (TBI) produces excessive glutamate, leading to excitotoxicity via the activation of glutamate receptors. Postsynaptic density scaffold proteins have crucial roles in mediating signal transduction from glutamate receptors to their downstream mediators. Therefore, studies on the mechanisms underlying regulation of excitotoxicity by scaffold proteins can uncover new treatments for TBI. Here, we demonstrated that the postsynaptic scaffold protein Homer 1a was neuroprotective against TBI in vitro and in vivo, and this neuroprotection was associated with its effects on group I metabotropic glutamate receptors (mGluRs). Upon further study, we found that Homer 1a mainly affected neuronal injury induced by mGluR1 activation after TBI and also influenced mGluR5 function when its activity was restored. The ability of Homer 1a to disrupt mGluR-ERK signaling contributed to its ability to regulate the functions of mGluR1 and mGluR5 after traumatic injury. Intracellular Ca(2+) and PKC were two important factors involved in the mediation of mGluR-ERK signaling by Homer 1a. These results define Homer 1a as a novel endogenous neuroprotective agent against TBI.

Tunable phonon polaritons in atomically thin van der Waals crystals of boron nitride

van der Waals heterostructures assembled from atomically thin crystalline layers of diverse two-dimensional solids are emerging as a new paradigm in the physics of materials. We used infrared nanoimaging to study the properties of surface phonon polaritons in a representative van der Waals crystal, hexagonal boron nitride. We launched, detected, and imaged the polaritonic waves in real space and altered their wavelength by varying the number of crystal layers in our specimens. The measured dispersion of polaritonic waves was shown to be governed by the crystal thickness according to a scaling law that persists down to a few atomic layers. Our results are likely to hold true in other polar van der Waals crystals and may lead to new functionalities.

Metabolic syndrome and chronic disease

INTRODUCTION

Metabolic syndrome (MetS) is a combination of risk markers that appear to promote the development of chronic disease. We examined the burden of MetS in Canada through its current and projected association with chronic disease.

METHODS

We used measures from the Canadian Health Measures Survey 2007-2009 to identify the prevalence of MetS in Canadian adults and examine associations between sociodemographic factors and major chronic diseases. We estimated the projected cumulative incidence of diabetes and percent risk of a fatal cardiovascular event using the Diabetes Population Risk Tool (DPoRT) and Framingham algorithms.

RESULTS

After adjusting for age, we found that 14.9% of Canadian adults had MetS. Rates were similar in both sexes, but higher in those who are non-Caucasian or overweight or obese (p < .001 for all three). The importance of MetS for public health was demonstrated by its significant association with chronic disease relative to the general population, particularly for diagnosed (11.2% vs. 3.4%) and undiagnosed (6.0% vs. 1.1%) type 2 diabetes. The ten-year incidence estimate for diabetes and mean percent risk of a fatal cardiovascular disease (CVD) event were higher in those with MetS compared to those without (18.0% vs. 7.1% for diabetes, and 4.1% vs. 0.8% for CVD).

CONCLUSION

MetS is prevalent in Canadian adults and a high proportion of individuals with MetS have diagnosed or undiagnosed chronic conditions. Projection estimates for the incidence of chronic disease associated with MetS demonstrate higher rates in individuals with this condition. Thus, MetS may be a relevant risk factor in the development of chronic disease.

Metabolic syndrome and chronic disease

Introduction

Metabolic syndrome (MetS) is a combination of risk markers that appear to promote the development of chronic disease. We examined the burden of MetS in Canada through its current and projected association with chronic disease.

Methods

We used measures from the Canadian Health Measures Survey 2007–2009 to identify the prevalence of MetS in Canadian adults and examine associations between sociodemographic factors and major chronic diseases. We estimated the projected cumulative incidence of diabetes and percent risk of a fatal cardiovascular event using the Diabetes Population Risk Tool (DPoRT) and Framingham algorithms.

Results

After adjusting for age, we found that 14.9% of Canadian adults had MetS. Rates were similar in both sexes, but higher in those who are non-Caucasian or overweight or obese (p $lt; .001 for all three). The importance of MetS for public health was demonstrated by its significant association with chronic disease relative to the general population, particularly for diagnosed (11.2% vs. 3.4%) and undiagnosed (6.0% vs. 1.1%) type 2 diabetes. The ten-year incidence estimate for diabetes and mean percent risk of a fatal cardiovascular disease (CVD) event were higher in those with MetS compared to those without (18.0% vs. 7.1% for diabetes, and 4.1% vs. 0.8% for CVD).

Conclusion

MetS is prevalent in Canadian adults and a high proportion of individuals with MetS have diagnosed or undiagnosed chronic conditions. Projection estimates for the incidence of chronic disease associated with MetS demonstrate higher rates in individuals with this condition. Thus, MetS may be a relevant risk factor in the development of chronic disease.

Electronic and plasmonic phenomena at graphene grain boundaries

Graphene, a two-dimensional honeycomb lattice of carbon atoms of great interest in (opto)electronics and plasmonics, can be obtained by means of diverse fabrication techniques, among which chemical vapour deposition (CVD) is one of the most promising for technological applications. The electronic and mechanical properties of CVD-grown graphene depend in large part on the characteristics of the grain boundaries. However, the physical properties of these grain boundaries remain challenging to characterize directly and conveniently. Here we show that it is possible to visualize and investigate the grain boundaries in CVD-grown graphene using an infrared nano-imaging technique. We harness surface plasmons that are reflected and scattered by the graphene grain boundaries, thus causing plasmon interference. By recording and analysing the interference patterns, we can map grain boundaries for a large-area CVD graphene film and probe the electronic properties of individual grain boundaries. Quantitative analysis reveals that grain boundaries form electronic barriers that obstruct both electrical transport and plasmon propagation. The effective width of these barriers (∼10-20 nm) depends on the electronic screening and is on the order of the Fermi wavelength of graphene. These results uncover a microscopic mechanism that is responsible for the low electron mobility observed in CVD-grown graphene, and suggest the possibility of using electronic barriers to realize tunable plasmon reflectors and phase retarders in future graphene-based plasmonic circuits.

Methodology of the 2009 Survey on Living with Chronic Diseases in Canada--hypertension component

INTRODUCTION

The Survey on Living with Chronic Diseases in Canada--hypertension component (SLCDC-H) is a 20-minute cross-sectional telephone survey on hypertension diagnosis and management. Sampled from the 2008 Canadian Community Health Survey (CCHS), the SLCDC-H includes Canadians (aged ≥ 20 years) with self-reported hypertension from the ten provinces.

METHODS

The questionnaire was developed by Delphi technique, externally reviewed and qualitatively tested. Statistics Canada performed sampling strategies, recruitment, data collection and processing. Proportions were weighted to represent the Canadian population, and 95% confidence intervals (CIs) were derived by bootstrap method.

RESULTS

Compared with the CCHS population reporting hypertension, the SLCDC-H sample (n = 6142) is slightly younger (SLCDC-H mean age: 61.2 years, 95% CI: 60.8-61.6; CCHS mean age: 62.2 years, 95% CI: 61.8-62.5), has more post-secondary school graduates (SLCDC-H: 52.0%, 95% CI: 49.7%-54.2%; CCHS: 47.5%, 95% CI: 46.1%-48.9%) and has fewer respondents on hypertension medication (SLCDC-H: 82.5%, 95% CI: 80.9%-84.1%; CCHS: 88.6%, 95% CI: 87.7%-89.6%).

CONCLUSION

Overall, the 2009 SLCDC-H represents its source population and provides novel, comprehensive data on the diagnosis and management of hypertension. The survey has been adapted to other chronic conditions--diabetes, asthma/chronic obstructive pulmonary disease and neurological conditions. The questionnaire is available on the Statistics Canada website; descriptive results have been disseminated by the Public Health Agency of Canada.

Anisotropic electronic state via spontaneous phase separation in strained vanadium dioxide films

We resolved the enigma of anisotropic electronic transport in strained vanadium dioxide (VO2) films by inquiring into the role that strain plays in the nanoscale phase separation in the vicinity of the insulator-to-metal transition. The root source of the anisotropy was visualized as the formation of a peculiar unidirectional stripe state which accompanies the phase transition. Furthermore, nanoscale infrared spectroscopy unveils distinct facets of electron-lattice interplay at three different stages of the phase transition. These stages include the initial formation of sparse nonpercolating metallic domains without noticeable involvement of the lattice followed by an electron-lattice coupled anisotropic stripe state close to percolation which ultimately evolves into a nearly isotropic rutile metallic phase. Our results provide a unique mesoscopic perspective for the tunable macroscopic phenomena in strained metal oxide films.

LXRα-mediated downregulation of FOXM1 suppresses the proliferation of hepatocellular carcinoma cells

Liver X receptors (LXRs), including LXRα and LXRβ isoforms, have important roles in the metabolic regulation of glucose, cholesterol and lipid. Moreover, activation of LXRs also represses the expression of cyclin D1 and cyclin B1, and thus suppresses the proliferation of multiple cancer cells, but the relevant mechanism is not well known. Forkhead box M1 (FOXM1) is a proliferation-specific member of forkhead box family, which is highly expressed in proliferating normal cells and numerous cancer cells. FOXM1 directly activates transcription of cyclin D1 and cyclin B1, resulting in the enhancement of cell cycle progression and cell proliferation. However, it is unclear whether LXRs are involved in the regulation of FOXM1. In this study, we demonstrated that specific LXRs agonists downregulated expression of FOXM1, cyclin D1 and cyclin B1 in hepatocellular carcinoma (HCC) cells, which led to cell cycle and cell proliferation arrest. Knockdown of FOXM1 significantly alleviated LXRs activation-mediated cell cycle arrest and cell growth suppression. Reporter assays showed that the activation of LXRs significantly reduced the transcriptional activity of FOXM1 promoter. Electrophoretic mobility shift assay and chromatin immunoprecipitation assays demonstrated that LXRα but not LXRβ could bind to an inverted repeat IR2 (-52CCGTCAcgTGACCT-39) in the promoter region of FOXM1 gene. Moreover, the xenograft tumor growth and the corresponding FOXM1 expression in nude mice were dramatically repressed by LXRs agonists. Taken together, we conclude that LXRα but not LXRβ functions as a transcriptional repressor for FOXM1 expression. The pathway 'LXRα-FOXM1-cyclin D1/cyclin B1' is a novel mechanism by which LXRs suppress the proliferation of HCC cells, suggesting that the pathway may be a novel target for HCC treatment.

Report summary. Diabetes in Canada: facts and figures from a public health perspective

"Diabetes in Canada: facts and figures from a public health perspective" is the first comprehensive diabetes surveillance report published by the Public Health Agency of Canada. The report aims to support public health professionals and organizations in developing effective, evidence-based public health policies and programs to prevent and manage diabetes and its complications. The report, developed in collaboration with provincial and territorial governments, the Canadian Diabetes Association, Juvenile Diabetes Research Foundation, CNIB, Health Canada and the academic community, uses data from national health surveys and vital statistics, as well as population-based administrative data from the Canadian Chronic Disease Surveillance System (CCDSS). For the first time, the CCDSS contains data from all 13 Canadian jurisdictions. Using CCDSS data representing cases of diagnosed diabetes among Canadians aged one year and older, Diabetes in Canada presents prevalence and incidence national rates from the fiscal year 2008/2009 and national trends from 1998/1999 onwards. The report also outlines sub-populations at higher risk, ways of reducing the risks of developing the disease and its complications, and estimates of related economic costs. In addition, it contains sections on specific populations, including children and youth and First Nations, Inuit and Métis populations.